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We measure the spatial density of F turnoff stars in the Sagittarius dwarf tidal stream, from Sloan Digital Sky Survey (SDSS) data, using statistical photometric parallax. We find a set of continuous, consistent parameters that describe the…

Motivated by recent observations of the Sagittarius stream, we devise a rapid algorithm to generate faithful representations of the centroids of stellar tidal streams formed in a disruption of a progenitor of an arbitrary mass in an…

Astrophysics of Galaxies · Physics 2014-11-03 S. L. J. Gibbons , V. Belokurov , N. W. Evans

Standard cosmology predicts that dwarfs were the first galaxies to be formed in the Universe and that many of them merge afterwards to form bigger galaxies such as the Milky Way. This process would have left behind traces such as tidal…

Upcoming ground and space-based surveys are poised to illuminate low surface brightness tidal features, providing a new observable connection to dark matter physics. From imaging of tidal debris, the morphology of stellar streams can be…

Astrophysics of Galaxies · Physics 2026-04-08 Jacob Nibauer , Sarah Pearson

We present a data-driven method for reconstructing the galactic acceleration field from phase-space measurements of stellar streams. Our approach is based on a flexible and differentiable fit to the stream in phase-space, enabling a direct…

Astrophysics of Galaxies · Physics 2023-03-31 Jacob Nibauer , Vasily Belokurov , Miles Cranmer , Jeremy Goodman , Shirley Ho

The Milky Way's satellites provide unique information about the density of the Galactic halo at large radii. The inclusion of even a few rather inaccurate proper motions resolves an ambiguity in older mass estimates in favour of higher…

Astrophysics · Physics 2007-05-23 James Binney

Recent maps of the halo using RR Lyrae from Pan-STARRS1 have clearly depicted the spatial structure of the Sagittarius stream. These maps show the leading and trailing stream apocenters differ in galactocentric radius by a factor of two,…

Cold dark matter halos are expected to be triaxial and often tilted relative to the stellar disk. Stellar streams provide a sensitive tracer of the Milky Way's halo shape, though models for the Galactic potential are typically limited to…

Astrophysics of Galaxies · Physics 2025-04-11 Jacob Nibauer , Ana Bonaca

We discuss a sample of over 3000 candidate RR Lyrae stars selected by various methods using Sloan Digital Sky Survey data for about 1000 deg^2 of sky. These stars probe the halo structure out to ~100 kpc from the Galactic center. Their…

Dynamically cold stellar streams are ideal probes of the gravitational field of the Milky Way. This paper re-examines the question of how such streams might be used to test for the presence of "missing satellites" -the many thousands of…

Astrophysics of Galaxies · Physics 2015-05-20 Joo Heon Yoon , Kathryn V. Johnston , David W. Hogg

Stellar tidal streams are a key tracer of galaxy evolution and have the potential to provide an indirect means for tracing dark matter. For the Local Group, many diffuse substructures have been identified and their link to galaxy evolution…

ESA's Global Astrometric Interferometer for Astrophysics (GAIA) holds the promise of mapping out the detailed phase space structure of the Galactic halo by providing unprecedented annual proper motion and parallax of $1-10\muas$ astrometric…

Astrophysics · Physics 2007-05-23 HongSheng Zhao , Kathryn Johnston , Lars Hernquist , David Spergel

A method to search for tidal streams and to fit their orbits based on maximum likelihood is presented and applied to the Gaia data. Tests of the method are performed showing how a simulated stream produced by tidal stripping of a star…

Astrophysics of Galaxies · Physics 2020-10-28 C. G. Palau , J. Miralda-Escudé

Stellar halo substructures were identified using statistical photometric parallax of blue main sequence turnoff stars from fourteen Sloan Digital Sky Survey stripes in the north Galactic cap. Four structures are consistent with previous…

Astrophysics of Galaxies · Physics 2018-10-31 Jake Weiss , Heidi Jo Newberg , Travis Desell

We present a model for producing tidal streams from disrupting progenitors in arbitrary potentials, utilizing the idea that the majority of stars escape from the progenitor's two Lagrange points. The method involves releasing test particles…

Astrophysics of Galaxies · Physics 2015-06-23 A. Bowden , V. Belokurov , N. W. Evans

We examine the detectability and interpretation of debris trails caused by satellite disruption in external galaxies using semi-analytic approximations for the dependence of streamer length, width and surface brightness on satellite and…

Astrophysics · Physics 2009-11-06 Kathryn V. Johnston , Penny D. Sackett , James S. Bullock

Stellar streams are sensitive tracers of the gravitational potential, which is typically assumed to be static in the inner Galaxy. However, massive mergers like Gaia-Sausage-Enceladus can impart torques on the stellar disk of the Milky Way…

Astrophysics of Galaxies · Physics 2023-12-18 Jacob Nibauer , Ana Bonaca , Mariangela Lisanti , Denis Erkal , Zoe Hastings

We assemble a catalogue of candidate Sagittarius stream members with 5d and 6d phase-space information, using astrometric data from Gaia DR2, distances estimated from RR Lyrae stars, and line-of-sight velocities from various spectroscopic…

Astrophysics of Galaxies · Physics 2021-02-22 Eugene Vasiliev , Vasily Belokurov , Denis Erkal

We use cosmological N-body simulations from the Aquarius Project to study the tidal effects of a dark matter halo on the shape and orientation of its substructure. Although tides are often assumed to enhance asphericity and to stretch…

Astrophysics of Galaxies · Physics 2015-06-23 Christopher Barber , Else Starkenburg , Julio F. Navarro , Alan W. McConnachie

How do galaxies move relative to one another? While we can examine the motion of dark matter subhalos around their hosts in simulations of structure formation, determining the orbits of satellites around their parent galaxies from…

Astrophysics of Galaxies · Physics 2015-10-21 David Hendel , Kathryn V. Johnston