Number of results to display per page
Search Results
- ID:
- ivo://nasa.heasarc/swiftgrb
- Title:
- Swift Gamma Ray Bursts Catalog
- Short Name:
- SWIFTGRB
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- 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 .
- ID:
- ivo://nasa.heasarc/swiftguano
- Title:
- Swift Gamma-ray Urgent Archiver for Novel Opportunities (GUANO) Events
- Short Name:
- SWIFTGUANO
- Date:
- 27 Sep 2024
- 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 .
- ID:
- ivo://CDS.VizieR/J/ApJS/209/20
- Title:
- Swift GRB catalog with X-ray data
- Short Name:
- J/ApJS/209/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/589/A98
- Title:
- Swift GRBs individual power density spectra
- Short Name:
- J/A+A/589/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/774/157
- Title:
- Swift GRBs with X-ray afterglows and z<9.5
- Short Name:
- J/ApJ/774/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/34
- Title:
- Swift-INTEGRAL X-ray (SIX) survey
- Short Name:
- J/ApJS/201/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://nasa.heasarc/sixsrvycat
- Title:
- Swift-INTEGRAL X-Ray (SIX) Survey Catalog
- Short Name:
- SIXSRVYCAT
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- 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 .
21209. Swift J1745-26 polarized jet
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/3265
- Title:
- Swift J1745-26 polarized jet
- Short Name:
- J/MNRAS/437/3265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Swift J1745-26 is an X-ray binary towards the Galactic Centre that was detected when it went into outburst in 2012 September. This source is thought to be one of a growing number of sources that display `failed outbursts', in which the self-absorbed radio jets of the transient source are never fully quenched and the thermal emission from the geometrically thin inner accretion disc never fully dominates the X-ray flux. We present multifrequency data from the Very Large Array, Australia Telescope Compact Array and Karoo Array Telescope (KAT-7) radio arrays, spanning the entire period of the outburst. Our rich data set exposes radio emission that displays a high level of large-scale variability compared to the X-ray emission and deviations from the standard radio-X-ray correlation that are indicative of an unstable jet and confirm the outburst's transition from the canonical hard state to an intermediate state. We also observe steepening of the spectral index and an increase of the linear polarization to a large fraction (~50%) of the total flux, as well as a rotation of the electric vector position angle. These are consistent with a transformation from a self-absorbed compact jet to optically thin ejecta - the first time such a discrete ejection has been observed in a failed outburst - and may imply a complex magnetic field geometry.
21210. Swift long gamma-ray bursts
- ID:
- ivo://CDS.VizieR/J/ApJS/248/21
- Title:
- Swift long gamma-ray bursts
- Short Name:
- J/ApJS/248/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The exact relationship between the long gamma-ray burst (LGRB) rate and the cosmic star formation rate (CSFR) is essential for using LGRBs as cosmological probes. In this work, we collect a large sample composed of 371 Swift LGRBs with known redshifts and prompt emission properties. We first compare the rest-frame prompt properties of these bursts in different redshift bins, finding negligible redshift evolution of the luminosity of LGRBs with L_iso_>~10^51^erg/s between z~1 and z~4. Then, by utilizing the CSFR obtained from the large-scale cosmological hydrodynamical simulation, the Illustris simulation, we calculate the cumulative redshift distribution of LGRBs under different metallicity thresholds. After comparing with our sample, we find that the predictions with a moderate threshold between 0.3Z_{sun}_<=Z_th_<=1.0Z_{sun}_ are consistent with the sample between redshift 0<z<3, while at higher redshifts, between 3<z<5, all metallicity thresholds fit the data well. When changing to an empirical model based on observations, the predictions show similar results as well. After comparing with the metallicity distribution of the observed LGRB host galaxies between 0<z<1, we confirm that the production of LGRBs in galaxies with super-solar metallicity is suppressed. Nevertheless, considering that a significant fraction of stars are born in sub-solar metallicity environments at z>~3, we suggest that, as a first approximation, LGRBs can be used as direct tracers of the CSFR in this redshift range.