X-ray outburst of XMMU J004855.5-734946: confirmation as a Be/X-ray binary pulsar
ATel #9229; G. Vasilopoulos (MPE Garching), F. Haberl (MPE Garching), V. Antoniou (SAO), A. Zezas (UoC/IESL, SAO)
on 10 Jul 2016; 08:58 UT
Credential Certification: Georgios Vasilopoulos (gevas@mpe.mpg.de)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
XMMU J004855.5-734946 is a candidate BeXRB system in the Small Magellanic Cloud (SMC, Haberl & Sturm 2016, A&A, 586, 81).
The system was detected in a recent 45 s Swift/XRT observation on 2016-06-24 as part of a routine Swift/XRT survey of the SMC (ATel #9197).
Following the new X-ray detection of the system we requested Swift/XRT monitoring of the source to confirm its luminosity level and follow the X-ray outburst.
Moreover, we requested a Chandra DDT ToO to obtain a clean spectrum of the source and search for pulsations.
The Chandra ToO (2016-07-06; ObsID 18885) revealed a spin period of 15.639±0.005 s, thus making XMMU J004855.5-734946 the 64th known high mass X-ray binary pulsar in the SMC.
Its X-ray spectrum is well fitted by an absorbed power-law model with photon index of 0.6 and a total absorption of 6.7⋅1020 cm-2, resulting in an absorbed X-ray flux of 8.5⋅10-12 erg cm-2 s-1 (0.3-10 keV).
By using these best fit values we convert the Swift count rates to fluxes. These are presented in the table below.
Detailed results from the Chandra and Swift data will be presented in Vasilopoulos et al. (2016, in prep).
We thank the Swift team for accepting and scheduling the target of opportunity observations.
We thank the Chandra Director for accepting our DDT request and the CXC team for promptly scheduling the observations.
Swift XRT monitoring:
Date XRT count rate luminosity (0.3-10 keV, 65 kpc)
[counts s-1] [1036 erg s-1]
2016-06-16 0.08±0.03 c/sec 3.7±1.4
2016-06-24 0.18±0.05 c/sec 8.3±2.3
2016-06-29 0.18±0.02 c/sec 8.3±0.9
2016-07-01 0.22±0.03 c/sec 10.2±1.4
2016-07-03 0.14±0.03 c/sec 6.5±1.4
2016-07-05 0.12±0.02 c/sec 5.5±0.9
2016-07-08 0.06±0.01 c/sec 3.0±0.6
