The Palermo<i>Swift</i>-BAT hard X-ray catalogue

Cusumano, G.; Parola, V. La; Segreto, A.; Mangano, V.; Ferrigno, C.; Maselli, A.; Romano, P.; Mineo, T.; Sbarufatti, B.; Campana, S.; Chincarini, G.; Giommi, P.; Masetti, N.; Moretti, A.; Tagliaferri, G.

doi:10.1051/0004-6361/200811184

Cited by 91 publications

(98 citation statements)

References 42 publications

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“…X-ray observations X-ray photometric observations exist for all sources in the local AGN sample. For one source (NGC 1125) only Swift-BAT observations are available at very high energies (>15 keV; Cusumano et al 2010), and no X-ray spectrum can be derived. For another source (IRAS 08572+3915) there are Chandra observations available (Iwasawa et al 2009), but unfortunately they are not sensitive enough to allow the derivation of the X-ray column through X-ray spectroscopy.…”

Section: Discussionmentioning

confidence: 99%

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

Georgantopoulos

Dasyra²,

Rovilos³

et al. 2011

A&A

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Observations with the IRS spectrograph onboard Spitzer have found many sources with very deep Si features at 9.7 μm, that have optical depths of τ > 1. Since it is believed that a few of these systems in the local Universe are associated with Compton-thick active galactic nuclei (hereafter AGN), we set out to investigate whether the presence of a strong Si absorption feature is a good indicator of a heavily obscured AGN. We compile X-ray spectroscopic observations available in the literature on the optically-thick (τ 9.7 μm > 1) sources from the 12 μm IRAS Seyfert sample. We find that the majority of the high-τ optically confirmed Seyferts (six out of nine) in the 12 μm sample are probably Compton-thick. Thus, we provide direct evidence of a connection between mid-IR optically-thick galaxies and Compton-thick AGN, with the success rate being close to 70% in the local Universe. This is at least comparable to, if not better than, other rates obtained with photometric information in the mid to far-IR, or even mid-IR to X-rays. However, this technique cannot provide complete Compton-thick AGN samples, i.e., there are many Compton-thick AGN that do not display significant Si absorption, with the most notable example being NGC 1068. After assessing the validity of the high 9.7 μm optical-depth technique in the local Universe, we attempt to construct a sample of candidate Compton-thick AGN at higher redshifts. We compile a sample of seven high-τ Spitzer sources in the Great Observatories Origins Deep Survey (GOODS) and five in the Spitzer First-Look Survey. All these have been selected to have no PAH features (EW 6.2 μm < 0.3 μm) to maximise the probability that they are bona-fide AGN. Six out of the seven GOODS sources have been detected in X-rays, while for the five FLS sources only X-ray flux upper limits are available. The high X-ray luminosities (L X > 10 42 erg s −1 ) of the detected GOODS sources corroborates that these are AGN. For FLS, ancillary optical spectroscopy reveals hidden nuclei in two more sources. SED fitting can support the presence of an AGN in the vast majority of sources. Owing to the limited photon statistics, we cannot derive useful constraints from X-ray spectroscopy on whether these sources are Compton-thick. However, the low L X /L 6 μm luminosity ratios, suggest that at least four out of the six detected sources in GOODS may be associated with Compton-thick AGN.

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Section: Discussionmentioning

confidence: 99%

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

Georgantopoulos

Dasyra²,

Rovilos³

et al. 2011

A&A

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“…The X-ray luminosities listed in this table for the various objects were computed using the fluxes reported in Table 1). Voges et al (1999Voges et al ( , 2000, Bird et al (2010), Cusumano et al (2010), Krivonos et al (2010), and Landi et al (2010).…”

Section: Cvsmentioning

confidence: 99%

“…In these tables, X-ray luminosities were computed from the fluxes reported in Voges et al (1999Voges et al ( , 2000, Saxton et al (2008), Krivonos et al (2009, Cusumano et al (2010), Krivonos et al (2010), Landi et al (2010), Rodriguez et al (2010), and Tueller et al (2010).…”

Section: Agnsmentioning

confidence: 99%

“…These differences between the IBIS and BAT surveys can be attributed to different (and, to some extent, complementary) spacecraft observational strategies, INTEGRAL being mainly dedicated to Galactic plane scans and Swift covering more of the ecliptic pole regions and the sky outside the Galactic plane (see Bird et al 2010;Cusumano et al 2010;and Tueller et al 2010, for details).…”

Section: Statistical Considerationsmentioning

confidence: 99%

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Unveiling the nature ofINTEGRALobjects through optical spectroscopy

Masetti¹,

Parisi

Palazzi³

et al. 2010

A&A

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Hard X-ray surveys performed by the INTEGRAL satellite have discovered a conspicuous fraction (up to 30%) of unidentified objects among the detected sources. Here we continue our program of identification of these objects by (i) selecting probable optical candidates by means of positional cross-correlation of the INTEGRAL detections with soft X-ray, radio, and/or optical archives and (ii) performing optical spectroscopy on them. As a result, we pinpointed and identified, or more accurately characterized, 44 definite or likely counterparts of INTEGRAL sources. Among them, 32 are active galactic nuclei (AGNs; 18 with broad emission lines, 13 with narrow emission lines only, and one X-ray bright, optically normal galaxy) with redshift 0.019 < z < 0.6058, 6 cataclysmic variables (CVs), 5 high-mass X-ray binaries (2 of which in the Small Magellanic Cloud), and 1 low-mass X-ray binary. This was achieved by using 7 telescopes of various sizes and archival data from two online spectroscopic surveys. The main physical parameters of these hard X-ray sources were also determined using the multiwavelength information available in the literature. In general, AGNs are the most abundant population among hard X-ray objects, and our results confirm the tendency of finding AGNs more frequently than any other type of hard X-ray emitting object among unidentified INTEGRAL sources when optical spectroscopy is used as an identification tool. Moreover, the deeper sensitivity of the more recent INTEGRAL surveys enables one to begin detecting hard X-ray emission above 20 keV from sources such as LINER-type AGNs and non-magnetic CVs.

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“…The analysis of progressively longer periods provided with BAT survey data has produced in recent years catalogues and lists of Galactic and extragalactic sources (Markwardt et al 2005;Ajello et al 2008;Tueller et al 2008;Ajello et al 2009b;Tueller et al 2010). The largest (to date) hard X-ray catalogue, obtained from the reduction of 39 months of BAT survey data accumulated since its A&A 520, A47 (2010) launch, is the First Palermo BAT Catalogue (hereafter PBC39, Cusumano et al 2010). It includes 754 identified objects of galactic and extragalactic nature detected with a high statistical significance; among extragalactic sources, 71 were classified as blazars.…”

Section: Introductionmentioning

confidence: 99%

The blazar content in theSwift-BAT hard X-ray sky

Maselli

Cusumano

Massaro

et al. 2010

A&A

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Aims. We present the results from a study of the blazar content in the 15-150 keV map of the entire sky obtained analysing 39 months of data collected by the BAT telescope aboard the Swift satellite. Methods. We performed a cross-correlation of the significance map, obtained with a dedicated highly efficient algorithm for data processing and image reconstruction of the BAT survey data, with the blazar population of the Roma-BZCAT. After corrections for source confusion and spurious detections, we found significance excesses higher than two standard deviations for 304 sources, and the corresponding fraction of expected spurious associations is ∼20%. We selected hard X-ray blazars according to their significance level and carried out a statistical analysis to characterise their emission properties. Results. A sample of 121 blazars detected at a significance level σ > 3 is discussed in greater detail. The fraction of blazars with uncertain classification in this sample is considerable (∼23%), more than twice the percentage obtained considering all the blazars classified in the Roma-BZCAT (∼9%). We attribute the X-ray flux of the majority of selected BL Lac objects to the synchrotron emission.

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The PalermoSwift-BAT hard X-ray catalogue

Cited by 91 publications

References 42 publications

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

Unveiling the nature ofINTEGRALobjects through optical spectroscopy

The blazar content in theSwift-BAT hard X-ray sky

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The PalermoSwift-BAT hard X-ray catalogue

Cited by 91 publications

References 42 publications

X-ray observations of highly obscuredτ9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

X-ray observations of highly obscuredτ9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

Unveiling the nature ofINTEGRALobjects through optical spectroscopy

The blazar content in theSwift-BAT hard X-ray sky

Contact Info

Product

Resources

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X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?