Generation of mock tidal streams

Fardal, Mark A.; Huang, Shuiyao; Weinberg, Martin D.

doi:10.1093/mnras/stv1198

Cited by 96 publications

(126 citation statements)

References 48 publications

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“…When S15 concluded that the progenitor of the Ophiuchus stream could not have been on its current orbit (measured by S15) for more than ∼400 Myr, they assumed the stream is on a regular, non-resonant orbit. However, as we already mentioned in Section 1, fanning can be a signature of a stream on a chaotic orbit (Fardal et al 2015;Price-Whelan et al 2016). If the fanning of the Ophiuchus stream is due to the stream being on a chaotic orbit, then the orbital parameters measured by S15 today were likely different in the past 12 Gyr.…”

Section: Discussionmentioning

confidence: 87%

“…This fanning may arise if the progenitor is on a chaotic orbit, common in triaxial or otherwise complex gravitational potentials (bottom panels of Figure 11 of Fardal et al 2015; Figure 7 of Price-Whelan et al 2015); or it may arise through interactions with dark matter subhalos (bottom left panel of Figure 3 of Bonaca et al 2014). Hence, stream-fanning-if observable-could become a new tool for studying these dynamical phenomena.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of Fanning in the Ophiuchus Stream

Sesar

Price-Whelan

Cohen

et al. 2015

ApJL

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The Ophiuchus stellar stream presents a dynamical puzzle: its old stellar populations (∼12 Gyr) cannot be reconciled with (1) its orbit in a simple model for the Milky Way potential and (2) its short angular extent, both of which imply that the observed stream formed within the last 1 Gyr < . Recent theoretical work has shown that streams on chaotic orbits may abruptly fan out near their apparent ends; stars in these fans are dispersed in both position and velocity and may be difficult to associate with the stream. Here we present the first evidence of such stream-fanning in the Ophiuchus stream, traced by four blue horizontal branch stars beyond the apparent end of the stream. These stars stand out from the background by their high velocities (v 230 los > km s −1 ) against ∼40 other stars: their velocities are comparable to those of the stream, but would be exceptional if they were unrelated halo stars. Their positions and velocities are, however, inconsistent with simple extrapolation of the observed cold, high-density portion of the stream. These observations suggest that stream-fanning may be a real, observable effect and, therefore, that Ophiuchus may be on a chaotic orbit. They also show that the Ophiuchus stream is more extended and hence dynamically older than previously thought, easing the stellar population versus dynamical age tension.

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Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Evidence of Fanning in the Ophiuchus Stream

Sesar

Price-Whelan

Cohen

et al. 2015

ApJL

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“…However, the observational constraints on Herc are not sufficient for such a complex approach. The same holds true for a more complex model of Herc with additional model parameters for, e.g., rotation of the progenitor (Amor- (Fardal, Huang & Weinberg 2015). Given the low number of observational constraints, we would likely be over-fitting our data without getting meaningful constraints on the model parameters.…”

Section: Streakline Model Setupmentioning

confidence: 86%

Exploding Satellites—the Tidal Debris of the Ultra-Faint Dwarf Galaxy Hercules

Küpper

Johnston

Mieske

et al. 2017

ApJ

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The ultra-faint satellite galaxy Hercules has a strongly elongated and irregular morphology with detections of tidal features up to 1.3 deg (3 kpc) from its center. This suggests that Hercules may be dissolving under the Milky Way's gravitational influence, and hence could be a tidal stream in formation rather than a bound, dark-matter dominated satellite. Using Bayesian inference in combination with N -body simulations, we show that Hercules has to be on a very eccentric orbit ( ≈ 0.95) within the Milky Way in this scenario. On such an orbit, Hercules "explodes" as a consequence of the last tidal shock at pericenter 0.5 Gyr ago. It is currently decelerating towards apocenter of its orbit with a velocity of V = 157 km s −1 -of which 99% is directed radially outwards. Due to differential orbital precession caused by the non-spherical nature of the Galactic potential, its debris fans out nearly perpendicular to its orbit. This explains why Hercules has an elongated shape without showing a distance gradient along its main body: it is in fact a stream that is significantly broader than it is long. In other words, it is moving perpendicular to its apparent major axis. In this scenario, there is a spike in the radial velocity profile created by the dominant debris component that formed through the last pericenter passage. This is similar to kinematic substructure that is observed in the real Hercules. Modeling a satellite on such a highly eccentric orbit is strongly dependent on the form of the Galactic potential. We therefore propose that detailed kinematic investigation of Hercules and other exploding satellite candidates can yield strong constraints on the potential of the Milky Way.

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“…This means that mass loss due to subhalo shocking on the progenitor is rare, and that the orbits of the particles that are bound to the progenitor should be irrelevant. Therefore, rather than treating the progenitor and stream as an N-body system, "shortcut" methods (e.g., Küpper et al 2012;Bonaca et al 2014;Gibbons et al 2014;Fardal et al 2015) which eject test particles at the progenitor's Lagrange points are promising alternatives. These methods potentially allow realistic streams to be generated quickly, so they are worth adopting in the future.…”

Section: Stream Progenitor and Orbitsmentioning

confidence: 99%

Dispersal of Tidal Debris in a Milky-Way-Sized Dark Matter Halo

Ngan

Carlberg

Bozek

et al. 2016

ApJ

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We simulate the tidal disruption of a collisionless N-body globular star cluster in a total of 300 different orbits selected to have galactocentric radii between 10 and 30 kpc in four dark matter halos: (a) a spherical halo with no subhalos, (b) a spherical halo with subhalos, (c) a realistic halo with no subhalos, and (d) a realistic halo with subhalos. This allows us to isolate and study how the halo's (lack of) dynamical symmetry and substructures affect the dispersal of tidal debris. The realistic halos are constructed from the snapshot of the Via Lactea II simulation at redshift zero. We find that the overall halo's symmetry disperses tidal debris to make the streams fluffier, consistent with previous studies of tidal debris of dwarf galaxies in larger orbits than ours in this study. On the other hand, subhalos in realistic potentials can locally enhance the densities along streams, making streams denser than their counterparts in smooth potentials. We show that many long and thin streams can survive in a realistic and lumpy halo for a Hubble time. This suggests that upcoming stellar surveys will likely uncover more thin streams which may contain density gaps that have been shown to be promising probes for dark matter substructures.

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Generation of mock tidal streams

Cited by 96 publications

References 48 publications

Evidence of Fanning in the Ophiuchus Stream

Evidence of Fanning in the Ophiuchus Stream

Exploding Satellites—the Tidal Debris of the Ultra-Faint Dwarf Galaxy Hercules

Dispersal of Tidal Debris in a Milky-Way-Sized Dark Matter Halo

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