Stellar proper motions in the outskirts of classical dwarf spheroidal galaxies with<i>Gaia</i>EDR3

Qi, Yuewen; Zivick, Paul; Pace, Andrew B.; Riley, A. H.; Strigari, Louis E.

doi:10.1093/mnras/stac805

Cited by 12 publications

(10 citation statements)

References 95 publications

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“…The Vast Polar Orbital structure and orbital poles alignment may be caused by the LMC (Garavito-Camargo et al 2021) but Pawlowski et al (2021) show the magnitude of the LMC perturbation is to small to fully explain the Vast Polar Orbital structure. Overall, we find excellent agreement between our results and other Gaia EDR3 proper motion results 3 (Mc-Connachie & Venn 2020b; Li et al 2021;Martínez-García et al 2021;Vitral 2021;Battaglia et al 2022;Qi et al 2022). In particular, McConnachie & Venn (2020b); Battaglia et al (2022) apply similar mixture models based on spatial position and proper motion with an additional color-magnitude component based on Gaia photometry.…”

Section: Is Orientation a Signature Of Tidal Disruption?supporting

confidence: 86%

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Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies

Pace¹,

Erkal²,

Li³

2022

Preprint

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We measure systemic proper motion of 52 dwarf spheroidal (dSph) satellite galaxies of the Milky Way (MW). We combine Gaia EDR3 astrometry with accurate photometry and utilize a probabilistic mixture model to determine the systemic proper motions and identify likely dSph members. For the 46 dSphs with literature line-of-sight velocities we compute orbits in both a MW and a combined MW + Large Magellanic Cloud (LMC) potential and identify likely LMC satellites. For these orbits, we Monte Carlo sample over the observational uncertainties for each dSph as well as the uncertainties in the MW and LMC potentials. We explore orbital parameters and previously used diagnostics for probing the MW tidal influence on the dSph population. We find that signatures of tidal influence by the MW are easily seen by comparing a dSph's pericenter and its average density relative to the MW at its pericenter. dSphs with large ellipticity show a preference for their orbital direction to align with their major axis even if they do not have a small pericenter. We compare the radial orbital phase of our dSph sample to subhalos in MW-like N -body simulations and find that the distributions are similar and that there is not an excess of satellites near their pericenter. With future Gaia data releases, we find that the orbital precision of most dSphs will be limited by uncertainties in distance and/or the MW potential rather than proper motion precision. Finally, we provide our membership lists to enable community follow-up.

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Section: Is Orientation a Signature Of Tidal Disruption?supporting

confidence: 86%

“…This will enable future spectroscopic followup. To enable the search for distant members, we recompute our membership analysis without the spatial component and only use the proper motion posterior (e.g., Chiti et al 2020;Qi et al 2022) and include these membership probabilities in Appendix A.…”

Section: Proper Motionsmentioning

confidence: 99%

Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies

Pace¹,

Erkal²,

Li³

2022

Preprint

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show abstract

“…This will enable future spectroscopic follow-up. To enable the search for distant members, we recompute our membership analysis without the spatial component and only use the proper motion posterior (e.g., Chiti et al 2020;Qi et al 2022) and include these membership probabilities in Appendix A.…”

Section: Proper Motionsmentioning

confidence: 99%

Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies

Pace

Erkal

2022

ApJ

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We combine Gaia early data release 3 astrometry with accurate photometry and utilize a probabilistic mixture model to measure the systemic proper motion of 52 dwarf spheroidal (dSph) satellite galaxies of the Milky Way (MW). For the 46 dSphs with literature line-of-sight velocities we compute orbits in both a MW and a combined MW + Large Magellanic Cloud (LMC) potential and identify Car II, Car III, Hor I, Hyi I, Phx II, and Ret II as likely LMC satellites. 40% of our dSph sample has a >25% change in pericenter and/or apocenter with the MW + LMC potential. For these orbits, we use a Monte Carlo sample for the observational uncertainties for each dSph and the uncertainties in the MW and LMC potentials. We predict that Ant II, Boo III, Cra II, Gru II, and Tuc III should be tidally disrupting by comparing each dSph's average density relative to the MW density at its pericenter. dSphs with large ellipticity (CVn I, Her, Tuc V, UMa I, UMa II, UMi, Wil 1) show a preference for their orbital direction to align with their major axis even for dSphs with large pericenters. We compare the dSph radial orbital phase to subhalos in MW-like N-body simulations and infer that there is not an excess of satellites near their pericenter. With projections of future Gaia data releases, we find that dSph's orbital precision will be limited by uncertainties in the distance and/or MW potential rather than in proper motion precision. Finally, we provide our membership catalogs to enable community follow-up.

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“…EDR3 (Sohn et al 2017;McConnachie & Venn 2020a;Vitral 2021;Li et al 2021;Battaglia et al 2022;Qi et al 2022;Pace et al 2022), which could explain this discrepancy.…”

Section: Observed Velocity Gradientsmentioning

confidence: 99%

Tidally induced velocity gradients in the Milky Way dwarf spheroidal satellites

Martínez-García¹,

Pino²,

Aparicio³

2022

Preprint

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We present a kinematic study of six dwarf spheroidal galaxies (dSph) satellites of the Milky Way (MW), namely Carina, Draco, Fornax, Sculptor, Sextans, and Ursa Minor. We combine proper motions (PMs) from the Gaia Data Release 3 (DR3) and lineof-sight velocities (𝑣 los ) from the literature to derive their 3D internal kinematics and to study the presence of internal velocity gradients. We find significant velocity gradients along the line-of-sight for Carina, Draco, Fornax, and Ursa Minor. The value of such gradients appears to be related to the orbital history of the dwarfs, indicating that the interaction with the Milky Way (MW) is causing them. Dwarfs that are close to the MW and moving towards their orbits pericentres show, on average, larger velocity gradients. On the other hand, dwarfs that have recently left their orbits pericentres show no significant gradients. Lastly, dwarfs located at large Galactocentric distances show gradients with an intermediate intensity. Our results would indicate that the torque caused by the strong tidal forces exerted by the MW induces a strong velocity gradient when the dwarfs approach their orbits pericentres. During the pericentre passage, the rapid change in the forces direction would disrupt such gradient, which may steadily recover as the galaxies recede. We assess our findings by analyzing dwarfs satellites from the TNG50 simulation. We find a significant increase in the intensity of the detected gradients as the satellites approach their pericentre, followed by a sharp drop as they abandon it, supporting our results for the dSphs of the MW.

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Stellar proper motions in the outskirts of classical dwarf spheroidal galaxies withGaiaEDR3

Cited by 12 publications

References 95 publications

Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies

Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies

Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies

Tidally induced velocity gradients in the Milky Way dwarf spheroidal satellites

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