The time delay between the formation of the progenitor systems of Type Ia supernovae (SNe Ia) and their detonation is a vital discriminant between the various progenitor scenarios that have been proposed for them. We use SDSS optical and GALEX ultraviolet observations of the early-type host galaxies of 21 nearby SNe Ia and quantify the presence or absence of any young stellar population to constrain the minimum time delay for each supernova. We find that early-type host galaxies lack `prompt' SNe Ia with time delays of <100 Myr and that ~70% SNe Ia have minimum time delays of 275 Myr -- 1.25 Gyr, with a median of 650 Myr, while at least 20% SNe Ia have minimum time delays of at least 1 Gyr at 95% confidence and two of these four SNe Ia are are likely older than 2 Gyr. The distribution of minimum time delays observed matches most closely the expectation for the single-degenerate channel with a main sequence donor. Furthermore, we do not find any evidence that sub-luminous SNe Ia are associated with long time delays.
We present the early UV and optical light curve of Type IIP supernova (SN) 2010aq at z=0.0862, and compare it to analytical models for thermal emission following SN shock breakout in a red supergiant star. SN 2010aq was discovered in joint monitoring between the Galaxy Evolution Explorer (GALEX) Time Domain Survey (TDS) in the NUV and the Pan-STARRS1 Medium Deep Survey (PS1 MDS) in the g, r, i, and z bands. The GALEX and Pan-STARRS1 observations detect the SN less than 1 day after shock breakout, measure a diluted blackbody temperature of 31,000 +/- 6,000 K 1 day later, and follow the rise in …
Old Universe, Young SNe Ia: A Statistical Analysis of Type Ia Supernova Progenitor Age from 6,983 TITAN Host Galaxies, and Implications for Cosmology
Johns Hopkins University（约翰斯·霍普金斯大学）；University of Oxford（牛津大学）；University of Southampton（南安普顿大学）；Rutgers, the State University of New Jersey（新泽西州立罗格斯大学）；Space Telescope Science Institute（太空望远镜科学研究所）；Boston University（波士顿大学）；University of Hawai’i（夏威夷大学）
We present observational constraints on the nature of core-collapse supernovae through an investigation into their radial distributions with respect to those of young and old stellar populations within their host galaxies, as traced by H-alpha emission and R-band light respectively. We discuss results and the implications they have on the nature of supernova progenitors, for a sample of 177 core-collapse supernovae. We find that the radial positions of the overall core-collapse population closely follow the radial distribution of H-alpha emission, implying that both are excellent tracers of st…
In the local Universe, 10% of massive elliptical galaxies are observed to exhibit a peculiar property: a substantial excess of ultraviolet emission (UVX) over what is expected from their old, red stellar populations. Several origins for the UVX have been proposed, including a population of hot young stars, or a population of old, blue horizontal branch or extended horizontal branch (BHB or EHB) stars that have undergone substantial mass loss from their outer atmospheres. We explore the radial distribution of ultraviolet excess (UVX) in a selection of 49 nearby E/S0-type galaxies by measuring t…
The luminosities of Type Ia supernovae (SNe), the thermonuclear explosions of white-dwarf stars, vary systematically with their intrinsic color and the rate at which they fade. From images taken with the Galaxy Evolution Explorer (GALEX), we identified SNe Ia that erupted in environments that have high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, we calibrate these SNe using their broadband optical light curves to within ~0.065 to 0.075 magnitudes, corresponding to <4% in distance. The tight scatter, probably arising from a smal…
We present constraints on supernovae type Ia (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 GALEX near-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 types. It is also found that they do not trace near-UV emission. As the latter traces SF on timescales less than 100 Myr, this rules out any extreme '…
The radius and surface composition of an exploding massive star,as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN ra…
Strong Balmer absorption lines and the lack of Ha and [OII] emission lines signify that E+As are post-starburst systems. Recent studies suggest that E+As may undergo the transition from the `blue cloud' to the `red sequence' and eventually migrate to red sequence ETGs. An observational validation of this scenario is to identify the intervening galaxy population between E+As and the red-sequence. Motivated by recent findings with GALEX that a large fraction of ETGs exhibit UV-excess as a sign of RSF, we investigate the possible connection of the UV-excess galaxies to E+As. In particular, we exa…
The nearby universe remains the best laboratory to understand physical properties of galaxies and is a reference for any comparison with high redshift observations. The all sky (or very large) surveys performed from the ultraviolet (UV) to the far-infrared (far-IR) gives us large datasets with a very large wavelength coverage to perform a reference study. We want to investigate dust attenuation characteristics as well as star formation rate (SFR) calibrations on a sample of nearby galaxies observed over 13 bands from 0.15 to 160 microns. A sample of 363 galaxies is built from the AKARI /FIS al…
We present GALEX far-ultraviolet (FUV, $λ_{eff}$=1538 Å) and near-ultraviolet (NUV, $λ_{eff}$=2316 Å) surface photometry of 40 early-type galaxies (ETGs) selected from a wider sample of 65 nearby ETGs showing emission lines in their optical spectra. We derive FUV and NUV surface brightness profiles, (FUV-NUV) colour profiles and D$_{25}$ integrated magnitudes. We extend the photometric study to the optical {\it r} band from SDSS imaging for 14 of these ETGs. In general, the (FUV-NUV) radial colour profiles become redder with galactocentric distance in both rejuvenated ($\leq 4$ Gyr) and old ET…
B514 is a remote M31 globular cluster which locating at a projected distance of R_p~55 kpc. Deep observations with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) are used to provide the accurate integrated light and star counts of B514. By coupling analysis of the distribution of the integrated light with star counts, we are able to reliably follow the profile of the cluster out to ~40". Based on the combined profile, we study in detail its surface brightness distribution in F606W and F814W filters, and determine its structural parameters by fitting a single-mass iso…
This paper supplements Jiang et al. (2003), who studied 172 M31 globular clusters (GCs) and globular cluster candidates from Battistini et al. (1987) on the basis of integrated photometric measurements in the Beijing-Arizona-Taiwan-Connecticut (BATC) photometric system. Here, we present multicolor photometric CCD data (in the BATC system) for the remaining 39 M31 GCs and candidates. In addition, the ages of 35 GCs are constrained by comparing our accurate photometry with updated theoretical stellar synthesis models. We use photometric measurements from GALEX in the far- and near-ultraviolet an…
We present a comprehensive study on the impact of the environment of compact galaxy groups on the evolution of their members using a multi-wavelength analysis, from the UV to the infrared, for a sample of 32 Hickson compact groups (HCGs) containing 135 galaxies. Fitting the SEDs of all galaxies with the state-of-the-art model of da Cunha (2008) we can accurately calculate their mass, SFR, and extinction, as well as estimate their infrared luminosity and dust content. We compare our findings with samples of field galaxies, early-stage interacting pairs, and cluster galaxies with similar data. W…
The AKARI All-Sky Survey provided the first bright point source catalog detected at 90um. Starting from this catalog, we selected galaxies by matching AKARI sources with those in the IRAS PSCz. Next, we have measured total GALEX FUV and NUV flux densities. Then, we have matched this sample with SDSS and 2MASS galaxies. By this procedure, we obtained the final sample which consists of 607 galaxies. If we sort the sample with respect to 90um, their average SED shows a coherent trend: the more luminous at 90um, the redder the global SED becomes. The M_r--NUV-r color-magnitude relation of our samp…
Supernova (SN) cosmology is based on the assumption that the width-luminosity relation (WLR) and the color-luminosity relation (CLR) in the type Ia SN luminosity standardization would not show {absolute magnitude differences} with progenitor age. Unlike this expectation, recent age datings of stellar populations in host galaxies have shown significant correlations between progenitor age and Hubble residual (HR). Here we show that this correlation originates from a strong progenitor age dependence of the zero-points of the WLR and the CLR, in the sense that SNe from younger progenitors are fain…
Using H-alpha emission as a tracer of on-going (<16 Myr old) and near-UV emission as a tracer of recent (16-100 Myr old) star formation (SF), we present constraints on core-collapse (CC) supernova (SN) progenitors through their association with SF regions. We present statistics of a large sample of SNe; 163.5 type II (58 IIP, 13 IIL, 13.5 IIb, 19 IIn and 12 'impostors') and 96.5 type Ib/c (39.5 Ib and 52 Ic). Using pixel statistics our main findings and conclusions are: 1) An increasing progenitor mass sequence is observed, implied from an increasing association of SNe to host galaxy H-alpha e…
We undertake a statistical analysis of the radial abundance distributions in the Galactic disk within a theoretical framework for Galactic chemical evolution which incorporates the influence of spiral arms. 1) The mean mass of oxygen ejected per core-collapse SNe (CC SNe) event (which are concentrated within spiral arms) is $\sim$0.27 M$_{\odot}$; 2) the mean mass of iron ejected by `tardy' Type Ia SNe (SNeIa; progenitors of whom are older/longer-lived stars with ages $\simgt$100 Myr and up to several Gyr, which do not concentrate within spiral arms) is $\sim$0.58 M$_{\odot}$; 3) the upper mas…
Comparing N-body calculations that include primordial residual-gas expulsion with the observed properties of 20 Galactic globular clusters (GCs) for which the stellar mass function (MF) has been measured, we constrain the time-scale over which the gas of their embedded counterparts must have been removed, the star formation efficiency the progenitor cloud must have had and the strength of the tidal-field the clusters must have formed in. The three parameters determine the expansion and mass-loss during residual-gas expulsion. After applying corrections for stellar and dynamical evolution we fi…
Using the UltraVISTA catalogs, we investigate the evolution in the 11.4~Gyr since $z=3$ of the progenitors of local ultra-massive galaxies ($\log{(M_{\rm star}/M_{\odot})}\approx11.8$; UMGs), providing a complete and consistent picture of how the most massive galaxies at $z=0$ have assembled. By selecting the progenitors with a semi-empirical approach using abundance matching, we infer a growth in stellar mass of 0.56$^{+0.35}_{-0.25}$ dex, 0.45$^{+0.16}_{-0.20}$~dex, and 0.27$^{+0.08}_{-0.12}$ dex from $z=3$, $z=2$, and $z=1$, respectively, to $z=0$. At $z<1$, the progenitors of UMGs constitu…
To address the question of whether the so-called ultra compact dwarf galaxies (UCDs) are the remnant nuclei of destroyed early-type dwarf galaxies (dEs), we analyze the stellar population parameters of the nuclei of 34 Virgo dEs, as well as ten Virgo UCDs, including one that we discovered and which we report on here. Based on absorption line strength (Lick index) measurements, we find that nuclei of Virgo dEs have younger stellar population ages than UCDs, with averages of 5 Gyr and >10 Gyr, respectively. In addition to this, the metallicity also differs: dE nuclei are on average more metal-ri…
We present a comprehensive theoretical study, using a semi-analytical model within the standard LCDM framework, of the photometric properties of the progenitors of present-day early-type galaxies in the redshift range 0<z<1. We explore progenitors of all morphologies and study their characteristics as a function of the luminosity and local environment of the early-type remnant at z=0. In agreement with previous studies, we find that, while larger early-types are generally assembled later, their luminosity-weighted stellar ages are typically older. In dense cluster-like environments, 70% of ear…
We present a study of the properties of the host galaxies of unusual transient objects of two types, both being sub-luminous compared with the major classes of supernovae. Those of one type exhibit unusually strong calcium features, and have been termed 'Ca-rich'. Those of the second type, with SN2002cx as the prototype and SN2008ha as the most extreme example to date, have some properties in common with the first, but show typically lower ejecta velocities, and different early spectra. We confirm important differences in the environments of the two types, with the Ca-rich transients preferent…
Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra ($\leq 10$ days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 Type II SNe showing flash-ionized (FI) signatures in th…
