The bright unidentifiedγ-ray source 1FGL J1227.9−4852: can it be associated with a low-mass X-ray binary?

Abstract

We present an analysis of high energy (HE; 0.1–300 GeV) γ‐ray observations of 1FGL J1227.9−4852 with the Fermi Gamma‐ray Space Telescope, follow‐up radio observations with the Australia Telescope Compact Array, Giant Metrewave Radio Telescope and Parkes radio telescopes of the same field and follow‐up optical observations with the ESO VLT. We also examine archival XMM–Newton and INTEGRAL X‐ray observations of the region around this source. The γ‐ray spectrum of 1FGL J1227.9−4852 is best fitted with an exponentially cut‐off power law, reminiscent of the population of pulsars observed by Fermi. A previously unknown, compact radio source within the 99.7 per cent error circle of 1FGL J1227.9−4852 is discovered and has a morphology consistent either with an AGN core/jet structure or with two roughly symmetric lobes of a distant radio galaxy. A single bright X‐ray source XSS J12270−4859, a low‐mass X‐ray binary, also lies within the 1FGL J1227.9−4852 error circle and we report the first detection of radio emission from this source. The potential association of 1FGL J1227.9−4852 with each of these counterparts is discussed. Based upon the available data we find the association of the γ‐ray source to the compact double radio source unlikely and suggest that XSS J12270−4859 is a more likely counterpart to the new HE source. We propose that XSS J12270−4859 may be a millisecond binary pulsar and draw comparisons with PSR J1023+0038.

Different twins in the millisecond pulsar recycling scenario: Optical polarimetry of PSR J1023+0038 and XSS J12270-4859

“…This variability reinforced the prediction, first made by Hill et al (2011), that the system could harbour an active radio MSP, sharing similar properties with J1023. Follow-up observations in the radio finally succeeded in detecting pulsations at a period of 1.69 ms (Roy et al 2014).…”

“…Subsequent independent multi-wavelength studies (Pretorius 2009;Saitou et al 2009;de Martino et al 2010de Martino et al , 2013Hill et al 2011; casted doubts on this classification, suggesting instead an identification as a LMXB showing unusual dipping and flaring behaviour on timescales of few hundreds of seconds. XSS J12270−4859 was subsequently recognised to be spatially coincident with a moderately bright gamma-ray source that was detected by Fermi-LAT emitting up to 10 GeV (de Martino et al 2010;Hill et al 2011), and is now known as 3FGL J1227.9−4854.…”

The counterpart/s of IGR J20159+3713/SWIFT J2015.9+3715: dissecting a complex region with emission from keV to TeV

“…This object has also been detected at hard X-ray energies by INTEGRAL/IBIS and Swift/BAT, it has then be classified as a CV of the magnetic type (Masetti et al 2006) and subsequently it was associated with a Fermi source (1FGL J1227.9−4852/2FGL J1227.7−4853) listed in the first and second catalogues (Abdo et al 2010(Abdo et al , 2012; only recently, it was described as a peculiar type of X-ray binary (De Martino et al 2010Hill et al 2011). Furthermore, XSS J12270−4859 is not the first time that a CV has been associated with a GeV emitter.…”

Large-scale flow dynamics and radiation in pulsarγ-ray binaries

“…The number of members of the class of gamma-ray binaries is growing, being at present around ten, including unconfirmed candidates (e.g. Albert et al 2006Albert et al , 2007Aharonian et al 2005a,b;Abdo et al 2009aAbdo et al ,b,c, 2010aAbdo et al ,b, 2011Tavani et al 2009a,b;Sabatini et al 2010;Williams et al 2010;Tam et al 2010;Hill et al 2011;Falcone et al 2011;Corbet et al 2011).…”