Revival of the Magnetar PSR J1622–4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

Abstract

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622–4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100× larger than during its dormant state. The X-ray flux one month after reactivation was at least 800× larger than during quiescence, and has been decaying exponentially on a 111 ± 19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3–6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6–8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.

Two New Outbursts and Transient Hard X-Rays from 1E 1048.1-5937

“…While the repetition, and monotonic decline in amplitude, of the torque variations from 1E 1048.1−5937 are striking and unique, rapid, extreme variability in the torque (ν) evolution appears to be a common feature following magnetar outbursts. In addition to that observed now repeatedly in 1E 1048.1−5937, similar variations have been observed in 1E 1547−5408 (Dib et al 2012), PSR J1622−4950 Camilo et al 2018), and in XTE 1810−197 (Camilo et al 2016. Thus, in a large fraction of magnetar outbursts for which the spin-down rate has been tracked for over a decade, these extreme torque variations are observed, and can dominate the long-term spin evolution of these sources.…”

The Thousand-Pulsar-Array programme on MeerKAT – I. Science objectives and first results

“…High-energy observations can, for example, provide independent constraints on the pulsar geometry, either through the analysis of their multiwavelength pulse profiles (Pierbattista et al 2015;Giraud & Pétri 2019) or pulsar wind nebulae (Ng & Romani 2004;Klingler et al 2018;Barkov et al 2019). Multiwavelength monitoring of unusual pulsars such as the radio-loud magnetars and transition objects can shed light onto potential magnetospheric differences between the diverse neutron star populations (Camilo et al 2018;Dai et al 2018). Finally, the radio-X-ray correlation in mode-switching pulsars can put models of the pulsar magnetosphere to the test (Hermsen et al 2013;Rigoselli et al 2019).…”

A spectroscopic, photometric, polarimetric, and radio study of the eclipsing polar UZ Fornacis: the first simultaneous SALT and MeerKAT observations

“…Observations of UZ For and the surrounding field were taken on 2018 November 6 (MJD 58428) using the MeerKAT radio telescope (Camilo et al 2018;Jonas & MeerKAT Team 2016 bandwidth of 856 MHz split into 4096 channels. Observations started at 20:06:17.7 (Universal Time Central, utc) and finished at 21:59:58.9 (utc), overlapping with both the photometric and spectropolarimetric observation taken in Sutherland.…”