TY - JOUR
T1 - Extended X-ray emission in the vicinity of the microquasar LS 5039
T2 - Pulsar wind nebula?
AU - Durant, Martin
AU - Kargaltsev, Oleg
AU - Pavlov, George G.
AU - Chang, Chulhoon
AU - Garmire, Gordon P.
PY - 2011/7/1
Y1 - 2011/7/1
N2 - LS5039 is a high-mass binary with a period of 4 days, containing a compact object and an O-star, one of the few high-mass binaries detected in γ-rays. Our Chandra Advanced CCD Imaging Spectrometer observation of LS 5039 provided a high-significance (10σ) detection of extended emission clearly visible for up to 1′ from the point source. The spectrum of this emission can be described by an absorbed power-law model with photon index Γ = 1.9 0.3, somewhat softer than the point-source spectrum Γ = 1.44 0.07, with the same absorption, NH = (6.4 0.6) × 10 21cm-2. The observed 0.5-8keV flux of the extended emission is ≃ 8.8 × 10-14ergs-1cm-2 or 5% of the point-source flux; the latter is a factor of 2 lower than the lowest flux detected so far. Fainter extended emission with comparable flux and a softer (Γ 3) spectrum is detected at even greater radii (up to 2′). Two possible interpretations of the extended emission are a dust scattering halo and a synchrotron nebula powered by energetic particles escaping the binary. We discuss both of these scenarios and favor the nebula interpretation, although some dust contribution is possible. We have also found transient sources located within a narrow stripe south of LS 5039. We discuss the likelihood of these sources to be related to LS5039.
AB - LS5039 is a high-mass binary with a period of 4 days, containing a compact object and an O-star, one of the few high-mass binaries detected in γ-rays. Our Chandra Advanced CCD Imaging Spectrometer observation of LS 5039 provided a high-significance (10σ) detection of extended emission clearly visible for up to 1′ from the point source. The spectrum of this emission can be described by an absorbed power-law model with photon index Γ = 1.9 0.3, somewhat softer than the point-source spectrum Γ = 1.44 0.07, with the same absorption, NH = (6.4 0.6) × 10 21cm-2. The observed 0.5-8keV flux of the extended emission is ≃ 8.8 × 10-14ergs-1cm-2 or 5% of the point-source flux; the latter is a factor of 2 lower than the lowest flux detected so far. Fainter extended emission with comparable flux and a softer (Γ 3) spectrum is detected at even greater radii (up to 2′). Two possible interpretations of the extended emission are a dust scattering halo and a synchrotron nebula powered by energetic particles escaping the binary. We discuss both of these scenarios and favor the nebula interpretation, although some dust contribution is possible. We have also found transient sources located within a narrow stripe south of LS 5039. We discuss the likelihood of these sources to be related to LS5039.
UR - http://www.scopus.com/inward/record.url?scp=79960004060&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79960004060&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/735/1/58
DO - 10.1088/0004-637X/735/1/58
M3 - Article
AN - SCOPUS:79960004060
SN - 0004-637X
VL - 735
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 58
ER -