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Astronomy Tea Talk

Monday, April 4, 2022
4:00pm to 5:00pm
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Intermediate mass black holes everywhere?
James Paynter, University of Melbourne,

I present evidence for an intermediate mass black hole (IMBH) via a gravitationally lensed gamma-ray burst (GRB). In the first part of the talk I will speak about our detection methods, with the aim to convince you that our candidate is very much real. I will then speak about the lens itself, which being a few tens of thousands of solar masses and very compact is difficult to reconcile with anything but an IMBH. From here I estimate the cosmological density of such lenses, which rules out lensing by a globular cluster. Our estimated number density of 2000 per Megaparsec cubed is several orders of magnitudes above the current estimates for IMBH density. I then present more recent GRB lens candidates and update the estimated number density. I will also briefly speak about how lensing studies of radio candidates have found evidence for similar mass compact lenses. From here I collate work from many different authors to present how such a population could arise. I will also discuss our prospects for detecting these objects with eg. optical astronomy.

For more information, please contact Liam Connor by email at [email protected].