Query : 2006A&A...459..901S

2006A&A...459..901S - Astronomy and Astrophysics, volume 459, 901-907 (2006/12-1)

XMM-Newton observation of a spectral state transition in the peculiar radio/X-ray/γ-ray source LS I +61 303.


Abstract (from CDS):

We report the results of XMM-Newton and BeppoSAX observations of the radio and X-ray emitting star LS I +61 303, likely associated with the gamma-ray source 2CG 135+01 and recently detected also at TeV energies. The data include a long XMM-Newton pointing carried out in January 2005, which provides the deepest look ever obtained for this object in the 0.3-12keV range. During this observation the source flux decreased from a high level of ∼13x10–12erg/cm2/s to 4x10–12 erg/cm2/s within 2-3 h. This flux range is the same seen in shorter and less sensitive observations carried out in the past, but the new data show for the first time that transitions between the two levels can occur on short time scales. The flux decrease was accompanied by a significant softening of the spectrum, which is well described by a power law with photon index changing from 1.62±0.01 to 1.83±0.01. A correlation between hardness and intensity is also found when comparing different short observations spanning almost 10 years and covering various orbital phases. LS I +61 303 was detected in the 15-70keV range with the PDS instrument in one of the BeppoSAX observations, providing evidence for variability also in the hard X-ray range. The X-ray spectra, discussed in the context of multiwavelength observations, place some interesting constraints on the properties and location of the high-energy emitting region.

Abstract Copyright:

Journal keyword(s): X-rays: binaries - X-rays: individual: LS I +61 303 - X-rays: individual: GT 0236+610

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 LS I +61 303 HXB 02 40 31.6644419688 +61 13 45.593918580 11.27 11.61 10.75 10.19 9.55 B0Ve 807 2
2 ICRF J024457.6+622806 Sy1 02 44 57.6967097952 +62 28 06.517098084   12.15 12.19     ~ 267 1
3 CPD-63 2495 HXB 13 02 47.6544015048 -63 50 08.626970292 10.34 10.72 9.98 10.03   O9.5Ve 733 0
4 V* V479 Sct HXB 18 26 15.0561548880 -14 50 54.247274304 12.02 12.23 11.27 11.04   ON6V((f))z 535 2

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