1. Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology Marc Seigar Dec 4th ESO, Santiago

2. Dec 4th, ESO Collaborators: Aaron Barth (UC Irvine) James Bullock (UC Irvine) Luis Ho (OCIW) David Block (Wits), Ivanio Puerari (INAOE), Phil James (Liverpool)

3. 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)

4. 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)

5. 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.

6. Dec 4th, ESO Spiral galaxy morphology Near-IR versus optical morphology: Weak correlation found between near-IR morphology and Hubble classification (Seigar & James 1998; de Jong 1996)

7. Dec 4th, ESO 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)

8. 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)

9. 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

10. Dec 4th, ESO Seigar et al. (2005) NGC 7677 SABbc; P=17.0±0.8; S=0.66±0.02

11. Dec 4th, ESO Seigar et al. (2005) ESO 576-G12 SBbc; P=30.4±1.9; S=0.47±0.04

12. Dec 4th, ESO Seigar et al. (2005) NGC 3456 SBc; P=38.0±0.6; S=0.31±0.02

13. Dec 4th, ESO Seigar et al. (2005) Pitch angle versus rotation curve type

14. Dec 4th, ESO Seigar et al. (2005) Pitch angle versus shear rate From near-IR imaging

15. Dec 4th, ESO Seigar et al. (2006) Near-IR pitch angle versus Optical pitch angle NGC 613

16. Dec 4th, ESO Seigar et al. (2006) Pitch angle versus shear including B band data

17. 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

18. 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 r s is a scale radius,  c is a dimensionless characteristic density and  crit =3H 2 /8  G (critical density) Navarro, Frenk & White (1997)

19. Dec 4th, ESO 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)

20. 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).

21. 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

22. Dec 4th, ESO 1-D bulge-disk decomposition Seigar et al (2006)

23. Dec 4th, ESO 1-D bulge-disk decomposition ESO 582-G12 h=5.48±0.57 kpc B/D=0.11 L disk =(1.27±0.11)x10 10 L  IC 2522 h=3.98±0.41 kpc B/D=0.16 L disk =(1.55±0.14)x10 10 L  Seigar et al. (2006)

24. Dec 4th, ESO Inputs to the models: V 2.2, 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.

25. Dec 4th, ESO ESO 582-G12 Seigar et al. (2006) C vir =17 - 31 F bar =0.18 - 0.41

26. Dec 4th, ESO ESO 582-G12 cont… Seigar et al. (2006) M vir =5 - 8x10 11 M 

27. Dec 4th, ESO IC 2522 Seigar et al. (2006) C vir < 8 F bar < 0.1

28. Dec 4th, ESO IC 2522 cont… Seigar et al. (2006) M vir =1 - 6x10 12 M 

29. Dec 4th, ESO ESO 582-G12 Mass Concentrations Seigar et al. (2006) C tot =0.13 - 0.24C DM =0.09 - 0.16

30. Dec 4th, ESO IC 2522 Mass Concentrations Seigar et al. (2006) C tot <0.04C DM <0.02

31. Dec 4th, ESO Rotation Curves Seigar et al. (2006)

32. Dec 4th, ESO The spiral pattern in M31 Seigar, Barth & Bullock (2006, ApJ, submitted) P=24.7±4.4

33. Dec 4th, ESO M31 C vir < 14 F bar =0.35-0.85 Klypin et al. (2002) found c=12

34. Dec 4th, ESO M31 M vir =7.0-13.0x10 11 M  From satellite kinematics and the Andromeda Stream: M vir ~8-9x10 11 M  Geehan et al. (2006) Chapman et al. (2006) Fardal et al. (2006)

35. Dec 4th, ESO M31 mass concentrations C tot =0.10-0.24C DM= 0.04-0.11

36. Dec 4th, ESO 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)

37. Dec 4th, ESO The mass profile of M31 Seigar, Barth & Bullock (2006, ApJ, submitted) M vir =(8.7±0.7)x10 11 M  Andromeda Stream and satellite galaxy kinematics gives: M vir ~8x10 11 M 

38. 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.

39. 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.

40. 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).

41. Dec 4th, ESO Some galaxies in the GOODS-S field A possible method to investigate evolution in mass concentrations and profile shapes.

42. Dec 4th, ESO 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

43. Dec 4th, ESO 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

44. Dec 4th, ESO Carnegie-Irvine Nearby Galaxy Survey BVRIK s imaging survey of the 603 brightest southern hemisphere galaxies (B T <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?

45. Dec 4th, ESO Carnegie-Irvine Nearby Galaxy Survey http://www.ociw.edu/~lho/projects/CINGS/CINGS.html