On the Stability of Tidal Streams in Action Space

Arora, Arpit; Sanderson, Robyn E.; Panithanpaisal, Nondh; Cunningham, Emily C.; Wetzel, Andrew; Garavito-Camargo, Nicolás

doi:10.3847/1538-4357/ac93fb

Cited by 16 publications

(9 citation statements)

References 99 publications

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“…The properties of the LMC analogs selected for this work are detailed in Table 2. We emphasize that the distinction in LMC mass ratios is critical, because the mass ratio at pericenter is a key indicator with which a potential can be accurately modeled in terms of axisymmetry, and it may impact the galaxy-halo alignment (Arora et al 2022). In reality, Arora et al (2022) find that the MW-LMC mass ratio is high enough such that loworder axisymmetric multipole modeling is insufficient in describing the galactic potential.…”

Section: Methodsmentioning

confidence: 97%

Orientations of Dark Matter Halos in FIRE-2 Milky Way–mass Galaxies

Baptista,

Sanderson,

Huber

et al. 2023

ApJ

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The shape and orientation of dark matter (DM) halos are sensitive to the microphysics of the DM particles, yet in many mass models, the symmetry axes of the Milky Way’s DM halo are often assumed to be aligned with the symmetry axes of the stellar disk. This is well motivated for the inner DM halo, but not for the outer halo. We use zoomed-in cosmological baryonic simulations from the Latte suite of FIRE-2 Milky Way–mass galaxies to explore the evolution of the DM halo’s orientation with radius and time, with or without a major merger with a Large Magellanic Cloud analog, and when varying the DM model. In three of the four cold DM halos we examine, the orientation of the halo minor axis diverges from the stellar disk vector by more than 20° beyond about 30 galactocentric kpc, reaching a maximum of 30°–90°, depending on the individual halo’s formation history. In identical simulations using a model of self-interacting DM with σ = 1 cm2 g−1, the halo remains aligned with the stellar disk out to ∼200–400 kpc. Interactions with massive satellites (M ≳ 4 × 1010 M ⊙ at pericenter; M ≳ 3.3 × 1010 M ⊙ at infall) affect the orientation of the halo significantly, aligning the halo’s major axis with the satellite galaxy from the disk to the virial radius. The relative orientation of the halo and disk beyond 30 kpc is a potential diagnostic of self-interacting DM, if the effects of massive satellites can be accounted for.

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Section: Methodsmentioning

confidence: 97%

Orientations of Dark Matter Halos in FIRE-2 Milky Way–mass Galaxies

Baptista,

Sanderson,

Huber

et al. 2023

ApJ

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“…In order to examine the uncertainties on the Milky Way stream orbits due to the assumption of a time-independent potential, we also integrate the orbits of the FIRE streams from the Latte simulations in a time-independent potential. We use the potential models from Arora et al (2022), fit via basis function expansion to the host galaxy potential in each of the Latte simulations at z = 0. We integrate the orbits using AGAMA (Vasiliev 2019).…”

Section: Appendix C Comparison Of Orbit Integration Methodsmentioning

confidence: 99%

“…We then compute the orbits of the FIRE streams by individually tracing the orbits of each member star through the saved snapshots, and then integrating the orbit around each pericenter using the code AGAMA (Vasiliev 2019). We integrate each star particle in the corresponding host galaxy potential at the snapshot closest to the most recent pericentric passage, 29 using the models from Arora et al (2022). 30 These models are fit to each snapshot, and consist of multipole expansions (up to l = 4), computed using a combination of spherical harmonics and azimuthal harmonics for the halo and disk, respectively.…”

Section: Stellar Streams In Firementioning

confidence: 99%

Streams on FIRE: Populations of Detectable Stellar Streams in the Milky Way and FIRE

Shipp

Panithanpaisal

Necib

et al. 2023

ApJ

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We present the first detailed comparison of populations of dwarf galaxy stellar streams in cosmological simulations and the Milky Way. In particular, we compare streams identified around 13 Milky Way analogs in the FIRE-2 simulations to streams observed by the Southern Stellar Stream Spectroscopic Survey (S 5). For an accurate comparison, we produce mock Dark Energy Survey (DES) observations of the FIRE streams and estimate the detectability of their tidal tails and progenitors. The number and stellar mass distributions of detectable stellar streams is consistent between observations and simulations. However, there are discrepancies in the distributions of pericenters and apocenters, with the detectable FIRE streams, on average, forming at larger pericenters (out to >110 kpc) and surviving only at larger apocenters (≳40 kpc) than those observed in the Milky Way. We find that the population of high-stellar-mass dwarf galaxy streams in the Milky Way is incomplete. Interestingly, a large fraction of the FIRE streams would only be detected as intact satellites in DES-like observations, since their tidal tails have too low surface brightness to be detectable. We thus predict a population of yet-undetected tidal tails around Milky Way satellites, as well as a population of fully undetected low-surface-brightness stellar streams, and estimate their detectability with the Rubin Observatory. Finally, we discuss the causes and implications of the discrepancies between the stream populations in FIRE and the Milky Way, and explore future avenues for tests of satellite disruption in cosmological simulations.

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“…This yields the mean normalized orbital energy 〈E − E 200 〉. Furthermore, the potential (Φ), taken from Arora et al (2022), is comprised of three components: an NFW profile for the dark matter halo (Navarro et al 1996), a spherical potential model for the central bulge, and a Miyamoto-Nagai profile modeling the cylindrical disk of the simulation (Miyamoto & Nagai 1975). This potential is then propagated in simulation time as a time-evolving multipole potential, modeled using a low-order multipole expansion assuming axisymmetry, evaluated at each snapshot independently.…”

Section: Orbital Energymentioning

confidence: 99%

“…These values were computed using the potentials determined inArora et al (2022), utilizing the AGAMA Vasiliev (2019) galactic dynamics package.…”

mentioning

confidence: 99%

The Observable Properties of Galaxy Accretion Events in Milky Way–like Galaxies in the FIRE-2 Cosmological Simulations

Horta

Cunningham

Sanderson

et al. 2023

ApJ

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In the Λ-Cold Dark Matter model of the universe, galaxies form in part through accreting satellite systems. Previous works have built an understanding of the signatures of these processes contained within galactic stellar halos. This work revisits that picture using seven Milky Way–like galaxies in the Latte suite of FIRE-2 cosmological simulations. The resolution of these simulations allows a comparison of contributions from satellites aboveM * ≳ 10 × 7 M ⊙, enabling the analysis of observable properties for disrupted satellites in a fully self-consistent and cosmological context. Our results show that the time of accretion and the stellar mass of an accreted satellite are fundamental parameters that in partnership dictate the resulting spatial distribution, orbital energy, and [α/Fe]-[Fe/H] compositions of the stellar debris of such mergers at present day. These parameters also govern the resulting dynamical state of an accreted galaxy at z = 0, leading to the expectation that the inner regions of the stellar halo (R GC ≲ 30 kpc) should contain fully phase-mixed debris from both lower- and higher-mass satellites. In addition, we find that a significant fraction of the lower-mass satellites accreted at early times deposit debris in the outer halo (R GC > 50 kpc) that are not fully phased-mixed, indicating that they could be identified in kinematic surveys. Our results suggest that, as future surveys become increasingly able to map the outer halo of our Galaxy, they may reveal the remnants of long-dead dwarf galaxies whose counterparts are too faint to be seen in situ in higher-redshift surveys.

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On the Stability of Tidal Streams in Action Space

Cited by 16 publications

References 99 publications

Orientations of Dark Matter Halos in FIRE-2 Milky Way–mass Galaxies

Orientations of Dark Matter Halos in FIRE-2 Milky Way–mass Galaxies

Streams on FIRE: Populations of Detectable Stellar Streams in the Milky Way and FIRE

The Observable Properties of Galaxy Accretion Events in Milky Way–like Galaxies in the FIRE-2 Cosmological Simulations

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