Radio signal coming from another galaxy detected by scientists

Poor quality article implying that these are alien signals

What natural physical mechanism is likely to create FRBs?

An antenna might be plasma gasses. This must be fed with an alternating current; perhaps a brief physical phenomena like a landslide of ionized material on the surface of a dense object. If the two are in close proximity and happen to be resonant it will radiate RF power.

Doesn't appear that hard to conceive of given scale and diversity of the universe.

I suspect the term "population" when referring to the signal is misleading (as in, it is most likely _not_ a "population of aliens sentient being emitting radio signal to report rush hour traffic" ; but the author enjoyed the ambiguity to earn some views). What would be the meaning, in context ?

Are there any known cosmological phenomena that would produce fast radio bursts? Even if not on a periodic basis; just at all?

Obviously it is a big leap to assume this is evidence of ETs, but do we have any plausible explanations – besides that one – for what could be causing this?