The effect of stellar feedback on a Milky Way-like galaxy and its gaseous halo

Context. The faintest Local Group galaxies found lurking in and around the Milky Way halo provide a unique test bed for theories of structure formation and evolution on small scales. Deep Subaru and Hubble Space Telescope photometry demonstrates that the stellar populations of these galaxies are old and that the star formation activity did not last longer than 2 Gyr in these systems. A few mechanisms that may lead to such a rapid quenching have been investigated by means of hydrodynamic simulations, but these have not provided any final assessment so far. Aims. This is the first in a series of papers aimed at analyzing the roles of stellar feedback, ram pressure stripping, host-satellite tidal interactions, and reionization in cleaning the lowest mass Milky Way companions of their cold gas using high-resolution, three-dimensional hydrodynamic simulations. Methods. We simulated an isolated ultrafaint dwarf galaxy loosely modeled after Boötes I, and examined whether or not stellar feedback alone could drive a substantial fraction of the ambient gas out from the shallow potential well. Results. In contrast to simple analytical estimates, but in agreement with previous hydrodynamical studies, we find that most of the cold gas reservoir is retained. Conversely, a significant amount of the metal-enriched stellar ejecta crosses the boundaries of the computational box with velocities exceeding the local escape velocity and is, thus, likely lost from the system. Conclusions. Although the total energy output from multiple supernova explosions exceeds the binding energy of the gas, no galactic-scale outflow develops in our simulations and as such, most of the ambient medium remains trapped within the weak potential well of the model galaxy. It seems thus unavoidable that to explain the dearth of gas in ultrafaint dwarf galaxies, we will have to resort to environmental effects. This will be the subject of a forthcoming paper.

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Distribution and kinematics of 26Al in the Galactic disc

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2125 ◽

2020 ◽

Vol 497 (2) ◽

pp. 2442-2454 ◽

Cited By ~ 2

Author(s):

Yusuke Fujimoto ◽

Mark R Krumholz ◽

Shu-ichiro Inutsuka

Keyword(s):

Star Formation ◽

Milky Way ◽

Spiral Structure ◽

Rotation Speed ◽

Scale Height ◽

Stellar Winds ◽

Galactic Disc ◽

Stellar Feedback ◽

Self Gravity ◽

Solar Position

ABSTRACT 26Al is a short-lived radioactive isotope thought to be injected into the interstellar medium (ISM) by massive stellar winds and supernovae (SNe). However, all-sky maps of 26Al emission show a distribution with a much larger scale height and faster rotation speed than either massive stars or the cold ISM. We investigate the origin of this discrepancy using an N-body + hydrodynamics simulation of a Milky-Way-like galaxy, self-consistently including self-gravity, star formation, stellar feedback, and 26Al production. We find no evidence that the Milky Way’s spiral structure explains the 26Al anomaly. Stars and the 26Al bubbles they produce form along spiral arms, but, because our simulation produces material arms that arise spontaneously rather than propagating arms forced by an external potential, star formation occurs at arm centres rather than leading edges. As a result, we find a scale height and rotation speed for 26Al similar to that of the cold ISM. However, we also show that a synthetic 26Al emission map produced for a possible Solar position at the edge of a large 26Al bubble recovers many of the major qualitative features of the observed 26Al sky. This suggests that the observed anomalous 26Al distribution is the product of foreground emission from the 26Al produced by a nearby, recent SN.

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The Supershell-Molecular Cloud Connection in the Milky Way and Beyond

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313000525 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 83-86

Author(s):

J. R. Dawson ◽

N. M. McClure-Griffiths ◽

Y. Fukui ◽

J. Dickey ◽

T. Wong ◽

...

Keyword(s):

Molecular Cloud ◽

Molecular Clouds ◽

Large Scale ◽

Milky Way ◽

Observational Evidence ◽

Cloud Formation ◽

Stellar Feedback ◽

The Relationship ◽

Global Contribution

AbstractThe role of large-scale stellar feedback in the formation of molecular clouds has been investigated observationally by examining the relationship between Hi and 12CO(J = 1−0) in supershells. Detailed parsec-resolution case studies of two Milky Way supershells demonstrate an enhanced level of molecularisation over both objects, and hence provide the first quantitative observational evidence of increased molecular cloud production in volumes of space affected by supershell activity. Recent results on supergiant shells in the LMC suggest that while they do indeed help to organise the ISM into over-dense structures, their global contribution to molecular cloud formation is of the order of only ∼ 10%.

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The artemis simulations: stellar haloes of Milky Way-mass galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2463 ◽

2020 ◽

Vol 498 (2) ◽

pp. 1765-1785 ◽

Cited By ~ 3

Author(s):

Andreea S Font ◽

Ian G McCarthy ◽

Robert Poole-Mckenzie ◽

Sam G Stafford ◽

Shaun T Brown ◽

...

Keyword(s):

High Resolution ◽

Galaxy Formation ◽

Large Scale ◽

Milky Way ◽

Mass Density ◽

Power Laws ◽

Stellar Feedback ◽

Radial Profiles ◽

Hydrodynamical Simulations

ABSTRACT We introduce the Assembly of high-ResoluTion Eagle-simulations of MIlky Way-type galaxieS (artemis) simulations, a new set of 42 zoomed-in, high-resolution (baryon particle mass of $\approx 2\times 10^4 \, {\rm M}_{\odot }\, h^{-1}$), hydrodynamical simulations of galaxies residing in haloes of Milky Way mass, simulated with the eagle galaxy formation code with re-calibrated stellar feedback. In this study, we analyse the structure of stellar haloes, specifically the mass density, surface brightness, metallicity, colour, and age radial profiles, finding generally very good agreement with recent observations of local galaxies. The stellar density profiles are well fitted by broken power laws, with inner slopes of ≈−3, outer slopes of ≈−4, and break radii that are typically ≈20–40 kpc. The break radii generally mark the transition between in situ formation and accretion-driven formation of the halo. The metallicity, colour, and age profiles show mild large-scale gradients, particularly when spherically averaged or viewed along the major axes. Along the minor axes, however, the profiles are nearly flat, in agreement with observations. Overall, the structural properties can be understood by two factors: that in situ stars dominate the inner regions and that they reside in a spatially flattened distribution that is aligned with the disc. Observations targeting both the major and minor axes of galaxies are thus required to obtain a complete picture of stellar haloes.

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The Milky Way: a halo, a corona, or both?

Symposium - International Astronomical Union ◽

10.1017/s0074180900242861 ◽

1985 ◽

Vol 106 ◽

pp. 415-420

Author(s):

Klaas S. De Boer

Keyword(s):

Transition Zone ◽

Equilibrium Model ◽

High Velocity ◽

Milky Way ◽

Galactic Plane ◽

Hydrostatic Equilibrium ◽

Hot Gas ◽

Halo Stars ◽

Intergalactic Space ◽

Gaseous Halo

The detection in absorption lines of gas clouds outside the galactic plane at high velocities by Münch and Zirin (1961), high velocities then defined as velocities differing by more than 20 km/s from the LSR, showed that the space outside the Milky-Way disk contains not just stars. Of course, from a continuity argument it had been all along clear that some transition zone had to exist between the dense (relatively speaking) gas of the Milky-Way plane and the vast (almost) emptiness of intergalactic space. The presence of these clouds requires a mechanism to prevent their evaporation, and Spitzer (1956) proposed that dilute hot gas had to exist outside the Milky-Way disk reaching, in his hydrostatic-equilibrium model, temperatures of a few million K at several tens of kpc. These high temperatures led him to name these gases the Galactic Corona. Observational confirmation of the abundance of these cool clouds came from the measurements of 21-cm HI emission, but no one-to-one correspondence with clouds detected in the visual did appear (Habing 1969). For the majority of the high-velocity (HV) clouds (Hulsbosch 1978) no distances are known, and all of those are believed to exist as a gaseous halo with the halo stars. Thus our Milky Way appears to have outside the disk: a halo, a gaseous halo, and a corona.

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The Complementary Roles of Feedback and Mergers in Building the Gaseous Halo and the X-Ray Corona of Milky-Way-sized Galaxies

The Astrophysical Journal ◽

10.3847/1538-4357/aae43a ◽

2018 ◽

Vol 867 (1) ◽

pp. 73 ◽

Cited By ~ 7

Author(s):

A. Sokołowska ◽

A. Babul ◽

L. Mayer ◽

S. Shen ◽

P. Madau

Keyword(s):

Milky Way ◽

X Ray ◽

Gaseous Halo

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On the Cooling Flow Problem in the Gaseous Halo of the Milky Way

The Astrophysical Journal ◽

10.3847/1538-4357/ab846c ◽

2020 ◽

Vol 894 (1) ◽

pp. 1 ◽

Cited By ~ 2

Author(s):

Xiang-Er Fang ◽

Fulai Guo ◽

Ye-Fei Yuan

Keyword(s):

Milky Way ◽

Flow Problem ◽

Cooling Flow ◽

Gaseous Halo

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Spatial Distribution of the Milky Way Hot Gaseous Halo Constrained by Suzaku X-Ray Observations

The Astrophysical Journal ◽

10.3847/1538-4357/aacceb ◽

2018 ◽

Vol 862 (1) ◽

pp. 34 ◽

Cited By ~ 19

Author(s):

Shinya Nakashima ◽

Yoshiyuki Inoue ◽

Noriko Yamasaki ◽

Yoshiaki Sofue ◽

Jun Kataoka ◽

...

Keyword(s):

Spatial Distribution ◽

Milky Way ◽

X Ray ◽

Gaseous Halo

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Diagnostics of gaseous halo of the Milky Way by a shock wave from the Galactic Centre

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz143 ◽

2019 ◽

Vol 484 (3) ◽

pp. 2954-2965 ◽

Cited By ~ 4

Author(s):

Yoshiaki Sofue

Keyword(s):

Shock Wave ◽

Milky Way ◽

Galactic Centre ◽

Gaseous Halo

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Short-lived radioisotopes in meteorites from Galactic-scale correlated star formation

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319001534 ◽

2018 ◽

Vol 14 (S345) ◽

pp. 83-86

Author(s):

Yusuke Fujimoto ◽

Mark R. Krumholz ◽

Shogo Tachibana

Keyword(s):

Star Formation ◽

Solar System ◽

Milky Way ◽

Normal Range ◽

Solar Abundance ◽

Outstanding Problem ◽

Stellar Feedback ◽

Hydrodynamical Simulation ◽

The Galaxy ◽

Supernova Explosions

AbstractMeteoritic evidence shows that the Solar system at birth contained significant quantities of short-lived radioisotopes (SLRs) such as 60Fe and 26Al produced in supernova explosions and in the Wolf-Rayet winds. Explaining how they travelled from these origin sites to the primitive Solar system before decaying is an outstanding problem. In this paper, we present a chemo-hydrodynamical simulation of the entire Milky Way to measure for the distribution of 60Fe/56Fe and 26Al/27Al ratios over all stars in the Galaxy. We show that the Solar abundance ratios are well within the normal range. We find that SLRs are abundant in newborn stars because star formation is correlated on Galactic scales, so that ejecta preferentially enrich atomic gas that will subsequently be accreted onto existing GMCs or will form new ones. Thus new generations of stars preferentially form in patches of the Galaxy contaminated by previous generations of stellar feedback.

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