2,833 research outputs found
Classifications of the Host Galaxies of Supernovae, Set II
Classifications on the DDO system are given for an additional 231 host
galaxies of supernovae that have been discovered during the course of the Lick
Observatory Supernova Search with the Katzman Automatic Imaging Telescope
(KAIT). This brings the total number of hosts of supernovae discovered (or
independently rediscovered) by KAIT, which have so far been classified on a
homogeneous system, to 408. The probability that SNe Ia and SNe II have a
different distribution of host galaxy Hubble types is found to be 99.7%. A
significant difference is also found between the distributions of the host
galaxies of SNe Ia and of SNe Ibc (defined here to include SNe Ib, Ib/c, and
Ic). However, no significant difference is detected between the frequency
distributions of the host galaxies of SNe II and SNe IIn. This suggests that
SNe IIn are generally not SNe Ia embedded in circumstellar material that are
masquerading as SNe II. Furthermore, no significant difference is found between
the distribution of the Hubble types of the hosts of SNe Ibc and of SNe II.
Additionally, SNe II-P and SNe II-L are found to occur among similar stellar
populations. The ratio of the number of SNe Ia-pec to normal SNe Ia appears to
be higher in early-type galaxies than it is in galaxies of later morphological
types. This suggests that the ancestors of SNe Ia-pec may differ systematically
in age or composition from the progenitors of normal SNe Ia. Unexpectedly, five
SNe of Types Ib/c, II, and IIn (all of which are thought to have massive
progenitors) are found in host galaxies that are nominally classified as types
E and S0. However, in each case the galaxy classification is uncertain, or
newly inspected images show evidence suggesting a later classification
(abridged) ...Comment: Accepted for publishing in PAS
Geometricity for derived categories of algebraic stacks
We prove that the dg category of perfect complexes on a smooth, proper
Deligne-Mumford stack over a field of characteristic zero is geometric in the
sense of Orlov, and in particular smooth and proper. On the level of
triangulated categories, this means that the derived category of perfect
complexes embeds as an admissible subcategory into the bounded derived category
of coherent sheaves on a smooth, projective variety. The same holds for a
smooth, projective, tame Artin stack over an arbitrary field.Comment: 31 page
Classifications of the Host Galaxies of Supernovae
Classifications on the DDO system are given for the host galaxies of 177
supernovae (SNe) that have been discovered since 1997 during the course of the
Lick Observatory Supernova Search with the Katzman Automatic Imaging Telescope.
Whereas SNe Ia occur in all galaxy types, it is found, at a high level of
statistical confidence, that SNe Ib, Ic, and II are strongly concentrated in
late-type galaxies. However, attention is drawn to a possible exception
provided by SN 2001I. This SN IIn occurred in the E2 galaxy UGC 2836, which was
not expected to harbor a massive young supernova progenitor.Comment: Accepted to be published in PAS
The Nearest Group of Galaxies
The small Antlia-Sextans clustering of galaxies is located at a distance of
only 1.36 Mpc from the Sun, and 1.72 Mpc from the adopted barycenter of the
Local Group. The latter value is significantly greater than the radius of the
zero- velocity surface of the Local Group which, for an assumed age of 14 Gyr,
has Ro = 1.18 " 0.15 Mpc. This, together with the observation that the members
of the Ant-Sex group have a mean redshift of +114 " 12 km s-1 relative to the
centroid of the Local Group, suggests that the Antlia-Sextans group is not
bound to our Local Group, and that it is expanding with the Hubble flow. If
this conclusion is correct, then Antlia-Sextans may be the nearest external
clustering of galaxies. The total galaxian population of the Ant-Sex group is ~
1/5 that of the Local Group. However, the integrated luminosity of Ant-Sex is
two orders of magnitude lower than that of the Local Group.
Subject headings: Galaxies - clusters: individual (Antlia-Sextans)Comment: Has been accepted for publication in the Astrophysical Journal
Letter
Crop ontology in support of conservation and use of banana genetic resources
Poster presented at Workshop on Crop Ontology and Phenotyping Data Interoperability. Montpellier (France), 31 Mar-4 Apr 201
On L-infinity morphisms of cyclic chains
Recently the first two authors constructed an L-infinity morphism using the
S^1-equivariant version of the Poisson Sigma Model (PSM). Its role in
deformation quantization was not entirely clear. We give here a "good"
interpretation and show that the resulting formality statement is equivalent to
formality on cyclic chains as conjectured by Tsygan and proved recently by
several authors.Comment: 11 page
Optical Observations of PSR J0205+6449
PSR J0205+6449 is a X-ray and radio pulsar in supernova remnant 3C 58. We
report on observations of the central region of 3C 58 using the 4.2-m William
Herschel Telescope with the intention of identifying the optical counterpart of
PSR J0205+6449 and characterising its pulsar wind nebula.
Around the pulsar position we identified extended emission with a magnitude
of B = 23 \fm 97 \pm 0.10, V = 22 \fm 95 \pm 0.05 and R = 22 \fm 15 \pm
0.03 consistent with a pulsar wind nebula. From the R-band image we identified
three knots with = 24 \fm 08 \pm 0.07 (o1), 24 \fm 15 \pm 0.07 (o2)
and 24 \fm 24 \pm 0.08 (o3). We confirm the presence of an optical pulsar
wind nebula around PSR J0205+6449 and give an upper limit of 24
for the optical magnitude of the pulsar. Furthermore we make the tentative
suggestion that our object o1, with an 24.08 is the optical
counterpart. If confirmed the pulsar would have an and
an optical efficiency of about 5% of the Crab pulsar. Such a low efficiency is
more consistent with the characteristic age of the pulsar rather than that of
SN 1181.Comment: The paper contains 3 figures and 3 tables, accepted for publication
in MNRA
Some Systematics of Galactic Globular Clusters
The global properties of all known Galactic globular clusters are examined.
The relationship between the luminosities and the metallicities of Galactic
globular clusters is found to be complex. Among luminous clusters there is a
correlation in the sense that the oldest clusters are slightly more metal
deficient than are younger clusters. However, no such clear-cut relationship is
found among the faintest globular clusters. The central concentration index C
of globular clusters is seen to be independent of metallicity. The dependence
of the half-light radii of globular clusters on their Galactocentric distances
can be approximated by the relation . Clusters with
collapsed cores are mostly situated close to the Galactic nucleus. For kpc the luminosities and the radii of clusters appear to be uncorrelated.
The Galaxy differs from the LMC and the SMC in that it appears to lack highly
flattened luminous clusters. Galactic globular clusters with ages 13.0
Gyr are all of Oosterhoff type II, whereas almost all of those with ages
13.0 Gyr have been assigned to Oosterhoff type I. Globular clusters with ages
11.5 Gyr are all located in the outer Galactic halo, have below-average
luminosities and above-average radii. On the other hand the very old globular
cluster NGC 6522 is situated close to the Galactic nucleus.Comment: PASP, in pres
Classifications of the Host Galaxies of Supernovae, Set III
A homogeneous sample comprising host galaxies of 604 recent supernovae,
including 212 objects discovered primarily in 2003 and 2004, has been
classified on the David Dunlap Observatory system. Most SN 1991bg-like SNe Ia
occur in E and E/Sa galaxies, whereas the majority of SN 1991T-like SNe Ia
occur in intermediate-type galaxies. This difference is significant at the
99.9% level. As expected, all types of SNe II are rare in early-type galaxies,
whereas normal SNe Ia occur in all Hubble types. This difference is significant
at the 99.99% level. A small number of SNe II in E galaxies might be due to
galaxy classification errors, or to a small young-population component in these
mainly old objects. No significant difference is found between the
distributions over Hubble type of SNe Ibc and SNe II. This confirms that both
of these types of objects have similar (massive) progenitors. The present data
show that, in order to understand the dependence of supernova type on
host-galaxy population, it is more important to obtain accurate morphological
classifications than it is to increase the size of the data sample.Comment: Accepted for publishing in PAS
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
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