Multifrequency observations of SGR J1935+2154

ABSTRACT Magnetars are a promising candidate for the origin of fast radio bursts (FRBs). The detection an extremely luminous burst from Galactic magnetar SGR J1935+2154 on 2020 April 28 added credence to this hypothesis. We report simultaneous and non-simultaneous observing campaigns using Arecibo, Effelsberg, LOFAR, MeerKAT, MK2, Northern Cross telescopes MeerLICHT optical telescope in days months after event. did not detect any significant single pulses down fluence limits between 25 mJy ms 18 Jy ms. Some epochs overlapped with times when X-ray were detected. Radio images made 4 d MeerKAT revealed no point-like persistent or transient emission at location magnetar. No was detected over seven days. Using multicolour combined relations DM, NH, reddening, we constrain distance J1935+2154, be 1.5 6.5 kpc. upper limit is consistent some other indicators suggests that closer two orders magnitude less energetic than least FRBs. lack single-pulse detections shows range fluences either rare, highly clustered, both. It may also indicate lies somewhere being radio-quiet radio-loud terms its ability produce efficiently.