The New Magnetar SGR J1830-0645 in Outburst
Date Issued
2021
Author(s)
Coti Zelati, F.
•
Borghese, A.
•
•
Rea, N.
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Esposito, P.
•
•
•
•
•
•
Dehman, C.
•
Viganò, D.
•
Turolla, R.
•
Zane, S.
•
Tiengo, A.
•
Keane, E. F.
Abstract
The detection of a short hard X-ray burst and an associated bright soft X-ray source by the Swift satellite in 2020 October heralded a new magnetar in outburst, SGR J1830-0645. Pulsations at a period of ∼10.4 s were detected in prompt follow-up X-ray observations. We present here the analysis of the Swift/Burst Alert Telescope burst, of XMM-Newton and the Nuclear Spectroscopic Telescope Array observations performed at the outburst peak, and of a Swift/X-ray Telescope monitoring campaign over the subsequent month. The burst was single-peaked, lasted ∼6 ms, and released a fluence of ≍5 × 10-9 erg cm-2 (15-50 keV). The spectrum of the X-ray source at the outburst peak was well described by an absorbed double-blackbody model plus a power-law component detectable up to ∼25 keV. The unabsorbed X-ray flux decreased from ∼5 × 10-11 to ∼2.5 × 10-11 erg cm-2 s-1 one month later (0.3-10 keV). Based on our timing analysis, we estimate a dipolar magnetic field ≍5.5 × 1014 G at pole, a spin-down luminosity ≍2.4 × 1032 erg s-1, and a characteristic age ≍24 kyr. The spin modulation pattern appears highly pulsed in the soft X-ray band, and becomes smoother at higher energies. Several short X-ray bursts were detected during our campaign. No evidence for periodic or single-pulse emission was found at radio frequencies in observations performed with the Sardinia Radio Telescope and Parkes. According to magneto-thermal evolutionary models, the real age of SGR J1830-0645 is close to the characteristic age, and the dipolar magnetic field at birth was slightly larger, ∼1015 G.
Volume
907
Issue
2
Start page
L34
Issn Identifier
2041-8205
Ads BibCode
2021ApJ...907L..34C
Rights
open.access
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