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Title: 3XMM J185246.6+003317: ANOTHER LOW MAGNETIC FIELD MAGNETAR

We study the outburst of the newly discovered X-ray transient 3XMM J185246.6+003317, re-analyzing all available XMM-Newton observations of the source to perform a phase-coherent timing analysis, and derive updated values of the period and period derivative. We find the source rotating at P = 11.55871346(6) s (90% confidence level; at epoch MJD 54728.7) but no evidence for a period derivative in the seven months of outburst decay spanned by the observations. This translates to a 3σ upper limit for the period derivative of P-dot <1.4×10{sup −13} s s{sup –1}, which, assuming the classical magneto-dipolar braking model, gives a limit on the dipolar magnetic field of B {sub dip} < 4.1 × 10{sup 13} G. The X-ray outburst and spectral characteristics of 3XMM J185246.6+003317 confirm its identification as a magnetar, but the magnetic field upper limit we derive defines it as the third ''low-B'' magnetar discovered in the past 3 yr, after SGR 0418+5729 and Swift J1822.3–1606. We have also obtained an upper limit to the quiescent luminosity (<4 × 10{sup 33} erg s{sup –1}), in line with the expectations for an old magnetar. The discovery of this new low field magnetar reaffirms the prediction of about one outburst per year from the hidden population of aged magnetars.
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Institute of Space Sciences (CSIC-IEEC), Campus UAB, Torre C5, 2a planta, E-08193 Barcelona (Spain)
  2. INAF-Astronomical Observatory of Rome, via Frascati 33, I-00040, Monte Porzio Catone, Roma (Italy)
  3. Departament de Fisica Aplicada, Universitat d'Alacant, Ap. Correus 99, E-03080 Alacant (Spain)
Publication Date:
OSTI Identifier:
22364028
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 781; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC X-RAY SOURCES; LUMINOSITY; MAGNETIC FIELDS; MAGNETIC STARS; PULSARS; TRANSIENTS; X RADIATION