An Fe XXVI Absorption Line in the Persistent Spectrum of the Dipping Low Mass X-ray Binary 1A 1744-361 - Astrophysics > High Energy Astrophysical PhenomenaReportar como inadecuado




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Abstract: We report on Chandra X-ray Observatory CXO High-Energy Transmission GratingHETG spectra of the dipping Low Mass X-ray Binary LMXB 1A 1744-361 duringits July 2008 outburst. We find that its persistent emission is well modeled bya blackbody kT ~ 1.0 keV plus power-law $\Gamma$ ~ 1.7 with an absorptionedge at 7.6 keV. In the residuals of the combined spectrum we find asignificant absorption line at 6.961+-0.002 keV, consistent with the Fe XXVIhydrogen-like Fe 2 - 1 transition. We place an upper limit on the velocity ofa redshifted flow of v < 221 km-s. We find an equivalent width for the line of27^+2 -3 eV, from which we determine a column density of 7+-1x10^17 cm^-2 viaa curve-of-growth analysis. Using XSTAR simulations, we place a lower limit onthe ionization parameter of > 10^3.6 erg cm-s. The properties of this line areconsistent with those observed in other dipping LMXBs. Using Rossi X-ray TimingExplorer RXTE data accumulated during this latest outburst we present anupdated color-color diagram which clearly shows that 1A 1744-361 is an -atoll-source. Finally, using additional dips found in the RXTE and CXO data weprovide an updated orbital period estimate of 52+-5 minutes.



Autor: Fotis P. Gavriil GSFC-UMBC, Tod E. Strohmayer NASA-GSFC, Sudip Bhattacharyya Tata Institute of Fundamental Research

Fuente: https://arxiv.org/







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