2017A&A...600A...8D -
Astronomy and Astrophysics, volume 600A, 8-8 (2017/4-1)
ALMA observations of 4U 1728-34 and 4U 1820-30: first detection of neutron star X-ray binaries at 300 GHz.
DIAZ TRIGO M., MIGLIARI S., MILLER-JONES J.C.A., RAHOUI F., RUSSELL D.M. and TUDOR V.
Abstract (from CDS):
We report on the first observations of neutron star low-mass X-ray binaries with the Atacama Large Millimeter/submillimeter Array (ALMA) at ∼300GHz. Quasi-simultaneous observations of 4U 1728-34 and 4U 1820-30 were performed at radio (ATCA), infrared (VLT) and X-ray (Swift) frequencies, spanning more than eight decades in frequency coverage. Both sources are detected at high significance with ALMA. The spectral energy distribution of 4U 1728-34 is consistent with synchrotron emission from a jet with a break from optically thick to optically thin emission at 1.3-11.0x1013Hz. This is the third time a jet spectral break has been reported for a neutron star X-ray binary. The radio to mm spectral energy distribution of 4U 1820-30 has significant detections at 5 and 300GHz. This confirms the presence of radio emission during a soft state for this neutron star and represents the first detection of mm emission during such a state, unambiguously pointing to the presence of a jet. We also report on three additional unrelated sources - showing mm emission - in the ALMA fields of view of 4U 1728-34 and 4U 1820-30.
Abstract Copyright:
© ESO, 2017
Journal keyword(s):
X-rays: binaries - accretion, accretion disks - stars: individual: 4U 1728-34 - stars: individual: 4U 1820-30 - ISM: jets and outflows - ISM: jets and outflows
Simbad objects:
22
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