- ID:
- ivo://CDS.VizieR/J/ApJ/742/27
- Title:
- 15GHz and jet properties of MOJAVE blazars
- Short Name:
- J/ApJ/742/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the Fermi Large Area Telescope {gamma}-ray and 15GHz Very Long Baseline Array radio properties of a joint {gamma}-ray and radio-selected sample of active galactic nuclei (AGNs) obtained during the first 11 months of the Fermi mission (2008 August 4-2009 July 5). Our sample contains the brightest 173 AGNs in these bands above declination -30{deg} during this period, and thus probes the full range of {gamma}-ray loudness ({gamma}-ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least 4 orders of magnitude, reflecting a wide range of spectral energy distribution (SED) parameters in the bright blazar population. The BL Lac objects, however, display a linear correlation of increasing {gamma}-ray loudness with synchrotron SED peak frequency, suggesting a universal SED shape for objects of this class.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/438/3058
- Title:
- 15GHz variability of {gamma}-ray blazars
- Short Name:
- J/MNRAS/438/3058
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from four years of twice-weekly 15GHz radio monitoring of about 1500 blazars with the Owens Valley Radio Observatory 40m telescope. Using the intrinsic modulation index to measure variability amplitude, we find that, with >6{sigma} significance, the radio variability of radio-selected {gamma}-ray-loud blazars is stronger than that of {gamma}-ray-quiet blazars. Our extended data set also includes at least 21 months of data for all AGN with 'clean' associations in the Fermi Large Area Telescope First AGN Catalog, 1LAC. With these additional data, we examine the radio variability properties of a {gamma}-ray-selected blazar sample. Within this sample, we find no evidence for a connection between radio variability amplitude and optical classification. In contrast, for our radio-selected sample we find that the BL Lac object subpopulation is more variable than the flat-spectrum radio quasar (FSRQ) subpopulation. Radio variability is found to correlate with the synchrotron peak frequency, with low- and intermediate-synchrotron-peaked blazars varying more than high-synchrotron-peaked ones. We find evidence for a significant negative correlation between redshift and radio variability among bright FSRQs.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A31
- Title:
- G29.37+0.1 610MHz image
- Short Name:
- J/A+A/602/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the first detailed multiwavelength study of the radio source G29.37+0.1, which is an as-yet-unclassified object linked to the very-high-energy gamma-emitting source HESS J1844-030. The origin of the multiwavelength emission toward G29.37+0.1 has not been clarified so far, leaving open the question about the physical relationship between these sources. Using observations carried out with the Giant Metrewave Radio Telescope (GMRT), we performed high-quality full-synthesis imaging at 610MHz of the field containing G29.37+0.1. The obtained data, combined with observations at 1400MHz from the MAGPIS were used to investigate in detail the properties of its radio emission. Additionally, we reprocessed archival data obtained with the XMM-Newton and Chandra observatories in order to get a multiwavelength view of this unusual source. The radio source G29.37+0.1 mainly consists of a bright twisted structure, named the S-shaped feature. The high sensitivity of the new GMRT observations allowed the identification of potential lobes, jets and a nuclear central region in the S-shaped morphology of G29.37+0.1. We also highlight the detection of diffuse and low surface brightness emission enveloping the brightest emitting regions. The brightest emission in G29.37+0.1 has a radio synchrotron spectral index alpha=0.59+/-0.09. Variations in the spectral behaviour are observed across the whole radio source with the flattest spectral features in the central nuclear and jets components (alpha~0.3). These results lead us to conclude that the brightest radio emission from G29.37+0.1 likely represents a newly recognized radio galaxy. The identification of optical and infrared counterparts to the emission arising from the core of G29.37+0.1 strengthens our interpretation of an extragalactic origin of the radio emission. We performed several tests to explain the physical mechanism responsible for the observed X-ray emission, which appears overlapping the northeastern part of the radio emission. Our spectral analysis demonstrated that a non-thermal origin for the X-ray emission compatible with a pulsar wind nebula is quite possible. The analysis of the spatial distribution of the CO gas revealed the presence of a complex of molecular clouds located in projection adjacent to the radio halo emission and probably interacting with it. We propose that the faint halo represents a composite supernova remnant with a pulsar powered component given by the diffuse X-ray emission superimposed along the line of sight to the radio galaxy. Further broadband observations of HESS J1844-030 are needed to disentangle its origin, although its shape and position suggest an extragalactic origin connected to G29.37+0.1.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A80
- Title:
- GMVA 86GHz images of OJ 287
- Short Name:
- J/A+A/597/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The gamma-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features, including an apparent (~100{deg}) position-angle change in projection on the sky plane. Sub-50 micro-arcsecond resolution 86GHz observations with the global mm-VLBI array (GMVA) supplement ongoing multifrequency VLBI blazar monitoring at lower frequencies. Using these maps, together with cm/mm total intensity and gamma-ray observations from Fermi/LAT from 2008-2014, we aim to determine the location of gamma-ray emission and to explain the inner-mas structural changes. Observations with the GMVA offset approximately double the angular resolution compared with 43GHz VLBA observations and enable us to observe above the synchrotron self-absorption peak frequency. Fermi-LAT gamma-ray data were reduced and analysed. The jet was spectrally decomposed at multiple locations along the jet. From this, we could derive estimates of the magnetic field using equipartition and synchrotron self-absorption arguments. How the field decreases down the jet provided an estimate of the distance to the jet apex and an estimate of the magnetic field strength at the jet apex and in the broad line region. Combined with accurate kinematics, we attempt to locate the site of gamma-ray activity, radio flares, and spectral changes.
- ID:
- ivo://CDS.VizieR/J/ApJ/715/1438
- Title:
- Gravitational-wave bursts with GRBs
- Short Name:
- J/ApJ/715/1438
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for gravitational-wave bursts (GWBs) associated with 137 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments during the fifth LIGO science run and first Virgo science run. The data used in this analysis were collected from 2005 November 4 to 2007 October 1, and most of the GRB triggers were from the Swift satellite. The search uses a coherent network analysis method that takes into account the different locations and orientations of the interferometers at the three LIGO-Virgo sites. We find no evidence for GWB signals associated with this sample of GRBs. Using simulated short-duration (<1s) waveforms, we set upper limits on the amplitude of gravitational waves associated with each GRB. We also place lower bounds on the distance to each GRB under the assumption of a fixed energy emission in gravitational waves, with a median limit of D~12Mpc(E^iso^_GW_/0.01M_{sun}_c^2^)^1/2^ for emission at frequencies around 150Hz, where the LIGO-Virgo detector network has best sensitivity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/1874
- Title:
- GRB 100901A and GRB 100906A light curves
- Short Name:
- J/MNRAS/421/1874
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the prompt, early and afterglow optical observations of five {gamma}-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/169/62
- Title:
- GRB database of spectral lags
- Short Name:
- J/ApJS/169/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a database of spectral lags and internal luminosity function (ILF) measurements for gamma-ray bursts (GRBs) in the BATSE catalog. Measurements were made using 64ms count rate data and are defined for various combinations of the four broadband BATSE energy channels.
- ID:
- ivo://CDS.VizieR/J/ApJ/778/128
- Title:
- GRB-host galaxies photometry
- Short Name:
- J/ApJ/778/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations and analysis of the host galaxies of 23 heavily dust-obscured gamma-ray bursts (GRBs) observed by the Swift satellite during the years 2005-2009, representing all GRBs with an unambiguous host-frame extinction of A_V_>1mag from this period. Deep observations with Keck, Gemini, Very Large Telescope, Hubble Space Telescope, and Spitzer successfully detect the host galaxies and establish spectroscopic or photometric redshifts for all 23 events, enabling us to provide measurements of the intrinsic host star formation rates, stellar masses, and mean extinctions. Compared to the hosts of unobscured GRBs at similar redshifts, we find that the hosts of dust-obscured GRBs are (on average) more massive by about an order of magnitude and also more rapidly star forming and dust obscured. While this demonstrates that GRBs populate all types of star-forming galaxies, including the most massive, luminous systems at z{approx}2, at redshifts below 1.5 the overall GRB population continues to show a highly significant aversion to massive galaxies and a preference for low-mass systems relative to what would be expected given a purely star-formation-rate-selected galaxy sample. This supports the notion that the GRB rate is strongly dependent on metallicity, and may suggest that the most massive galaxies in the universe underwent a transition in their chemical properties ~9Gyr ago. We also conclude that, based on the absence of unobscured GRBs in massive galaxies and the absence of obscured GRBs in low-mass galaxies, the dust distributions of the lowest-mass and the highest-mass galaxies are relatively homogeneous, while intermediate-mass galaxies (~10^9^M_{sun}_) have diverse internal properties.
- ID:
- ivo://CDS.VizieR/J/A+A/607/A107
- Title:
- GRB 080810 Keck/HIRES spectrum
- Short Name:
- J/A+A/607/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We reveal multiple components of an interacting galaxy system at z~3.35 through a detailed analysis of the exquisite high-resolution Keck/HIRES spectrum of the afterglow of a gamma-ray burst (GRB). Through Voigt-profile fitting of absorption lines from the Lyman-series, we constrain the neutral hydrogen column density to N_HI_<=10^18.35^cm^-2^ for the densest of four distinct systems at the host redshift of GRB 080810, among the lowest NHI ever observed in a GRB host, despite the line of sight passing within a projected 5kpc of the galaxy centres. By detailed analysis of the corresponding metal absorption lines, we derive chemical, ionic and kinematic properties of the individual absorbing systems, and thus build a picture of the host as a whole. Striking differences between the systems imply that the line of sight passes through several phases of gas: the star-forming regions of the GRB host; enriched material in the form of a galactic outflow; the hot and ionised halo of a second, interacting galaxy falling towards the host at a line-of-sight velocity of 700km/s; and a cool, metal-poor cloud which may represent one of the best candidates yet for the inflow of metal-poor gas from the intergalactic medium.
- ID:
- ivo://CDS.VizieR/J/ApJ/828/36
- Title:
- GRB light-curve decay indices with Swift
- Short Name:
- J/ApJ/828/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we study the distribution of temporal power-law decay indices, {alpha}, in the gamma-ray burst (GRB) afterglow phase, fitted for 176 GRBs (139 long GRBs, 12 short GRBs with extended emission, and 25 X-ray flashes) with known redshifts. These indices are compared with the temporal decay index, {alpha}_W_, derived with the light-curve fitting using the Willingale+ (2007ApJ...662.1093W) model. This model fitting yields similar distributions of {alpha}_W_ to the fitted {alpha}, but for individual bursts a difference can be significant. Analysis of ({alpha}, L_a_) distribution, where L_a_ is the characteristic luminosity at the end of the plateau, reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB {alpha} values along the Dainotti+ (2013ApJ...774..157D) correlation between L_a_ and the end time of the plateau emission in the rest frame, T_a_^*^, hereafter LT correlation. We note a systematic variation of the {alpha} parameter distribution with luminosity for any selected T_a_^*^. We analyze this systematics with respect to the fitted LT correlation line, expecting that the presented trend may allow us to constrain the GRB physical models. We also attempted to use the derived correlation of {alpha}(T_a_) versus L_a_(T_a_) to diminish the luminosity scatter related to the variations of {alpha} along the LT distribution, a step forward in the effort of standardizing GRBs. A proposed toy model accounting for this systematics applied to the analyzed GRB distribution results in a slight increase of the LT correlation coefficient.
