A VARIABLE MID-INFRARED SYNCHROTRON BREAK ASSOCIATED WITH THE COMPACT JET IN GX 339-4

作者：Gandhi P^*; Blain A W; Russell D M; Casella P; Malzac J; Corbel S; D'Avanzo P; Lewis F W; Markoff S; Cadolle Bel M; Goldoni P; Wachter S; Khangulyan D; Mainzer A

来源：Astrophysical Journal Letters, 2011, 740(1): L13.

DOI：10.1088/2041-8205/740/1/L13

• accretion, accretion disks
• infrared: general
• radiation mechanisms: non-thermal
• stars: individual (GX339-4)
• X-rays: binaries

Many X-ray binaries remain undetected in the mid-infrared, a regime where emission from their compact jets is likely to dominate. Here, we report the detection of the black hole binary GX 339-4 with the Wide-field Infrared Survey Explorer (WISE) during a very bright, hard accretion state in 2010. Combined with a rich contemporaneous multiwavelength data set, clear spectral curvature is found in the infrared, associated with the peak flux density expected from the compact jet. An optically thin slope of similar to-0.7 and a jet radiative power of >6 x 10(35) erg s(-1) (d/8 kpc)(2) are measured. A similar to 24 hr WISE light curve shows dramatic variations in mid-infrared spectral slope on timescales at least as short as the satellite orbital period similar to 95 minutes. There is also significant change during one pair of observations spaced by only 11 s. These variations imply that the spectral break associated with the transition from self-absorbed to optically thin jet synchrotron radiation must be varying across the full wavelength range of similar to 3-22 mu m that WISE is sensitive to, and more. Based on four-band simultaneous mid-infrared detections, the break is constrained to frequencies of approximate to 4.6(-2.0)(+3.5) x 10(13) Hz in at least two epochs of observation, consistent with a magnetic field B approximate to 1.5(+/- 0.8) x 10(4) G assuming a single-zone synchrotron emission region. The observed variability implies that either B or the size of the acceleration zone above the jet base is being modulated by factors of similar to 10 on relatively short timescales.

• 出版日期2011-10-10
• 单位中国地震局