TY  - JOUR
A1  - Gong, Chen Chris
A1  - Libeskind, Noam I.
A1  - Tempel, Elmo
A1  - Guo, Quan
A1  - Gottloeber, Stefan
A1  - Yepes, Gustavo
A1  - Wang, Peng
A1  - Sorce, Jenny
A1  - Pawlowski, Marcel
T1  - The origin of lopsided satellite galaxy distribution in galaxy pairs
JF  - Monthly notices of the Royal Astronomical Society
N2  - It is well known that satellite galaxies are not isotropically distributed among their host galaxies as suggested by most interpretations of the Λ cold dark matter (ΛCDM) model. One type of anisotropy recently detected in the Sloan Digital Sky Survey (and seen when examining the distribution of satellites in the Local Group and in the Centaurus group) is a tendency to be so-called lopsided. Namely, in pairs of galaxies (like Andromeda and the Milky Way) the satellites are more likely to inhabit the region in between the pair, rather than on opposing sides. Although recent studies found a similar set-up when comparing pairs of galaxies in ΛCDM simulations indicating that such a set-up is not inconsistent with ΛCDM, the origin has yet to be explained. Here we examine the origin of such lopsided set-ups by first identifying such distributions in pairs of galaxies in numerical cosmological simulations, and then tracking back the orbital trajectories of satellites (which at z = 0 display the effect). We report two main results: first, the lopsided distribution was stronger in the past and weakens towards z = 0. Secondly, the weakening of the signal is due to the interaction of satellite galaxies with the pair. Finally, we show that the z = 0 signal is driven primarily by satellites that are on first approach, who have yet to experience a ‘flyby’. This suggests that the signal seen in the observations is also dominated by dynamically young accretion events.
KW  - galaxies: evolution
KW  - galaxies: formation
KW  - galaxy: kinematics and dynamics
KW  - Local Group
KW  - dark matter
KW  - cosmology: theory
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/stz1917
SN  - 0035-8711
SN  - 1365-2966
VL  - 488
IS  - 3
SP  - 3100
EP  - 3108
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Despali, Giulia
A1  - Sparre, Martin
A1  - Vegetti, Simona
A1  - Vogelsberger, Mark
A1  - Zavala, Jesús
A1  - Marinacci, Federico
T1  - The interplay of self-interacting dark matter and baryons in shaping the halo evolution
JF  - Monthly notices of the Royal Astronomical Society
N2  - We use high-resolution hydrodynamical simulation to test the difference of halo properties in cold dark matter (CDM) and a self-interacting dark matter (SIDM) scenario with a constant cross-section of sigma(T)/m(x) = 1 cm(2) g(-1). We find that the interplay between dark matter self-interaction and baryonic physics induces a complex evolution of the halo properties, which depends on the halo mass and morphological type, as well as on the halo mass accretion history. While high-mass haloes, selected as analogues of early-type galaxies, show cored profiles in the SIDM run, systems of intermediate mass and with a significant disc component can develop a profile that is similar or cuspier than in CDM. The final properties of SIDM haloes - measured at z = 0.2 - correlate with the halo concentration and formation time, suggesting that the differences between different systems are due to the fact that we are observing the impact of self-interaction. We also search for signatures of SIDM in the lensing signal of the main haloes and find hints of potential differences in the distribution of Einstein radii, which suggests that future wide-field survey might be able to distinguish between CDM and SIDM models on this basis. Finally, we find that the subhalo abundances are not altered in the adopted SIDM model with respect to CDM.
KW  - gravitational lensing: strong
KW  - methods: numerical
KW  - galaxies: haloes
KW  - dark matter
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/stz273
SN  - 0035-8711
SN  - 1365-2966
VL  - 484
IS  - 4
SP  - 4563
EP  - 4573
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Baushev, Anton N.
T1  - Relaxation of dark matter halos: how to match observational data?
JF  - Astronomy and astrophysics : an international weekly journal
N2  - We show that moderate energy relaxation in the formation of dark matter halos invariably leads to profiles that match those observed in the central regions of galaxies. The density profile of the central region is universal and insensitive to either the seed perturbation shape or the details of the relaxation process. The profile has a central core; the multiplication of the central density by the core radius is almost independent of the halo mass, in accordance with observations. In the core area the density distribution behaves as an Einasto profile with low index (n similar to 0.5); it has an extensive region with rho proportional to r(-2) at larger distances. This is exactly the shape that observations suggest for the central region of galaxies. On the other hand, this shape does not fit the galaxy cluster profiles. A possible explanation of this fact is that the relaxation is violent in the case of galaxy clusters; however, it is not violent enough when galaxies or smaller dark matter structures are considered. We discuss the reasons for this.
KW  - dark matter
KW  - Galaxy: structure
KW  - Galaxy: formation
KW  - astroparticle physics
KW  - methods: analytical
Y1  - 2014
U6  - https://doi.org/10.1051/0004-6361/201322730
SN  - 0004-6361
SN  - 1432-0746
VL  - 569
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Baushev, Anton N.
T1  - Principal properties of the velocity distribution of dark matter particles on the outskirts of the Solar system
JF  - Monthly notices of the Royal Astronomical Society
N2  - The velocity distribution of the dark matter particles on the outskirts of the Solar system remains unclear. We suggest to determine it using experimentally found properties of the oldest halo objects. Indeed, the oldest halo stars and globular clusters form a collisionless system, as well as dark matter particles do, and they evolved in the same gravitational field. If we accept this analogy, we can show that the velocity distribution of the dark matter particles should be highly anisotropic and have a sharp maximum near upsilon similar to 500 km s(-1). The distribution is totally different from the Maxwell one.
 We analyse the influence of the distribution function on the results of dark matter detection experiments. It is found that the direct detection signal should differ noticeably from the one calculated from the Maxwell distribution with <upsilon > similar or equal to 220 km s(-1), which is conventional for direct detection experiments (the ratio depends on the detector properties and typically falls within the range between 6 and 0.2). Moreover, the sharp distinction from the Maxwell distribution can be very essential to the observations of dark matter annihilation.
KW  - elementary particles
KW  - methods: analytical
KW  - dark matter
Y1  - 2011
U6  - https://doi.org/10.1111/j.1745-3933.2011.01125.x
SN  - 0035-8711
VL  - 417
IS  - 1
SP  - L83
EP  - L87
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Emma, Mattia
A1  - Schianchi, Federico
A1  - Pannarale, Francesco
A1  - Sagun, Violetta
A1  - Dietrich, Tim
T1  - Numerical simulations of dark matter admixed neutron star binaries
JF  - Particles
N2  - Multi-messenger observations of compact binary mergers provide a new way to constrain the nature of dark matter that may accumulate in and around neutron stars. In this article, we extend the infrastructure of our numerical-relativity code BAM to enable the simulation of neutron stars that contain an additional mirror dark matter component. We perform single star tests to verify our code and the first binary neutron star simulations of this kind. We find that the presence of dark matter reduces the lifetime of the merger remnant and favors a prompt collapse to a black hole. Furthermore, we find differences in the merger time for systems with the same total mass and mass ratio, but different amounts of dark matter. Finally, we find that electromagnetic signals produced by the merger of binary neutron stars admixed with dark matter are very unlikely to be as bright as their dark matter-free counterparts. Given the increased sensitivity of multi-messenger facilities, our analysis gives a new perspective on how to probe the presence of dark matter.
KW  - numerical relativity
KW  - dark matter
KW  - neutron stars
KW  - equation of state;
KW  - gravitational-wave astronomy
KW  - multi-messenger astrophysics
Y1  - 2022
U6  - https://doi.org/10.3390/particles5030024
SN  - 2571-712X
VL  - 5
IS  - 3
SP  - 273
EP  - 286
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Baushev, Anton N.
T1  - Interaction of clumpy dark matter with interstellar medium in astrophysical systems
JF  - Monthly notices of the Royal Astronomical Society
N2  - Contemporary cosmological conceptions suggest that the dark matter in haloes of galaxies and galaxy clusters has most likely a clumpy structure. If a stream of gas penetrates through it, a small-scale gravitational field created by the clumps disturbs the flow resulting in momentum exchange between the stream and the dark matter. In this article, we perform an analysis of this effect, based on the hierarchical halo model of the dark matter structure and Navarro-Frenk-White density profiles. We consider the clumps of various masses, from the smallest up to the highest ones M = 10(9) M circle dot. It has been found that in any event the effect grows with the mass of the clump: not only the drag force F acting on the clump but also its acceleration w = F/M increases.
 We discuss various astrophysical systems. The mechanism proved to be ineffective in the case of galaxy or galaxy cluster collisions. On the other hand, it played an important role during the process of galaxy formation. As a result, the dark matter should have formed a more compact, oblate and faster rotating substructure in the halo of our Galaxy. We have shown that this thick disc should be more clumpy than the halo. This fact is very important for the indirect detection experiments since it is the clumps that give the main contribution to the annihilation signal. Our calculations show that the mechanism of momentum exchange between the dark and baryon matter is ineffective on the outskirts of the galactic halo. It means that the clumps from there were not transported to the thick disc, and this region should be more clumpy than the halo on the average.
KW  - elementary particles
KW  - cosmology: theory
KW  - dark matter
Y1  - 2012
U6  - https://doi.org/10.1111/j.1365-2966.2011.20067.x
SN  - 0035-8711
VL  - 420
IS  - 1
SP  - 590
EP  - 595
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Baushev, Anton N.
T1  - Galaxy halo formation in the absence of violent relaxation and a universal density profile of the halo center
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - While N-body simulations testify to a cuspy profile of the central region of dark matter halos, observations favor a shallow, cored density profile of the central region of at least some spiral galaxies and dwarf spheroidals. We show that a central profile, very close to the observed one, inevitably forms in the center of dark matter halos if we make a supposition about a moderate energy relaxation of the system during the halo formation. If we assume the energy exchange between dark matter particles during the halo collapse is not too intensive, the profile is universal: it depends almost not at all on the properties of the initial perturbation and is very akin, but not identical, to the Einasto profile with a small Einasto index n similar to 0.5. We estimate the size of the "central core" of the distribution, i.e., the extent of the very central region with a respectively gentle profile, and show that the cusp formation is unlikely, even if the dark matter is cold. The obtained profile is in good agreement with observational data for at least some types of galaxies but clearly disagrees with N-body simulations.
KW  - astroparticle physics
KW  - dark matter
KW  - elementary particles
KW  - large-scale structure of universe
Y1  - 2014
U6  - https://doi.org/10.1088/0004-637X/786/1/65
SN  - 0004-637X
SN  - 1538-4357
VL  - 786
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Baushev, Anton N.
T1  - Extragalactic dark matter and direct detection experiments
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - Recent astronomical data strongly suggest that a significant part of the dark matter content of the Local Group and Virgo Supercluster is not incorporated into the galaxy halos and forms diffuse components of these galaxy clusters. A portion of the particles from these components may penetrate the Milky Way and make an extragalactic contribution to the total dark matter containment of our Galaxy. We find that the particles of the diffuse component of the Local Group are apt to contribute similar to 12% to the total dark matter density near Earth. The particles of the extragalactic dark matter stand out because of their high speed (similar to 600 km s(-1)), i.e., they are much faster than the galactic dark matter. In addition, their speed distribution is very narrow (similar to 20 km s(-1)). The particles have an isotropic velocity distribution (perhaps, in contrast to the galactic dark matter). The extragalactic dark matter should provide a significant contribution to the direct detection signal. If the detector is sensitive only to the fast particles (v > 450 km s(-1)), then the signal may even dominate. The density of other possible types of the extragalactic dark matter (for instance, of the diffuse component of the Virgo Supercluster) should be relatively small and comparable with the average dark matter density of the universe. However, these particles can generate anomaly high-energy collisions in direct dark matter detectors.
KW  - astroparticle physics
KW  - dark matter
KW  - elementary particles
KW  - Local Group
Y1  - 2013
U6  - https://doi.org/10.1088/0004-637X/771/2/117
SN  - 0004-637X
VL  - 771
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Arlen, T.
A1  - Aune, T.
A1  - Beilicke, M.
A1  - Benbow, W.
A1  - Bouvier, A.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cannon, A.
A1  - Cesarini, A.
A1  - Ciupik, L.
A1  - Collins-Hughes, E.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dickherber, R.
A1  - Dumm, J.
A1  - Falcone, A.
A1  - Federici, S.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Finnegan, G.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Galante, N.
A1  - Gall, D.
A1  - Godambe, S.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Gyuk, G.
A1  - Holder, J.
A1  - Huan, H.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Imran, A.
A1  - Kaaret, P.
A1  - Karlsson, N.
A1  - Kertzman, M.
A1  - Khassen, Y.
A1  - Kieda, D.
A1  - Krawczynski, H.
A1  - Krennrich, F.
A1  - Lee, K.
A1  - Madhavan, A. S.
A1  - Maier, G.
A1  - Majumdar, P.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nelson, T.
A1  - de Bhroithe, A. O'Faolain
A1  - Ong, R. A.
A1  - Orr, M.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Perkins, J. S.
A1  - Pohl, Martin
A1  - Prokoph, H.
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Roache, E.
A1  - Ruppel, J.
A1  - Saxon, D. B.
A1  - Schroedter, M.
A1  - Sembroski, G. H.
A1  - Skole, C.
A1  - Smith, A. W.
A1  - Telezhinsky, Igor O.
A1  - Tesic, G.
A1  - Theiling, M.
A1  - Thibadeau, S.
A1  - Tsurusaki, K.
A1  - Varlotta, A.
A1  - Vivier, M.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weinstein, A.
A1  - Welsing, R.
A1  - Williams, D. A.
A1  - Zitzer, B.
A1  - Pfrommer, C.
A1  - Pinzke, A.
T1  - Constraints on cosmic rays, magnetic fields, and dark matter fromgamma-ray observations of the coma cluster of galaxies with veritas and fermi
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E > 100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5) x 10(-8) photonsm(-2) s(-1) (VERITAS, >220 GeV) and similar to 2 x 10(-6) photonsm(-2) s(-1) (Fermi, 1-3GeV), respectively. We use the gamma-ray upper limits to constrain cosmic rays (CRs) and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be < 16% from VERITAS data and <1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be <50%. Alternatively, this may argue for non-negligible CR transport processes such as CR streaming and diffusion into the outer cluster regions. Assuming that the radio-emitting electrons of the Coma halo result from hadronic CR interactions, the observations imply a lower limit on the central magnetic field in Coma of similar to(2-5.5) mu G, depending on the radial magnetic field profile and on the gamma-ray spectral index. Since these values are below those inferred by Faraday rotation measurements in Coma (for most of the parameter space), this renders the hadronic model a very plausible explanation of the Coma radio halo. Finally, since galaxy clusters are dark matter (DM) dominated, the VERITAS upper limits have been used to place constraints on the thermally averaged product of the total self-annihilation cross section and the relative velocity of the DM particles, <sigma nu >.
KW  - cosmic rays
KW  - dark matter
KW  - galaxies: clusters: general
KW  - galaxies: clusters: individual (Coma (ACO 1656))
KW  - gamma rays: galaxies: clusters
KW  - magnetic fields
Y1  - 2012
U6  - https://doi.org/10.1088/0004-637X/757/2/123
SN  - 0004-637X
VL  - 757
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -