VLA Observations of Single Pulses from the Galactic Center Magnetar

Abstract

We present the results of a 7-12 GHz phased-array study of the Galactic center magnetar J1745−2900 with the Karl G. Jansky Very Large Array (VLA). Using data from two 6.5 hour observations from September 2014, we find that the average profile is comprised of several distinct components at these epochs and is stable over ∼day timescales and ∼GHz frequencies. Comparison with additional phased VLA data at 8.7 GHz shows significant profile changes on longer timescales. The average profile at 7-12 GHz is dominated by the jitter of relatively narrow pulses. The pulses in each of the four main profile components seen in September 2014 are uncorrelated in phase and amplitude, though there is a small but significant correlation in the occurrence of pulses in two of the profile components. Using the brightest pulses, we measure the dispersion and scattering parameters of J1745−2900. A joint fit of 38 pulses gives a 10 GHz pulse broadening time of τ sc,10 = 0.09 ± 0.03 ms and a dispersion measure of DM = 1760 +2.4 −1.3 pc cm −3 . Both of these results are consistent with previous measurements, which suggests that the scattering and dispersion measure of J1745−2900 may be stable on timescales of several years.

The FRB 20121102A November rain in 2018 observed with the Arecibo Telescope

“…These two bursts were only 1.4 s apart and within the same rotation. Other magnetars (Pearlman et al 2018;Wharton et al 2019) and pulsar giant pulses (see e.g. Karuppusamy et al 2010;Geyer et al 2021) can as well occur multiple times within a rotational period, which produces bimodality in the waittimes, similar to the one we see in FRB 121102.…”

“…Apart from these similarities magnetars emit in radio only in parts of their rotational phase (Pearlman et al 2018), while no such rotational period has been found in FRB 121102 (Zhang 2018;Cruces et al 2021;Aggarwal et al 2021;Li et al 2021b;Hewitt et al 2021, and Section 4.5). The Galactic centre magnetar J1745−2900 can, however, emit radio pulses in ∼70 % of its rotational phase, although they are clustered in smaller windows (Wharton et al 2019). In the context of a rotating magnetar with stable emission regions we can constrain the rotational period to be between the two observed peaks, but several scenarios could make the period unobservable.…”

An 86 GHz Search for Pulsars in the Galactic Center with the Atacama Large Millimeter / submillimeter Array

“…The single pulses occur at phases corresponding to the trailing part of the integrated profile. The subpulse structure is seen in all three cases, as also reported from previous single-pulse studies of the GC magnetar at lower frequencies (Pearlman et al 2018;Wharton et al 2019).…”

Sub-second periodicity in a fast radio burst

“…26 On the other hand, if the periodicities reported for FRBs 20210206A and 20210213A are real, the larger jitters observed are more similar to the values measured for Galactic radio magnetars. [27][28][29][30] For example, FRBs 20210206A and 20210213A both have observed periodicities (see Extended Data Table 2) that are comparable to the characteristic delay time between successive radio pulse components measured from the Galactic Centre magnetar, PSR J1745-2900, over many rotational cycles. 29 In the case of the Galactic Center magnetar, it is not evident that this characteristic timescale is related to the magnetar's rotational period.…”