3,724 research outputs found
The Host Galaxies of Fast-Ejecta Core-Collapse Supernovae
Spectra of broad-lined Type Ic supernovae (SN Ic-BL), the only kind of SN
observed at the locations of long-duration gamma-ray bursts (LGRBs), exhibit
wide features indicative of high ejecta velocities (~0.1c). We study the host
galaxies of a sample of 245 low-redshift (z<0.2) core-collapse SN, including 17
SN Ic-BL, discovered by galaxy-untargeted searches, and 15 optically luminous
and dust-obscured z<1.2 LGRBs. We show that, in comparison with SDSS galaxies
having similar stellar masses, the hosts of low-redshift SN Ic-BL and z<1.2
LGRBs have high stellar-mass and star-formation-rate densities. Core-collapse
SN having typical ejecta velocities, in contrast, show no preference for such
galaxies. Moreover, we find that the hosts of SN Ic-BL, unlike those of SN
Ib/Ic and SN II, exhibit high gas velocity dispersions for their stellar
masses. The patterns likely reflect variations among star-forming environments,
and suggest that LGRBs can be used as probes of conditions in high-redshift
galaxies. They may be caused by efficient formation of massive binary
progenitors systems in densely star-forming regions, or, less probably, a
higher fraction of stars created with the initial masses required for a SN
Ic-BL or LGRB. Finally, we show that the preference of SN Ic-BL and LGRBs for
galaxies with high stellar-mass and star-formation-rate densities cannot be
attributed to a preference for low metal abundances but must reflect the
influence of a separate environmental factor.Comment: Accepted by ApJ 9 May 2014 with only minor revision
Multiple Images of a Highly Magnified Supernova Formed by an Early-Type Cluster Galaxy Lens
In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the MACS J1149.6+2223 cluster. The cluster’s gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. The magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses
Long Gamma-Ray Bursts and Type Ic Core Collapse Supernovae Have Similar Locations in Hosts
When the afterglow fades at the site of a long-duration gamma-ray burst
(LGRB), Type Ic supernovae (SN Ic) are the only type of core collapse supernova
observed. Recent work found that a sample of LGRB in high-redshift galaxies had
different environments from a collection of core-collapse environments, which
were identified from their colors and light curves. LGRB were in the brightest
regions of their hosts, but the core-collapse sample followed the overall
distribution of the galaxy light. Here we examine 504 supernovae with types
assigned based on their spectra that are located in nearby (z < 0.06) galaxies
for which we have constructed surface photometry from the Sloan Digital Sky
Survey (SDSS). The distributions of the thermonuclear supernovae (SN Ia) and
some varieties of core-collapse supernovae (SN II and SN Ib) follow the galaxy
light, but the SN Ic (like LGRB) are much more likely to erupt in the brightest
regions of their hosts. The high-redshift hosts of LGRB are overwhelmingly
irregulars, without bulges, while many low redshift SN Ic hosts are spirals
with small bulges. When we remove the bulge light from our low-redshift sample,
the SN Ic and LGRB distributions agree extremely well. If both LGRB and SN Ic
stem from very massive stars, then it seems plausible that the conditions
necessary for forming SN Ic are also required for LGRB. Additional factors,
including metallicity, may determine whether the stellar evolution of a massive
star leads to a LGRB with an underlying broad-lined SN Ic, or simply a SN Ic
without a gamma-ray burst.Comment: Accepted by the Astrophysical Journal, 12 pages, 3 tables, 4 figures,
SN sample size increases from 263 to 504 in v2, varying host magnitude and
distance shown not to introduce systematic error in measurement
Constraints on the Progenitor System of the Type Ia Supernova 2014J from Pre-Explosion Hubble Space Telescope Imaging
We constrain the properties of the progenitor system of the highly reddened
Type Ia supernova (SN) 2014J in Messier 82 (M82; d ~ 3.5 Mpc). We determine the
SN location using Keck-II K-band adaptive optics images, and we find no
evidence for flux from a progenitor system in pre-explosion near-ultraviolet
through near-infrared Hubble Space Telescope (HST) images. Our upper limits
exclude systems having a bright red giant companion, including symbiotic novae
with luminosities comparable to that of RS Ophiuchi. While the flux constraints
are also inconsistent with predictions for comparatively cool He-donor systems
(T < ~35,000 K), we cannot preclude a system similar to V445 Puppis. The
progenitor constraints are robust across a wide range of R_V and A_V values,
but significantly greater values than those inferred from the SN light curve
and spectrum would yield proportionally brighter luminosity limits. The
comparatively faint flux expected from a binary progenitor system consisting of
white dwarf stars would not have been detected in the pre-explosion HST
imaging. Infrared HST exposures yield more stringent constraints on the
luminosities of very cool (T < 3000 K) companion stars than was possible in the
case of SN Ia 2011fe.Comment: Accepted by ApJ 14 May 2014 with only minor revision
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