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Spitzer Reveals Activities of Supermassive Black Holes in Elliptical Galaxies. Qiusheng Gu Nanjing University in collaboration with J.-S. Huang (CfA), G. Wilson (SSC), G. G. Fazio (CfA). SMBHs in Elliptical Galaxies. Ferrarese & Merritt, 2000, ApJ, 539, L9
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Spitzer Reveals Activities of Supermassive Black Holes in Elliptical Galaxies Qiusheng Gu Nanjing University in collaboration with J.-S. Huang (CfA), G. Wilson (SSC), G. G. Fazio (CfA)
SMBHs in Elliptical Galaxies Ferrarese & Merritt, 2000, ApJ, 539, L9 Gebhardt et al., 2000, ApJ, 539, L13.
SMBHs in Elliptical Galaxies • All galaxies contain supermassive black holes. • The mass of SMBH is tightly correlated with the mass of the bulge.
SMBHs in Elliptical Galaxies Bower et al. 1998, ApJ, 492, L111 D = 17 Mpc, 1” = 82 pc.
SMBHs in Elliptical Galaxies Bower et al. 1998, ApJ, 492, L111
SMBHs in Elliptical Galaxies • An S-shape velocity curve with a peak amplitude of 400 km s-1 at 0.1”(8 pc) from the nucleus. • A thin Keplerian disk fits the observed gas kinematics very well if the rotation axis of the gas disk is aligned with the radio jet axis. • A nuclear compact mass of 1.5×109M⊙with an uncertainty of (0.9-2.6)109M⊙
Es: QSOs’ hosts at high z • Radio-Loud QSOs • Exclusively in elliptical hosts • Radio-Quiet QSOs • MB<-24: 100% in bulge-dominant hosts • -21<MB<-24: 55% “ • MB<-21 (Sy1): 30% “ Floyd D. et al. 2004, MNRAS, 355, 196
SMBHs in local Ellipticals • In the Palomar sample, 57 Es 26 with pure absorption nuclei 4 Seyferts + 21 LINERs + 6 Transition
Spitzer: Powerful IR Telescope • IR bands less affected by extinction • Possible to detect the nuclear component as IR re-processed emission from a dusty torus(when stellar components properly removed)
Motivation • Wilson et al. (2006): at z ~1, 1/3 EROs are detected at 24 um; • Pozzi et al. (2006): at 0.9<z<2.08,8 EROs with high X-ray emission are all detected at 24um, 6 are elliptical galaxies. • EROs: Counterparts and progenitors of local massive E and S0 galaxies.
Motivation Wilson et al. 2006
Ks image with 24m contours (40" x40" ) Redshift: 0.9< z< 2.08 (Mignoli et al. 04)
6/8 EXTENDED de Vaucouleurs profile No AGN signature
Our Goal • To find the infrared indicator of SMBH activities in local elliptical galaxies; • To understand the origin of infrared emission in elliptical galaxies. • All Es in Ho’s sample with Spitzer IRAC observations. • We detected infrared-red cores in 6(24) Es
After removing stellar population … 4.5um-3.6um 5.8um-3.6um 8.0um-3.6um 24um
What is behind ? • IR emission mechanism: dust reradiation optical-UV-soft X-ray photons (AGNs/Starburst) --- dust --- infrared • The strength of SMBHs activities ? • The dust mass ?
Central Dust Structures Hubble WFPC2 image of NGC 315
Central Dust Structures Hubble WFPC2 image of NGC 4374
Hubble WFPC2 image of NGC 4278 Hubble WFPC2 image of NGC 5322 Adopt from Lauer et al., 2005, AJ, 129, 2138
Exception: Central Dust NGC 5077
NGC 4125 NGC 4552 Elliptical Galaxies without an Infrared-red Core NGC 7626 NGC 5813
Origin of Dust in Es • Internal origin : stellar mass loss • External origin: minor merger of small gas-rich satelliate system (Indications: off-set clouds , polar discs)
Origin of Dust in Es • Mergering remnants; gaseous morphology • MHI/LB • Gaseous kinematics: For fast-rotating galaxies, gas and stars are co-rotating, closely linked internal; For slow-rotating (rounder and more triaxial) Es, no alignment between gas and stars external accretion (Sarzi et al. 2006).
Summary • We detected an infrared-red core in ~1/4 elliptical galaxies; • Es with infrared-red cores always contain significant dust in the central regions; • The infrared-red core is due to the dust reradiation heated by central AGNs. • We will investigate how the central dust in Es originate from HI contents and gaseous kinematics.