Dynamically constraining the length of the Milky Way bar

Lucey, Madeline; Pearson, Sarah; Hunt, Jason A. S.; Hawkins, Keith; Ness, Melissa; Petersen, Michael; Price-Whelan, Adrian M.; Weinberg, Martin D.

doi:10.48550/arxiv.2206.01798

Cited by 3 publications

(1 citation statement)

References 76 publications

(109 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is now well known that the Milky Way has a central bar of approximately 3 to 5 kpc across (e.g. Lucey et al 2022). In a future paper we intend to explore the impact of a central rotating bar on the chevrons, particularly at low galactocentric radii.…”

Section: Impact Of Lmc and Sgrmentioning

confidence: 98%

Ironing the folds: the phase space chevrons of a GSE-like merger as a dark matter subhalo detector

Vasiliev

Belokurov

et al. 2022

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Recent work uncovered features in the phase space of the Milky Way’s stellar halo which may be attributed to the last major merger. When stellar material from a satellite is accreted onto its host, it phase mixes and appears finely substructured in phase space. For a high-eccentricity merger, this substructure most clearly manifests as numerous wrapping chevrons in (vr, r) space, corresponding to stripes in (E, θr) space. We introduce the idea of using this substructure as an alternative subhalo detector to cold stellar streams. We simulate an N-body merger akin to the GSE and assess the impact of subhaloes on these chevrons. We examine how their deformation depends on the mass, pericentre, and number of subhaloes. To quantify the impact of perturbers in our simulations, we utilise the appearance of chevrons in (E, θr) space to introduce a new quantity – the ironing parameter. We show that: (1) a single flyby of a massive (∼1010 M⊙) subhalo with pericentre comparable to, or within, the shell’s apocentre smooths out the substructure, (2) a single flyby of a low mass (≲ 108 M⊙) has negligible effect, (3) multiple flybys of subhalos derived from a subhalo mass function between 107 − 1010 M⊙ cause significant damage if deep within the potential, (4) the effects of known perturbers (e.g. Sagittarius) should be detectable and offer constraints on their initial mass. The sensitivity to the populations of subhaloes suggests that we should be able to place an upper limit on the Milky Way’s subhalo mass function.

show abstract

Section: Impact Of Lmc and Sgrmentioning

confidence: 98%

Ironing the folds: the phase space chevrons of a GSE-like merger as a dark matter subhalo detector

Vasiliev

Belokurov

et al. 2022

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

Measuring the dynamical length of galactic bars

Petersen,

Weinberg,

Katz

2024

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We define a physically-motivated measure for galactic bar length, called the dynamical length. The dynamical length of the bar corresponds to the radial extent of the trapped orbits that are the backbone supporting the bar feature. We propose a direct observational technique well suited to integral field unit spectroscopy to measure it. Identifying these orbits and using the dynamical length is a more faithful tracer of the secular evolution and influence of the bar. We demonstrate the success of our observational technique for recovering the maximal bar-parenting orbit in a range of simulations, and to show its promise we perform its measurement on a real galaxy. We also study the difference between traditionally used ellipse fit approaches to determine bar length and the dynamical length proposed here in a wide range of bar-forming N-body simulations of a stellar disc and dark matter halo. We find that ellipse fitting may severely overestimate measurements of the bar length by a factor of 1.5-2.5 relative to the extent of the orbits that are trapped and actually comprise the bar. This bias leads to overestimates of both bar mass and the ratio of corotation radius to bar length, i.e. the bar speed, affecting inferences about the evolution of bars in the real universe.

show abstract

Ironing the folds: The phase space chevrons of a GSE-like merger as a dark matter subhalo detector

Davies,

Vasiliev,

Belokurov

et al. 2022

Preprint

View full text Add to dashboard Cite

Recent work uncovered features in the phase space of the Milky Way's stellar halo which may be attributed to the last major merger. When stellar material from a satellite is accreted onto its host, it phase mixes and appears finely substructured in phase space. For a high-eccentricity merger, this substructure most clearly manifests as numerous wrapping chevrons in (𝑣 𝑟 , 𝑟) space, corresponding to stripes in (𝐸, 𝜃 𝑟 ) space. We introduce the idea of using this substructure as an alternative subhalo detector to cold stellar streams. We simulate an N-body merger akin to the GSE and assess the impact of subhaloes on these chevrons. We examine how their deformation depends on the mass, pericentre, and number of subhaloes. To quantify the impact of perturbers, we utilise the appearance of chevrons in (𝐸, 𝜃 𝑟 ) space to introduce a new quantity -the ironing parameter. We show that: (1) a single flyby of a massive (∼ 10 10 M ) subhalo with pericentre comparable to, or within, the shell's apocentre smooths out the substructure, (2) a single flyby of a low mass ( 10 8 M ) has negligible effect, (3) multiple flybys of subhalos derived from a subhalo mass function between 10 7 − 10 10 M cause significant damage if deep within the potential, (4) the effects of known perturbers (e.g. Sagittarius) should be detectable and offer constraints on their initial mass. The sensitivity to the populations of subhaloes suggests that we should be able to place an upper limit on the Milky Way's subhalo mass function.

show abstract

Dynamically constraining the length of the Milky Way bar

Cited by 3 publications

References 76 publications

Ironing the folds: the phase space chevrons of a GSE-like merger as a dark matter subhalo detector

Ironing the folds: the phase space chevrons of a GSE-like merger as a dark matter subhalo detector

Measuring the dynamical length of galactic bars

Ironing the folds: The phase space chevrons of a GSE-like merger as a dark matter subhalo detector

Contact Info

Product

Resources

About