Can radial motions in the stellar halo constrain the rate of change of mass in the Galaxy?

Abstract

A change in the mass of the Galaxy with time will leave its imprint on the motions of the stars, with stars having radially outward (mass loss) or inward (mass accretion) bulk motions. Here we test the feasibility of using the mean radial motion of stars in the stellar halo to constrain the rate of change of mass in the Galaxy, for example, due to decay of dark matter into invisible dark sector particles or more conservatively from the settling of baryons. In the current $\Lambda$CDM paradigm of structure formation, the stellar halo is formed by accretion of satellites onto the host galaxy. Over time, as the satellites disrupt and phase mix, the mean radial motion $⟨V_R⟩$ of the stellar halo is eventually expected to be close to zero. But most halos have substructures due to incomplete mixing of specific accretion events and this can lead to nonzero $⟨V_R⟩$ in them. Using simulations, we measure the mean radial motion, $⟨V_R⟩$, of stars in 13 $\Lambda$CDM stellar halos lying in a spherical shell of radius 30 kpc. We find that for most halos, the shell motion is quite small, with 75\% of halos having $⟨V_R⟩\lesssim 1.2\mathrm{km}{s}^{-1}$. When substructures are removed by using a clustering algorithm, $⟨V_R⟩$ is reduced even further, with 75\% of halos having $⟨V_R⟩\lesssim 0.6\mathrm{km}{s}^{-1}$. A value of $⟨V_R⟩\approx 0.6\mathrm{km}{s}^{-1}$ can be attained corresponding to a galactic mass loss rate of 2\% per Gyr. We show that this can place constraints on dark matter decay parameters such as the decay lifetime and the kick velocity that is imparted to the daughter particle. The advent of all-sky stellar surveys involving millions to billions of stars is encouraging for detecting signatures of dark matter decay.

References in corpus (58)

• In the Realm of the Hubble tension $-$ a Review of Solutions
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Dark Matter Candidates from Particle Physics and Methods of Detection
• Dark Energy Survey Year 1 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing
• Concentrations of Dark Halos from their Assembly Histories
• FIRE-2 Simulations: Physics versus Numerics in Galaxy Formation
• Tracing Galaxy Formation with Stellar Halos I: Methods
• Early Dark Energy Can Resolve The Hubble Tension
• How supernova feedback turns dark matter cusps into cores
• Scalar Dark Matter candidates
• Reconciling dwarf galaxies with LCDM cosmology: Simulating a realistic population of satellites around a Milky Way-mass galaxy
• The GALAH+ Survey: Third Data Release
• A dynamically young and perturbed Milky Way disk
• Gaia Data Release 2: Mapping the Milky Way disc kinematics
• Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories
• Galaxia: a code to generate a synthetic survey of the Milky Way
• 4MOST: Project overview and information for the First Call for Proposals
• The Universal Mass Accretion History of CDM Haloes
• A review of indirect searches for particle dark matter
• Footprints of the Sagittarius dwarf galaxy in the $Gaia$ data set
• Review of LHC Dark Matter Searches
• Current status of direct dark matter detection experiments
• The stellar halo of the Galaxy
• The Influence of Sagittarius and the Large Magellanic Cloud on the Milky Way Galaxy
• The GALAH survey and Gaia DR2: dissecting the stellar disc's phase space by age, action, chemistry and location
• Large Scale Structure Tests of Warm Dark Matter
• PAMELA data and leptonically decaying dark matter
• Current Dark Matter Annihilation Constraints from CMB and Low-Redshift Data
• A fresh look at linear cosmological constraints on a decaying dark matter component
• Late universe decaying dark matter can relieve the H_0 tension
• Checking the dark matter origin of 3.53 keV line with the Milky Way center
• Decaying Dark Matter and the PAMELA Anomaly
• Discovery of a 3.5 keV line in the Galactic Center and a Critical Look at the Origin of the Line Across Astronomical Targets
• Bending and Breathing Modes of the Galactic Disk
• Novel constraints on the particle nature of dark matter from stellar streams
• Alleviating the $H_0$ and ${\sigma }_8$ anomalies with a decaying dark matter model
• Synthetic Gaia surveys from the FIRE cosmological simulations of Milky Way-mass galaxies
• Dark Energy at early times and ACT: a larger Hubble constant without late-time priors
• The GALAH survey and Gaia DR2: Linking ridges, arches and vertical waves in the kinematics of the Milky Way
• Detection of the LMC-induced sloshing of the Galactic halo
• Cosmological Simulations of Decaying Dark Matter: Implications for Small-scale Structure of Dark Matter Halos
• Cosmological implications of supersymmetric axion models
• Linear cosmological constraints on 2-body decaying dark matter scenarios and the $S_8$ tension
• Multi-Dimensional Density Estimation and Phase Space Structure Of Dark Matter Halos
• Cosmic-ray Antinuclei as Messengers of New Physics: Status and Outlook for the New Decade
• Decaying Hidden Gauge Boson and the PAMELA and ATIC/PPB-BETS Anomalies
• Group finding in the stellar halo using M-giants in 2MASS: An extended view of the Pisces Overdensity?
• Questioning a 3.5 keV dark matter emission line
• Dark-matter decays and Milky Way satellite galaxies
• The GALAH Survey: Accurate Radial Velocities and Library of Observed Stellar Template Spectra
• Do you smell something decaying? Updated linear constraints on decaying dark matter scenarios
• DM halo morphological types of MW-like galaxies in the TNG50 simulation: Simple, Twisted, or Stretched
• Group Finding in the Stellar Halo using Photometric Surveys: Current Sensitivity and Future Prospects
• Decaying Dark Matter and the Deficit of Dwarf Haloes
• Decay of multiple dark matter particles to dark radiation in different epochs does not alleviate the Hubble tension
• Can ultralight dark matter explain the age-velocity dispersion relation of the Milky Way disc: A revised and improved treatment
• 4MOST Consortium Survey 1: The Milky Way Halo Low-Resolution Survey
• The GALAH Survey: Velocity fluctuations in the Milky Way using red clump giants

Cited by in corpus (2)

• Constraints on late-forming exploding black holes
• Probing the spatial and velocity anisotropies in stellar halos from the Aquarius simulations