Linking the brightest stellar streams with the accretion history of Milky Way like galaxies

Vera-Casanova, A; Gómez, Facundo A.; Monachesi, Antonela; Gargiulo, Ignacio D.; Pallero, Diego; Grand, Robert J. J.; Marinacci, Federico; Pakmor, Rüdiger; Simpson, Christine M.; Frenk, Carlos S.; Morales, Gustavo

doi:10.1093/mnras/stac1636

“…Many of these systems are predicted to be detectable in LSST. In addition, these imaging surveys will uncover populations of stellar streams around external galaxies (e.g., Pearson et al 2019;Vera-Casanova et al 2022) and enable similar tests with a larger sample of galaxies.…”

Section: Discussionmentioning

confidence: 99%

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

Shipp

¹

,

Panithanpaisal

²

,

Necib

³

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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“…Stellar halos of Milky Way-like galaxies have become objects of interest in the astronomical community, and various studies regarding them have been carried out in recent years (e.g., Zolotov et al 2009;Cooper et al 2010;Tissera et al 2014;Peacock et al 2015;Monachesi et al 2016aMonachesi et al , 2016bRey & Starkenburg 2022;Vera-Casanova et al 2022). These halos can be considered to be a consequence of the hierarchical formation of structures of the ΛCDM model (Searle & Zinn 1978;Frenk et al 1988;Navarro et al 1997) because stars can be found in the external regions of these massive galaxies, principally due to the interactions between subhalos.…”

Section: Introductionmentioning

confidence: 99%

Extended Stellar Populations in Ultrafaint Dwarf Galaxies

Tau,

Vivas,

Martínez-Vázquez

2024

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The possible existence of stellar halos in low-mass galaxies is being intensely discussed nowadays after some recent discoveries of stars located in the outskirts of dwarf galaxies of the Local Group. RR Lyrae stars can be used to identify the extent of these structures, taking advantage of the minimization of foreground contamination they provide. In this work we use RR Lyrae stars obtained from Gaia DR3, the Dark Energy Survey, the Zwicky Transient Facility, and Pan-STARRS1 to explore the outskirts of 45 ultrafaint dwarf galaxies. We associate the stars with a host galaxy based on their angular separations, magnitudes, and proper motions. We find a total of 120 RR Lyrae stars that belong to 21 different galaxies in our sample. We report seven new RR Lyrae stars in six ultrafaint dwarf galaxies (Hydrus I, Ursa Major I, Ursa Major II, Grus II, Eridanus II, and Tucana II). We found a large number of new possible members in Bootes I and Bootes III as well, but some of them may actually belong to the nearby Sagittarius stream. Adding to our list of 120 RR Lyrae stars the observations of other ultrafaint dwarf galaxies that were beyond the reach of our search, we find that at least 10 of these galaxies have RR Lyrae stars located at distances greater than four times their respective half-light radius, which implies that at least 33% of the 30 ultrafaint dwarfs with a population of RR Lyrae stars have extended stellar populations.

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“…Past mergers also leave behind a morphological record in the form of various post-merger features, which can be the result of major mergers-which is typically the case for plumes (e.g., Lauer 1988) and tidal tails (e.g., Pfleiderer 1963;Toomre & Toomre 1972)-or minor mergers, which usually produce streams (e.g., Johnston et al 1999) or shells (e.g., Malin & Carter 1983;Quinn 1984). By examining these signatures, it is possible to infer a galaxy's recent interaction history and thereby disentangle the role of various merging processes governing galaxy properties (e.g., Johnston et al 2008;Martínez-Delgado et al 2009;Spavone et al 2020;Vera-Casanova et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Distribution of Merging and Post-merger Galaxies in Nearby Galaxy Clusters

Kim,

Sheen,

Jaffé

et al. 2024

ApJ

0

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We study the incidence and spatial distribution of galaxies that are currently undergoing gravitational merging (M) or that have signs of being post-merger (PM) in six galaxy clusters (A754, A2399, A2670, A3558, A3562, and A3716) within the redshift range of 0.05 ≲ z ≲0.08. To this aim, we obtained Dark Energy Camera mosaics in the u ′ , g ′ , and r ′ bands covering up to 3 × R 200 of the clusters, reaching 28 mag arcsec−2 surface brightness limits. We visually inspect u ′ g ′ r ′ color-composite images of volume-limited (M r < −20) cluster member galaxies to identify whether galaxies are of M or PM type. We find 4% M-type and 7% PM-type galaxies in the galaxy clusters studied. By adding spectroscopic data and studying the projected phase-space diagram (PPSD) of the projected clustocentric radius and the line-of-sight velocity, we find that PM-type galaxies are more virialized than M-type galaxies, having a 1%–5% higher fraction within the escape-velocity region, while the fraction of M-type was ∼10% higher than the PM type in the intermediate environment. Similarly, on a substructure analysis, M types were found in groups in the outskirts, while PM-type populated groups were found in ubiquitous regions of the PPSD. Adopting literature-derived dynamical state indicator values, we observed a higher abundance of M types in dynamically relaxed clusters. This finding suggests that galaxies displaying post-merger features within clusters likely merged in low-velocity environments, including clusters outskirts and dynamically relaxed clusters.

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Linking the brightest stellar streams with the accretion history of Milky Way like galaxies

Cited by 9 publications

References 73 publications

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

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

Extended Stellar Populations in Ultrafaint Dwarf Galaxies

Distribution of Merging and Post-merger Galaxies in Nearby Galaxy Clusters

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