| タイトル | X-ray Follow-ups of XSS J12270-4859: A Low-mass X-ray Binary with Gamma-ray Fermi-LAT Association |
| 本文（外部サイト） | http://hdl.handle.net/2060/20140002696 |
| 著者（英） | Motta, S.; Belloni, T.; deMartino, D.; Pellizzoni, A.; Piano, G.; Falanga, M.; Masetti, N.; Possenti, A.; Papitto, A.; Mukai, K.; Evangelista, Y.; Mouchet, M. |
| 著者所属（英） | Osservatorio Astronomico, Capodimonte |
| 発行日 | 2013-02-01 |
| 言語 | eng |
| 内容記述 | Context. XSS J1227.0-4859 is a peculiar, hard X-ray source recently positionally associated to the Fermi-LAT source 1FGL J1227.9- 4852/2FGL J1227.7-4853. Multi-wavelength observations have added information on this source, indicating a low-luminosity lowmass X-ray binary (LMXB), but its nature is still unclear. Aims. To progress in our understanding, we present new X-ray data from a monitoring campaign performed in 2011 with the XMM-Newton, RXTE, and Swift satellites and combine them with new gamma-ray data from the Fermi and AGILE satellites. We complement the study with simultaneous near-UV photometry from XMM-Newton and with previous UV/optical and near-IR data. Methods. We analysed the temporal characteristics in the X-rays, near-UV, and gamma rays and studied the broad-band spectral energy distribution from radio to gamma rays. Results. The X-ray history of XSS J1227 over 7 yr shows a persistent and rather stable low-luminosity (6 1033 d2 1 kpcerg s1) source, with flares and dips being peculiar and permanent characteristics. The associated Fermi-LAT source 2FGL J1227.7-4853 is also stable over an overlapping period of 4.7 yr. Searches for X-ray fast pulsations down to msec give upper limits to pulse fractional amplitudes of 1525% that do not rule out a fast spinning pulsar. The combined UV/optical/near-IR spectrum reveals a hot component at approximately 13 kK and a cool one at approximately 4.6 kK. The latter would suggest a late-type K2K5 companion star, a distance range of 1.43.6 kpc, and an orbital period of 7-9 h. A near-UV variability (6 h) also suggests a longer orbital period than previously estimated. Conclusions. The analysis shows that the X-ray and UV/optical/near-IR emissions are more compatible with an accretion-powered compact object than with a rotational powered pulsar. The X-ray to UV bolometric luminosity ratio could be consistent with a binary hosting a neutron star, but the uncertainties in the radio data may also allow an LMXB black hole with a compact jet. In this case, it would be the first associated with a high-energy gamma-ray source. |
| NASA分類 | Astronomy |
| レポートNO | GSFC-E-DAA-TN8686 |
| 権利 | Copyright, Distribution under U.S. Government purpose rights |
|
