J/ApJ/868/55 Large-scale structure of M31 halo. II. PAndAS (McConnachie+, 2018)
The large-scale structure of the halo of the Andromeda galaxy.
II. Hierarchical structure in the Pan-Andromeda Archaeological Survey.
McConnachie A.W., Ibata R., Martin N., Ferguson A.M.N., Collins M., Gwyn S.,
Irwin M., Lewis G.F., Mackey A.D., Davidge T., Arias V., Conn A., Cote P.,
Crnojevic D., Huxor A., Penarrubia J., Spengler C., Tanvir N.,
Valls-Gabaud D., Babul A., Barmby P., Bate N.F., Bernard E., Chapman S.,
Dotter A., Harris W., McMonigal B., Navarro J., Puzia T.H., Rich R.M.,
Thomas G., Widrow L.M.
<Astrophys. J., 868, 55 (2018)>
=2018ApJ...868...55M 2018ApJ...868...55M
ADC_Keywords: Galaxies, photometry; Photometry, RI; Clusters, globular;
Magnitudes, absolute
Keywords: catalogs ; galaxies: general ; galaxies: structure ; Local Group
Abstract:
The Pan-Andromeda Archaeological Survey is a survey of >400deg2
centered on the Andromeda (M31) and Triangulum (M33) galaxies that has
provided the most extensive panorama of an L* galaxy group to large
projected galactocentric radii. Here, we collate and summarize the
current status of our knowledge of the substructures in the stellar
halo of M31, and discuss connections between these features. We
estimate that the 13 most distinctive substructures were produced by
at least 5 different accretion events, all in the last 3 or 4Gyr. We
suggest that a few of the substructures farthest from M31 may be
shells from a single accretion event. We calculate the luminosities of
some prominent substructures for which previous estimates were not
available, and we estimate the stellar mass budget of the outer halo
of M31. We revisit the problem of quantifying the properties of a
highly structured data set; specifically, we use the OPTICS clustering
algorithm to quantify the hierarchical structure of M31's stellar halo
and identify three new faint structures. M31's halo, in projection,
appears to be dominated by two "mega-structures", which can be
considered as the two most significant branches of a merger tree
produced by breaking M31's stellar halo into increasingly smaller
structures based on the stellar spatial clustering. We conclude that
OPTICS is a powerful algorithm that could be used in any astronomical
application involving the hierarchical clustering of points.
Description:
The primary observing goal of the Pan-Andromeda Archaeological Survey
(PAndAS) was to provide contiguous mapping of the resolved stellar
content of the halo of M31 out to approximately half of its halo
virial radius (in projection; Rvir∼300kpc), and it ran from 2008 to
2011.
In addition, the aim was to map M33 out to a broadly equivalent radius
(∼50kpc), accounting for the difference in mass between these galaxies.
PAndAS used the CFHT/MegaCam wide field camera in g- and i-band filters.
Table 2 contains the observing log (spanning 2008 August to 2011 February)
for the 2985 CFHT/MegaCam exposures.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 101 2985 Observing log for all of the 2985 CFHT/MegaCam
exposures contributing to the final PAndAS stacks
and catalogs
table3.dat 69 39 Probable and possible satellite galaxies of M31
table4.dat 73 112 *M31 globular clusters with Dproj>2°,
including globular clusters belonging to the
NGC 147, NGC 185, Andromeda I, and M33 systems
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Note on table4.dat: The outer halo globular clusters are taken from the
compilation of Mackey+ (2019MNRAS.484.1756M 2019MNRAS.484.1756M). In addition, we have
included the NGC 147/NGC 185 clusters from Veljanoski+ (2013MNRAS.435.3654V 2013MNRAS.435.3654V),
as well as the Andromeda I globular cluster described in
Caldwell+ (2017PASA...34...39C 2017PASA...34...39C). For completeness, we have also included the
six M33 outer halo globular clusters as listed in Table 3 of
Cockcroft+ (2011ApJ...730..112C 2011ApJ...730..112C).
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See also:
B/cfht : Log of CFHT Exposures (CADC, 1979-)
VII/86 : Groups of Galaxies. I. Nearby Groups (Huchra+ 1982)
J/A+AS/116/447 : M31 globulars clusters ellipticities (Staneva+, 1996)
J/MNRAS/390/1437 : Stellar streams in Andromeda (M31) (Chapman+, 2008)
J/ApJ/758/11 : Bayesian distances to M31 satellites (Conn+, 2012)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/768/172 : Kinematic analysis of red giant in M31 dSphs (Collins+, 2013)
J/ApJ/776/80 : PAndAS view of Andromeda satellites. I. (Martin+, 2013)
J/ApJ/779/7 : dSph satellites of M31. I. Variables in And XIX (Cusano+, 2013)
J/ApJ/790/73 : Iron abundance of RGBs in M31 satellites (Vargas+, 2014)
J/ApJ/803/63 : gr photometry of stars in Kim 2 (Kim+, 2015)
J/MNRAS/448/1314 : Line list for seven target PAndAS clusters (Sakari+, 2015)
J/ApJ/829/26 : Var. stars in the field of Andromeda XXV. III. (Cusano+, 2016)
J/ApJ/829/108 : Kinematic data of Galactic globular clusters (Eadie+, 2016)
J/ApJ/833/167 : PAndAS view of Andromeda satellites. II. (Martin+, 2016)
J/ApJ/836/137 : Deep, wide-field g,i imaging of And XXXI (Rhode+, 2017)
J/ApJ/837/54 : Variable stars in the globular cluster DDO 216-A1 (Cole+, 2017)
http://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/community/pandas/query.html :
PAndAS online catalog
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "Y/M/D" Obs.date UT date of observation start
12- 22 A11 "h:m:s" Obs.time [4/15] UT time of observation start
24- 36 F13.7 d MJD [52873.4/55597.3] Modified Julian Date
of observation start
38- 39 I2 h RAh [0/23] Hour of Right Ascension (J2000)
41- 42 I2 min RAm Minute of Right Ascension (J2000)
44- 48 F5.2 s RAs Second of Right Ascension (J2000)
50 A1 --- DE- [+] Sign of Declination (J2000)
51- 52 I2 deg DEd [27/50] Degree of Declination (J2000)
54- 55 I2 arcmin DEm Arcminute of Declination (J2000)
57- 60 F4.1 arcsec DEs Arcsecond of Declination (J2000)
62- 68 I7 --- ExpID [714745/1277842] Exposure identifier
70- 73 A4 --- FieldID Field identifier
75- 79 A5 --- Other Other identifier
81- 86 A6 --- PID Program identifier
88- 95 A8 --- Filter Filter used (g.MP9401, i.MP9701 or i.MP9702)
97-101 I5 s Exp [171/1160] Exposure time
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Prob Probable ("Pr") or
possible ("Po"; DM31<500kpc)
4- 19 A16 --- Gal Galaxy name
21 A1 --- n_Gal n: not in the PAndAS footprint
23- 24 I2 h RAh [0/23] Hour of right ascension (J2000)
26- 27 I2 min RAm Minute of right ascension (J2000)
29- 32 F4.1 s RAs Second of right ascension (J2000)
34 A1 --- DE- [+] Sign of declination (J2000)
35- 36 I2 deg DEd [14/59] Degree of declination (J2000)
38- 39 I2 arcmin DEm Arcminute of declination (J2000)
41- 42 I2 arcsec DEs Arcsecond of declination (J2000)
44- 47 I4 kpc DistMW [480/1216] Distance from MW (1)
49- 51 I3 kpc DistM31 [22/474] Distance from M31 (1)
53- 57 F5.1 mag VMag [-18.8/-5.9] Absolute V-band magnitude (1)
59- 61 F3.1 mag e_VMag [0.1/0.7] VMag uncertainty
63- 69 F7.2 10+6Msun Mass [0.02/3526] Stellar mass (G1)
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Note (1): Distances and magnitudes are from the updated compilation of
McConnachie (2012, J/AJ/144/4).
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Gal Galaxy name
18- 26 A9 --- GCl Globular cluster name
28- 29 I2 h RAh [0/23] Hour of right ascension (J2000)
31- 32 I2 min RAm Minute of right ascension (J2000)
34- 37 F4.1 s RAs Second of right ascension (J2000)
39 A1 --- DE- [+] Sign of declination (J2000)
40- 41 I2 deg DEd [28/49] Degree of declination (J2000)
43- 44 I2 arcmin DEm Arcminute of declination (J2000)
46- 47 I2 arcsec DEs Arcsecond of declination (J2000)
49- 54 F6.3 deg RM31 [2/17] Distance from M31 in degrees
56- 60 F5.1 kpc DM31 [28.7/231.2] Distance from M31 in kpc units
62- 66 F5.1 mag VMag [-10.8/-3.4]?=99.9 Absolute V-band magnitude
68- 73 F6.2 10+4Msun Mass [0.2/212.5]?=0 Stellar mass (G1)
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Global notes:
Note (G1): Stellar masses are calculated assuming a stellar mass-to-light ratio
of Υ*=1.2M☉/L_☉
(McGaugh & Schombert 2014AJ....148...77M 2014AJ....148...77M).
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History:
From electronic version of the journal
References:
Ibata et al. Paper I. 2014ApJ...780..128I 2014ApJ...780..128I
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Oct-2019