Spin-down Evolution and Radio Disappearance of the Magnetar PSR J1622–4950

Abstract

We report on 2.4 yr of radio timing measurements of the magnetar PSRJ1622−4950 using the Parkes Observatory, between 2011 November and 2014 March. During this period the torque on the neutron star (inferred from the rotational frequency derivative) varied greatly, though much less erratically than during the 2 yr following its discovery in 2009. During the last year of our measurements the frequency derivative decreased in magnitude monotonically by 20%, to a value of −1.3×10 −13 s −2 , a factor of 8 smaller than when it was discovered. The flux density continued to vary greatly during our monitoring through 2014 March, reaching a relatively steady low level after late 2012. The pulse profile varied secularly on a similar timescale as the flux density and torque. A relatively rapid transition in all three properties was evident in early 2013. After PSRJ1622−4950 was detected in all of our 87 observations up to 2014 March, we did not detect the magnetar in our resumed monitoring starting in 2015 January and have not detected it in any of the 30 observations conducted through 2016 September.

Spin frequency evolution and pulse profile variations of the recently re-activated radio magnetar XTE J1810–197

“…Instead Archibald et al (2015) report on large ν variations (of factors up to ∼7) starting ∼100 days after the outbursts and continuing for a few hundred days, before ν stabilises again. Similar large ν variations were seen after the 2007 outburst of PSR J1622-4950 (a factor of ∼2 over a few hundred days; Levin et al 2012;Scholz et al 2017), and after the 2003 outburst of XTE J1810-197 as described above. In both Ibrahim et al (2004), circles show values from Camilo et al (2016), the diamond-shaped value is from Pintore et al (2016b) and the square-shaped point is from Pintore et al (2019).…”

Understanding Recent Magnetar Observations from the Magnetospheric Point of View

“…[17] obtained a similar conclusion using a different model for magnetars). The final radio disappearance of these two radio-loud magnetars [9,15] are consistent with the general expectations in the wind braking model.…”

“…While its radio luminosity decrease by factor of ten [15]. Similar radiation and timing behavior is also seen in the third radio-loud magnetar PSR J1622−4950 [9]. For PSR J1622−4950, its spin-down decrease by about a factor of 10.…”

“…For PSR J1622−4950, its spin-down decrease by about a factor of 10. During this process, the radio flux decrease by a factor about 100 [9]. In the wind braking scenario, the spin-down rate is proportional to the square-root of the particle luminosity:Ṗ ∝ L 1/2 p [6].…”

“…Observationally, magnetars have varying spin-down torque [8], or decreasing torque during outburst [9], or increasing torque [10]. Their spectra also contain a significant fraction of nonthermal emissions [11,12].…”