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James D. Neill,
Mark Sullivan,
Avishay Gal-Yam,
Robert Quimby,
Eran Ofek,
Ted K. Wyder,
D. Andrew Howell,
Peter Nugent,
Mark Seibert,
D. Christopher Martin, [......],
Susan G. Neff,
David Schiminovich,
Luciana Bianchi,
José Donas,
Timothy M. Heckman,
Young-Wook Lee,
Barry F. Madore,
Bruno Milliard,
R. Michael Rich,
Alex S. Szalay
[show abstract]
[hide abstract]
ABSTRACT: We use GALEX ultraviolet (UV) and optical integrated photometry of the hosts of seventeen luminous supernovae (LSNe, having peak M_V < -21) and compare them to a sample of 26,000 galaxies from a cross-match between the SDSS DR4 spectral catalog and GALEX interim release 1.1. We place the LSNe hosts on the galaxy NUV-r versus M_r color magnitude diagram (CMD) with the larger sample to illustrate how extreme they are. The LSN hosts appear to favor low-density regions of the galaxy CMD falling on the blue edge of the blue cloud toward the low luminosity end. From the UV-optical photometry, we estimate the star formation history of the LSN hosts. The hosts have moderately low star formation rates (SFRs) and low stellar masses (M_*) resulting in high specific star formation rates (sSFR). Compared with the larger sample, the LSN hosts occupy low-density regions of a diagram plotting sSFR versus M_* in the area having higher sSFR and lower M_*. This preference for low M_*, high sSFR hosts implies the LSNe are produced by an effect having to do with their local environment. The correlation of mass with metallicity suggests that perhaps wind-driven mass loss is the factor that prevents LSNe from arising in higher-mass, higher-metallicity hosts. The massive progenitors of the LSNe (>100 M_sun), by appearing in low-SFR hosts, are potential tests for theories of the initial mass function that limit the maximum mass of a star based on the SFR. Comment: 8 pages, 3 figures, 2 tables, accepted to ApJ, amended references and updated SN designations
11/2010;
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James D. Neill,
Mark Sullivan,
D. Andrew Howell,
Alex Conley,
Mark Seibert,
D. Christopher Martin,
Tom A. Barlow, Karl Foster,
Peter G. Friedman,
Patrick Morrissey, [......],
David Schiminovich,
Ted K. Wyder,
Luciana Bianchi,
José Donas,
Timothy M. Heckman,
Young-Wook Lee,
Barry F. Madore,
Bruno Milliard,
R. Michael Rich,
and Alex S. Szalay
[show abstract]
[hide abstract]
ABSTRACT: We use multi-wavelength, matched aperture, integrated photometry from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the RC3 to estimate the physical properties of 166 nearby galaxies hosting 168 well-observed Type Ia supernovae (SNe Ia). The ultraviolet (UV) imaging of local SN Ia hosts from GALEX allows a direct comparison with higher-redshift hosts measured at optical wavelengths that correspond to the rest-frame UV. Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast, and fewer bright, slow SNe Ia than younger hosts. New results include that in our sample, the faintest and fastest SNe Ia occur only in galaxies exceeding a stellar mass threshold of ~1010 M ☉, leading us to conclude that their progenitors must arise in populations that are older and/or more metal rich than the general SN Ia population. A low host extinction subsample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average. This has implications for cosmological fitting of SNe Ia, and suggests that host age could be useful as a parameter in the fitting. Converting host mass to metallicity and computing 56Ni mass from the supernova light curves, we find that our local sample is consistent with a model that predicts a shallow trend between stellar metallicity and the 56Ni mass that powers the explosion, but we cannot rule out the absence of a trend. We measure a correlation between 56Ni mass and host age in the local universe that is shallower and not as significant as that seen at higher redshifts. The details of the age-56Ni mass correlations at low and higher redshift imply a luminosity-weighted age threshold of ~3 Gyr for SN Ia hosts, above which they are less likely to produce SNe Ia with 56Ni masses above ~0.5 M ☉.
The Astrophysical Journal 12/2009; 707(2):1449. · 6.02 Impact Factor
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Yun-Kyeong Sheen,
Hyunjin Jeong,
Sukyoung K. Yi,
Ignacio Ferreras,
Jennifer M. Lotz,
Knut A. G. Olsen,
Mark Dickinson,
Sydney Barnes,
Jang-Hyun Park,
Chang H. Ree, [......], Karl Foster,
Peter G. Friendman,
Young-Wook Lee,
D. Christopher Martin,
Patrick Morrissey,
Susan G. Neff,
David Schiminovich,
Mark Seibert,
Todd Small,
and Ted K. Wyder
[show abstract]
[hide abstract]
ABSTRACT: One possible channel for the formation of dwarf galaxies involves birth in the tidal tails of interacting galaxies. We report the detection of a bright UV tidal tail and several young tidal dwarf galaxy (TDG) candidates in the post-merger galaxy NGC 4922 in the Coma cluster. Based on a two-component population model (combining young and old stellar populations), we find that the light of tidal tail predominantly comes from young stars (a few Myr old). The Galaxy Evolution Explorer ultraviolet data played a critical role in the parameter (age and mass) estimation. Our stellar mass estimates of the TDG candidates are ~106–7 M ☉, typical for dwarf galaxies.
The Astronomical Journal 11/2009; 138(6):1911. · 4.03 Impact Factor
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Soo-Chang Rey,
Sangmo T. Sohn,
Michael A. Beasley,
Young-Wook Lee,
R. Michael Rich,
Suk-Jin Yoon,
Sukyoung K. Yi,
Luciana Bianch,
Yongbeom Kang,
Kyeongsook Lee, [......],
Susan G. Neff,
David Schiminovich,
Mark Seibert,
Ted K. Wyder,
Jose Donas,
Timothy M. Heckman,
Barry F. Madore,
Bruno Milliard,
Alex S. Szalay,
Barry Y. Welsh
[show abstract]
[hide abstract]
ABSTRACT: We explore the age distribution of the globular cluster (GC) system of the nearby elliptical galaxy NGC 5128 using ultraviolet (UV) photometry from Galaxy Evolution Explorer (GALEX) observations, with UV - optical colors used as the age indicator. Most GCs in NGC 5128 follow the general trends of GCs in M31 and Milky Way in UV - optical color-color diagram, which indicates that the majority of GCs in NGC 5128 are old similar to the age range of old GCs in M31 and Milky Way. A large fraction of spectroscopically identified intermediate-age GC (IAGC) candidates with ~ 3-8 Gyr are not detected in the FUV passband. Considering the nature of intermediate-age populations being faint in the far-UV (FUV) passband, we suggest that many of the spectroscopically identified IAGCs may be truly intermediate in age. This is in contrast to the case of M31 where a large fraction of spectroscopically suggested IAGCs are detected in FUV and therefore may not be genuine IAGCs but rather older GCs with developed blue horizontal branch stars. Our UV photometry strengthens the results previously suggesting the presence of GC and stellar subpopulation with intermediate age in NGC 5128. The existence of IAGCs strongly indicates the occurrence of at least one more major star formation episode after a starburst at high redshift. Comment: 8 pages, 3 figures, accepted for ApJ Letter
06/2009;
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Sébastien Heinis,
Tamás Budavári,
Alex S. Szalay,
Stéphane Arnouts,
Miguel A. Aragón-Calvo,
Ted K. Wyder,
Tom A. Barlow, Karl Foster,
Friedman G. Peter,
D. Christopher Martin, [......],
David Schiminovich,
Mark Seibert,
Luciana Bianchi,
José Donas,
Timothy M. Heckman,
Young-Wook Lee,
Barry F. Madore,
Bruno Milliard,
R. Michael Rich,
and Sukyoung K. Yi
[show abstract]
[hide abstract]
ABSTRACT: We measure the projected spatial correlation function wp (rp ) from a large sample combining Galaxy Evolution Explorer ultraviolet imaging with the Sloan Digital Sky Survey spectroscopic sample. We study the dependence of the clustering strength for samples selected on (NUV – r)abs color, specific star formation rate (SSFR), and stellar mass. We find that there is a smooth transition in the clustering of galaxies as a function of this color from weak clustering among blue galaxies to stronger clustering for red galaxies. The clustering of galaxies within the "green valley" has an intermediate strength, and is consistent with that expected from galaxy groups. The results are robust to the correction for dust extinction. The comparison with simple analytical modeling suggests that the halo occupation number increases with older star formation epochs. When splitting according to SSFR, we find that the SSFR is a more sensitive tracer of environment than stellar mass.
The Astrophysical Journal 06/2009; 698(2):1838. · 6.02 Impact Factor
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Ted K. Wyder,
D. Christopher Martin,
Tom A. Barlow, Karl Foster,
Peter G. Friedman,
Patrick Morrissey,
Susan G. Neff,
James D. Neill,
David Schiminovich,
Mark Seibert,
Luciana Bianchi,
José Donas,
Timothy M. Heckman,
Young-Wook Lee,
Barry F. Madore,
Bruno Milliard,
R. Michael Rich,
Alex S. Szalay,
and Sukyoung K. Yi
[show abstract]
[hide abstract]
ABSTRACT: We investigate the nature of the star formation law at low gas surface densities using a sample of 19 low surface brightness (LSB) galaxies with existing H I maps in the literature, UV imaging from the Galaxy Evolution Explorer satellite, and optical images from the Sloan Digital Sky Survey. All of the LSB galaxies have (NUV – r) colors similar to those for higher surface brightness star-forming galaxies of similar luminosity indicating that their average star formation histories are not very different. Based upon four LSB galaxies with both UV and far-infrared (FIR) data, we find FIR/UV ratios significantly less than 1, implying low amounts of internal UV extinction in LSB galaxies. We use the UV images and H I maps to measure the star formation rate (SFR) and hydrogen gas surface density within the same region for all the galaxies. The LSB galaxy star formation rate surface densities lie below the extrapolation of the power law fit to the SFR surface density as a function of the total gas density for higher surface brightness galaxies. Although there is more scatter, the LSB galaxies also lie below a second version of the star formation law in which the SFR surface density is correlated with the gas density divided by the orbital time in the disk. The downturn seen in both star formation laws is consistent with theoretical models that predict lower star formation efficiencies in LSB galaxies due to the declining molecular fraction with decreasing density.
The Astrophysical Journal 04/2009; 696(2):1834. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We use GALEX ultraviolet (UV) and optical integrated photometry of the hosts of 17 luminous supernovae (LSNe, having peak M_V < –21) and compare them to a sample of 26, 000 galaxies from a cross-match between the SDSS DR4 spectral catalog and GALEX interim release 1.1. We place the LSN hosts on the galaxy NUV – r versus M_r color-magnitude diagram (CMD) with the larger sample to illustrate how extreme they are. The LSN hosts appear to favor low-density regions of the galaxy CMD falling on the blue edge of the blue cloud toward the low-luminosity end. From the UV-optical photometry, we estimate the star formation history of the LSN hosts. The hosts have moderately low star formation rates (SFRs) and low stellar masses (M_*) resulting in high specific star formation rates (sSFR). Compared with the larger sample, the LSN hosts occupy low-density regions of a diagram plotting sSFR versus M_* in the area having higher sSFR and lower M_*. This preference for low M_*, high sSFR hosts implies that the LSNe are produced by an effect having to do with their local environment. The correlation of mass with metallicity suggests that perhaps wind-driven mass loss is the factor that prevents LSNe from arising in higher-mass, higher-metallicity hosts. The massive progenitors of the LSNe (>100 M_☉), by appearing in low-SFR hosts, are potential tests for theories of the initial mass function that limit the maximum mass of a star based on the SFR.
