Bililign T. Dullo Swinburne University of Technology

(Alister W. Graham)

Centre for Astrophysics and Supercomputing

NGC 4291 NGC 1426

Core-Sérsic

Giant galaxies with MB ≤ -20.5 mag (core-Sérsic, cS)

Intermediate mass galaxies with MB ≥ -20.5 mag (Sérsic)

- depleted cores are signatures left by coalescing SMBH binaries (e.g., Begelman et al. 1980; Ebisuzaki et al. 1991; Merritt 2006)

Two families of Early-type galaxies: Core-Sérsic vs. Sérsic dichotomy

light deficitlight excess

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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 anisotropyin velocity dispersion

- less luminous (MB > -20.5 mag) - light excess (starburst)

- fast rotators - have disky isophotes - isotropic and rotationally supported

Why are these two systems so different?

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(Cappellari’s talk)

Two families of Early-type galaxies: Core-Sérsic vs Sérsic dichotomy

4

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 anisotropyin 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

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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)

Phase III: Anisotropic gravitational radiation(Coalescence ensues, and SMBH recoils)

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Core-Sérsic model fits to luminous early-type galaxies

Es

S0s

- HST (WFPC2/ACS) data

- 31 core-Sérsic galaxies (26 Es + 5 S0s)

- median Δ for the 31 cS galaxies ≈ 0.045 mag arcsec-2

Central stellar mass deficits (Mdef) of luminous galaxies

- Ldef converted into Mdef using stellar M/L ratios obtained from the color-age-metallicity-(M/L) diagram by Graham & Spitler (2009)

Ldef

Ldef – the difference in luminosity between the Sérsic model and the core-Sérsic model

NGC 4382

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Mdef/MBH ≃ 0.5 –1 per major merger (N-body simulations by Merritt 2006, Phase II)

Mdef –MBH relation and galaxy merger history

- core formation is a cumulative process

Mdef ~ (0.5 – 4) MBH

(e.g., Graham 2004; Ferrarese+2006)

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)

- 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)

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- Mdef/MBH ≥ 4 may be due to recoiled SMBHs, Phase II +III

Core-Sérsic bulge + exponential disk fits to 4 luminous S0s

(Dullo & Graham 2013)

Mdef ~ (0.5 – 2) MBH, for S0s

Formation origin for luminous S0s

Core-Sérsic lenticular galaxies have undergone violent major merger/s

Main question: how do these

galaxies have disks?

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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

Formation mechanism(s) for S0s with depleted cores / 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

Popular mechanisms

Environment

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Ram-pressure stripping ✗

Harassment ✗

Strangulation ✗

Major dry merger + (subsequent cold gas accretion)

✔

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)

Formation mechanism(s) for S0s with depleted cores / Environment

(Dullo & Graham 2013)

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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

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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

Compact high redshift (z~2) galaxies vs. local disk bulges

Compact galaxy at z =1.6 (van der Wel+ 2011)

Virgo elliptical galaxy M87

- minor mergers - major mergers- adiabatic expansion

? There aren’t enough satellite galaxies around (Trujillo 2013)

?

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Graham (2011-2013)

Compact high redshift galaxies vs. local disk bulges

Compact high redshift galaxies from Damjanov et al. (2009)

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From compact high redshift galaxies to bulges of today’s S0s

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)

(Dullo & Graham 2013, high-z galaxies were taken from Damjanov et al. 2011)

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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.

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Thank you

Core-Sersic lenticular galaxies

NGC 2300NGC 4382

NGC 507, NGC 2300, NGC 3607, NGC 3706, NGC 4382 and NGC 6849

- taken from the (public) Hubble Legacy Archive (HLA)

Core-Sersic galaxies are believed to have undergone major mergers

It is assumed that major mergers destroy disks

- Bias subtraction - Geometric distortion correction- Dark current subtraction- flat fielding - Sky subtraction

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Study Model Mdef/MBH

Faber et al. (1997) Nuker ~ 4 - 7

Milosavljevic & Merritt (2001)) Nuker ~ 1 - 20

Ravindranath, Ho, & Filippenko (2002) Nuker ~ 2 - 25

Graham (2004) Core-Sersic ~ 1 - 4

Ferrarese et al. (2006) Core-Sersic ~ 1 - 4

Lauer et al. (2007) Nuker Up to 19

Hyde et al. (2008) Core-Sersic ~ 2

Kormendy et al. (2009) Sersic ~ 5 - 20

Dullo & Graham (2012) Core-Sersic ~ 0.5 - 4

Dullo & Graham (2012) (submitted) Core-Seisic ~ 0.5 - 2

Literature results

Core-Sersic

Core detection H

ST/W

FPC

2

imag

esNGC 4291 NGC 1426a) b)

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Environment

Morphology-Density Relation (Dressler 1980)

S

S0

E

Isolated | Groups | Cluster

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Galaxy merger (Toomre & Toomre 1972)

NGC 507, NGC 2300 and NGC 3607 reside in X-ray bright galaxy groups

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)

Environment

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Structural parameter relations

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Core-Serisc model

Sersic model

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(Komossa et al. 2003) 19/11/201326

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

Alternative core formation mechanisms

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