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Bright X-ray and Radio Pulses from a Recently Reactivated Magnetar

Pearlman, Aaron B. and Majid, Walid A. and Prince, Thomas A. and Ray, Paul S. and Kocz, Jonathon and Horiuchi, Shinji and Naudet, Charles J. and Enoto, Teruaki and Güver, Tolga and Arzoumanian, Zaven and Gendreau, Keith C. and Ho, Wynn C. G. (2020) Bright X-ray and Radio Pulses from a Recently Reactivated Magnetar. . (Unpublished)

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Magnetars are young, rotating neutron stars that possess larger magnetic fields (B ≈ 10¹³-10¹⁵G) and longer rotational periods (P ≈ 1-12 s) than ordinary pulsars. In contrast to rotation-powered pulsars, magnetar emission is thought to be fueled by the evolution and decay of their powerful magnetic fields. They display highly variable radio and X-ray emission, but the processes responsible for this behavior remain a mystery. We report the discovery of bright, persistent individual X-ray pulses from XTE J1810-197, a transient radio magnetar, using the Neutron star Interior Composition Explorer (NICER) following its recent radio reactivation. Similar behavior has only been previously observed from a magnetar during short time periods following a giant flare. However, the X-ray pulses presented here were detected outside of a flaring state. They are less energetic and display temporal structure that differs from the impulsive X-ray events previously observed from the magnetar class, such as giant flares and short X-ray bursts. Our high frequency radio observations of the magnetar, carried out simultaneously with the X-ray observations, demonstrate that the relative alignment between the X-ray and radio pulses varies on rotational timescales. No correlation was found between the amplitudes or temporal structure of the X-ray and radio pulses. The magnetar's 8.3 GHz radio pulses displayed frequency structure, which was not observed in the pulses detected simultaneously at 31.9 GHz. Many of the radio pulses were also not detected simultaneously at both frequencies, which indicates that the underlying emission mechanism producing these pulses is not broadband. We find that the radio pulses from XTE J1810-197 share similar characteristics to radio bursts detected from fast radio burst (FRB) sources, some of which are now thought to be produced by active magnetars.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Pearlman, Aaron B.0000-0002-8912-0732
Majid, Walid A.0000-0002-4694-4221
Prince, Thomas A.0000-0002-8850-3627
Ray, Paul S.0000-0002-5297-5278
Kocz, Jonathon0000-0003-0249-7586
Naudet, Charles J.0000-0001-6898-0533
Enoto, Teruaki0000-0003-1244-3100
Güver, Tolga0000-0002-3531-9842
Ho, Wynn C. G.0000-0002-6089-6836
Additional Information:The authors would like to thank Ben Stappers for providing a radio ephemeris of the Crab pulsar and Jim Palfreyman for supplying a radio ephemeris of the Vela pulsar. We are also grateful to Wenbin Lu for valuable discussions. A.B.P. acknowledges support by the Department of Defense (DoD) through the National Defense Science and Engineering Graduate (NDSEG) Fellowship Program and by the National Science Foundation (NSF) Graduate Research Fellowship under Grant No. DGE-1144469. T.E. is supported by JSPS/MEXT KAKENHI grant number 18H01246. We thank the Jet Propulsion Laboratory’s Research and Technology Development program and Caltech’s President’s and Director’s Fund for partial support at JPL and the Caltech campus. A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology and the Caltech campus under a Research and Technology Development Grant through a contract with the National Aeronautics and Space Administration (NASA). U.S. government sponsorship is acknowledged. We acknowledge support from the DSN team for scheduling and carrying out the radio observations. We also thank Charles Lawrence for providing programmatic support for this work. This work was supported by NASA through the NICER mission and the Astrophysics Explorers Program, and made use of data and software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC). Portions of this work performed at the United States Naval Research Laboratory (NRL) were supported by NASA. The authors declare that they have no competing financial interests. Author Contributions: A.B.P. was the primary author of the manuscript, led the X-ray and radio data analysis, and produced the figures. A.B.P. carried out the pulsar timing and pulsation analyses with contributions from W.A.M. A.B.P., P.S.R., W.A.M., and J.K. aligned the folded X-ray and radio light curves. W.A.M. and C.J.N. coordinated the radio and X-ray observations with S.H., Z.A., and K.C.G. A.B.P.,W.A.M., T.A.P., P.S.R., T.E., T.G., Z.A., and W.C.G.H. contributed to the physical interpretation of the results. A.B.P., W.A.M., T.A.P., P.S.R., J.K., S.H., T.E., T.G., Z.A., and W.C.G.H. edited the manuscript. W.A.M. is the PI of a DSN proposal focused on monitoring XTE J1810–197 during its recent outburst. W.A.M., T.E., and T.G. are co-PIs of the NICER Target of Opportunity (ToO) proposal. K.C.G. is the PI of NICER, Z.A. is the Deputy PI and Science Lead for NICER, and T.E. is the leader of the magnetar and magnetosphere science subgroup of NICER. T.A.P. is A.B.P.’s Ph.D. advisor. Data Availability: A catalog of the NICER and DSN observations is provided in Table 1. The X-ray observations are accessible through the High Energy Astrophysics Science Archive Research Center (HEASARC) data archive8h. The radio data used in this paper are available from the corresponding author upon reasonable request. Code Availability: The corresponding author will provide the codes used to analyze the observations described in this paper upon reasonable request.
Funding AgencyGrant Number
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
Japan Society for the Promotion of Science (JSPS)18H01246
JPL Research and Technology Development FundUNSPECIFIED
Caltech President’s FundUNSPECIFIED
Record Number:CaltechAUTHORS:20200720-072558056
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104436
Deposited By: Tony Diaz
Deposited On:20 Jul 2020 16:20
Last Modified:20 Jul 2020 16:20

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