Magellanic satellites in ΛCDM cosmological hydrodynamical simulations of the Local Group

Santos-Santos, Isabel; Fattahi, Azadeh; Sales, Laura V.; Navarro, Julio F.

doi:10.1093/mnras/stab1020

Cited by 41 publications

(29 citation statements)

References 64 publications

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“…10 shows the predictions for the satellite population of isolated dwarf galaxies with stellar mass comparable to that of the LMC (M * ∼ 3 × 10 9 M ) , or, more precisely, dwarf primaries inhabiting halos with V200 in the range 50 to 100 km/s. This is consistent with the virial mass range (2.5 < M200/10 10 M < 45) of galaxies with comparable stellar mass in the APOSTLE simulations (see; e.g., Santos-Santos et al 2021). These authors use kinematic information to identify LMC-associated dwarfs; their list of most likely LMC satellites include 7 satellites: the SMC, Hydrus 1, Horologium 1, Carina 3, Tucana 4, Reticulum 2, and Phoenix 2 (dashed black line).…”

Section: Satellites Of Isolated Lmc-like Dwarfssupporting

confidence: 88%

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Satellite mass functions and the faint end of the galaxy mass-halo mass relation in LCDM

Santos-Santos¹,

Sales²,

Fattahi³

et al. 2021

Preprint

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The abundance of the faintest galaxies provides insight into the nature of dark matter and the process of dwarf galaxy formation. In the LCDM scenario, low mass halos are so numerous that the efficiency of dwarf formation must decline sharply with decreasing halo mass in order to accommodate the relative scarcity of observed dwarfs and satellites in the Local Group. The nature of this decline contains important clues to the mechanisms regulating the onset of galaxy formation in the faintest systems. We explore here two possible models for the stellar mass (M * )-halo mass (M 200 ) relation at the faint end, motivated by some of the latest LCDM cosmological hydrodynamical simulations. One model includes a sharp mass threshold below which no luminous galaxies form, as expected if galaxy formation proceeds only in systems above the Hydrogen-cooling limit. In the second model, M * scales as a steep power-law of M 200 with no explicit cutoff, as suggested by recent semianalytic work. Although both models predict satellite numbers around Milky Way-like galaxies consistent with current observations, they predict vastly different numbers of ultra-faint dwarfs and of satellites around isolated dwarf galaxies. Our results illustrate how the satellite mass function around dwarfs may be used to probe the M * -M 200 relation at the faint end and to elucidate the mechanisms that determine which low-mass halos "light up" or remain dark in the LCDM scenario.

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Section: Satellites Of Isolated Lmc-like Dwarfssupporting

confidence: 88%

“…The first panel additionally shows the satellite stellar mass function of MW-mass analogs observed as part of the SAGA survey(Mao et al 2020). For the case of the LMC, we show model results assuming V 200 = 50 (colored, solid) as well as 100 (colored, long-dashed) km/s, compared to likely Magellanic satellites according toSantos-Santos et al (2021).…”

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confidence: 99%

Satellite mass functions and the faint end of the galaxy mass-halo mass relation in LCDM

Santos-Santos¹,

Sales²,

Fattahi³

et al. 2021

Preprint

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“…While group infall does not seem to play a role in the tidal stripping of these dwarfs, which can be seen to start occurring only after infall, we note it here as a plausible mechanism of 'pre-processing' a satellite galaxy, prior to it crossing the virial radius of the host. Santos-Santos et al ( 2021 ) have shown that Large Magellanic Cloud (LMC)-like objects are twice as likely in Local Group-like environments (14 out of 24 host galaxies in APOSTLE have an LMC analogue) than in isolated galaxies. Pre-processed satellites of LMC-like objects can ultimately contribute to the dwarf population in the Milky Way.…”

Section: The DI V Erse F Ormation Histories Of F Ornax Analoguesmentioning

confidence: 99%

Can tides explain the low dark matter density in Fornax?

Genina

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Fattahi

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The low dark matter density in the Fornax dwarf galaxy is often interpreted as being due to the presence of a constant density ‘core’, but it could also be explained by the effects of Galactic tides. The latter interpretation has been disfavoured because it is apparently inconsistent with the orbital parameters and star formation history of Fornax. We revisit these arguments with the help of the APOSTLE cosmological hydrodynamics simulations. We show that simulated dwarfs with similar properties to Fornax are able to form stars after infall, so that star formation is not necessarily a good tracer of infall time. We also examine the constraints on the pericentre of Fornax and point out that small pericentres (<50 kpc) are not currently ruled out by the data, allowing for Fornax to be tidally influenced on its current orbit. Furthermore, we find that some dwarfs with large orbital pericentres can be stripped prior to infall due to interactions with more massive galaxies. Tidal effects lead to a reduction in the dark matter density, while the profile remains cuspy. Navarro-Frenk-White profiles are consistent with the kinematic data within 3σ in the innermost regions, while profiles with shallow cusps or cores provide a better fit. We predict that if the reduction of the dark matter density in Fornax occurs, at least in part, because of the action of Galactic tides, then tidal tails should be visible with a surface brightness limit of ∼35 − 36 mag arcsec−2 over a survey area of ≳100 deg2.

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“…In the absence of a dynamical association, group infall does not seem to be a suitable explanation for their similarities in orbital planes. Note, however, that other recent works-while also concluding that an association with the LMC of these two dwarf galaxies, particularly of Fornax, is unlikely-cannot firmly rule out such an association using current data [51,121].…”

Section: Group Infallmentioning

confidence: 74%

Phase-Space Correlations among Systems of Satellite Galaxies

Pawlowski

2021

Galaxies

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Driven by the increasingly complete observational knowledge of systems of satellite galaxies, mutual spatial alignments and relations in velocities among satellites belonging to a common host have become a productive field of research. Numerous studies have investigated different types of such phase-space correlations and were met with varying degrees of attention by the community. The Planes of Satellite Galaxies issue is maybe the best-known example, with a rich field of research literature and an ongoing, controversial debate on how much of a challenge it poses to the ΛCDM model of cosmology. Another type of correlation, the apparent excess of close pairs of dwarf galaxies, has received considerably less attention despite its reported tension with ΛCDM expectations. With the fast expansion of proper motion measurements in recent years, largely driven by the Gaia mission, other peculiar phase-space correlations have been uncovered among the satellites of the Milky Way. Examples are the apparent tangential velocity excess of satellites compared to cosmological expectations, and the unexpected preference of satellites to be close to their pericenters. At the same time, other kinds of correlations have been found to be more in line with cosmological expectations—specifically, lopsided satellite galaxy systems and the accretion of groups of satellite galaxies. The latter has mostly been studied in cosmological simulations thus far, but it offers the potential to address some of the other issues by providing a way to produce correlations among the orbits of a group’s satellite galaxy members. This review is the first to provide an introduction to the highly active field of phase-space correlations among satellite galaxy systems. The emphasis is on summarizing existing, recent research and highlighting interdependencies between the different, currently almost exclusively individually considered types of correlations. Future prospects in light of upcoming observational facilities and our ever-expanding knowledge of satellite galaxy systems beyond the Local Group are also briefly discussed.

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Magellanic satellites in ΛCDM cosmological hydrodynamical simulations of the Local Group

Cited by 41 publications

References 64 publications

Satellite mass functions and the faint end of the galaxy mass-halo mass relation in LCDM

Satellite mass functions and the faint end of the galaxy mass-halo mass relation in LCDM

Can tides explain the low dark matter density in Fornax?

Phase-Space Correlations among Systems of Satellite Galaxies

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