scholarly journals Exploring Halo Substructure with Giant Stars. X. Extended Dark Matter or Tidal Disruption?: The Case for the Leo I Dwarf Spheroidal Galaxy

2007 ◽  
Vol 663 (2) ◽  
pp. 960-989 ◽  
Author(s):  
Sangmo Tony Sohn ◽  
Steven R. Majewski ◽  
Ricardo R. Munoz ◽  
William E. Kunkel ◽  
Kathryn V. Johnston ◽  
...  
Keyword(s):  
Dark Matter ◽  
Tidal Disruption ◽  
Giant Stars

scholarly journals Gamma-Ray Sensitivity to Dark Matter Subhalo Modelling at High Latitudes

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 90 ◽  
Author(s):  
Francesca Calore ◽  
Moritz Hütten ◽  
Martin Stref
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Point Sources ◽  
Large Set ◽  
Case Scenario ◽  
Tidal Disruption ◽  
Dwarf Spheroidal Galaxies ◽  
Dark Matter Mass ◽  
The One

Searches for “dark” subhaloes in gamma-ray point-like source catalogues are among promising strategies for indirect dark matter detection. Such a search is nevertheless affected by uncertainties related, on the one hand, to the modelling of the dark matter subhalo distribution in Milky-Way-like galaxies, and, on the other hand, to the sensitivity of gamma-ray instruments to the dark matter subhalo signals. In the present work, we assess the detectability of dark matter subhaloes in Fermi-LAT catalogues, taking into accounts uncertainties associated with the modelling of the galactic subhalo population. We use four different halo models bracketing a large set of uncertainties. For each model, adopting an accurate detection threshold of the LAT to dark matter subhalo signals and comparing model predictions with the number of unassociated point-sources in Fermi-LAT catalogues, we derive upper limits on the annihilation cross section as a function of dark matter mass. Our results show that, even in the best-case scenario (i.e., DMonly subhalo model), which does not include tidal disruption from baryons, the limits on the dark matter parameter space are less stringent than current gamma-ray limits from dwarf spheroidal galaxies. Comparing the results obtained with the different subhalo models, we find that baryonic effects on the subhalo population are significant and lead to dark matter constraints that are less stringent by a factor of ∼2 to ∼5. This uncertainty comes from the unknown resilience of dark matter subhaloes to tidal disruption.

scholarly journals Tidal disruption of fuzzy dark matter subhalo cores

2018 ◽  
Vol 97 (6) ◽  
Author(s):  
Xiaolong Du ◽  
Bodo Schwabe ◽  
Jens C. Niemeyer ◽  
David Bürger
Keyword(s):  
Dark Matter ◽  
Tidal Disruption

scholarly journals Remnants of Galactic Subhalos and Their Impact on Indirect Dark-Matter Searches

Galaxies ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 65 ◽  
Author(s):  
Martin Stref ◽  
Thomas Lacroix ◽  
Julien Lavalle
Keyword(s):  
Dark Matter ◽  
Computer Simulations ◽  
Gamma Rays ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Tidal Disruption ◽  
Large Numbers ◽  
Boost Factor

Dark-matter subhalos, predicted in large numbers in the cold-dark-matter scenario, should have an impact on dark-matter-particle searches. Recent results show that tidal disruption of these objects in computer simulations is overefficient due to numerical artifacts and resolution effects. Accounting for these results, we re-estimated the subhalo abundance in the Milky Way using semianalytical techniques. In particular, we showed that the boost factor for gamma rays and cosmic-ray antiprotons is increased by roughly a factor of two.

scholarly journals Stellar Over-Densities in the Outer Halo of the Milky Way

2010 ◽  
Vol 27 (1) ◽  
pp. 45-55 ◽  
Author(s):  
Stefan C. Keller
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxy ◽  
Local Density ◽  
Spatial Scales ◽  
Sloan Digital Sky Survey ◽  
Tidal Disruption ◽  
Giant Stars ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Model Predictions

AbstractThis study presents a tomographic survey of a subset of the outer halo (10–40 kpc) drawn from the Sloan Digital Sky Survey Data Release 6. Halo substructure on spatial scales of >3 degrees is revealed as an excess in the local density of sub-giant stars. With an appropriate assumption of a model stellar isochrone it is possible for us to then derive distances to the sub-giant population. We describe three new candidate halo substructures; the 160- and 180-degree over-densities (at distances of 17 and 19 kpc respectively and radii of 1.3 and 1.5 kpc respectively) and an extended feature at 28 kpc that covers at least 162 deg2, the Virgo Equatorial Stream. In addition, we recover the Sagittarius dwarf galaxy (Sgr) leading-arm material and the Virgo Over-Density.The derived distances, together with the number of sub-giant stars associated with each substructure, enables us to derive the integrated luminosity for the features. The tenuous, low surface brightness of the features strongly suggests an origin from the tidal disruption of an accreted galaxy or galaxies. Given the dominance of the tidal debris of Sgr in this region of the sky we investigate if our observations can be accommodated by tidal disruption models for Sgr. The clear discordance between observations and model predictions for known Sgr features means it is difficult to tell unambiguously if the new substructures are related to Sgr or not. Radial velocities in the stellar over-densities will be critical in establishing their origins.

scholarly journals Tidal Disruption of Dark Matter Halos around Proto–Globular Clusters

2006 ◽  
Vol 640 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Takayuki R. Saitoh ◽  
Jin Koda ◽  
Takashi Okamoto ◽  
Keiichi Wada ◽  
Asao Habe
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
Dark Matter Halos ◽  
Tidal Disruption

Is There a Fifth-Force? Using Galaxy Mergers to Constrain Dark-Matter Self-Interactions

2017 ◽  
Author(s):  
Maggie McLean
Keyword(s):  
Dark Matter ◽  
Numerical Simulations ◽  
Fundamental Problem ◽  
Interacting Galaxies ◽  
Galaxy Mergers ◽  
Tidal Disruption ◽  
Fifth Force ◽  
Tidal Forces ◽  
Visible Matter ◽  
The Universe

Over ninety percent of the matter in the universe is believed to be “dark matter,” a mysterious form of matter the nature of which is still unknown. Since it cannot be detected directly, dark matter can only be inferred from its effect on visible matter. This leaves a significant gap in our knowledge. Without the ability to measure the influence of dark matter on other dark matter, we could miss a possible fifth fundamental force which mediates dark matter self-interactions. We propose a means of constraining the existence of a “fifth-force” by observing galaxies that are in the process of merging. Using numerical simulations, we examine the effect of including a hypothetical fifth-force on the tidal disruption of visible matter during galaxy mergers. We find distinct differences in the formation and appearance of tidal features produced during these interactions, providing an observable constraint on the strength of any “fifth-force.” The sheer volume of interacting galaxies that can be observed makes tidal forces a valuable tool in studying a fundamental problem that would otherwise pose a great challenge for physicists.

scholarly journals Extracting galaxy merger timescales I: Tracking haloes with WhereWolf and spinning orbits with OrbWeaver

2019 ◽  
Author(s):  
Rhys J J Poulton ◽  
Chris Power ◽  
Aaron S G Robotham ◽  
Pascal J Elahi
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Hierarchical Models ◽  
Dynamical Evolution ◽  
Dark Matter Halo ◽  
Accurate Description ◽  
Mass Ratio ◽  
Tidal Disruption ◽  
Halo Orbits ◽  
Orbital Parameters

Abstract Hierarchical models of structure formation predict that dark matter halo assembly histories are characterised by episodic mergers and interactions with other haloes. An accurate description of this process will provide insights into the dynamical evolution of haloes and the galaxies that reside in them. Using large cosmological N-body simulations, we characterise halo orbits to study the interactions between substructure haloes and their hosts, and how different evolutionary histories map to different classes of orbits. We use two new software tools - WhereWolf, which uses halo group catalogues and merger trees to ensure that haloes are tracked accurately in dense environments, and OrbWeaver, which quantifies each halo’s orbital parameters. We demonstrate how WhereWolf improves the accuracy of halo merger trees, and we use OrbWeaver to quantify orbits of haloes. We assess how well analytical prescriptions for the merger timescale from the literature compare to measured merger timescales from our simulations and find that existing prescriptions perform well, provided the ratio of substructure-to-host mass is not too small. In the limit of small substructure-to-host mass ratio, we find that the prescriptions can overestimate the merger timescales substantially, such that haloes are predicted to survive well beyond the end of the simulation. This work highlights the need for a revised analytical prescription for the merger timescale that more accurately accounts for processes such as catastrophic tidal disruption.

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