GROJ1750-27: a neutron star far behind the Galactic Center switching into the propeller regime

Abstract

We report on analysis of properties of the X-ray binary pulsar GROJ1750-27 based on X-ray (Chandra, Swift, and Fermi/GBM), and near-infrared (VVV and UKIDSS surveys) observations. An accurate position of the source is determined for the first time and used to identify its infrared counterpart. Based on the VVV data we investigate the spectral energy distribution (SED) of the companion, taking into account a non-standard absorption law in the source direction. A comparison of this SED with those of known Be/X-ray binaries and early type stars has allowed us to estimate a lower distance limit to the source at $>12$ kpc. An analysis of the observed spin-up torque during a giant outburst in 2015 provides an independent distance estimate of $14-22$ kpc, and also allows to estimate the magnetic field on the surface of the neutron star at $B\simeq (3.5-4.5)\times 10^{12}$ G. The latter value is in agreement with the possible transition to the propeller regime, a strong hint for which was revealed by Swift/XRT and Chandra. We conclude that GROJ1750-27 is located far behind the Galactic Center, which makes it one of the furthest Galactic X-ray binaries known.

8 pages, 7 figures, accepted for publication in MNRAS

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• GASS: The Parkes Galactic All-Sky Survey. Update: improved correction for instrumental effects and new data release
• Extinction ratios in the inner Galaxy as revealed by the VVV survey
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Cited by in corpus (7)

• SRG/ART-XC and NuSTAR observations of the X-ray pulsar GRO J1008-57 in the lowest luminosity state
• Catalog of the Galactic population of X-ray pulsars in High-mass X-ray binary systems
• First characterization of Swift J1845.7-0037 with NuSTAR
• Discovery of cyclotron and narrow Fe K${}_{\alpha }$ lines in HMXB GRO J1750-27
• The unaltered pulsar: GRO J1750-27, a super-critical X-ray neutron star that does not blink an eye
• NuSTAR discovery of a cyclotron line in GRO J1750-27
• Monte-Carlo simulations on possible collimation effects of outflows to fan-beamed emission of ultraluminous accreting X-ray pulsars