2023MNRAS.520.1704B

Query : 2023MNRAS.520.1704B

2023MNRAS.520.1704B - Mon. Not. R. Astron. Soc., 520, 1704-1720 (2023/April-1)

Determining satellite infall times using machine learning.

BARMENTLOO S. and CAUTUN M.

Abstract (from CDS):

A key unknown of the Milky Way (MW) satellites is their orbital history, and, in particular, the time they were accreted onto the MW system since it marks the point where they experience a multitude of environmental processes. We present a new methodology for determining infall times, namely using a neural network (NN) algorithm. The NN is trained on MW-analogues in the EAGLE hydrodynamical simulation to predict if a dwarf galaxy is at first infall or a backsplash galaxy and to infer its infall time. The resulting NN predicts with 85-per cent accuracy if a galaxy currently outside the virial radius is a backsplash satellite and determines the infall times with a typical 68-per cent confidence interval of 4.4 Gyr. Applying the NN to MW dwarfs with Gaia EDR3 proper motions, we find that all of the dwarfs within 300 kpc had been inside the Galactic halo. The overall MW satellite accretion rate agrees well with the theoretical prediction except for late times when the MW shows a second peak at a lookback time of 1.5 Gyr corresponding to the infall of the LMC and its satellites. We also find that the quenching times for ultrafaint dwarfs show no significant correlation with infall time and thus supporting the hypothesis that they were quenched during reionization. In contrast, dwarfs with stellar masses above 105 M⊙ are found to be consistent with environmental quenching inside the Galactic halo, with star-formation ceasing on average at $0.5^{+0.9}_{-1.2}$ Gyr after infall.

Abstract Copyright: © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society

Journal keyword(s): Galaxy: formation - Galaxy: halo - galaxies: dwarf - galaxies: interactions - cosmology: theory

Simbad objects: 49

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Number of rows : 49
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 Tuc IV G 00 02.9 -60 51           ~ 90 0
2 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
4 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1498 4
5 NAME Tri II G 02 13 17.40 +36 10 42.4           ~ 164 0
6 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 299 0
7 NAME Hydrus I G 02 29 33.4 -79 18 32           ~ 80 0
8 MCG-06-07-001 G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1894 1
9 NAME Hor I G 02 55 31.7 -54 07 08           ~ 169 0
10 NAME Horologium II G 03 16 32.1 -50 01 05           ~ 76 0
11 NAME Reticulum II G 03 35 42.1 -54 02 57           ~ 375 0
12 NAME Reticulum III G 03 45.4 -60 27           ~ 67 0
13 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
14 NAME Col I G 05 31.4 -28 02           ~ 60 0
15 ESO 206-20A G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 1190 0
16 NAME Carina II Dwarf Galaxy G 07 36 25.6 -57 59 57           ~ 86 0
17 NAME Car III Dwarf Galaxy G 07 38 31.2 -57 53 59           ~ 81 0
18 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
19 NAME Antlia II Dwarf Galaxy G 09 35 32.8 -36 46 02           ~ 109 0
20 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 517 1
21 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1284 1
22 NAME Sextans dSph LSB 10 13 02.9 -01 36 53   12 10.4     ~ 921 0
23 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
24 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 345 0
25 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 899 0
26 NAME Leo V LSB 11 31 09.60 +02 13 12.0     16.0     ~ 234 0
27 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
28 NAME Crater II Dwarf Galaxy G 11 49 14 -18 24.8           ~ 176 0
29 NAME Hydra II G 12 21 42.1 -31 59 07           ~ 118 0
30 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 482 1
31 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 287 2
32 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 352 1
33 NAME Bootes II G 13 58 00.0 +12 51 00     15.4     ~ 269 0
34 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 491 0
35 Z 318-18 G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1459 0
36 NAME Draco II Gl? 15 52 47.6 +64 33 55           ~ 138 0
37 NAME Hercules Dwarf Galaxy G 16 31 02.0 +12 47 30     14.0     ~ 379 1
38 Z 300-12 G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1428 1
39 NAME SDG G 18 55 19.0 -30 32 43   4.5 3.6     ~ 2438 2
40 NAME Sagittarius II Gl? 19 52 40.5 -22 04 05           ~ 97 0
41 NAME Gru II G 22 04.1 -46 26           ~ 110 0
42 NAME Aquarius 2 G 22 33 55.5 -09 19 39           ~ 66 0
43 NAME Tuc II G 22 51 55.1 -58 34 08           ~ 192 0
44 NAME Grus I G 22 56 42.4 -50 09 48           ~ 126 0
45 NAME Pisces II G 22 58 31.0 +05 57 09     16.3     ~ 283 0
46 NAME Tuc V G 23 37.4 -63 16           ~ 84 0
47 NAME Phe II G 23 39 59.4 -54 24 22           ~ 107 0
48 NAME Tuc III G 23 56.6 -59 36           ~ 229 0
49 NAME Gaia Enceladus-Sausage St* ~ ~           ~ 860 0

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