- ID:
- ivo://CDS.VizieR/J/ApJ/799/86
- Title:
- Isotropic diffuse gamma-ray emission 0.1-820GeV
- Short Name:
- J/ApJ/799/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {gamma}-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse {gamma}-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200MeV and 100GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100MeV to 820GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32+/-0.02 and a break energy of (279+/-52)GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2+/-0.6)x10^-6^/cm2/s/sr above 100MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.
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- ID:
- ivo://CDS.VizieR/J/ApJ/818/18
- Title:
- Jet angles and gamma-ray energetics estimations
- Short Name:
- J/ApJ/818/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method to estimate the jet opening angles of long duration gamma-ray bursts (GRBs) using the prompt gamma-ray energetics and an inversion of the Ghirlanda relation, which is a correlation between the time-integrated peak energy of the GRB prompt spectrum and the collimation-corrected energy in gamma-rays. The derived jet opening angles using this method and detailed assumptions match well with the corresponding inferred jet opening angles obtained when a break in the afterglow is observed. Furthermore, using a model of the predicted long GRB redshift probability distribution observable by the Fermi Gamma-ray Burst Monitor (GBM), we estimate the probability distributions for the jet opening angle and rest-frame energetics for a large sample of GBM GRBs for which the redshifts have not been observed. Previous studies have only used a handful of GRBs to estimate these properties due to the paucity of observed afterglow jet breaks, spectroscopic redshifts, and comprehensive prompt gamma-ray observations, and we potentially expand the number of GRBs that can be used in this analysis by more than an order of magnitude. In this analysis, we also present an inferred distribution of jet breaks which indicates that a large fraction of jet breaks are not observable with current instrumentation and observing strategies. We present simple parameterizations for the jet angle, energetics, and jet break distributions so that they may be used in future studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/98
- Title:
- Jet kinematics of blazars at 43GHz with the VLBA
- Short Name:
- J/ApJ/846/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of {gamma}-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BL Lacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02c to 78c; 21% of the knots are quasi-stationary. Approximately one-third of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5pc (projected) of the core, and knots in BLLacs tending to decelerate near the core. Using the apparent speeds of the components and the timescales of variability from their light curves, we derive the physical parameters of 120 superluminal knots, including variability Doppler factors, Lorentz factors, and viewing angles. We estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. We determine characteristic values of the physical parameters for each jet and active galactic nucleus class based on the range of values obtained for individual features. We calculate the intrinsic brightness temperatures of the cores, T_b,int_^core^, at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while ~30% of T_b,int_^core^ measurements in the quasars and BLLacs deviate from equipartition values by a factor >10. This probably occurs during transient events connected with active states.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/39
- Title:
- Jet properties of {gamma}-ray-loud 3FGL AGNs
- Short Name:
- J/ApJS/235/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on broadband spectral energy distributions (SEDs), we estimate the jet physical parameters of 1392 {gamma}-ray-loud active galactic nuclei (AGNs), the largest sample so far. The (SED) jet power and magnetization parameter are derived for these AGNs. Out of these sources, the accretion disk luminosity of 232 sources and (extended) kinetic jet powers of 159 sources are compiled from archived papers. We find the following. (1) Flat-spectrum radio quasars (FSRQs) and BL Lacs are well separated by {Gamma}=-0.127logL_{gamma}_+8.18 in the {gamma}-ray luminosity versus photon index plane with a success rate of 88.6%. (2) Most FSRQs present a (SED) jet power larger than the accretion power, which suggests that the relativistic jet-launching mechanism is dominated by the Blandford-Znajek process. This result confirms previous findings. (3) There is a significant anticorrelation between jet magnetization and a ratio of the (SED) jet power to the (extended) kinetic jet power, which, for the first time, provides supporting evidence for the jet energy transportation theory: a high- magnetization jet may more easily transport energy to a large scale than a low-magnetization jet.
- ID:
- ivo://CDS.VizieR/J/ApJ/491/93
- Title:
- JHK photometry of 9 gamma-ray burst fields
- Short Name:
- J/ApJ/491/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of a deep, near-infrared survey of a predetermined, consistent sample of gamma-ray burst localizations are presented. This systematic study, conducted from 1994 to 1996, is the first to be designed specifically to examine the extragalactic content of these regions of sky. JHK images of nine of the smallest error boxes from the third Interplanetary Network together with 70arcmin^2^ of control fields were obtained reaching levels up to 200 times fainter than those reached by previous infrared studies of burst locations. Photometric measurements and star/galaxy separation measurements of more than 3000 detected objects were made. An overabundance of brighter galaxies exists in the gamma-ray burst images at the 98% confidence level, which indicates that the bursts are cosmological. Both the level of this enhancement and the galaxy brightness, where it appears, match what is expected for host galaxies. As a group, the brightest galaxy within each error box is slightly brighter than normal but is still consistent with a random population of galaxies. Their positions within the boxes are also consistent with a random distribution, with no preference toward the center. The bright galaxy excess in these regions of sky, combined with a seemingly random population of brightest error box galaxies, suggest that either the true host galaxies are fainter or the error boxes do not point accurately to the hosts.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/L9
- Title:
- 1.5Jy MOJAVE AGN sample and 3FGL data
- Short Name:
- J/ApJ/810/L9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the complete MOJAVE 1.5Jy sample of active galactic nuclei (AGNs) to examine the gamma-ray detection statistics of the brightest radio-loud blazars in the northern sky. We find that 23% of these AGNs were not detected above 0.1GeV by the Fermi-LAT during the four-year 3FGL catalog period partly because of an instrumental selection effect and partly due to their lower Doppler boosting factors. Blazars with synchrotron peaks in their spectral energy distributions located below 10^13.4^Hz also tend to have high-energy peaks that lie below the 0.1GeV threshold of the LAT, and are thus less likely to be detected by Fermi. The non-detected AGNs in the 1.5Jy sample also have significantly lower 15GHz radio modulation indices and apparent jet speeds, indicating that they have lower than average Doppler factors. Since the effective amount of relativistic Doppler boosting is enhanced in gamma-rays (particularly in the case of external inverse-Compton scattering), this makes them less likely to appear in the 3FGL catalog. Based on their observed properties, we have identified several bright radio-selected blazars that are strong candidates for future detection by Fermi.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/161
- Title:
- Konus-Wind cat. of GRBs with redshifts. I.
- Short Name:
- J/ApJ/850/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this catalog, we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected in the triggered mode of the Konus-Wind (KW) experiment during the period from 1997 February to 2016 June. The sample consists of 150 GRBs (including 12 short/hard bursts) and represents the largest set of cosmological GRBs studied to date over a broad energy band. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with two model functions, the total energy fluences, and the peak energy fluxes. Based on the GRB redshifts, which span the range 0.1<=z<=5, we estimate the rest-frame, isotropic-equivalent energy, and peak luminosity. For 32 GRBs with reasonably constrained jet breaks, we provide the collimation- corrected values of the energetics. We consider the behavior of the rest-frame GRB parameters in the hardness-duration and hardness-intensity planes, and confirm the "Amati" and "Yonetoku" relations for Type II GRBs. The correction for the jet collimation does not improve these correlations for the KW sample. We discuss the influence of instrumental selection effects on the GRB parameter distributions and estimate the KW GRB detection horizon, which extends to z~16.6, stressing the importance of GRBs as probes of the early universe. Accounting for the instrumental bias, we estimate the KW GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which are in general agreement with those obtained in previous studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/159
- Title:
- Late X-ray emission of binary-driven hypernovae
- Short Name:
- J/ApJ/833/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has previously been discovered that there is a universal power-law behavior exhibited by the late X-ray emission (LXRE) of a "golden sample" of six long energetic GRBs, when observed in the rest frame of the source. This remarkable feature, independent of the different isotropic energy (E_iso_) of each GRB, has been used to estimate the cosmological redshift of some long GRBs. This analysis is extended here to a new class of 161 long GRBs, all with E_iso_>10^52^erg. These GRBs are indicated as binary-driven hypernovae (BdHNe) in view of their progenitors: a tight binary system composed of a carbon-oxygen core (CO_core_) and a neutron star undergoing an induced gravitational collapse (IGC) to a black hole triggered by the CO_core_ explosion as a supernova (SN).
- ID:
- ivo://CDS.VizieR/J/ApJ/903/33
- Title:
- 1366 LGRB redshifts estimates with BARSE
- Short Name:
- J/ApJ/903/33
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We present a catalog of probabilistic redshift estimates for 1366 individual Long-duration Gamma-ray Bursts (LGRBs) detected by the Burst And Transient Source Experiment (BATSE). This result is based on a careful selection and modeling of the population distribution of 1366 BATSE LGRBs in the five-dimensional space of redshift and the four intrinsic prompt gamma-ray emission properties: the isotropic 1024ms peak luminosity (L_iso_), the total isotropic emission (E_iso_), the spectral peak energy (E_pz_), as well as the intrinsic duration (T_90z_), while carefully taking into account the effects of sample incompleteness and the LGRB-detection mechanism of BATSE. Two fundamental plausible assumptions underlie our purely probabilistic approach: (1) LGRBs trace, either exactly or closely, the cosmic star formation rate, with a possibility of the excess rates of LGRBs in the nearby universe, and (2) the joint four-dimensional distribution of the aforementioned prompt gamma-ray emission properties is well described by a multivariate log-normal distribution. Our modeling approach enables us to constrain the redshifts of individual BATSE LGRBs to within 0.36 and 0.96 average uncertainty ranges at 50% and 90% confidence levels, respectively. Our redshift predictions are completely at odds with the previous redshift estimates of BATSE LGRBs that were computed via the proposed phenomenological high-energy relations, specifically, the apparently strong correlation of LGRBs' peak luminosity with the spectral peak energy, lightcurve variability, and spectral lag. The observed discrepancies between our predictions and the previous works can be explained by the strong influence of detector threshold and sample incompleteness in shaping these phenomenologically proposed high-energy correlations in the literature. Finally, we also discuss the potential effects of an excess cosmic rate of LGRBs at low redshifts and the possibility of a luminosity evolution of LGRBs on our results.
- ID:
- ivo://CDS.VizieR/J/ApJ/654/L25
- Title:
- Light-curve data for GRB 050319
- Short Name:
- J/ApJ/654/L25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiwavelength observations of the optical afterglow of GRB 050319 were performed from 1.31 to 9.92hr after the burst. Our R-band light curves, combined with other published data, can be described by the smooth broken power-law function, with {alpha}_1_=-0.84+/-0.02 to {alpha}_2_=-0.48+/-0.03, 0.04 days after the gamma-ray burst. The optical light curves are characterized by shallow decays as was also observed in the X-rays which may have a similar origin, related to energy injection. However, our observations indicate that there is still a puzzle concerning the chromatic breaks in the R-band light curve (at 0.04 days) and the X-ray light curve (at 0.004 days) that remains to be solved.
