[Astro] [CAPT] Astro seminar Wed 14th May 15:45 C4 -- Clive Tadhunter (Sheffield)
Luke Conaboy
Luke.Conaboy at nottingham.ac.uk
Mon May 12 09:11:41 BST 2025
Hi all,
this week our seminar is given by Clive Tadhunter (Sheffield), details below. The seminar will be in C4.
Post-seminar refreshments will be wine and cheese.
Timings are as usual:
- lunch at Lakeside, leaving CAPT ~13:00 (subsidised for a limited number of students -- let me know before the end of the day tomorrow)
- meet the speaker for postgrads at 15:00, finishing at 15:30
- seminar at 15:45 in C5/C4
- post-seminar wine and cheese at 16:45
This seminar will be conducted in person only.
Best,
Jesse and Luke
==
Triggering quasars in the local universe
The literature contains conflicting claims on the importance of mergers in triggering the most luminous quasar-like AGN activity. Part of this may be related to the classification methodology and issues surrounding the subtraction of the bright nuclear psf for the type I AGN, but I will argue that the dominant factor is likely to be surface brightness depth. This can explain the apparent differences between HST- and ground-based estimates of merger rates for quasar host galaxies. Using new results from ground-based observations with high surface brightness depth of samples of 3CR, 2Jy and SDSS-selected type 2 quasar sources as an example, I will demonstrate that mergers are likely to be the dominant, if not sole, triggering mechanism for quasars in the local Universe. I will also stress that cosmological surface brightness dimming makes it particularly challenging to establish merger rates for quasar host galaxies at high redshifts. Finally, I will show how multi-wavelength observations can be used to investigate the nature of the triggering mergers.
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