J/ApJ/734/L22 ACS Nearby Galaxy Survey Treasury (Williams+, 2011)
The history of star formation in galaxy disks in the local volume as measured by
the Advanced Camera for Surveys Nearby Galaxy Survey Treasury.
Williams B.F., Dalcanton J.J., Johnson L.C., Weisz D.R., Seth A.C.,
Dolphin A., Gilbert K.M., Skillman E., Rosema K., Gogarten S.M.,
Holtzman J., de Jong R.S.
<Astrophys. J., 734, L22 (2011)>
=2011ApJ...734L..22W 2011ApJ...734L..22W
ADC_Keywords: Galaxies, nearby ; Photometry, HST
Keywords: cosmology: observations - galaxies: evolution -
galaxies: stellar content
Abstract:
We present a measurement of the age distribution of stars residing in
spiral disks and dwarf galaxies. We derive a complete star formation
history of the ∼140Mpc3 covered by the volume-limited sample of
galaxies in the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey
Treasury (ANGST). The total star formation rate density history
(ρSFR(t)) is dominated by the large spirals in the volume,
although the sample consists mainly of dwarf galaxies. Our
ρSFR(t) shows a factor of ∼3 drop at z∼2, in approximate
agreement with results from other measurement techniques. While our
results show that the overall ρSFR(t) has decreased since z∼1,
the measured rates during this epoch are higher than those obtained
from other measurement techniques. This enhanced recent star formation
rate appears to be largely due to an increase in the fraction of star
formation contained in low-mass disks at recent times. Finally, our
results indicate that despite the differences at recent times, the
epoch of formation of ∼50% of the stellar mass in dwarf galaxies was
similar to that of ∼50% of the stellar mass in large spiral galaxies
(z≳2), despite the observed galaxy-to-galaxy diversity among the
dwarfs.
Description:
All of the data for this study were analyzed through the Advanced
Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST;
GO-10915) and ACS Nearby Galaxies: Reduce, Reuse, Recycle (ANGRRR;
AR-10945) programs. Our full sample is detailed in Table 1 and in
Dalcanton et al. (2009ApJS..183...67D 2009ApJS..183...67D).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 224 Data used for star formation history determination
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/AJ/127/2031 : Catalog of neighboring galaxies (Karachentsev+, 2004)
J/AJ/127/2002 : Star Formation Rate of NFGS galaxies (Kewley+, 2004)
http://www.nearbygalaxies.org/ : ANGST home page
http://archive.stsci.edu/prepds/angst/ : ANGST archive
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Galaxy Galaxy name
15- 19 I5 --- PID [5898/11986] Proposal ID. number of data used
21- 39 A19 --- Target Target name of dataset used
41- 45 A5 --- Cam Camera of dataset used; WFPC2 or ACS
47- 51 A5 --- Filt Broadband Filter (F435W, F475W, F555W, F606W or
F814W)
53- 57 I5 s tExp Total exposure time of data used
59- 64 I6 --- Nstars [325/442068] Number of stars in the photometry
catalog
66- 70 F5.2 mag m50 [24.46/29.69] Apparent magnitude of the 50%
completeness limit
72- 76 F5.2 mag M50 Absolute magnitude of the 50% completeness limit
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Nov-2012