- 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.
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Search Results
- 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/AcA/58/293
- Title:
- Type-II and anomalous Cepheids in LMC
- Short Name:
- J/AcA/58/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the second part of the OGLE-III Catalog of Variable Stars (OIII-CVS) we present 197 type II Cepheids and 83 anomalous Cepheids in the Large Magellanic Cloud (LMC). The sample of type II Cepheids consists of 64 BL Her stars, 96 W Vir stars and 37 RV Tau stars. Anomalous Cepheids are divided into 62 fundamental-mode and 21 first-overtone pulsators. These are the largest samples of such types of variable stars detected anywhere outside the Galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A70
- Title:
- Type II and anomalous Cepheids luminosities
- Short Name:
- J/A+A/603/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Type II and anomalous Cepheids (ACs) are useful distance indicators when there are too few classical Cepheids or when RR Lyrae stars are too faint. Type II and ACs follow a period-luminosity relation as well, but they are less well-studied classes of objects. In this paper we study the sample of 335 Type II and ACs in the Small and Large Magellanic Clouds detected in OGLE-III data. The spectral energy distributions (SEDs) are constructed from photometric data available in the literature and fitted with a dust radiative transfer model, thereby leading to a determination of luminosity and effective temperature. In addition, a subsample of targets is investigated for possible binarity by looking for the light-time travel effect (LITE). Hertzsprung-Russell diagrams (HRD) are constructed and compared to evolutionary tracks and theoretical instability strips (ISs). In agreement with previous suggestions, the BL Her subclass can be explained by the evolution of ~0.5-0.6M_{sun}_ stars evolving off the zero-age horizontal branch and the ACs can be explained by the evolution of ~1.1-2.3M_{sun}_ stars. The evolution of the W Vir subclass is not clear. These objects are at higher luminosities than ACs and evolutionary tracks of ~2.5-4M_{sun}_ stars cross this region in the HRD, but the periods of the W Vir are longer than those of the short period classical Cepheids at these luminosities, which indicates the former have lower masses. A low-mass star experiencing a thermal pulse when the envelope mass is small can make a blue loop into the IS region of the W Vir stars. But the timescale is extremely short, so this is also no explanation for the W Vir as a class. A relation to binarity might be at the origin of the W Vir stars, which has already been explicitly suggested for the peculiar W Vir stars. For ~60% of the RV Tau and ~10% of the W Vir objects an infrared excess is detected from the SED fitting. A recent result is confirmed that stars exist with luminosities below that predicted from single-star evolution, which show a clear infrared excess, and the shape of the excess suggests a connection to binary evolution. The investigation of the LITE effect revealed 20 systems that appear to show periodic variations and may be new binaries, although this study requires follow-up. About 40 stars show significant period changes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/268
- Title:
- Type II bursts in the Rapid Burster
- Short Name:
- J/MNRAS/449/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Type II bursts are thought to arise from instabilities in the accretion flow on to a neutron star in an X-ray binary. Despite having been known for almost 40 years, no model can yet satisfactorily account for all their properties. To shed light on the nature of this phenomenon and provide a reference for future theoretical work, we study the entire sample of Rossi X-ray Timing Explorer data of type II bursts from the Rapid Burster (MXB 1730-335). We find that type II bursts are Eddington-limited in flux, that a larger amount of energy goes in the bursts than in the persistent emission, that type II bursts can be as short as 0.130s, and that the distribution of recurrence times drops abruptly below 15-18s. We highlight the complicated feedback between type II bursts and the NS surface thermonuclear explosions known as type I bursts, and between type II bursts and the persistent emission. We review a number of models for type II bursts. While no model can reproduce all the observed burst properties and explain the source uniqueness, models involving a gating role for the magnetic field come closest to matching the properties of our sample. The uniqueness of the source may be explained by a special combination of magnetic field strength, stellar spin period and alignment between the magnetic field and the spin axis.