Hyper-massive Black Holes have Faint Broad and Narrow Emission Lines
| Autor: | Gary J. Ferland, Harshitha K Bhat, Susmita Chakravorty, Caroline Bertemes, Dhrubojyoti Sengupta, Sudeb Ranjan Datta, Nirupam Roy, Savithri H. Ezhikode, Martin Elvis |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
Accretion (meteorology) Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astronomy and Astrophysics Quasar Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics - Astrophysics of Galaxies Spectral line Space and Planetary Science Ionization Astrophysics of Galaxies (astro-ph.GA) Emission spectrum Equivalent width Schwarzschild radius Astrophysics::Galaxy Astrophysics Line (formation) |
| DOI: | 10.48550/arxiv.2007.01438 |
| Popis: | The EUV provides most of the ionization that creates the high equivalent width (EW) broad and narrow emission lines (BELs, NELs) of quasars. Spectra of Hypermassive Schwarzschild black holes (HMBHs, $M_{BH} \geq 10^{10} M_{\odot}$) with $\alpha$-discs, decline rapidly in the EUV suggesting much lower EWs. Model spectra for black holes of mass $10^{6}-10^{12} M_{\odot}$ and accretion rates $0.03 \leq L_{bol}/L_{edd} \leq 1.0$ were input to the CLOUDY photoionization code. BELs become $\sim$100 times weaker in EW from $M_{BH} \sim 10^8 M_{\odot}$ to $M_{BH} \sim 10^{10} M_{\odot}$. The high ionization BELs (O VI 1034 $\overset{\circ}{\mathrm {A}}$, C IV 1549 $\overset{\circ}{\mathrm {A}}$, He II 1640 $\overset{\circ}{\mathrm {A}}$) decline in EW from ($M_{BH} \geq 10^6 M_{\odot}$, reproducing the Baldwin effect, but regain EW for $M_{BH} \geq 10^{10} M_{\odot}$). The low ionization lines (MgII 2798 $\overset{\circ}{\mathrm {A}}$, H$\beta$ 4861 $\overset{\circ}{\mathrm {A}}$ and H$\alpha$ 6563 $\overset{\circ}{\mathrm {A}}$) remain weak. Lines for maximally spinning HMBHs behave similarly. Line ratio diagrams for the BELs show that high OVI/H$\beta$ and low CIV/H$\alpha$ may pick out HMBH, although OVI is often hard to observe. In NEL BPT diagrams HMBHs lie among star-forming regions, except for highly spinning, high accretion rate HMBHs. In summary, the BELs expected from HMBHs would be hard to detect using the current optical facilities. From 100 to $10^{12} M_{\odot}$, the emission lines used to detect AGN only have high EW in the $10^6 - 10^9 M_{\odot}$ window, where most AGN are found. This selection effect may be distorting reported distributions of $M_{BH}$. Comment: 20 pages, 26 figures, to be published in MNRAS |
| Databáze: | OpenAIRE |
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