High-density disc reflection spectroscopy of low-mass active galactic nuclei
Mallick L, Fabian AC, Garcia JA, Tomsick JA, Parker ML, Dauser T, Wilkins DR, De Marco B, Steiner JF, Connors RMT, Mastroserio G, Markowitz AG, Pinto C, Alston WN, Lohfink AM, Gandhi P (2022)
Publication Type: Journal article
Publication year: 2022
Journal
Book Volume: 513
Pages Range: 4361-4379
Journal Issue: 3
Abstract
The standard alpha-disc model predicts an anticorrelation between the density of the inner accretion disc and the black hole mass times square of the accretion rate, as seen in higher mass (M-BH > 10(6) M-circle dot) active galactic nuclei (AGNs). In this work, we test the predictions of the alpha-disc model and study the properties of the inner accretion flow for the low-mass end (M-BH approximate to 10(5-6) M-circle dot) of AGNs. We utilize a new high-density disc reflection model where the density parameter varies from n(e) = 10(15) to 10(20) cm(-3) and apply it to the broad-band X-ray (0.3-10 keV) spectra of the low-mass AGN sample. The sources span a wide range of Eddington fractions and are consistent with being sub-Eddington or near-Eddington. The X-ray spectra reveal a soft X-ray excess below similar to 1.5 keV which is well modelled by high-density reflection from an ionized accretion disc of density n(e) similar to 10(18) cm(-3) on average. The results suggest a radiation pressure-dominated disc with an average of 70 per cent fraction of the disc power transferred to the corona, consistent with that observed in higher mass AGNs. We show that the disc density higher than 10(15) cm(-3) can result from the radiation pressure compression when the disc surface does not hold a strong magnetic pressure gradient. We find tentative evidence for a drop in black hole spin at low-mass regimes.
Authors with CRIS profile
Involved external institutions
Stanford University
United States (USA) (US)
Polska Akademia Nauk (PAN) / Polish Academy of Sciences
Poland (PL)
Harvard-Smithsonian Center for Astrophysics (CfA)
United States (USA) (US)
California Institute of Technology (Caltech)
United States (USA) (US)
Institute of Space Astrophysics and Cosmic Physics / Palermo Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF)
Italy (IT)
European Space Astronomy Centre (ESAC)
Spain (ES)
Montana State University
United States (USA) (US)
University of Cambridge
United Kingdom (GB)
University of California, Berkeley
United States (USA) (US)
University of Southampton
United Kingdom (GB)
United States (USA) (US)
Polska Akademia Nauk (PAN) / Polish Academy of Sciences
Poland (PL)
Harvard-Smithsonian Center for Astrophysics (CfA)
United States (USA) (US)
California Institute of Technology (Caltech)
United States (USA) (US)
Institute of Space Astrophysics and Cosmic Physics / Palermo Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF)
Italy (IT)
European Space Astronomy Centre (ESAC)
Spain (ES)
Montana State University
United States (USA) (US)
University of Cambridge
United Kingdom (GB)
University of California, Berkeley
United States (USA) (US)
University of Southampton
United Kingdom (GB)
How to cite
APA:
Mallick, L., Fabian, A.C., Garcia, J.A., Tomsick, J.A., Parker, M.L., Dauser, T.,... Gandhi, P. (2022). High-density disc reflection spectroscopy of low-mass active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 513(3), 4361-4379. https://dx.doi.org/10.1093/mnras/stac990
MLA:
Mallick, Labani, et al. "High-density disc reflection spectroscopy of low-mass active galactic nuclei." Monthly Notices of the Royal Astronomical Society 513.3 (2022): 4361-4379.
BibTeX: Download