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NuSTAR Discovery of a 3.76 s Transient Magnetar Near Sagittarius A*

Mori, Kaya and Gotthelf, Eric V. and Zhang, Shou and An, Hongjun and Baganoff, Frederick K. and Barrière, Nicolas M. and Beloborodov, Andrei M. and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Dufour, Francois and Grefenstette, Brian W. and Hailey, Charles J. and Harrison, Fiona A. and Hong, Jaesub and Kaspi, Victoria M. and Kennea, Jamie A. and Madsen, Kristin K. and Markwardt, Craig B. and Nynka, Melania and Stern, Daniel and Tomsick, John A. and Zhang, William W. (2013) NuSTAR Discovery of a 3.76 s Transient Magnetar Near Sagittarius A*. Astrophysical Journal Letters, 770 (2). Art. No. L23. ISSN 2041-8205.

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We report the discovery of 3.76 s pulsations from a new burst source near Sgr A^* observed by the NuSTAR observatory. The strong signal from SGR J1745–29 presents a complex pulse profile modulated with pulsed fraction 27% ± 3% in the 3-10 keV band. Two observations spaced nine days apart yield a spin-down rate of Ṗ =(6.5 ± 1.4) × 10^(–12). This implies a magnetic field B = 1.6 × 10^(14) G, spin-down power Ė =5 × 10^(33) erg s^(–1), and characteristic age P/2Ṗ =9 × 10^3 yr for the rotating dipole model. However, the current Ṗ may be erratic, especially during outburst. The flux and modulation remained steady during the observations and the 3-79 keV spectrum is well fitted by a combined blackbody plus power-law model with temperature kT_(BB) = 0.96 ± 0.02 keV and photon index Γ = 1.5 ± 0.4. The neutral hydrogen column density (N_H ~ 1.4 × 10^(23) cm^(–2)) measured by NuSTAR and Swift suggests that SGR J1745–29 is located at or near the Galactic center. The lack of an X-ray counterpart in the published Chandra survey catalog sets a quiescent 2-8 keV luminosity limit of L_x ≾ 10^(32) erg s^(–1). The bursting, timing, and spectral properties indicate a transient magnetar undergoing an outburst with 2-79 keV luminosity up to 3.5 × 10^(35) erg s^(–1) for a distance of 8 kpc. SGR J1745–29 joins a growing subclass of transient magnetars, indicating that many magnetars in quiescence remain undetected in the X-ray band or have been detected as high-B radio pulsars. The peculiar location of SGR J1745–29 has important implications for the formation and dynamics of neutron stars in the Galactic center region.

Item Type:Article
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URLURL TypeDescription Paper
Mori, Kaya0000-0002-9709-5389
Boggs, Steven E.0000-0001-9567-4224
Harrison, Fiona A.0000-0003-2992-8024
Madsen, Kristin K.0000-0003-1252-4891
Stern, Daniel0000-0003-2686-9241
Alternate Title:NuSTAR discovery of a 3.76-second transient magnetar near Sagittarius A*
Additional Information:© 2013 American Astronomical Society. Received 2013 May 7; accepted 2013 May 14; published 2013 May 30. This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. The authors thank Arash Bodaghee and Clio Sleator for their assistance with data analysis and Brian Metzger for helpful discussions.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:Galaxy: center; pulsars: general; pulsars: individual (SGR J1745-29); stars: neutron
Record Number:CaltechAUTHORS:20130812-081440101
Persistent URL:
Official Citation: NuSTAR Discovery of a 3.76 s Transient Magnetar Near Sagittarius A* Kaya Mori, Eric V. Gotthelf, Shuo Zhang, Hongjun An, Frederick K. Baganoff, Nicolas M. Barrière, Andrei M. Beloborodov, Steven E. Boggs, Finn E. Christensen, William W. Craig, Francois Dufour, Brian W. Grefenstette, Charles J. Hailey, Fiona A. Harrison, Jaesub Hong, Victoria M. Kaspi, Jamie A. Kennea, Kristin K. Madsen, Craig B. Markwardt, Melania Nynka, Daniel Stern, John A. Tomsick, and William W. Zhang doi:10.1088/2041-8205/770/2/L23
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39856
Deposited By: Ruth Sustaita
Deposited On:12 Aug 2013 16:09
Last Modified:11 Oct 2017 14:58

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