Old and Young X‐Ray Point Source Populations in Nearby Galaxies

Colbert, E. J. M.; Heckman, Timothy M.; Ptak, Andrew; Strickland, David; Weaver, K. A.

doi:10.1086/380899

Cited by 210 publications

(341 citation statements)

References 54 publications

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“…Fitting the CLF of the bulge of M 31, Shirey et al (2001) find a slope of 1.77 ± 0.35 for 37.4 ≤ log L X erg s −1 < 38.1, flattening to α = 0.43 for log L X erg s −1 < 37.4. According to the surveys of Colbert et al (2004) and Kilgard et al (2002) galaxies with ongoing or recent star formation show flatter CLFs than elliptical galaxies consisting of old populations. Comparing the slope of the bulge CLF from Shirey et al (2001) with those of the disc from this work (see Table 6) show that the CLF of the disc is flatter than that of the core.…”

Section: Luminosity Functionsmentioning

confidence: 99%

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: 99%

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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“…The reason for this is that the detection of HMXBs in M 31 is difficult. Colbert et al (2004) showed that the hardness ratio method is very inefficient in selecting HMXBs in spiral galaxies. The selection process is complicated by the fact, that the spectral properties of BH HMXBs, which have power-law spectra with indices of ∼1-∼2 are similar to LMXBs and AGN.…”

Section: Detection Of High Mass X-ray Binariesmentioning

confidence: 99%

“…Therefore the region in the HR diagrams where BH HMXB are located is contaminated by other hard sources (LMXBs, AGN, and Crab-like SNRs). For the NS HMXBs, which have power-law indices of ∼1, and thus should be easier to select, the uncertainties in the hardness ratios lead at best to an overlap -in the worst case to a fusion -with the area occupied by other hard sources (Colbert et al 2004). …”

Section: Detection Of High Mass X-ray Binariesmentioning

confidence: 99%

The deepXMM-NewtonSurvey of M 31

Stiele

Pietsch

Haberl

et al. 2011

A&A

150

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Aims. The largest Local Group spiral galaxy, M 31, has been completely imaged for the first time, obtaining a luminosity lower limit ∼10 35 erg s −1 in the 0.2-4.5 keV band. Our XMM-Newton EPIC survey combines archival observations along the major axis, from The main goal of the paper is to study the X-ray source population of M 31.Methods. An X-ray catalogue of 1897 sources was created, with 914 detected for the first time. Source classification and identification were based on X-ray hardness ratios, spatial extent of the sources, and cross correlation with catalogues in the X-ray, optical, infrared, and radio wavelengths. We also analysed the long-term variability of the X-ray sources and this variability allows us to distinguish between X-ray binaries and active galactic nuclei (AGN). Furthermore, supernova remnant classifications of previous studies that did not use long-term variability as a classification criterion could be validated. Including previous Chandra and ROSAT observations in the long-term variability study allowed us to detect additional transient or at least highly variable sources, which are good candidate X-ray binaries. Results. Fourteen of the 30 supersoft source (SSS) candidates represent supersoft emission of optical novae. Many of the 25 supernova remnants (SNRs) and 31 SNR candidates lie within the 10 kpc dust ring and other star-forming regions in M 31. This connection between SNRs and star-forming regions implies that most of the remnants originate in type II supernovae. The brightest sources in X-rays in M 31 belong to the class of X-ray binaries (XRBs). Ten low-mass XRBs (LMXBs) and 26 LMXB candidates were identified based on their temporal variability. In addition, 36 LMXBs and 17 LMXB candidates were identified owing to correlations with globular clusters and globular cluster candidates. From optical and X-ray colour-colour diagrams, possible high-mass XRB (HMXB) candidates were selected. Two of these candidates have an X-ray spectrum as is expected for an HMXB containing a neutron star primary. Conclusions. While our survey has greatly improved our understanding of the X-ray source populations in M 31, at this point 65% of the sources can still only be classified as "hard" sources; i.e. it is not possible to decide whether these sources are X-ray binaries or Crab-like supernova remnants in M 31 or X-ray sources in the background. Deeper observations in X-ray and at other wavelengths would help classify these sources.

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“…Previous studies of the X-ray emission produced by starformation have been focused on nearby starbursts (e.g., Ptak et al 1999;Jiménez-Bailón et al 2003;Ranalli et al 2003;Grimm et al 2003;Persic et al 2004;Colbert et al 2004) or ULIRGs (e.g., Rieke 1988;Perez-Olea & Colina 1996;Ptak et al 2003;Franceschini et al 2003;Teng et al 2005;Teng & Veilleux 2010).…”

Section: Introductionmentioning

confidence: 99%

The X-ray emission of local luminous infrared galaxies

Pereira-Santaella

Alonso‐Herrero

Santos-Lleo

et al. 2011

A&A

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We study the X-ray emission of a representative sample of 27 local luminous infrared galaxies (LIRGs). The median IR luminosity of our sample is log L IR /L = 11.2, therefore the low-luminosity end of the LIRG class is well represented. We used new XMM-Newton data as well as Chandra and XMM-Newton archive data. The soft X-ray (0.5-2 keV) emission of most of the galaxies (>80%), including LIRGs hosting a Seyfert 2 nucleus, is dominated by star-formation-related processes. These LIRGs follow the star-formation rate (SFR) versus soft X-ray luminosity correlation observed in local starbursts. We find that ∼15% of the non-Seyfert LIRGs (3 out of 20) have an excessively hard X-ray emission relative to that expected from star-formation, which might indicate the presence of an obscured AGN. The rest of the non-Seyfert LIRGs follow the SFR versus hard X-ray (2-10 keV) luminosity correlation of local starbursts. The non-detection of the 6.4 keV Fe Kα emission line in the non-Seyfert LIRGs allows us to put an upper limit on the bolometric luminosity of an obscured AGN, L bol <10 43 erg s −1 . That is, if these galaxies were hosting a low-luminosity AGN, its contribution to the total luminosity would be less than 10%. Finally we estimate that the AGN contribution to the total luminosity for our sample of local LIRGs is between 7% and 10%.

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Old and Young X‐Ray Point Source Populations in Nearby Galaxies

Cited by 210 publications

References 54 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 deepXMM-NewtonSurvey of M 31

The X-ray emission of local luminous infrared galaxies

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