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The BH mass – galaxy scaling relations in the local Universe: what is the role of type 2 AGN?
7 novembre 2017 @ 11:45 - 12:45
Coevolutionary models that link the growth of supermassive black holes (BHs) and of their host galaxies are based on the observations of tight scaling relations between the BH mass and some properties of the host bulge. These relations have been calibrated thanks to the direct measurements of the BH mass in local galaxies and are extremely important, used to measure BH masses at high redshift and to determine the distribution of accreted mass, i.e. the black hole mass function.
However, these relations seem to be biased in favour of the more massive BHs, due to a bias in the resolution of the BH sphere of influence. Hence, there is urgent need to explore the full distribution of BH masses, accumulating sources below 1e+7 solar masses.
I here present the results from a systematic study performed using deep NIR (VLT and LBT) spectroscopy of a sample of ~40 type 2 active galactic nuclei (AGN), drawn from the complete SWIFT/BAT 70-month hard (14-195 keV) X-ray catalogue. Thanks to our new virial relation based on unbiased physical quantities, i.e. hard X-ray luminosity and Paβ emission line FWHM, we have been able to measure for the first time in a virial way the supermassive black hole masses of type 2 AGN, whose values have been up today estimated using indirect proxies (e.g. from scaling relations). With direct virial masses for type 2 AGN, we discuss, for the first time, if the BH-host galaxy scaling relations hold for type 2 AGN, thus putting a missing piece to the AGN/galaxy co-evolution puzzle.