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Central Stellar Mass Deficits of Early-Type Galaxies

This study explores the distinction between core-Sérsic and Sérsic galaxies in the context of early-type galaxies, focusing on their structural and morphological properties. The formation mechanisms and environments for S0s with depleted cores are also examined.

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Central Stellar Mass Deficits of Early-Type Galaxies

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  1. Central Stellar Mass Deficits of Early-Type Galaxies Bililign T. Dullo Swinburne University of Technology (Alister W. Graham) Centre for Astrophysics and Supercomputing NGC 1426 NGC 4291

  2. Two families of Early-type galaxies: Core-Sérsic vs. Sérsic dichotomy • Intermediate mass galaxies with • MB ≥-20.5 mag (Sérsic) • Giant galaxies with • MB ≤ -20.5 mag (core-Sérsic, cS) Core-Sérsic light excess light deficit - depleted cores are signatures left by coalescing SMBH binaries (e.g., Begelman et al. 1980; Ebisuzaki et al. 1991; Merritt 2006) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  3. Two families of Early-type galaxies: Core-Sérsic vs. Sérsic dichotomy • Giant galaxies (core-Sérsic) • Intermediate mass galaxies (Sérsic) • - luminous (MB < -20.5 mag) • - stellar light deficits created by • decaying SMBH binary • (e.g., Begelman et al. 1980) • - slow (or no) rotation • - tend to show boxy isophotes • dynamics supported by anisotropy • in velocity dispersion - less luminous (MB > -20.5 mag) - light excess (starburst) - fast rotators - have disky isophotes - isotropic and rotationally supported (Cappellari’s talk) Why are these two systems so different? Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  4. Two families of Early-type galaxies: Core-Sérsic vs Sérsic dichotomy • Giant galaxies (core-Sérsic) • Intermediate mass galaxies (Sérsic) • - luminous (MB < -20.5 mag) • - stellar light deficits created by • decaying SMBH binary • (e.g., Begelman et al. 1980) • - slow (or no) rotation • - tend to show boxy isophotes • dynamics supported by anisotropy • in velocity dispersion - less luminous (MB > -20.5 mag) - light excess (starburst) - fast rotators - have disky isophotes - isotropic and rotationally supported - last mergers were ‘dry’- last mergers were gas-rich Structure and Morphology in the Era of Large Surveys, Santiago, Chile 4

  5. Evolution of SMBH Binaries Post major (‘dry’) merger scenario Phase I: Dynamical friction (binary separation decays) Phase II: Three-body interaction (Ejects stars) Depleted mass ∝ mass of the binary (e.g., Ebisuzaki et al. 1991; Merritt 2006) ? last parsec problem Phase III: Anisotropic gravitational radiation (Coalescence ensues, and SMBH recoils) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  6. Core-Sérsic model fits to luminous early-type galaxies - HST (WFPC2/ACS) data - 31 core-Sérsic galaxies (26 Es + 5 S0s) Es - median Δ for the 31 cS galaxies ≈ 0.045 mag arcsec-2 S0s

  7. Central stellar mass deficits (Mdef) of luminous galaxies NGC 4382 Ldef Ldef – the difference in luminosity between the Sérsic model and the core-Sérsic model - Ldef converted into Mdef using stellar M/L ratios obtained from the color-age-metallicity-(M/L) diagram by Graham & Spitler (2009) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  8. Mdef –MBH relation and galaxy merger history Mdef ~ (0.5 – 4) MBH (e.g., Graham 2004; Ferrarese+2006) Mdef/MBH≃0.5 –1per major merger (N-body simulations by Merritt 2006, Phase II) - core formation is a cumulative process a few (1 to 8) major mergers - consistent with observations (0.5 – 2 mergers since z~1, e.g., Bell+2006; Bluck+2012, Conselice’s talk) and theories (Haehnelt & Kauffmann 2002) - Mdef/MBH ≥ 4 may be due to recoiled SMBHs, Phase II +III - predicted black hole masses (MBH) obtained using the Graham & Scott (2013) non-barred M-σ relation - two dynamically determined BH masses for NGC 1399 (Houghton+2006; Gebhardt+2007) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  9. Core-Sérsic bulge + exponential disk fits to 4 luminous S0s Mdef ~ (0.5 – 2) MBH, for S0s (Dullo & Graham 2013)

  10. Formation origin for luminous S0s Core-Sérsic lenticular galaxies have undergone violent major merger/s Main question: how do these galaxies have disks? Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  11. Formation mechanism(s) for S0s with depleted cores / Environment • Popular mechanisms Ram pressure stripping (Gunn & Gott 1972) - hot intra-cluster medium removes gas from moving galaxy Harassment (Moore et al. 1996) - frequent, close high-velocity encounters - interaction with the cluster potential Strangulation (Larson 1980) - gas supply is cut off, cold gas exhausted through star formation • Environment - NGC 507, NGC 2300 and NGC 5813 reside in galaxy groups - NGC 6849 is an isolated galaxy - NGC 4382 is a member of the Virgo cluster, situated at the outskirt Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  12. Formation mechanism(s) for S0s with depleted cores / Environment (Dullo & Graham 2013) Two stage galaxy assembly: early violent `dry’ merger (bulge) followed by late accretion of gas and stars (disk) (e.g., Steinmetz & Navarro 2002; Birnboim & Dekel 2003; Arnold et al. 2011) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  13. Compact high redshift (z~2) galaxies vs. local disk bulges Bulges of our core-Sersic S0s are - red - compact Re ≤ 2 kpc - massive, M*~1011 M Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  14. Compact high redshift (z~2) galaxies vs. local disk bulges Virgo elliptical galaxy M87 Compact galaxy at z =1.6 (van der Wel+ 2011) • Compact, quiescent and dense galaxies at z ~2 (Daddi+2005; Trujillo+2006) - Re < 2 kpc and stellar mass M*~1011 M - a factor of 2 to 5 smaller than today’s ellipticals of comparable stellar mass -minor mergers - major mergers - adiabatic expansion ? ?There aren’t enough satellite galaxies around (Trujillo 2013) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  15. Compact high redshift galaxies vs. local disk bulges Compact high redshift galaxies from Damjanov et al. (2009) Graham (2011-2013) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  16. From compact high redshift galaxies to bulges of today’s S0s (Dullo & Graham 2013, high-z galaxies were taken from Damjanov et al. 2011) Bulges of local massive S0s may be modern day counterparts to compact high-z galaxies Two stage galaxy assembly: early violent `dry’ merger (bulge, i.e., compact high-z galaxy) followed by late accretion of gas and stars (disk) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  17. Conclusions • We measure central stellar mass deficits (Mdef) in core-Sérsic galaxies which are 0.5 – 4 MBH. The Mdef – MBH correlation is a physical signature connecting SMBHs to their host galaxies. • The depleted cores/stellar mass deficits (0.5 – 2 MBH) in core-Sérsic lenticular galaxies suggest a two-step inside-out scenario for their assembly. • Today’s massive bulges may be local analogs to compact high redshift early-type galaxies. Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  18. Thank you

  19. Core-Sersiclenticular galaxies Core-Sersic galaxies are believed to have undergone major mergers NGC 4382 NGC 2300 It is assumed that major mergers destroy disks NGC 507, NGC 2300, NGC 3607, NGC 3706, NGC 4382 and NGC 6849 - Bias subtraction - Geometric distortion correction - Dark current subtraction - flat fielding - Sky subtraction - taken from the (public) Hubble Legacy Archive (HLA) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  20. Literature results

  21. Core detection b) a) NGC 4291 NGC 1426 HST/WFPC2 images Core-Sersic Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  22. Environment Isolated | Groups | Cluster Morphology-Density Relation (Dressler 1980) S S0 E Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  23. Environment NGC 507, NGC 2300 and NGC 3607 reside in X-ray bright galaxy groups Galaxy merger (Toomre & Toomre 1972) NGC 6849 is an isolated galaxy - isolated early-type galaxies have merger related origin (Reda et al. 2004 and Arnold et al. 2011, NGC 3115) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  24. Structural parameter relations Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  25. Core-Serisc model Sersic model Structure and Morphology in the Era of Large Surveys, Santiago, Chile

  26. (Komossa et al. 2003)

  27. - majority of compact high redshift galaxies have small undeveloped disks (van der Wel et al. 2011)

  28. Alternative core formation mechanisms • Disipationless collapses in preexisting dark matter haloes (Nipoti et al. 2006) • Sinking massive objects, 3kpc (Goerdt et al. 2010) • AGN feedback + inspiraling massive black holes, 8 -10 kpc(Martizzi et al. 2012) Structure and Morphology in the Era of Large Surveys, Santiago, Chile

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