A Minisurvey of X‐Ray Point Sources in Starburst and Nonstarburst Galaxies

Kilgard, R. E.; Kaaret, Philip; Krauss, M. I.; Prestwich, Andrea; Raley, Michael; Zezas, A.

doi:10.1086/340490

Cited by 108 publications

(170 citation statements)

References 22 publications

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“…2 & 3 entitled "Freely Fit"). The slopes of the disc CLFs above L b are between the values expected for starburst galaxies and for spiral galaxies from Kilgard et al (2002). Given that we are examining the disc of a spiral galaxy, this is to be expected.…”

Section: Luminosity Functionsmentioning

confidence: 66%

An X-ray spectral survey of the disc of M 31 with XMM-Newton

Greening¹,

Barnard²,

Kolb³

et al. 2009

A&A

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Aims. We present the results of a complete spectral survey of the X-ray point sources detected in five XMM-Newton observations along the major axis of M 31 but avoiding the central bulge, aimed at establishing the population characteristics of X-ray sources in this galaxy. Methods. We obtained background subtracted spectra and lightcurves for each of the 335 X-ray point sources detected across the five observations from 2002. We also correlate our source list with those of earlier X-ray surveys and radio, optical and infra-red catalogues. Sources with more than 50 source counts are individually spectrally fit in order to create the most accurate luminosity functions of M 31 to date. Results. Based on the spectral fitting of these sources with a power law model, we observe a broad range of best fit photon index. From this distribution of best fit index, we identify 16 strong high mass X-ray binary system candidates in M 31. We show the first cumulative luminosity functions created using the best fit spectral model to each source with more than 50 source counts in the disc of M 31. The cumulative luminosity functions show a distinct flattening in the X-ray luminosity L X interval 37.0 log L X erg s −1 37.5. Such a feature may also be present in the X-ray populations of several other galaxies, but at a much lower statistical significance. We investigate the number of AGN present in our source list and find that above L X ∼ 1.4 × 10 36 erg s −1 the observed population is statistically dominated by the point source population of M 31.

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Section: Luminosity Functionsmentioning

confidence: 66%

An X-ray spectral survey of the disc of M 31 with XMM-Newton

Greening¹,

Barnard²,

Kolb³

et al. 2009

A&A

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show abstract

“…This slope is between the values found in disk galaxies (1.1-1.4) and active star-forming galaxies (0.5-0.8 for M82, NGC 253, and the Antennae) and significantly lower than those derived for ellipticals and lenticulars (Kilgard et al 2002 and references therein). A break in the luminosity function (i.e., a change in its slope) can potentially be used to measure the formation history and age of the X-ray source population (Kilgard et al 2002;Wu et al 2003) and the amount of beaming in luminous sources (Körding et al 2002). Such a break is not apparent in the luminosity function of NGC 5194.…”

Section: Incidence Of Ultraluminous X-ray Sources and Luminosity Funcmentioning

confidence: 99%

“…One pertinent finding is that starburst galaxies often contain ULXs (e.g., Kilgard et al 2002 for a minisurvey; for M82 see Matsumoto et al 2001, Kaaret et al 2001, and Griffiths et al 2000; for the Antennae [NGC 4038/39], see Fabbiano, Zezas, & Murray 2001; for the Circinus galaxy see Bauer et al 2001 andSmith &; for NGC 3256 see Lira et al 2002; and for NGC 3628 see Strickland et al 2001). This finding strongly suggests that many ULXs are associated with ongoing star formation and perhaps with massive stars.…”

Section: Introductionmentioning

confidence: 99%

The Luminous X‐Ray Source Population in M51 Observed withChandra

Terashima

Wilson

2004

ApJ

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We present the results of two Chandra observations (separated by 1 yr) of the population of X-ray sources in the spiral galaxy M51 (NGC 5194 and NGC 5195). One hundred and thirteen X-ray sources have been detected in an 8A4 Â 8A4 (20:4 Â 20:4 kpc) region, and 84 and 12 of them project within the disks of NGC 5194 and NGC 5195, respectively. Nine and 28 sources have luminosities exceeding 1 Â 10 39 ergs s À1 (ultraluminous X-ray sources or ULXs) and 1 Â 10 38 ergs s À1 in the 0.5-8 keV band, respectively, assuming that they are associated with M51. The number of ULXs is much higher than found in most normal spiral and elliptical galaxies. Most of the X-ray sources and all seven of the ULXs in NGC 5194 are located in, or close to, a spiral arm, suggesting a connection with recent star formation. The cumulative luminosity function of the X-ray sources in NGC 5194 with Lð0:5 8 keVÞ > 10 38 ergs s À1 is well described by a power law, N ½>L(0.5-8 keVÞ / L(0.5-8 keV) À with ¼ 0:91. The X-ray spectra of most of the detected sources are consistent with a power law with a photon index between 1 and 2, with a few sources showing harder or softer spectra. The spectra of most ULXs are consistent with both a power law and a multicolor disk blackbody (MCD) model, while a power-law model is preferable to an MCD model in two ULXs. One ULX (NGC 5194 source 69) shows drastic spectral steepening accompanied by a decline in luminosity by a factor of 3460 in the 2-10 keV band between the two observations. This source also exhibited a possible period of 2.1 hr in the 2000 observation. Another ULX (NGC 5194 source 26) shows strong emission lines from highly ionized species. The masses of the compact objects and mass accretion rates in ULXs and other X-ray sources are not well constrained by these observations. If we adopt an MCD interpretation, their MCD parameters imply that most of the X-ray sources are stellar mass ($5-10 M ) black holes accreting near or above the Eddington rate, although other possibilities (intermediate-mass black holes and relativistically beamed emission) cannot be excluded. The power-law sources may instead represent Comptonized disk or nonthermal emission. Two ULXs have very soft spectra; MCD models require kT % 0:1 keV. We discuss the possibility that this soft emission originates in an accretion disk around an intermediate-mass black hole. We also present a study of the nucleus of, and discrete sources (including two ULXs) in, the companion galaxy NGC 5195.

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“…More recently, comparisons of XLFs have suggested a dependence of the normalization on the star formation rate (SRF) of the galaxy (Kilgard et al 2002;Grimm et al 2003). Grimm et al (2003), in particular, propose that all HMXB XLFs follow a similar cumulative slope of -0.6, and have normalization strictly proportional to the SFR.…”

Section: X-ray Luminosity Functionsmentioning

confidence: 99%

Joint Discussion 6 Neutron stars and black holes in star clusters

et al. 2006

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This article was co-authored by all invited speakers at Joint Discussion 6 onNeutron Stars and Black Holes in Star Clusters, which took place during the IAU General Assembly in Prague, Czech Republic, on August 17 and 18, 2006. Each section presents a short summary of recent developments in a key area of research, incorporating the main ideas expressed during the corresponding panel discussion at the meeting.

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A Minisurvey of X‐Ray Point Sources in Starburst and Nonstarburst Galaxies

Cited by 108 publications

References 22 publications

An X-ray spectral survey of the disc of M 31 with XMM-Newton

An X-ray spectral survey of the disc of M 31 with XMM-Newton

The Luminous X‐Ray Source Population in M51 Observed withChandra

Joint Discussion 6 Neutron stars and black holes in star clusters

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