scholarly journals Direct detection of atomic dark matter in white dwarfs

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
David Curtin ◽  
Jack Setford
Keyword(s):  
Dark Matter ◽  
Energy Loss ◽  
Cooling Rate ◽  
White Dwarf ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Direct Detection ◽  
Matter Density ◽  
Mixing Parameter ◽  
First Time

Abstract Dark matter could have a dissipative asymmetric subcomponent in the form of atomic dark matter (aDM). This arises in many scenarios of dark complexity, and is a prediction of neutral naturalness, such as the Mirror Twin Higgs model. We show for the first time how White Dwarf cooling provides strong bounds on aDM. In the presence of a small kinetic mixing between the dark and SM photon, stars are expected to accumulate atomic dark matter in their cores, which then radiates away energy in the form of dark photons. In the case of white dwarfs, this energy loss can have a detectable impact on their cooling rate. We use measurements of the white dwarf luminosity function to tightly constrain the kinetic mixing parameter between the dark and visible photons, for DM masses in the range 10−5–105 GeV, down to values of ϵ ∼ 10−12. Using this method we can constrain scenarios in which aDM constitutes fractions as small as 10−3 of the total dark matter density. Our methods are highly complementary to other methods of probing aDM, especially in scenarios where the aDM is arranged in a dark disk, which can make direct detection extremely difficult but actually slightly enhances our cooling constraints.

scholarly journals The White Dwarf Luminosity Function and the Phase Diagram of the Carbon-Oxygen Dense Plasma

1988 ◽  
Vol 108 ◽  
pp. 88-89
Author(s):  
E. Garcìa-Berro ◽  
M. Hernanz ◽  
R. Mochkovitch ◽  
J. Isern
Keyword(s):  
Phase Diagram ◽  
Cooling Rate ◽  
White Dwarf ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Dense Plasma ◽  
Solid Phase ◽  
Complete Separation ◽  
Gravitational Energy ◽  
Complete Miscibility

AbstractWe show that the theoretical white dwarf luminosity function depends very much on the assumed phase diagram for the carbon-oxygen dense plasma. Since it is still very uncertain, we compare the two possible extreme cases of complete miscibility and complete separation of carbon and oxygen in solid phase. In the latter case we find that the paucity of low luminosity — log(L/L⊙) ≤ −4.5 — white dwarfs can be explained by the formation of an oxygen core, which releases a large amount of gravitational energy and slows down the cooling rate.

scholarly journals The Z5 model of two-component dark matter

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Geneviève Bélanger ◽  
Alexander Pukhov ◽  
Carlos E. Yaguna ◽  
Óscar Zapata
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Direct Detection ◽  
Scalar Fields ◽  
Matter Density ◽  
Scalar Model ◽  
Complex Scalar ◽  
Two Component ◽  
Model Features ◽  
First Time

Abstract Scenarios for multi-component scalar dark matter based on a single ZN (N ≥ 4) symmetry are simple and well-motivated. In this paper we investigate, for the first time, the phenomenology of the Z5 model for two-component dark matter. This model, which can be seen as an extension of the well-known singlet scalar model, features two complex scalar fields — the dark matter particles — that are Standard Model singlets but have different charges under a Z5 symmetry. The interactions allowed by the Z5 give rise to novel processes between the dark matter particles that affect their relic densities and their detection prospects, which we study in detail. The key parameters of the model are identified and its viable regions are characterized by means of random scans. We show that, unlike the singlet scalar model, dark matter masses below the TeV are still compatible with present data. Even though the dark matter density turns out to be dominated by the lighter component, we find that current and future direct detection experiments may be sensitive to signals from both dark matter particles.

scholarly journals White Dwarf Seismology at the Université de Montréal

1993 ◽  
Vol 139 ◽  
pp. 120-120
Author(s):  
G. Fontaine ◽  
P. Brassard ◽  
P. Bergeron ◽  
F. Wesemael
Keyword(s):  
Specific Heat ◽  
Cooling Rate ◽  
Internal Structure ◽  
White Dwarf ◽  
White Dwarfs ◽  
Period Change ◽  
Core Material ◽  
The Core ◽  
Core Composition ◽  
Chemical Stratification

Over the last several years, we have developed a comprehensive program aimed at better understanding the properties of pulsating DA white dwarfs (or ZZ Ceti stars). These stars are nonradial pulsators of the g-type, and their study can lead to inferences about their internal structure. For instance, the period spectrum of a white dwarf is most sensitive to its vertical chemical stratification, and one of the major goals of white dwarf seismology is to determine the thickness of the hydrogen layer that sits on top of a star. This can be done, in principle, by comparing in detail theoretical period spectra with the periods of the observed excited modes. Likewise, because the cooling rate of a white dwarf is very sensitive to the specific heat of its core material (and hence to its composition), it is possible to infer the core composition through measurements and interpretations of rates of period change in a pulsator.

scholarly journals Extending the White Dwarf Sequence: Plans and Prospects

1978 ◽  
Vol 80 ◽  
pp. 437-440
Author(s):  
James Liebert
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Selection Effects ◽  
Number Density ◽  
Low Velocity ◽  
Luminosity Functions ◽  
Current Sample ◽  
The Many

The recent discovery that the parallax star LP701-29 is a white dwarf has firmly extended the degenerate sequence below MV= +16m(Dahnet al. 1978). As the search for white dwarfs extends to cooler and fainter stars, however, it becomes particularly important to develop a plan for selecting candidates among the many thousands of red proper motion stars. We begin by assessing the completeness of the known sample within 10 parsecs in the northern two thirds of the sky. Some color-dependent selection effects must be evaluated, however, since these may preferentially inhibit the discovery of cooler stars. A correction factor for the missing low velocity white dwarfs is estimated. Then, Green's(1977) recent determination of the number density of blue degenerates is used to normalize various theoretical luminosity functions, the benchmarks against which the current sample out to 10 pc can be compared. It is concluded that the sample may be approaching completeness in the northern sky for white dwarfs with tangential velocities (vT) ≥ 40 km/sec (μ ≥ 1″.0/yr.) and Mbol< +15m. The implied luminosity function is thus consistent with that found by Sion and Liebert (1977). Below Mbol= +15mthe different theoretical functions predict substantially different numbers.

scholarly journals Diffusion and Metal Abundances in Hot White Dwarfs Gerard Vauclair

1989 ◽  
Vol 114 ◽  
pp. 176-187 ◽  
Author(s):  
Gérard Vauclair
Keyword(s):  
Time Scales ◽  
White Dwarf ◽  
White Dwarfs ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Metal Abundances ◽  
Cool White Dwarfs ◽  
First Time ◽  
Radiative Acceleration

While the efficiency of gravitational settling to produce chemically pure atmospheres in white dwarf stars was outlined for the first time 30 years ago (Schatzman 1958), the competing role of the radiation flux in the hot white dwarfs was considered only 10 years ago (Fontaine and Michaud 1979; Vauclair, Vauclair and Greenstein 1979). At that time, there was more motivation to understand how metals could reappear in the long lived cool non DA white dwarfs, where diffusion time scales are shorter by orders of magnitude than evolutionary time scales. Various processes were invoked to help restore some metal content in the white dwarf atmospheres: convection mixing and dredge up, accretion of interstellar matter. In cool white dwarfs, the radiative acceleration is negligeable in the diffusion process; this is not the case at the hot end of the sequence where radiation may balance gravity. The short lived hot white dwarfs just started to become exciting with the contemporary discoveries that i) some show metallic lines in their spectra, both hydrogen rich and hydrogen poor; ii) some of these are pulsating. In the following years, the number of hot white dwarfs revealing trace abundance of metals has increased, mainly owing to IUE observations.

scholarly journals Mass Distribution and Luminosity Function of White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 1-14 ◽  
Author(s):  
Volker Weidemann ◽  
Jie W. Yuan
Keyword(s):  
Mass Loss ◽  
Mass Distribution ◽  
Stellar Evolution ◽  
White Dwarf ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Present Situation ◽  
Single Well ◽  
Mass Dispersion

Ever since Graham’s Strömgren photometry (1972) demonstrated the existence of a single well defined cooling sequence of DA white dwarfs the question of the mass dispersion (or the width of the number-mass distribution) has been in the foreground of my studies (Weidemann, 1970, 1977).Indeed it turned out that the shape of the white dwarf mass distribution provides strong constraints on the theory of stellar evolution with mass loss, a fact which will be demonstrated again in the following lecture. It therefore seems worthwhile to dwell in some detail on the methods of its determination. For the benefit of the non-specialists I shall first present some of the historical results and then continue to discuss the present situation.

scholarly journals Collider constraints on dark mediators

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Hanna Mies ◽  
Christiane Scherb ◽  
Pedro Schwaller
Keyword(s):  
Dark Matter ◽  
Parameter Space ◽  
First Generation ◽  
Direct Detection ◽  
Full Range ◽  
Dark Matter Candidate ◽  
Dark Sector ◽  
Missing Energy ◽  
First Time

Abstract We explore the constraints current collider searches place on a QCD-like dark sector. A combination of multi-jet, multi-jet plus missing energy and emerging jets searches is used to derive constraints on the mediator mass across the full range of the dark meson lifetimes for the first time.The dark sector inherits a flavour structure from the coupling between the dark quarks and the SM quarks through the mediator. When this is taken into account, the differently flavoured dark pions become distinguishable through their lifetime. We show that also in these cases the above mentioned searches remain sensitive, and we obtain limits on the mediator mass also for the flavoured scenario.We then contrast the constraints from collider searches with direct detection bounds on the dark matter candidate itself in both the flavoured and unflavoured scenario. Using a simple prescription it becomes possible to display all constraints in the dark matter and mediator mass plane. Constraints from direct detection tend to be stronger than the collider constraints, unless the coupling to the first generation quarks is suppressed, in which case the collider searches place the most stringent limits on the parameter space.

scholarly journals Dark matter, fine-tuning and (g-2)_{\mu} in the pMSSM

2021 ◽  
Vol 11 (3) ◽  
Author(s):  
Melissa van Beekveld ◽  
Wim Beenakker ◽  
Marrit Schutten ◽  
Jeremy De Wit
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Cross Section ◽  
Direct Detection ◽  
Fine Tuning ◽  
Dark Matter Relic Density ◽  
Depth Analysis ◽  
Relic Density ◽  
The Right ◽  
First Time

In this paper we perform for the first time an in-depth analysis of the spectra in the phenomenological supersymmetric Standard Model that simultaneously offer an explanation for the (g-2)_{\mu}(g−2)μ discrepancy \Delta a_{\mu}Δaμ, result in the right dark-matter relic density \Omega_{DM} h^2ΩDMh2 and are minimally fine-tuned. The resulting spectra may be obtained from [1]. To discuss the experimental exclusion potential for our models, we analyse the resulting LHC phenomenology as well as the sensitivity of dark-matter direct detection experiments to these spectra. We find that the latter type of experiments with sensitivity to the spin-dependent dark-matter–nucleon scattering cross section \sigma_{SD,p}σSD,p will probe all of our found solutions.

scholarly journals Direct detection of mirror matter in Twin Higgs models

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Zackaria Chacko ◽  
David Curtin ◽  
Michael Geller ◽  
Yuhsin Tsai
Keyword(s):  
Dark Matter ◽  
Cooling Rate ◽  
Direct Detection ◽  
The Earth ◽  
Electron Recoil ◽  
The Galaxy ◽  
The Masses ◽  
Event Rates ◽  
Modest Effect ◽  
Mirror Matter

Abstract We explore the possibility of discovering the mirror baryons and electrons of the Mirror Twin Higgs model in direct detection experiments, in a scenario in which these particles constitute a subcomponent of the observed DM. We consider a framework in which the mirror fermions are sub-nano-charged, as a consequence of kinetic mixing between the photon and its mirror counterpart. We consider both nuclear recoil and electron recoil experiments. The event rates depend on the fraction of mirror DM that is ionized, and also on its distribution in the galaxy. Since mirror DM is dissipative, at the location of the Earth it may be in the form of a halo or may have collapsed into a disk, depending on the cooling rate. For a given mirror DM abundance we determine the expected event rates in direct detection experiments for the limiting cases of an ionized halo, an ionized disk, an atomic halo and an atomic disk. We find that by taking advantage of the complementarity of the different experiments, it may be possible to establish not just the multi-component nature of mirror dark matter, but also its distribution in the galaxy. In addition, a study of the recoil energies may be able to determine the masses and charges of the constituents of the mirror sector. By showing that the mass and charge of mirror helium are integer multiples of those of mirror hydrogen, these experiments have the potential to distinguish the mirror nature of the theory. We also carefully consider mirror plasma screening effects, showing that the capture of mirror dark matter particles in the Earth has at most a modest effect on direct detection signals.

scholarly journals Scaleheights of Low Mass Stars from the Luminosity Function of the Local White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 152-155
Author(s):  
N.C. Rana
Keyword(s):  
Lower Bound ◽  
White Dwarf ◽  
Molecular Clouds ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Fold Increase ◽  
Low Mass Stars ◽  
Dynamical Interaction ◽  
Constant Rate ◽  
Low Mass

It is shown that a combination of the observed luminosity function of the local white dwarfs and the theoretical cooling rates of a typical white dwarf suggests an approximately constant rate of formation of the white dwarfs. This rate is found to be about a factor of three lower than the observed birthrate of their immediate progenitors. This discrepancy is here interpreted as a three-fold increase in the scaleheight of the white dwarfs due to dynamical interaction with stars, molecular clouds; an average white dwarf being much more aged than an average progenitor. Since the low mass stars on an average are even slightly more long-lived than these white dwarfs, one can place a lower bound on the scaleheights of the low mass stars to be given by the required scaleheights of the white dwarfs, which is, according to the present work, 660 pc in the solar neighbourhood.

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