EVIDENCE FOR RAPIDLY ROTATING BLACK HOLES IN FANAROFF-RILEY I RADIO GALAXIES

Journal Article · Fri Jul 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/735/1/50· OSTI ID:21576536

Qingwen, Wu; Dingxiong, Wang ^[1]

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1. Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

We investigate the correlation between 151 MHz radio luminosity, L{sub 151MHz}, and jet power, P{sub jet}, for a sample of low-power radio galaxies, of which the jet power is estimated from X-ray cavities. The jet power for a sample of Fanaroff-Riley I radio galaxies (FR Is) is estimated with the derived empirical correlation. We find that P{sub jet}/L{sub Edd} is positively correlated with L{sub X}{sup 2-10keV}/L{sub Edd} for FR Is, where L{sub Edd} is the Eddington luminosity and L{sup 2-10keV}{sub X} is the 2-10 keV X-ray luminosity. We calculate the jet power of a hybrid model, as a variant of a Blandford-Znajek model proposed by Meier, based on the global solution of the advection-dominated accretion flow (ADAF) surrounding a Kerr black hole (BH). Our model calculations suggest that the maximal jet power is a function of the mass accretion rate and the BH spin parameter j. The hard X-ray emission is believed to be mainly from the ADAFs in FR Is, and the mass accretion rate is therefore constrained with the X-ray emission in our ADAF model calculations. We find that the dimensionless angular momentum of BH j {approx}> 0.9 is required in order to reproduce the observed relation of P{sub jet}/L{sub Edd}-L{sub X}{sup 2-10keV}/L{sub Edd} for FR Is. Our conclusion will be strengthened if part of the X-ray emission is contributed by the jets. Our results suggest that BHs in FR Is are rapidly spinning, which are almost not affected by the uncertainty of the BH mass estimates.

• OSTI ID: 21576536
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 735; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
CORRELATIONS
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
EMISSION
FLUID MECHANICS
GALAXIES
HARD X RADIATION
HYDRODYNAMICS
IONIZING RADIATIONS
JETS
LUMINOSITY
MAGNETOHYDRODYNAMICS
MASS
MATHEMATICAL SOLUTIONS
MECHANICS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
RADIO GALAXIES
X RADIATION
X-RAY GALAXIES