- ID:
- ivo://CDS.VizieR/J/ApJS/217/2
- Title:
- Refined associations of Fermi/LAT sources
- Short Name:
- J/ApJS/217/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released in 2010 February and the Fermi-LAT 2-Year Source Catalog (2FGL) appeared in 2012 April, based on data from 24 months of operation. Since they were released, many follow up observations of unidentified {gamma}-ray sources have been performed and new procedures for associating {gamma}-ray sources with potential counterparts at other wavelengths have been developed. Here we review and characterize all of the associations as published in the 1FGL and 2FGL catalogs on the basis of multifrequency archival observations. In particular, we located 177 spectra for the low-energy counterparts that were not listed in the previous Fermi catalogs, and in addition we present new spectroscopic observations of eight {gamma}-ray blazar candidates. Based on our investigations, we introduce a new counterpart category of "candidate associations" and propose a refined classification for the candidate low-energy counterparts of the Fermi sources. We compare the 1FGL-assigned counterparts with those listed in 2FGL to determine which unassociated sources became associated in later releases of the Fermi catalogs. We also search for potential counterparts to all of the remaining unassociated Fermi sources. Finally, we prepare a refined and merged list of all of the associations of 1FGL plus 2FGL that includes 2219 unique Fermi objects. This is the most comprehensive and systematic study of all the associations collected for the {gamma}-ray sources available to date. We conclude that 80% of the Fermi sources have at least one known plausible {gamma}-ray emitter within their positional uncertainty regions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/489/849
- Title:
- Revised catalogue of EGRET gamma-ray sources
- Short Name:
- J/A+A/489/849
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of point gamma-ray sources detected by the EGRET detector on the Compton Gamma Ray Observatory. We used the entire gamma-ray dataset of reprocessed photons at energies above 100MeV and new Galactic interstellar emission models based on CO, HI, dark gas, and interstellar radiation field data. Two different assumptions are used to describe the cosmic-ray distribution in the Galaxy to analyse the systematic uncertainties in source detection and characterization. We applied a 2-dimensional maximum-likelihood detection method similar to that used to analyze the 3rd EGRET catalogue. The revised catalogue lists 188 sources, 14 of which are marked as confused, in contrast to the 271 entries of the 3rd EGRET (3EG) catalogue. We do not detect 107 sources discovered previously because additional structure is present in the interstellar background.
- ID:
- ivo://CDS.VizieR/J/ApJ/784/159
- Title:
- Revisited jet bending in {gamma}-ray AGNs
- Short Name:
- J/ApJ/784/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the hypothesis that {gamma}-ray-quiet active galactic nuclei (AGNs) have a greater tendency for jet bending than {gamma}-ray-loud AGNs, revisiting the analysis of Tingay et al. We perform a statistical analysis using a large sample of 351 radio-loud AGNs along with {gamma}-ray identifications from the Fermi Large Area Telescope (LAT). Our results show no statistically significant differences in jet-bending properties between {gamma}-ray-loud and {gamma}-ray-quiet populations, indicating that jet bending is not a significant factor for {gamma}-ray detection in AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/489
- Title:
- ROTSE observations of gamma-ray burst afterglows
- Short Name:
- J/ApJ/702/489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a complete set of early optical afterglows of gamma-ray bursts (GRBs) obtained with the Robotic Optical Transient Search Experiment (ROTSE-III) telescope network from 2005 March through 2007 June. This set is comprised of 12 afterglows with early optical and Swift/X-Ray Telescope observations, with a median ROTSE-III response time of 45s after the start of {gamma}-ray emission (8s after the GCN notice time). These afterglows span 4 orders of magnitude in optical luminosity, and the contemporaneous X-ray detections allow multi-wavelength spectral analysis. Excluding X-ray flares, the broadband synchrotron spectra show that the optical and X-ray emission originate in a common region, consistent with predictions of the external forward shock in the fireball model. However, the fireball model is inadequate to predict the temporal decay indices of the early afterglows, even after accounting for possible long-duration continuous energy injection. We find that the optical afterglow is a clean tracer of the forward shock, and we use the peak time of the forward shock to estimate the initial bulk Lorentz factor of the GRB outflow, and find 100<~{Gamma}_0_<~1000, consistent with expectations.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A6
- Title:
- RX J1713.7-3946 HESS spectrum
- Short Name:
- J/A+A/612/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Supernova remnants exhibit shock fronts (shells) that can accelerate charged particles up to very high energies. In the past decade, measurements of a handful of shell-type supernova remnants in very high-energy gamma rays have provided unique insights into the acceleration process. Among those objects, RX J1713.7-3946 (also known as G347.3-0.5) has the largest surface brightness, allowing us in the past to perform the most comprehensive study of morphology and spatially resolved spectra of any such very high-energy gamma-ray source. Here we present extensive new H.E.S.S. measurements of RX J1713.7-3946, almost doubling the observation time compared to our previous publication. Combined with new improved analysis tools, the previous sensitivity is more than doubled. The H.E.S.S. angular resolution of 0.048{deg} (0.036{deg} above 2TeV) is unprecedented in gamma-ray astronomy and probes physical scales of 0.8 (0.6) parsec at the remnant's location. The new H.E.S.S. image of RX J1713.7-3946 allows us to reveal clear morphological differences between X-rays and gamma rays. In particular, for the outer edge of the brightest shell region, we find the first ever indication for particles in the process of leaving the acceleration shock region. By studying the broadband energy spectrum, we furthermore extract properties of the parent particle populations, providing new input to the discussion of the leptonic or hadronic nature of the gamma-ray emission mechanism.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A94
- Title:
- 1RXSJ101015.9-311909 VHE gamma-ray emission
- Short Name:
- J/A+A/542/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 1RXS J101015.9-311909 is a galaxy located at a redshift of z=0.14 hosting an active nucleus (called AGN) belonging to the class of bright BL Lac objects. Observations at high (HE, E>100MeV) and very high (VHE, E>100GeV) energies provide insights into the origin of very energetic particles present in such sources and the radiation processes at work. We report on results from VHE observations performed between 2006 and 2010 with the H.E.S.S. instrument, an array of four imaging atmospheric Cherenkov telescopes. H.E.S.S. data have been analysed with enhanced analysis methods, making the detection of faint sources more significant.
- ID:
- ivo://CDS.VizieR/J/other/RAA/16.13
- Title:
- Sample of Fermi Blazars
- Short Name:
- J/other/RAA/16.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the {gamma}-ray luminosity and beaming effect for Fermi blazars. Our results are as follows. (i) There are significant correlations between {gamma}-ray luminosity and radio core luminosity, and between {gamma}-ray luminosity and Rv, which suggests that the {gamma}-ray emissions have a strong beaming effect. (ii) Using the Lext/Mabs as an indicator of environment effects, we find that there is no significant correlation between {gamma}-ray luminosity and Lext/Mabs for all sources when we remove the effect of redshift. Flat spectrum radio quasars considered alone also do not show a significant correlation, but BL Lacertae objects (BL Lacs) still show a significant correlation when we remove the effect of redshift. These results suggest that the {gamma}-ray emission may be affected by the environment on a kiloparsec scale for BL Lacs.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/75
- Title:
- Search for GW signals associated with GRBs
- Short Name:
- J/ApJ/886/75
- Date:
- 02 Feb 2022 13:41:32
- Publisher:
- CDS
- Description:
- We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of <9.38x10^-6^ (modeled) and 3.1x10^-4^ (unmodeled). We do not find any significant evidence for gravitational-wave signals associated with the other gamma-ray bursts analyzed, and therefore we report lower bounds on the distance to each of these, assuming various source types and signal morphologies. Using our final modeled search results, short gamma-ray burst observations, and assuming binary neutron star progenitors, we place bounds on the rate of short gamma-ray bursts as a function of redshift for z<=1. We estimate 0.07-1.80 joint detections with Fermi-GBM per year for the 2019-20 LIGO-Virgo observing run and 0.15-3.90 per year when current gravitational-wave detectors are operating at their design sensitivities.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A13
- Title:
- Second AGILE catalogue of gamma-ray sources
- Short Name:
- J/A+A/627/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second AGILE-GRID catalogue (2AGL) of gamma-ray sources in the energy range 100MeV-10GeV. With respect to previous AGILE-GRID catalogues, the current 2AGL catalogue is based on the first 2.3 years of science data from the AGILE mission (the so-called pointing mode) and incorporates more data and several analysis improvements, including better calibrations at the event reconstruction level, an updated model for the Galactic diffuse gamma-ray emission, a refined procedure for point-like source detection, and the inclusion of a search for extended gamma-ray sources. The 2AGL catalogue includes 175 high-confidence sources (above 4{sigma} significance) with their location regions and spectral properties and a variability analysis with four-day light curves for the most significant. Relying on the error region of each source position, including systematic uncertainties, 122 sources are considered as positionally associated with known counterparts at different wavelengths or detected by other gamma-ray instruments. Among the identified or associated sources, 62 are active galactic nuclei (AGNs) of the blazar class. Pulsars represent the largest Galactic source class, with 41 associated pulsars, 7 of which have detected pulsation; 8 supernova remnants and 4 high-mass X-ray binaries have also been identified. A substantial number of 2AGL sources are unidentified: for 53 sources no known counterpart is found at different wavelengths. Among these sources, we discuss a subclass of 29 AGILE-GRID-only gamma-ray sources that are not present in 1FGL, 2FGL, or 3FGL catalogues; the remaining sources are unidentified in both 2AGL and 3FGL catalogues. We also present an extension of the analysis of 2AGL sources detected in the energy range 50-100MeV.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/765
- Title:
- Second IBIS/ISGRI soft gamma-ray survey catalog
- Short Name:
- J/ApJ/636/765
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we report the second soft gamma-ray source catalog obtained with the IBIS/ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 10Ms of high-quality observations performed during the first 2 years of Core Program and public IBIS/ISGRI observations, and covers 50% of the whole sky. The main aim of the first survey was to scan systematically, for the first time at energies above 20keV, the whole Galactic plane to achieve a limiting sensitivity of 1mCrab in the central radian. The target of the second year of the INTEGRAL mission lifetime was to expand as much as possible our knowledge of the soft gamma-ray sky, with the same limiting sensitivity, to at least 50% of the whole sky, mainly by including a substantial coverage of extragalactic fields. This catalog comprises more than 200 high-energy sources detected in the energy range 20-100keV, including new transients not active during the first year of operation, faint persistent objects revealed with longer exposure time, and several Galactic and extragalactic sources in sky regions not observed in the first survey. The mean position error for all the sources detected with significance above 10{sigma} is 40", enough to identify most of them with a known X-ray counterpart and to unveil the nature of most of the strongly absorbed ones, even though they are very difficult to detect in X-rays.
