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The morphological dependent Tully-Fisher relation of spiral galaxies

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Bulge contamination effect, disks are similar (Deverux & Young 1991) ... 8th Sino-German Workshop. 11. our model: dynamics ... Model predicted morphological ... – PowerPoint PPT presentation

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Title: The morphological dependent Tully-Fisher relation of spiral galaxies


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

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 .

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

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)?

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)

7
Rotation curve of Sa galaxies
High mass disks
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)
  • bSFR/ltSFRgtpast
  • Measurement of b B-V color, EW(H?)

9
For SFR(t)exp(-t/?) b0.33?? 5 Gy b1 ? ?
infinity
Kennicutt Tamblyn 1994
10
Type dependence of inverse TF relation (Theureau
et al. 1997)
  • Diameter (inverse) Tully-Fisher relation
  • Vmax - Diameter (25 magarcsec-2) relation
    logVmaxalog 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 Vmax appears at constant radius
    rm and rm is proportional to rd. (?)
  • Earlier type galaxies have larger bulge
    component, so that have larger Vmax at given D25
  • ? log Vmax0.5? log(1? Ld/Lb) ?Yb/Yd Y
    - mass to light ratio
  • If ?1, this model will not predict any type
    dependence of TF (Vm-Mag) relation

11
our model dynamics
  • Components disk, bulge, dark matter,
    V(r)2Vd2(r)G(MbMh)/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)

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(?)

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 ? b0.3
  • Sc ? 100 Gy ? b1, constant star formation
  • 10Gy old

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 ?gt5Gy

15
Model predicted morphological dependent TF
relation
  • The B/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

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.

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?
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