Signatures of resonance and phase mixing in the Galactic disc

Hunt, Jason A. S.; Bub, Mathew W.; Bovy, Jo; Mackereth, J. Ted; Trick, Wilma H.; Kawata, Daisuke

doi:10.1093/mnras/stz2667

Cited by 82 publications

(94 citation statements)

References 66 publications

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“…There is more than one feature in the local kinematics that looks like the bar OLR's velocity flip. But only one can be the true OLR (if at all visible) and the others will be related to other bar resonances (e.g., Monari et al 2019a;Hunt & Bovy 2018;Asano et al 2020) and spiral arms (De Simone et al 2004;Chakrabarty 2007;Quillen et al 2018;Michtchenko et al 2018;Hunt et al 2019;Khoperskov et al 2020;Hunt et al 2020). Our angle-based method provides additional constraining evidence.…”

Section: Comparing the Action-and Angle-based Methods For The Olrmentioning

confidence: 94%

“…(A) Chiba et al (2019) have studied a decelerating bar model-as opposed to the often used bar models with a constant pattern speed-which creates signatures that could indeed be closer to the observed ones around the 'Sirius' moving group with the current OLR at the 'Hat'. (B) Spiral arm models can create ridges just as strong as those observed in the Gaia data (e.g., De Simone et al 2004;Antoja et al 2009;Sellwood et al 2019;Hunt et al 2019). Work by Quillen et al (2018) and Khoperskov et al (2020) associates the main features we see in the local data not with the bar resonances, but with the MW's spiral arms as identified by Reid et al (2014) and Xu et al (2016): the 'Hat' to the Perseus arm (see also Hunt et al 2017), 'Sirius' to the Local Arm, the 'Horn' (at ( , ) ∼ (50, −20) km/s) to the Sagittarius arm, 'Hercules' to the Scutum arm.…”

Section: Introductionmentioning

confidence: 92%

“…The precision and accuracy of the stellar velocities measured by the Gaia satellite's second data release (DR2, Gaia Collaboration et al 2018a;Katz et al 2019) have made local moving groups visible in unprecedented detail (Gaia Collaboration et al 2018b). Several authors have noted that the 'Hat' moving group at ∼ 40 km/s could look like an OLR also-in this case caused by a slow bar (Monari et al 2019b;Hunt et al 2019;Trick et al 2019a).…”

Section: Introductionmentioning

confidence: 99%

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Identifying resonances of the Galactic bar in Gaia DR2: I. Clues from action space

Trick

Fragkoudi

Hunt

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Action space synthesizes the orbital information of stars and is well-suited to analyse the rich kinematic substructure of the disc in the Gaia DR2 radial velocity sample (RVS). We revisit the strong perturbation induced in the Milky Way (MW) disc by an m = 2 bar, using test particle simulations and the actions (JR, Lz, Jz) estimated in an axisymmetric potential. These make three useful diagnostics cleanly visible. (1.) We use the well-known characteristic flip from outward to inward motion at the Outer Lindblad Resonance (OLR, l = +1, m = 2), which occurs along the axisymmetric resonance line (ARL) in (Lz, JR), to identify in the Gaia action data three candidates for the bar’s OLR and pattern speed Ωbar: 1.85Ω0, 1.20Ω0, and 1.63Ω0 (with ∼0.1Ω0 systematic uncertainty). The Gaia data is therefore consistent with both slow and fast bar models in the literature, but disagrees with recent measurements of ∼1.45Ω0. (2.) For the first time, we demonstrate that bar resonances—especially the OLR—cause a gradient in vertical action 〈Jz〉 with Lz around the ARL via “Jz-sorting” of stars. This could contribute to the observed coupling of 〈vR〉 and 〈|vz|〉 in the Galactic disc. (3.) We confirm prior results that the behaviour of resonant orbits is well approximated by scattering and oscillation in (Lz, JR) along a slope ΔJR/ΔLz = l/m centered on the l:m ARL. Overall, we demonstrate that axisymmetrically estimated actions are a powerful diagnostic tool even in non-axisymmetric systems.

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Section: Comparing the Action-and Angle-based Methods For The Olrmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Identifying resonances of the Galactic bar in Gaia DR2: I. Clues from action space

Trick

Fragkoudi

Hunt

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…While we showed that the barred Galactic model of Portail et al (2017) can reproduce most of the observed features of the local velocity and action space, many of these can be explained by different combinations of non-axisymmetric perturbations, making their modelling degenerate, as recently shown by, e.g., Hunt et al (2019). For instance, if the Sun is located just outside of the bar's outer 2:1 Lindblad resonance, Hercules is caused by the linear deformation of velocity space.…”

Section: Following Hercules In Azimuthmentioning

confidence: 55%

Constraining the Milky Way non-axisymmetries with Gaia

et al. 2019

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The unprecedented amount and accuracy of kinematic data from the second release of the Gaia mission have started revolutionizing our understanding of the dynamics of the Milky Way disk. The detailed stellar velocity field in the Galactic disk should allow us to constrain with unprecedented precision the parameters of the non-axisymmetric modes of the disk. We present here the status of our current modelling efforts in this area, and their implication on the dynamics of the Galactic bar in particular.

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“…In the local interarm, we see different trails at different locations around the Sun's position in the Local Armlet ( Fig. 2 in Hunt et al 2019).…”

Section: Legitimacy Of a Short Interarm Island Between Cygnus And Pementioning

confidence: 93%

Interarm islands in the Milky Way – the one near the Cygnus spiral arm

Vallée

2020

Monthly Notices of the Royal Astronomical Society

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This study extends to the structure of the Galaxy. Our main goal is to focus on the first spiral arm beyond the Perseus arm, often called the Cygnus arm or the 'Outer Norma' arm, by appraising the distributions of the masers near the Cygnus arm. The method is to employ masers whose trigonometric distances were measured with accuracy. The maser data come from published literaturesee column 8 in Table 1 here, having been obtained via the existing networks ( US VLBA , the Japanese VERA, the European VLBI, and the Australian LBA). The new results for Cygnus are split in two groups: those located near a recent CO-fitted global model spiral arm, and those congregating within an 'interarm island' located halfway between the Perseus arm and the Cygnus arm. Next, we compare this island with other similar interarm objects near other spiral arms. Thus we delineate an interarm island (6x2 kpc) located between the two long spiral arms (Cygnus and Perseus arms); this is reminiscent of the small 'Local Orion arm' (4x2 kpc) found earlier between the Perseus and Sagittarius arms, and of the old 'Loop' (2x0.5 kpc) found earlier between the Sagittarius and Scutum arms. Various arm models are compared, based on observational data (masers, HII regions, HI gas, young stars, CO 1-0 gas).

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Signatures of resonance and phase mixing in the Galactic disc

Cited by 82 publications

References 66 publications

Identifying resonances of the Galactic bar in Gaia DR2: I. Clues from action space

Identifying resonances of the Galactic bar in Gaia DR2: I. Clues from action space

Constraining the Milky Way non-axisymmetries with Gaia

Interarm islands in the Milky Way – the one near the Cygnus spiral arm

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