C.D.S. - SIMBAD4 rel 1.7 - 2019.11.18CET08:36:14

2018MNRAS.473.5514T - Mon. Not. R. Astron. Soc., 473, 5514-5531 (2018)

The Smith Cloud: surviving a high-speed transit of the Galactic disc.


Abstract (from CDS):

The origin and survival of the Smith high-velocity H I cloud has so far defied explanation. This object has several remarkable properties: (i) its prograde orbit is ≃100 km s–1 faster than the underlying Galactic rotation; (ii) its total gas mass (>= 4 x 106 M) exceeds the mass of all other high-velocity clouds (HVCs) outside of the Magellanic Stream; (iii) its head-tail morphology extends to the Galactic H I disc, indicating some sort of interaction. The Smith Cloud's kinetic energy rules out models based on ejection from the disc. We construct a dynamically self-consistent, multi-phase model of the Galaxy with a view to exploring whether the Smith Cloud can be understood in terms of an infalling, compact HVC that has transited the Galactic disc. We show that while a dark-matter (DM) free HVC of sufficient mass and density can reach the disc, it does not survive the transit. The most important ingredient to survival during a transit is a confining DM subhalo around the cloud; radiative gas cooling and high spatial resolution (<= 10pc) are also essential. In our model, the cloud develops a head-tail morphology within ∼10 Myr before and after its first disc crossing; after the event, the tail is left behind and accretes on to the disc within ∼400 Myr. In our interpretation, the Smith Cloud corresponds to a gas 'streamer' that detaches, falls back and fades after the DM subhalo, distorted by the disc passage, has moved on. We conclude that subhaloes with MDM <= 109 M have accreted ∼109 M of gas into the Galaxy over cosmic time - a small fraction of the total baryon budget.

Abstract Copyright:

Journal keyword(s): methods: numerical - ISM: clouds - ISM: general - ISM: individual objects: Smith Cloud - Galaxy: halo - intergalactic medium

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 NAME Magellanic Stream HVC 00 32 -30.0           ~ 776 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9107 1
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14346 1
4 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11047 0
5 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1650 2
6 NAME Gal Center Positive HVC 20 51.2 +01 41           ~ 70 1

    Equat.    Gal    SGal    Ecl

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