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The morphological dependent Tully-Fisher relation of spiral galaxies

The morphological dependent Tully-Fisher relation of spiral galaxies. Shiyin Shen Collabroators: Ruixiang Chang, Jinliang Hou Shanghai Astronomical Observatory Kunming, 2/23/2009. Introduction.

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The morphological dependent Tully-Fisher relation of spiral galaxies

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  1. The morphological dependent Tully-Fisher relation of spiral galaxies Shiyin Shen Collabroators: Ruixiang Chang, Jinliang Hou Shanghai Astronomical Observatory Kunming, 2/23/2009

  2. Introduction • Tully-Fisher (TF) relation: correlation between the maximum rotation velocity and absolute magnitude (Tully & Fisher 1977) • M = a Log Vmax + b • small scatter, rms ~ 0.3 mag at near infrared band • distance estimator: Hubble constant • Morphological type of spiral galaxies • Hubble system: Sa/Sb/Sc/Sd/Irr • RC3 system: T: 0  10 S0  Irr • From early to late type • Smaller relative bulge size • Larger pitch angle of spirals • Coupled with spiral luminosity: earlier type galaxies are biased to brighter galaxies 8th Sino-German Workshop

  3. Morphological dependence of TF relation • Discovered by Roberts (1978), confirmed by Rubin (1985) • for samples of the same absolute magnitude, late-type galaxies have systematically smaller intrinsic line widths than early-type systems (Roberts, 1978). • At given Vmax , a Sa galaxy is 2 mag fainter in B band and 1 mag fainter in H band than typical Sc galaxy (Rubin, 1985) • In I band • Giovanelli et al. (1997) found a 0.32 mag smaller zero point for Sa/Sab galaxies and 0.10 mag smaller for Sb galaxies relative to Sbc and later type spirals.(555 spirals) • Russel(2004) found Sb galaxies have a zero point 0.57 mag smaller than Sc galaxies in B band . 8th Sino-German Workshop

  4. Morphological dependence: further dependent on luminosity • SFI++ sample: ~5000 spiral galaxies suitable for TF study in I band (Masters et al. 2006) • morphological dependence: further on magnitudes • Sa to Sc: -0.32-0.9(logW-2.5)mag • Sb to Sc: -0.1-0.9(logW-2.5) mag • Morphological dependence is more pronounced for more massive galaxies 8th Sino-German Workshop

  5. Morphological dependence: K-band (Russell, 2008) • Compare the mean TF distances of the clusters and groups when using ScI galaxies and Sb galaxies • Calibrated by Cepheid distance • Mean difference: 0.19mag • Effects from dynamics (Vmax) or stellar population (M)? 8th Sino-German Workshop

  6. Type dependence: dynamics • Early type spirals with large bulges have rotation curves that rise more rapidly than late type spirals with similar L (Corradi & Capaccioli 1990) • Sa galaxies show difference from universal rotation curve(Persic & Salucci 1991, 1996), rise rapidly in central regions, decline about ~10-20 percent from Vmax at intermediate radii, flatten out at large radii (Noordermeer et al. 2007). • High mass early type spiral galaxies lie on the TF relation only if asymptotic rotation velocity Vasymp Vmax (Noordermeer & Verheijen 2007) 8th Sino-German Workshop

  7. Rotation curve ofSa galaxies High mass disks 8th Sino-German Workshop

  8. Stellar population of spiral disks • Different morphological type spiral galaxies show systematical different colors • Earlier type spiral with redder colors • Bulge contamination effect, disks are similar (Deverux & Young 1991). • Different stellar population (star formation history) of the disks of different types (Kennicutt & Tamblyn 1994) • b=SFR/<SFR>past • Measurement of b: B-V color, EW(H) 8th Sino-German Workshop

  9. For SFR(t)=exp(-t/) b=0.33 = 5 Gy b=1  ~ infinity Kennicutt & Tamblyn 1994 8th Sino-German Workshop

  10. Type dependence of inverse TF relation (Theureau et al. 1997) • Diameter (inverse) Tully-Fisher relation • Vmax - Diameter (25 magarcsec-2) relation: logVmax=a’log D + b’ • Type dependent: early type galaxies have larger Vmax at given diameter • The surface brightness of spiral galaxies at D25 is mainly contributed by disks. • so it is unlikely that the Bulge + Disk composition could significantly contribute to any type dependence simply through the shift in D25 • The type dependence of inverse TF relation is caused by Vmax • Basic assumption: Vmaxappears at constant radius rmand rm is proportional to rd. (?) • Earlier type galaxies have larger bulge component, so that have larger Vmax at given D25 • log Vmax=0.5log(1+ Ld/Lb) =Yb/YdY - mass to light ratio • If =1, this model will not predict any type dependence of TF (Vm-Mag) relation 8th Sino-German Workshop

  11. our model: dynamics • Components: disk, bulge, dark matter, V(r)2=Vd2(r)+G(Mb+Mh)/r • Disk: exponential disk • Flattened disk geometry • Bulge: de Vaucouleurs profile • Dynamics: Hernquist model (1990) • Dark matter: initial NFW profile, adiabatic contraction when disk formation (Mo, Mao & White 1998) • Disk angular momentum • =0.05 • Bulge/disk ratio • Sb(0.3), Sc(0.1) • Baryon fraction  dark matter • 0.13/[1+(Mh/1012Msun)-2/3] • Size-mass relation (Shen et al. 2003) 8th Sino-German Workshop

  12. Model prediction: rotation curves • For the halo with the same Mass (Vc) and angular momentum (), the rotation curve of earlier type spiral galaxies rise more rapidly as observed • But the maximum rotation velocity, appears at ~3Rd, depends weakly on the bulge component • The morphological type of spiral galaxies may have intrinsic correlation with the initial angular momentum () of the host halos(?) 8th Sino-German Workshop

  13. Our model: stellar population • Stellar population model: (Bruzual & Charlot, 2007) • Bulge • Single stellar population, 10Gy • Disk • Star formation history: SFR(t) = exp(-t/) • Kennicutt & Tamblyn 1994 • Sb: = 5 Gy  b=0.3 • Sc: = 100 Gy  b=1, constant star formation • 10Gy old 8th Sino-German Workshop

  14. Model predicted TF relation of Sc galaxies • The slope of the TF relation is nicely reproduced • The zero-point of the TF relation suggests • the time scale of the disk star formation of Sc spirals >5Gy 8th Sino-German Workshop

  15. Model predicted morphological dependent TF relation • TheB/D composition effect only is not enough to explain the shift of the zero-point of the TF relation • The stellar population of later galaxies should be younger • The difference of the stellar population of the spiral disks(Sb/Sc) is not as large as that suggested by Kennicutt & Tamblyn 1994 • If so, the difference of the zero-point of TF relations is over-predicted 8th Sino-German Workshop

  16. conclusion • Understand the morphological dependent Tully-Fisher relation is very important when use it as a distance estimator. • The maximum rotation velocity shows weak dependence on the morphologies of spirals, at least for those later than Sb. • The stellar population of the later type spiral disks is averagely younger than earlier types. The morphological dependent TF relation provides a statistical constraint on this difference. 8th Sino-German Workshop

  17. Next……… • Test the disk instability model (Shen et al. 2003) • The bulge is formed through disk instability. The B/D ratio is determined by the properties of disks, e.g. the value of . later spirals are biased to those with large . • The current model assumes the same  for all types, implies that bulge formation is independent of disk properties (merge scenario?) • Difference between Sa/Sb • Need more observational constraints • What? 8th Sino-German Workshop

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