The X-ray outburst of the Galactic Center magnetar over six years of Chandra observations

Abstract

The magnetar SGR J1745-2900 discovered at parsecs distance from the Milky Way central black hole, Sagittarius A*, represents the closest pulsar to a supermassive black hole ever detected. Furthermore, its intriguing radio emission has been used to study the environment of the black hole, as well as to derive a precise position and proper motion for this object. The discovery of SGR J1745-2900 has opened interesting debates about the number, age and nature of pulsars expected in the Galactic center region. In this work, we present extensive X-ray monitoring of the outburst of SGR J1745-2900 using the Chandra X-ray Observatory, the only instrument with the spatial resolution to distinguish the magnetar from the supermassive black hole (2.4" angular distance). It was monitored from its outburst onset in April 2013 until August 2019, collecting more than fifty Chandra observations for a total of more than 2.3 Ms of data. Soon after the outburst onset, the magnetar emission settled onto a purely thermal emission state that cooled from a temperature of about 0.9 to 0.6 keV over 6 years. The pulsar timing properties showed at least two changes in the period derivative, increasing by a factor of about 4 during the outburst decay. We find that the long-term properties of this outburst challenge current models for the magnetar outbursts.

11 pages, 6 figures. Accepted by ApJ

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Cited by in corpus (8)

• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• Detection of a dense group of hyper-compact radio sources in the central parsec of the Galaxy
• Iron K-alpha echoes from the circumnuclear disk orbiting Sgr A*
• Magnetar Outburst Models with Cooling Simulations
• High Energy Emission from the Galactic Center
• Phase-Resolved Spectroscopy of the Magnetar SGR J1745-2900 Based on Data from the NuSTAR Observatory
• A magnetar outburst with atypical evolution: the case of Swift J1555.2-5402
• A month of monitoring the new magnetar Swift J1555.2-5402 during an X-ray outburst