J/ApJ/786/117 M31 PHAT star clusters ages and masses (Fouesneau+, 2014)
The panchromatic Hubble Andromeda treasury.
V. Ages and masses of the year 1 stellar clusters.
Fouesneau M., Johnson L.C., Weisz D.R., Dalcanton J.J., Bell E.F.,
Bianchi L., Caldwell N., Gouliermis D.A., Guhathakurta P., Kalirai J.,
Larsen S.S., Rix H.-W., Seth A.C., Skillman E.D., Williams B.F.
<Astrophys. J., 786, 117 (2014)>
=2014ApJ...786..117F 2014ApJ...786..117F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Extinction ; Stars, ages ;
Stars, masses
Keywords: galaxies: individual: M31 - galaxies: star clusters: general -
methods: data analysis - techniques: photometric
Abstract:
We present ages and masses for 601 star clusters in M31 from the
analysis of the six filter integrated light measurements from
near-ultraviolet to near-infrared wavelengths, made as part of the
Panchromatic Hubble Andromeda Treasury (PHAT). We derive the ages and
masses using a probabilistic technique, which accounts for the effects
of stochastic sampling of the stellar initial mass function. Tests on
synthetic data show that this method, in conjunction with the
exquisite sensitivity of the PHAT observations and their broad
wavelength baseline, provides robust age and mass recovery for
clusters ranging from ∼102 to 2x106 M☉. We find that the
cluster age distribution is consistent with being uniform over the
past 100 Myr, which suggests a weak effect of cluster disruption
within M31. The age distribution of older (>100 Myr) clusters falls
toward old ages, consistent with a power-law decline of index -1,
likely from a combination of fading and disruption of the clusters. We
find that the mass distribution of the whole sample can be well
described by a single power law with a spectral index of -1.9±0.1
over the range of 103-3x105 M☉. However, if we subdivide the
sample by galactocentric radius, we find that the age distributions
remain unchanged. However, the mass spectral index varies
significantly, showing best-fit values between -2.2 and -1.8, with the
shallower slope in the highest star formation intensity regions. We
explore the robustness of our study to potential systematics and conclude
that the cluster mass function may vary with respect to environment.
Description:
For this paper, we use the list of 601 high-probability cluster
candidates from the Johnson et al. (2012, J/ApJ/752/95) Year 1
catalog, which contains integrated photometry through six broadband
filters from the UV to the near-infrared: F275W (UV), F336W (U), F475W (g),
F814W (I), F110W (J), F160W (H). Clusters were detected by eye,
primarily based on the F475W images, and visually classified based on
their sizes, shapes, and concentrations as explained in Johnson et al.
(2012, J/ApJ/752/95).
Objects:
-----------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------
00 42 44.33 +41 16 07.5 M31 = NAME Andromeda
-----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 138 601 Ag-Mass and extinction results from
the analysis with discrete cluster models
--------------------------------------------------------------------------------
See also:
J/A+A/449/143 : Photometry of M31 globular cluster candidates (Ma+, 2006)
J/AJ/139/1438 : SED and age estimates of 104 M31 globular clusters
(Wang+, 2010)
J/ApJ/752/95 : PHAT stellar cluster survey. I. Year 1 (Johnson+, 2012)
J/A+A/549/A60 : Ages and [Fe/H] of M31 globular clusters (Cezario+, 2013)
J/ApJ/762/123 : PHAT. IV. Initial Mass Function (Weisz+, 2013)
J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014)
J/ApJ/827/33 : PHAT. XVI. Star cluster masses and ages (Johnson+, 2016)
J/A+A/602/A112 : M31 PHAT star clusters (de Meulenaer+, 2017)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- PCID [1/1728] PHAT identifier ([JSD2012] PC NNNN
in Simbad) (1)
6- 23 F18.15 deg RAdeg Right Ascension in decimal degrees (J2000)
25- 42 F18.15 deg DEdeg Declination in decimal degrees (J2000)
44- 46 F3.1 mag AV-best ? Best V band extinction (2)
49- 51 F3.1 mag AV-p16 ? The 16th percentile V band extinction
54- 56 F3.1 mag AV-p84 ? The 84th percentile V band extinction
59- 61 F3.1 mag AV-p2.5 ? The 2.5th percentile V band extinction
64- 66 F3.1 mag AV-p97.5 ? The 97.5th percentile V band extinction
68- 73 F6.3 [yr] logA-best ? Best log age (2)
75- 80 F6.3 [yr] logA-p16 ? The 16th percentile log age
82- 87 F6.3 [yr] logA-p84 ? The 84th percentile log age
89- 94 F6.3 [yr] logA-p2.5 ? The 2.5th percentile log age
96-101 F6.3 [yr] logA-p97.5 ? The 97.5th percentile log age
104-108 F5.3 [Msun] logM-bset ? Best log mass (2)
111-115 F5.3 [Msun] logM-p16 ? The 16th percentile mass
118-122 F5.3 [Msun] logM-p84 ? The 84th percentile mass
125-129 F5.3 [Msun] logM-p2.5 ? The 2.5th percentile mass
132-136 F5.3 [Msun] logM-p97.5 ? The 97.5th percentile mass
138 I1 --- CFlag [0/1]? Suspicious fit from visual
color-magnitude inspection (3)
--------------------------------------------------------------------------------
Note (1): As in Johnson et al. (2012, J/ApJ/752/95).
Note (2): Represents the triplet which maximize the full posterior.
Note (3): Flag as follows:
0 = no;
1 = yes.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Dalcanton et al. PHAT Suvey 2012ApJS..200...18D 2012ApJS..200...18D
Rosenfield et al. Paper I 2012ApJ...755..131R 2012ApJ...755..131R
Williams et al. Paper II 2012ApJ...759...46W 2012ApJ...759...46W
Beerman et al. Paper III 2012ApJ...760..104B 2012ApJ...760..104B
Weisz et al. Paper IV 2013ApJ...762..123W 2013ApJ...762..123W Cat. J/ApJ/762/123
Fouesneau et al. Paper V 2014ApJ...786..117F 2014ApJ...786..117F
Simones et al. Paper VI 2014ApJ...788...12S 2014ApJ...788...12S
Dong et al. Paper VII 2014ApJ...785..136D 2014ApJ...785..136D
Dalcanton et al. Paper VIII 2015ApJ...814....3D 2015ApJ...814....3D
Veyette et al. Paper IX 2014ApJ...792..121V 2014ApJ...792..121V
Williams et al. Paper X 2014ApJS..215....9W 2014ApJS..215....9W Cat. J/ApJS/215/9
Lewis et al. Paper XI 2015ApJ...805..183L 2015ApJ...805..183L
Gregersen et al. Paper XII 2015AJ....150..189G 2015AJ....150..189G
Wagner-Kaiser et al. Paper XIII 2015MNRAS.451..724W 2015MNRAS.451..724W Cat. J/MNRAS/451/724
Senchyna et al. Paper XIV 2015ApJ...813...31S 2015ApJ...813...31S
Gordon et al. Paper XV 2016ApJ...826..104G 2016ApJ...826..104G
Johnson et al. Paper XVI 2016ApJ...827...33J 2016ApJ...827...33J Cat. J/ApJ/827/33
Lewis et al. Paper XVII 2017ApJ...834...70L 2017ApJ...834...70L
Johnson et al. Paper XVIII 2017ApJ...839...78J 2017ApJ...839...78J
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 21-Jul-2017