X-ray softening in the new X-ray transient XTE J1719-291 during its 2008 outburst decay

M. Armas Padilla, N. Degenaar, A. Patruno, D. M. Russell, M. Linares, T. J. Maccarone, J. Homan, R. Wijnands

Research output: Contribution to journalArticlepeer-review

Abstract

The X-ray transient XTE J1719-291 was discovered with Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) during its outburst in 2008 March, which lasted at least 46d. Its 2-10keV peak luminosity is 7 × 10 35ergs -1 assuming a distance of 8kpc, which classifies the system as a very faint X-ray transient. The outburst was monitored with Swift, RXTE, Chandra and XMM-Newton. We analysed the X-ray spectral evolution during the outburst. We fitted the overall data with a simple power-law model corrected for absorption and found that the spectrum softened with decreasing luminosity. However, the XMM-Newton spectrum cannot be fitted with a simple one-component model, but it can be fitted with a thermal component (blackbody or disc blackbody) plus a power-law model affected by absorption. Therefore, the softening of the X-ray spectrum with decreasing X-ray luminosity might be due to a change in photon index or alternatively it might be due to a change in the properties of the soft component. Assuming that the system is an X-ray binary, we estimated a long-term time-averaged mass accretion rate of ∼ 7.7 × 10 -13M yr -1 for a neutron star as a compact object and ∼ 3.7 × 10 -13M yr -1 in the case of a black hole. Although no conclusive evidence is available about the nature of the accretor, based on the X-ray/optical luminosity ratio we tentatively suggest that a neutron star is present in this system.

Original languageEnglish (US)
Pages (from-to)659-665
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume417
Issue number1
DOIs
StatePublished - Oct 2011

Keywords

  • Accretion, accretion discs
  • Stars: individual: XTE J1719-291
  • X-rays: binaries

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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