The information content in cold stellar streams

Abstract

Cold stellar streams---produced by tidal disruptions of clusters---are long-lived, coherent dynamical features in the halo of the Milky Way. Due to their different ages and different positions in phase space, different streams tell us different things about the Galaxy. Here we employ a Cramer--Rao (CRLB) or Fisher-matrix approach to understand the quantitative information content in eleven known streams (ATLAS, GD-1, Hermus, Kwando, Orinoco, PS1A, PS1C, PS1D, PS1E, Sangarius and Triangulum). This approach depends on a generative model, which we have developed previously, and which permits calculation of derivatives of predicted stream properties with respect to Galaxy and stream parameters. We find that in simple analytic models of the Milky Way, streams on eccentric orbits contain the most information about the halo shape. For each stream, there are near-degeneracies between dark-matter-halo properties and parameters of the bulge, the disk, and the stream progenitor, but simultaneous fitting of multiple streams will constrain all parameters at the percent level. At this precision, simulated dark matter halos deviate from simple analytic parametrizations, so we add an expansion of basis functions to give the gravitational potential more freedom. As freedom increases, the information about the halo reduces overall, and it becomes more localized to the current position of the stream. In the limit of high model freedom, a stellar stream appears to measure the local acceleration at its current position; this motivates thinking about future non-parametric approaches. The CRLB formalism also permits us to assess the value of future measurements of stellar velocities, distances, and proper motions. We show that kinematic measurements of stream stars are essential for producing competitive constraints on the distribution of dark matter, which bodes well for stream studies in the age of Gaia.

submitted to AAS journals, comments welcome

References in corpus (27)

• The NumPy array: a structure for efficient numerical computation
• The Gaia mission
• galpy: A Python Library for Galactic Dynamics
• The DESI Experiment Part I: Science,Targeting, and Survey Design
• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• Detection of a 63 Degree Cold Stellar Stream in the Sloan Digital Sky Survey
• Stellar Streams Discovered in the Dark Energy Survey
• "Skinny Milky Way, Please", says Sagittarius
• Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5
• The shape of the inner Milky Way halo from observations of the Pal 5 and GD-1 stellar streams
• A Synoptic Map of Halo Substructures from the Pan-STARRS1 3π Survey
• Generation of mock tidal streams
• Milky Way Mass and Potential Recovery Using Tidal Streams in a Realistic Halo
• Dipping Our Toes in the Water: First Models of GD-1 as a Stream
• Findings of the Joint Dark Energy Mission Figure of Merit Science Working Group
• Discovery of a cold stellar stream in the ATLAS DR1 data
• Inferring the gravitational potential of the Milky Way with a few precisely measured stars
• Bayesian Mass Estimates of the Milky Way II: The dark and light sides of parameter assumptions
• The Milky Way Tomography with SDSS. V. Mapping the Dark Matter Halo
• Hubble Space Telescope Proper Motions along the Sagittarius Stream: I. Observations and Results for Stars in Four Fields
• Two New Halo Debris Streams in the Sloan Digital Sky Survey
• At a Crossroads: Stellar Streams in the South Galactic Cap
• A dynamics-free lower bound on the mass of our galaxy
• Galaxy halo expansions: a new biorthogonal family of potential-density pairs
• The Super-NFW model: an analytic dynamical model for cold dark matter haloes and elliptical galaxies
• Tails from the Orphanage

Cited by in corpus (76)

• The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
• The Spur and the Gap in GD-1: Dynamical evidence for a dark substructure in the Milky Way halo
• Ghostly Tributaries to the Milky Way: Charting the Halo's Stellar Streams with the Gaia DR2 catalogue
• Gaia Proper Motions and Orbits of the Ultra-Faint Milky Way Satellites
• Overview of the DESI Milky Way Survey
• The mass of our Milky Way
• The Southern Stellar Stream Spectroscopic Survey ($S^5$): Overview, Target Selection, Data Reduction, Validation, and Early Science
• The DECam Local Volume Exploration Survey: Overview and First Data Release
• $S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream
• $S^5$: The Orbital and Chemical Properties of One Dozen Stellar Streams
• Orbital Clustering Identifies the Origins of Galactic Stellar Streams
• Mining for Dark Matter Substructure: Inferring subhalo population properties from strong lenses with machine learning
• Proper Motions of Stellar Streams Discovered in the Dark Energy Survey
• The effect of the LMC on the Milky Way system
• Variations in the width, density, and direction of the Palomar 5 tidal tails
• Merger-induced galaxy transformations in the ARTEMIS simulations
• Dynamical Evolution of Multiple-Population Globular Clusters
• The Dragonfly Wide Field Survey. I. Telescope, Survey Design and Data Characterization
• Multiple components of the Jhelum stellar stream
• Weighing the Galactic disk using phase-space spirals II. Most stringent constraints to a thin dark disk using Gaia EDR3
• Kinematics of the Palomar 5 stellar stream from RR Lyrae stars
• C18O, 13CO, and 12CO abundances and excitation temperatures in the Orion B molecular cloud: An analysis of the precision achievable when modeling spectral line within the Local Thermodynamic Equilibrium approximation
• The S2 Stream: the shreds of a primitive dwarf galaxy
• First Results on Dark Matter Substructure from Astrometric Weak Lensing
• An extended Pal 5 stream in Gaia DR2
• Dragonfly imaging of the galaxy NGC5907: a revised view of the iconic stellar stream
• Identifying RR Lyrae Variable Stars in Six Years of the Dark Energy Survey
• The hidden past of M92: Detection and characterization of a newly formed 17° long stellar stream using the Canada-France Imaging Survey
• Mapping Dark Matter with Extragalactic Stellar Streams: the Case of Centaurus A
• The Hough Stream Spotter: A New Method for Detecting Linear Structure in Resolved Stars and Application to the Stellar Halo of M31
• Orbital Torus Imaging: Using Element Abundances to Map Orbits and Mass in the Milky Way
• Constraining the Gravitational Potential from the Projected Morphology of Extragalactic Tidal Streams
• The impact of a massive Sagittarius dSph on GD-1-like streams
• Shapes of Milky-Way-Mass Galaxies with Self-Interacting Dark Matter
• Discovery of Extended Tidal Tails around the Globular Cluster Palomar 13
• Discovery of a new nearby globular cluster with extreme kinematics located in the extension of a halo stream
• The Power of Halometry
• A new calibration method of sub-halo orbital evolution for semi-analytic models
• A chemo-dynamical link between the Gjöll stream and NGC 3201
• Models of Distorted and Evolving Dark Matter Halos
• On the Use of Field RR Lyrae as Galactic Probes. V. Optical and radial velocity curve templates
• The course of the Orphan Stream in the Northern Galactic Hemisphere traced with Gaia DR2
• Information content of BP/RP spectra in Gaia DR3
• DELVE-ing into the Jet: a thin stellar stream on a retrograde orbit at 30 kpc
• The dark side of FIRE: predicting the population of dark matter subhaloes around Milky Way-mass galaxies
• Uncovering fossils of the distant Milky Way with UNIONS: NGC 5466 and its stellar stream
• 1-DREAM: 1D Recovery, Extraction and Analysis of Manifolds in noisy environments
• Charting Galactic Accelerations with Stellar Streams and Machine Learning
• The Extended Tidal Tails of NGC 7089 (M2)
• A Larger Extent for the Ophiuchus Stream
• A giant thin stellar stream in the Coma Galaxy Cluster
• Hunting ghosts: the iconic stellar stream(s) around NG5907 under scrutiny
• Evidence for C and Mg variations in the GD-1 stellar stream
• Statistical properties of substructures around Milky Way-sized haloes and their implications for the formation of stellar streams
• Prospects for Detecting Gaps in Globular Cluster Stellar Streams in External Galaxies with the Nancy Grace Roman Space Telescope
• A Cold Stellar Stream in Pegasus
• Dating the tidal disruption of globular clusters with Gaia data on their stellar streams
• Trojan globular clusters: radial migration via trapping in bar resonances
• The Multiple Extended Tidal Tails of NGC 288
• A Ghost in Boötes: The Least Luminous Disrupted Dwarf Galaxy
• Gaps in stellar streams as a result of globular cluster fly-bys
• First measurement of the triaxiality of the inner dark matter halo of the Milky Way
• Estimate of the Mass and Radial Profile of the Orphan-Chenab Stream's Dwarf Galaxy Progenitor Using MilkyWay@home
• STRRINGS: STReams in Residual Images of Nearby GalaxieS
• The information on halo properties contained in spectroscopic observations of late-type galaxies
• Mapping the Milky Way in 5-D with 170 Million Stars
• Building an Acceleration Ladder with Tidal Streams and Pulsar Timing
• Orbital phase-driven biases in Galactic mass constraints from stellar streams
• On the Fast Track: Rapid construction of stellar stream paths
• One Stream or Two -- Exploring Andromeda's North West Stream
• Inferring the density and membership of stellar streams with flexible models: The GD-1 stream in Gaia Data Release 3
• The Influence of Subhaloes on Host Halo Properties
• The Sagittarius stellar stream embedded in a fermionic dark matter halo
• Constraining the population of dark matter halo shapes using hierarchical inference with extragalactic stellar streams
• rrlfe: Software for Generating and Applying Metallicity Calibrations for RR Lyrae Variable Stars Across a Wide Range of Phases and Temperatures
• Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way