http://www.rssboard.org/rss-specification 720 https://escholarship.org/uc/nobel_i2011_perlmutter/rss Recent eScholarship items from Saul Perlmutter, UC Berkeley/Lawrence Berkeley Lab (Nobel Prize in Physics, 2011) Tue, 23 Jun 2026 17:16:43 +0000 https://escholarship.org/uc/item/2sv083h3 Type Ia Supernovae (SNe Ia) are standardizable candles that allow us to measure the recent expansion rate of the Universe. Due to uncertainties in progenitor physics, potential astrophysical dependencies may bias cosmological measurements if not properly accounted for. The dependency of the intrinsic luminosity of SNe Ia with their host-galaxy environment is often used to standardize SNe Ia luminosity and is commonly parameterized as a step function. This functional form implicitly assumes two-populations of SNe Ia. In the literature, multiple environmental indicators have been considered, finding different, sometimes incompatible, step function amplitudes. We compare these indicators in the context of a two-populations model, based on their ability to distinguish the two populations. We show that local H α -based specific star formation rate (lsSFR) and global stellar mass are better tracers than, for instance, host galaxy morphology. We... https://escholarship.org/uc/item/2sv083h3 Tue, 29 Mar 2022 00:00:00 +0000 Briday, M Rigault, M Graziani, R Copin, Y Aldering, G Amenouche, M Brinnel, V Kim, AG https://orcid.org/0000-0001-6315-8743 Kim, Y-L Lezmy, J Nicolas, N Nordin, J Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rosnet, P Smith, M https://escholarship.org/uc/item/8fm0n5qz The Nancy Grace Roman Space Telescope (Roman) is an observatory for both wide-field observations and coronagraphy that is scheduled for launch in the mid-2020s. Part of the planned survey is a deep, cadenced field or fields that enable cosmological measurements with type Ia supernovae (SNe Ia). With a pixel scale of 0.″11, the Wide Field Instrument will be undersampled, presenting a difficulty for precisely subtracting the galaxy light underneath the SNe. We use simulated data to validate the ability of a forward-model code (such codes are frequently also called “scene-modeling” codes) to perform precision supernova photometry for the Roman SN survey. Our simulation includes over 760,000 image cutouts around SNe Ia or host galaxies (∼10% of a full-scale survey). To have a realistic 2D distribution of underlying galaxy light, we use the VELA simulated high-resolution images of galaxies. We run each set of cutouts through our forward-modeling code which automatically measures time-dependent... https://escholarship.org/uc/item/8fm0n5qz Thu, 16 Dec 2021 00:00:00 +0000 Rubin, David https://orcid.org/0000-0001-5402-4647 Cikota, Aleksandar Aldering, Greg Fruchter, Andy Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 Sako, Masao https://escholarship.org/uc/item/6637815c We study the spectral diversity of Type Ia supernovae (SNe Ia) at maximum light using high signal-to-noise spectrophotometry of 173 SNe Ia from the Nearby Supernova Factory. We decompose the diversity of these spectra into different extrinsic and intrinsic components, and we construct a nonlinear parameterization of the intrinsic diversity of SNe Ia that preserves pairings of “twin” SNe Ia. We call this parameterization the “Twins Embedding.” Our methodology naturally handles highly nonlinear variability in spectra, such as changes in the photosphere expansion velocity, and uses the full spectrum rather than being limited to specific spectral line strengths, ratios, or velocities. We find that the time evolution of SNe Ia near maximum light is remarkably similar, with 84.6% of the variance in common to all SNe Ia. After correcting for brightness and color, the intrinsic variability of SNe Ia is mostly restricted to specific spectral lines, and we find intrinsic dispersions as... https://escholarship.org/uc/item/6637815c Wed, 17 Nov 2021 00:00:00 +0000 Boone, K Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Bongard, S Buton, C Copin, Y Dixon, S Fouchez, D Gangler, E Gupta, R Hayden, B Hillebrandt, W Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Küsters, D Léget, P-F Mondon, F Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ponder, KA Rabinowitz, D Rigault, M Rubin, D https://orcid.org/0000-0001-5402-4647 Runge, K Saunders, C Smadja, G Suzuki, N Tao, C Taubenberger, S Thomas, RC Vincenzi, M https://escholarship.org/uc/item/2hw7h533 We show how spectra of Type Ia supernovae (SNe Ia) at maximum light can be used to improve cosmological distance estimates. In a companion article, we used manifold learning to build a three-dimensional parameterization of the intrinsic diversity of SNe Ia at maximum light that we call the “Twins Embedding.” In this article, we discuss how the Twins Embedding can be used to improve the standardization of SNe Ia. With a single spectrophotometrically calibrated spectrum near maximum light, we can standardize our sample of SNe Ia with an rms of 0.101 ± 0.007 mag, which corresponds to 0.084 ± 0.009 mag if peculiar velocity contributions are removed and to 0.073 ± 0.008 mag if a larger reference sample were obtained. Our techniques can standardize the full range of SNe Ia, including those typically labeled as peculiar and often rejected from other analyses. We find that traditional light-curve width + color standardization such as SALT2 is not sufficient. The Twins Embedding identifies... https://escholarship.org/uc/item/2hw7h533 Wed, 17 Nov 2021 00:00:00 +0000 Boone, K Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Bongard, S Buton, C Copin, Y Dixon, S Fouchez, D Gangler, E Gupta, R Hayden, B Hillebrandt, W Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Küsters, D Léget, P-F Mondon, F Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ponder, KA Rabinowitz, D Rigault, M Rubin, D https://orcid.org/0000-0001-5402-4647 Runge, K Saunders, C Smadja, G Suzuki, N Tao, C Taubenberger, S Thomas, RC Vincenzi, M https://escholarship.org/uc/item/52f067zx The detailed nature of type Ia supernovae (SNe Ia) remains uncertain, and as survey statistics increase, the question of astrophysical systematic uncertainties arises, notably that of the evolution of SN Ia populations. We study the dependence on redshift of the SN Ia SALT2.4 light-curve stretch, which is a purely intrinsic SN property, to probe its potential redshift drift. The SN stretch has been shown to be strongly correlated with the SN environment, notably with stellar age tracers. We modeled the underlying stretch distribution as a function of redshift, using the evolution of the fraction of young and old SNe Ia as predicted using the SNfactory dataset, and assuming a constant underlying stretch distribution for each age population consisting of Gaussian mixtures. We tested our prediction against published samples that were cut to have marginal magnitude selection effects, so that any observed change is indeed astrophysical and not... https://escholarship.org/uc/item/52f067zx Thu, 19 Aug 2021 00:00:00 +0000 Nicolas, N Rigault, M Copin, Y Graziani, R Aldering, G Briday, M Kim, Y-L Nordin, J Perlmutter, S https://orcid.org/0000-0002-4436-4661 Smith, M https://escholarship.org/uc/item/9p37x9pd We present a sample of normal Type Ia supernovae (SNe Ia) from the Nearby Supernova Factory data set with spectrophotometry at sufficiently late phases to estimate the ejected mass using the bolometric light curve. We measure 56Ni masses from the peak bolometric luminosity, then compare the luminosity in the 56Co-decay tail to the expected rate of radioactive energy release from ejecta of a given mass. We infer the ejected mass in a Bayesian context using a semi-analytic model of the ejecta, incorporating constraints from contemporary numerical models as priors on the density structure and distribution of 56Ni throughout the ejecta. We find a strong correlation between ejected mass and light-curve decline rate, and consequently 56Ni mass, with ejected masses in our data ranging from 0.9 to 1.4 M⊙. Most fast-declining (salt2x1 < −1) normal SNe Ia have significantly sub-Chandrasekhar ejected masses in our fiducial analysis. https://escholarship.org/uc/item/9p37x9pd Tue, 3 Aug 2021 00:00:00 +0000 Scalzo, R Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Bongard, S Buton, C Cellier-Holzem, F Childress, M Chotard, N Copin, Y Fakhouri, HK Gangler, E Guy, J https://orcid.org/0000-0001-9822-6793 Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Kromer, M Nordin, J Nugent, P https://orcid.org/0000-0002-3389-0586 Paech, K Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Runge, K Saunders, C Sim, SA Smadja, G Tao, C Taubenberger, S Thomas, RC Weaver, BA https://escholarship.org/uc/item/69f8n4x8 We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a given supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion... https://escholarship.org/uc/item/69f8n4x8 Tue, 3 Aug 2021 00:00:00 +0000 Saunders, C Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Bongard, S Buton, C Canto, A Cellier-Holzem, F Childress, M Chotard, N Copin, Y Fakhouri, HK Feindt, U Gangler, E Guy, J https://orcid.org/0000-0001-9822-6793 Kerschhaggl, M Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Nordin, J Nugent, P https://orcid.org/0000-0002-3389-0586 Paech, K Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Rubin, D Runge, K Scalzo, R Smadja, G Tao, C Thomas, RC Weaver, BA Wu, C https://escholarship.org/uc/item/2p841362 This document presents the results from the Distances subgroup of the Cosmic Frontier Community Planning Study (Snowmass 2013). We summarize the current state of the field as well as future prospects and challenges. In addition to the established probes using Type Ia supernovae and baryon acoustic oscillations, we also consider prospective methods based on clusters, active galactic nuclei, gravitational wave sirens and strong lensing time delays. https://escholarship.org/uc/item/2p841362 Tue, 3 Aug 2021 00:00:00 +0000 Kim, AG https://orcid.org/0000-0001-6315-8743 Padmanabhan, N Aldering, G Allen, SW Baltay, C Cahn, RN D’Andrea, CB Dalal, N Dawson, KS Denney, KD Eisenstein, DJ Finley, DA Freedman, WL Ho, S Holz, DE Kasen, D Kent, SM Kessler, R Kuhlmann, S Linder, EV Martini, P Nugent, PE https://orcid.org/0000-0002-3389-0586 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Peterson, BM Riess, AG Rubin, D Sako, M Suntzeff, NV Suzuki, N Thomas, RC Wood-Vasey, WM Woosley, SE https://escholarship.org/uc/item/2cv2937r Measuring cosmic bulk flows with Type Ia supernovae from the Nearby Supernova Factory (Corrigendum) https://escholarship.org/uc/item/2cv2937r Tue, 3 Aug 2021 00:00:00 +0000 Feindt, U Kerschhaggl, M Kowalski, M Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Bongard, S Buton, C Canto, A Cellier-Holzem, F Childress, M Chotard, N Copin, Y Fakhouri, HK Gangler, E Guy, J https://orcid.org/0000-0001-9822-6793 Kim, A https://orcid.org/0000-0001-6315-8743 Nugent, P https://orcid.org/0000-0002-3389-0586 Nordin, J Paech, K Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Runge, K Saunders, C Scalzo, R Smadja, G Tao, C Thomas, RC Weaver, BA Wu, C https://escholarship.org/uc/item/131031zx As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization of Type Ia supernovae (SN Ia) for cosmology, we have statistically classified a large sample of nearby SNe Ia into those that are located in predominantly younger or older environments. This classification is based on the specific star formation rate measured within a projected distance of 1 kpc from each SN location (LsSFR). This is an important refinement compared to using the local star formation rate directly, as it provides a normalization for relative numbers of available SN progenitors and is more robust against extinction by dust. We find that the SNe Ia in predominantly younger environments are Δ Y  = 0.163 ± 0.029 mag (5.7 σ ) fainter than those in predominantly older environments after conventional light-curve standardization. This is... https://escholarship.org/uc/item/131031zx Mon, 25 Jan 2021 00:00:00 +0000 Rigault, M Brinnel, V Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Barbary, K Bongard, S Boone, K Buton, C Childress, M Chotard, N Copin, Y Dixon, S Fagrelius, P Feindt, U Fouchez, D Gangler, E Hayden, B Hillebrandt, W Howell, DA Kim, A https://orcid.org/0000-0001-6315-8743 Kowalski, M Kuesters, D Leget, P-F Lombardo, S Lin, Q Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Runge, K Rubin, D Saunders, C Smadja, G Sofiatti, C Suzuki, N Taubenberger, S Tao, C Thomas, RC https://escholarship.org/uc/item/6x76m1sp Context. XMMU J1229+0151 is a rich galaxy cluster with redshift z = 0.975 that was serendipitously detected in X-rays within the scope of the XMM-Newton Distant Cluster Project. Both HST/ACS observations in the i775 and z850 passbands and VLT/FORS2 spectroscopy were obtained, in addition to follow-up Near-Infrared (NIR) imaging in the J- and Ks-bands with NTT/SOFI. Aims. We investigate the photometric, structural, and spectral properties of the early-type galaxies in the high-redshift cluster XMMU J1229+0151.Methods. Source detection and aperture photometry are performed in the optical and NIR imaging. Galaxy morphology is inspected visually and by means of Sersic profile fitting to the 21 spectroscopically confirmed cluster members in the ACS field of view. The i775 - z850 colour-magnitude relation (CMR) is derived with a method based on galaxy magnitudes obtained by fitting the surface brightness of the galaxies with Sersic models. Stellar masses and formation ages of the cluster... https://escholarship.org/uc/item/6x76m1sp Thu, 12 Nov 2020 00:00:00 +0000 Santos, JS Rosati, P Gobat, R Lidman, C Dawson, K Perlmutter, S https://orcid.org/0000-0002-4436-4661 Böhringer, H Balestra, I Mullis, CR Fassbender, R Kohnert, J Lamer, G Rettura, A Rité, C Schwope, A https://escholarship.org/uc/item/5zj801z6 We present a progress report on a project to derive the evolution of the volumetric supernova Type Ia rate from the Supernova Legacy Survey. Our preliminary estimate of the rate evolution divides the sample from Neill et al. into two redshift bins: 0.2 < z < 0.4, and 0.4 < z < 0.6. We extend this by adding a bin from the sample analyzed in Sullivan et al. in the range 0.6 < z < 0.75 from the same time period. We compare the derived trend with previously published rates and a supernova Type Ia production model having two components: one component associated closely with star formation and an additional component associated with host galaxy mass. Our observed trend is consistent with this model, which predicts a rising SN Ia rate out to at least z = 2. https://escholarship.org/uc/item/5zj801z6 Thu, 12 Nov 2020 00:00:00 +0000 Neill, James D Sullivan, M Balam, D Pritchet, CJ Howell, DA Perrett, K Astier, P Aubourg, E Basa, S Carlberg, RG Conley, A Fabbro, S Fouchez, D Guy, J https://orcid.org/0000-0001-9822-6793 Hook, I Pain, R Palanque‐Delabrouille, N Regnault, N Rich, J Taillet, R Aldering, G Antilogus, P Arsenijevic, V Balland, C Baumont, S Bronder, J Ellis, RS Filiol, M Gonçalves, AC Hardin, D Kowalski, M Lidman, C Lusset, V Mouchet, M Mourao, A Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ripoche, P Schlegel, D https://orcid.org/0000-0002-5042-5088 Tao, C https://escholarship.org/uc/item/5nr3s7jj We present a measurement of the distant Type Ia supernova (SN Ia) rate derived from the first 2 yr of the Canada-France-Hawaii Telescope Supernova Legacy Survey. We observed four 1° × 1° fields with a typical temporal frequency of ⟨Δt⟩ ∼ 4 observer-frame days over time spans of 158-211 days per season for each field, with breaks during the full Moon. We used 8-10 m class telescopes for spectroscopic follow-up to confirm our candidates and determine their redshifts. Our starting sample consists of 73 spectroscopically verified SNe Ia in the redshift range 0.2 < z < 0.6. We derive a volumetric SN Ia rate of rV(⟨z⟩ = 0.47) = × 10-4 yr-1 Mpc3, assuming h = 0.7, Ωm = 0.3, and a flat cosmology. Using recently published galaxy luminosity functions derived in our redshift range, we derive a SN Ia rate per unit luminosity of rL(⟨z⟩ = 0.47) = 0.154(syst.)(stat.) SN units. Using our rate alone, we place an upper limit on the component of SN Ia production that tracks the cosmic star... https://escholarship.org/uc/item/5nr3s7jj Thu, 12 Nov 2020 00:00:00 +0000 Neill, JD Sullivan, M Balam, D Pritchet, CJ Howell, DA Perrett, K Astier, P Aubourg, E Basa, S Carlberg, RG Conley, A Fabbro, S Fouchez, D Guy, J https://orcid.org/0000-0001-9822-6793 Hook, I Pain, R Palanque-Delabrouille, N Regnault, N Rich, J Taillet, R Aldering, G Antilogus, P Arsenijevic, V Balland, C Baumont, S Bronder, J Ellis, RS Filiol, M Gonçalves, AC Hardin, D Kowalski, M Lidman, C Lusset, V Mouchet, M Mourao, A Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ripoche, P Schlegel, D https://orcid.org/0000-0002-5042-5088 Tao, C https://escholarship.org/uc/item/3554x7b2 We examine the utility of very high redshift Type Ia supernovae for cosmology and systematic uncertainty control. Next generation space surveys such as the Supernova/Acceleration Probe (SNAP) will obtain thousands of supernovae at z > 1.7, beyond the design redshift for which the supernovae will be exquisitely characterized. We find that any z ≳ 2 standard candles' use for cosmological parameter estimation is quite modest and subject to pitfalls; we examine gravitational lensing, redshift calibration, and contamination effects in some detail. The very high redshift supernovae - both thermonuclear and core collapse - will provide copious interesting information on star formation, environment, and evolution. However, the new observational systematics that must be faced, as well as the limited expansion of SN-parameter space afforded, does not point to high value for 1.7 < z < 3 SNe Ia in controlling evolutionary systematics relative to what SNAP can already achieve at z... https://escholarship.org/uc/item/3554x7b2 Thu, 12 Nov 2020 00:00:00 +0000 Aldering, Greg Kim, Alex G https://orcid.org/0000-0001-6315-8743 Kowalski, Marek Linder, Eric V Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 https://escholarship.org/uc/item/2r04k5mc We show that Type Ia supernovae (SNe Ia) are formed within both very young and old stellar populations, with observed rates that depend on the stellar mass and mean star formation rates (SFRs) of their host galaxies. Models in which the SN Ia rate depends solely on host galaxy stellar mass are ruled out with >99% confidence. Our analysis is based on 100 spectroscopically confirmed SNe Ia, plus 24 photometrically classified events, all from the Supernova Legacy Survey (SNLS) and distributed over 0.2 < z < 0.75. We estimate stellar masses and SFRs for the SN Ia host galaxies by fitting their broadband spectral energy distributions with the galaxy spectral synthesis code PÉGASE.2. We show that the SN Ia rate per unit mass is proportional to the specific SFR of the parent galaxies - more vigorously star-forming galaxies host more SNe Ia per unit stellar mass, broadly equivalent to the trend of increasing SN Ia rate in later type galaxies seen in the local universe. Following... https://escholarship.org/uc/item/2r04k5mc Thu, 12 Nov 2020 00:00:00 +0000 Sullivan, M Le Borgne, D Pritchet, CJ Hodsman, A Neill, JD Howell, DA Carlberg, RG Astier, P Aubourg, E Balam, D Basa, S Conley, A Fabbro, S Fouchez, D Guy, J https://orcid.org/0000-0001-9822-6793 Hook, I Pain, R Palanque-Delabrouille, N Perrett, K Regnault, N Rich, J Taillet, R Baumont, S Bronder, J Ellis, RS Filiol, M Lusset, V Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ripoche, P Tao, C https://escholarship.org/uc/item/9wh6n6nr We compile a sample of spectroscopically and photometrically selected cluster galaxies from four high-redshift galaxy clusters (1.59 < z < 1.71) from the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS), and a comparison field sample selected from the UKIDSS Deep Survey. Using near-infrared imaging from the Hubble Space Telescope, we classify potential mergers involving massive (M∗ ≥ 3 × 1010M⊙) cluster members by eye, based on morphological properties such as tidal distortions, double nuclei, and projected near neighbors within 20 kpc. With a catalog of 23 spectroscopic and 32 photometric massive cluster members across the four clusters and 65 spectroscopic and 26 photometric comparable field galaxies, we find that after taking into account contamination from interlopers, 11+7.0-5.6% of the cluster members are involved in potential mergers, compared to 24.7+5.3-4.6% of the field galaxies. We see no evidence of merger enhancement in the central cluster environment... https://escholarship.org/uc/item/9wh6n6nr Thu, 8 Oct 2020 00:00:00 +0000 Delahaye, AG Webb, TMA Nantais, J DeGroot, A Wilson, G Muzzin, A Yee, HKC Foltz, R Noble, AG Demarco, R Tudorica, A Cooper, MC https://orcid.org/0000-0003-1371-6019 Lidman, C Perlmutter, S https://orcid.org/0000-0002-4436-4661 Hayden, B Boone, K Surace, J https://escholarship.org/uc/item/7gz848wx © 2019. The American Astronomical Society. All rights reserved. We present the Massive and Distant Clusters of WISE Survey (MaDCoWS), a search for galaxy clusters at 0.7 ≲ z ≲ 1.5 based upon data from the Wide-field Infrared Survey Explorer (WISE) mission. MaDCoWS is the first cluster survey capable of discovering massive clusters at these redshifts over the full extragalactic sky. The search is divided into two regions - the region of the extragalactic sky covered by Pan-STARRS (δ > -30°) and the remainder of the southern extragalactic sky at δ < -30° for which shallower optical data from the SuperCOSMOS Sky Survey is available. In this paper, we describe the search algorithm, characterize the sample, and present the first MaDCoWS data release - catalogs of the 2433 highest amplitude detections in the WISE-Pan-STARRS region and the 250 highest amplitude detections in the WISE-SuperCOSMOS region. A total of 1723 of the detections from the WISE-Pan-STARRS sample have also... https://escholarship.org/uc/item/7gz848wx Thu, 8 Oct 2020 00:00:00 +0000 Gonzalez, AH Gettings, DP Brodwin, M Eisenhardt, PRM Stanford, SA Wylezalek, D Decker, B Marrone, DP Moravec, E O'Donnell, C Stalder, B Stern, D Abdulla, Z Brown, G Carlstrom, J Chambers, KC Hayden, B Lin, YT Magnier, E Masci, FJ Mantz, AB McDonald, M Mo, W Perlmutter, S https://orcid.org/0000-0002-4436-4661 Wright, EL Zeimann, GR https://escholarship.org/uc/item/6p45s17n We present ALMA CO (2-1) detections in 11 gas-rich cluster galaxies at z ∼ 1.6, constituting the largest sample of molecular gas measurements in z > 1.5 clusters to date. The observations span three galaxy clusters, derived from the Spitzer Adaptation of the Red-sequence Cluster Survey. We augment the >5σ detections of the CO (2-1) fluxes with multi-band photometry, yielding stellar masses and infrared-derived star formation rates, to place some of the first constraints on molecular gas properties in z ∼ 1.6 cluster environments. We measure sizable gas reservoirs of 0.5-2 × 1011 M in these objects, with high gas fractions (f gas) and long depletion timescales (τ), averaging 62% and 1.4 Gyr, respectively. We compare our cluster galaxies to the scaling relations of the coeval field, in the context of how gas fractions and depletion timescales vary with respect to the star-forming main sequence. We find that our cluster galaxies lie systematically off the field scaling relations... https://escholarship.org/uc/item/6p45s17n Thu, 8 Oct 2020 00:00:00 +0000 Noble, AG McDonald, M Muzzin, A Nantais, J Rudnick, G van Kampen, E Webb, TMA Wilson, G Yee, HKC Boone, K Cooper, MC https://orcid.org/0000-0003-1371-6019 DeGroot, A Delahaye, A Demarco, R Foltz, R Hayden, B Lidman, C Manilla-Robles, A Perlmutter, S https://orcid.org/0000-0002-4436-4661 https://escholarship.org/uc/item/4qr7h5bd © 2018. The Astronomical Society of the Pacific. All rights reserved. We have discovered an anomalous behavior of CCD readout electronics that affects their use in many astronomical applications. An offset in the digitization of the CCD output voltage that depends on the binary encoding of one pixel is added to pixels that are read out one, two, and/or three pixels later. One result of this effect is the introduction of a differential offset in the background when comparing regions with and without flux from science targets. Conventional data reduction methods do not correct for this offset. We find this effect in 16 of 22 instruments investigated, covering a variety of telescopes and many different front-end electronics systems. The affected instruments include LRIS and DEIMOS on the Keck telescopes, WFC3 UVIS and STIS on HST, MegaCam on CFHT, SNIFS on the UH88 telescope, GMOS on the Gemini telescopes, HSC on Subaru, and FORS on VLT. The amplitude of the introduced offset is... https://escholarship.org/uc/item/4qr7h5bd Thu, 8 Oct 2020 00:00:00 +0000 Boone, K Aldering, G Copin, Y Dixon, S Domagalski, RS Gangler, E Pecontal, E Perlmutter, S https://orcid.org/0000-0002-4436-4661 https://escholarship.org/uc/item/4mq4259h Hot, dust-obscured galaxies, or "Hot DOGs," are a rare, dusty, hyperluminous galaxy population discovered by the WISE mission. Predominantly at redshifts 2-3, they include the most luminous known galaxies in the universe. Their high luminosities likely come from accretion onto highly obscured supermassive black holes (SMBHs). We have conducted a pilot survey to measure the SMBH masses of five z ∼ 2 Hot DOGs via broad Hα emission lines, using Keck/MOSFIRE and Gemini/FLAMINGOS-2. We detect broad Hα emission in all five Hot DOGs. We find substantial corresponding SMBH masses for these Hot DOGs (∼ 109 M⊙), and their derived Eddington ratios are close to unity. These z ∼ 2 Hot DOGs are the most luminous active galactic nuclei for their BH masses, suggesting that they are accreting at the maximum rates for their BHs. A similar property is found for known z ∼ 6 quasars. Our results are consistent with scenarios in which Hot DOGs represent a transitional, high-accretion phase between... https://escholarship.org/uc/item/4mq4259h Thu, 8 Oct 2020 00:00:00 +0000 Wu, Jingwen Jun, Hyunsung D Assef, Roberto J Tsai, Chao-Wei Wright, Edward L Eisenhardt, Peter RM Blain, Andrew Stern, Daniel Díaz-Santos, Tanio Denney, Kelly D Hayden, Brian T Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 Aldering, Greg Boone, Kyle Fagrelius, Parker https://escholarship.org/uc/item/2ng9r40f © 2017. The American Astronomical Society. All rights reserved. We compare the isophote shape parameter a4 of early-type galaxies (ETGs) between z ∼ 1 and 0 as a proxy for dynamics to investigate the epoch at which the dynamical properties of ETGs are established, using cluster ETG samples with stellar masses of log(M∗/M⊙) ≥ 10.5 which have spectroscopic redshifts. We have 130 ETGs from the Hubble Space Telescope Cluster Supernova Survey for z ∼ 1 and 355 ETGs from the Sloan Digital Sky Survey for z ∼ 0. We have developed an isophote shape analysis method, which can be used for high-redshift galaxies and has been carefully compared with published results. We have applied the same method for both the z ∼ 1 and 0 samples. We find similar dependence of the a4 parameter on the mass and size at z ∼ 1 and 0; the main population of ETGs changes from disky to boxy at a critical stellar mass of log(M∗/M⊙) ∼ 11.5 with the massive end dominated by boxy. The disky ETG fraction decreases with... https://escholarship.org/uc/item/2ng9r40f Thu, 8 Oct 2020 00:00:00 +0000 Mitsuda, K Doi, M Morokuma, T Suzuki, N Yasuda, N Perlmutter, S https://orcid.org/0000-0002-4436-4661 Aldering, G Meyers, J https://escholarship.org/uc/item/2cq5q7rp Using a sample of four galaxy clusters at 1.35 < z < 1.65 and 10 galaxy clusters at 0.85 < z < 1.35, we measure the environmental quenching timescale, t Q, corresponding to the time required after a galaxy is accreted by a cluster for it to fully cease star formation. Cluster members are selected by a photometric-redshift criterion, and categorized as star-forming, quiescent, or intermediate according to their dust-corrected rest-frame colors and magnitudes. We employ a "delayed-then-rapid" quenching model that relates a simulated cluster mass accretion rate to the observed numbers of each type of galaxy in the cluster to constrain t Q. For galaxies of mass M ∗ 1010.5 M o, we find a quenching timescale of t Q = Gyr in the z ∼ 1.5 cluster sample, and Gyr at z ∼ 1. Using values drawn from the literature, we compare the redshift evolution of t Q to timescales predicted for different physical quenching mechanisms. We find t Q to depend on host halo mass such that quenching... https://escholarship.org/uc/item/2cq5q7rp Thu, 8 Oct 2020 00:00:00 +0000 Foltz, R Wilson, G https://orcid.org/0000-0002-6572-7089 Muzzin, A Cooper, MC https://orcid.org/0000-0003-1371-6019 Nantais, J van der Burg, RFJ Cerulo, P Chan, J Fillingham, SP Surace, J Webb, T Noble, A Lacy, M McDonald, M Rudnick, G Lidman, C Demarco, R Hlavacek-Larrondo, J Yee, HKC Perlmutter, S https://orcid.org/0000-0002-4436-4661 Hayden, B https://escholarship.org/uc/item/1fd8d566 © 2019. The American Astronomical Society. All rights reserved.. We present a detailed high-resolution weak-lensing study of SPT-CL J2106-5844 at z = 1.132, claimed to be the most massive system discovered at z > 1 in the South Pole Telescope Sunyaev-Zel'dovich survey. Based on the deep imaging data from the Advanced Camera for Surveys and Wide Field Camera 3 on board the Hubble Space Telescope, we find that the cluster mass distribution is asymmetric, composed of a main clump and a subclump ∼640 kpc west thereof. The central clump is further resolved into two smaller northwestern and southeastern substructures separated by ∼150 kpc. We show that this rather complex mass distribution is more consistent with the cluster galaxy distribution than a unimodal distribution as previously presented. The northwestern substructure coincides with the brightest cluster galaxy and the X-ray peak while the southeastern one agrees with the location of the peak in number density. These morphological... https://escholarship.org/uc/item/1fd8d566 Thu, 8 Oct 2020 00:00:00 +0000 Kim, J Jee, MJ https://orcid.org/0000-0002-5751-3697 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Hayden, B Rubin, D https://orcid.org/0000-0001-5402-4647 Huang, X Aldering, G Ko, J https://escholarship.org/uc/item/0td139f0 Scientific analyses commonly compose multiple single-process programs into a dataflow. An end-to-end dataflow of single-process programs is known as a many-task application. Typically, tools from the HPC software stack are used to parallelize these analyses. In this work, we investigate an alternate approach that uses Apache Spark - a modern big data platform - to parallelize many-task applications. We present Kira, a flexible and distributed astronomy image processing toolkit using Apache Spark. We then use the Kira toolkit to implement a Source Extractor application for astronomy images, called Kira SE. With Kira SE as the use case, we study the programming flexibility, dataflow richness, scheduling capacity and performance of Apache Spark running on the EC2 cloud. By exploiting data locality, Kira SE achieves a 3.7 χ speedup over an equivalent C program when analyzing a 1TB dataset using 512 cores on the Amazon EC2 cloud. Furthermore, we show that by leveraging software originally... https://escholarship.org/uc/item/0td139f0 Thu, 8 Oct 2020 00:00:00 +0000 Zhang, Zhao Barbary, Kyle Nothaft, Frank Austin Sparks, Evan Zahn, Oliver Franklin, Michael J Patterson, David A Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 https://escholarship.org/uc/item/0dj743wz We present a weak-lensing study of SPT-CL J2040-4451 and IDCS J1426+3508 at z = 1.48 and 1.75, respectively. The two clusters were observed in our "See Change" program, a Hubble Space Telescope survey of 12 massive high-redshift clusters aimed at high-z supernova measurements and weak-lensing estimation of accurate cluster masses. We detect weak but significant galaxy shape distortions using infrared images from the Wide Field Camera 3 (WFC3), which has not yet been used for weak-lensing studies. Both clusters appear to possess relaxed morphology in projected mass distribution, and their mass centroids agree nicely with those defined by both the galaxy luminosity and X-ray emission. Using a Navarro-Frenk-White profile, for which we assume that the mass is tightly correlated with the concentration parameter, we determine the masses of SPT-CL J2040-4451 and IDCS J1426 + 3508 to be M200 = 8.6+1.7-1.4 × 1014 Moand 2.2+1.1-0.7 × 1014Mo, respectively. The weak-lensing mass of SPT-CL... https://escholarship.org/uc/item/0dj743wz Thu, 8 Oct 2020 00:00:00 +0000 Jee, M James Ko, Jongwan Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 Gonzalez, Anthony Brodwin, Mark Linder, Eric Eisenhardt, Peter https://escholarship.org/uc/item/92z3p6t3 The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties that may help to reveal the origin of the “super-Chandrasekhar” (or 03fg-like) group. The optical spectrum is typical of a 03fg-like SN Ia, but the light curves are unlike those of any SNe Ia observed. The light curves of LSQ14fmg rise extremely slowly. At −23 rest-frame days relative to B-band maximum, LSQ14fmg is already brighter than mag before host extinction correction. The observed color curves show a flat evolution from the earliest observation to approximately 1 week after maximum. The near-infrared light curves peak brighter than −20.5 mag in the J and H bands, far more luminous than any 03fg-like SNe Ia with near-infrared observations. At 1 month past maximum, the optical light curves decline rapidly. The early, slow rise and flat color evolution are interpreted to result from an additional excess flux from a power source other than the radioactive decay of the synthesized 56Ni. The excess flux matches... https://escholarship.org/uc/item/92z3p6t3 Sun, 4 Oct 2020 00:00:00 +0000 Hsiao, EY Hoeflich, P Ashall, C Lu, J Contreras, C Burns, CR Phillips, MM Galbany, L Anderson, JP Baltay, C Baron, E Castellón, S Davis, S Freedman, Wendy L Gall, C Gonzalez, C Graham, ML Hamuy, M Holoien, TW-S Karamehmetoglu, E Krisciunas, K Kumar, S Kuncarayakti, H Morrell, N Moriya, TJ Nugent, PE https://orcid.org/0000-0002-3389-0586 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Persson, SE Piro, AL Rabinowitz, D Roth, M Shahbandeh, M Shappee, BJ Stritzinger, MD Suntzeff, NB Taddia, F Uddin, SA https://escholarship.org/uc/item/99j5n7xc © P.-F. Léget et al. 2020. Context. Type Ia supernovae (SNe Ia) are widely used to measure the expansion of the Universe. Improving distance measurements of SNe Ia is one technique to better constrain the acceleration of expansion and determine its physical nature. Aims. This document develops a new SNe Ia spectral energy distribution (SED) model, called the SUpernova Generator And Reconstructor (SUGAR), which improves the spectral description of SNe Ia, and consequently could improve the distance measurements. Methods. This model was constructed from SNe Ia spectral properties and spectrophotometric data from the Nearby Supernova Factory collaboration. In a first step, a principal component analysis-like method was used on spectral features measured at maximum light, which allowed us to extract the intrinsic properties of SNe Ia. Next, the intrinsic properties were used to extract the average extinction curve. Third, an interpolation using Gaussian processes facilitated using... https://escholarship.org/uc/item/99j5n7xc Wed, 19 Aug 2020 00:00:00 +0000 Léget, PF Gangler, E Mondon, F Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Barbary, K Bongard, S Boone, K Buton, C Chotard, N Copin, Y Dixon, S Fagrelius, P Feindt, U Fouchez, D Hayden, B Hillebrandt, W Kim, A https://orcid.org/0000-0001-6315-8743 Kowalski, M Kuesters, D Lombardo, S Lin, Q Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ponder, KA Pruzhinskaya, MV Rabinowitz, D Rigault, M Runge, K Rubin, D https://orcid.org/0000-0001-5402-4647 Saunders, C Says, LP Smadja, G Sofiatti, C Suzuki, N Taubenberger, S Tao, C Thomas, RC https://escholarship.org/uc/item/8467061n Context. Type Ia supernovae (SNe Ia) are widely used to measure the expansion of the Universe. To perform such measurements the luminosity and cosmological redshift (z) of the SNe Ia have to be determined. The uncertainty on z includes an unknown peculiar velocity, which can be very large for SNe Ia in the virialized cores of massive clusters. Aims. We determine which SNe Ia exploded in galaxy clusters using 145 SNe Ia from the Nearby Supernova Factory. We then study how the correction for peculiar velocities of host galaxies inside the clusters improves the Hubble residuals. Methods. We found 11 candidates for membership in clusters. We applied the biweight technique to estimate the redshift of a cluster. Then, we used the galaxy cluster redshift instead of the host galaxy redshift to construct the Hubble diagram. Results. For SNe Ia inside galaxy clusters, the dispersion around the Hubble diagram when peculiar velocities are taken into account is smaller compared with a case... https://escholarship.org/uc/item/8467061n Mon, 2 Dec 2019 00:00:00 +0000 Léget, P-F Pruzhinskaya, MV Ciulli, A Gangler, E Aldering, G Antilogus, P Aragon, C Bailey, S Baltay, C Barbary, K Bongard, S Boone, K Buton, C Childress, M Chotard, N Copin, Y Dixon, S Fagrelius, P Feindt, U Fouchez, D Gris, P Hayden, B Hillebrandt, W Howell, DA Kim, A https://orcid.org/0000-0001-6315-8743 Kowalski, M Kuesters, D Lombardo, S Lin, Q Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Runge, K Rubin, D Saunders, C Says, L-P Smadja, G Sofiatti, C Suzuki, N Taubenberger, S Tao, C Thomas, RC https://escholarship.org/uc/item/578825h2 Context. Observations of type Ia supernovae (SNe Ia) can be used to derive accurate cosmological distances through empirical standardization techniques. Despite this success neither the progenitors of SNe Ia nor the explosion process are fully understood. The U-band region has been less well observed for nearby SNe, due to technical challenges, but is the most readily accessible band for high-redshift SNe. Aims. Using spectrophotometry from the Nearby Supernova Factory, we study the origin and extent of U-band spectroscopic variations in SNe Ia and explore consequences for their standardization and the potential for providing new insights into the explosion process. Methods. We divide the U-band spectrum into four wavelength regions λ(uNi), λ(uTi), λ(uSi) and λ(uCa). Two of these span the Ca H&K λλ 3934, 3969 complex. We employ spectral synthesis using SYNAPPS to associate the two bluer regions with Ni/Co and Ti. Results. The flux of the uTi feature is an extremely sensitive... https://escholarship.org/uc/item/578825h2 Mon, 2 Dec 2019 00:00:00 +0000 Nordin, J Aldering, G Antilogus, P Aragon, C Bailey, S Baltay, C Barbary, K Bongard, S Boone, K Brinnel, V Buton, C Childress, M Chotard, N Copin, Y Dixon, S Fagrelius, P Feindt, U Fouchez, D Gangler, E Hayden, B Hillebrandt, W Kim, A https://orcid.org/0000-0001-6315-8743 Kowalski, M Kuesters, D Leget, P-F Lombardo, S Lin, Q Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Runge, K Rubin, D Saunders, C Smadja, G Sofiatti, C Suzuki, N Taubenberger, S Tao, C Thomas, RC https://escholarship.org/uc/item/9m68t1b8 Abstract As a candidate ‘super-Chandrasekhar’ or 09dc-like Type Ia supernova (SN Ia), SN 2012dn shares many characteristics with other members of this remarkable class of objects but lacks their extraordinary luminosity. Here, we present and discuss the most comprehensive optical data set of this SN to date, comprised of a densely sampled series of early-time spectra obtained within the Nearby Supernova Factory project, plus photometry and spectroscopy obtained at the VLT about 1 yr after the explosion. The light curves, colour curves, spectral time series and ejecta velocities of SN 2012dn are compared with those of other 09dc-like and normal SNe Ia, the overall variety within the class of 09dc-like SNe Ia is discussed, and new criteria for 09dc-likeness are proposed. Particular attention is directed to additional insight that the late-phase data provide. The nebular spectra show forbidden lines of oxygen and calcium, elements... https://escholarship.org/uc/item/9m68t1b8 Fri, 8 Nov 2019 00:00:00 +0000 Taubenberger, S Floers, A Vogl, C Kromer, M Spyromilio, J Aldering, G Antilogus, P Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Bongard, S Boone, K Buton, C Chotard, N Copin, Y Dixon, S Fouchez, D Fransson, C Gangler, E Gupta, RR Hachinger, S Hayden, B Hillebrandt, W Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Leget, P-F Leibundgut, B Mazzali, PA Noebauer, UM Nordin, J Pain, R Pakmor, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ponder, KA Rabinowitz, D Rigault, M Rubin, D Runge, K Saunders, C Smadja, G Tao, C Thomas, RC https://escholarship.org/uc/item/86j1k9cv SN Ia cosmology depends on the ability to fit and standardize observations of supernova magnitudes with an empirical model. We present here a series of new models of SN Ia spectral time series that capture a greater amount of supernova diversity than is possible with the models that are currently customary. These are entitled SuperNova Empirical MOdels (SNEMO; https://snfactory.lbl.gov/snemo). The models are constructed using spectrophotometric time series from 172 individual supernovae from the Nearby Supernova Factory, comprising more than 2000 spectra. Using the available observations, Gaussian processes are used to predict a full spectral time series for each supernova. A matrix is constructed from the spectral time series of all the supernovae, and Expectation Maximization Factor Analysis is used to calculate the principal components of the data. K-fold cross-validation then determines the selection of model parameters and accounts for color variation in the data. Based on... https://escholarship.org/uc/item/86j1k9cv Wed, 7 Aug 2019 00:00:00 +0000 Saunders, C Aldering, G Antilogus, P Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Barbary, K Baugh, D Boone, K Bongard, S Buton, C Chen, J Chotard, N Copin, Y Dixon, S Fagrelius, P Fakhouri, HK Feindt, U Fouchez, D Gangler, E Hayden, B Hillebrandt, W Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Küsters, D Leget, P-F Lombardo, S Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Rubin, D https://orcid.org/0000-0001-5402-4647 Runge, K Smadja, G Sofiatti, C Suzuki, N Tao, C Taubenberger, S Thomas, RC Vincenzi, M https://escholarship.org/uc/item/2kh1d38b The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year program to obtain optical and near-infrared observations of a “Cosmology” sample of ∼100 Type Ia supernovae located in the smooth Hubble flow (0.03 ≲ z ≲ 0.10). Light curves were also obtained of a “Physics” sample composed of 90 nearby Type Ia supernovae at z ≤ 0.04 selected for near-infrared spectroscopic timeseries observations. The primary emphasis of the CSP-II is to use the combination of optical and near-infrared photometry to achieve a distance precision of better than 5%. In this paper, details of the supernova sample, the observational strategy, and the characteristics of the photometric data are provided. In a companion paper, the near-infrared spectroscopy component of the project is presented. https://escholarship.org/uc/item/2kh1d38b Tue, 19 Mar 2019 00:00:00 +0000 Phillips, MM Contreras, Carlos Hsiao, EY Morrell, Nidia Burns, Christopher R Stritzinger, Maximilian Ashall, C Freedman, Wendy L Hoeflich, P Persson, SE Piro, Anthony L Suntzeff, Nicholas B Uddin, Syed A Anais, Jorge Baron, E Busta, Luis Campillay, Abdo Castellón, Sergio Corco, Carlos Diamond, T Gall, Christa Gonzalez, Consuelo Holmbo, Simon Krisciunas, Kevin Roth, Miguel Serón, Jacqueline Taddia, F Torres, Simón Anderson, JP Baltay, C Folatelli, Gastón Galbany, L Goobar, A Hadjiyska, Ellie Hamuy, Mario Kasliwal, Mansi Lidman, C Nugent, Peter E https://orcid.org/0000-0002-3389-0586 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, David Ryder, Stuart D Schmidt, Brian P Shappee, BJ Walker, Emma S https://escholarship.org/uc/item/6zx853d1 Shifting the focus of Type Ia supernova (SN Ia) cosmology to the near infrared (NIR) is a promising way to significantly reduce the systematic errors, as the strategy minimizes our reliance on the empirical width-luminosity relation and uncertain dust laws. Observations in the NIR are also crucial for our understanding of the origins and evolution of these events, further improving their cosmological utility. Any future experiments in the rest-frame NIR will require knowledge of the SN Ia NIR spectroscopic diversity, which is currently based on a small sample of observed spectra. Along with the accompanying paper, Phillips et al., we introduce the Carnegie Supernova Project-II (CSP-II), to follow-up nearby SNe Ia in both the optical and the NIR. In particular, this paper focuses on the CSP-II NIR spectroscopy program, describing the survey strategy, instrumental setups, data reduction, sample characteristics, and future analyses on the data set. In collaboration with the Harvard-Smithsonian... https://escholarship.org/uc/item/6zx853d1 Wed, 6 Feb 2019 00:00:00 +0000 Hsiao, EY Phillips, MM Marion, GH Kirshner, RP Morrell, N Sand, DJ Burns, CR Contreras, C Hoeflich, P Stritzinger, MD Valenti, S https://orcid.org/0000-0001-8818-0795 Anderson, JP Ashall, C Baltay, C Baron, E Banerjee, DPK Davis, S Diamond, TR Folatelli, G Freedman, Wendy L Förster, F Galbany, L Gall, C González-Gaitán, S Goobar, A Hamuy, M Holmbo, S Kasliwal, MM Krisciunas, K Kumar, S Lidman, C Lu, J Nugent, PE https://orcid.org/0000-0002-3389-0586 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Persson, SE Piro, AL Rabinowitz, D Roth, M Ryder, SD Schmidt, BP Shahbandeh, M Suntzeff, NB Taddia, F Uddin, S Wang, L https://escholarship.org/uc/item/3vg8b3cs Correcting Type Ia Supernova brightnesses for extinction by dust has proven to be a vexing problem. Here we study the dust foreground to the highly reddened SN 2012cu, which is projected onto a dust lane in the galaxy NGC 4772. The analysis is based on multi-epoch, spectrophotometric observations spanning from 3300-9200 Å, obtained by the Nearby Supernova Factory. Phase-matched comparison of the spectroscopically twinned SN 2012cu and SN 2011fe across 10 epochs results in the best-fit color excess of (E (B - V), RMS) = (1.00, 0.03) and total-to-selective extinction ratio of (RV, RMS) = (2.95, 0.08) toward SN 2012cu within its host galaxy. We further identify several diffuse interstellar bands and compare the 5780 Å band with the dust-to-band ratio for the Milky Way (MW). Overall, we find the foreground dust-extinction properties for SN 2012cu to be consistent with those of the MW. Furthermore, we find no evidence for significant time variation in any of these extinction tracers.... https://escholarship.org/uc/item/3vg8b3cs Wed, 29 Aug 2018 00:00:00 +0000 Huang, X Raha, Z Aldering, G Antilogus, P Bailey, S Baltay, C Barbary, K Baugh, D Boone, K Bongard, S Buton, C Chen, J Chotard, N Copin, Y Fagrelius, P Fakhouri, HK Feindt, U Fouchez, D Gangler, E Hayden, B Hillebrandt, W Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Leget, P-F Lombardo, S Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Rigault, M Rubin, D Runge, K Saunders, C Smadja, G Sofiatti, C Stocker, A Suzuki, N Taubenberger, S Tao, C Thomas, RC https://escholarship.org/uc/item/5q18t7vw Aims. The scientific yield of current and future optical surveys is increasingly limited by systematic uncertainties in the flux calibration. This is the case for type Ia supernova (SN Ia) cosmology programs, where an improved calibration directly translates into improved cosmological constraints. Current methodology rests on models of stars. Here we aim to obtain flux calibration that is traceable to state-of-the-art detector-based calibration. Methods. We present the SNIFS Calibration Apparatus (SCALA), a color (relative) flux calibration system developed for the SuperNova integral field spectrograph (SNIFS), operating at the University of Hawaii 2.2 m (UH 88) telescope. Results. By comparing the color trend of the illumination generated by SCALA during two commissioning runs, and to previous laboratory measurements, we show that we can determine the light emitted by SCALA with a long-term repeatability better than 1%. We describe the calibration procedure necessary to control... https://escholarship.org/uc/item/5q18t7vw Tue, 28 Aug 2018 00:00:00 +0000 Lombardo, S Küsters, D Kowalski, M Aldering, G Antilogus, P Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Barbary, K Baugh, D Bongard, S Boone, K Buton, C Chen, J Chotard, N Copin, Y Dixon, S Fagrelius, P Feindt, U Fouchez, D Gangler, E Hayden, B Hillebrandt, W Hoffmann, A Kim, AG https://orcid.org/0000-0001-6315-8743 Leget, P-F McKay, L Nordin, J Pain, R Pécontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Reif, K Rigault, M Rubin, D Runge, K Saunders, C Smadja, G Suzuki, N Taubenberger, S Tao, C Thomas, RC https://escholarship.org/uc/item/9wd067wg We introduce a method for identifying “twin” Type Ia supernovae (SNe Ia) and using them to improve distance measurements. This novel approach to SN Ia standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). We begin with a well-measured set of SNe, find pairs whose spectra match well across the entire optical window, and then test whether this leads to a smaller dispersion in their absolute brightnesses. This analysis is completed in a blinded fashion, ensuring that decisions made in implementing the method do not inadvertently bias the result. We find that pairs of SNe with more closely matched spectra indeed have reduced brightness dispersion. We are able to standardize this initial set of SNfactory SNe to 0.083 ± 0.012 mag, implying a dispersion of 0.072 ± 0.010 mag in the absence of peculiar velocities. We estimate that with larger numbers of comparison SNe, e.g., using the final SNfactory spectrophotometric... https://escholarship.org/uc/item/9wd067wg Tue, 21 Aug 2018 00:00:00 +0000 Fakhouri, HK Boone, K Aldering, G Antilogus, P Aragon, C Bailey, S https://orcid.org/0000-0003-4162-6619 Baltay, C Barbary, K Baugh, D Bongard, S Buton, C Chen, J Childress, M Chotard, N Copin, Y Fagrelius, P Feindt, U Fleury, M Fouchez, D Gangler, E Hayden, B Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Leget, P-F Lombardo, S Nordin, J Pain, R Pecontal, E Pereira, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Rabinowitz, D Ren, J Rigault, M Rubin, D Runge, K Saunders, C Scalzo, R Smadja, G Sofiatti, C Strovink, M Suzuki, N Tao, C Thomas, RC Weaver, BA https://escholarship.org/uc/item/78p7770f We present our survey for optically faint variable objects using multiepoch (8-10 epochs over 2-4 years) i′-band imaging data obtained with Subaru Suprime-Cam over 0.918 deg2 in the Subaru/XMM-Newton Deep Field (SXDF). We found 1040 optically variable objects by image subtraction for all the combinations of images at different epochs. This is the first statistical sample of variable objects at depths achieved with 8-10 m class telescopes or the Hubble Space Telescope. The detection limit for variable components is i′vari ∼ 25.5 mag. These variable objects were classified into variable stars, supernovae (SNe), and active galactic nuclei (AGNs), based on the optical morphologies, magnitudes, colors, and optical-mid-infrared colors of the host objects, spatial offsets of variable components from the host objects, and light curves. Detection completeness was examined by simulating light curves for periodic and irregular variability. We detected optical variability for 36% ± 2% (51%... https://escholarship.org/uc/item/78p7770f Tue, 9 Jan 2018 00:00:00 +0000 Morokuma, Tomoki Doi, Mamoru Yasuda, Naoki Akiyama, Masayuki Sekiguchi, Kazuhiro Furusawa, Hisanori Ueda, Yoshihiro Totani, Tomonori Oda, Takeshi Nagao, Tohru Kashikawa, Nobunari Murayama, Takashi Ouchi, Masami Watson, Mike G Richmond, Michael W Lidman, Christopher Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 Spadafora, Anthony L Aldering, Greg Wang, Lifan Hook, Isobel M Knop, Rob A https://escholarship.org/uc/item/00x6m3wh We present the discovery and measurements of a gravitationally lensed supernova (SN) behind the galaxy cluster MOO J1014+0038. Based on multi-band Hubble Space Telescope and Very Large Telescope (VLT) photometry of the supernova, and VLT spectroscopy of the host galaxy, we find a 97.5% probability that this SN is a SN Ia, and a 2.5% chance of a CC SN. Our typing algorithm combines the shape and color of the light curve with the expected rates of each SN type in the host galaxy. With a redshift of 2.2216, this is the highest redshift SN Ia discovered with a spectroscopic host-galaxy redshift. A further distinguishing feature is that the lensing cluster, at redshift 1.23, is the most distant to date to have an amplified SN. The SN lies in the middle of the color and light-curve shape distributions found at lower redshift, disfavoring strong evolution to z = 2.22. We estimate an amplification due to gravitational lensing of (1.10 ± 0.23 mag)—compatible with the value estimated from... https://escholarship.org/uc/item/00x6m3wh Fri, 5 Jan 2018 00:00:00 +0000 Rubin, D https://orcid.org/0000-0001-5402-4647 Hayden, B Huang, X Aldering, G Amanullah, R Barbary, K Boone, K Brodwin, M Deustua, SE Dixon, S Eisenhardt, P Fruchter, AS Gonzalez, AH Goobar, A Gupta, RR Hook, I Jee, MJ https://orcid.org/0000-0002-5751-3697 Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Lidman, CE Linder, E Luther, K Nordin, J Pain, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Raha, Z Rigault, M Ruiz-Lapuente, P Saunders, CM Sofiatti, C Spadafora, AL Stanford, SA Stern, D Suzuki, N Williams, SC https://escholarship.org/uc/item/5mw3m0nt We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 ≤ z ≤ 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of the absorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z < 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae. https://escholarship.org/uc/item/5mw3m0nt Thu, 6 Jul 2017 00:00:00 +0000 Garavini, G Folatelli, G Nobili, S Aldering, G Amanullah, R Antilogus, P Astier, P Blanc, G Bronder, T Burns, MS Conley, A Deustua, SE Doi, M Fabbro, S Fadeyev, V https://orcid.org/0000-0003-0154-4328 Gibbons, R Goldhaber, G Goobar, A Groom, DE Hook, I Howell, DA Kashikawa, N Kim, AG https://orcid.org/0000-0001-6315-8743 Kowalski, M Kuznetsova, N Lee, BC Lidman, C Mendez, J Morokuma, T Motohara, K Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Quimby, R Raux, J Regnault, N Ruiz-Lapuente, P Sainton, G Schahmaneche, K Smith, E Spadafora, AL Stanishev, V Thomas, RC Walton, NA Wang, L Wood-Vasey, WM Yasuda, N https://escholarship.org/uc/item/2vx7q9f0 We present VLT FORS1 and FORS2 spectra of 39 candidate high-redshift supernovae that were discovered as part of a cosmological study using type Ia supernovae (SNe Ia) over a wide range of redshifts. From the spectra alone, 20 candidates are spectrally classified as SNe Ia with redshifts ranging from to . Of the remaining 19 candidates, 1 might be a type II supernova and 11 exhibit broad supernova-like spectral features and/or have supernova-like light curves. The candidates were discovered in 8 separate ground-based searches. In those searches in which SNe Ia at were targeted, over 80% of the observed candidates were spectrally classified as SNe Ia. In those searches in which SNe Ia with were targeted, 4 candidates with were spectrally classified as SNe Ia and later followed with ground and space based observatories. We present the spectra of all candidates, including those that could not be spectrally classified as supernova. https://escholarship.org/uc/item/2vx7q9f0 Thu, 6 Jul 2017 00:00:00 +0000 Lidman, C Howell, DA Folatelli, G Garavini, G Nobili, S Aldering, G Amanullah, R Antilogus, P Astier, P Blanc, G Burns, MS Conley, A Deustua, SE Doi, M Ellis, R Fabbro, S Fadeyev, V https://orcid.org/0000-0003-0154-4328 Gibbons, R Goldhaber, G Goobar, A Groom, DE Hook, I Kashikawa, N Kim, AG https://orcid.org/0000-0001-6315-8743 Knop, RA https://orcid.org/0000-0002-3803-1641 Lee, BC Mendez, J Morokuma, T Motohara, K Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Prasad, V Quimby, R Raux, J Regnault, N Ruiz-Lapuente, P Sainton, G Schaefer, BE Schahmaneche, K Smith, E Spadafora, AL Stanishev, V Walton, NA Wang, L Wood-Vasey, WM Yasuda, N https://escholarship.org/uc/item/1119h4f0 We present a measurement of the rate of distant Type Ia supernovae derived using four large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 deg2, 38 supernovae were detected at redshifts 0.25-0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean redshift z ≃ 0.55 of 1.53 × 10-4 h3 Mpc-3 yr-1 or 0.58 h2 SNu (1 SNu = 1 supernova per century per 1010 LB☉), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models. https://escholarship.org/uc/item/1119h4f0 Thu, 6 Jul 2017 00:00:00 +0000 Pain, R Fabbro, S Sullivan, M Ellis, RS Aldering, G Astier, P Deustua, SE Fruchter, AS Goldhaber, G Goobar, A Groom, DE Hardin, D Hook, IM Howell, DA Irwin, MJ Kim, AG https://orcid.org/0000-0001-6315-8743 Kim, MY Knop, RA https://orcid.org/0000-0002-3803-1641 Lee, JC Lidman, C McMahon, RG Nugent, PE https://orcid.org/0000-0002-3389-0586 Panagia, N Pennypacker, CR Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ruiz-Lapuente, P Schahmaneche, K Schaefer, B Walton, NA https://escholarship.org/uc/item/8qz0b7p9 We present a method for selecting high-redshift Type Ia supernovae (SNe Ia) located via rolling SN searches. The technique, using both color and magnitude information of events from only two to three epochs of multiband real-time photometry, is able to discriminate between SNe Ia and core-collapse SNe. Furthermore, for SNe Ia the method accurately predicts the redshift, phase, and light-curve parameterization of these events based only on pre-maximum-light data. We demonstrate the effectiveness of the technique on a simulated survey of SNe Ia and core-collapse SNe, where the selection method effectively rejects most core-collapse SNe while retaining SNe Ia. We also apply the selection code to real-time data acquired as part of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). During the period 2004 May to 2005 January in the SNLS, 440 SN candidates were discovered, of which 70 were confirmed spectroscopically as SNe Ia and 15 as core-collapse events. For this... https://escholarship.org/uc/item/8qz0b7p9 Fri, 13 Jan 2017 00:00:00 +0000 Sullivan, M Howell, DA Perrett, K Nugent, PE https://orcid.org/0000-0002-3389-0586 Astier, P Aubourg, E Balam, D Basa, S Carlberg, RG Conley, A Fabbro, S Fouchez, D Guy, J https://orcid.org/0000-0001-9822-6793 Hook, I Lafoux, H Neill, JD Pain, R Palanque-Delabrouille, N Pritchet, CJ Regnault, N Rich, J Taillet, R Aldering, G Baumont, S Bronder, J Filiol, M Knop, RA https://orcid.org/0000-0002-3803-1641 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Tao, C https://escholarship.org/uc/item/8646z73c We present a new compilation of Type Ia supernovae (SNe Ia), a new data set of low-redshift nearby-Hubble-flow SNe, and new analysis procedures to work with these heterogeneous compilations. This “Union” compilation of 414 SNe Ia, which reduces to 307 SNe after selection cuts, includes the recent large samples of SNe Ia from the Supernova Legacy Survey and ESSENCE Survey, the older data sets, as well as the recently extended data set of distant supernovae observed with the Hubble Space Telescope (HST). A single, consistent, and blind analysis procedure is used for all the various SN Ia subsamples, and a new procedure is implemented that consistently weights the heterogeneous data sets and rejects outliers. We present the latest results from this Union compilation and discuss the cosmological constraints from this new compilation and its combination with other cosmological measurements (CMB and BAO). The constraint we obtain from supernovae on the dark energy density is ΩΛ = 0.713+... https://escholarship.org/uc/item/8646z73c Fri, 13 Jan 2017 00:00:00 +0000 Kowalski, M Rubin, D Aldering, G Agostinho, RJ Amadon, A Amanullah, R Balland, C Barbary, K Blanc, G Challis, PJ Conley, A Connolly, NV Covarrubias, R Dawson, KS Deustua, SE Ellis, R Fabbro, S Fadeyev, V https://orcid.org/0000-0003-0154-4328 Fan, X Farris, B Folatelli, G Frye, BL Garavini, G Gates, EL https://orcid.org/0000-0002-3739-0423 Germany, L Goldhaber, G Goldman, B Goobar, A Groom, DE Haissinski, J Hardin, D Hook, I Kent, S Kim, AG https://orcid.org/0000-0001-6315-8743 Knop, RA https://orcid.org/0000-0002-3803-1641 Lidman, C Linder, EV Mendez, J Meyers, J Miller, GJ Moniez, M Mourão, AM Newberg, H Nobili, S Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Perdereau, O Perlmutter, S https://orcid.org/0000-0002-4436-4661 Phillips, MM Prasad, V Quimby, R Regnault, N Rich, J Rubenstein, EP Ruiz-Lapuente, P Santos, FD Schaefer, BE Schommer, RA Smith, RC Soderberg, AM Spadafora, AL Strolger, L-G Strovink, M Suntzeff, NB Suzuki, N Thomas, RC Walton, NA Wang, L Wood-Vasey, WM Yun, JL https://escholarship.org/uc/item/81w8w1qb We report measurements of ΩM, ΩΛ, and w from 11 supernovae (SNe) at z = 0.36-0.86 with high-quality light curves measured using WFPC2 on the Hubble Space Telescope (HST). This is an independent set of high-redshift SNe that confirms previous SN evidence for an accelerating universe. The high-quality light curves available from photometry on WFPC2 make it possible for these 11 SNe alone to provide measurements of the cosmological parameters comparable in statistical weight to the previous results. Combined with earlier Supernova Cosmology Project data, the new SNe yield a measurement of the mass density ΩM = 0.25 (statistical) ± 0.04 (identified systematics), or equivalently, a cosmological constant of ΩΛ = 0.75 (statistical) ± 0.04 (identified systematics), under the assumptions of a flat universe and that the dark energy equation-of-state parameter has a constant value w = -1. When the SN results are combined with independent flat-universe measurements of ΩM from cosmic microwave... https://escholarship.org/uc/item/81w8w1qb Fri, 13 Jan 2017 00:00:00 +0000 Knop, RA https://orcid.org/0000-0002-3803-1641 Aldering, G Amanullah, R Astier, P Blanc, G Burns, MS Conley, A Deustua, SE Doi, M Ellis, R Fabbro, S Folatelli, G Fruchter, AS Garavini, G Garmond, S Garton, K Gibbons, R Goldhaber, G Goobar, A Groom, DE Hardin, D Hook, I Howell, DA Kim, AG https://orcid.org/0000-0001-6315-8743 Lee, BC Lidman, C Mendez, J Nobili, S Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Panagia, N Pennypacker, CR Perlmutter, S https://orcid.org/0000-0002-4436-4661 Quimby, R Raux, J Regnault, N Ruiz-Lapuente, P Sainton, G Schaefer, B Schahmaneche, K Smith, E Spadafora, AL Stanishev, V Sullivan, M Walton, NA Wang, L Wood-Vasey, WM Yasuda, N https://escholarship.org/uc/item/4mv1h6vn We have obtained high-quality Keck optical spectra at three epochs of the Type Ia supernova 1997ex, whose redshift z is 0.361. The elapsed calendar time between the first two spectra was 24.88 days, and that between the first and third spectra was 30.95 days. In an expanding universe where 1 + z represents the factor by which space has expanded between the emission and detection of light, the amount of aging in the supernova rest frame should be a factor of 1/(1 + z) smaller than the observed-frame aging; thus, we expect SN 1997ex to have aged 18.28 and 22.74 days between the first epoch and the second and third epochs, respectively. The quantitative method for determining the spectral-feature age of an SN Ia reveals that the corresponding elapsed times in the supernova rest frame were 16.97 ± 2.75 and 18.01 ± 3.14 days, respectively. This result is inconsistent with no time dilation with a significance level of 99.0%, providing evidence against "tired light" and other hypotheses... https://escholarship.org/uc/item/4mv1h6vn Fri, 13 Jan 2017 00:00:00 +0000 Foley, Ryan J https://orcid.org/0000-0002-2445-5275 Filippenko, Alexei V https://orcid.org/0000-0003-3460-0103 Leonard, Douglas C Riess, Adam G Nugent, Peter https://orcid.org/0000-0002-3389-0586 Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 https://escholarship.org/uc/item/4581m41c We present new results on the Hubble diagram of distant type Ia supernovae (SNe Ia) segregated according to the type of host galaxy. This makes it possible to check earlier evidence for a cosmological constant by explicitly comparing SNe residing in galaxies likely to contain negligible dust with the larger sample. The cosmological parameters derived from these SNe Ia hosted by presumed dust-free early-type galaxies support earlier claims for a cosmological constant, which we demonstrate at ≃5σ significance, and the internal extinction implied is small even for late-type systems (AB < 0.2). Thus, our data demonstrate that host galaxy extinction is unlikely to systematically dim distant SNe Ia in a manner that would produce a spurious cosmological constant. Our analysis is based on new Hubble Space Telescope STIS ‘snapshot’ images and Keck-II echellette spectroscopy at the locations of the SNe, spanning the redshift range 0 < z < 0.8. Selecting from the sample discovered... https://escholarship.org/uc/item/4581m41c Fri, 13 Jan 2017 00:00:00 +0000 Sullivan, M Ellis, RS Aldering, G Amanullah, R Astier, P Blanc, G Burns, MS Conley, A Deustua, SE Doi, M Fabbro, S Folatelli, G Fruchter, AS Garavini, G Gibbons, R Goldhaber, G Goobar, A Groom, DE Hardin, D Hook, I Howell, DA Irwin, M Kim, AG https://orcid.org/0000-0001-6315-8743 Knop, RA https://orcid.org/0000-0002-3803-1641 Lidman, C McMahon, R Mendez, J Nobili, S Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Panagia, N Pennypacker, CR Perlmutter, S https://orcid.org/0000-0002-4436-4661 Quimby, R Raux, J Regnault, N Ruiz-Lapuente, P Schaefer, B Schahmaneche, K Spadafora, AL Walton, NA Wang, L Wood-Vasey, WM Yasuda, N https://escholarship.org/uc/item/44s4553m We present measurements of Ωm and ΩΛ from a blind analysis of 21 high-redshift supernovae using a new technique (CMAGIC) for fitting the multicolor light curves of Type Ia supernovae, first introduced by Wang and coworkers. CMAGIC takes advantage of the remarkably simple behavior of Type Ia supernovae on color-magnitude diagrams and has several advantages over current techniques based on maximum magnitudes. Among these are a reduced sensitivity to host galaxy dust extinction, a shallower luminosity-width relation, and the relative simplicity of the fitting procedure. This allows us to provide a cross-check of previous supernova cosmology results, despite the fact that current data sets were not observed in a manner optimized for CMAGIC. We describe the details of our novel blindness procedure, which is designed to prevent experimenter bias. The data are broadly consistent with the picture of an accelerating universe and agree with a flat universe within 1.7 σ, including systematics.... https://escholarship.org/uc/item/44s4553m Fri, 13 Jan 2017 00:00:00 +0000 Conley, A Goldhaber, G Wang, L Aldering, G Amanullah, R Commins, ED Fadeyev, V https://orcid.org/0000-0003-0154-4328 Folatelli, G Garavini, G Gibbons, R Goobar, A Groom, DE Hook, I Howell, DA Kim, AG https://orcid.org/0000-0001-6315-8743 Knop, RA https://orcid.org/0000-0002-3803-1641 Kowalski, M Kuznetsova, N Lidman, C Nobili, S Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Smith, E Spadafora, AL Stanishev, V Strovink, M Thomas, RC Wood-Vasey, WM https://escholarship.org/uc/item/3xr6s8h4 The recent robust and homogeneous analysis of the world's supernova distance–redshift data, together with cosmic microwave background and baryon acoustic oscillation data—provides a powerful tool for constraining cosmological models. Here we examine particular classes of scalar field, modified gravity, and phenomenological models to assess whether they are consistent with observations even when their behavior deviates from the cosmological constant Λ. Some models have tension with the data, while others survive only by approaching the cosmological constant, and a couple are statistically favored over Λ cold dark matter. Dark energy described by two equation-of-state parameters has considerable phase space to avoid Λ and next-generation data will be required to constrain such physics, with the level of complementarity between probes varying with cosmology. https://escholarship.org/uc/item/3xr6s8h4 Fri, 13 Jan 2017 00:00:00 +0000 Rubin, D Linder, EV Kowalski, M Aldering, G Amanullah, R Barbary, K Connolly, NV Dawson, KS Faccioli, L Fadeyev, V https://orcid.org/0000-0003-0154-4328 Goldhaber, G Goobar, A Hook, I Lidman, C Meyers, J Nobili, S Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ruiz-Lapuente, P Spadafora, AL Strovink, M Suzuki, N Swift, H https://escholarship.org/uc/item/3cn227qn High-quality spectropolarimetry (range 417-860 nm; spectral resolution 1.27 nm and 0.265 nm pixel-1) of the Type Ia supernova (SN Ia) 2001el was obtained with the ESO Very Large Telescope Melipal (+FORS1) at five epochs. The spectra a week before maximum and around maximum indicate photospheric expansion velocities of about 10,000 km s-1. Prior to optical maximum, the linear polarization of the continuum was ≈0.2%-0.3% with a constant position angle, showing that SN 2001el has a well-defined axis of symmetry. The polarization was nearly undetectable a week after optical maximum. The spectra are similar to those of the normally bright SN 1994D, with the exception of a strong double-troughed absorption feature seen around 800 nm (FWHM about 22 nm). The 800 nm feature is probably due to the Ca II IR triplet at very high velocities (20,000-26,000 km s-1) involving ~0.004 M☉ of calcium and perhaps 0.1 M☉ total mass. The 800 nm feature is distinct in velocity space from the photospheric... https://escholarship.org/uc/item/3cn227qn Fri, 13 Jan 2017 00:00:00 +0000 Wang, Lifan Baade, Dietrich Höflich, Peter Khokhlov, Alexei Wheeler, J Craig Kasen, D Nugent, Peter E https://orcid.org/0000-0002-3389-0586 Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 Fransson, Claes Lundqvist, Peter https://escholarship.org/uc/item/2r95z5rn We present spectra for 14 high-redshift (0.17 < z < 0.83) supernovae, which were discovered by the Supernova Cosmology Project as part of a campaign to measure cosmological parameters. The spectra are used to determine the redshift and classify the supernova type, essential information if the supernovae are to be used for cosmological studies. Redshifts were derived either from the spectrum of the host galaxy or from the spectrum of the supernova itself. We present evidence that these supernovae are of Type Ia (SNe Ia) by matching to spectra of nearby supernovae. We find that the dates of the spectra relative to maximum light determined from this fitting process are consistent with the dates determined from the photometric light curves, and, moreover, the spectral time sequences for SNe Ia at low and high redshift are indistinguishable. We also show that the expansion velocities measured from blueshifted Ca H and K are consistent with those measured for low-redshift SNe... https://escholarship.org/uc/item/2r95z5rn Fri, 13 Jan 2017 00:00:00 +0000 Hook, IM Howell, DA Aldering, G Amanullah, R Burns, MS Conley, A Deustua, SE Ellis, R Fabbro, S Fadeyev, V https://orcid.org/0000-0003-0154-4328 Folatelli, G Garavini, G Gibbons, R Goldhaber, G Goobar, A Groom, DE Kim, AG https://orcid.org/0000-0001-6315-8743 Knop, RA https://orcid.org/0000-0002-3803-1641 Kowalski, M Lidman, C Nobili, S Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Pennypacker, CR Perlmutter, S https://orcid.org/0000-0002-4436-4661 Ruiz-Lapuente, P Sainton, G Schaefer, BE Smith, E Spadafora, AL Stanishev, V Thomas, RC Walton, NA Wang, L Wood-Vasey, WM https://escholarship.org/uc/item/08h7h712 We present a novel technique for fitting restframe I-band light curves on a data set of 42 type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at . Adding two SNe at yields results consistent with a flat Λ-dominated “concordance universe” () = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe Ia as distance estimators. A flat, , universe where the faintness of supernovae at is due to grey dust homogeneously distributed in the intergalactic medium is disfavoured based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on and colour measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results.... https://escholarship.org/uc/item/08h7h712 Fri, 13 Jan 2017 00:00:00 +0000 Nobili, S Amanullah, R Garavini, G Goobar, A Lidman, C Stanishev, V Aldering, G Antilogus, P Astier, P Burns, MS Conley, A Deustua, SE Ellis, R Fabbro, S Fadeyev, V https://orcid.org/0000-0003-0154-4328 Folatelli, G Gibbons, R Goldhaber, G Groom, DE Hook, I Howell, DA Kim, AG https://orcid.org/0000-0001-6315-8743 Knop, RA https://orcid.org/0000-0002-3803-1641 Nugent, PE https://orcid.org/0000-0002-3389-0586 Pain, R Perlmutter, S https://orcid.org/0000-0002-4436-4661 Quimby, R Raux, J Regnault, N Ruiz-Lapuente, P Sainton, G Schahmaneche, K Smith, E Spadafora, AL Thomas, RC Wang, L https://escholarship.org/uc/item/9k9027m0 We report measurements of the mass density, ΩM, and cosmological-constant energy density, ΩΛ, of the universe based on the analysis of 42 type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fitted jointly with a set of supernovae from the Calán/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. All supernova peak magnitudes are standardized using a SN Ia light-curve width-luminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation 0.8ΩM-0.6ΩΛ≈-0.2±0.1 in the region of interest (ΩM≲1.5). For a flat (ΩM+ΩΛ=1) cosmology we find ΩMflat=0.28+0.09-0.08 (1 σ statistical) +0.05-0.04 (identified systematics). The data are strongly inconsistent with a Λ=0 flat cosmology, the simplest inflationary universe model. An open, Λ=0 cosmology also does not fit the... https://escholarship.org/uc/item/9k9027m0 Wed, 11 Jan 2017 00:00:00 +0000 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Aldering, G Goldhaber, G Knop, RA Nugent, P https://orcid.org/0000-0002-3389-0586 Castro, PG Deustua, S Fabbro, S Goobar, A Groom, DE Hook, IM Kim, AG https://orcid.org/0000-0001-6315-8743 Kim, MY Lee, JC Nunes, NJ Pain, R Pennypacker, CR Quimby, R Lidman, C Ellis, RS Irwin, M McMahon, RG Ruiz-Lapuente, P Walton, N Schaefer, B Boyle, BJ Filippenko, AV Matheson, T Fruchter, AS Panagia, N Newberg, HJM Couch, WJ Project, The Supernova Cosmology https://escholarship.org/uc/item/92r7x51m SN 1999aw was discovered during the first campaign of the Nearby Galaxies Supernova Search project. This luminous, slow-declining [Δm15(B) = 0.81 ± 0.03] Type Ia supernova was noteworthy in at least two respects. First, it occurred in an extremely low luminosity host galaxy that was not visible in the template images nor in initial subsequent deep imaging. Second, the photometric and spectral properties of this supernova indicate that it very likely was similar to the subclass of Type Ia supernovae whose prototype is SN 1999aa. This paper presents the BVRI and JsHKs light curves of SN 1999aw (through ∼100 days past maximum light), as well as several epochs of optical spectra. From these data, we calculate the bolometric light curve and give estimates of the luminosity at maximum light and the initial 56Ni mass. In addition, we present deep BVI images obtained recently with the Baade 6.5 m telescope at Las Campanas Observatory that reveal the remarkably low-luminosity host galaxy. https://escholarship.org/uc/item/92r7x51m Wed, 11 Jan 2017 00:00:00 +0000 Strolger, L-G Smith, RC Suntzeff, NB Phillips, MM Aldering, G Nugent, P https://orcid.org/0000-0002-3389-0586 Knop, R https://orcid.org/0000-0002-3803-1641 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Schommer, RA Ho, LC Hamuy, M Krisciunas, K Germany, LM Covarrubias, R Candia, P Athey, A Blanc, G Bonacic, A Bowers, T Conley, A Dahlén, T Freedman, W Galaz, G Gates, E https://orcid.org/0000-0002-3739-0423 Goldhaber, G Goobar, A Groom, D Hook, IM Marzke, R Mateo, M McCarthy, P Méndez, J Muena, C Persson, SE Quimby, R Roth, M Ruiz-Lapuente, P Seguel, J Szentgyorgyi, A von Braun, K Wood-Vasey, WM York, T https://escholarship.org/uc/item/8zj3k1fx We present an empirical method that measures the distance to a Type Ia supernova (SN Ia) with a precision of ~10% from a single night's data. This method measures the supernova's age and luminosity/light-curve parameter from a spectrum and the extinction and distance from an apparent magnitude and color. We are able to verify the precision of this method from error propagation calculations, Monte Carlo simulations of well-sampled SNe Ia, and the Hubble diagram of sparsely observed supernovae. With the reduction in telescope time needed, this method is 3-4 times more efficient for measuring cosmological parameters than conventional light-curve-based distance estimates. https://escholarship.org/uc/item/8zj3k1fx Wed, 11 Jan 2017 00:00:00 +0000 Riess, Adam G Nugent, Peter https://orcid.org/0000-0002-3389-0586 Filippenko, Alexei V https://orcid.org/0000-0003-3460-0103 Kirshner, Robert P Perlmutter, Saul https://orcid.org/0000-0002-4436-4661 https://escholarship.org/uc/item/4zr2h0zq The ultimate fate of the Universe, infinite expansion or a big crunch, can be determined by using the redshifts and distances of very distant supernovae to monitor changes in the expansion rate. We can now find1 large numbers of these distant supernovae, and measure their redshifts and apparent brightnesses; moreover, recent studies of nearby type Ia supernovae have shown how to determine their intrinsic luminosities2,3,4—and therefore with their apparent brightnesses obtain their distances. The >50 distant supernovae discovered so far provide a record of changes in the expansion rate over the past several billion years5,6,7. However, it is necessary to extend this expansion history still farther away (hence further back in time) in order to begin to distinguish the causes of the expansion-rate changes—such as the slowing caused by the gravitational attraction of the Universe's mass density, and the possibly counteracting effect of the cosmological constant8. Here we report... https://escholarship.org/uc/item/4zr2h0zq Wed, 11 Jan 2017 00:00:00 +0000 Perlmutter, S https://orcid.org/0000-0002-4436-4661 Aldering, G Valle, M Della Deustua, S Ellis, RS Fabbro, S Fruchter, A Goldhaber, G Groom, DE Hook, IM Kim, AG https://orcid.org/0000-0001-6315-8743 Kim, MY Knop, RA https://orcid.org/0000-0002-3803-1641 Lidman, C McMahon, RG Nugent, P https://orcid.org/0000-0002-3389-0586 Pain, R Panagia, N Pennypacker, CR Ruiz-Lapuente, P Schaefer, B Walton, N