2005A&A...432..999V


Query : 2005A&A...432..999V

2005A&A...432..999V - Astronomy and Astrophysics, volume 432, 999-1012 (2005/3-4)

XMM-Newton X-ray spectroscopy of the high-mass X-ray binary 4U 1700-37 at low flux.

VAN DER MEER A., KAPER L., DI SALVO T., MENDEZ M., VAN DER KLIS M., BARR P. and TRAMS N.R.

Abstract (from CDS):

We present results of a monitoring campaign of the high-mass X-ray binary system 4U 1700-37/HD 153919, carried out with XMM-Newton in February 2001. The system was observed at four orbital phase intervals, covering 37% of one 3.41-day orbit. The lightcurve includes strong flares, commonly observed in this source. We focus on three epochs in which the data are not affected by photon pile up: the eclipse, the eclipse egress and a low-flux interval in the lightcurve around orbital phase φ∼0.25. The high-energy part of the continuum is modelled as a direct plus a scattered component, each represented by a power law with identical photon index (α∼1.4), but with different absorption columns. We show that during the low-flux interval the continuum is strongly reduced, probably due to a reduction of the accretion rate onto the compact object. A soft excess is detected in all spectra, consistent with either another continuum component originating in the outskirts of the system or a blend of emission lines. Many fluorescence emission lines from near-neutral species and discrete recombination lines from He- and H-like species are detected during eclipse and egress. The fluorescence Fe Kα line at 6.4keV is very prominent; a second Kα line is detected at slightly higher energies (up to 6.7keV) and a Kβ line at 7.1keV. In the low-flux interval the Fe Kα line at 6.4keV is strongly (factor ∼30) reduced in strength. In eclipse, the Fe Kβ/Kα ratio is consistent with a value of 0.13. In egress we initially measure a higher ratio, which can be explained by a shift in energy of the Fe K-edge to ∼ 7.15keV, which is consistent with moderately ionised iron, rather than neutral iron, as expected for the stellar wind medium. The detection of recombination lines during eclipse indicates the presence of an extended ionised region surrounding the compact object. The observed increase in strength of some emission lines corresponding to higher values of the ionisation parameter ξ further substantiates this conclusion.

Abstract Copyright:

Journal keyword(s): stars: binaries: eclipsing - stars: individual: 4U 1700-37 - stars: individual: HD 153919 - accretion, accretion disks - scattering

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6560 1
2 X LMC X-4 HXB 05 32 49.5556042296 -66 22 13.202721768   13.9 14.0     O8III 649 0
3 V* GP Vel HXB 09 02 06.8608812864 -40 33 16.899168060 6.85 7.37 6.87 6.31 6.05 B0.5Ia 1453 0
4 V* V779 Cen HXB 11 21 15.0920532528 -60 37 25.630264596   14.4 12.27     O9III/Veq 1048 0
5 V* BP Cru HXB 12 26 37.5605188992 -62 46 13.261044684   12.70 10.66     B1.5Iaeq 657 0
6 HD 153919 HXB 17 03 56.7725629224 -37 50 38.913331452 6.06 6.78 6.51 6.08 5.90 O6Iafcp 793 1
7 4U 1907+09 HXB 19 09 37.1382681824 +09 49 55.279554289   19.41 16.35 14.40 12.53 O8.5Iab 329 1
8 HD 226868 HXB 19 58 21.6757355952 +35 12 05.784512688 9.38 9.72 8.91 8.42   O9.7Iabpvar 4188 0
9 V* V1521 Cyg HXB 20 32 25.78 +40 57 27.9           WN4/5-6/7 1883 2

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2023.02.01-19:51:06

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