Group 1 Measurement of Black Hole mass

Supermassiveblackhole_nasajpl2_l2Nowadays, it is popular to measure black hole mass by reverberation mapping (RM) technique. However, its accuracy is only 0.3-0.4dex from the RM, and 0.5dex from the empirical $R-L$ relationship. The accuracy mainly depends on several factors: the viral factor, profile of $H_{\beta}$, the precision of RM observation and the intrinsic scatters of $R-L$ relationship. Furthermore, it is poorly examined by observations to extend the scope of the empirical relation to high redshift through UV emission lines for black hole mass though it has been widely used in literatures. On the other hand, after the efforts of 30 years, the RM measurements have been done only for 60-70 objects, in particular, both ends of low and high luminous AGNs have been poorly understood (only three high luminous quasars). The current mapped sample is not homogeneous and biased somehow.

This group will devote to develop the various techniques of measuring black hole mass with high precision including advanced data analysis, such as improved methods to remove the contamination of host galaxies and the effects of slit mis-centering. As newly developed technique, Markov Chain Monte Carlo (MCMC) simulations offer high accurate measurements of black hole mass has been applied to RM data fro black hole mass. We will improve the techniques more feasible for broader scope of masses, luminosities, accretion rates and redshifts.

According to accretion rates, AGNs in two extreme ends have not been systematically studied: those with very low accretion rates (ADAF disk) and with very high accretion rates (slim accretion disk). Jian-Min Wang’s team has been monitoring super-Eddington accreting massive black holes (SEAMBHs) in AGNs for the first time since 2012, and made a progress in understanding the BLR and accretion physics. It has been shown that 1) the $H_{\beta}$ lags are much shorter than the objects with same luminosity and depend on accretion rates; and 2) saturated luminosity appears, which was predicted by the model of slim accretion disks (Abramowicz et al. 1988). Clearly, it urgently needs to be tested in a larger sample, and to compare with a more uniform sample with wide range of the accretion rates. The future sample of this PROJECT will be selected from Veron catalogue, PG quasars, LAMOST and SDSS database for all major kinds of AGNs, such as broad absorption lines, radio-loud and radio-quiet quasars and so on.


On the other hand, there is growing evidence for more complicated response of the broad emission lines with the varying continuum than the canonic $R-L$ relation. High quality campaigns are urgently needed to reveal the mysterious BLR. Therefore, we will focus on a carefully selected sample (referred to as “refined sample”) with high cadence and high sign-noise ratio spectra. This allows us to get the 3D structure of the BLR for black hole mass through MCMC technique.