The X-Ray Reactivation of the Radio Bursting Magnetar SGR J1935+2154

Borghese, A.A.BorgheseCoti Zelati, F.F.Coti ZelatiRea, N.N.ReaEsposito, P.P.EspositoISRAEL, Gian LucaGian LucaISRAELMEREGHETTI, SandroSandroMEREGHETTITiengo, A.A.Tiengo2025-03-032025-03-0320202041-8205http://hdl.handle.net/20.500.12386/36348A few years after its discovery as a magnetar, SGR J1935+2154 started a new burst-active phase on 2020 April 27, accompanied by a large enhancement of its X-ray persistent emission. Radio single bursts were detected during this activation, strengthening the connection between magnetars and fast radio bursts. We report on the X-ray monitoring of SGR J1935+2154 from ∼3 days prior to ∼3 weeks after its reactivation, using Swift, the Nuclear Spectroscopic Telescope Array (NuSTAR), and the Neutron Star Interior Composition Explorer (NICER). We detected X-ray pulsations in the NICER and NuSTAR observations, and constrained the spin period derivative to $| \dot{P}| \lt 3\times {10}^{-11}$ s s-1 (3σ c.l.). The pulse profile showed a variable shape switching between single and double-peaked as a function of time and energy. The pulsed fraction decreased from ∼34% to ∼11% (5-10 keV) over ∼10 days. The X-ray spectrum was well fit by an absorbed blackbody model with temperature decreasing from kTBB ∼ 1.6 to 0.45-0.6 keV, plus a nonthermal power-law component (Γ ∼ 1.2) observed up to ∼25 keV with NuSTAR. The 0.3-10 keV X-ray luminosity increased in less than 4 days from $\sim 6\times {10}^{33}{d}_{6.6}^{2}$ erg s-1 to about $3\times {10}^{35}{d}_{6.6}^{2}$ erg s-1 and then decreased again to $2.5\times {10}^{34}{d}_{6.6}^{2}$ erg s-1 over the following 3 weeks of the outburst, where d6.6 is the source distance in units of 6.6 kpc. We also detected several X-ray bursts, with properties typical of short magnetar bursts.STAMPAenThe X-Ray Reactivation of the Radio Bursting Magnetar SGR J1935+2154Article10.3847/2041-8213/aba82a2-s2.0-85093121263https://api.elsevier.com/content/abstract/scopus_id/85093121263https://iopscience.iop.org/article/10.3847/2041-8213/aba82a2020ApJ...902L...2BFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation