TY - JOUR
T1 - Disc-jet coupling in the Terzan 5 neutron star X-ray binary EXO 1745-248
AU - Tetarenko, A. J.
AU - Bahramian, A.
AU - Sivakoff, G. R.
AU - Tremou, E.
AU - Linares, M.
AU - Tudor, V.
AU - Miller-Jones, J. C.A.
AU - Heinke, C. O.
AU - Chomiuk, L.
AU - Strader, J.
AU - Altamirano, D.
AU - Degenaar, N.
AU - Maccarone, T.
AU - Patruno, A.
AU - Sanna, A.
AU - Wijnands, R.
N1 - Funding Information:
AJT would like to thank Erik Rosolowsky for helpful discussions regarding MCMC implementation. AJT, GRS, and COH are supported by NSERC Discovery Grants. JCAMJ is the recipient of an Australian Research Council Future Fellowship (FT140101082). ML was supported by the Spanish Ministry of Economy and Competitiveness under the grant AYA2013-42627. ET acknowledges support from NSF grant AST-1412549. JS acknowledges support via NSF grant AST-1308124. ND acknowledges support via an NWO/Vidi grant and an EU Marie Curie Intra-European fellowship under contract no. FP-PEOPLE-2013-IEF-627148. DA acknowledges support from the Royal Society. AP acknowledges support from an NWO Vidi fellowship. RW is supported by an NWO Top Grant, Module 1. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research has made use of the following data and software packages: Swift BAT transient monitor results provided by the Swift BAT team, and the Swift XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. We acknowledge extensive use of the ADS and arXiv.
Publisher Copyright:
© 2016 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society.
PY - 2016/7/21
Y1 - 2016/7/21
N2 - We present the results of Very Large Array, Australia Telescope Compact Array, and Swift X-ray Telescope observations of the 2015 outburst of the transient neutron star X-ray binary (NSXB), EXO 1745-248, located in the globular cluster Terzan 5. Combining (near-) simultaneous radio and X-ray measurements, we measure a correlation between the radio and X-ray luminosities of LR ∝ LßX with ß = 1.68+0.10-0.09, linking the accretion flow (probed by X-ray luminosity) and the compact jet (probed by radio luminosity). While such a relationship has been studied in multiple black hole X-ray binaries (BHXBs), this work marks only the third NSXB with such a measurement. Constraints on this relationship in NSXBs are strongly needed, as comparing this correlation between different classes of XB systems is key in understanding the properties that affect the jet production process in accreting objects. Our best-fitting disc-jet coupling index for EXO 1745-248 is consistent with the measured correlation in NSXB 4U 1728-34 (ß = 1.5 ± 0.2) but inconsistent with the correlation we fit using the most recent measurements from the literature of NSXB Aql X-1 (ß = 0.76+0.14-0.15). While a similar disc-jet coupling index appears to hold across multiple BHXBs in the hard accretion state, this does not appear to be the case with the three NSXBs measured so far. Additionally, the normalization of the EXO 1745-248 correlation is lower than the other two NSXBs, making it one of the most radio faint XBs ever detected in the hard state. We also report the detection of a type-I X-ray burst during this outburst, where the decay time-scale is consistent with hydrogen burning.
AB - We present the results of Very Large Array, Australia Telescope Compact Array, and Swift X-ray Telescope observations of the 2015 outburst of the transient neutron star X-ray binary (NSXB), EXO 1745-248, located in the globular cluster Terzan 5. Combining (near-) simultaneous radio and X-ray measurements, we measure a correlation between the radio and X-ray luminosities of LR ∝ LßX with ß = 1.68+0.10-0.09, linking the accretion flow (probed by X-ray luminosity) and the compact jet (probed by radio luminosity). While such a relationship has been studied in multiple black hole X-ray binaries (BHXBs), this work marks only the third NSXB with such a measurement. Constraints on this relationship in NSXBs are strongly needed, as comparing this correlation between different classes of XB systems is key in understanding the properties that affect the jet production process in accreting objects. Our best-fitting disc-jet coupling index for EXO 1745-248 is consistent with the measured correlation in NSXB 4U 1728-34 (ß = 1.5 ± 0.2) but inconsistent with the correlation we fit using the most recent measurements from the literature of NSXB Aql X-1 (ß = 0.76+0.14-0.15). While a similar disc-jet coupling index appears to hold across multiple BHXBs in the hard accretion state, this does not appear to be the case with the three NSXBs measured so far. Additionally, the normalization of the EXO 1745-248 correlation is lower than the other two NSXBs, making it one of the most radio faint XBs ever detected in the hard state. We also report the detection of a type-I X-ray burst during this outburst, where the decay time-scale is consistent with hydrogen burning.
KW - Globular clusters: individual: Terzan 5
KW - ISM: jets and outflows
KW - Radio continuum: stars
KW - Stars: individual: EXO 1745-248
KW - Stars: neutron
KW - X-rays: binaries
UR - http://www.scopus.com/inward/record.url?scp=84979019863&partnerID=8YFLogxK
U2 - 10.1093/mnras/stw1013
DO - 10.1093/mnras/stw1013
M3 - Article
AN - SCOPUS:84979019863
SN - 0035-8711
VL - 460
SP - 345
EP - 355
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -