In the News (and continuing on our Black Hole theme we seem to have running at the moment): scientists are speculating about the symbiotic relationship between Super Massive Black hole growth and Galaxy formation.
Astronomy without a telescope - black hole evolution
Quote:
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While only observable by inference, the existence of supermassive black holes (SMBHs) at the centre of most – if not all – galaxies remains a compelling theory supported by a range of indirect observational methods. Within these data sources, there exists a strong correlation between the mass of the galactic bulge of a galaxy and the mass of its central SMBH – meaning that smaller galaxies have smaller SMBHs and bigger galaxies have bigger SMBHs.
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For the record, a nice summary of the present status of the observational supporting 'evidence' for SMBHs is:
i) the
mass of a galactic bulge is generally inferred from the velocity dispersion of its stars;
ii) the
presence of supermassive black holes in the centre of such bulges i
s inferred from the very fast radial motion of inner stars (at least in closer galaxies where we can observe individual stars);
For galaxies too far away to observe individual stars:
iii)
the velocity dispersion and the presence of a central supermassive black hole
are both inferred, drawing on the what we have learnt from closer galaxies;
iv)
direct observations of broad emission lines are interpreted as the product of very rapid orbital movement of gas around an SMBH (where the ‘broadening’ of these lines is a result of the Doppler effect).
Overall,
despite the assumptions built on assumptions nature of this work, ongoing observations continue to support and hence strengthen the theoretical model.
Cheers
