J/ApJ/766/109 Color/age/metallicity gradients of E galaxies (Kim+, 2013)
Optical-near-infrared color gradients and merging history of elliptical
galaxies.
Kim D., Im M.
<Astrophys. J., 766, 109 (2013)>
=2013ApJ...766..109K 2013ApJ...766..109K
ADC_Keywords: Galaxies, optical ; Photometry, infrared ; Photometry, SDSS ;
Redshifts
Keywords: galaxies: elliptical and lenticular, cD; galaxies: evolution;
galaxies: interactions; galaxies: peculiar
Abstract:
In order to understand the past merging history of elliptical
galaxies, we studied the optical-near-infrared (NIR) color gradients
of 204 elliptical galaxies. These galaxies are selected from the
overlap region of the Sloan Digital Sky Survey (SDSS) Stripe 82 and
the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS).
The use of optical and NIR data (g, r, and K) provides large
wavelength baselines, and breaks the age-metallicity degeneracy,
allowing us to derive age and metallicity gradients. The use of the
deep SDSS Stripe 82 images makes it possible for us to examine how the
color/age/metallicity gradients are related to merging features. We
find that the optical-NIR color and the age/metallicity gradients of
elliptical galaxies with tidal features are consistent with those of
relaxed ellipticals, suggesting that the two populations underwent a
similar merging history on average and that mixing of stars was more
or less completed before the tidal features disappeared. Elliptical
galaxies with dust features have steeper color gradients than the
other two types, even after masking out dust features during the
analysis, which can be due to a process involving wet merging. More
importantly, we find that the scatter in the color/age/metallicity
gradients of the relaxed and merging feature types decreases as their
luminosities (or masses) increase at M>1011.4M☉ but stays
large at lower luminosities. Mean metallicity gradients appear nearly
constant over the explored mass range, but a possible flattening is
observed at the massive end.
Description:
The elliptical galaxies that we study in this paper are selected from
a catalog of nearby (z<0.05), luminous (Mr←20.5) early-type
galaxies in the Sloan Digital Sky Survey (SDSS) Stripe 82 imaging area
which is located along the celestial equator in the Southern Galactic
Cap (-50°<RA<59°, -1.25°<DEC<1.25°; Kaviraj
2010, J/MNRAS/406/382).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 108 205 List of ellipticals and their properties
--------------------------------------------------------------------------------
See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/ApJS/210/22 : Herschel Stripe 82 survey (HerS) first catalog (Viero+, 2014)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/ApJ/727/14 : Merging galaxy cluster A2255 in mid-IR (Shim+, 2011)
J/other/RAA/11.309 : Nearby early-type galaxies in Stripe 82 (Jiang+, 2011)
J/MNRAS/406/382 : Early-type galaxies in the SDSS Stripe82 (Kaviraj, 2010)
J/A+A/463/455 : Nearby early-type gal. with ionized gas. III. (Annibali+, 2007)
J/ApJ/650/148 : GOODS blue early-type galaxies (Lee+, 2006)
J/AJ/130/2647 : Tidal features of 126 nearby red galaxies (van Dokkum+, 2005)
J/ApJ/571/136 : DEEP Groth Strip survey. X. (Im+, 2002)
J/AJ/100/1091 : UBR photometry of 39 elliptical galaxies (Peletier+ 1990)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [24/3726] Kaviraj, 2010, J/MNRAS/406/382
catalog identifier
6- 11 F6.4 --- z [0.01/0.05] redshift
13- 17 F5.2 arcsec reffr [1.6/27] The r band effective radius
19- 23 F5.2 arcsec reffK [1.6/18] The K band effective radius
25- 29 F5.2 --- g(g-r) The (g-r) color gradient (1)
31- 34 F4.2 --- e_g(g-r) Uncertainty in g(g-r)
36- 40 F5.2 --- g(r-K) [-1.8/1.1] The (r-K) color gradient (1)
42- 45 F4.2 --- e_g(r-K) Uncertainty in g(r-K)
47- 51 F5.2 --- g(g-K) The (g-K) color gradient (1)
53- 56 F4.2 --- e_g(g-K) Uncertainty in g(g-K)
58- 62 F5.2 --- g(t) [-1.4/4.8] The age gradient (2)
64- 67 F4.2 --- e_g(t) [0/3.3] Uncertainty in g(t)
69- 73 F5.2 --- g(Z) [-2.7/1.7] The metallicity gradient (2)
75- 78 F4.2 --- e_g(Z) Uncertainty in g(Z)
80- 85 F6.2 mag KMag [-24.4/-21.3] Absolute K band AB magnitude
87- 90 F4.2 mag e_KMag [0/0.05] Uncertainty in KMag
92- 96 F5.2 [Msun] logM* [10.6/11.9] Log stellar mass from KMag
98-101 F4.2 [Msun] e_logM* [0/0.02] Uncertainty in logM*
103-106 F4.2 --- B/T [0.5/1] Bulge to total light ratio
108 A1 --- Type [RTD] Morpological type: R=relaxed,
T=tidal-feature, D=dust-feature.
--------------------------------------------------------------------------------
Note (1): the gradient of color (a-b) g(a-b)=∇(a-b) is:
∇(a-b) = Δ(SB(a)-SB(b))/Δlog(r/reff(b))
Note (2): grandients defined by:
∇(t) = Δlog(t)/Δlog(r/reff(K))
∇(Z) = Δlog(Z)/Δlog(r/reff(K))
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 12-Nov-2014