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PROBING THE BALANCE OF AGN AND STAR-FORMING ACTIVITY IN THE LOCAL UNIVERSE WITH ChaMP
- Source :
- The Astrophysical Journal. 705:1336-1355
- Publication Year :
- 2009
- Publisher :
- American Astronomical Society, 2009.
-
Abstract
- The combination of the SDSS and the Chandra Multiwavelength Project (ChaMP) currently offers the largest and most homogeneously selected sample of nearby galaxies for investigating the relation between X-ray nuclear emission, nebular line-emission, black hole masses, and properties of the associated stellar populations. We present here novel constraints that both X-ray luminosity Lx and X-ray spectral energy distribution bring to the galaxy evolutionary sequence H II -> Seyfert/Transition Object -> LINER -> Passive suggested by optical data. In particular, we show that both Lx and Gamma, the slope of the power-law that best fits the 0.5 - 8 keV spectra, are consistent with a clear decline in the accretion power along the sequence, corresponding to a softening of their spectra. This implies that, at z ~ 0, or at low luminosity AGN levels, there is an anti-correlation between Gamma and L/Ledd, opposite to the trend exhibited by high z AGN (quasars). The turning point in the Gamma -L/Ledd LLAGN + quasars relation occurs near Gamma ~ 1.5 and L/Ledd ~ 0.01. Interestingly, this is identical to what stellar mass X-ray binaries exhibit, indicating that we have probably found the first empirical evidence for an intrinsic switch in the accretion mode, from advection-dominated flows to standard (disk/corona) accretion modes in supermassive black hole accretors, similar to what has been seen and proposed to happen in stellar mass black hole systems. The anti-correlation we find between Gamma and L/Ledd may instead indicate that stronger accretion correlates with greater absorption. Therefore the trend for softer spectra toward more luminous, high redshift, and strongly accreting AGN/quasars could simply be the result of strong selection biases reflected in the dearth of type 2 quasar detections.<br />23 pages, 8 figures, 1 long (3 page) table, to appear in ApJ
- Subjects :
- High Energy Astrophysical Phenomena (astro-ph.HE)
Physics
Supermassive black hole
Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Stellar mass
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astronomy and Astrophysics
Quasar
Astrophysics::Cosmology and Extragalactic Astrophysics
Astrophysics
Accretion (astrophysics)
Galaxy
Redshift
Luminosity
Black hole
Space and Planetary Science
Astrophysics::Solar and Stellar Astrophysics
Astrophysics - High Energy Astrophysical Phenomena
Astrophysics::Galaxy Astrophysics
Astrophysics - Cosmology and Nongalactic Astrophysics
Subjects
Details
- ISSN :
- 15384357 and 0004637X
- Volume :
- 705
- Database :
- OpenAIRE
- Journal :
- The Astrophysical Journal
- Accession number :
- edsair.doi.dedup.....dad2b0f5268f5fb057e708677bbf79c9