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Start Over Subject gamma-ray astronomy
321. SED of the Fermi blazars
ID:
ivo://CDS.VizieR/J/ApJ/709/1407
Title:
SED of the Fermi blazars
Short Name:
J/ApJ/709/1407
Date:
21 Oct 2021
Publisher:
CDS
Description:
We complied the optical, X-ray, and {gamma}-ray data for 54 Fermi blazars and studied the relationship between the broadband spectral index {alpha}_ox_ and {alpha}_x{gamma}_, as well as the relationship between the intrinsic composite spectral indices {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ for this sample. The relationship between {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ reveals that flat spectrum radio quasars and low-energy peaked BL Lacertae follow a continuous trend, which is consistent with previous results, whereas high-energy peaked BL Lacertae follow a separate distinct trend. Even so, a unified scheme is also revealed from {alpha}_xox_-{alpha}_{gamma}x{gamma}_ diagram when all three subclasses of blazars are considered.
322. Shapes of GRB light curves
ID:
ivo://CDS.VizieR/J/ApJ/744/141
Title:
Shapes of GRB light curves
Short Name:
J/ApJ/744/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
The light curves of gamma-ray bursts (GRBs) are believed to result from internal shocks reflecting the activity of the GRB central engine. Their temporal deconvolution can reveal potential differences in the properties of the central engines in the two populations of GRBs which are believed to originate from the deaths of massive stars (long) and from mergers of compact objects (short). We present here the results of the temporal analysis of 42 GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope. We deconvolved the profiles into pulses, which we fit with lognormal functions. The distributions of the pulse shape parameters and intervals between neighboring pulses are distinct for both burst types and also fit with lognormal functions. We have studied the evolution of these parameters in different energy bands and found that they differ between long and short bursts. We discuss the implications of the differences in the temporal properties of long and short bursts within the framework of the internal shock model for GRB prompt emission.
323. Short gamma-ray bursts (sGRBs) data
ID:
ivo://CDS.VizieR/J/ApJ/852/1
Title:
Short gamma-ray bursts (sGRBs) data
Short Name:
J/ApJ/852/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we study the luminosity function and formation rate of short gamma-ray bursts (sGRBs). First, we derive the Ep-Lp correlation using 16 sGRBs with redshift measurements and determine the pseudo redshifts of 284 Fermi sGRBs. Then, we use the Lynden-Bell c^-^ method to study the luminosity function and formation rate of sGRBs without any assumptions. A strong evolution of luminosity L(z){propto}(1+z)^4.47^ is found. After removing this evolution, the luminosity function is {Psi}(L){propto}L_0_^-0.29+/-0.01^ for dim sGRBs and {psi}(L){propto}L_0_^-1.07+/-0.01^ for bright sGRBs, with the break point 8.26x10^50^erg/s. We also find that the formation rate decreases rapidly at z<1.0, which is different from previous works. The local formation rate of sGRBs is 7.53 events Gpc^-3^/yr. Considering the beaming effect, the local formation rate of sGRBs including off-axis sGRBs is 203.31_-135.54_^+1152.09^ events Gpc^-3^/yr. We also estimate that the event rate of sGRBs detected by the advanced LIGO and Virgo is 0.85_-0.56_^+4.82^ events yr^-1^ for an NS-NS binary.
324. Short GRBs with Fermi GBM and Swift BAT
ID:
ivo://CDS.VizieR/J/ApJ/818/110
Title:
Short GRBs with Fermi GBM and Swift BAT
Short Name:
J/ApJ/818/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM.
325. SN and LGRB locations in their host galaxies
ID:
ivo://CDS.VizieR/J/ApJ/687/1201
Title:
SN and LGRB locations in their host galaxies
Short Name:
J/ApJ/687/1201
Date:
21 Oct 2021
Publisher:
CDS
Description:
When the afterglow fades at the site of a long-duration {gamma}-ray burst (LGRB), Type Ic supernovae (SNe Ic) are the only type of core-collapse supernova observed. 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 (SNe Ia) and some varieties of core-collapse supernovae (SNe II and SNe Ib) follow the galaxy light, but the SNe Ic (like LGRBs) are much more likely to erupt in the brightest regions of their hosts.
326. SN 1998bw MUSE datacube
ID:
ivo://CDS.VizieR/J/A+A/602/A85
Title:
SN 1998bw MUSE datacube
Short Name:
J/A+A/602/A85
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spatially resolved spectroscopy of the environments of explosive transients carries detailed information about the physical properties of the stellar population that gave rise to the explosion, and thus the progenitor itself. Here, we present new observations of ESO184-G82, the galaxy hosting the archetype of the {gamma}-ray burst/supernova connection, GRB 980425/SN 1998bw, obtained with the integral field spectrograph MUSE mounted at the Very Large Telescope. These observations have yielded detailed maps of emission-line strength for various nebular lines along with physical parameters such as dust extinction, stellar age, and oxygen abundance on spatial scales of 160pc. The immediate environment of GRB 980425 is young 5-8Myr) and consistent with a mildly extinguished (AV~0.1mag) progenitor of zero-age main-sequence mass between 25 M_{sun}_ and 40 M_{sun}_ and an oxygen abundance 12+log(O=H)~8.2 (Z~0.3Z_{sun}_), which is slightly lower than that of an integrated measurement of the whole galaxy (12+log(O=H)~8.3) and a prominent nearby HII region (12+log(O/H)~8.4). This region is significantly younger than the explosion site, and we argue that a scenario in which the GRB progenitor formed in this environment and was subsequently ejected appears very unlikely. We show that empirical strong-line methods based on [O iii] and/or [N ii] are inadequate to produce accurate maps of oxygen abundance at the level of detail of our MUSE observation as these methods strongly depend on the ionization state of the gas. The metallicity gradient in ESO184-G82 is -0.06dex/kpc, indicating that the typical offsets of at most few kpc for cosmological GRBs on average have a small impact on oxygen abundance measurements at higher redshift.
327. SN IIn catalog with Fermi LAT
ID:
ivo://CDS.VizieR/J/ApJ/807/169
Title:
SN IIn catalog with Fermi LAT
Short Name:
J/ApJ/807/169
Date:
21 Oct 2021
Publisher:
CDS
Description:
Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are hypothesized to accelerate cosmic rays in collisionless shocks and emit GeV {gamma}-rays and TeV neutrinos on a timescale of several months. We perform the first systematic search for {gamma}-ray emission in Fermi Large Area Telescope data in the energy range from 100MeV to 300GeV from the ensemble of 147 SNe Type IIn exploding in a dense CSM. We search for a {gamma}-ray excess at each SNe location in a one-year time window. In order to enhance a possible weak signal, we simultaneously study the closest and optically brightest sources of our sample in a joint-likelihood analysis in three different time windows (1 year, 6 months, and 3 months). For the most promising source of the sample, SN 2010jl (PTF 10aaxf), we repeat the analysis with an extended time window lasting 4.5 years. We do not find a significant excess in {gamma}-rays for any individual source nor for the combined sources and provide model-independent flux upper limits for both cases. In addition, we derive limits on the {gamma}-ray luminosity and the ratio of {gamma}-ray-to-optical luminosity ratio as a function of the index of the proton injection spectrum assuming a generic {gamma}-ray production model. Furthermore, we present detailed flux predictions based on multi-wavelength observations and the corresponding flux upper limit at a 95% confidence level (CL) for the source SN 2010jl (PTF 10aaxf).
328. Softly X-raying the gamma-ray sky I.
ID:
ivo://CDS.VizieR/J/A+A/631/A150
Title:
Softly X-raying the gamma-ray sky I.
Short Name:
J/A+A/631/A150
Date:
21 Oct 2021
Publisher:
CDS
Description:
BL Lac objects are an extreme type of active galactic nuclei (AGNs) that belong to the largest population of gamma-ray sources: blazars. This class of AGNs shows a double-bumped spectral energy distribution that is commonly described in terms of a synchrotron self-Compton (SSC) emission process, whereas the low-energy component that dominates their emission between the infrared and the X-ray band is tightly connected to the high-energy component that peaks in the gamma-rays. Two strong connections that link radio and mid-infrared emission of blazars to the emission in the gamma-ray band are well established. They constitute the basis for associating gamma-ray sources with their low-energy counterparts. We searched for a possible link between X-ray and gamma-ray emissions for the subclass of BL Lacs using all archival Swift/XRT observations combined with Fermi data for a selected sample of 351 sources. Analyzing ~2400ks of Swift/XRT observations that were carried out until December 2018, we discovered that above the gamma-ray flux threshold Fgamma~=3x10^-12^erg/cm^2^/s, 96% of all Fermi BL Lacs have an X-ray counterpart that is detected with signal-to-noise ratio >3. We did not find any correlation or clear trend between X-ray and gamma-ray fluxes and/or spectral shapes, but we discovered a correlation between the X-ray flux and the mid-infrared color. Finally, we discuss on a possible interpretation of our results in the SSC framework.
329. Sources detected by ISGRI
ID:
ivo://CDS.VizieR/J/A+A/467/585
Title:
Sources detected by ISGRI
Short Name:
J/A+A/467/585
Date:
21 Oct 2021
Publisher:
CDS
Description:
In its first 4 years of observing the sky above 20keV, INTEGRAL-ISGRI has detected 500 sources, around half of which are new or unknown at these energies. Follow-up observations at other wavelengths revealed that some of these sources feature unusually large column densities, long pulsations, and other interesting characteristics. We investigate where new and previously-known sources detected by ISGRI fit in the parameter space of high-energy objects, and we use the parameters to test correlations expected from theoretical predictions. For example, the influence of the local absorbing matter on periodic modulations is studied for Galactic High-Mass X-ray Binaries (HMXBs) with OB supergiant and Be companions. We examine the spatial distribution of different types of sources in the Milky Way using various projections of the Galactic plane, in order to highlight signatures of stellar evolution and to speculate on the origin of the group of sources whose classifications are still uncertain.
330. Spectral analysis of GRBs
ID:
ivo://CDS.VizieR/J/ApJ/720/1146
Title:
Spectral analysis of GRBs
Short Name:
J/ApJ/720/1146
Date:
21 Oct 2021
Publisher:
CDS
Description:
A time-resolved spectral analysis for a sample of 22 intense, broad gamma-ray burst (GRB) pulses from the Compton Gamma Ray Observatory (CGRO)/BATSE GRB sample is presented. We fit the spectra with the Band function and investigate the correlation between the observed flux (F) and the peak energy (E_p_) of the {nu}f_{nu}_ spectrum in the rising and decaying phases of these pulses. Two kinds of E_p_ evolution trends, i.e., hard-to-soft (two-thirds of the pulses in our sample) and E_p_-tracing-F (one-third of the pulses in our sample), are observed in pulses from different GRBs and even from different pulses of the same burst. No dependence of spectral evolution feature on the pulse shape is found. A tight F-E_p_ positive correlation is observed in the decaying phases, with a power-law index ~2.2, which is much shallower than that expected from the curvature effect. In the rising phase, the observed F is either correlated or anti-correlated with E_p_, depending on the spectral evolution feature, and the power-law index of the correlation is dramatically different among pulses. More than 80% of the low-energy photon indices in the time-resolved spectra, whose E_p_'s are anti-correlated with F during the rising phase, violate the death line of the synchrotron radiation, disfavoring the synchrotron radiation model for these gamma rays. The F-E_p_ correlation, especially for those GRBs with E_p_-tracking-F spectral evolution, may be due to the viewing angle and jet structure effects. In this scenario, the observed F-E_p_ correlation in the rising phase may be due to the line of sight toward a structured jet (or jetter) moving from off-beam to on-beam, and both the on-beam emission and the delayed photons from high latitude of the GRB fireball contribute to the decaying phase, resulting in a shallower slope of the observed F-E_p_ correlation than that predicted by the pure curvature effect.