2011ApJ...741...18B

Query : 2011ApJ...741...18B

2011ApJ...741...18B - Astrophys. J., 741, 18 (2011/November-1)

Where are the fossils of the first galaxies? II. True fossils, ghost halos, and the missing bright satellites.

BOVILL M.S. and RICOTTI M.

Abstract (from CDS):

We use a new set of cold dark matter simulations of the local universe to investigate the distribution of fossils of primordial dwarf galaxies within and around the Milky Way. Throughout, we build upon previous results showing agreement between the observed stellar properties of a subset of the ultra-faint dwarfs and our simulated fossils. Here, we show that fossils of the first galaxies have galactocentric distributions and cumulative luminosity functions consistent with observations. In our model, we predict ∼300 luminous satellites orbiting the Milky Way, 50%-70% of which are well-preserved fossils. Within the Milky Way virial radius, the majority of these fossils have luminosities LV< 106 L{x2609}. Despite our multidimensional agreement with observations at low masses and luminosities, the primordial model produces an overabundance of bright dwarf satellites (LV> 104 L{x2609}) with respect to observations where observations are nearly complete. The "bright satellite problem" is most evident in the outer parts of the Milky Way. We estimate that, although relatively bright, the primordial stellar populations are very diffuse, producing a population with surface brightnesses below surveys' detection limits, and are easily stripped by tidal forces. Although we cannot yet present unmistakable evidence for the existence of the fossils of first galaxies in the Local Group, the results of our studies suggest observational strategies that may demonstrate their existence: (1) the detection of "ghost halos" of primordial stars around isolated dwarfs would prove that stars formed in minihalos (M < 108 M{x2609}) before reionization and strongly suggest that at least a fraction of the ultra-faint dwarfs are fossils of the first galaxies; and (2) the existence of a yet unknown population of ∼150 Milky Way ultra-faints with half-light radii rhl~ 100-1000 pc and luminosities LV< 104 L{x2609}, detectable by future deep surveys. These undetected dwarfs would have the mass-to-light ratios, stellar velocity dispersions, and metallicities predicted in this work.

Abstract Copyright: ∼

Journal keyword(s): dark matter - galaxies: dwarf - galaxies: evolution - galaxies: formation - Local Group

Simbad objects: 71

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Number of rows : 71
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 MCG-03-01-015 G 00 01 57.9 -15 27 50   11.50 11.10 10.93   ~ 782 2
2 NAME Andromeda XVIII G 00 02 14.5 +45 05 20     16.0     ~ 129 0
3 NAME Andromeda XX G 00 07 30.70 +35 07 56.4     18.2     ~ 77 0
4 ESO 349-31 AG? 00 08 13.1536 -34 34 47.836   15.54   14.99   ~ 156 3
5 NGC 55 rG 00 14 53.602 -39 11 47.86 8.54 8.58 7.87 7.84   ~ 828 2
6 IC 10 rG 00 20 17.33520 +59 18 13.6480   13.6 9.5     ~ 1185 1
7 NAME Andromeda XXVI G 00 23 45.6 +47 54 58     17.3     ~ 76 0
8 NAME Cetus Dwarf Galaxy G 00 26 10.8 -11 03 14     13.2     ~ 257 0
9 NAME Andromeda XXV G 00 30 08.9 +46 51 07     14.8     ~ 120 0
10 NAME Andromeda III G 00 35 33.8 +36 29 52     14.4     ~ 309 0
11 NAME Andromeda XVII G 00 37 07.0 +44 19 20     15.8     ~ 101 0
12 NAME Andromeda XXVII G 00 37 27.1 +45 23 13     16.7     ~ 82 0
13 NGC 185 Sy2 00 38 57.9400026024 +48 20 15.035874648   9.10 9.2     ~ 840 1
14 M 110 GiG 00 40 22.0572349992 +41 41 07.507220136   8.92 8.07     ~ 1370 1
15 NAME Andromeda IV G 00 42 32.3 +40 34 19           ~ 80 0
16 M 32 GiG 00 42 41.82480 +40 51 54.6120 9.51 9.03 8.08     ~ 2236 2
17 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
18 NAME Andromeda I G 00 45 39.8 +38 02 28   13.9 12.7     ~ 355 0
19 NAME Andromeda XI G 00 46 20.0 +33 48 05     17.5     ~ 130 0
20 NAME Andromeda XII G 00 47 27.0 +34 22 29     18.3     ~ 124 0
21 NAME Andromeda XIII G 00 51 51.0 +33 00 16     18.1     ~ 128 0
22 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
23 NAME Pisces V G 00 59 29.8 +32 22 36     14.4     ~ 149 0
24 IC 1613 GiC 01 04 48.4071 +02 07 10.185   10.42 10.01 9.77   ~ 1316 2
25 NAME Andromeda V G 01 10 17.1 +47 37 41     15.3     ~ 215 0
26 NAME Andromeda XV G 01 14 18.7 +38 07 03     14.6     ~ 123 0
27 NAME Andromeda II G 01 16 29.8 +33 25 09     11.7     ~ 402 0
28 NAME Andromeda XXIV G 01 18 30.0 +46 21 58     16.3     ~ 64 0
29 NAME Andromeda XXII G 01 27 40.0 +28 05 25     18.0     ~ 95 0
30 NAME Andromeda XXIII G 01 29 21.8 +38 43 08     14.2     ~ 88 0
31 LGC-HII 3 GlC 01 32 45.9154376736 +30 41 35.328611508 17.829 19.085 18.479 18.586 18.719 ~ 10 0
32 NAME Phoenix Dwarf Galaxy Sy1 01 51 06.3 -44 26 41   13.48 13.2 12.69   ~ 575 2
33 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 299 0
34 MCG-06-07-001 G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1894 1
35 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
36 ESO 206-20A G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 1190 0
37 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
38 NAME Leo T G 09 34 53.4 +17 03 05     15.1     ~ 434 0
39 Z 153-10 G 09 59 26.46 +30 44 47.0 14.08 13.54 13.26 13.33   ~ 652 0
40 Z 36-12 H2G 10 00 00.8217342072 +05 20 09.533389560 12.77 12.25 11.89 11.71   ~ 569 0
41 NGC 3109 AG? 10 03 06.877 -26 09 34.46 11.10 10.42 10.04 9.91   ~ 825 2
42 NAME Antlia Dwarf Galaxy G 10 04 03.9 -27 20 01 16.73 15.69 15.17 15.00   ~ 221 1
43 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 517 1
44 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1284 1
45 MCG-01-26-030 H2G 10 11 00.5 -04 41 30 12.48 12.13 11.93 11.78   ~ 789 2
46 NAME Sextans dSph LSB 10 13 02.9 -01 36 53   12 10.4     ~ 921 0
47 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
48 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 345 0
49 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 899 0
50 NAME Leo V LSB 11 31 09.60 +02 13 12.0     16.0     ~ 234 0
51 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
52 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 482 1
53 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 287 2
54 Z 71-87 H2G 12 58 40.1930636208 +14 13 00.739589628 15.24 15.16 14.98 14.81   ~ 475 0
55 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 352 1
56 NAME Bootes II G 13 58 00.0 +12 51 00     15.4     ~ 269 0
57 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 491 0
58 Z 318-18 G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1459 0
59 ACO 2151 ClG 16 05 15.0 +17 44 55           ~ 594 3
60 LEDA 2801026 LSB 16 13 47.504 +54 22 08.25     15.9     ~ 115 0
61 Z 300-12 G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1428 1
62 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
63 NAME SDG G 18 55 19.0 -30 32 43   4.5 3.6     ~ 2438 2
64 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1661 0
65 MCG-02-53-003 G 20 46 51.7 -12 50 54 15.75 15.18 14.83 14.46   ~ 470 1
66 IC 5152 rG 22 02 41.521 -51 17 47.20   11.03 10.9 10.19   ~ 273 1
67 NAME Tuc Galaxy G 22 41 49.6 -64 25 10   15.7 15.2     ~ 324 0
68 NAME Pisces II G 22 58 31.0 +05 57 09     16.3     ~ 283 0
69 NAME Peg dSph GiG 23 51 46.3 +24 34 57   14.5 13.2     ~ 250 2
70 NAME Andromeda XXI G 23 54 47.7 +42 28 15     14.8     ~ 117 0
71 NAME Local Group GrG ~ ~           ~ 9325 0

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