A NEXT-GENERATION CAVITY MICROWAVE EXPERIMENT TO SEARCH FOR DARK-MATTER AXIONS

1994 ◽  
Vol 03 (supp01) ◽  
pp. 33-42 ◽  
Author(s):  
K. VAN BIBBER ◽  
W. STÖFFL ◽  
P.L. ANTHONY ◽  
P. SIKIVIE ◽  
N.S. SULLIVAN ◽  
...  
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Joint Venture ◽  
Galactic Halo ◽  
Nuclear Research ◽  
Superconducting Magnet ◽  
Mass Range ◽  
Microwave Cavity ◽  
Experimental Program ◽  
Academy Of Sciences

We propose a large-scale experimental search for dark-matter axions which may constitute an important fraction of our own galactic halo. As shown by Sikivie,1 dark-matter axions may be detected by their stimulated conversion into monochromatic microwave photons in a tunable high-Q cavity inside a strong magnetic field. The principal improvement in power sensitivity over two earlier pilot experiments (×25) derives from the large-volume high field superconducting magnet (the NASA SUMMA coils). The improvement in mass range (1.5 to 12.6 μeV) will result from the use of several microwave cavity arrays, of 2n cavities each, over the course of the experimental program, rather than a single cavity. We are participating in a joint venture with the Institute for Nuclear Research of the Russian Academy of Sciences to do R&D on metalized precision-formed ceramic microwave cavities for the axion search.

scholarly journals Quantifying tidal stream disruption in a simulated Milky Way

2017 ◽  
Vol 470 (1) ◽  
pp. 522-538 ◽  
Author(s):  
Emily Sandford ◽  
Andreas H. W. Küpper ◽  
Kathryn V. Johnston ◽  
Jürg Diemand
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Galactic Halo ◽  
Mass Range ◽  
Galactic Centre ◽  
High Dimensions ◽  
Density Profiles ◽  
Upper Limits ◽  
Tidal Stream ◽  
Tidal Streams

Abstract Simulations of tidal streams show that close encounters with dark matter subhaloes induce density gaps and distortions in on-sky path along the streams. Accordingly, observing disrupted streams in the Galactic halo would substantiate the hypothesis that dark matter substructure exists there, while in contrast, observing collimated streams with smoothly varying density profiles would place strong upper limits on the number density and mass spectrum of subhaloes. Here, we examine several measures of stellar stream ‘disruption' and their power to distinguish between halo potentials with and without substructure and with different global shapes. We create and evolve a population of 1280 streams on a range of orbits in the Via Lactea II simulation of a Milky Way-like halo, replete with a full mass range of Λcold dark matter subhaloes, and compare it to two control stream populations evolved in smooth spherical and smooth triaxial potentials, respectively. We find that the number of gaps observed in a stellar stream is a poor indicator of the halo potential, but that (i) the thinness of the stream on-sky, (ii) the symmetry of the leading and trailing tails and (iii) the deviation of the tails from a low-order polynomial path on-sky (‘path regularity') distinguish between the three potentials more effectively. We furthermore find that globular cluster streams on low-eccentricity orbits far from the galactic centre (apocentric radius ∼30–80 kpc) are most powerful in distinguishing between the three potentials. If they exist, such streams will shortly be discoverable and mapped in high dimensions with near-future photometric and spectroscopic surveys.

scholarly journals Cosmological baryon transfer in the simba simulations

2019 ◽  
Vol 491 (4) ◽  
pp. 6102-6119 ◽  
Author(s):  
Josh Borrow ◽  
Daniel Anglés-Alcázar ◽  
Romeel Davé
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Initial Conditions ◽  
Mass Range ◽  
Gas Content ◽  
Final State ◽  
Cosmological Simulations ◽  
Baryon Transfer ◽  
Matter Component

ABSTRACT We present a framework for characterizing the large-scale movement of baryons relative to dark matter in cosmological simulations, requiring only the initial conditions and final state of the simulation. This is performed using the spread metric that quantifies the distance in the final conditions between initially neighbouring particles, and by analysing the baryonic content of final haloes relative to that of the initial Lagrangian regions (LRs) defined by their dark matter component. Applying this framework to the simba cosmological simulations, we show that 40 per cent (10 per cent) of cosmological baryons have moved $\gt 1\, h^{-1}\, {\rm Mpc}{}$ ($3\, h^{-1}\, {\rm Mpc}{}$) by z = 0, primarily due to entrainment of gas by jets powered by an active galactic nucleus, with baryons moving up to $12\, h^{-1}\, {\rm Mpc}{}$ away in extreme cases. Baryons decouple from the dynamics of the dark matter component due to hydrodynamic forces, radiative cooling, and feedback processes. As a result, only 60 per cent of the gas content in a given halo at z = 0 originates from its LR, roughly independent of halo mass. A typical halo in the mass range Mvir = 1012–1013 M⊙ only retains 20 per cent of the gas originally contained in its LR. We show that up to 20 per cent of the gas content in a typical Milky Way-mass halo may originate in the region defined by the dark matter of another halo. This inter-Lagrangian baryon transfer may have important implications for the origin of gas and metals in the circumgalactic medium of galaxies, as well as for semi-analytic models of galaxy formation and ‘zoom-in’ simulations.

Large-scale microwave cavity search for dark-matter axions

2001 ◽  
Vol 64 (9) ◽  
Author(s):  
S. Asztalos ◽  
E. Daw ◽  
H. Peng ◽  
L. J Rosenberg ◽  
C. Hagmann ◽  
...  
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Microwave Cavity

scholarly journals The electron plus positron spectrum from annihilation of Kaluza–Klein dark matter in the Galaxy

2017 ◽  
Vol 26 (09) ◽  
pp. 1750095 ◽  
Author(s):  
Satoshi Tsuchida ◽  
Masaki Mori
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Galactic Halo ◽  
Mass Range ◽  
Decay Modes ◽  
Positron Fraction ◽  
Electrons And Positrons ◽  
The Galaxy ◽  
Positron Spectrum ◽  
Kaluza Klein

The lightest Kaluza–Klein particle (LKP), which appears in the theory of universal extra dimensions (UED), is one of the good candidates for cold dark matter (CDM). When LKP pairs annihilate around the center of the Galaxy where CDM is concentrated, there are some modes which produce electrons and positrons as final products, and we categorize them into two components. One of them is the “line” component, which directly annihilates into electron–positron pair. Another one is the “continuum” component, which consists of secondarily produced electrons and positrons via some decay modes. Before reaching Earth, directions of electrons and positrons are randomized by the Galactic magnetic field, and their energies are reduced by energy loss mechanisms. We assume the LKP is in the mass range from 300[Formula: see text]GeV to 1500[Formula: see text]GeV. We calculate the electron plus positron spectrum after propagation in the Galactic halo to Earth, and we analyze the resulting spectrum and positron fraction. We also point out that the energy dependence of observed positron fraction is well reproduced by the mixture of “line” and “continuum” components. We can fit the electron plus positron spectrum and the positron fraction by assuming appropriate boost factors describing dark matter concentration in the Galactic halo. However, it is difficult to explain both the electron plus positron spectrum and the positron fraction by a single boost factor if we take account of observational data obtained by AMS-02 only.

scholarly journals Baryonic effects on the detectability of annihilation radiation from dark matter subhaloes around the Milky Way

2020 ◽  
Author(s):  
Robert J J Grand ◽  
Simon D M White
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Milky Way ◽  
Galactic Halo ◽  
Mass Range ◽  
Annihilation Radiation ◽  
Dark Matter Annihilation ◽  
Halo Structure ◽  
Robust Detection ◽  
Halo Masses

Abstract We use six, high-resolution ΛCDM simulations of galaxy formation to study how emission from dark matter annihilation is affected by baryonic processes. These simulations produce isolated, disc-dominated galaxies with structure, stellar populations, and stellar and halo masses comparable to those of the Milky Way. They resolve dark matter structures with mass above ∼106  $\rm M_{\odot }$ and are each available in both full-physics and dark-matter-only versions. In the full-physics case, formation of the stellar galaxy enhances annihilation radiation from the dominant smooth component of the galactic halo by a factor of three, and its central concentration increases substantially. In contrast, subhalo fluxes are reduced by almost an order of magnitude, partly because of changes in internal structure, partly because of increased tidal effects; they drop relative to the flux from the smooth halo by 1.5 orders of magnitude. The expected flux from the brightest Milky Way subhalo is four orders of magnitude below that from the smooth halo, making it very unlikely that any subhalo will be detected before robust detection of the inner Galaxy. We use recent simulations of halo structure across the full ΛCDM mass range to extrapolate to the smallest (Earth-mass) subhaloes, concluding, in contrast to earlier work, that the total annihilation flux from Milky Way subhaloes will be less than that from the smooth halo, as viewed both from the Sun and by a distant observer. Fermi-LAT may marginally resolve annihilation radiation from the very brightest subhaloes, which, typically, will contain stars.

scholarly journals Future directions in the microwave cavity search for dark matter axions

2014 ◽  
Vol 29 (19) ◽  
pp. 1443004 ◽  
Author(s):  
T. M. Shokair ◽  
J. Root ◽  
K. A. Van Bibber ◽  
B. Brubaker ◽  
Y. V. Gurevich ◽  
...  
Keyword(s):  
Dark Matter ◽  
Mass Range ◽  
Dark Matter Halo ◽  
Microwave Cavity ◽  
Strong Interactions ◽  
Dark Matter Candidate ◽  
Test Bed ◽  
Technological Advances ◽  
Pseudoscalar Particle ◽  
Low Mass

The axion is a light pseudoscalar particle which suppresses CP-violating effects in strong interactions and also happens to be an excellent dark matter candidate. Axions constituting the dark matter halo of our galaxy may be detected by their resonant conversion to photons in a microwave cavity permeated by a magnetic field. The current generation of the microwave cavity experiment has demonstrated sensitivity to plausible axion models, and upgrades in progress should achieve the sensitivity required for a definitive search, at least for low mass axions. However, a comprehensive strategy for scanning the entire mass range, from 1–1000 μeV, will require significant technological advances to maintain the needed sensitivity at higher frequencies. Such advances could include sub-quantum-limited amplifiers based on squeezed vacuum states, bolometers, and/or superconducting microwave cavities. The Axion Dark Matter eXperiment at High Frequencies (ADMX-HF) represents both a pathfinder for first data in the 20–100 μeV range (~5–25 GHz), and an innovation test-bed for these concepts.

scholarly journals Dark Matter Haloes and Subhaloes

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 81 ◽  
Author(s):  
Jesús Zavala ◽  
Carlos S. Frenk
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Mass Range ◽  
Temperature Structure ◽  
N Body Problem ◽  
Central Regions ◽  
Low Mass

The development of methods and algorithms to solve the N-body problem for classical, collisionless, non-relativistic particles has made it possible to follow the growth and evolution of cosmic dark matter structures over most of the universe’s history. In the best-studied case—the cold dark matter or CDM model—the dark matter is assumed to consist of elementary particles that had negligible thermal velocities at early times. Progress over the past three decades has led to a nearly complete description of the assembly, structure, and spatial distribution of dark matter haloes, and their substructure in this model, over almost the entire mass range of astronomical objects. On scales of galaxies and above, predictions from this standard CDM model have been shown to provide a remarkably good match to a wide variety of astronomical data over a large range of epochs, from the temperature structure of the cosmic background radiation to the large-scale distribution of galaxies. The frontier in this field has shifted to the relatively unexplored subgalactic scales, the domain of the central regions of massive haloes, and that of low-mass haloes and subhaloes, where potentially fundamental questions remain. Answering them may require: (i) the effect of known but uncertain baryonic processes (involving gas and stars), and/or (ii) alternative models with new dark matter physics. Here we present a review of the field, focusing on our current understanding of dark matter structure from N-body simulations and on the challenges ahead.

DARK MATTER ANNIHILATION IN THE LATE UNIVERSE

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1643-1648
Author(s):  
NICOLE F. BELL
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Galactic Halo ◽  
Atmospheric Neutrino ◽  
Mass Range ◽  
Annihilation Cross Section ◽  
Dark Matter Annihilation ◽  
Unitarity Bound ◽  
Dark Matter Mass ◽  
Positron Flux

We examine dark matter annihilation in the Universe today. We first discuss the suggestion that the Galactic positron flux, which is difficult to account for with astrophysical sources, is produced by the annihilation of dark matter in the Galactic halo. We show that the positrons produced would necessarily be accompanied by a flux of gamma rays which exceed observational constraints, unless the dark matter mass is very low. We shall also derive a very general bond on the dark matter annihilation cross section. By considering annihilation into all Standard Model particles, we show that the least detectable final states, namely neutrinos, define an upper bound on the total annihilation cross section. Calculating the cosmic diffuse neutrino signal, and comparing it to the measured terrestrial atmospheric neutrino background, we derive a robust limit that is much stronger than the unitarity bound in the most interesting mass range. We conclude that dark matter self-annihilation rates cannot be large enough to have a significant effect on the density profiles of dark matter halos.

scholarly journals A Search for Dark Matter in the Halos of Lensing Galaxies using VLBI

1996 ◽  
Vol 173 ◽  
pp. 189-190
Author(s):  
M.A. Garrett ◽  
S. Nair ◽  
R.W. Porcas ◽  
A.R. Patnaik
Keyword(s):  
Dark Matter ◽  
Galactic Halo ◽  
Mass Range ◽  
Lower Mass ◽  
Solar Mass ◽  
Dwarf Stars ◽  
Main Mass ◽  
Baryonic Dark Matter

Baryonic Dark Matter (BDM) candidates are segregated into two main mass ranges: (i) sub-solar mass dwarf stars (MACHOS) and (ii) ∼ 104–106M⊙ Very Massive Objects (VMOs). The lower mass range has been the target of the various micro-lensing programs but the first, tentative conclusions (see Stubbs et al. these proceedings) seem to suggest that MACHOs are unlikely to provide the bulk of the dark matter in the galactic halo. Meanwhile the upper mass range (104–106M⊙) remains largely unexplored. However, Wambsganss & Paczynski 1992 (hereafter WP92), have shown that this mass range is perfectly tuned to a straightforward and direct test: gravitational milli-lensing of macro-lensed images (Fig 1).

scholarly journals LARGE SCALE STRUCTURE BY GLOBAL MONOPOLES AND COLD DARK MATTER

1992 ◽  
Vol 07 (10) ◽  
pp. 903-910 ◽  
Author(s):  
LEANDROS PERIVOLAROPOULOS
Keyword(s):  
Dark Matter ◽  
Cosmological Model ◽  
Gravitational Wave ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Mass Range ◽  
Large Scale Structure ◽  
Mass Function ◽  
Global Monopoles ◽  
Good Agreement

A cosmological model in which the primordial perturbations are provided by global monopoles and in which the dark matter is cold has several interesting features. The model is normalized by choosing its single parameter within the bounds obtained from gravitational wave constraints and by demanding coherent velocity flows of about 600 km/sec on scales of 50h-1 Mpc . Using this normalization, the model predicts the existence of dominant structures with mass 2×1016M⊙ on a scale 35h-1 Mpc , i.e., larger than the horizon at t ep . The magnitude of the predicted mass function in the galactic mass range is in good agreement with the observed Schechter function.

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