The formation of large galactic disks: revival or survival?

Intermediate Mass Galaxy Evolution Sequence

by François Hammer

Coll: H. Flores, M. Puech, R. Delgado-Serrano, B. Neichel, S. Peirani, M. Rodrigues, Y. Yang, J. Wang, S. Fouquet, P. Amram, E. Athanassoula, C. Balkowski, B. Epinat, I. Fuentes-Carrera, Y. Liang

The formation of large galactic disks: revival or survival?

Spiral disk - rotating

Irregular - rotating Compact - complex Minor merger - perturbed Compact - complex Merger - complex

28th September 2011 1

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M 31 NGC 2997 NGC 1313

M83 M100 SABbc NGC 1365


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Thin disks are fragile to collisions

Mergers with other galaxies can easily destroy thin disks (e.g. Toth & Ostriker, 1992)


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Angular momentum acquired from galaxy interactions at earliest epochs;

Disks are then assumed to evolve without subsequent major mergers Spirals are assumed to be similar to the Milky Way so called “secular” scenario


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Excerpt from Dekel, Paris courses, 2006 28th September 2011

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What is the past history of giant spiral

galaxies?

Their progenitors are within distant galaxies


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Sample selection MJ(AB) < -20.3 & 0.4 < z < 0.9

4 fields including CDFS

Imaging ACS imagery (≥ 3 orbits)

3D Spectroscopy VLT/FLAMES-GIRAFFE

(R=9000, 8-24hrs exposure)

Spitzer VLT/FORS2 (600RI+600z)

(≥ 3 hrs each)

Intermediate-mass galaxies Mstellar > 1.5 1010Mʘ

(average ~M*, e.g. MW)

SFR Metallicity of the gas (O/H)

Color-morphology comparable to SDSS (depth, resolution)

Spatially resolved kinematics Large scale dynamics

The IMAGES Survey: provides us with a complete description of galaxy properties, 6 Gyr ago


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Classification based on similarities with local galaxies Semi-automatic decision tree: GALFIT + Colour maps + Visual inspection

Morphological classification: semi-automatic decision tree


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• Delgado-Serrano et al, 2010, A&A, 509, 78 • Neichel et al. 2008, A&A, 484, 159 • also Zheng et al. 2005, 2006

MJ(AB) < -20.3

~ Mstellar > 1.5 1010Mʘ

Morphological fractions in agreement

with van den Bergh (2002)

MJ(AB) < -20.3


Delgado-Serrano et al. 2010,A&A, 509, 78


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Today: z=0

6 Gyrs ago: z=0.65

80% of Rotating galaxies have spiral morphologies

95% of Complex Kinematics have peculiar morphologies

Agreement between spatially-resolved kinematics and morphological classifications

Anomalous kinematics of the gaseous component is linked to anomalous morphological distribution of the stars


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Neichel et al (2008, A&A 484, 159)

86% of Perturbed Rotation have peculiar morphologies

Sp Peculiar Comp Merg

# R

otat

ing

# Pe

rturb

ed

# C

ompl

ex

80% of Rotating galaxies have spiral morphologies

95% of Complex Kinematics have peculiar morphologies

Disagreement between spatially-resolved kinematics and automatic classification

Automatic classifications (ACS, GINI-M20) overestimate by a factor ~2 the fraction of spirals at z~ 0.6


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Neichel et al (2008, A&A 484, 159)

86% of Perturbed Rotation have peculiar morphologies

# R

otat

ing

# Pe

rturb

ed

# C

ompl

ex

Sp Peculiar Comp Merg

MJ(AB) < -20.3


Today: z=0

6 Gyrs ago, z=0.65:

Delgado-Serrano et al. 2010,A&A, 509, 78

• E/S0 were mostly in place

• half of spirals did not

they had peculiar morphologies

and anomalous kinematics

Spirals: 72%

Peculiars: 52% Spirals: 31% 28th September 2011

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Associating Morpho-kinematics with physical processes

COLD STREAMS

CLUMP FRAGMENT.

MAJOR MERGERS

MINOR MERGERS OUTFLOWS

SECULAR EVOLUTION


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Minor merger? CK galaxies: Morpho-kinematic disturbances are global, not local:

GIRAFFU IFU resolution

~ 7 kpc @ z=0.6

Puech et al. (2007) 28th September 2011

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Outflows: - only a handful of galaxies have significant shifts between abs. and emission lines (Hammer et al. 09; Rodrigues et al., in prep).

Clump fragmentation & cold flows: - only 20% of anomalous galaxies are clumpy (Puech, 2010) - cold gas accretion tends to vanish in massive halos at z<1 (<1.5 Mo/yr at z~0.6 see Keres et al. 2009, Brooks et al. 2009)

Secular evolution: Kinematic perturbations are too strong and extended


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COLD STREAMS

CLUMP FRAGMENT.

MAJOR MERGERS

MINOR MERGERS OUTFLOWS

SECULAR EVOLUTION


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Peculiar morphologies & anomalous kinematics can be reproduced by major mergers


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Hammer et al. 2009, Astronomy & Astrophysics, 507, 1313

Example (Yang et al. 2009, Peirani et al. 2009): the fitting process is over determined

A giant bar induced by a merger

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VF observed σ observed

VF simulated σ simulated

See Fuentes-Carrera et al. 2010, A&A, 513, 43

A novel channel to form large disks: rebuilding disks after gas-rich mergers


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The orbital angular momentum from major mergers may solve the spin “catastrophe” (Maller, Dekel & Somerville, 2002)

Mass ratio

Hopkins et al 2010 Rodrigues et al. 2011

Gas

frac

tion

(%)

Lookback time (Gyr)

Expectations from theory Excerpt from Lia Athanassoula, in Granada, 2009


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What about nearby spirals?

Many simulations report the formation of late-type disk after major mergers (Font+11, Brook+11, Keres

+11 etc…)


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Van den Bergh (2003): «It is suggested that M31 was created by the early merger of two massive galaxies »


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First passage ~ 8.5 Gyr ago, fusion ~ 5.5 Gyr ago

GADGET2, 8M particles

The tumultuous history of nearby spirals (Martinez-Delgado et al. 2008, 2009)

NGC 5907 NGC 4013

M 63

Simulations from Font et al. 2006 Minor or major mergers?


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NGC 5907 NGC 4013

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The tumultuous history of nearby spirals (Wang et al. , 2011, A&A submitted)


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NGC 5907 NGC 4013

M 63



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- B/T=0.17 - Thick disk comparable to IRAC 3.6 µm observations



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- B/T=0.17 - Thick disk comparable to IRAC 3.6 µm observations - Residuals surrounding the disk are affected by dust (~2 mag at 5kpc)

NGC 5907 NGC 4013

M 63

Discussion – Conclusions


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• Half of the progenitors of spirals, 6Gyr ago have peculiar morphologies & kinematics ==> excluded from the Hubble Sequence classification

• Half of the progenitors of spirals, 6 Gyr ago are found at different phases of a merger process Is that a too large fraction?

• No, this is because morpho-kinematics analysis ‘a la ‘ IMAGES are sensitive to all the merger phases (pre to post-fusion)

• The deduced merger rate is in good agreement with ΛCDM predictions (Puech, Hammer, Hopkins, Athanassoula, Flores et al, 2011, in prep.)

• This alleviates the disk survival issue and the angular momentum ‘catastrophe’and the hierarchical scenario may apply to both spiral & elliptical galaxies

Documents

The formation of large galactic disks: revival or survival?