Coti Zelati, F.F.Coti ZelatiBorghese, A.A.BorgheseISRAEL, Gian LucaGian LucaISRAELRea, N.N.ReaEsposito, P.P.EspositoPILIA, MauraMauraPILIABURGAY, MARTAMARTABURGAYPOSSENTI, ANDREAANDREAPOSSENTICORONGIU, ALESSANDROALESSANDROCORONGIURIDOLFI, ALESSANDROALESSANDRORIDOLFIDehman, C.C.DehmanViganò, D.D.ViganòTurolla, R.R.TurollaZane, S.S.ZaneTiengo, A.A.TiengoKeane, E. F.E. F.Keane2022-03-242022-03-2420212041-8205http://hdl.handle.net/20.500.12386/31865The 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<SUP>-9</SUP> erg cm<SUP>-2</SUP> (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<SUP>-11</SUP> to ∼2.5 × 10<SUP>-11</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP> one month later (0.3-10 keV). Based on our timing analysis, we estimate a dipolar magnetic field ≍5.5 × 10<SUP>14</SUP> G at pole, a spin-down luminosity ≍2.4 × 10<SUP>32</SUP> erg s<SUP>-1</SUP>, 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, ∼10<SUP>15</SUP> G.STAMPAenArticle10.3847/2041-8213/abda522-s2.0-85100771764https://iopscience.iop.org/article/10.3847/2041-8213/abda52https://api.elsevier.com/content/abstract/scopus_id/851007717642021ApJ...907L..34CFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering