J/ApJ/827/L19 Central surface densities in SPARC disk galaxies (Lelli+, 2016)
The relation between stellar and dynamical surface densities in the central
regions of disk galaxies.
Lelli F., McGaugh S.S., Schombert J.M., Pawlowski M.S.
<Astrophys. J., 827, L19-L19 (2016)>
=2016ApJ...827L..19L 2016ApJ...827L..19L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, masses ; Morphology
Keywords: dark matter - galaxies: dwarf - galaxies: irregular -
galaxies: kinematics and dynamics - galaxies: spiral -
galaxies: structure
Abstract:
We use the Spitzer Photometry and Accurate Rotation Curves (SPARC)
database to study the relation between the central surface density of
stars Σ*(0) and dynamical mass Σdyn(0) in 135 disk
galaxies (S0 to dIrr). We find that Σdyn(0) correlates tightly
with Σ*(0) over 4dex. This central density relation can be
described by a double power law. High surface brightness galaxies are
consistent with a 1:1 relation, suggesting that they are
self-gravitating and baryon dominated in the inner parts. Low surface
brightness (LSB) galaxies systematically deviate from the 1:1 line,
indicating that the dark matter contribution progressively increases
but remains tightly coupled to the stellar one. The observed scatter
is small (∼0.2dex) and largely driven by observational uncertainties.
The residuals show no correlations with other galaxy properties like
stellar mass, size, or gas fraction.
Description:
We use galaxies from the Spitzer Photometry and Accurate Rotation
Curves (SPARC) database (Paper I; Lelli et al. 2016, Cat.
J/AJ/152/157). SPARC spans the widest possible range for disk
galaxies: morphologies from S0 to dIrr, luminosities from ∼107 to
∼1012L☉, effective surface brightnesses from ∼5 to
∼5000L☉/pc2, effective radii from ∼0.3 to ∼15kpc, rotation
velocities from ∼20 to ∼300km/s, and gas fractions from ∼0.01 to 0.95.
In Paper I, we describe the analysis of [3.6] images and the rotation
curve data. We also define a quality flag: Q=1 indicates galaxies with
high-quality HI data or hybrid HI/Hα rotation curves (99
objects), Q=2 indicates galaxies with minor asymmetries or HI data of
lower quality (64 objects), and Q=3 indicates galaxies with major
asymmetries, strong non-circular motions, or off-sets between stellar
and HI distributions (12 objects).
We exclude objects with Q=3 since the rotation curves do not
necessarily trace the equilibrium gravitational potential. We also
exclude face-on (i<30°) and edge-on (i>85°) galaxies due to
uncertain corrections on the rotation velocities and central surface
brightnesses, respectively. Our final sample consists of 135 galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
figure2.dat 50 135 Central dynamical surface density versus central
stellar surface density and total stellar mass
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See also:
J/AJ/152/157 : Mass models for 175 disk galaxies with SPARC (Lelli+, 2016)
J/A+A/566/A71 : HI study of 18 nearby dwarf galaxies (Lelli+, 2014)
J/MNRAS/433/L30 : Velocity gradient & brightness in disc galaxies (Lelli+ 2013)
Byte-by-byte Description of file: figure2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Galaxy name
13- 14 I2 --- T [0/11] Numerical Hubble Type (1)
16- 20 F5.2 [Msun/pc2] logSd [1.07/4.72] Dynamical surface density
Σdyn(0) (2)
22- 26 F5.2 [Msun/pc2] e_logSd [0.04/0.32] Mean error on logSd
28- 32 F5.2 [Msun/pc2] logS* [0.39/4.65] Stellar surface density
Σ*(0) (3)
34- 38 F5.2 [Msun/pc2] e_logS* [0.11/0.45] Mean error on logS*
40- 44 F5.2 [Msun] logM* [6.78/11.43] Log of the stellar mass (M*)
46- 50 F5.2 [Msun] e_logM* [0.11/0.29] Mean error on logM*
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Note (1): Galaxies are coded by numerical Hubble type defined as follows:
0 = S0;
1 = Sa;
2 = Sab;
3 = Sb;
4 = Sbc;
5 = Sc;
6 = Scd;
7 = Sd;
8 = Sdm;
9 = Sm;
10 = Im;
11 = BCD.
Note (2): Estimated at R=0 using Equation 16 of Toomre 1963ApJ...138..385T 1963ApJ...138..385T. See
Section 2.1 in the paper for additional details.
Note (3): Estimated at R=0 using Spitzer photometry at 3.6µm and assuming
M/L=0.5 and M/L=0.7 for disk and bulge components, respectively. Please
refer to Section 2.2 in the paper for more details.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 23-Feb-2017