The HEAO A-1 X-ray source catalog

Wood, Kenneth; Meekins, J. F.; Yentis, D.; Smathers, H. W.; McNutt, D. P.; Bleach, R. D.; Friedman, H.; Byram, E. T.; Chubb, T. A.; Meidav, Meir

doi:10.1086/190992

Cited by 224 publications

(175 citation statements)

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“…In the last decade, the advent of the ASCA and Beppo-SAX satellites has allowed for the first time the detection and identification of AGNs as the main counterparts of hard (2-10 keV) X-ray sources down to fluxes of $5 Â 10 À14 ergs cm À2 s À1 , more than 2 orders of magnitude fainter than HEAO 1 detections (Wood et al 1984). These identifications accounted for about 30% of the 2-10 keV hard X-ray background (Ueda et al 1998;Fiore et al 1999).…”

Section: Introductionmentioning

confidence: 99%

TheBeppoSAXHigh‐Energy Large‐Area Survey. V. The Nature of the Hard X‐Ray Source Population and Its Evolution

Franca

Fiore

Vignali

et al. 2002

ApJ

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We present optical spectroscopic identifications of hard X-ray (5-10 keV) selected sources belonging to the High-Energy Large-Area Survey sample obtained with BeppoSAX down to a 5-10 keV flux limit of f 5 10 keV $ 3 Â 10 À14 ergs cm À2 s À1 . The sample consists of 118 sources. There are 25 sources that have been identified through correlations with catalogs of known sources. A spectroscopic identification for 49 more has been searched for with the telescope. The results of 13 fields were empty down to R ¼ 21. There were 37 sources identified as type 1 active galactic nuclei (AGNs) and nine as type 2 AGNs. The remaining sources are five narrow emission-line galaxies, six clusters, two BL Lac objects, one radio galaxy, and one star. Combining these objects with other hard X-ray selected AGNs from ASCA and HEAO 1, we find that the local luminosity function of type 1 AGNs (AGN 1s) in the 2-10 keV band is fairly well represented by a double power law function. There is evidence for significant cosmological evolution according to a pure luminosity evolution (PLE) model [L X ðzÞ / ð1 þ zÞ k ], with k ¼ 2:12 and 2.22 ( k ' 0:14) in a ð m ; Þ ¼ ð1:0; 0:0Þ and a ð m ; Þ ¼ ð0:3; 0:7Þ cosmology, respectively. The data show an excess of faint high-redshift type AGN 1s, which is well modeled by a luminosity-dependent density evolution (LDDE), similar to what is observed in soft X-rays. However, in both cosmologies, the statistics are not significant enough to distinguish between the PLE and LDDE models. The fitted models imply a contribution of AGN 1s to the 2-10 keV X-ray background from 35% up to 60%.

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Section: Introductionmentioning

confidence: 99%

TheBeppoSAXHigh‐Energy Large‐Area Survey. V. The Nature of the Hard X‐Ray Source Population and Its Evolution

Franca

Fiore

Vignali

et al. 2002

ApJ

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“…In the hard 2-10 keV band the limiting sensitivity for source detection is approximately 3 × 10 −12 erg cm −2 s −1 . This is roughly an order of magnitude deeper than the all-sky surveys which are currently available in this energy range, such as those from Uhuru, Ariel V, and HEAO-1 (Forman et al 1978;McHardy et al 1981;Piccinotti et al 1982;Wood et al 1984). The situation is, of course, very different if one considers surveys with sky-coverage much less than 4π steradians.…”

Section: Introductionmentioning

confidence: 93%

TheXMM-Newtonslew survey in the 2–10 keV band

Warwick

Saxton

Read

2012

A&A

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Context. The on-going XMM-Newton Slew Survey (XSS) provides coverage of a significant fraction of the sky in a broad X-ray bandpass. Although shallow by contemporary standards, in the "classical" 2-10 keV band of X-ray astronomy, the XSS provides significantly better sensitivity than any currently available all-sky survey. Aims. We investigate the source content of the XSS, focussing on detections in the hard 2-10 keV band down to a very low threshold (≥4 counts net of background). At the faint end, the survey reaches a flux sensitivity of roughly 3 × 10 −12 erg cm −2 s −1 (2-10 keV). Methods. Our starting point was a sample of 487 sources detected in the XSS (up to and including release XMMSL1d2) at high galactic latitude in the hard band. Through cross-correlation with published source catalogues from surveys spanning the electromagnetic spectrum from radio through to gamma-rays, we find that 45% of the sources have likely identifications with normal/active galaxies. A further 18% are associated with other classes of X-ray object (nearby coronally active stars, accreting binaries, clusters of galaxies), leaving 37% of the XSS sources with no current identification. We go on to define an XSS extragalactic sample comprised of 219 galaxies and active galaxies selected in the XSS hard band. We investigate the properties of this extragalactic sample including its X-ray log N − log S distribution. Results. We find that in the low-count limit, the XSS is, as expected, strongly affected by Eddington bias. There is also a very strong bias in the XSS against the detection of extended sources, most notably clusters of galaxies. A significant fraction of the detections at and around the low-count limit may be spurious. Nevertheless, it is possible to use the XSS to extract a reasonably robust sample of extragalactic sources, excluding galaxy clusters. The differential log N − log S relation of these extragalactic sources matches very well to the HEAO-1 A2 all-sky survey measurements at bright fluxes and to the 2XMM source counts at the faint end. Conclusions. The substantial sky coverage afforded by the XSS makes this survey a valuable resource for studying X-ray bright source samples, including those selected specifically in the hard 2-10 keV band.

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“…At X-ray energies, H 2356-309 was initially detected by the UHURU satellite (Forman et al 1978) and later by the HEAO-I satellite (Wood et al 1984). It is among the X-ray brightest of the 150 high-frequency peaked BL Lac objects (HBL) in the Sedentary Survey (Giommi et al 2005), which contains HBLs characterized by their exceptionally high X-ray-to-radio flux ratio.…”

Section: Introductionmentioning

confidence: 99%

Multi-wavelength observations of H 2356–309

Abramowski¹,

Acero²,

Aharonian³

et al. 2010

A&A

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Aims. The properties of the broad-band emission from the high-frequency peaked BL Lac H 2356-309 (z = 0.165) are investigated. Methods. Very high energy (VHE; E > 100 GeV) observations of H 2356-309 were performed with the High Energy Stereoscopic System ( Results. A strong VHE signal, ∼13σ total, was detected by HESS after the four years HESS observations (116.8 h live time). The integral flux above 240 GeV is I(>240 GeV) = (3.06 ± 0.26 stat ± 0.61 syst ) × 10 −12 cm −2 s −1 , corresponding to ∼1.6% of the flux observed from the Crab Nebula. A time-averaged energy spectrum is measured from 200 GeV to 2 TeV and is characterized by a power law (photon index of Γ = 3.06 ± 0.15 stat ± 0.10 syst ). Significant small-amplitude variations in the VHE flux from H 2356-309 are seen on time scales of months and years, but not on shorter time scales. No evidence for any variations in the VHE spectral slope are found within these data. The XMM-Newton X-ray measurements show a historically low X-ray state, characterized by a hard, broken-power-law spectrum on both nights. Conclusions. The broad-band spectral energy distribution (SED) of the blazar can be adequately fit using a simple one-zone synchrotron selfCompton (SSC) model. In the SSC scenario, higher VHE fluxes could be expected in the future since the observed X-ray flux is at a historically low level.

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The HEAO A-1 X-ray source catalog

Cited by 224 publications

References 0 publications

TheBeppoSAXHigh‐Energy Large‐Area Survey. V. The Nature of the Hard X‐Ray Source Population and Its Evolution

TheBeppoSAXHigh‐Energy Large‐Area Survey. V. The Nature of the Hard X‐Ray Source Population and Its Evolution

TheXMM-Newtonslew survey in the 2–10 keV band

Multi-wavelength observations of H 2356–309

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