The In Situ Origins of Dwarf Stellar Outskirts in FIRE-2

Kado-Fong, Erin; Sanderson, Robyn E.; Greene, Jenny E.; Cunningham, Emily C.; Wheeler, Coral; Chan, T. K.; El-Badry, Kareem; Hopkins, Philip F.; Wetzel, Andrew; Boylan-Kolchin, Michael; Faucher-Giguère, Claude-André; Huang, Song; Quataert, Eliot; Starkenburg, Tjitske K.

doi:10.3847/1538-4357/ac6c88

Cited by 11 publications

(12 citation statements)

References 112 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While the morphologies and kinematics of these FIRE-2 galaxies near MW masses (M star  10 10 M e ) and at much lower masses (M star  10 7 M e ) broadly agree with observations (e.g., et al 2017), at intermediate masses (M star ∼ 10 8−10 M e ) the FIRE-2 galaxies are insufficiently "disky," that is, too dispersion dominated, as compared with observations (El-Badry et al 2018aKado-Fong et al 2022). Related to this, nearly all FIRE-2 galaxies at M star ∼ 10 7−10 M e have extended sizes; essentially none of them form a compact, baryon-dominated, high-density stellar distribution, as observed in some galaxies at these masses (Garrison-Kimmel et al 2019a;Shen et al 2022).…”

Section: Known Tensions With Observationssupporting

confidence: 84%

Public Data Release of the FIRE-2 Cosmological Zoom-in Simulations of Galaxy Formation

Wetzel

Hayward

Sanderson

et al. 2023

ApJS

Self Cite

View full text Add to dashboard Cite

We describe a public data release of the FIRE-2 cosmological zoom-in simulations of galaxy formation (available at http://flathub.flatironinstitute.org/fire) from the Feedback In Realistic Environments (FIRE) project. FIRE-2 simulations achieve parsec-scale resolution to explicitly model the multiphase interstellar medium while implementing direct models for stellar evolution and feedback, including stellar winds, core-collapse and Type Ia supernovae, radiation pressure, photoionization, and photoelectric heating. We release complete snapshots from three suites of simulations. The first comprises 20 simulations that zoom in on 14 Milky Way (MW)–mass galaxies, five SMC/LMC-mass galaxies, and four lower-mass galaxies including one ultrafaint; we release 39 snapshots across z = 0–10. The second comprises four massive galaxies, with 19 snapshots across z = 1–10. Finally, a high-redshift suite comprises 22 simulations, with 11 snapshots across z = 5–10. Each simulation also includes dozens of resolved lower-mass (satellite) galaxies in its zoom-in region. Snapshots include all stored properties for all dark matter, gas, and star particles, including 11 elemental abundances for stars and gas, and formation times (ages) of star particles. We also release accompanying (sub)halo catalogs, which include galaxy properties and member star particles. For the simulations to z = 0, including all MW-mass galaxies, we release the formation coordinates and an “ex situ” flag for all star particles, pointers to track particles across snapshots, catalogs of stellar streams, and multipole basis expansions for the halo mass distributions. We describe publicly available python packages for reading and analyzing these simulations.

show abstract

Section: Known Tensions With Observationssupporting

confidence: 84%

Public Data Release of the FIRE-2 Cosmological Zoom-in Simulations of Galaxy Formation

Wetzel

Hayward

Sanderson

et al. 2023

ApJS

Self Cite

View full text Add to dashboard Cite

show abstract

“…In situ halo stars are known to contribute to the stellar halos in the Latte suite of simulations (Yu et al 2020;Ostdiek et al 2020;Santistevan et al 2021;Kado-Fong et al 2022), as well as other simulation suites (e.g., Zolotov et al 2009Zolotov et al , 2010). In the observations, halo stars are often interpreted as having potentially in situ origins if they have either (1) high-α abundances and relatively high metallicities, consistent with the thick disk, but eccentric orbits (e.g., Bonaca et al 2017;Belokurov et al 2020;Naidu et al 2020); or (2) high-α, metalpoor stars with more disk-like kinematics (i.e., the metal-poor, dynamically hot tail of the disk; e.g., Norris et al 1985 Venn et al 2020;Cordoni et al 2021).…”

Section: Appendix C Modeling Only Lower-mass Eventsmentioning

confidence: 99%

Reading the CARDs: The Imprint of Accretion History in the Chemical Abundances of the Milky Way's Stellar Halo

Cunningham

Sanderson

Johnston

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

In the era of large-scale spectroscopic surveys in the Local Group, we can explore using chemical abundances of halo stars to study the star formation and chemical enrichment histories of the dwarf galaxy progenitors of the Milky Way (MW) and M31 stellar halos. In this paper, we investigate using the chemical abundance ratio distributions (CARDs) of seven stellar halos from the Latte suite of FIRE-2 simulations. We attempt to infer galaxies’ assembly histories by modeling the CARDs of the stellar halos of the Latte galaxies as a linear combination of template CARDs from disrupted dwarfs, with different stellar masses M ⋆ and quenching times t 100. We present a method for constructing these templates using present-day dwarf galaxies. For four of the seven Latte halos studied in this work, we recover the mass spectrum of accreted dwarfs to a precision of <10%. For the fraction of mass accreted as a function of t 100, we find the residuals of 20%–30% for five of the seven simulations. We discuss the failure modes of this method, which arise from the diversity of star formation and chemical enrichment histories that dwarf galaxies can take. These failure cases can be robustly identified by the high model residuals. Although the CARDs modeling method does not successfully infer the assembly histories in these cases, the CARDs of these disrupted dwarfs contain signatures of their unusual formation histories. Our results are promising for using CARDs to learn more about the histories of the progenitors of the MW and M31 stellar halos.

show abstract

“…Nonetheless, the halo will still be dominated by relatively old (and hence metal-poor) stars, as these have experienced the largest number of perturbations necessary to produce significant heating effects (Stinson et al 2009;El-Badry et al 2016). Halos produced in this way are also expected to be more flattened in shape than accreted halos (McCarthy et al 2012;Kado-Fong et al 2022) and to display net prograde rotation (McCarthy et al 2012;Cooper et al 2015); though Tissera et al (2013) note a clear age dependence for this trend, with the oldest dynamically heated halo stars having no significant rotation.…”

Section: "In Situ" Mechanismsmentioning

confidence: 99%

“…Particularly in lower-mass galaxies, a variety of stellar feedback processes are thought to produce halo-like populations: shocked, outflowing gas can form new stars that inherit the underlying gas kinematics to produce kinematically hot populations (e.g., Stinson et al 2009;El-Badry et al 2016), and repeated inflow/outflow cycles due to bursty star formation can drive fluctuations in the global gravitational potential that heat stellar orbits and drive net outward migration of disk stars (e.g., Stinson et al 2009;Maxwell et al 2012;El-Badry et al 2016). Simulations and observations of stellar halos around massive galaxies suggest that each of these different formation mechanisms leaves distinct imprints on the properties-including mean age, metallicity, and kinematics (e.g., McCarthy et al 2012;Tissera et al 2013;Cooper et al 2015;El-Badry et al 2016;Kado-Fong et al 2022)-of the resultant "halo" population.…”

Section: Introductionmentioning

confidence: 99%

“…It is sufficiently massive that it should have experienced a number of mergers (e.g., Conselice et al 2008), which could produce a stellar halo either directly from accreted debris or associated disk heating. However, as a dwarf galaxy, it also falls into the regime where stellar feedback is expected to contribute significantly to the formation of a halo population (Kado-Fong et al 2022). Additionally, it possesses spiral arms, and recent results from a large Hubble Space Telescope (HST) survey strongly suggest the presence of a weak (∼1 kpc) bar structure (Lazzarini et al 2022;Smercina et al 2023) that could potentially contribute to disk heating and subsequent halo formation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

TREX: Kinematic Characterization of a High-dispersion Intermediate-age Stellar Component in M33

Cullinane,

Gilbert,

Guhathakurta

et al. 2023

ApJ

View full text Add to dashboard Cite

The dwarf galaxy Triangulum (M33) presents an interesting testbed for studying stellar halo formation: it is sufficiently massive so as to have likely accreted smaller satellites, but also lies within the regime where feedback and other “in situ” formation mechanisms are expected to play a role. In this work, we analyze the line-of-sight kinematics of stars across M33 from the TREX survey, with a view to understanding the origin of its halo. We split our sample into two broad populations of varying age, comprising 2032 “old” red giant branch stars and 671 “intermediate-age” asymptotic giant branch and carbon stars. We find decisive evidence for two distinct kinematic components in both the old and intermediate-age populations: a low-dispersion (∼22 km s−1) disk-like component corotating with M33's H i gas and a significantly higher-dispersion component (∼50–60 km s−1) that does not rotate in the same plane as the gas and is thus interpreted as M33's stellar halo. While kinematically similar, the fraction of stars associated with the halo component differs significantly between the two populations: this is consistently ∼10% for the intermediate-age population, but decreases from ∼34% to ∼10% as a function of radius for the old population. We additionally find evidence that the intermediate-age halo population is systematically offset from the systemic velocity of M33 by ∼25 km s−1, with a preferred central LOS velocity of ∼ − 155 km s−1. This is the first detection and characterization of an intermediate-age halo in M33, and suggests in situ formation mechanisms, as well as potentially tidal interactions, have helped shaped it.

show abstract

The In Situ Origins of Dwarf Stellar Outskirts in FIRE-2

Cited by 11 publications

References 112 publications

Public Data Release of the FIRE-2 Cosmological Zoom-in Simulations of Galaxy Formation

Public Data Release of the FIRE-2 Cosmological Zoom-in Simulations of Galaxy Formation

Reading the CARDs: The Imprint of Accretion History in the Chemical Abundances of the Milky Way's Stellar Halo

TREX: Kinematic Characterization of a High-dispersion Intermediate-age Stellar Component in M33

Contact Info

Product

Resources

About