Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology

Constraining dark matter halo Constraining dark matter halo profiles and galaxy formation models profiles and galaxy formation models

using spiral arm morphologyusing spiral arm morphology

Marc Seigar

Dec 4th ESO, Santiago

Dec 4th, ESO

Collaborators:

• Aaron Barth (UC Irvine)

• James Bullock (UC Irvine)

• Luis Ho (OCIW)

David Block (Wits), Ivanio Puerari (INAOE), Phil James (Liverpool)

Dec 4th, ESO

Outline

• Spiral galaxy morphology

• Shear versus spiral arm morphology

• Constraining dark matter profiles

• The mass profile of M31

• Nuclear spiral structure

• Carnegie-Irvine Nearby Galaxy Survey (CINGS)

Dec 4th, ESO

Why are we interested in DM halo profiles?

Profiles of DM halos are sensitive to our cosmological models:

• CDM predicts cuspy centers for density profiles for all galaxy halos - from DM simulations (Navarro, Frenk & White 1997; Navarro et al. 2004; Diemand et al. 2005)

• WDM predicts that galaxies can have constant density cores (Zentner & Bullock 2003)

• Galaxies with constant density cores may be biased due to late formation (e.g. Wechsler et al. 2002)

Dec 4th, ESO

Spiral Density Waves

Lin & Shu (1964, 1966), Bertin et al. (1989a, b), Bertin & Lin (1996), Fuchs (1991, 2000)

Spiral structure is described as a quasi-stationary density wave.

Predict that large central mass concentrations result in tighter wound spiral structure.

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Spiral galaxy morphology

• Near-IR versus optical morphology:

Weak correlation found between near-IR morphology and Hubble classification (Seigar & James 1998; de Jong 1996)

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Spiral galaxy morphology

• Near-IR versus optical morphology:

Even the correlation between spiral arm pitch angle and Hubble type is weak (Kennicutt 1981; Seigar & James 1998)

Optical

Kennicutt (1981) Seigar & James (1998)

Dec 4th, ESO

Spiral galaxy morphology

• Near-IR versus optical morphology:

Near-IR imaging can sometimes reveal grand-design spiral structure in galaxies that appear flocculent in the optical (Seigar et al. 2003; Thornley 1996)

Thornley (1996)

Dec 4th, ESO

Spiral structure and the connection with shear

Galaxies with flat rotation curves have S=0.5

Galaxies with falling rotation curves have S>0.5

Galaxies with rising rotation curves have S<0.5

Block et al. (1999) show a hint of a correlation between shear and spiral arm pitch angle

Dec 4th, ESO

Seigar et al. (2005)

NGC 7677

SABbc; P=17.0±0.8; S=0.66±0.02

Dec 4th, ESO

Seigar et al. (2005)

ESO 576-G12

SBbc; P=30.4±1.9; S=0.47±0.04

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Seigar et al. (2005)

NGC 3456

SBc; P=38.0±0.6; S=0.31±0.02

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Seigar et al. (2005)

Pitch angle versus rotation curve type

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Seigar et al. (2005)

Pitch angle versus shear rate

From near-IR imaging

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Seigar et al. (2006)

Near-IR pitch angle versus Optical pitch angle

NGC 613

Dec 4th, ESO

Seigar et al. (2006)

Pitch angle versus shear including B band data

Dec 4th, ESO

Constraining central mass concentrations

• The correlation between shear and pitch angle

implies that mass concentration plays a role in determining how tightly wound spiral arms are.

• Use different mass profile models to reproduce the measured shear.

pure NFW

adiabatically contracted NFW

Dec 4th, ESO

• Standard framework of disk galaxy formation: Fall & Efstathiou (1980); Blumenthal et al. (1986)

• Baryons and DM initially follow an NFW profile.

Adiabatic contraction

rs is a scale radius, c is a dimensionless characteristic density and crit=3H2/8G (critical density)

Navarro, Frenk & White (1997)

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Adiabatic contraction

• Baryons are allowed to cool. They cool slowly (c.f. typical orbital time) and settle into the center to form a stellar disk halo contraction.

• Adiabatic contraction (AC). Accurately describes disk galaxy formation in numerical simulations (e.g. Gnedin et al. 2004)

Dec 4th, ESO

Adiabatic contraction models

• We use the AC model of Bullock et al. (2001) - AC model

• We also use a model with no adiabatic contraction, which is a small modification, where the contraction is simply turned off - non-AC model.

• Non-AC model. In this case the DM halo masses and density profiles do not respond significantly to the formation of a disk galaxy Pure NFW.

• Test these models using max. rotation velocity and measured shear (related to slope of rotation curve).

Dec 4th, ESO

Two example galaxies

ESO 582-G12

Flat rotation curve; S=0.52±0.05

middle of range

IC 2522

Rising rotation curve; S=0.39±0.02

towards low end of range

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1-D bulge-disk decomposition

Seigar et al (2006)

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1-D bulge-disk decomposition

• ESO 582-G12

h=5.48±0.57 kpc

B/D=0.11

Ldisk=(1.27±0.11)x1010 L

• IC 2522

h=3.98±0.41 kpc

B/D=0.16

Ldisk=(1.55±0.14)x1010 L

Seigar et al. (2006)

Dec 4th, ESO

Inputs to the models:

• V2.2, the velocity at 2.2 disk scalelengths.

• Disk scalelength, h, in kpc.

• Disk mass, calculated using the disk luminosity and a range of M/L ratios, 1.0, 1.3 and 1.6 (in B band solar units) from Bell & de Jong (2001).

• B/D ratio.

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ESO 582-G12

Seigar et al. (2006)

Cvir=17 - 31 Fbar=0.18 - 0.41

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ESO 582-G12 cont…

Seigar et al. (2006)

Mvir=5 - 8x1011 M

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IC 2522

Seigar et al. (2006)

Cvir< 8 Fbar< 0.1

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IC 2522 cont…

Seigar et al. (2006)

Mvir=1 - 6x1012 M

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ESO 582-G12 Mass Concentrations

Seigar et al. (2006)

Ctot=0.13 - 0.24 CDM=0.09 - 0.16

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IC 2522 Mass Concentrations

Seigar et al. (2006)

Ctot<0.04 CDM<0.02

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Rotation Curves

Seigar et al. (2006)

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The spiral pattern in M31

Seigar, Barth & Bullock (2006, ApJ, submitted)

P=24.7±4.4

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M31

Cvir < 14 Fbar=0.35-0.85

Klypin et al. (2002) found c=12

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M31

Mvir=7.0-13.0x1011 M

From satellite kinematics and the Andromeda Stream:

Mvir~8-9x1011 M

Geehan et al. (2006)

Chapman et al. (2006)

Fardal et al. (2006)

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M31 mass concentrations

Ctot=0.10-0.24 CDM=0.04-0.11

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The mass profile of M31

Seigar, Barth & Bullock (2006, ApJ, submitted)

Needs AC (see also Klypin et al. 2002).

Best fitting model includes a B86 type AC halo.

Baryonic mass determined from the 2MASS K-band image and B-R color profile of Walterbos & Kennicutt (1987)

Dec 4th, ESO

The mass profile of M31

Seigar, Barth & Bullock (2006, ApJ, submitted)

Mvir=(8.7±0.7)x1011 M

Andromeda Stream and satellite galaxy kinematics gives:

Mvir~8x1011 M

Dec 4th, ESO

Summary

• Optical and near-infrared spiral arm pitch angles are similar.

• There is a strong correlation between shear and spiral arm pitch angle.

• This allows us to constrain disk galaxy mass profiles.

• IC 2522 - adiabatic contraction is ruled out.

• ESO 582-G12 - adiabatic contraction is possible.

Dec 4th, ESO

Summary

• Our modeling predicts that IC 2522 and ESO 582-G12 have halo masses that are different by an order of magnitude, even though the characteristics of their stellar disks/bulges seem very similar.

• M31 - The best fitting mass model of M31 requires adiabatic contraction. It also agrees well with other mass estimates of, e.g., the halo virial mass.

Dec 4th, ESO

What next?

We have outlined a method for constraining dark matter profiles and disk galaxy formation models, using only three galaxies so far.

There are 150 - 200 galaxies in the Carnegie-Irvine Nearby Galaxy Survey (CINGS; PI: Ho) for which pitch angles can be measured and the same method applied.

Application to disk galaxies in deep HST fields (e.g. Groth strip/DEEP2 survey or GOODS fields).

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Some galaxies in the GOODS-S field

A possible method to investigate evolution in mass concentrations and profile shapes.

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Nuclear spirals• Maciejewski (2004a, b) - nuclear spirals can be used to investigate mass concentrations on sub-kpc scales.

Constant density core

Central SMBH

Central density cusp

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Nuclear spirals• Basis of an approved cycle 15 HST archival proposal

NGC 1530 has a nuclear spiral that seems to wind up within 60 pc - SMBH

NGC 3362 has spiral structure that can be traced to within 120 pc - constant density core

NGC 5427 - constant density core within 200 pc

Dec 4th, ESO

Carnegie-Irvine Nearby Galaxy SurveyBVRIKs imaging survey of the 603 brightest southern hemisphere galaxies (BT<12.9).

Optical imaging is complete, near-IR imaging of 220 galaxies so far.

Goals: 1-D and 2-D decomposition of galaxies with bulge, disk, bar and spiral arm components, with a new version of GALFIT (Peng 2006).

Immediate objectives: 1-D modeling of surface brightness profiles and color profiles - test the ideas of Secular evolution, where late-type spirals have (pseudo)-bulges that have properties resembling those of disks. The outer shapes of the profiles?

Dec 4th, ESO

Carnegie-Irvine Nearby Galaxy Survey

http://www.ociw.edu/~lho/projects/CINGS/CINGS.html