J/ApJ/750/140 Candidate globular clusters in NGC 1316 (Goudfrooij, 2012)
Sizes, half-mass densities, and mass functions of star clusters in the merger
remnant NGC 1316: clues to the fate of second-generation globular clusters.
Goudfrooij P.
<Astrophys. J., 750, 140 (2012)>
=2012ApJ...750..140G 2012ApJ...750..140G
ADC_Keywords: Galaxies, optical ; Clusters, globular ; Photometry, HST
Keywords: galaxies: individual: NGC 1316 - galaxies: interactions -
galaxies: star clusters: general - globular clusters: general
Abstract:
We study mass functions of globular clusters derived from Hubble Space
Telescope/Advanced Camera for Surveys images of the early-type merger
remnant galaxy NGC 1316, which hosts a significant population of
metal-rich globular clusters of intermediate age (∼3Gyr). For the old,
metal-poor ("blue") clusters, the peak mass of the mass function Mp
increases with internal half-mass density ρh as
Mp∝ρh0.44, whereas it stays approximately constant
with galactocentric distance Rgal. The mass functions of these
clusters are consistent with a simple scenario in which they formed
with a Schechter initial mass function and evolved subsequently by
internal two-body relaxation. For the intermediate-age population of
metal-rich ("red") clusters, the faint end of the previously reported
power-law luminosity function of the clusters with Rgal>9kpc is due
to many of those clusters having radii larger than the theoretical
maximum value imposed by the tidal field of NGC 1316 at their Rgal.
This renders disruption by two-body relaxation ineffective. Only a few
such diffuse clusters are found in the inner regions of NGC 1316.
Completeness tests indicate that this is a physical effect. Using
comparisons with star clusters in other galaxies and cluster
disruption calculations using published models, we hypothesize that
most red clusters in the low-ρh tail of the initial distribution
have already been destroyed in the inner regions of NGC 1316 by tidal
shocking, and that several remaining low-ρh clusters will evolve
dynamically to become similar to "faint fuzzies" that exist in several
lenticular galaxies. Finally, we discuss the nature of diffuse red
clusters in early-type galaxies.
Description:
We use the HST/ACS imaging data set described previously in Goudfrooij
et al. (2004ApJ...613L.121G 2004ApJ...613L.121G). Briefly, this consists of several
wide-field channel (WFC) images taken with the F435W, F555W, and F814W
filters, on 2003 March 4 and 7, with total exposure times of 1860s,
6980s, and 4860s, respectively. The sample of star cluster candidates
in NGC 1316 and its subdivision in "old, metal-poor" ("blue") versus
"intermediate-age, metal-rich" ("red") clusters was adopted from
Goudfrooij et al. (2004ApJ...613L.121G 2004ApJ...613L.121G).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 478 Photometry, astrometry, and sizes of GC
candidates in NGC 1316
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See also:
J/A+A/552/A106 : NGC 1316 BVI images (Cantiello+, 2013)
J/A+A/543/A131 : NGC 1316 GC candidates photometry (Richtler+, 2012)
J/A+A/539/A11 : NGC 1316/1317 PN kinematics (McNeil-Moylan+, 2012)
J/ApJ/645/256 : XMM observations of Fornax A (NGC 1316) (Isobe+, 2006)
J/ApJ/586/826 : Chandra X-ray observations of NGC 1316 (Kim+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/478] Object identification number
<[G2012] NNN> in Simbad
5- 7 I3 --- GID ? Goudfrooij et al. 2001MNRAS.322..643G 2001MNRAS.322..643G
identifier; <[GMK2001] NNN> in Simbad
9- 18 F10.7 deg RAdeg Right Ascension (J2000) (1)
20- 30 F11.7 deg DEdeg Declination (J2000) (2)
32- 37 F6.3 mag Vmag [18.6/25.8] V-band VEGAMAG magnitude from F555W
39- 43 F5.3 mag e_Vmag [0.002/0.2] Error in Vmag
45- 49 F5.3 mag V-I [0.6/1.4] The (V-I) VEGAMAG color index
51- 55 F5.3 mag e_V-I Error in V-I
57- 61 F5.2 pc Rad [0.5/20] Measured half-light radius in pc (3)
63- 66 F4.2 pc e_Rad [0/7] Error in Rad
68- 70 I3 --- CK [15/100] King model concentration parameter
yielding the lowest χ2 (4)
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Note (1): RA of center of NGC 1316 in this system is 50.6739027
on the F555W ACS image.
Note (2): DEC of center of NGC 1316 in this system is -37.2079400
on the F555W ACS image.
Note (3): These are *measured* (not physical) values of the half-light radii.
Note (4): King (1962AJ.....67..471K 1962AJ.....67..471K) model concentration parameters
CK=rt/rc (where rt is the tidal radius and rc is the core
radius) of 15, 30, and 100. See section 3.1.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Dec-2013