- ID:
- ivo://CDS.VizieR/J/ApJ/749/21
- Title:
- AGNs detected by 60 month Swift/BAT survey
- Short Name:
- J/ApJ/749/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of ~2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent ~5% of AGN samples detected above 15keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to ~10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9^+4.1^_-2.9_x10^-5^/Mpc3 for objects with a de-absorbed luminosity larger than 2x10^42^erg/s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (<=85Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.
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- ID:
- ivo://CDS.VizieR/J/ApJ/678/102
- Title:
- BAT X-ray survey. I.
- Short Name:
- J/ApJ/678/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We applied the maximum likelihood (ML) method, as an image reconstruction algorithm, to the BAT (Burst Alert Telescope) X-Ray Survey (BXS). This method was specifically designed to preserve the full statistical information in the data and to avoid mosaicking of many exposures with different pointing directions, thus reducing systematic errors when co-adding images. We reconstructed, in the 14-170keV energy band, the image of a 90x90deg^2^ sky region, centered on (RA, DE)=(105{deg}, -25{deg}), which BAT surveyed with an exposure time of ~1Ms (in 2005 November). The best sensitivity in our image is ~0.85mCrab or 2.0x10^-11^ergs/cm^2^. We detect 49 hard X-ray sources above the 4.5{sigma} level; of these, only 12 were previously known as hard X-ray sources (>15keV). Swift XRT observations allowed us to firmly identify the counterparts for 15 objects, while 2 objects have Einstein IPC counterparts (Harris et al., 1990, in Imaging X-Ray Astronomy. A Decade of Achievements, ed. M. Elvis (Cambridge: Cambridge Univ. Press), 309); in addition to those, we found a likely counterpart for 13 objects by correlating our sample with the ROSAT All-Sky Survey Bright Source Catalog (Voges et al., 1999, Cat. <IX/10>). Seven objects remain unidentified.
- ID:
- ivo://CDS.VizieR/J/ApJS/207/19
- Title:
- Hard X-ray survey from Swift-BAT 2004-2010
- Short Name:
- J/ApJS/207/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of sources detected in 70 months of observations with the Burst Alert Telescope (BAT) hard X-ray detector on the Swift gamma-ray burst observatory. The Swift-BAT 70 month survey has detected 1171 hard X-ray sources (more than twice as many sources as the previous 22 month survey) in the 14-195 keV band down to a significance level of 4.8{sigma}, associated with 1210 counterparts. The 70 month Swift-BAT survey is the most sensitive and uniform hard X-ray all-sky survey and reaches a flux level of 1.03x10^-11^erg/s/cm2 over 50% of the sky and 1.34x10^-11^erg/s/cm2 over 90% of the sky. The majority of new sources in the 70 month survey continue to be active galactic nuclei, with over 700 in the catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A48
- Title:
- Palermo Swift-BAT Hard X-ray Catalogue
- Short Name:
- J/A+A/510/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Palermo Swift-BAT hard X-ray catalogue obtained from the analysis of the the data relative to the first 39 months of the Swift mission. We have developed a dedicated software to perform data reduction, mosaicking and source detection on the BAT survey data. We analyzed the BAT dataset in three energy bands (14-150keV, 14-30keV, 14-70keV), obtaining a list of 962 detections above a significance threshold of 4.8 standard deviations. The identification of the source counterparts was pursued using three strategies: cross-correlation with published hard X-ray catalogues, analysis of field observations of soft X-ray instruments, cross-correlation with the SIMBAD database. The survey covers 90% of the sky down to a flux limit of 2.5x10^-11^erg/cm^2^/s and 50% of the sky down to a flux limit of 1.8x10^-11^erg/cm^2^/s in the 14-150keV band. We derived a catalogue of 754 identified sources, of which ~69% are extragalactic, ~27% are Galactic objects, ~4% are already known X-ray or gamma ray emitters whose nature has not been determined yet. The integrated flux of the extragalactic sample is ~1% of the Cosmic X-ray background in the 14-150keV range.
- ID:
- ivo://CDS.VizieR/J/A+A/528/A122
- Title:
- SwiftFT catalog
- Short Name:
- J/A+A/528/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/524/A64
- Title:
- The 54-month Palermo BAT-survey catalogue
- Short Name:
- J/A+A/524/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Second Palermo Swift-BAT hard X-ray catalogue obtained by analysing data acquired in the first 54 months of the Swift mission. Using our software dedicated to the analysis of data from coded mask telescopes, we analysed the BAT survey data in three energy bands (15-30keV, 15-70keV, 15-150keV), obtaining a list of 1256 detections above a significance threshold of 4.8 standard deviations. The identification of the source counterparts is pursued using two strategies: the analysis of field observations of soft X-ray instruments and cross-correlation of our catalogue with source databases. The survey covers 50% of the sky to a 15-150keV flux limit of 1.0x10^-11^erg/cm2/s and 9.2x10^-12^erg/cm2/s for |b|<10 and |b|>10, respectively. The Second Palermo Swift-BAT hard X-ray catalogue includes 1079 (~86%) hard X-ray sources with an associated counterpart (26 with a double association and 2 with a triple association) and 177 BAT excesses (~14%) that still lack a counterpart. The distribution of the BAT sources among the different object classes consists of ~19% Galactic sources, ~57% extragalactic sources, and ~10% sources with a counterpart at softer energies whose nature has not yet been determined. About half of the BAT associated sources lack a counterpart in the ROSAT catalogues. This suggests that either moderate or strong absorption may be preventing their detection in the ROSAT energy band. The comparison of our BAT catalogue with the Fermi Large Area Telescope First Source Catalogue identifies 59 BAT/Fermi correspondences: 48 blazars, 3 Seyfert galaxies, 1 interacting galaxy, 3 high mass X-ray binaries, and 4 pulsars/supernova remnants. This small number of correspondences indicates that different populations make the sky shine in these two different energy bands.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/4
- Title:
- The 105-month Swift-BAT all-sky hard X-ray survey
- Short Name:
- J/ApJS/235/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of hard X-ray sources detected in the first 105-months of observations with the Burst Alert Telescope (BAT) coded-mask imager on board the Swift observatory. The 105-month Swift-BAT survey is a uniform hard X-ray all-sky survey with a sensitivity of 8.40x10^-12^erg/s/cm^2^ over 90% of the sky and 7.24x10^-12^erg/s/cm^2^ over 50% of the sky in the 14-195keV band. The Swift-BAT 105-month catalog provides 1632 (422 new detections) hard X-ray sources in the 14-195 keV band above the 4.8{sigma} significance level. Adding to the previously known hard X-ray sources, 34% (144/422) of the new detections are identified as Seyfert active galactic nuclei (AGNs) in nearby galaxies (z<0.2). The majority of the remaining identified sources are X-ray binaries (7%, 31) and blazars/BL Lac objects (10%, 43). As part of this new edition of the Swift-BAT catalog, we release eight-channel spectra and monthly sampled light curves for each object in the online journal and at the Swift-BAT 105-month website.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/14
- Title:
- The Swift/BAT hard X-ray transient monitor
- Short Name:
- J/ApJS/209/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for a full-day observation and a time resolution as fine as 64s. The three main purposes of the monitor are (1) the discovery of new transient X-ray sources, (2) the detection of outbursts or other changes in the flux of known X-ray sources, and (3) the generation of light curves of more than 900 sources spanning over eight years. The primary interface for the BAT transient monitor is a public Web site. Between 2005 February 12 and 2013 April 30, 245 sources have been detected in the monitor, 146 of them persistent and 99 detected only in outburst. Among these sources, 17 were previously unknown and were discovered in the transient monitor. In this paper, we discuss the methodology and the data processing and filtering for the BAT transient monitor and review its sensitivity and exposure. We provide a summary of the source detections and classify them according to the variability of their light curves. Finally, we review all new BAT monitor discoveries. For the new sources that are previously unpublished, we present basic data analysis and interpretations.
