The BBC's Milky Way's centre exploded 3.5 million years ago says:
A cataclysmic energy flare ripped through our galaxy, the Milky Way, about 3.5 million years ago, a team of astronomers say.
They say the so-called Sifter flare started near the super massive black hole in the centre of the galaxy.
The impact was felt 200,000 light-years away.
[...]The flare created two enormous "ionisation cones" that sliced through the Milky Way.
It mentions "The team - led by Professor Joss Bland-Hawthorn from Australia" and "co-author Magma Guglielmo from the University of Sydney" and says "The findings will be published in the Astrophysical Journal."
Right now I'm just asking the following:
Question: Who is Sifter, and what is "the so-called Sifter flare"?
update: @bertieb's comment notes that the BBC has corrected the passage. The new sentence says:
The so-called Seyfert flare started near the supermassive black hole in the centre of the galaxy, they add.
When first published, the article called it a "so-called Sifter flare" and that's what originally inspired this question.