Detection of the first thermonuclear X-ray burst from AX J1754.2-2754

Человеков, И. В.; Гребенев, С. А.

doi:10.1134/s1063773707120043

Cited by 38 publications

(32 citation statements)

References 8 publications

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“…At the time, the source could not be associated with any of the known X-ray sources from the Einstein or ROSAT catalogues and remained unclassified. INTEGRAL detected a thermonuclear X-ray burst from AX J1754.2-2754 in 2005 (which was reported in 2007 after we submitted our target list for this program; Chelovekov & Grebenev 2007). This unambiguously identified the previously unclassified ASCA source as a neutron star accreting from a (sub-) solar mass companion star: a so-called low-mass X-ray binary (LMXB).…”

Section: Ax J17542-2754mentioning

confidence: 97%

“…This unambiguously identified the previously unclassified ASCA source as a neutron star accreting from a (sub-) solar mass companion star: a so-called low-mass X-ray binary (LMXB). This also allowed for a distance estimate of D 9.2 kpc (Chelovekov & Grebenev 2007).…”

Section: Ax J17542-2754mentioning

confidence: 99%

“…We give both the Galactic (N Gal H ; from Kalberla et al 2005) and observed (N H ) hydrogen column density for each source. The X-ray luminosity is expressed in units of 10 34 erg s −1 and calculated from the unabsorbed flux (F X,unabs ) by assuming a distance of D = 8 kpc for all sources, except AX J1754.2-2754 for which we adopt D = 9.2 kpc (Chelovekov & Grebenev 2007). excess of photons visible by eye within the 2.5-σ ASCA error circle.…”

Section: X-ray Detected Sourcesmentioning

confidence: 99%

“…A&A 540, A22 (2012) The luminosity range traced by the unclassified ASCA sources suggests that a variety of source types might be amongst them. For example, it covers the intensities typically seen for strongly magnetised neutron stars (magnetars), bright magnetically accreting white dwarfs (polars and intermediate polars), sub-luminous X-ray binaries and X-ray emitting massive stars (e.g., Maeda et al 1996;Ezuka & Ishida 1999;Wijnands et al 2006;Chelovekov & Grebenev 2007;Gelfand & Gaensler 2007;Zurita Heras & Chaty 2008;Kaur et al 2010;Degenaar & Wijnands 2009;Anderson et al 2011). In addition, the sample may contain foreground stars or background active galactic nuclei (AGN).…”

Section: Introductionmentioning

confidence: 99%

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Swiftfollow-up observations of unclassified ASCA sources

Degenaar

Starling

Evans

et al. 2012

A&A

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We present Swift follow-up observations of a sample of 35 unclassified faint X-ray sources drawn from the ASCA Galactic centre and Galactic plane surveys. Our short, pointed XRT observations allow detections down to a limiting 0.3-10 keV flux of F X ∼ 10 −13 erg cm −2 s −1 , which translates into a luminosity of L X ∼ 10 33 erg s −1 for an assumed distance of D = 8 kpc. The brightest source in our sample reaches a maximum 0.3-10 keV luminosity of L X ∼ 2 × 10 36 (D/8 kpc) 2 erg s −1 during our Swift observations. We detect 16 (46%) of the ASCA sources with the XRT, while 19 were not detected during our program. Since we are probing the faint end of the ASCA source populations, we expect a large fraction of the non-detections to be due to the Eddington bias. This is strengthened by the fact that we find the observed XRT count rates to be predominantly lower than expected based on the reported ASCA intensities. Nevertheless, investigation of the ASCA properties and any possible long-term X-ray variability leads us to conclude that the nondetections likely include two spurious ASCA detections and three objects that are highly variable or transient X-ray sources. For the 16 XRT-detected sources we obtain positional accuracies of ∼2−4 , which significantly improves upon their ASCA uncertainties of ∼1 . We use the X-ray spectra and variability to characterise these objects. Most appear to be faint, persistent X-ray emitters that have highly absorbed spectra. Based on their X-ray properties we identify three accreting compact objects: one confirmed (AX J1754.2-2754) and one candidate (AX J1538.3-5541) X-ray binary, and one possible magnetically accreting white dwarf (AX J1620.1-5002). Furthermore, we use the improved positions of XRT-detected sources to search for counterparts in simultaneously obtained Swift/UVOT images and possible associations with catalogued sources at various wavelengths. This reveals three possible main sequence stars amongst our sample. The other sources remain unclassified, but our improved XRT positions provide good prospects for dedicated follow-up observations that have the potential to elucidate the nature of these faint, unclassified ASCA sources.

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Section: Ax J17542-2754mentioning

confidence: 97%

Section: Ax J17542-2754mentioning

confidence: 99%

Section: X-ray Detected Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Swiftfollow-up observations of unclassified ASCA sources

Degenaar

Starling

Evans

et al. 2012

A&A

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“…The hypothesis that a significant fraction of the lowluminosity transients are X-ray binaries, gains credence by the detection of thermonuclear X-ray bursts from several of these systems (e.g., in 't Zand et al 1991;Maeda et al 1996;Cocchi et al 1999;Cornelisse et al 2002;Chelovekov & Grebenev 2007;Del Santo et al 2007;Wijnands et al 2009). This establishes that these objects harbor accreting neutron stars, most likely in an LMXB configuration.…”

Section: Introductionmentioning

confidence: 99%

A four-year baselineSwiftstudy of enigmatic X-ray transients located near the Galactic center

Degenaar

Wijnands

2010

A&A

108

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We report on continued monitoring observations of the Galactic center carried out by the X-ray telescope aboard the Swift satellite in 2008 and 2009. This campaign revealed activity of the five known X-ray transients AX J1745.6-2901, CXOGC J174535.5-290124, GRS 1741-2853, XMM J174457-2850.3 and CXOGC J174538.0-290022. All these sources are known to undergo very faint X-ray outbursts with 2-10 keV peak luminosities of L X,peak ∼ 10 34−36 erg s −1 , although the two confirmed neutron star low-mass X-ray binaries AX J1745.6-2901 and GRS 1741-2853 can also become brighter (L X,peak ∼ 10 36−37 erg s −1 ). We discuss the observed longterm lightcurves and X-ray spectra of these five enigmatic transients. In 2008, AX J1745.6-2901 returned to quiescence following an unusually long accretion outburst of more than 1.5 years. GRS 1741-2853 was active in 2009 and displayed the brightest outburst ever recorded for this source, reaching up to a 2-10 keV luminosity of L X ∼ 1 × 10 37 (D/7.2 kpc) 2 erg s −1 . This system appears to undergo recurrent accretion outbursts approximately every 2 years. Furthermore, we find that the unclassified transient XMM J174457-2850.3 becomes bright only during short episodes (days) and is often found active in between quiescence (L X ∼ 10 32 erg s −1 ) and its maximum outburst luminosity of L X ∼ 10 36 erg s −1 . CXOGC J174535.5-290124 and CXOGC J174538.0-290022, as well as three other veryfaint X-ray transients that were detected by Swift monitoring observations in 2006, have very low time-averaged mass-accretion rates of Ṁ long < ∼ 2 × 10 −12 M yr −1 . Despite having obtained two years of new data in 2008 and 2009, no new X-ray transients were detected.

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Low-Mass X-ray Binaries

Bahramian

Degenaar

2023

Handbook of X-Ray and Gamma-Ray Astrophysics

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Detection of the first thermonuclear X-ray burst from AX J1754.2-2754

Cited by 38 publications

References 8 publications

Swiftfollow-up observations of unclassified ASCA sources

Swiftfollow-up observations of unclassified ASCA sources

A four-year baselineSwiftstudy of enigmatic X-ray transients located near the Galactic center

Low-Mass X-ray Binaries

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