| Abstract |
The most reliable single-epoch supermassive black hole mass ($M_{\rm BH}$) estimates in quasars are obtained by using the velocity widths of low-ionization emission lines, typically the H$\beta$ $\lambda4861$ line. Unfortunately, this line is redshifted out of the optical band at $z\approx1$, leaving $M_{\rm BH}$ estimates to rely on proxy rest-frame ultraviolet (UV) emission lines, such as C IV $\lambda1549$ or Mg II $\lambda2800$, which contain intrinsic challenges when measuring, resulting in uncertain $M_{\rm BH}$ estimates. In this work, we aim at correcting $M_{\rm BH}$ estimates derived from the C IV and Mg II emission lines based on estimates derived from the H$\beta$ emission line. We find that employing the equivalent width of C IV in deriving $M_{\rm BH}$ estimates based on Mg II and C IV provides values that are closest to those obtained from H$\beta$. We also provide prescriptions to estimate $M_{\rm BH}$ values when only C IV, only Mg II, and both C IV and Mg II are measurable. We find that utilizing both emission lines, where available, reduces the scatter of UV-based $M_{\rm BH}$ estimates by $\sim15\%$ when compared to previous studies. Lastly, we discuss the potential of our prescriptions to provide more accurate and precise estimates of $M_{\rm BH}$ given a much larger sample of quasars at $3.20 \lesssim z \lesssim 3.50$, where both Mg II and H$\beta$ can be measured in the same near-infrared spectrum. |
| Authors |
Cooper Dix  , Brandon M. Matthews , Ohad Shemmer , Michael S. Brotherton  , Adam D. Myers , I. Andruchow , W. N. Brandt , Gabriel A. Ferrero , Richard F. Green , P. Lira , Richard M. Plotkin , Gordon T. Richards , Donald P. Schneider
|
| Journal Info |
IOP Publishing | The Astrophysical Journal , vol: 950
, iss: 2
, pages: 96 - 96
|
| Publication Date |
6/1/2023 |
| ISSN |
0004-637X |
Type |
article |
| Open Access |
gold
|
| DOI |
https://doi.org/10.3847/1538-4357/acd04b |
| Keywords |
Gravitational Lensing (Score: 0.468601)
|
