Periodic Windowed Behavior in SGR1935+2154 SGR Bursts. (arXiv:2006.16480v4 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Grossan_B/0/1/0/all/0/1">Bruce Grossan</a>
Two repeating FRB sources, FRB180916 (CHIME/FRB Collaboration, 2020) and
FRB121102 (Rajwade, et al., 2020) display periodic windowed behavior (PWB) in
the times of FRB detections. In PWB, events occur only within a periodic window
spanning some fraction of the period, but additionally, in FRB121102, no events
are detected at all during many of the periods. During 2020 May, coincident
soft gamma bursts and fast radio bursts (FRBs) observed from SGR1935+2154
(Zhang, et al., 2020) established a clear link between at least some FRBs and
soft gamma repeaters (SGR), and therefore magnetars. The analysis herein, which
selects the period giving the minimum window fraction, shows PWB in this
sources soft gamma-ray emission. For 174 bursts from 2014 through 2020 from IPN
(Interplanetary Network) instruments, a clearly resolved minimum in window
fraction vs. period occurrs at a 231 day period, and 55 percent window
fraction. Simulations show that PWB is not effectively identified by standard
chi-squared methods used for pulsars. The data cover only 6 bursting episodes;
discovery of events significantly outside the given windows could seriously
change these conclusions. However, it is shown that this result is robust:
First, the IPN has excellent time coverage and is unlikely to miss bursts
outside of these windows. For several data sub-samples, the same period was
found, and with large bursting episodes removed, the same period is among the
best two or three. Simulations show that even small numbers of random bursts
cannot show PWB; additionally, random events in the same number of periodic
windows as the data yield errors in the period of order 1 percent for even much
smaller data sets. These checks show the results are not due limited sampling.
The periodicity of this SGRs bursts should therefore provide critical hints as
to the mechanism behind the bursts, and by association, FRBs.
Two repeating FRB sources, FRB180916 (CHIME/FRB Collaboration, 2020) and
FRB121102 (Rajwade, et al., 2020) display periodic windowed behavior (PWB) in
the times of FRB detections. In PWB, events occur only within a periodic window
spanning some fraction of the period, but additionally, in FRB121102, no events
are detected at all during many of the periods. During 2020 May, coincident
soft gamma bursts and fast radio bursts (FRBs) observed from SGR1935+2154
(Zhang, et al., 2020) established a clear link between at least some FRBs and
soft gamma repeaters (SGR), and therefore magnetars. The analysis herein, which
selects the period giving the minimum window fraction, shows PWB in this
sources soft gamma-ray emission. For 174 bursts from 2014 through 2020 from IPN
(Interplanetary Network) instruments, a clearly resolved minimum in window
fraction vs. period occurrs at a 231 day period, and 55 percent window
fraction. Simulations show that PWB is not effectively identified by standard
chi-squared methods used for pulsars. The data cover only 6 bursting episodes;
discovery of events significantly outside the given windows could seriously
change these conclusions. However, it is shown that this result is robust:
First, the IPN has excellent time coverage and is unlikely to miss bursts
outside of these windows. For several data sub-samples, the same period was
found, and with large bursting episodes removed, the same period is among the
best two or three. Simulations show that even small numbers of random bursts
cannot show PWB; additionally, random events in the same number of periodic
windows as the data yield errors in the period of order 1 percent for even much
smaller data sets. These checks show the results are not due limited sampling.
The periodicity of this SGRs bursts should therefore provide critical hints as
to the mechanism behind the bursts, and by association, FRBs.
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