Are High-Redshift Spectroscopic Black Hole Mass Estimates Biased?
Abstract
Black hole (BH) masses estimated from single-epoch spectroscopyunderlie our understanding of the build-up of BHs from high redshiftto the present, but are currently based on a small sample of low-L,low-z reverberation mapped (RM) AGNs. The existing sample of RMAGNs appears to be biased against quasars where a radiation linedriven disk-wind dominates the broad emission line region (BELR). Assuch, we propose UV spectroscopy of 25 SDSS quasars at z 0.5 that haveluminosities comparable to the existing RM quasars, but that are morerepresentative of the BELR properties of the average quasar. Thesedata will enable us to confirm the bias in the RM quasar sample andlay the groundwork for reverberation mapping of quasars where windsaffect the BELR. This work is important because successful RMmeasurements of local AGNs have not been extended to the high-z,high-L regime, requiring extrapolation methods from low redshift. Thebest tool for this work comes from UV observations of the CIV emissionline region where it is possible to distinguish between virial- andwind-dominated BELRs. These measurements will further enable us tointer-compare BH masses computed using measurements from CIV, MgII,and Hbeta for each quasar. For this work we require spectral coverageof all the optical and UV broad emission lines (Ly-apha to H-beta) tocharacterize the diversity of quasar spectra, which we will thenrelate to BH mass, accretion rate and accretion disk physics. Thesedata will provide a powerful UV legacy database for investigations ofthe BELR structures of all quasars in addition to more robustbootstrapping of BH mass estimates from low to high redshift.
- Publication:
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HST Proposal
- Pub Date:
- October 2015
- Bibcode:
- 2015hst..prop14135R