An accurate census of the active galactic nuclei (AGN) is a key step in investigating the nature of the correlation between the growth and evolution of super massive black holes and galaxy evolution. X-ray surveys provide one of the most efficient ways of selecting AGN.
The Swift Galactic Plane Survey team report the detection of 248 point-like X-ray sources (0.3-10keV) in observations covering the final 40% of our survey area (see also 2012ATel.3951....1R and 2012ATel.4318....1R). The listed sources are those we consider to be robust detections at the current time.
Swift Gamma Ray Burst Compilation by Burst Advocate
Short Name:
SWIFTGRBBA
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This database table includes the early results published in the Gamma-Ray Burst Coordinates Network (GCN) circulars on GRBs detected by the Swift observatory and GRBs detected first by other observatories and followed by Swift. The Swift observatory has a rapid (minute timescale) response to GRB detection and performs sensitive X-ray and optical afterglow observations of hundreds of GRBs on all timescales, from minutes to even months later. The instrumentation consists in a large field of view (FOV) instrument, the Burst Alert Telescope (BAT, 15-150 keV) and two narrow field of view instruments, the Ultraviolet/Optical Telescope (UVOT) and the X-ray Telescope (XRT). The BAT searches the sky for gamma-ray bursts (GRBs), determines their location with a precision of a few arcminutes, and triggers an autonomous spacecraft slew to place the burst in the FOV of the narrow field instruments. The first-look data from the three Swift instruments for a newly discovered GRB and its afterglow are transmitted to the ground via TDRSS. The complete telemetry (including the messages transmitted via TDRSS) is subsequently sent down via the Malindi ground station. The information transmitted via TDRSS are broadcast via the the Gamma-Ray Burst Coordinates Network (GCN) followed by subsequent GCN circular based on the early ground analysis of the data collected by Malindi. If the GRB is triggered by Swift , this table records the initial characteristic associated to a burst obtained with the data coming via TDRSS and initial data downloaded via Malindi which results are published via the GCN. In addition the table reports other burst characteristics as for redshift obtained by observations with ground observatories. If the GRB is detected first by other observatories, the table reports results obtained with the ground analysis of the Malindi data and published via the GCN. This database table is generated by compiling the results of the GCN circulars. It was added to the HEASARC database in March 2025. During operation, it is updated weekly and/or for any new trigger. This table is also available at <a href="https://swift.gsfc.nasa.gov/archive/grb_table/">https://swift.gsfc.nasa.gov/archive/grb_table/</a>. This is a service provided by NASA HEASARC .
This table contains the results of the Gamma Ray Bursts (GRBs) observed by Swift. The GRBs included are either triggered by Swift or follow-ups of GRBs discovered by other satellites. The table reports results and/or information, when possible, for each burst from all three instruments on board Swift, e.g. the Bursts Alert Telescope, BAT,the X-ray Telescope, XRT, and the Ultra-Violet Optical Telescope, UVOT. The results are obtained from a standard analysis processing of the Swift data which creates several data products available via this table. Additional information on the burst either from Gamma-ray and X-ray observations or results from ground-based telescopes are extracted from the GCN and the BAT Burst catalog. This table's data products are also available from the dedicated web pages <a href="http://heasarc.gsfc.nasa.gov/docs/swift/archive/grbsummary/">http://heasarc.gsfc.nasa.gov/docs/swift/archive/grbsummary/</a>. The current database contains all bursts observed by Swift from the beginning of the mission, 20 Nov 2004 up to 31 Dec 2012. The data products are available for Bursts detected after 15 Feb 2005. This online catalog was created by the HEASARC based on machine-readable tables compiled by the HEASARC staff. Details are published in Donato et al. (2012). This is a service provided by NASA HEASARC .
Swift Gamma-ray Urgent Archiver for Novel Opportunities (GUANO) Events
Short Name:
SWIFTGUANO
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Swift Observatory provides event-level data from the Burst Alert Telescope (BAT) on demand in response to transients detected by other observatories/instruments. This capability, named "Gamma-ray Urgent Archiver for Novel Opportunities" (GUANO), was introduced in 2020. In normal operations, BAT records the arrival time (to 100-microsecond accuracy), location (in detector coordinates), and energy (in one of 80 bins from 15 to 350 keV) for each individual count that strikes the detector. These data, referred as event-by-event (or event), because of the large effective area of the BAT, produces a large data volume that cannot all be stored onboard or telemetered to the ground. For this reason, the BAT has relied on the performance of its onboard real-time detection algorithms, and only preserves event data and telemeters them to the ground around the time of events that trigger these onboard algorithms. The GUANO implementation allows to download BAT event data that did not trigger on board. Upon receiving an alert from different observatories, an autonomous spacecraft-commanding pipeline requests to download from the Swift satellite the BAT event data around the time of the GUANO event with a time window, typically around 200 seconds. The satellite does not slew; therefore, only BAT event data are available for the GUANO event and these data are tagged with a sequence number associated with the ongoing observation containing the GUANO time window. This table records the times of the GUANO events from different observatories from which Swift was able to download the BAT event data together with the directory and file names where the event are located in the archive. There is one record for each trigger by an external observatory that requested BAT event data; therefore, it is possible that multiple records are associated with the same event. This contents of this database table are generated at the Swift processing site. During operation, it is updated for any new GUANO trigger. These updates are then delivered to the HEASARC and ingested into the HEASARC database in a timely fashion. Note that some parameters (specifically, the galactic coordinates) have been added and are populated by the HEASARC. This is a service provided by NASA HEASARC .
When a massive star explodes as a gamma-ray burst (GRB), information about the explosion is retained in the properties of the prompt and afterglow emission. We report on new relations between the prompt and X-ray afterglow emission of Swift-detected GRBs found from Burst Alert Telescope (BAT) and X-Ray Telescope data covering 2004 December to 2013 August (754 in total). These relations suggest that the prompt and afterglow emission are closely linked. In particular, we find very strong correlations between the BAT 15-150keV T_90_ and the break times before and after the plateau phase in the 0.3-10keV X-ray afterglow light curves. We also find a strong anticorrelation between the photon index of the GRB prompt emission and the X-ray spectral slope of the afterglow. Moreover, anticorrelations exist between the rest-frame peak energy in the prompt emission E_peak, z_and the X-ray afterglow decay slope during the plateau phase and the break times after the plateau phase. The rest-frame break times before and after the plateau phase are also anticorrelated with the rest-frame 15-150keV luminosity and the isotropic energy during the prompt emission. A principal component analysis suggests that the GRB properties are primarily driven by the luminosity/energy release in the 15-150keV band. Luminosity functions derived at different redshifts from a log N-log S analysis indicate that the density of bright bursts is significantly lower in the local universe than in the universe at z~3, where the density of bright GRBs peaks. Using cluster analysis, we find that the duration of BAT-detected short GRBs is less than 1s.
Timing analysis can be a powerful tool for shading light on the still obscure emission physics and geometry of the prompt emission of gamma-ray bursts (GRBs). Fourier power density spectra (PDS) characterise time series as stochastic processes and can be used to search for coherent pulsations and, more in general, to investigate the dominant variability timescales in astrophysical sources. Because of the limited duration and of the statistical properties involved, modelling the PDS of individual GRBs is challenging, and only average PDS of large samples have been discussed in the literature thus far. We aim at characterising the individual PDS of GRBs to describe their variability in terms of a stochastic process, to explore their variety, and to carry out for the first time a systematic search for periodic signals and for a link between PDS properties and other GRB observables. We present a Bayesian procedure which uses a Markov chain Monte Carlo technique and apply it to study the individual power density spectra of 215 bright long GRBs detected with the Swift Burst Alert Telescope in the 15-150keV band from January 2005 to May 2015. The PDS are modelled with a power-law either with or without a break. Two classes of GRBs emerge: with or without a unique dominant time scale. A comparison with active galactic nuclei (AGNs) reveals similar distributions of PDS slopes. Unexpectedly, GRBs with subsecond dominant timescales and duration longer than a few ten seconds in the source frame appear to be either very rare or altogether absent. Three GRBs are found with possible evidence for periodic signal at 3.0-3.2{sigma} (Gaussian) significance, corresponding to a multi-trial chance probability of ~1%. Thus, we found no compelling evidence for periodic signal in GRBs. The analogy between the PDS of GRBs and of AGNs could tentatively hint at similar stochastic processes that rule BH accretion across different BH mass scales and objects. In addition, we find evidence that short dominant timescales and duration are not completely independent of each other, in contrast with commonly accepted paradigms.
Gamma-ray bursts (GRBs), which have been observed up to redshifts z~9.5, can be good probes of the early universe and have the potential to test cosmological models. Dainotti's analysis of GRB Swift afterglow light curves with known redshifts and a definite X-ray plateau shows an anti-correlation between the rest-frame time when the plateau ends (the plateau end time) and the calculated luminosity at that time (or approximately an anti-correlation between plateau duration and luminosity) (Dainotti+ 2008MNRAS.391L..79D, 2010ApJ...722L.215D). Here, we present an update of this correlation with a larger data sample of 101 GRBs with good light curves. Since some of this correlation could result from the redshift dependences of these intrinsic parameters, namely, their cosmological evolution, we use the Efron-Petrosian method to reveal the intrinsic nature of this correlation. We find that a substantial part of the correlation is intrinsic and describe how we recover it and how this can be used to constrain physical models of the plateau emission, the origin of which is still unknown. The present result could help to clarify the debated nature of the plateau emission.
The supermassive black holes at the center of active galactic nuclei (AGNs) are surrounded by obscuring matter that can block nuclear radiation. Depending on the amount of blocked radiation, the flux from the AGN can be too faint to be detected by currently flying hard X-ray (above 15keV) missions. At these energies only ~1% of the intensity of the cosmic X-ray background (CXB) can be resolved into point-like sources that are AGNs. In this work, we address the question of undetected sources contributing to the CXB with a very sensitive and new hard X-ray survey: the Swift-INTEGRAL X-ray (SIX) survey, which is obtained with the new approach of combining the Swift/BAT and INTEGRAL/IBIS X-ray observations. We merge the observations of both missions, which enhances the exposure time and reduces systematic uncertainties. As a result, we obtain a new survey over a wide sky area of 6200deg^2^ that is more sensitive than the surveys of Swift/BAT or INTEGRAL/IBIS alone. Our sample comprises 113 sources: 86 AGNs (Seyfert-like and blazars), 5 galaxies, 2 clusters of galaxies, 3 Galactic sources, 3 previously detected unidentified X-ray sources, and 14 unidentified sources. The scientific outcome from the study of the sample has been properly addressed to study the evolution of AGNs at redshift below 0.4.
The supermassive black holes at the center of active galactic nuclei (AGNs) are surrounded by obscuring matter that can block nuclear radiation. Depending on the amount of blocked radiation, the flux from the AGN can be too faint to be detected by currently operating hard X-ray (above 15 keV) missions. At these energies, only ~1% of the intensity of the cosmic X-ray background (CXB) can be resolved into point-like sources that are AGNs. In this work, the authors address the question of undetected sources contributing to the CXB with a very sensitive and new hard X-ray survey: the Swift-INTEGRAL X-ray (SIX) survey, which is obtained with the new approach of combining the Swift/BAT and INTEGRAL/IBIS X-ray observations. The authors merge the observations of both missions, which enhances the exposure time and reduces systematic uncertainties. As a result, they obtain a new survey over a wide sky area of 6200 deg<sup>2</sup> covering the region of the North Ecliptic Pole (NEP) and extending to the contiguous Coma region that is more sensitive than the surveys of Swift/BAT or INTEGRAL/IBIS alone. Their sample comprises 113 sources having S/N ratios of above 4.8 sigma: 86 AGNs (Seyfert-like and blazars), 5 galaxies, 2 clusters of galaxies, 3 Galactic sources, 3 previously detected unidentified X-ray sources, and 14 unidentified sources. The scientific outcome from the study of the sample has been properly addressed to study the evolution of AGNs at a redshift below 0.4. The authors do not find any evolution using the 1/V<sub>max</sub> method. Their sample of faint sources is a suitable target for the new generation of hard X-ray telescopes with focusing techniques. This table was created by the HEASARC in August 2012 based on an electronic version of Table 2 from the reference paper which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .
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