224 research outputs found
PISCO: The Pmas/ppak Integral-field Supernova hosts COmpilation
We present the Pmas/ppak Integral-field Supernova hosts COmpilation (PISCO)
which comprises Integral Field Spectroscopy (IFS) of 232 supernova (SN) host
galaxies, that hosted 272 SNe, observed over several semesters with the 3.5m
telescope at the Calar Alto Observatory (CAHA). PISCO is the largest collection
of SN host galaxies observed with wide-field IFS, totaling 466,347 individual
spectra covering a typical spatial resolution of 380 pc. While focused
studies regarding specific SN Ia- related topics will be published elsewhere,
this paper aims to present the properties of the SN environments with stellar
population (SP) synthesis and the gas-phase ISM, providing additional results
separating stripped-envelope SNe into their subtypes. With 11,270 HII regions
detected in all galaxies, we present for the first time an HII region
statistical analysis, that puts HII regions that have hosted SNe in context
with all other SF clumps within their galaxies. SNe Ic are associated to more
metal-rich, higher EW(H{\alpha}) and higher SF rate environments within their
host galaxies than the mean of all HII regions detected within each host, on
contrary SNe IIb occur at the most different environments compared to other CC
SNe types. We find two clear components of young and old SP at SNe IIn
locations. We find that SNe II fast-decliners (IIL) tend to explode at
locations where {\Sigma}SFR is more intense. Finally, we outline how a future
dedicated IFS survey of galaxies in parallel to an untargeted SN search would
overcome the biases in current environmental studies.Comment: 21 pages, 10 Figures, 6 Tables. Accepted in Ap
Supernova 2014J at M82 – II. Direct analysis of a middle-class Type Ia supernova
We analyze a time series of optical spectra of SN 2014J from almost two weeks prior to maximum to nearly four months after maximum. We perform our analysis using the SYNOW code, which is well suited to track the distribution of the ions with velocity in the ejecta. We show that almost all of the spectral features during the entire epoch can be identified with permitted transitions of the common ions found in normal SNe Ia in agreement with previous studies. We show that 2014J is a relatively normal SN Ia. At early times the spectral features are dominated by Si II, S II, Mg II, and Ca II. These ions persist to maximum light with the appearance of Na I and Mg I. At later times iron-group elements also appear, as expected in the stratified abundance model of the formation of normal type Ia SNe. We do not find significant spectroscopic evidence for oxygen, until 100 days after maximum light. The +100 day identification of oxygen is tentative, and would imply significant mixing of unburned or only slight processed elements down to a velocity of 6,000 km~s−1. Our results are in relatively good agreement with other analyses in the IR. We briefly compare SN 2011fe to SN 2014J and conclude that the differences could be due to different central densities at ignition or differences in the C/O ratio of the progenitors
Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory
The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been
used for the past 25 years as a reference source in TeV astronomy, for
calibration and verification of new TeV instruments. The High Altitude Water
Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe
the Crab Nebula at high significance across nearly the full spectrum of
energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view,
nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's
sensitivity improves with the gamma-ray energy. Above 1 TeV the
sensitivity is driven by the best background rejection and angular resolution
ever achieved for a wide-field ground array.
We present a time-integrated analysis of the Crab using 507 live days of HAWC
data from 2014 November to 2016 June. The spectrum of the Crab is fit to a
function of the form . The data is well-fit with values of
, , and
log when
is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the
systematic errors in this HAWC measurement is discussed and estimated to be
50\% in the photon flux between 1 and 37 TeV.
Confirmation of the Crab flux serves to establish the HAWC instrument's
sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of
current-generation observatories and open a new view of 2/3 of the sky above 10
TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa
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