Multi-wavelength study of the first γ-ray emitting LMXB XSS J12270-4859

Abstract

A multiwavelength strategy for identifying celestial γ-ray sources AIP Conf.Abstract. Fermi is discovering many new γ-ray sources, and 1FGL J1227.9-4852 is one of them. Recent studies suggest that this source is associated with the X-ray source XSS J12270-4859 (hereafter J12270), of which nature is poorly understood. In this paper, we show results of our Suzaku and RXTE X-ray observations which are partly simultaneous with near-infrared (NIR) observations using InfraRed Survey Facility (IRSF). We found that J12270 shows (1) no emission lines in the X-ray spectra, (2) unique rapid temporal variations in X-rays, and (3) almost simultaneous X-ray and NIR flares. To investigate its nature, we constructed a spectral energy distribution (SED) from radio to γ-rays. Because of the similarity of its SED with those of other microquasars, we propose that J12270 is a microquasar with a synchrotron jet, and also the first γ-ray emitting low-mass X-ray binary.

Unveiling the redback nature of the low-mass X-ray binary XSS J1227.0−4859 through optical observations★

“…The nIR IRSF photometry gives the source at: J=15.39(8), H=15.08(8) and Ks=14.9(2) consistent with the measures in 2009 reported by dM10 and by Saitou et al (2011). The light curves, though with lower temporal resolution, display the same variability seen in the U band (Fig.…”

“…Surprisingly we also found XSS J1227 to be positionally coincident with the high energy gamma-ray Fermi -LAT source 1FGL J1227.9-4852/2FGL J1227.7-4853 emitting up to 10 GeV (dM10). Multi-wavelength follow-up observations, performed by Hill et al (2011), Saitou et al (2011) andde Martino et al (2013a, henceforth dM13), showed persistent X-ray and high energy gamma-ray emissions over an interval of at least ∼ 7 yr, making it an unique case among known galactic binaries with comparable X-ray and gammaray luminosities. The detection of a radio (Hill et al 2011) and gamma-ray (dM10) counterpart, together with a putative 4.5 h orbital period (dM10), led to the suggestion that XSS J1227 could host a MSP (Hill et al 2011), sharing similar properties with PSR J1023+0038 (Wang et al 2009;Tam et al 2010;Archibald et al 2010).…”