ASCA observations of deep ROSAT fields - V. The X-ray spectrum of hard X-ray selected QSOs

Pappa, A.; Stewart, G. C.; Georgantopoulos, I.; Griffiths, R. E.; Boyle, B.J.; Shanks, T.

doi:10.1046/j.1365-8711.2001.04725.x

Cited by 6 publications

(11 citation statements)

References 39 publications

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“…Indeed, while HR 1 is consistent with an unabsorbed Γ = 2 spectrum, at harder photon energies HR 2 calls for a much flatter X-ray spectrum, with Γ ∼ 1.6. A similar result has been recently found by Pappa et al (2001) by co-adding ROSAT and ASCA spectra of 21 BLAGN. Our result confirms that this is not due to a mismatch between ROSAT and ASCA calibrations and amphasizes the power of XMM-Newton in broad-band X-ray spectral studies.…”

Section: The Extragalactic X-ray Sourcessupporting

confidence: 89%

The XMM-Newton serendipitous survey

Barcons

Carrera

Watson

et al. 2002

A&A

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Abstract. We present the first results on the identifications of a medium sensitivity survey (X-ray flux limit 2 × 10 −14 erg cm −2 s −1 in the 0.5-4.5 keV band) at high galactic latitude (|b| > 20 • ) carried out with the XMM-Newton X-ray observatory within the AXIS observing programme. This study is being conducted as part of the XMMNewton Survey Science Centre activities towards the identification of the sources in the X-ray serendipitous sky survey. The sample contains 29 X-ray sources in a solid angle of 0.26 deg 2 (source density 113 ± 21 sources deg −2 ), out of which 27 (93%) have been identified. The majority of the sources are broad-line AGN (19), followed by narrow emission line X-ray emitting galaxies (6, all of which turn out to be AGN), 1 nearby non-emission line galaxy (NGC 4291) and 1 active coronal star. Among the identified sources we find 2 broad-absorption line QSOs (z ∼ 1.8 and z ∼ 1.9), which constitute ∼10% of the AGN population at this flux level, similar to optically selected samples. Identifications of a further 10 X-ray sources fainter than our survey limit are also presented.

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Section: The Extragalactic X-ray Sourcessupporting

confidence: 89%

The XMM-Newton serendipitous survey

Barcons

Carrera

Watson

et al. 2002

A&A

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“…Page (1998) also finds that the average ASCA spectrum of the soft X-ray selected QSOs from the RIXOS sample is steep (Γ ∼ 1.8). These results come in apparent contradiction to the findings of Pappa et al (2001) and Barcons et al (2002) who find spectral hardening in the average QSO spectrum. However, we note that our sample contains only soft X-ray selected QSOs in contrast to the surveys of Pappa et al (2001) and Barcons et al (2002).…”

Section: The Average Qso Spectrumcontrasting

confidence: 99%

“…They find an average spectrum of Γ ∼ 2.1−2.6 flattening with increasing redshift. Pappa et al (2001) studied the ROSAT/ASCA spectrum of 21 hard X-ray selected QSO. They find evidence for spectral curvature in the sense Send offprint requests to: I. Georgantopoulos, e-mail: ig@astro.noa.gr that the 2-10 keV ASCA spectrum has Γ ∼ 1.5 while their ROSAT spectrum is steep Γ ∼ 2.2.…”

Section: Introductionmentioning

confidence: 99%

On the XMM-Newton spectra of soft X-ray selected QSOs

Akylas

Georgantopoulos

Barcons

2003

A&A

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Abstract.We study the XMM-Newton spectra of a sample of 32 soft X-ray selected QSOs. Our goal is to check, using the spectra of moderate redshift (z ∼ 1.5), faint ( f 0.2−8 keV > 5 × 10 −15 erg cm −2 s −1 ) broad-line QSOs, previous claims for either significant intrinsic absorption or spectral hardening at high energies. We derive hardness ratios for all sources and furthermore we perform spectral fits for the 11 brighter sources. The majority of sources have steep spectra Γ > 1.9. We find a few QSOs with large amounts of intrinsic absorption, as high as N H ∼ 10 23 cm −2 . We find no strong evidence for spectral hardening above 2 keV. The coadded QSO spectrum is well described by a single power-law with photon index of ∼1.9, demonstrating that, on average, any effects of absorption are not important. This suggests that the discrepancy between the X-ray background and the (soft X-ray selected) QSO spectrum holds well at the faint fluxes probed here.

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“…The data clearly suggest these sources are radio galaxies. The cross identification with the NED catalogue (Voges et al 1999;Condon et al 1982;Pappa et al 2001) also confirms their double-source morphology and classifies them as radio galaxies. Hence, these three sources are extragalactic radio sources.…”

Section: Extragalactic Radio Sourcessupporting

confidence: 61%

GMRT observations of the field of INTEGRAL X-ray sources. II

Pandey¹,

Rao²,

Manchanda³

et al. 2006

A&A

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We conducted low-frequency radio observations with the Giant Metrewave Radio Telescope (GMRT) of the 40 new hard X-ray sources discovered by the INTEGRAL satellite. This survey was conducted in order to study radio emissions from these sources, to provide precise position, and to identify new microquasar candidates. Our observations show that 24 of the X-ray sources have radio candidates within the INTEGRAL error circle. Based on the radio morphology, variability, and information available from different wavelengths, we categorize them as seventeen Galactic sources (4 unresolved, 7 extended, 6 extended sources in diffuse regions) and seven extragalactic sources (2 unresolved, 5 extended). A detailed account of seventeen of these sources was presented in an earlier paper. Based on the radio data for the remaining sources at 0.61 GHz and on the available information from NVSS, DSS, 2MASS, and NED, we have identified possible radio counterparts for the hard X-ray sources. The three unresolved sources, i.e., IGR J17303−0601, IGR J17464−3213, and IGR J18406−0539, are discussed in detail. These sources have been associated with compact sources that are variable in radio and X-rays. The remaining fourteen sources have an extended radio morphology and either are diffuse Galactic regions or have an extragalactic origin.

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ASCA observations of deep ROSAT fields - V. The X-ray spectrum of hard X-ray selected QSOs

Cited by 6 publications

References 39 publications

The XMM-Newton serendipitous survey

The XMM-Newton serendipitous survey

On the XMM-Newton spectra of soft X-ray selected QSOs

GMRT observations of the field of INTEGRAL X-ray sources. II

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