- ID:
- ivo://CDS.VizieR/J/AJ/142/156
- Title:
- The CSP (DR2): photometry of SNe Ia
- Short Name:
- J/AJ/142/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri) bandpasses with an accuracy of ~1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/874/150
- Title:
- The first 3yrs of DES-SN (DES-SN3YR)
- Short Name:
- J/ApJ/874/150
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We present the analysis underpinning the measurement of cosmological parameters from 207 spectroscopically classified SNe Ia from the first 3 years of the Dark Energy Survey Supernova Program (DES-SN), spanning a redshift range of 0.017<z<0.849. We combine the DES-SN sample with an external sample of 122 low-redshift (z<0.1) SNe Ia, resulting in a "DES-SN3YR" sample of 329 SNe Ia. Our cosmological analyses are blinded: after combining our DES-SN3YR distances with constraints from the Cosmic Microwave Background, our uncertainties in the measurement of the dark energy equation-of-state parameter, w, are 0.042 (stat) and 0.059 (stat+syst) at 68% confidence. We provide a detailed systematic uncertainty budget, which has nearly equal contributions from photometric calibration, astrophysical bias corrections, and instrumental bias corrections. We also include several new sources of systematic uncertainty. While our sample is less than one-third the size of the Pantheon sample, our constraints on w are only larger by 1.4x, showing the impact of the DES-SN Ia light-curve quality. We find that the traditional stretch and color standardization parameters of the DES-SNe Ia are in agreement with earlier SN Ia samples such as Pan-STARRS1 and the Supernova Legacy Survey. However, we find smaller intrinsic scatter about the Hubble diagram (0.077mag). Interestingly, we find no evidence for a Hubble residual step (0.007+/-0.018mag) as a function of host-galaxy mass for the DES subset, in 2.4{sigma} tension with previous measurements. We also present novel validation methods of our sample using simulated SNe Ia inserted in DECam images and using large catalog-level simulations to test for biases in our analysis pipelines.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/85
- Title:
- THe HST Cluster Supernova Survey. V.
- Short Name:
- J/ApJ/746/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Advanced Camera for Surveys, NICMOS, and Keck adaptive-optics-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the Hubble Space Telescope (HST) Cluster Supernova Survey. The SNe Ia were discovered over the redshift interval 0.623<z<1.415. Of these SNe Ia, 14 pass our strict selection cuts and are used in combination with the world's sample of SNe Ia to derive the best current constraints on dark energy. Of our new SNe Ia, 10 are beyond redshift z = 1, thereby nearly doubling the statistical weight of HST-discovered SNe Ia beyond this redshift. Our detailed analysis corrects for the recently identified correlation between SN Ia luminosity and host galaxy mass and corrects the NICMOS zero point at the count rates appropriate for very distant SNe Ia. Adding these SNe improves the best combined constraint on dark-energy density, {rho}_DE_(z), at redshifts 1.0<z<1.6 by 18% (including systematic errors).
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3895
- Title:
- The rising light curves of Type Ia supernovae
- Short Name:
- J/MNRAS/446/3895
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the early, rising light curves of 18 Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory and the La Silla-QUEST variability survey. We fit these early data flux using a simple power law (f(t)={alpha}xt^n^) to determine the time of first light (t_0_), and hence the rise time (t_rise_) from first light to peak luminosity, and the exponent of the power-law rise (n). We find a mean uncorrected rise time of 18.98+/-0.54 d, with individual supernova (SN) rise times ranging from 15.98 to 24.7 d. The exponent n shows significant departures from the simple `fireball model' of n=2 (or f(t){prop.to}t^2^) usually assumed in the literature. With a mean value of n=2.44+/-0.13, our data also show significant diversity from event to event. This deviation has implications for the distribution of ^56^Ni throughout the SN ejecta, with a higher index suggesting a lesser degree of ^56^Ni mixing. The range of n found also confirms that the ^56^Ni distribution is not standard throughout the population of SNe Ia, in agreement with earlier work measuring such abundances through spectral modelling. We also show that the duration of the very early light curve, before the luminosity has reached half of its maximal value, does not correlate with the light-curve shape or stretch used to standardize SNe Ia in cosmological applications. This has implications for the cosmological fitting of SN Ia light curves.
- ID:
- ivo://CDS.VizieR/J/A+A/636/A46
- Title:
- The SUGAR model. Training dataset
- Short Name:
- J/A+A/636/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This analysis 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. 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 data taken at different epochs during the lifetime of an SN Ia and then projecting the data on a fixed time grid. Finally, the three steps were combined to build the SED model as a function of time and wavelength. This is the SUGAR model. The proper way to cite the data can be found at https://snfactory.lbl.gov/snf/data/index.html
- ID:
- ivo://CDS.VizieR/J/ApJ/859/101
- Title:
- The supernovae Ia Pantheon sample
- Short Name:
- J/ApJ/859/101
- Date:
- 20 Jan 2022 07:41:10
- Publisher:
- CDS
- Description:
- We present optical light curves, redshifts, and classifications for 365 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. We detail improvements to the PS1 SN photometry, astrometry, and calibration that reduce the systematic uncertainties in the PS1 SN Ia distances. We combine the subset of 279 PS1 SNe Ia (0.03<z<0.68) with useful distance estimates of SNe Ia from the Sloan Digital Sky Survey (SDSS), SNLS, and various low-z and Hubble Space Telescope samples to form the largest combined sample of SNe Ia, consisting of a total of 1048 SNe Ia in the range of 0.01<z<2.3, which we call the "Pantheon Sample". When combining Planck 2015 cosmic microwave background (CMB) measurements with the Pantheon SN sample, we find {Omega}_m_=0.307+/-0.012 and w=-1.026+/-0.041 for the wCDM model. When the SN and CMB constraints are combined with constraints from BAO and local H_0_ measurements, the analysis yields the most precise measurement of dark energy to date: w_0_=-1.007+/-0.089 and w_a_=-0.222+/-0.407 for the w_0_w_a_CDM model. Tension with a cosmological constant previously seen in an analysis of PS1 and low-z SNe has diminished after an increase of 2x in the statistics of the PS1 sample, improved calibration and photometry, and stricter light-curve quality cuts. We find that the systematic uncertainties in our measurements of dark energy are almost as large as the statistical uncertainties, primarily due to limitations of modeling the low-redshift sample. This must be addressed for future progress in using SNe Ia to measure dark energy.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A147
- Title:
- Transient processing and analysis using AMPEL
- Short Name:
- J/A+A/631/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Both multi-messenger astronomy and new high-throughput wide-field surveys require flexible tools for the selection and analysis of astrophysical transients. Here we introduce the alert management, photometry, and evaluation of light curves (AMPEL) system, an analysis framework designed for high-throughput surveys and suited for streamed data. AMPEL combines the functionality of an alert broker with a generic framework capable of hosting user-contributed code; it encourages provenance and keeps track of the varying information states that a transient displays. The latter concept includes information gathered over time and data policies such as access or calibration levels. We describe a novel ongoing real-time multi-messenger analysis using AMPEL to combine IceCube neutrino data with the alert streams of the Zwicky Transient Facility (ZTF). We also reprocess the first four months of ZTF public alerts, and compare the yields of more than 200 different transient selection functions to quantify efficiencies for selecting Type Ia supernovae that were reported to the Transient Name Server (TNS). We highlight three channels suitable for (1) the collection of a complete sample of extragalactic transients, (2) immediate follow-up of nearby transients, and (3) follow-up campaigns targeting young, extragalactic transients. We confirm ZTF completeness in that all TNS supernovae positioned on active CCD regions were detected. AMPEL can assist in filtering transients in real time, running alert reaction simulations, the reprocessing of full datasets as well as in the final scientific analysis of transient data. This is made possible by a novel way of capturing transient information through sequences of evolving states, and interfaces that allow new code to be natively applied to a full stream of alerts. This text also introduces a method by which users can design their own channels for inclusion in the AMPEL live instance that parses the ZTF stream and the real-time submission of high-quality extragalactic supernova candidates to the TNS.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A37
- Title:
- TURTLS Light curves of ^56^Ni distributions
- Short Name:
- J/A+A/634/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies have shown how the distribution of ^56^Ni within the ejected material of type Ia supernovae can have profound consequences on the observed light curves. Observations at early times can therefore provide important details on the explosion physics in thermonuclear supernovae, which are poorly constrained. To this end, we present a series of radiative transfer calculations that explore variations in the ^56^Ni distribution. Our models also show the importance of the density profile in shaping the light curve, which is often neglected in the literature. Using our model set, we investigate the observations that are necessary to determine the 56Ni distribution as robustly as possible within the current model set. Additionally, we find that this includes observations beginning at least 14 days before B-band maximum, extending to approximately maximum light with a relatively high (<~3 day) cadence, and in at least one blue and one red band are required (such as B and R, or g and r). We compare a number of well-observed type Ia supernovae that meet these criteria to our models and find that the light curves of 70-80% of objects in our sample are consistent with being produced solely by variations in the ^56^Ni distributions. The remaining supernovae show an excess of flux at early times, indicating missing physics that is not accounted for within our model set, such as an interaction or the presence of short-lived radioactive isotopes. Comparing our model light curves and spectra to observations and delayed detonation models demonstrates that while a somewhat extended ^56^Ni distribution is necessary to reproduce the observed light curve shape, this does not negatively affect the spectra at maximum light. Investigating current explosion models shows that observations typically require a shallower decrease in the ^56^Ni mass towards the outer ejecta than is produced for models of a given ^56^Ni mass. Future models that test differences in the explosion physics and detonation criteria should be explored to determine the conditions necessary to reproduce the 56Ni distributions found here.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/732
- Title:
- Type Ia SN environment within host galaxies
- Short Name:
- J/MNRAS/448/732
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present constraints on Type Ia supernovae (SNe Ia) progenitors through an analysis of the environments found at the explosion sites of 102 events within star-forming host galaxies. H{alpha} and Galaxy Evolution Explorer near-ultraviolet (UV) images are used to trace on-going and recent star formation (SF), while broad-band B, R, J, K imaging is also analysed. Using pixel statistics we find that SNe Ia show the lowest degree of association with H{alpha} emission of all supernova (SN) types. It is also found that they do not trace near-UV emission. As the latter traces SF on time-scales less than 100Myr, this rules out any extreme 'prompt' delay times as the dominant progenitor channel of SNe Ia. SNe Ia best trace the B-band light distribution of their host galaxies. This implies that the population within star-forming galaxies is dominated by relatively young progenitors. Splitting SNe by their (B-V) colours at maximum light, 'redder' events show a higher degree of association with HII regions and are found more centrally within hosts. We discuss possible explanations of this result in terms of line-of-sight extinction and progenitor effects. No evidence for correlations between SN stretch and environment properties is observed.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/53
- Title:
- Type Ia SNe spectroscopy by the CSP
- Short Name:
- J/ApJ/773/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of {approx}0.15mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a {approx}2{sigma}-3{sigma} correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.
