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Title: | A Very Young Radio-loud Magnetar | Authors: | Esposito, P. Rea, N. Borghese, A. Zelati, F. Coti Viganò, D. ISRAEL, Gian Luca Tiengo, A. RIDOLFI, ALESSANDRO POSSENTI, ANDREA BURGAY, MARTA Götz, D. Pintore, Fabio STELLA, Luigi Dehman, C. Ronchi, M. CAMPANA, Sergio Garcia-Garcia, A. Graber, V. MEREGHETTI, Sandro Perna, R. Castillo, G. A. Rodríguez Turolla, R. Zane, S. |
Issue Date: | 2020 | Journal: | THE ASTROPHYSICAL JOURNAL LETTERS | Number: | 896 | Issue: | 2 | First Page: | L30 | 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 Lburst ∼ 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 ( NH = (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 E˙rot∼1.4×1036 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. | URI: | http://hdl.handle.net/20.500.12386/29845 | URL: | https://iopscience.iop.org/article/10.3847/2041-8213/ab9742 | ISSN: | 2041-8205 | DOI: | 10.3847/2041-8213/ab9742 | Bibcode ADS: | 2020ApJ...896L..30E | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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File | Description | Size | Format | |
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2004.04083.pdf | postprint | 2.26 MB | Adobe PDF | View/Open |
Esposito_2020_ApJL_896_L30.pdf | Pdf editoriale | 919.99 kB | Adobe PDF | View/Open |
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