Conveners
Dark matter
- Lina Necib (MIT)
Dark matter
- C Eric Dahl (Northwestern University)
Dark matter
- dan hooper
Dark matter
- Francesca Calore (LAPTh, CNRS)
Dark matter
- C Eric Dahl (Northwestern University)
Dark matter
- Kerstin Perez (MIT)
Dark matter
- Benjamin Safdi (massachusetts institute of technology)
Dark matter
- Francesca Calore (LAPTh, CNRS)
Dark matter
- Kerstin Perez (MIT)
Dark matter
- Francesca Calore (LAPTh, CNRS)
Dark matter
- Benjamin Safdi (massachusetts institute of technology)
The rotation curves of spiral galaxies exhibit a diversity that has
been difficult to understand in the cold dark matter (CDM) paradigm.
In this talk, I will show that the self-interacting dark matter (SIDM)
model provides excellent fits to the rotation curves of a sample of
galaxies with asymptotic velocities in the 25 to 300 km/s range that
exemplify the full range of diversity. We only...
While the $\Lambda$CDM paradigm has been extremely successful in matching observations of dark matter structure at large scales, several discrepancies between observations of dark matter structures at smaller scale (galactic and below) and $\Lambda$CDM's predictions have motivated particle physicists to consider an self-interacting dark matter (SIDM) as a possible solution. In this talk I will...
While the LCDM model has been wildly successful at explaining structure on large scales, it fails to do so on small scales---dark matter halos of scales comparable to that of galaxy clusters and smaller are more cored and less numerous than LCDM predicts. One potential solution challenges the canonical assumption that dark matter is collisionless and instead assumes that it is...
A general mechanism for thermal production of dark matter (DM) via 3-to-2 scatterings, or other higher-order interactions, allows for sub-GeV dark matter and strong self-interactions that meet existing constraints but have the potential to explain mysteries with cold DM and structure formation. In such models, so-called Strongly Interacting Massive Particles (SIMPs), a correct thermal average...
The thermal relic density of dark matter is conventionally set by two-body annihilations. We point out that in many simple models, 3→2 annihilations can play an important role in determining the relic density over a broad range of model parameters. This occurs when the two-body annihilation is kinematically forbidden, but the 3→2 process is allowed; we call this scenario "Not-Forbidden Dark...
The existence of dark matter is one of the few solid hints for physics beyond the standard model. If dark matter has indeed particle nature, then direct detection via scattering on atomic nuclei is one of the most promising discovery channels. In order to connect this nonrelativistic process with astrophysical and collider searches, as well as UV model building, a consistent setup of effective...
We study simplified models of flavoured dark matter in the framework of Dark Minimal Flavour Violation. In this setup the coupling of the dark matter flavour triplet to SM quark triplets constitutes the only new source of flavour and CP violation. The parameter space of the model is restricted by LHC searches with missing energy final states, by neutral meson mixing data, by the observed dark...
An important source of background in direct searches for low-mass dark matter particles are the energy deposits by small-angle scattering of environmental γ rays. We report detailed measurements of low-energy spectra from Compton scattering of γ rays in the bulk silicon of a charge-coupled device (CCD). Electron recoils produced by γ rays from 57Co and 241Am radioactive sources are measured...
Many dark matter interaction types lead to annihilation processes which suffer from $p$-wave suppression or helicity suppression, rendering them sub-dominant to unsuppressed $s$-wave processes. We demonstrate that the natural inclusion of dark initial state radiation can open an unsuppressed $s$-wave annihilation channel, and thus provide the dominant dark matter annihilation process for...
The Light Dark Matter eXperiment (LDMX) proposes a high-statistics search for low-
mass dark matter at a new experimental facility, Dark Sector Experiments at LCLS-II
(DASEL), at SLAC. LDMX employs the missing momentum technique, where electrons
scattering in a thin target can produce dark matter via “dark bremsstrahlung” that are
not observed in the detector. To identify these rare signal...
We consider the indirect detection signals for models containing a fermionic DM candidate, a dark gauge boson, and a dark Higgs field. Compared with a model containing only a dark matter candidate and vector mediator, the addition of the scalar provides a mass generation mechanism for the dark sector particles which, in some cases, is required in order to avoid unitarity violation at high...
Charge-coupled devices (CCDs) are excellent particle detectors with the ability to probe a wide range of low-mass dark matter candidates. Initially developed for use in astronomy, CCDs have low per-pixel noise and excellent spatial resolution, giving them unique background discrimination and low (<100eV) energy thresholds. I will present the status of the DAMIC100 experiment, an ongoing direct...
The origin of the Galactic Center Gamma-Ray excess still remains unclear. Astrophysical interpretations have been proposed, but these explanations require either a significant degree of tuning or a large population of millisecond pulsars that have a very different population than that observed in globular clusters or near the Milky Way. If the dark matter annihilation interpretation is...
SuperCDMS (Cryogenic Dark Matter Search) has been one of the leading direct dark matter search experiments using low-temperature semiconductor detectors. The recoil energy induced by dark matter scattering inside the detector is measured using phonon (lattice vibration) and ionization signals. CDMSlite (low-ionization threshold experiment) within SuperCDMS Soudan has the best dark...
The MiniBooNE experiment at Fermilab performed the first dedicated search for accelerator proton beam produced dark matter. By steering the 8 GeV beam into an iron beam dump, the neutrino production from charged meson decay was suppressed while the photon production from neutral mesons remained unchanged. According to hidden-sector vector portal models, the Standard Model photons kinetically...
So far, all evidence for the existence of dark matter is based on its gravitational interactions with the observable sector, and its precise particle nature remains mysterious. However, even if dark matter is stable against decay in flat spacetime, as commonly assumed in the literature, the presence of nonminimal couplings to gravity of the dark matter field can spoil this stability in curved...
Sterile neutrinos produced through resonant or non-resonant oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. Based on general considerations we find a thermalization mechanism which
can increase the yield after resonant and non-resonant production. At the same time, it alleviates
the growing tensions...
Scintillating bubble chambers are demonstrated to have clean separation between electron recoils and nuclear recoils down to a thermodynamic “Seitz” threshold of 2 keV with a prototype liquid xenon chamber developed at Northwestern University, as the former only produce scintillation light while the later produce both scintillation light and bubble nucleation. This clean separation is expected...
In this talk, I will present the application of Calogero's Variable Phase method for the determination of Sommerfeld Enhancement factors relevant for dark matter cross section calculations. In contrast to directly solving the radial Schrodinger equation, the evaluation using the Variable Phase Method offers a rapid and stable evaluation, even for multichannel systems. Time permitting, I will...
The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium detectors totalling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in...
The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important...
Strong gravitational lensing provides a means of measuring the halo mass function into regimes below which baryons are reliable tracers of structure. In this low mass regime (M_vir<10^9 M_sun), the microscopic characteristics of dark matter affect the predicted abundance of dark matter halos. Strong gravitational lensing has been limited by the small number of systems which can be used to...
Astrometry in the Gaia era will give an unprecedented amount of information about the full 6D phase space distribution of the local galactic halo. In this talk, I will use an analysis of vertical motions to show how the Gaia data will be sensitive to the presence of structures including dark disks (either from novel dark matter microphysics or from baryonic dragging.)
We present our first results from a deep LBT survey of dwarf satellites of nearby star-forming galaxies outside the local group. We present our candidates and report the number and distribution of satellites for our first system. We are sensitive to deep within the ultra faint dwarf and ultra diffuse galaxy regime outside. We discuss the implications of these new observations on the dark...
Deep optical imaging surveys have revealed a population of extremely low luminosity and dark matter dominated galaxies orbiting the Milky Way. The total number of Milky Way satellite galaxies and the demographics of this population are still largely unknown, in part, because of complex selection effects that limit our ability to detect the lowest surface brightness galaxies. The Dark Energy...
We identify new astrophysical signatures of NS-imploding DM, which could decisively test these hypotheses in the next few years.
First, NS-imploding DM forms ≪10−10 solar mass black holes inside NSs, thereby converting NSs into ∼1.5 solar mass BHs. This decreases the number of NS mergers seen by LIGO/VIRGO (LV) and associated merger kilonovae seen by telescopes like DES, BlackGEM, and ZTF,...
A largely model-independent probe of dark matter-nucleon interactions is proposed. Accelerated by gravity to relativistic speeds, local dark matter scattering against old neutron stars deposits kinetic energy that heats them to infrared blackbody temperatures. The resulting radiation could be detected by next generation telescopes such as James Webb, the Thirty Meter Telescope and the European...
New results from the Large Underground Xenon (LUX) detector, a 100-kg-scale, 2-phase xenon direct dark matter search experiment, will be shared. Dark matter, the missing ~25% of the mass-energy content of the universe, is sought in new ways, using effective field theory operators to extend the search to higher-mass Weakly Interacting Massive Particles (WIMPs), spin-dependent interaction...
Xenon-based dark matter experiments have been leading the field of direct detection for a decade now, as realized most recently by the PandaX, LUX, and now XENON1T results, setting increasingly stringent limits on WIMP scattering. The near-future commencement of construction of LUX and ZEPLIN’s 10-ton-scale scale-up, next-generation successor, LZ, will be discussed here. We plan on achieving...
Understanding the properties of dark matter particle is a fundamental problem in particle physics and cosmology. The search of dark matter particle scattering off nuclei target using ultra-low background detector is one of the most promising technology to decipher the nature of dark matter. The XENON1T experiment, which is a dual phase detector with ~2.0 tons of xenon running at the Gran Sasso...
The PandaX project consists of a series of xenon-based experiments, located at China JinPing underground Laboratory. The current experiment, PandaX-II, is a direct dark matter search experiment with a 500 kg-scale liquid xenon dual-phase time projection chamber. PandaX-II started physics data taking in 2016. In this talk we report latest results and the current status of the PandaX-II experiment.
The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei. The target material consists of scintillating CaWO$_4$ single crystals operated as cryogenic detectors at a temperature of ~10mK. For several years, these crystals have successfully been produced within the...
The PICO collaboration uses superheated fluid detectors to attempt to directly detect interactions between dark matter particles and ordinary matter. These detectors can be operated in conditions under which they are insensitive to gamma and beta radiation, typically the dominant backgrounds for direct dark matter searches.
The PICO-60 bubble chamber is located 2km underground at SNOLAB in...
Many extensions of the Standard Model of particle physics predict a parallel sector of at least one new U(1) symmetry, giving rise to hidden photons. If produced non-thermally in the early universe, these hidden photons can be candidate particles for cold Dark Matter. Hidden photons are expected to kinetically mix with regular photons. If hidden photons pass through a conducting surface a tiny...
Extragalactic galaxies and galaxy clusters are expected to be some of the brightest sources of dark matter annihilation on the sky. Further, catalogs such as the 2MASS survey, tell us where thousands of these objects are. The challenge, however, is that catalogs only detail a subset of the baryonic properties of these galaxies. In this talk I will outline how to map from a catalog of galaxies...
We perform a search for dark matter (DM) annihilation in nearby galaxies using 413 weeks of publicly-available Fermi Pass 8 gamma-ray data, utilizing a novel method that takes advantage of recently-developed galaxy group catalogs based on the 2MASS Redshift Survey. Having validated our method using N-body simulations, we construct nearly all-sky maps of an expected DM annihilation signal in...
Milky Way dwarf spheroidal satellite galaxies are the most dark-matter-dominated galaxies known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are one of the most promising targets for the indirect detection of dark matter annihilation via gamma rays. Indeed, Fermi-LAT observations of previously known dwarf galaxies have...
For models in which dark matter annihilation is Sommerfeld-enhanced, the annihilation cross section increases at low relative velocities.
Dwarf spheroidal galaxies (dSphs) have low characteristic dark matter particle velocities and are thus ideal candidates to study such models.
We model the dark matter phase space of dSphs as isotropic and spherically-symmetric and determine the $J$-factors...
The Milky Way's Galactic Center may harbor the signal of annihilating
dark matter in a gamma-ray excess, though dwarf galaxies remain dark
in their expected commensurate emission. We incorporate Milky Way dark
matter halo profile uncertainties, as well as an accounting of diffuse
gamma ray emission uncertainties in dark matter annihilation models
for the Galactic Center Extended gamma-ray...
We propose a novel method to search for signatures of dark matter annihilation in Galactic substructure using gamma-ray data from the $\it Fermi$ Large Area Telescope. The method takes advantage of the fundamentally different photon-count statistics that describe dark matter annihilation from a population of subhalos versus from the smooth Milky Way halo. In addition, it exploits differences...
In this talk, we discuss a scenario called late-decaying two-component dark matter (LD2DM), where the entire DM consists of two semi-degenerate species. Within this framework, the heavier species is produced as a thermal relic in the early universe and decays to the lighter species over cosmological timescales. Consequently, the lighter species becomes the DM which populates the universe...
The most dramatic "Sommerfeld enhancements'' of neutral-wino-pair annihilation occur when the wino mass is near a critical value where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold. Near a critical mass, low-energy winos can be described by a zero-range effective field theory in which the winos interact nonperturbatively through a contact interaction. The...
In this talk, I will discuss a class of models in which thermal dark matter is lighter than an MeV. If dark matter thermalizes with the Standard Model below the temperature of neutrino-photon decoupling, constraints from measurements of the effective number of neutrino species are alleviated. This framework motivates new experiments in the direct search for sub-MeV thermal dark matter and...
We investigate the feasibility of the indirect detection of dark matter in a simple model using the neutrino portal. The model is very economical, with right-handed neutrinos generating neutrino masses through the Type-I seesaw mechanism and simultaneously mediating interactions with dark matter. Given the small neutrino Yukawa couplings expected in a Type-I seesaw, direct detection and...
In this talk, I will show that metal poor halo stars have similar kinematics as dark matter in the solar neighborhood, using the hydrodynamic zoom-in simulation Eris of the Milky Way. Within this expectation, I extract the first empirically-determined dark matter velocity distribution using the velocity dispersions of the halo stars as measured by the Sloan Digital Sky Survey, and show that...
Predictions for direct dark matter searches rely on the knowledge of the local speed distribution of dark matter particles. This distribution can be derived within a dynamically constrained Milky Way mass model using the Eddington formalism or some extended versions of it. This method, however, can lead to unconsistent or unphysical solutions, depending on the details of the mass model. I will...
The interpretation of dark matter direct detection results is complicated due to the unknown distribution of dark matter in our local neighborhood. Astrophysical uncertainties in the dark matter distribution are a major barrier preventing a precise determination of the properties of the dark matter particle. High resolution cosmological simulations of galaxy formation including baryons have...
Many dark matter studies have considered indirect detection (χχ → ff), direct detection (χf →χf ), and collider searches (ff → χχ). We propose a new strategy in searching for dark matter elastic cross section by considering cosmic-ray propagation in the galactic dark matter halo. We find that cosmic rays can lose significant fraction of their energy through scattering with dark matter (fχ → fχ)....
In this talk, we discuss the effects of a non-negligible threshold energy on our model-independent methods developed for reconstructing WIMP properties by using measured recoil energies in direct Dark Matter detection experiments directly. Our expressions for reconstructing the mass and the (ratios between the) spin-independent and the spin-dependent WIMP-nucleon couplings have been modified....
We discuss direct detection of WIMP dark matter in two benchmark cases: a Majorana fermion that primarily interacts via the Z-boson, and a Majorana fermion whose relic density is primarily set via co-annihilations with colored partners. We discuss the Z-mediated case with reference to a simple UV-completion, the singlet doublet model. We discuss the co-annihilation case with reference to...
ABRACADABRA is a proposed experiment to search for ultralight (10^-14 - 10^-6 eV) axion dark matter. When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current...
The Axion Dark Matter Experiment, ADMX, is taking data with sensitivity to a possible dark matter candidate that would also solve the strong-CP problem of QCD. The experiment, it's status, and preliminary results will be presented along with a path to cover much of the highly motivated parameter space.
The nature of dark matter (DM) remains one of the fundamental questions in cosmology. Axions are one of the current leading candidates for the hypothetical, non-baryonic DM. Especially in the light of LHC slowly closing in on WIMP searches, axions and axion-like particles (ALPs) provide a viable alternative approach to solving the dark matter problem. The fact that makes them very appealing is...
The Axion Resonant InterAction Detection Experiment (ARIADNE) will search for evidence of the QCD axion using nuclear magnetic resonance to search for a short-range spin-dependent interaction in the sub-millimeter range, which results from the Axion. ARIADNE features spin polarized 3He interacting with a rotating unpolarized tungsten mass as a probe for this interaction. We will outline the...
While the discovery of the Higgs boson at the LHC experimentally confirms the widely successful Standard Model (SM) of particle physics, the theory still falls short of explaining several fundamental features of our Universe. A major shortcoming is the SM’s silence on the nature of Dark Matter (DM). Currently, axions and WIMPs are the leading DM candidates with axions simultaneously addressing...
The number of nonrelativistic axions can be changed by inelastic reactions
that produce relativistic axions or photons.
Any even number of nonrelativistic axions can scatter inelastically into two relativistic axions. Any odd number of axions can annihilate into two photons.
This reaction produces a monochromatic radio-frequency signal at an odd-integer harmonic of the fundamental frequency...
ABRACADABRA10cm is a new experiment which seeks to detect
axion dark matter through its interactions with the electromagnetic field. The experiment, which is planned to start collecting data this year, will probe unstudied regions of axion parameter space and lay the groundwork for future, larger-scale efforts. I will discuss the results of numerical and analytical work...
One of the best current constraints for indirect detection of dark matter at the 1-100 GeV mass scale is the Fermi-LAT stacking analysis of satellite dwarf galaxies of the Milky Way. This constraint is based on observations in a very small fraction of the sky, whereas undetectable, dense dark matter structures are predicted to be distributed throughout the Milky Way halo. I will describe...
There is overwhelming evidence that non-baryonic dark matter constitutes ~85% of the mass in the Universe. Many promising dark matter candidates, like Weakly Interacting Massive Particles (WIMPs), are predicted to produce Standard Model particles like gamma rays via annihilation or decay. These gamma-rays would be observed by ground-based arrays like the High Altitude Water Cherenkov (HAWC)...
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 0.5 TeV - 100 TeV gamma-rays and cosmic-rays in the State of Puebla, Mexico at an altitude of 4100m. The HAWC observatory performed an indirect search for dark matter via GeV-TeV photons resulting from dark matter annihilation and decay considering various sources, including 15 dwarf...
In the current understanding of structure formation in the Universe, the Milky Way is embedded in a clumpy halo of dark matter (DM). Regions of higher DM density are expected to present an enhanced rate of annihilation into gamma-rays with respect to the smooth halo regions. These point-like gamma-ray fluxes can possibly be detected by gamma-ray observatories on Earth, like the forthcoming...
Well motivated dark matter particle models predict self-annihilating dark matter to yield Standard Model particles that can potentially be detected by astrophysical observations in systems such as dwarf galaxies, normal galaxies, and galaxy clusters. The potential emission from the charged particle byproducts of dark matter annihilation includes radio emission due to synchrotron radiation as...
The GAPS Experiment is the first experiment optimized specifically for low-energy antideuteron and antiproton cosmic-ray signatures. Low-energy antideuterons have been recognized as an extraordinarily low-background signature of new physics, and low-energy antiprotons are probes of both light dark matter and cosmic-ray propagation models. Together, these signatures offer a potential...
Energy injection from dark matter (DM) between recombination and reionization could affect the ionization and thermal history of the universe, leaving a distinctive imprint on the cosmic microwave background (CMB). Therefore, precise measurements of the temperature and polarization anisotropies of the CMB provide a powerful tool by which to constrain DM. In this talk, I will characterize the...
While constraints on primordial black holes as dark matter are strong over a wide mass range, a narrow window in the stellar-mass range remains relatively unconstrained. The recent discoveries of gravitational waves from merging black holes in roughly the 10-30 solar mass range has re-ignited the discussion of whether primordial black holes in this mass range could be a candidate for dark...
Supernova 1987A provides strong constraints on hidden-sector particles with masses below ~100 MeV. If such particles are produced in sufficient quantity, they reduce the cooling time of the supernova, in conflict with observations. We consider the resulting constraints on dark photons, milli-charged particles, and sub-GeV dark matter coupled to dark photons. For the first time, we include the...
Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The...
The era of precision cosmology has revealed that ~80% of the matter in the universe is dark matter. Two leading candidates, motivated by both particle and astro-physics, are Weakly Interacting Massive Particles (WIMPs) and axionlike particles (ALPs), both of which have distinct gamma-ray signatures. The Fermi Large Area Telescope (Fermi-LAT) Collaboration continues to search for WIMP and ALP...
The AMS-02 experiment has recently released a new measurement of the cosmic-ray antiproton spectrum. Assuming that cold dark matter (CDM) is made of self-annihilating particles, the AMS-02 data can be used to constrain the annihilation cross section. It is known however that CDM structures itself on scales much smaller than typical galaxies. This structuring translates into a very large...
