A Complete Sample of Ultraluminous X-Ray Source Host Galaxies

Swartz, Douglas A.; Soria, Roberto; Tennant, Allyn F.; Yukita, Mihoko

doi:10.1088/0004-637x/741/1/49

Cited by 203 publications

(327 citation statements)

References 51 publications

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“…As can be seen by comparing Figure 2 We estimate the flux of each 3σ-detected source assuming a power law with a photon index of Γ = 1.7 (Swartz et al 2004;Soria 2011). Their luminosities (Table 1) put them in the range of ultra-luminous X-ray sources (ULXs; commonly associated with star forming galaxies Swartz et al 2011;Luangtip Figure 2. (a) Extraction regions for both bright point-like sources W1-3, E1-5, and B1 associated with the southwestern galaxy UGC 12914, northeastern galaxy UGC 12915, and the bridge region, respectively; and the extended regions extracted (see Table 1).…”

Section: The Compact Sourcesmentioning

confidence: 99%

X-Ray Emission From the Taffy (Vv254) Galaxies and Bridge

Appleton

Lanz

Bitsakis

et al. 2015

ApJ

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We present the first X-ray observations of the Taffy galaxies (UGC 12914/5) with the Chandra observatory and detect soft X-ray emission in the region of the gas-rich, radio-continuum-emitting Taffy bridge. The results are compared to Herschel observations of dust and diffuse [C II] line-emitting gas. The diffuse component of the Taffy bridge has an X-ray luminosity of L X 0.5 8 keV, which accounts for 19% of the luminosity of the sum for the two galaxies. The total mass in hot gas is (0.8-1.3) × 10 8 M e , which is approximately 1% of the total (H I + H 2 ) gas mass in the bridge, and ∼11% of the mass of warm molecular hydrogen discovered by Spitzer. The soft X-ray and dense CO-emitting gas in the bridge have offset distributions, with the X-rays peaking along the northwestern side of the bridge in the region where stronger far-IR dust and diffuse [C II] gas is observed by Herschel. We detect nine Ultra Luminous X-ray sources in the system, the brightest of which is found in the bridge, associated with an extragalactic H II region. We suggest that the X-ray-emitting gas has been shockedheated to high temperatures and "splashed" into the bridge by the collision. The large amount of gas stripped from the galaxies into the bridge and its very long gas depletion timescale (>10 Gyr) may explain why this system, unlike most major mergers, is not a powerful IR emitter.

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Section: The Compact Sourcesmentioning

confidence: 99%

X-Ray Emission From the Taffy (Vv254) Galaxies and Bridge

Appleton

Lanz

Bitsakis

et al. 2015

ApJ

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“…The first source is located in a star-forming region of the galaxy classified as a late-type dwarf spiral at a distance of 6.8 Mpc (Drozdovsky & Karachentsev 2000). The source NGC 5474 X-1 is identified as a ULX by Swartz et al (2011), with an X-ray luminosity of LX ≃ 1.4× 10 40 erg s −1 . The second ULX is located on the edge of the disc of M66, which is an SAb-type barred galaxy at a distance of 10.6 Mpc (Lee & Jang 2013).…”

Section: Introductionmentioning

confidence: 99%

Optical counterparts of two ULXs in NGC 5474 and NGC 3627 (M 66)

Avdan,

Vinokurov,

Fabrika

et al. 2015

Monthly Notices of the Royal Astronomical Society: Letters

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We identified two optical counterparts of brightest ultraluminous X-ray Sources (ULXs) in galaxies NGC 5474 and NGC 3627 (M66). The counterparts in Hubble Space Telescope images are very faint, their V magnitudes are 24.7 (M V ≈ −4.5) and 25.9 (M V ≈ −4.2), respectively. NGC 5474 X-1 changes the X-ray flux more than two orders of magnitude, in its bright state it has L X ≈ 1.6 × 10 40 erg s −1 , the spectrum is best fitted by an absorbed power-law model with a photon index Γ ≈ 0.94. M66 X-1 varies in X-rays with a factor of ∼ 2.5, its maximal luminosity being 2.0 × 10 40 erg s −1 with Γ ≈ 1.7. Optical spectroscopy of the NGC 5474 X-1 has shown a blue spectrum, which however was contaminated by a nearby star of 23 mag, but the counterpart has a redder spectrum. Among other objects captured by the slit are a background emission-line galaxy (z = 0.359) and a new young cluster of NGC 5474. We find that these two ULXs have largest X-ray-to-optical ratios of L X /L opt ∼ 7000 for NGC 5474 X-1 (in its bright state) and 8000 for M66 X-1 both with the faintest optical counterparts ever measured. Probably their optical emission originates from the donor star. If they have super-Eddington accretion discs with stellar-mass black holes, they may also have the lowest mass accretion rates among ULXs such as in M81 X-6 and NGC 1313 X-1.

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“…Such low metallicities are required in order to make more massive BHs (e.g., Heger et al 2003), which shows that it would be possible for ULXs to be massive stellar remnant BHs. Yet, population studies of the HMXB population of the local universe has also revealed an unbroken power-law slope in the XLF up to ∼ 2 × 10 40 erg s −1 (e.g., Grimm et al 2003;Swartz et al 2011;Mineo et al 2012). This continuation indicates that the majority of ULXs with L X < 2 × 10 40 erg s −1 are likely to be HMXBs with a stellar-mass BH accreting at around or above the Eddington limit.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Nature of the Ulx and X-Ray Population of the Spiral Galaxy NGC 4088

Mezcua

Fabbiano

Gladstone

et al. 2014

ApJ

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We present the first Chandra and Swift X-ray study of the spiral galaxy NGC 4088 and its ultraluminous X-ray source (ULX N4088-X1). We also report very long baseline interferometry (VLBI) observations at 1.6 and 5 GHz performed quasi-simultaneously with the Swift and Chandra observations, respectively. Fifteen X-ray sources are detected by Chandra within the D25 ellipse of NGC 4088, from which we derive the X-ray luminosity function (XLF) of this galaxy. We find the XLF is very similar to those of star-forming galaxies and estimate a star-formation rate of 4.5 M yr −1 . The Chandra detection of the ULX yields its most accurate X-ray position, which is spatially coincident with compact radio emission at 1.6 GHz. The ULX Chandra X-ray luminosity, L 0.2−10.0keV = 3.4 × 10 39 erg s −1 , indicates that N4088-X1 could be located at the high-luminosity end of the high-mass X-ray binary (HMXB) population of NGC 4088. The estimates of the black hole mass and ratio of radio to X-ray luminosity of N4088-X1 rule out a supermassive black hole nature. The Swift X-ray spectrum of N4088-X1 is best described by a thermal Comptonization model and presents a statistically significant high-energy cut-off. We conclude that N4088-X1 is most likely a stellar remnant black hole in a HMXB, probably fed by Roche lobe overflow, residing in a super-Eddington ultraluminous state. The 1.6 GHz VLBI source is consistent with radio emission from possible ballistic jet ejections in this state.

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A Complete Sample of Ultraluminous X-Ray Source Host Galaxies

Cited by 203 publications

References 51 publications

X-Ray Emission From the Taffy (Vv254) Galaxies and Bridge

X-Ray Emission From the Taffy (Vv254) Galaxies and Bridge

Optical counterparts of two ULXs in NGC 5474 and NGC 3627 (M 66)

Revealing the Nature of the Ulx and X-Ray Population of the Spiral Galaxy NGC 4088

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