On the origin of X-ray emission in some FR Is: ADAF or jet?
We investigate the X-ray origin in FR Is using the radio, submillimetre, optical, and Chandra X-ray data of a small sample consisting of eight FR I sources. These sources are very dim, with X-ray luminosities LX/LEdd～10-4-10-8(LX is the X-ray luminosity between 2-10 keV). We try to fit the multiwaveband spectrum using a coupled accretion-jet model. In this model, the accretion flow is described by an advection-dominated accretion flow (ADAF) while in the innermost region of ADAF a fraction of accretion flow is transferred into the vertical direction and forms a jet. We find that X-ray emission in the source with the highest LX (～1.8×10-4 LEdd) is from the ADAF. The results for the four sources with moderate LX (～several×10-6LEdd) are complicated. Two are mainly from the ADAFs, one from the jet, and the other from the sum of the jet and ADAF. The X-ray emission in the three least luminous sources (LX <～1.0×10-6 LEdd) is dominated by the jet although for one source it can also be interpreted by the ADAF since the quality of X-ray data is low. We conclude that these results roughly support the predictions of Yuan&Cui (2005) where they predict that when the X-ray luminosity of the system is below a critical value, the X-radiation will not be dominated by the emission from the ADAF any longer, but by the jet. We also investigate the fuel supply in these sources. We find that the accretion rates in four sources among the five in which we can have good constraints to their accretion rates must be higher than the Bondi rates. This implies that other fuel supply, such as the gas released by the stellar population inside the Bondi radius, should be important.
accretion accretion disks-galaxies: active-galaxies: nuclei-X-rays: galaxies
Qingwen Wu Feng Yuan Xinwu Cao
Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai,200030,China;Joint Institute Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai,200030,China;Joint Institute
国际会议
北京
英文
2007-04-21（万方平台首次上网日期，不代表论文的发表时间）