Esposito, P;
Rea, N;
Borghese, A;
Zelati, FC;
Vigano, D;
Israel, GL;
Tiengo, A;
... Zane, S; + view all
(2020)
A Very Young Radio-loud Magnetar.
The Astrophysical Journal Letters
, 896
(2)
, Article L30. 10.3847/2041-8213/ab9742.
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Abstract
The magnetar Swift J1818.0–1607 was discovered in 2020 March when Swift detected a 9 ms hard X-ray burst and a long-lived outburst. Prompt X-ray observations revealed a spin period of 1.36 s, soon confirmed by the discovery of radio pulsations. We report here on the analysis of the Swift burst and follow-up X-ray and radio observations. The burst average luminosity was L burst ~ 2 × 1039 erg s−1 (at 4.8 kpc). Simultaneous observations with XMM-Newton and NuSTAR three days after the burst provided a source spectrum well fit by an absorbed blackbody (${N}_{{\rm{H}}}$ = (1.13 ± 0.03) × 1023 cm−2 and kT = 1.16 ± 0.03 keV) plus a power law (Γ = 0.0 ± 1.3) in the 1–20 keV band, with a luminosity of ~8 × 1034 erg s−1, dominated by the blackbody emission. From our timing analysis, we derive a dipolar magnetic field B ~ 7 × 1014 G, spin-down luminosity ${\dot{E}}_{\mathrm{rot}}\sim 1.4\times {10}^{36}$ erg s−1, and characteristic age of 240 yr, the shortest currently known. Archival observations led to an upper limit on the quiescent luminosity <5.5 × 1033 erg s−1, lower than the value expected from magnetar cooling models at the source characteristic age. A 1 hr radio observation with the Sardinia Radio Telescope taken about 1 week after the X-ray burst detected a number of strong and short radio pulses at 1.5 GHz, in addition to regular pulsed emission; they were emitted at an average rate 0.9 min−1 and accounted for ~50% of the total pulsed radio fluence. We conclude that Swift J1818.0–1607 is a peculiar magnetar belonging to the small, diverse group of young neutron stars with properties straddling those of rotationally and magnetically powered pulsars. Future observations will make a better estimation of the age possible by measuring the spin-down rate in quiescence.
| Type: | Article |
|---|---|
| Title: | A Very Young Radio-loud Magnetar |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/2041-8213/ab9742 |
| Publisher version: | https://doi.org/10.3847/2041-8213/ab9742 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Magnetars; Neutron stars; Transient sources; X-ray bursts; Radio pulsars |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10101882 |
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