What can we learn about quasars from αOX measurements in Galactic black hole binaries?

TY - JOUR

T1 - What can we learn about quasars from αOX measurements in Galactic black hole binaries?

AU - Sobolewska, Małgorzata A.

AU - Gierliński, Marek

AU - Siemiginowska, Aneta

PY - 2009/4/11

Y1 - 2009/4/11

N2 - We draw a comparison between active galactic nuclei (AGN) and Galactic black hole binaries (GBHs) using a uniform description of spectral energy distribution of these two classes of X-ray sources. We parametrize spectra of GBHs with an α GBH parameter which we define as a slope of a nominal power-law function between 3 and 20 keV. We show that this parameter can be treated as an equivalent of the X-ray loudness, α OX, used to describe AGN spectra. We do not find linear correlation between the α GBH and disc flux (similar to that between α OX and optical/UV luminosity found in AGN). Instead, we show that α GBH follows a well-defined pattern during a GBH outburst. We find that α GBH tend to cluster around 1, 1.5 and 2, which corresponds to the hard, very high/intermediate and soft spectral states, respectively. We conclude that majority of the observed Type 1 radio quiet AGN are in the spectral state corresponding to the very high/intermediate state of GBHs. The same conclusion is valid for radio-loud AGN. We also study variations of the spectral slopes (α GBH and the X-ray photon index, Γ) as a function of disc and Comptonization fluxes. We discuss these dependencies in the light of correlations of α OX and Γ with the optical/UV and X-ray 2 keV fluxes considered for AGN and quasars.

AB - We draw a comparison between active galactic nuclei (AGN) and Galactic black hole binaries (GBHs) using a uniform description of spectral energy distribution of these two classes of X-ray sources. We parametrize spectra of GBHs with an α GBH parameter which we define as a slope of a nominal power-law function between 3 and 20 keV. We show that this parameter can be treated as an equivalent of the X-ray loudness, α OX, used to describe AGN spectra. We do not find linear correlation between the α GBH and disc flux (similar to that between α OX and optical/UV luminosity found in AGN). Instead, we show that α GBH follows a well-defined pattern during a GBH outburst. We find that α GBH tend to cluster around 1, 1.5 and 2, which corresponds to the hard, very high/intermediate and soft spectral states, respectively. We conclude that majority of the observed Type 1 radio quiet AGN are in the spectral state corresponding to the very high/intermediate state of GBHs. The same conclusion is valid for radio-loud AGN. We also study variations of the spectral slopes (α GBH and the X-ray photon index, Γ) as a function of disc and Comptonization fluxes. We discuss these dependencies in the light of correlations of α OX and Γ with the optical/UV and X-ray 2 keV fluxes considered for AGN and quasars.

KW - Accretion, accretion discs

KW - Galaxies: active

KW - Quasars: general

KW - X-ray: binaries

KW - X-rays: galaxies

UR - https://www.scopus.com/pages/publications/63549106655

U2 - 10.1111/j.1365-2966.2009.14436.x

DO - 10.1111/j.1365-2966.2009.14436.x

M3 - Article

AN - SCOPUS:63549106655

SN - 0035-8711

VL - 394

SP - 1640

EP - 1648

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -