J/ApJ/799/159 Globular cluster populations in S4G galaxies (Zaritsky+, 2015)
Globular cluster populations: first results from S4G early-type galaxies.
Zaritsky D., Aravena M., Athanassoula E., Bosma A., Comeron S.,
Elmegreen B.G., Erroz-Ferrer S., Gadotti D.A., Hinz J.L., Ho L.C.,
Holwerda B., Knapen J.H., Laine J., Laurikainen E., Munoz-Mateos J.C.,
Salo H., Sheth K.
<Astrophys. J., 799, 159 (2015)>
=2015ApJ...799..159Z 2015ApJ...799..159Z
ADC_Keywords: Galaxies, IR ; Clusters, globular
Keywords: galaxies: evolution; galaxies: formation;
galaxies: star clusters: general; galaxies: stellar content
Abstract:
Using 3.6µm images of 97 early-type galaxies, we develop and
verify methodology to measure globular cluster populations from the
S4G survey images. We find that (1) the ratio, TN, of the number
of clusters, NCL, to parent galaxy stellar mass, M*, rises weakly
with M* for early-type galaxies with M*>1010M☉ when we
calculate galaxy masses using a universal stellar initial mass
function (IMF) but that the dependence of TN on M* is removed
entirely once we correct for the recently uncovered systematic
variation of IMF with M*; and (2) for M*<1010M☉, there is
no trend between NCL and M*, the scatter in TNis significantly
larger (approaching two orders of magnitude), and there is evidence to
support a previous, independent suggestion of two families of
galaxies. The behavior of NCL in the lower-mass systems is more
difficult to measure because these systems are inherently
cluster-poor, but our results may add to previous evidence that large
variations in cluster formation and destruction efficiencies are to be
found among low-mass galaxies. The average fraction of stellar mass in
clusters is ∼0.0014 for M*>1010M☉ and can be as large as
∼0.02 for less massive galaxies. These are the first results from the
S4G sample of galaxies and will be enhanced by the sample of
early-type galaxies now being added to S4G and complemented by the
study of later-type galaxies within S4G.
Description:
The parent sample for this study is the S4G sample, which currently
consists of 2352 galaxies selected as described by Sheth et al.
(2010, J/PASP/122/1397). We observed these galaxies using the Spitzer
Space Telescope and its Infrared Array Camera.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 82 97 Globular cluster population properties
--------------------------------------------------------------------------------
See also:
J/ApJS/217/32 : S4G galaxy morphologies in the CVRHS system (Buta+, 2015)
J/MNRAS/444/3015 : Morphologies of S4G galaxies (Laine+, 2014)
J/MNRAS/441/1992 : Galaxies with disc breaks in S4G and NIRS0S (Laine+, 2014)
J/A+A/569/A91 : Optical imaging for S4G (Knapen+, 2014)
J/AJ/147/134 : Tully-Fisher relation for S4G galaxies (Zaritsky+, 2014)
J/ApJ/772/135 : 3.6um surface brightness from S4G (Zaritsky+, 2013)
J/ApJ/772/82 : A catalog of globular cluster systems (Harris+, 2013)
J/MNRAS/428/389 : SLUGGS globular clusters in early-type gal. (Pota+, 2013)
J/AJ/143/87 : Massive M31 globular clusters with IRAC (Barmby+, 2012)
J/ApJS/197/33 : The M87 globular cluster system (Strader+, 2011)
J/PASP/122/1397 : Spitzer Survey of Stellar Structure in Gal. (Sheth+, 2010)
J/AJ/139/1871 : Kinematics of globulars in NGC 5128 (Woodley+, 2010)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/MNRAS/389/1150 : Spitzer photom. of globulars in 2 galaxies (Spitler+, 2008)
J/ApJ/681/197 : ACS Virgo Cluster Survey. XV (Peng+, 2008)
J/MNRAS/385/361 : BVRcIc phot. of NGC 821 globular clusters (Spitler+, 2008)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/A+A/433/43 : C-T1 phot. of NGC 4636 globular clusters (Dirsch+, 2005)
J/AJ/105/1762 : Globular clusters around NGC 1399 (Ostrov+ 1993)
http://irsa.ipac.caltech.edu/data/SPITZER/S4G/ : S4G home page on NASA/IRSA
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Galaxy name
12- 16 F5.2 mag DM [30.2/32.4] Galaxy distance modulus
18- 19 I2 --- TT [-5/1] Galaxy T-Type of Buta et al. 2015
(J/ApJS/217/32)
21- 26 F6.1 mag [3.6] [7.9/15.2]?=-999 Spitzer/IRAC 3.6 micron
AB magnitude (1)
28- 33 F6.1 mag [4.5] [8.4/15.7]?=-999 Spitzer/IRAC 4.5 microns
AB magnitude (1)
35- 38 I4 --- N50 [2/2698] Number of clusters within 50kpc (2)
40- 46 F7.2 GMsun-1 TN [0.05/142]?=-999.99 Specific frequency TN of
globular clusters per 109M☉ (3)
48- 54 F7.2 GMsun-1 e_TN ?=-999.99 Lower uncertainty on TN (3)
56- 62 F7.2 GMsun-1 E_TN ?=-999.99 Upper uncertainty on TN (3)
64- 68 F5.2 [pc-2] Back Logarithm of background level (4)
70- 74 F5.2 --- a Cluster radial profile fitting parameter (5)
76- 80 F5.2 --- b Cluster radial profile fitting parameter (5)
82- 82 I1 --- Q [0/1] Quality flag; 1=good, 0=poor
--------------------------------------------------------------------------------
Note (1): Of the galaxies as measured by Munoz-Mateos et al.
(2015arXiv150503534M 2015arXiv150503534M). -999.0 if unavailable from S4G.
Note (2): Derived from model fit of fixed power-law slope within 50 kpc
of the galaxy. Intended to represent total number of clusters.
Note (3): Specific frequency relative to the galaxy's stellar mass (TN),
corresponding to N50 in units of number per 109M_☉ (as
introduced by Zepf & Ashman 1993MNRAS.264..611Z 1993MNRAS.264..611Z). See section 2.2.
Note (4): Clusters per projected area.
Note (5): projected density = a*rb.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Zaritsky et al. Paper II. 2016ApJ...818...99Z 2016ApJ...818...99Z Cat. J/ApJ/818/99
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Jun-2015