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.All galaxies contain supermassive black holes. The mass of SMBH is tightly correlated with the mass of the bulge.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 (1) An S-shape velocity curve with a peak amplitude of 400 km s -1 at 0.1”(8 pc) from the nucleus. (2) 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. (3) A nuclear compact mass of 1.5×10 9 M ⊙ with an uncertainty of ( )10 9 M ⊙

Es: QSOs’ hosts at high z Radio-Loud QSOs –Exclusively in elliptical hosts Radio-Quiet QSOs –M B <-24: 100% in bulge-dominant hosts –-21<M B <-24: 55%“ –M B <-21 (Sy1): 30% “ Floyd D. et al. 2004, MNRAS, 355, 196

SMBHs in local Ellipticals In the Palomar sample, 57 EsIn the Palomar sample, 57 Es 26 with pure absorption nuclei 26 with pure absorption nuclei 4 Seyferts + 21 LINERs + 6 Transition 4 Seyferts + 21 LINERs + 6 Transition

● 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) Spitzer: Powerful IR Telescope

Wilson et al. (2006): at z ~1, 1/3 EROs are detected at 24 um;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.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.EROs: Counterparts and progenitors of local massive E and S0 galaxies.Motivation

Motivation Wilson et al. 2006

K s image with 24  m 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 find the infrared indicator of SMBH activities in local elliptical galaxies; To understand the origin of infrared emission in elliptical galaxies.To understand the origin of infrared emission in elliptical galaxies. All Es in Ho’s sample with Spitzer IRAC observations.All Es in Ho’s sample with Spitzer IRAC observations. We detected infrared-red cores in 6(24) EsWe detected infrared-red cores in 6(24) Es

One example: NGC 315

IRAC Color Distributions

4.5um-3.6um5.8um-3.6um 8.0um-3.6um24um After removing stellar population …

NGC 315

Another example: NGC 5322

What is behind ? The strength of SMBHs activities ? The dust mass ? IR emission mechanism: dust reradiation optical-UV-soft X-ray photons (AGNs/Starburst) --- dust --- infrared

Emission Line

Hubble WFPC2 image of NGC 315 Central Dust Structures

Hubble WFPC2 image of NGC 4374 Central Dust Structures

Hubble WFPC2 image of NGC 4278 Hubble WFPC2 image of NGC 5322 Adopt from Lauer et al., 2005, AJ, 129, 2138

NGC 5077 Exception: Central Dust

NGC 4125NGC 4552 NGC 7626 NGC 5813 Elliptical Galaxies without an Infrared-red Core

Origin of Dust in Es Internal origin : stellar mass lossInternal origin : stellar mass loss External origin: minor merger of small gas-rich satelliate system (Indications: off-set clouds, polar discs)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 M HI /L B 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.

AGNs ’ Host Galaxies

Schade et al. 2000