TY - JOUR
T1 - The High-frequency Radio Emission of the Galactic Center Magnetar SGR J1745-29 during a Transitional Period
AU - Gelfand, Joseph D.
AU - Ransom, Scott
AU - Kouveliotou, Chryssa
AU - Granot, Jonathan
AU - Van Der Horst, Alexander J.
AU - Zhang, Guobao
AU - Göǧüş, Ersin
AU - Roberts, Mallory S.E.
AU - Ali, Hend Al
N1 - Funding Information:
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. J.D.G. acknowledges the support of the NYU Abu Dhabi Research Enhancement Fund under grant RE022.
Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/11/20
Y1 - 2017/11/20
N2 - The origin of the high-frequency radio emission detected from several magnetars is poorly understood. In this paper, we report the ~40 GHz properties of SGR J1745-29 measured using Jansky Very Large Array (JVLA) and Robert C. Byrd Green Bank Telescope (GBT) observations between 2013 October 26 and 2014 May 31. Our analysis of a Q-band (45GHz)GBT observation on 2014 April 10 resulted in the earliest detection of pulsed radio emission at high frequencies (>20GHz); we found that the average pulse has a singly peaked profile with width ~75ms (~2% of the 3.764 s pulse period) and an average pulsed flux density of ~100 mJy. We also detected very bright, short (<10 ms) single pulses during ~70% of this neutron star's rotations, and the peak flux densities of these bright pulses follow the same log-normal distribution as measured at 8.5 GHz. Additionally, our analysis of contemporaneous JVLA observations suggest that its 41/44 GHz flux density varied between ~1-4mJy during this period, with a ~ 2 change observed on ~20 minute timescales during a JVLA observation on 2014 May 10. Such a drastic change over short timescales is inconsistent with the radio emission resulting from a shock powered by the magnetar's supersonic motion through the surrounding medium, but consistent with pulsed emission generated in its magnetosphere.
AB - The origin of the high-frequency radio emission detected from several magnetars is poorly understood. In this paper, we report the ~40 GHz properties of SGR J1745-29 measured using Jansky Very Large Array (JVLA) and Robert C. Byrd Green Bank Telescope (GBT) observations between 2013 October 26 and 2014 May 31. Our analysis of a Q-band (45GHz)GBT observation on 2014 April 10 resulted in the earliest detection of pulsed radio emission at high frequencies (>20GHz); we found that the average pulse has a singly peaked profile with width ~75ms (~2% of the 3.764 s pulse period) and an average pulsed flux density of ~100 mJy. We also detected very bright, short (<10 ms) single pulses during ~70% of this neutron star's rotations, and the peak flux densities of these bright pulses follow the same log-normal distribution as measured at 8.5 GHz. Additionally, our analysis of contemporaneous JVLA observations suggest that its 41/44 GHz flux density varied between ~1-4mJy during this period, with a ~ 2 change observed on ~20 minute timescales during a JVLA observation on 2014 May 10. Such a drastic change over short timescales is inconsistent with the radio emission resulting from a shock powered by the magnetar's supersonic motion through the surrounding medium, but consistent with pulsed emission generated in its magnetosphere.
KW - general - stars
KW - individual (J1745-29) - radio continuum
KW - magnetars
KW - pulsars
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U2 - 10.3847/1538-4357/aa9436
DO - 10.3847/1538-4357/aa9436
M3 - Article
AN - SCOPUS:85037698339
SN - 0004-637X
VL - 850
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 53
ER -