Astronomy from Space

Trümper, J.; Fazio, G. G.; Hutchings, J. B.; Schönfelder, V.; Jordan, S. D.

doi:10.1007/978-94-011-1100-3_33

Cited by 43 publications

(59 citation statements)

References 45 publications

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“…3. Scattering of X-rays in these proximity zones will result in X-ray halos around each source, similar to the dust halos observed around many X-ray sources (Overbeck 1965;Trümper & Schönfelder 1973;Rolf 1983;Predehl & Schmitt 1995) at angles < 1 • but extending to much larger angles. The profile is sharply peaked if the source is in the Galactic plane and the slice through the plane crosses the source.…”

Section: Ism Volume Emissivitysupporting

confidence: 59%

A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries

Molaro

Khatri

Sunyaev

2014

A&A

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We predict a thin diffuse component of the Galactic Ridge X-ray emission (GRXE) arising from the scattering of the radiation of bright X-ray binaries (XBs) by the interstellar medium. This scattered component has the same scale height as that of the gaseous disk (∼ 80 pc) and is therefore thinner than the GRXE of stellar origin (scale height ∼ 130 pc). The morphology of the scattered component is furthermore expected to trace the clumpy molecular and HI clouds. We calculate this contribution to the GRXE from known Galactic XBs assuming that they are all persistent. The known XBs sample is incomplete, however, because it is flux limited and spans the lifetime of X-ray astronomy (∼ 50 years), which is very short compared with the characteristic time of 1000-10000 years that would have contributed to the diffuse emission observed today due to time delays. We therefore also use a simulated sample of sources, to estimate the diffuse emission we should expect in an optimistic case assuming that the X-ray luminosity of our Galaxy is on average similar to that of other galaxies. In the calculations we also take into account the enhancement of the total scattering cross-section due to coherence effects in the elastic scattering from multi-electron atoms and molecules. This scattered emission can be distinguished from the contribution of low X-ray luminosity stars by the presence of narrow fluorescent K-α lines of Fe, Si, and other abundant elements present in the interstellar medium and by directly resolving the contribution of low X-ray luminosity stars. We find that within 1• latitude of the Galactic plane the scattered emission contributes on average 10 − 30% of the GRXE flux in the case of known sources and over 50% in the case of simulated sources. In the latter case, the scattered component is found to even dominate the stellar emission in certain parts of the Galactic plane. X-rays with energies 1 keV from XBs should also penetrate deep inside the HI and molecular clouds, where they are absorbed and heat the interstellar medium. We find that this heating rate dominates the heating by cosmic rays (assuming a solar neighborhood energy density) in a considerable part of the Galaxy.

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Section: Ism Volume Emissivitysupporting

confidence: 59%

A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries

Molaro

Khatri

Sunyaev

2014

A&A

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“…The idea that dust grains along the LOS can produce an observable halo around X-ray sources, the so called 'dust scattering halo', was proposed fifty years ago (Overbeck 1965;Trümper & Schönfelder 1973) and was first observed by the Einstein satellite around GX 339-4 (Rolf 1983). The investigation of the dust scattering halo can provide important information about the location of the dust along the LOS as well as the size and composition of the dust grains (e.g.…”

Section: Dust Scattering Halo In X-raysmentioning

confidence: 99%

“…A dust scattering halo will show variability if the source is variable (Trümper & Schönfelder 1973;Mao, Ling & Zhang 2014;Heinz et al 2015;Vasilopoulos & Petropoulou 2016). Time lags are caused by the arrival time differences of scattering photons with different light paths (Xu, McCray & Kelley 1986).…”

Section: Variability Of the Dust Scattering Halomentioning

confidence: 99%

Probing the interstellar dust towards the Galactic Centre: dust-scattering halo around AX J1745.6−2901

Jin

Ponti

Haberl

et al. 2017

Monthly Notices of the Royal Astronomical Society

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AX J1745.6-2901 is an X-ray binary located at only 1.45 arcmin from Sgr A ⋆ , showcasing a strong X-ray dust scattering halo. We combine Chandra and XMM-Newton observations to study the halo around this X-ray binary. Our study shows two major thick dust layers along the line of sight (LOS) towards AX J1745.6-2901. The LOS position and N H of these two layers depend on the dust grain models with different grain size distribution and abundances. But for all the 19 dust grain models considered, dust Layer-1 is consistently found to be within a fractional distance of 0.11 (mean value: 0.05) to AX J1745.6-2901 and contains only (19-34)% (mean value: 26%) of the total LOS dust. The remaining dust is contained in Layer-2, which is distributed from the Earth up to a mean fractional distance of 0.64. A significant separation between the two layers is found for all the dust grain models, with a mean fractional distance of 0.31. Besides, an extended wing component is discovered in the halo, which implies a higher fraction of dust grains with typical sizes 590Å than considered in current dust grain models. Assuming AX J1745.6-2901 is 8 kpc away, dust Layer-2 would be located in the Galactic disk several kpc away from the Galactic Centre (GC). The dust scattering halo biases the observed spectrum of AX J1745.6-2901 severely in both spectral shape and flux, and also introduces a strong dependence on the size of the instrumental point spread function and the source extraction region. We build Xspec models to account for this spectral bias, which allow us to recover the intrinsic spectrum of AX J1745.6-2901 free from dust scattering opacity. If dust Layer-2 also intervenes along the LOS to Sgr A ⋆ and other nearby GC sources, a significant spectral correction for the dust scattering opacity would be necessary for all these GC sources.

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“…This situation is complicated by the fact that SgrA * is variable, flaring on the order of once per day for hours at a time (e.g., Neilsen et al 2013) and impacting neutral gas in the vicinity of the GC (e.g., Krivonos et al 2016). The dust-scattering halo around SgrA * will also vary temporally, based on the light curve of SgrA * and the locations of foreground dusty material (e.g., Trümper & Schönfelder 1973;Tiengo et al 2010;Heinz et al 2015Heinz et al , 2016.…”

Section: Introductionmentioning

confidence: 99%

The Chandra Dust-scattering Halo of Galactic Center Transient Swift J174540.7–290015

Corrales

Mon

Haggard

et al. 2017

ApJ

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We report the detection of a dust-scattering halo around a recently discovered X-ray transient, Swift J174540.7-290015, which in early 2016 February underwent one of the brightest outbursts (F X ≈ 5 × 10 −10 erg cm −2 s −1 ) observed from a compact object in the Galactic Center field. We analyze four Chandra images that were taken as follow-up observations to Swift discoveries of new Galactic Center transients. After adjusting our spectral extraction for the effects of detector pile-up, we construct a point-spread function for each observation and compare it to the GC field before the outburst. We find residual surface brightness around Swift J174540.7-290015, which has a shape and temporal evolution consistent with the behavior expected from X-rays scattered by foreground dust. We examine the spectral properties of the source, which shows evidence that the object transitioned from a soft to hard spectral state as it faded below L X ∼10 36 ergs −1 . This behavior is consistent with the hypothesis that the object is a low-mass X-ray binary in the Galactic Center.

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Astronomy from Space

Cited by 43 publications

References 45 publications

A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries

A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries

Probing the interstellar dust towards the Galactic Centre: dust-scattering halo around AX J1745.6−2901

The Chandra Dust-scattering Halo of Galactic Center Transient Swift J174540.7–290015

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