Radio News: Second persistently active fast radio burst discovered
Andrew Jones reports for Space.com that astronomers have discovered a second persistently active fast radio burst. There have been about 500 fast radio bursts -- intense, brief flashes of radio-frequency emissions, lasting for milliseconds -- found since the phenomenon was discovered in 2007. But only two are associated with a persistent radio source, and this one is within the fringes of a dwarf galaxy nearly three billion light-years from Earth. What causes these highly energetic transmissions is a mystery. Astronomers guess that the average FRB releases as much energy in a millisecond as the Sun puts out in three days. Most use radio frequencies around 1400 MHz; while a few have been detected at lower frequencies in the range of 400–800 MHz. "The big surprise for me was realizing that the new FRB seems to be such a perfect 'twin' to an earlier discovery," Casey Law, an astronomer at Caltech. "Perhaps some would have preferred to say that the first such association [between an FRB and radio source] was a coincidence, because it was hard to explain. Now the second example shows that this is a real and critical part of the life of an FRB." Di Li, of the National Astronomical Observatories of China (NAOC) and lead of the Commensal Radio Astronomy FAST Survey which detected the latest fast radio burst, told Space.com via email. "I personally favor an evolutionary picture in that all sources repeat, but the activity level drops precipitously as the source ages. Since FRB 20190520B is only the second of around 500 known FRBs to have a so-called PRS counterpart and both are extremely active, they could, in this hypothetical evolutionary picture, represent FRBs' youth, which lasts not very long." Read more about this story at Space.com.