Query : 2008A&A...478..181L

2008A&A...478..181L - Astronomy and Astrophysics, volume 478, 181-186 (2008/1-4)

Spectral analysis of LMC X-2 with XMM/Newton: unveiling the emission process in the extragalactic Z-source.


Abstract (from CDS):

We present the results of the analysis of an archival observation of LMC X-2 performed with XMM/Newton. The spectra taken by high-precision instruments have never been analyzed before. We find an X-ray position for the source that is inconsistent with the one obtained by ROSAT, but in agreement with the Einstein position and that of the optical counterpart. The correlated spectral and timing behaviour of the source suggests that the source is probably in the normal branch of its X-ray color-color diagram. The spectrum of the source can be fitted with a blackbody with a temperature 1.5keV plus a disc blackbody at 0.8keV. Photoelectric absorption from neutral matter has an equivalent hydrogen column of 4x1020cm–2. An emission line, which we identify as the O VIII Lyman-α line, is detected, while no feature due to iron is detected in the spectrum. We argue that the emission of this source can be straightforwardly interpreted as the sum of the emission from a boundary layer between the NS and the disc and a blackbody component coming from the disc itself. Other canonical models that are used to fit Z-sources do not give a satisfactory fit to the data. The detection of the O VIII emission line (and the lack of detection of lines in the iron region) can be due to the fact that the source lies in the Large Magellanic Cloud.

Abstract Copyright:

Journal keyword(s): X-rays: binaries - accretion, accretion disks - line: identification - stars: neutron

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 X LMC X-2 LXB 05 20 28.04 -71 57 53.3 17.20 18.00 18.0     ~ 181 0
2 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16977 1
3 V* V818 Sco LXB 16 19 55.0692669024 -15 38 25.017666540 11.60 12.40 11.1     Oev 1618 0
4 4U 1642-45 LXB 16 45 47.7 -45 36 40     14.30     ~ 407 1
5 4U 1758-25 LXB 18 01 09.7308060816 -25 04 44.120221284     11.08     ~ 642 1
6 V* V1341 Cyg LXB 21 44 41.1544345272 +38 19 17.066570988 15.00 15.13 14.68 15.00   A9III 1136 1

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