Polarized infrared emission from X-ray binary jets
Near-infrared (NIR) and optical polarimetric observations of a selection of X-ray binaries are presented. The targets were observed using the Very Large Telescope and the United Kingdom Infrared Telescope. We detect a significant level (3σ) of linear polarization in four sources. The polarization is...
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Published in | Monthly notices of the Royal Astronomical Society Vol. 387; no. 2; pp. 713 - 723 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.06.2008
Blackwell Science Oxford University Press |
Subjects | |
Online Access | Get full text |
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Summary: | Near-infrared (NIR) and optical polarimetric observations of a selection of X-ray binaries are presented. The targets were observed using the Very Large Telescope and the United Kingdom Infrared Telescope. We detect a significant level (3σ) of linear polarization in four sources. The polarization is found to be intrinsic (at the >3σ level) in two sources; GRO J1655−40 (∼4–7 per cent in the H and Ks bands during an outburst) and Sco X–1 (∼0.1–0.9 per cent in the H and K bands), which is stronger at lower frequencies. This is likely to be the signature of optically thin synchrotron emission from the collimated jets in these systems, whose presence indicates that a partially ordered magnetic field is present at the inner regions of the jets. In Sco X−1, the intrinsic polarization is variable (and sometimes absent) in the H and K bands. In the J band (i.e. at higher frequencies), the polarization is not significantly variable and is consistent with an interstellar origin. The optical light from GX 339–4 is also polarized, but at a level and position angle consistent with scattering by interstellar dust. The other polarized source is SS 433, which has a low level (0.5–0.8 per cent) of J-band polarization, likely due to local scattering. The NIR counterparts of GRO J0422+32, XTE J1118+480, 4U 0614+09 and Aql X–1 (which were all in or near quiescence) have a linear polarization level of <16 per cent (3σ upper limit, some are <6 per cent). We discuss how such observations may be used to constrain the ordering of the magnetic field close to the base of the jet in such systems. |
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Bibliography: | ark:/67375/HXZ-3B79GQGM-V istex:0ABDE6B63837B30D0FC9ED7F17CD84C9EE6C1236 Based on observations collected at the European Southern Observatory, Chile, under ESO Programme IDs 076.D-0497 and 275.D-5062. Based on observations collected at the European Southern Observatory, Chile, under ESO Programme IDs 076.D‐0497 and 275.D‐5062. ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0035-8711 1365-2966 |
DOI: | 10.1111/j.1365-2966.2008.13254.x |