- ID:
- ivo://CDS.VizieR/J/MNRAS/389/1871
- Title:
- Type Ia supernovae candidates from SDSS
- Short Name:
- J/MNRAS/389/1871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of the surveyed area was observed more than once due to field tiling overlap, usually at different epochs. We utilize some of these data to perform a supernova (SN) survey at a mean redshift of z=0.2. Our archival search, in ~5 per cent of the SDSS-I overlap area, produces 29 SN candidates clearly associated with host galaxies. Using the Bayesian photometric classification algorithm of Poznanski et al. (2002PASP..114..833P), and correcting for classification bias, we find 17 of the 29 candidates are likely Type Ia SNe.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/1973
- Title:
- Type Ia supernovae igh-velocity features
- Short Name:
- J/MNRAS/451/1973
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 'High-velocity features' (HVFs) are spectral features in Type Ia supernovae (SNe Ia) that have minima indicating significantly higher (by greater than about 6000km/s) velocities than typical 'photospheric-velocity features' (PVFs). The PVFs are absorption features with minima indicating typical photospheric (i.e. bulk ejecta) velocities (usually~9000-15000km/s near B-band maximum brightness). In this work, we undertake the most in-depth study of HVFs ever performed. The data set used herein consists of 445 low-resolution optical and near-infrared (NIR) spectra (at epochs up to 5d past maximum brightness) of 210 low-redshift SNe Ia that follow the 'Phillips relation'. A series of Gaussian functions is fit to the data in order to characterize possible HVFs of CaII H&K, SiII {lambda}6355, and the CaII NIR triplet. The temporal evolution of the velocities and strengths of the PVFs and HVFs of these three spectral features is investigated, as are possible correlations with other SN Ia observables. We find that while HVFs of CaII are regularly observed (except in underluminous SNe Ia, where they are never found), HVFs of Siii {lambda}6355 are significantly rarer, and they tend to exist at the earliest epochs and mostly in objects with large photospheric velocities. It is also shown that stronger HVFs of SiII {lambda}6355 are found in objects that lack CII absorption at early times and that have red ultraviolet/optical colours near maximum brightness. These results lead to a self-consistent connection between the presence and strength of HVFs of SiII {lambda}6355 and many other mutually correlated SN Ia observables, including photospheric velocity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/782
- Title:
- Type Ia supernovae luminosities
- Short Name:
- J/MNRAS/406/782
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precision cosmology with Type Ia supernovae (SNe Ia) makes use of the fact that SN Ia luminosities depend on their light-curve shapes and colours. Using Supernova Legacy Survey (SNLS) and other data, we show that there is an additional dependence on the global characteristics of their host galaxies: events of the same light-curve shape and colour are, on average, 0.08mag (~4.0{sigma}) brighter in massive host galaxies (presumably metal-rich) and galaxies with low specific star formation rates (sSFR).
- ID:
- ivo://CDS.VizieR/J/A+A/615/A68
- Title:
- Type Ia supernova luminosities
- Short Name:
- J/A+A/615/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a fully consistent catalog of local and global properties of host galaxies of 882 Type Ia supernovae (SNIa) that were selected based on their light-curve properties, spanning the redshift range 0.01<z<1. This catalog corresponds to a preliminary version of the compilation sample and includes Supernova Legacy Survey (SNLS) 5-year data, Sloan Digital Sky Survey (SDSS), and low-redshift surveys. We measured low- and moderate-redshift host galaxy photometry in SDSS stacked and single-epoch images and used spectral energy distribution (SED) fitting techniques to derive host properties such as stellar mass and U-V rest-frame colors; the latter are an indicator of the luminosity-weighted age of the stellar population in a galaxy. We combined these results with high-redshift host photometry from the SNLS survey and thus obtained a consistent catalog of host stellar masses and colors across a wide redshift range. We also estimated the local observed fluxes at the supernova location within a proper distance radius of 3kpc, corresponding to the SNLS imaging resolution, and transposed them into local U-V rest-frame colors. This is the first time that local environments surrounding SNIa have been measured at redshifts spanning the entire Hubble diagram. Selecting SNIa based on host photometry quality, we then performed cosmological fits using local color as a third standardization variable, for which we split the sample at the median value. We find a local color step significance of -0.091+/-0.013mag (7{sigma}), which effect is as significant as the maximum mass step effect. This indicates that the remaining luminosity variations in SNIa samples can be reduced with a third standardization variable that takes the environment into account. Correcting for the maximum mass step correction of -0.094+/-0.013mag, we find a local color effect of -0.057+/-0.012mag (5{sigma}), which shows that additional information is provided by the close environment of SNIa. Departures from the initial choices were investigated and showed that the local color effect is still present, although less pronounced. We discuss the possible implications for cosmology and find that using the local color in place of the stellar mass results in a change in the measured value of the dark energy equation-of-state parameter of 0.6%. Standardization using local U-V color in addition to stretch and color reduces the total dispersion in the Hubble diagram from 0.15 to 0.14mag. This will be of tremendous importance for the forthcoming SNIa surveys, and in particular for the Large Synoptic Survey Telescope (LSST), for which uncertainties on the dark energy equation of state will be comparable to the effects reported here.
- ID:
- ivo://CDS.VizieR/J/ApJ/673/981
- Title:
- Type Ia supernova rates with HST ACS
- Short Name:
- J/ApJ/673/981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new measurement of the volumetric rate of SNe Ia up to a redshift of 1.7, using the HST GOODS data combined with an additional HST data set covering the GOODS-North field collected in 2004. We employ a novel technique that does not require spectroscopic data for identifying SNe Ia (although spectroscopic measurements of redshifts are used for over half the sample); instead, we employ a Bayesian approach using only photometric data to calculate the probability that an object is an SN Ia. This Bayesian technique can easily be modified to incorporate improved priors on SN properties, and it is well-suited for future high-statistics SN searches in which spectroscopic follow-up of all candidates will be impractical. Here the method is validated on both ground- and space-based SN data having some spectroscopic follow-up. We combine our volumetric rate measurements with low-redshift SN data and fit to a number of possible models for the evolution of the SN Ia rate as a function of redshift. The data do not distinguish between a flat rate at redshift >0.5 and a previously proposed model, in which the Type Ia rate peaks at redshift ~1 due to a significant delay from star formation to the SN explosion. Except for the highest redshifts, where the signal-to-noise ratio is generally too low to apply this technique, this approach yields uncertainties that are smaller than or comparable to previous work.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/159
- Title:
- Type Ia supernova SN 2019ein UBVgri photometry
- Short Name:
- J/ApJ/897/159
- Date:
- 16 Mar 2022 00:28:33
- Publisher:
- CDS
- Description:
- We present multiwavelength photometric and spectroscopic observations of SN 2019ein, a high-velocity Type Ia supernova (SNIa) discovered in the nearby galaxy NGC5353 with a two-day nondetection limit. SN 2019ein exhibited some of the highest measured expansion velocities of any SNIa, with a SiII absorption minimum blueshifted by 24000km/s at 14days before peak brightness. More unusually, we observed the emission components of the PCygni profiles to be blueshifted upward of 10000km/s before B-band maximum light. This blueshift, among the highest in a sample of 28 other SNeIa, is greatest at our earliest spectroscopic epoch and subsequently decreases toward maximum light. We discuss possible progenitor systems and explosion mechanisms that could explain these extreme absorption and emission velocities. Radio observations beginning 14days before B-band maximum light yield nondetections at the position of SN2019ein, which rules out symbiotic progenitor systems, most models of fast optically thick accretion winds, and optically thin shells of mass<~10^-6^M{odot} at radii <100au. Comparing our spectra to models and observations of other high-velocity SNeIa, we find that SN2019ein is well fit by a delayed-detonation explosion. We propose that the high emission velocities may be the result of abundance enhancements due to ejecta mixing in an asymmetric explosion, or optical depth effects in the photosphere of the ejecta at early times. These findings may provide evidence for common explosion mechanisms and ejecta geometries among high-velocity SNeIa.
- ID:
- ivo://CDS.VizieR/J/ApJ/717/342
- Title:
- Type Ibc SNe in disturbed galaxies
- Short Name:
- J/ApJ/717/342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the radial locations of 178 core-collapse supernovae (CCSNe) to the R-band and H{alpha} light distributions of their host galaxies. When the galaxies are split into "disturbed" and "undisturbed" categories, a striking difference emerges. The disturbed galaxies have a central excess of CCSNe and this excess is almost completely dominated by supernovae of types Ib, Ic, and Ib/c, whereas type II supernovae dominate in all other environments. The difference cannot easily be explained by metallicity or extinction effects, and thus we propose that this is direct evidence for a stellar initial mass function that is strongly weighted toward high-mass stars, specifically in the central regions of disturbed galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/785/37
- Title:
- Type Ic SN 2010mb optical photometry
- Short Name:
- J/ApJ/785/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our observations of SN 2010mb, a Type Ic supernova (SN) lacking spectroscopic signatures of H and He. SN 2010mb has a slowly declining light curve (LC) (~600 days) that cannot be powered by ^56^Ni/^56^Co radioactivity, the common energy source for Type Ic SNe. We detect signatures of interaction with hydrogen-free circumstellar material including a blue quasi-continuum and, uniquely, narrow oxygen emission lines that require high densities (~10^9^/cm^3^). From the observed spectra and LC, we estimate that the amount of material involved in the interaction was ~3 M_{sun}_. Our observations are in agreement with models of pulsational pair-instability SNe described in the literature.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A73
- Title:
- Type IIn supernova photometry
- Short Name:
- J/A+A/637/A73
- Date:
- 14 Jan 2022 08:08:51
- Publisher:
- CDS
- Description:
- The evolution of a Type IIn supernova (SN IIn) is governed by the interaction between the SN ejecta and a hydrogen-rich circumstellar medium (CSM). SNe IIn thus allow us to probe the late-time mass-loss history of their progenitor stars. We present optical photometry of a sample of 42 Type IIn supernovae, obtained by the Palomar Transient Factory (PTF) collaboration and its successor, the intermediate PTF (iPTF), from 2009 to 2017 using the 1.2m Samuel Oschin telescope and the 1.52m telescope at Palomar Observatory, California, USA.
- ID:
- ivo://CDS.VizieR/J/ApJ/860/68
- Title:
- Type IIn Supernova SN 2010bt photometry
- Short Name:
- J/ApJ/860/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is well known that massive stars (M>8M_{sun}_) evolve up to the collapse of the stellar core, resulting in most cases in a supernova (SN) explosion. Their heterogeneity is related mainly to different configurations of the progenitor star at the moment of the explosion and to their immediate environments. We present photometry and spectroscopy of SN 2010bt, which was classified as a Type IIn SN from a spectrum obtained soon after discovery and was observed extensively for about 2 months. After the seasonal interruption owing to its proximity to the Sun, the SN was below the detection threshold, indicative of a rapid luminosity decline. We can identify the likely progenitor with a very luminous star (log L/L_{sun}_~7) through comparison of Hubble Space Telescope images of the host galaxy prior to explosion with those of the SN obtained after maximum light. Such a luminosity is not expected for a quiescent star, but rather for a massive star in an active phase. This progenitor candidate was later confirmed via images taken in 2015 (~5yr post-discovery), in which no bright point source was detected at the SN position. Given these results and the SN behavior, we conclude that SN 2010bt was likely a Type IIn SN and that its progenitor was a massive star that experienced an outburst shortly before the final explosion, leading to a dense H-rich circumstellar environment around the SN progenitor.
