The Nuclear Regions of Nearby Galaxies 2008. 2. 19 Kyungpook National University Yun Hee Lee and Myeong-Gu Park

CONTENTS INTRODUCTION SAMPLE & DATA REDUCTION ANALYSIS CONCLUSIONS INDIVIDUAL GALAXIES CONCLUSIONS

1. INTRODUCTION Importance of the systematic study on nuclear region Galactic center influences on the current nature, the formation and fate of the Milky Way (Lee 2005) Strong connections in extragalaxies: Central black holes - Velocity dispersion - Halo circular velocity - Dark matter halo mass - Light concentration (Ferrarese & Merritt 2000; Bullock et al. 2001; Ferrarese 2002; Graham et al. 2001)

1. INTRODUCTION - offset Nieto et al. 1986 Lauer et al. 1993 0.4 arcsec offset 2.4 arcsec offset Nieto et al. 1986 Lauer et al. 1993

2. SAMPLE & DATA REDUCTION Bright & Nearby galaxies : Messier’s Galaxies(40) HST/WFPC2 – PC : 0.045”/pixel V & I images – color gradient 1. Type (25/40) Elliptical : 8 Spiral : 16 Lenticular : 1 2. Distance : 0.8 ~ 22.4 Mpc

2. SAMPLE & DATA REDUCTION 1. Combine : to remove bad pixels & cosmic rays (STSDAS/wfpc/combine) 2. Normalize (Dolphin 2000) 3. Correct the geometric distortion (IRAF/digiphot/daofind) : 0.02 ~ 1.41 pixels

3. ANALYSIS Morphology Centroid Surface photometry Color Map Kent(1983)/Jedrzejewsk(1987) Stsdas/isophote/ellipse Color Map IRAF/imutil/imarith,imfunction Surface Brightness Profile γ≡ - dlogI/dlogr γ < 0.3 : core galaxy γ > 0.5 : power-law galaxy 0.3 < γ < 0.5 : intermediate (Lauer et al. 2005) Centroids (within r~1’’) No offset galaxy < 1 pixel Offset galaxy > 1 pixel

3. ANALYSIS Core: 18 / Intermediate: 4 / power-law: 5 Offset: 17 / No offset: 8

4. INDIVIDUAL GALAXIES (1)M32 cE2 No offset Slight blue Core size (0.3pc) ~106Mo BH at 0.3pc (van der Marel et al. 1997) Rapid up in P.A /ε A dim red ring

4. INDIVIDUAL GALAXIES (2)M33 Sc Asymmetric properties : Centroids/ Velocity fields (Colin & Athanassoula 1981) Power-law galaxy No offset Blue Supposed, ~10Mo BH binary (Knox et al. 2002) Rapid Slope

4. INDIVIDUAL GALAXIES (3)M51 LINER/ Sc X-shape dust lane (Maran & Kiney 1993) Low-level emission of Hα/radio (Grillmair et al. 1997) Suggested, molecular gas by a jet of ten pc scale and a warped disk of two rings (Matsushita et al. 2007) Core galaxy (7pc) Like M31 1) offset-opposite direction 2) P1 < P2

4. INDIVIDUAL GALAXIES (4)M58 LINER/ Sy1.9/ SAB Symmetric rotation curve (Palacios et al. 1997) Power-law galaxy Offset Blue Dim spiral-like dust feature Small ups and downs

4. INDIVIDUAL GALAXIES (5)M59 108Mo BH (Merrit & Ferrarese 2001) Two-component structure (Bender 1988) Asymmetry: velocity dispersion (Bender 1990) 60pc KDC (Wernli et al. 2002) Intermediate galaxy No offset Rapid up / transition Red region near core

4. INDIVIDUAL GALAXIES (6)M85 SA Resemble M31 : double nuclei Central minimum Asymmetry Twisted (Lauer et al. 2005) Recent merger candidates (Schweizer & Seitzer 1992) Boxy structure/ KDC (McDermid et al. 2006) A bit central minimum Core galaxy (20pc) Offset Slightly blue Small ups and downs Polar colors

4. INDIVIDUAL GALAXIES (7)M86 S0/E3 Gravitational interaction with neighboring galaxies Asymmetry : X-ray, FIR, Optical (Manfred Stickel 2003) KDC (Bender 1988) Central minimum : 0.07mag (Lauer et al. 2002) Core galaxy (80pc) Nearly no offset

4. INDIVIDUAL GALAXIES (8)M89 LINER/Sy2/ E Ram pressure stripping by galaxy gas (Machacek et al. 2006) MAS core radio source Pc-scale extension structures (Nagar et al. 2002) ~108Mo BH (Filho et al. 2004) Core galaxy (30pc) Offset Spiked peak Rapid up Red region

4. INDIVIDUAL GALAXIES (9)M98 Sy/ SAB Double peaks : 0’’.25 (20pc) Core galaxy (20pc) Offset Red Rapid up/ small up Line connecting the peaks // Major axis of the whole galaxy

4. INDIVIDUAL GALAXIES (10)M104 LINER/Sy1.9/SA Sombrero/ multi-component structure Pointlike source (Crane et al. 1993) ~109Mo BH (Kormendy et al. 1996) Core galaxy (50pc)/ not flat Offset/ A lopsided peak Slightly red Extended red region

5. CONCLUSIONS The central regions are tangled with various phenomena. Most galaxies are offset in the most central regions. Central offset phenomena are not coincident with the asymmetry properties of the whole galaxy. The Hubble type seems to influence on the central offset as well as the offset of the whole galaxy. AGN or LINER seem to be associated with the central offset. Multiple nuclei can produce the central offset.

5. CONCLUSIONS 3. Multiple peaks of M51 and M98 seem to be significant physically. 4. All surface photometry results seem to be meaningful. Existence of SMBH : rapid peak in P.A and ε Multiple peaks : ups and downs in P.A and ε The border line of KDC : transition in P.A and ε 5. Observations of the center of nearby galaxies with high resolution are needed.