Identification of the infrared counterpart of SGR 1935+2154 with the Hubble Space Telescope

Abstract

We present deep Hubble Space Telescope observations of a new magnetar source, the soft gamma-repeater SGR 1935+2154, discovered by Swift. We obtained three epochs of observations: while the source was active in March 2015, during a quiescent period in August 2015, and during a further active phase in May 2016. Close to the center of the X-ray error region identified by Chandra we find a faint (F140W(AB)=25.3) source, which fades by a factor of ~2 over the course of 5 months between the first two epochs of observations, before rebrightening during the second active period. If this source is indeed the counterpart to SGR 1935+2154 then it is amongst the faintest yet located for a magnetar. Our observations are spaced over 1.3 years and enable us to place limits on the source velocity of $\mu =(60\pm 40)$ km s${}^{-1}$ kpc${}^{-1}$; observations on timescales of a decade can hence probe proper motion limits smaller than the velocities observed for the majority of pulsars. The comparison of the optical/IR and X-ray lightcurves of the source suggests that emission in the two regimes is associated but not directly correlated, offering support for a magnetospheric versus a fallback disc origin.

7 pages, 3 figures, accepted for publication in ApJ

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Cited by in corpus (12)

• INTEGRAL discovery of a burst with associated radio emission from the magnetar SGR 1935+2154
• A Magnetar-Asteroid Impact Model for FRB 200428 Associated with an X-ray Burst from SGR 1935+2154
• Multi-frequency observations of SGR J1935+2154
• Where are the magnetar binary companions? Candidates from a comparison with binary population synthesis predictions
• Constraining the X-ray - Infrared spectral index of second-timescale flares from SGR1935+2154 with Palomar Gattini-IR
• Possible Periodic Windowed Behavior in SGR1935+2154 SGR Bursts
• New candidates for magnetar counterparts from a deep search with the Hubble Space Telescope
• Testing afterglow models of FRB 200428 with early post-burst observations of SGR 1935+2154
• The infrared counterpart and proper motion of magnetar SGR0501+4516
• Deep upper limit on the optical emission during a hard X-ray burst from the magnetar SGR J1935+2154
• The Fast Radio Burst-emitting magnetar SGR 1935+2154 -- proper motion and variability from long-term Hubble Space Telescope monitoring
• A Variable X-ray Source Close to the Magnetar SGR 1935+2154