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- ID:
- ivo://CDS.VizieR/J/A+A/636/A62
- Title:
- Light curves of 3C273 during 2015-2019
- Short Name:
- J/A+A/636/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The powerful radiation over the entire electromagnetic spectrum and its radio jet activity of the blazar 3C 273 offer the opportunity of studying the physics of {gamma}-ray emission from active galactic nuclei. Since the historically strong outburst in 2009, 3C 273 showed relatively weak emission in the {gamma}-ray band over several years. However, recent Fermi-Large Area Telescope observations indicate higher activity during 2015-2019. We constrain the origin of the {gamma}-ray outbursts toward 3C 273 and investigate their connection to the parsec-scale jet. We generated Fermi-LAT {gamma}-ray light curves with multiple binning intervals and studied the spectral properties of the {gamma}-ray emission. Using a 3mm ALMA light curve, we studied the correlation between radio and {gamma}-ray emission. The relevant activity in the parsec-scale jet of 3C 273 was investigated with 7 mm VLBA observations that were obtained close in time to notable {gamma}-ray outbursts. We find two prominent {gamma}-ray outbursts in 2016 (MJD 57382) and 2017 (MJD 57883) accompanied by millimeter-wavelength flaring activity. The {gamma}-ray photon index time series show a weak hump-like feature around the {gamma}-ray outbursts. The monthly {gamma}-ray flux-index plot indicates a transition from softer-when-brighter to harder-when-brighter states at 1.03x10^-7^ph/cm^2^/s. A significant correlation between the {gamma}-ray and millimeter-wavelength emission is found, and the radio lags the {gamma}-rays by about 105-112 days. The 43GHz jet images reveal the known stationary features (i.e., the core, S1, and S2) in a region upstream of the jet. We find an indication for a propagating disturbance and a polarized knot between the stationary components at about the times of the two {gamma}-ray outbursts. Our results support a parsec-scale origin for the observed higher {gamma}-ray activity, which suggests that this is associated with standing shocks in the jet.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/12
- Title:
- LIGO/Virgo gravitational-wave (GW) bursts with GRBs
- Short Name:
- J/ApJ/760/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for gravitational waves associated with 154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments in 2009-2010, during the sixth LIGO science run and the second and third Virgo science runs. We perform two distinct searches: a modeled search for coalescences of either two neutron stars or a neutron star and black hole, and a search for generic, unmodeled gravitational-wave bursts. We find no evidence for gravitational-wave counterparts, either with any individual GRB in this sample or with the population as a whole. For all GRBs we place lower bounds on the distance to the progenitor, under the optimistic assumption of a gravitational-wave emission energy of 10^-2^M_{sun}_c^2^ at 150Hz, with a median limit of 17Mpc. For short-hard GRBs we place exclusion distances on binary neutron star and neutron-star-black-hole progenitors, using astrophysically motivated priors on the source parameters, with median values of 16Mpc and 28Mpc, respectively. These distance limits, while significantly larger than for a search that is not aided by GRB satellite observations, are not large enough to expect a coincidence with a GRB. However, projecting these exclusions to the sensitivities of Advanced LIGO and Virgo, which should begin operation in 2015, we find that the detection of gravitational waves associated with GRBs will become quite possible.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/L21
- Title:
- Limits on gamma-ray emission from galaxy clusters
- Short Name:
- J/ApJ/795/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy clusters are predicted to produce {gamma}-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z<0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3x10^-11^ photons/cm2/s (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5x10^44^ photons/s. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and {gamma}-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.
235. List of 389 GRBs
- ID:
- ivo://CDS.VizieR/J/A+A/582/A111
- Title:
- List of 389 GRBs
- Short Name:
- J/A+A/582/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of a statistically significant clustering in the distribution of gamma-ray bursts (GRBs) has recently been reported. Given that the cluster has a characteristic size of 2000-3000Mpc and a redshift between 1.6<=z<=2.1, it has been claimed that this structure is incompatible with the cosmological principle of homogeneity and isotropy of our Universe. In this paper, we study the homogeneity of the GRB distribution using a subsample of the Greiner GRB catalogue, which contains 314 objects with redshift 0<z<2.5 (244 of them discovered by the Swift GRB mission). We try to reconcile the dilemma between the new observations and the current theory of structure formation and growth. To test the results against the possible biases in redshift determination and the incompleteness of the Greiner sample, we also apply our analysis to the 244 GRBs discovered by Swift and the subsample presented by the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS). The real space two-point correlation function (2PCF) of GRBs, {ksi}(r), is calculated using a Landy-Szalay estimator. We perform a standard least-{Chi}^2^ fit to the measured 2PCFs of GRBs. We use the best-fit 2PCF to deduce a recently defined homogeneity scale. The homogeneity scale, R_H_, is defined as the comoving radius of the sphere inside which the number of GRBs N(<r) is proportional to r^3^ within 1%, or equivalently above which the correlation dimension of the sample D^2^ is within 1% of D^2^=3.
236. List of GRBs
- ID:
- ivo://CDS.VizieR/J/A+A/427/87
- Title:
- List of GRBs
- Short Name:
- J/A+A/427/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss INTEGRAL's ability to detect a high redshift population of Gamma-Ray Bursts (GRBs) in comparison to other high-energy missions. Emphasis is placed on the study of the relative capabilities of IBIS on board INTEGRAL with respect to SWIFT and HETE 2 in detecting a high redshift population of GRBs. We conclude that, if the GRB rate is proportional to the star formation rate, INTEGRAL's ability to study GRBs are complementary to the ones of missions like SWIFT and HETE 2, devoted to prompt localisations of GRBs. Whereas SWIFT and HETE 2 would detect a higher number of GRBs than INTEGRAL, IBIS might be able to detect high redshift (z>~7) GRBs, unreachable by SWIFT and HETE 2. We discuss the relevance of performing near-infrared (NIR) observations of the INTEGRAL GRBs and the strategy that large-class telescopes might follow.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/2624
- Title:
- List of isolated emission episodes in GRB
- Short Name:
- J/MNRAS/448/2624
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a comprehensive catalogue of emission episodes within long gamma-ray bursts (GRBs) that are separated by a quiescent period during which gamma-ray emission falls below the background level. We use a fully automated identification method for an unbiased, large-scale and expandable search. We examine a comprehensive sample of long GRBs from the BATSE (Burst and Transient Source Experiment), Swift and Fermi missions, assembling a total searched set of 2710 GRBs, the largest catalogue of isolated emission episodes so far. Our search extends out to [-1000s,750s] around the burst trigger, expanding the covered time interval beyond previous studies and far beyond the nominal durations (T_90_) of most bursts. We compare our results to previous works by identifying pre-peak emission (or precursors), defined as isolated emission periods prior to the episode with the highest peak luminosity of the burst. We also systematically search for similarly defined periods after the burst's peak emission. We find that the pre-peak and post-peak emission periods are statistically similar, possibly indicating a common origin. For the analysed GRBs, we identify 24 percent to have more than one isolated emission episode, with 11 percent having at least one pre-peak event and 15 percent having at least one post-peak event. We identify GRB activity significantly beyond their T_90_, which can be important for understanding the central engine activity as well as, e.g. gravitational-wave searches.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/L21
- Title:
- List of Telescope Array events with E > 57EeV
- Short Name:
- J/ApJ/790/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched for intermediate-scale anisotropy in the arrival directions of ultrahigh-energy cosmic rays with energies above 57 EeV in the northern sky using data collected over a 5 yr period by the surface detector of the Telescope Array experiment. We report on a cluster of events that we call the hotspot, found by oversampling using 20{deg} radius circles. The hotspot has a Li-Ma statistical significance of 5.1{sigma}, and is centered at RA = 146.{deg}7, DE = 43.{deg}2. The position of the hotspot is about 19{deg} off of the supergalactic plane. The probability of a cluster of events of 5.1{sigma} significance, appearing by chance in an isotropic cosmic-ray sky, is estimated to be 3.7x10^-4^ (3.4{sigma}).
- ID:
- ivo://CDS.VizieR/J/A+A/586/A71
- Title:
- LMC 0.2-100GeV images
- Short Name:
- J/A+A/586/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in {gamma}-rays. The LMC was detected at 0.1-100GeV as an extended source with CGRO/EGRET and using early observations with the Fermi-LAT. The emission was found to correlate with massive star-forming regions and to be particularly bright towards 30 Doradus. Studies of the origin and transport of cosmic rays (CRs) in the Milky Way are frequently hampered by line-of-sight confusion and poor distance determination. The LMC offers a complementary way to address these questions by revealing whether and how the {gamma}-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. We revisited the {gamma}-ray emission from the LMC using about 73 months of Fermi-LAT P7REP data in the 0.2-100GeV range. We developed a complete spatial and spectral model of the LMC emission, for which we tested several approaches: a simple geometrical description, template-fitting, and a physically driven model for CR-induced interstellar emission.
- ID:
- ivo://CDS.VizieR/J/ApJS/216/32
- Title:
- Localizations of GRBs with Fermi GBM
- Short Name:
- J/ApJS/216/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network, to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1{deg}, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.{deg}7 Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14{deg}. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y axis better localized than those on the X axis.
