Ultra-Luminous X-Ray Sources in the Most Metal Poor Galaxies

Prestwich, Andrea; Tsantaki, M.; Zezas, A.; Jackson, Floyd; Roberts, T. P.; Foltz, Ryan; Linden, Tim; Kalogera, V.

doi:10.1088/0004-637x/769/2/92

Cited by 121 publications

(182 citation statements)

References 41 publications

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“…Independent evidence exists for increased numbers of ULXs in lowmetallicity environments (Swartz et al 2008;Mapelli et al 2010;Kaaret et al 2011;Prestwich et al 2013) consistent with what we detect here.…”

Section: Discussionsupporting

confidence: 91%

Exploring X-Ray Binary Populations in Compact Group Galaxies With Chandra

Tzanavaris

Hornschemeier²,

Gallagher

et al. 2016

ApJ

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We obtain total galaxy X-ray luminosities, L X , originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, we find that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the ±1σ scatter of the Mineo et al. L X -star formation rate (SFR) correlation or have higher L X than predicted by this correlation for their SFR. We discuss how these "excesses" may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies are consistent with the Boroson et al. L X -stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low-or high-mass XRBs, we use appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme L X values. We find that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high L X values can be observed due to strong XRB variability.

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Section: Discussionsupporting

confidence: 91%

Exploring X-Ray Binary Populations in Compact Group Galaxies With Chandra

Tzanavaris

Hornschemeier²,

Gallagher

et al. 2016

ApJ

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“…Secondly, we can compare with the detailed calculations by Prestwich et al (2013) and Brorby et al (2014), who show that for other samples of nearby dwarfs (with essentially equivalent data to ours) the probability of finding a background source inside the optical area of a typical dwarf is 1-2 per cent. From this, we would expect 2-4 contaminating X-ray sources in our sample, similar to the figure derived from the number counts.…”

Section: Contaminationmentioning

confidence: 56%

“…Moiseev, Pustilnik & Kniazev 2010). We observe a powerful X-ray source with L X > 10 39 erg s −1 , but it does not appear to have been noted as a Chandra source prior to the work of Prestwich et al (2013) who specifically searched in lowmetallicity systems. The computed hardness ratio is HR −0.8, implying 2.6.…”

Section: Galaxy 678; Sdssj11193436+5130121mentioning

confidence: 75%

“…The X-ray source appears coincident with one of the major bright knots within, but well off-centre of, the image ( 1.2 kpc south of the nominal SDSS coordinates). There appears to have been no previous X-ray detection of this source prior to the specific search by Prestwich et al (2013). It has HR −0.1, or 0.7.…”

Section: Galaxy 1200; Sdssj11320262+5722366mentioning

confidence: 91%

“…above 10 38 erg s −1 ; the three fainter ones are, unsurprisingly, in the two nearest galaxies, less than 10 Mpc away. Four sources are slightly above 10 39 erg s −1 , so might nominally be considered ULX sources (Prestwich et al 2013). However, Walton et al (2011) argue that ULXs in star-forming galaxies are just bright HMXBs, so we do not separate the two here.…”

Section: Field Dwarfsmentioning

confidence: 99%

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X-ray sources in dwarf galaxies in the Virgo cluster and the nearby field

Papadopoulou

Phillipps

Young

2016

Mon. Not. R. Astron. Soc.

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The extent to which dwarf galaxies represent essentially scaled down versions of giant galaxies is an important question with regards the formation and evolution of the galaxy population as a whole. Here, we address the specific question of whether dwarf galaxies behave like smaller versions of giants in terms of their X-ray properties. We discuss two samples of around 100 objects each, dwarfs in the Virgo cluster and dwarfs in a large Northern hemisphere area. We find nine dwarfs in each sample with Chandra detections. For the Virgo sample, these are in dwarf elliptical (or dwarf lenticular) galaxies and we assume that these are (mostly) low-mass X-ray binaries (LMXB) [some may be nuclear sources]. We find a detection rate entirely consistent with scaling down from massive ellipticals, viz. about one bright (i.e. L X > 10 38 erg s −1 ) LMXB per 5 × 10 9 M of stars. For the field sample, we find one (known) Seyfert nucleus, in a galaxy which appears to be the lowest mass dwarf with a confirmed X-ray emitting nucleus. The other detections are in star-forming dwarf irregular or blue compact dwarf galaxies and are presumably high-mass X-ray binaries (HMXB). This time, we find a very similar detection rate to that in large late-type galaxies if we scale down by star formation rate, roughly one HMXB for a rate of 0.3 M per year. Nevertheless, there does seem to be one clear difference, in that the dwarf late-type galaxies with X-ray sources appear strongly biased to very low metallicity systems.

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Star Formation for Predictive Primordial Galaxy Formation

Milosavljević

Safranek-Shrader

2016

Understanding the Epoch of Cosmic Reionization

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The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization.Here we review the current understanding of early star formation, emphasizing unsolved problems and technical challenges. We begin with the first generation of stars to form after the Big Bang and trace how they influenced subsequent star formation. The onset of chemical enrichment coincided with a sharp increase in the overall physical complexity of star forming systems. Ab-initio computational treatments are just now entering the domain of the predictive and are establishing contact with local observations of the relics of this ancient epoch.

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Ultra-Luminous X-Ray Sources in the Most Metal Poor Galaxies

Abstract: arXiv:1302.6203v1 [astro-ph.HE]

Cited by 121 publications

References 41 publications

Exploring X-Ray Binary Populations in Compact Group Galaxies With Chandra

Exploring X-Ray Binary Populations in Compact Group Galaxies With Chandra

X-ray sources in dwarf galaxies in the Virgo cluster and the nearby field

Star Formation for Predictive Primordial Galaxy Formation

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