2011ApJ...732...76R

Query : 2011ApJ...732...76R

2011ApJ...732...76R - Astrophys. J., 732, 76 (2011/May-2)

PAndAS' progeny: extending the M31 dwarf galaxy cabal.

RICHARDSON J.C., IRWIN M.J., McCONNACHIE A.W., MARTIN N.F., DOTTER A.L., FERGUSON A.M.N., IBATA R.A., CHAPMAN S.C., LEWIS G.F., TANVIR N.R. and RICH R.M.

Abstract (from CDS):

We present the discovery of five new dwarf galaxies, Andromeda XXIII-XXVII, located in the outer halo of M31. These galaxies were discovered during the second year of data from the Pan-Andromeda Archaeological Survey (PAndAS), a photometric survey of the M31/M33 subgroup conducted with the MegaPrime/MegaCam wide-field camera on the Canada-France-Hawaii Telescope. The current PAndAS survey now provides an almost complete panoramic view of the M31 halo out to an average projected radius of ∼150 kpc. Here we present for the first time the metal-poor stellar density map for this whole region, not only as an illustration of the discovery space for satellite galaxies, but also as a birds-eye view of the ongoing assembly process of an L* disk galaxy. Four of the newly discovered satellites appear as well-defined spatial overdensities of stars lying on the expected locus of metal-poor (-2.5 < [Fe/H] < -1.3) red giant branch stars at the distance of M31. The fifth overdensity, And XXVII, is embedded in an extensive stream of such stars and is possibly the remnant of a strong tidal disruption event. Based on distance estimates from horizontal branch magnitudes, all five have metallicities typical of dwarf spheroidal galaxies ranging from [Fe/H] =-1.7±0.2 to [Fe/H] =-1.9±0.2 and absolute magnitudes ranging from MV= -7.1±0.5 to MV= -10.2 ± 0.5. These five additional satellites bring the number of dwarf spheroidal galaxies in this region to 25 and continue the trend whereby the brighter dwarf spheroidal satellites of M31 generally have much larger half-light radii than their Milky Way counterparts. With an extended sample of M31 satellite galaxies, we also revisit the spatial distribution of this population and in particular we find that, within the current projected limits of the PAndAS survey, the surface density of satellites is essentially constant out to 150 kpc. This corresponds to a radial density distribution of satellites varying as r–1, a result seemingly in conflict with the predictions of cosmological simulations.

Abstract Copyright: ∼

Journal keyword(s): galaxies: dwarf - galaxies: structure - Local Group

Nomenclature: And R (Nos XXIII-XXVII) added = NAME Andromeda R (Nos XXIII-XXVII) added.

Simbad objects: 37

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Number of rows : 37
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Andromeda XVIII G 00 02 14.5 +45 05 20     16.0     ~ 129 0
2 NAME Andromeda XX G 00 07 30.70 +35 07 56.4     18.2     ~ 77 0
3 And XIX G 00 19 32.10 +35 02 37.1     15.6     ~ 168 0
4 NAME Andromeda XXVI G 00 23 45.6 +47 54 58     17.3     ~ 76 0
5 NAME Andromeda XXV G 00 30 08.9 +46 51 07     14.8     ~ 120 0
6 NGC 147 GiG 00 33 12.120 +48 30 31.46   12.0 9.5     ~ 720 1
7 NAME Andromeda III G 00 35 33.8 +36 29 52     14.4     ~ 309 0
8 NAME Andromeda XVII G 00 37 07.0 +44 19 20     15.8     ~ 101 0
9 NAME Andromeda XXVII G 00 37 27.1 +45 23 13     16.7     ~ 82 0
10 NGC 185 Sy2 00 38 57.9400026024 +48 20 15.035874648   9.10 9.2     ~ 840 1
11 M 110 GiG 00 40 22.0572349992 +41 41 07.507220136   8.92 8.07     ~ 1370 1
12 M 32 GiG 00 42 41.82480 +40 51 54.6120 9.51 9.03 8.08     ~ 2236 2
13 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
14 NAME Andromeda I G 00 45 39.8 +38 02 28   13.9 12.7     ~ 355 0
15 NAME Andromeda XI G 00 46 20.0 +33 48 05     17.5     ~ 130 0
16 NAME Andromeda XII G 00 47 27.0 +34 22 29     18.3     ~ 124 0
17 NAME Andromeda XIV G 00 51 35.0 +29 41 49     15.9     ~ 132 0
18 NAME Andromeda XIII G 00 51 51.0 +33 00 16     18.1     ~ 128 0
19 NAME Andromeda IX G 00 52 53.0 +43 11 45     16.3     ~ 176 1
20 NAME Pisces V G 00 59 29.8 +32 22 36     14.4     ~ 149 0
21 NAME Andromeda X G 01 06 33.70 +44 48 15.8     16.6     ~ 125 1
22 NAME Andromeda XV G 01 14 18.7 +38 07 03     14.6     ~ 123 0
23 NAME Andromeda II G 01 16 29.8 +33 25 09     11.7     ~ 402 0
24 NAME Andromeda XXIV G 01 18 30.0 +46 21 58     16.3     ~ 64 0
25 NAME Andromeda XXII G 01 27 40.0 +28 05 25     18.0     ~ 95 0
26 NAME Andromeda XXIII G 01 29 21.8 +38 43 08     14.2     ~ 88 0
27 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 6226 1
28 NAME Leo T G 09 34 53.4 +17 03 05     15.1     ~ 434 0
29 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1284 1
30 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
31 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 899 0
32 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
33 ACO 2151 ClG 16 05 15.0 +17 44 55           ~ 594 3
34 NAME Andromeda VII GiG 23 26 31.0 +50 40 33   13.6 11.8     ~ 222 1
35 NAME Peg dSph GiG 23 51 46.3 +24 34 57   14.5 13.2     ~ 250 2
36 NAME Andromeda XXI G 23 54 47.7 +42 28 15     14.8     ~ 117 0
37 NAME Local Group GrG ~ ~           ~ 9325 0

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