Conveners
Parallel 2: Cosmology Dark Matter
- Luigi Pilo (Istituto Nazionale di Fisica Nucleare)
Parallel 2: Cosmology Dark Matter
- Luigi Pilo (Istituto Nazionale di Fisica Nucleare)
Parallel 2: Theory
- Fabrizio Nesti (Istituto Nazionale di Fisica Nucleare)
Parallel 2: Theory
- Nicola Rossi (Istituto Nazionale di Fisica Nucleare)
Parallel 2: Astrophysical observations
- Riccardo Biondi (Istituto Nazionale di Fisica Nucleare)
Parallel 2: Indirect detection
- Giulia Pagliaroli (Istituto Nazionale di Fisica Nucleare)
Parallel 2: Indirect detection
- Carmelo Evoli (Gran Sasso Science Institute)
In this presentation, I will investigate the influence of the reheating temperature of the visible sector on the freeze-in dark matter (DM) benchmark model for direct detection experiments, where DM production is mediated by an ultralight dark photon. I will consider a new regime for this benchmark where the initial temperature of the thermal Standard Model (SM) bath to be below the DM mass....
Primordial Black Holes (PBHs) may exist, possibly contributing to the Dark Matter abundance. We will revisit some key aspects of the cosmological bound on a subdominant population of heavy PBHs, originating from the accurate measurement of the anisotropies in the Cosmic Microwave Background (CMB). We will analyze the role of accretion physics, with particular focus on the interplay between...
Strong gravitational lensing provides a direct, purely gravitational method to infer the properties of dark matter halos and thereby constrain the mass, formation mechanism, and possible self-interactions of the dark matter. Many strong lenses appear as four lensed images of a background quasar alongside spatially-resolved light from the quasar host galaxy that we observe as spectacular,...
The most widely accepted model to describe our Universe is the Cold Dark Matter model (CDM), where the WIMPs scenario is favored for theoretical and experimental reasons. However, despite many experiments, WIMPs have still not been detected. Moreover, as observations and simulations at galactic scales have improved, several challenges remain such as the core-cusp problem and the missing...
Some of the gravitational-wave (GW) events detected by LIGO-Virgo might be black holes of primordial origin. However, unveiling the origin of these events is challenging, notably if no multi-wavelength counterpart is detected.
One important diagnostic tool is the coalescing binary distribution with respect to the large scale structures (LSS) of the universe, which we quantify via the...
The small-scale structure within the Galactic dark matter halo offers a variety of opportunities to test the nature of dark matter, which can be traced by galaxy observations. In particular, models that enhance or suppress the formation of structure will affect the abundance and concentration of dark matter halos. This leads to a distinct signature in local dwarf galaxy observations. In...
In our present paradigm of galaxy formation, the onset of structure is brought about via the gravitational collapse of dark matter, which subsequently acts as the scaffolding for the visible universe. Decades of numerical simulations have established several features of the dark matter model: the formation of haloes, and how their structure and abundance are influenced by the particle physics...
Self-interacting dark matter (SIDM) has been proposed to solve small-scale problems in ΛCDM cosmology. Constraints on the self-interaction cross-section of dark matter have been derived assuming that the self-interaction cross-section is independent of velocity. However, a velocity-dependent cross-section is more natural in most theories of SIDM. Using idealized N-body simulations without...
Cosmological simulations provide a self-consistent framework to study the complex dynamics within galaxies. These simulations are crucial as they examine the interconnected evolution of galactic components. Recent advancements in numerical simulations have significantly enhanced our understanding of baryonic physics—such as stellar processes and interstellar medium dynamics—and their role in...
The current $\Lambda$CDM framework predicts the formation of density cusps in the centre of the first dark matter haloes, which would be able to survive until $z=0$. More specifically, we could find a large number of these prompt cusps with Earth-like masses, which can populate the Milky Way. However, stellar encounters and/or tidal forces might destroy or deplete these structures. In this...
All of the significant evidence for dark matter observed thus far has been through its gravitational interactions. After 40 years of direct detection experiments, the parameter space for Weakly Interacting Massive Particles (WIMPs) as dark matter candidates is rapidly approaching the neutrino floor. In this light, we consider a dark sector that is strongly decoupled from the visible sector,...
Milgromian dynamics (MOND) is a major alternative to non-baryonic particle dark matter, proposed by Moti Milgrom in 1983. In this invited talk, I will review the multiple successful predictions that MOND had on galaxy scales, as well as the long-standing challenges it faces on galaxy-cluster and cosmological scales. In particular, I will describe the dynamical regularities and empirical laws...
If the dynamics of a disc galaxy is analysed from a general-relativistic viewpoint (GR), it turns out in general that the solution cannot be approximated by Newtonian theory, as is usually believed. Even under the simplifying assumptions of stationarity, axisymmetry and zero pressure (i.e. the velocity dispersion is neglected), non-Newtonian features can arise, which are ascribed to the...
We present from first principles, under the Schwinger-Keldysh path integral formalism, equations for bosonic, non-relativistic and self-interacting dark matter which can include both a condensed, low momentum “fuzzy” component and one with higher momenta that may be approximated as a collection of particles. The equations can describe both CDM and Fuzzy Dark Matter in a unified way and it can...
Pseudo-scalar particles, like QCD axions and Axion-like-Particles (ALPs), emerge in many extension of the Standard Model and have been recognized to be among the best Dark Matter candidates. Even if very weakly interacting, ALPs can be copiously in the core of massive stars at the end of their life. In this regard, Core-Collapse Supernovae (SNe) are expected to be powerful sources of novel...
A wide range of dark matter candidates have been proposed and are actively being searched for in a large number of experiments, both at high (TeV) and low (sub meV) energies. One dark matter candidate, a deeply bound uuddss sexaquark, S , with mass $\sim$ 2 GeV,
(having the same quark content as the hypothesized H-dibaryon, but long lived) is particularly difficult to explore experimentally....
We explore extensive N-body simulations with two-component cold dark-matter candidates. We delve into the temperature evolution, power spectrum, density perturbation, and maximum circular velocity functions. We find that the substantial mass difference between the two species and the annihilation of the heavier components to the lighter ones effectively endow the latter with warm...
The dark pion, $\pi_{D}$, is generally the lightest meson of strongly interacting dark sectors, which makes it a popular dark matter candidate. However, it is facing the challenge of simultaneously reproducing the relic abundance and satisfying constraints on dark matter self-interaction from the Bullet Cluster. This challenge can be overcome by considering additional light mesons of the dark...
Conventional methods for elucidating the behavior of Dark Matter (DM), such as effective field theory (EFT) and simplified models, have inherent limitations, including their limited applicability in LHC searches for DM and lack of generality, respectively. In this study, we propose a hybrid formulation aimed at reconciling these shortcomings by addressing both generality and applicability at...
Sub-GeV dark matter (DM) has been gaining significant interest in recent years, since it can account for the thermal relic abundance while evading nuclear recoil direct detection constraints. Such light DM must carry a larger energy to be probed, either directly or through missing energy/momentum, making beam dump and fixed target experiments ideal for this mass range. Here, we extend the...
WIMPs are one of the most popular classes of DM candidates. However, strong tensions arise because of negative signals from Direct Detection (DD) experiments. Several WIMP modes nevertheless exist, which, until present times, could overcome this issue as the interactions relevant for DD emerge at the one loop level. I will provide an overview of such models discussing the capability of current...
Various experiments have confirmed with good accuracy that all flavor violating phenomena are consistent with the predictions in the Standard Model (SM) of particle physics. This empirical fact encourages us to construct new physics models based on the assumption of the Minimal Flavor Violation (MFV), which dictates that new physics interactions respect a quark flavor symmetry with the only...
We study the sterile neutrino dark matter produced by the freeze-in mechanism through feeble $U(1)_{B-L}$ gauge interactions. By taking account of the contributions from the on-shell B-L scalar boson (inverse) decay and the single Z' boson production properly, we find that the cosmologically-interesting gauge coupling of $U(1)_{B-L}$ is smaller than $\mathcal{O}(10^{-10})$ if the B-L scalar...
Abstract: It has been suggested that the Galactic Center gamma-ray excess could be produced by a large number of centrally-located millisecond pulsars. The fact that no such pulsar population has been detected implies that these sources must be very faint and very numerous. Using Fermi’s recently released Third Pulsar Catalog, we measured the luminosity function of the millisecond pulsars in...
A galactic halo population of Primordial black holes (PBH) are a simple solution to the dark matter (DM) problem. Being dark, massive and non-baryonic, the PBH fits within the phenological traits that define Cold Dark Matter, and may exist in large numbers in the dark halos of spiral galaxies. Gravitational microlensing is among the most productive experimental avenues to constrain the...
The James Webb Space Telescope (JWST) has dramatically advanced our understanding of cosmic history, revealing new aspects of dark matter (DM) phenomena, particularly through our studies on Primordial Black Holes (PBHs) and Supermassive Dark Stars (SMDSs). These studies enhance our knowledge of the dark sector's role in the early universe and serve as an indirect probe for DM.
Our research...
Launched at the end of 2021, the James Webb Space Telescope (JWST) has already begun to revolutionize our view of the cosmic dawn era. Specifically, it discovered an unexpectedly large number of extremely bright objects in the sky from the early Universe, whose light was emitted more than thirteen billion years ago. If these objects are interpreted as some of the first galaxies ever...
Dark matter can be captured in stars and annihilate, providing the star with a new energy source in addition to nuclear fusion. This significantly changes stellar evolution at the Galactic Center, where the dark matter density is extremely high. As dark matter burning replaces nuclear fusion partially or completely, stars become longer-lived, as they use up hydrogen more conservatively, or...
Recent observations from optical surveys have discovered the presence of a multitude of ultra-faint compact stellar systems (UFCSs) orbiting the Milky Way (MW) that have the potential to be the most compact and faintest galaxies observed so far. If they were confirmed to be dark matter (DM) dominated, these objects would be ideal for indirect searches of DM annihilation, due to their proximity...
The energy spectra of particles produced from dark matter (DM) annihilation or decay are one of the fundamental ingredients to calculate the predicted fluxes of cosmic rays and radiation used for indirect DM detection. We revisit the calculation of the source spectra for annihilating and decaying DM employing the Vincia shower algorithm in Pythia to include QED and QCD final state radiation...
The two most favored explanations of the Fermi Galactic Center gamma-ray excess (GCE) are millisecond pulsars and self annihilation of the smooth dark matter halo of the galaxy. In order to distinguish between these possibilities, we would like to optimally use all information in the available data, including photon direction and energy information.
To date, analyses of the GCE have...
The gamma-ray Fermi-LAT Galactic centre excess (GCE) has puzzled scientists for over 15 years. Despite ongoing debates about its properties, and especially its spatial distribution, its nature remains elusive. We scrutinize how the estimated spatial morphology of this excess depends on models for the Galactic diffuse emission, focusing particularly on the extent to which the Galactic plane and...
Recently, Tibet AS$_\gamma$ and LHAASO have observed very high energy diffuse gamma rays in the Galactic place between 10 TeV and 1 PeV energies. In our work, we utilize these observations to search for dark matter decay or annihilation signals to Standard Model particles. In addition to the primary gamma-ray originating from various Standard Model particles, we also include secondary...
Tentative observations of cosmic-ray antihelium by the AMS-02 collaboration have re-energized the quest to use antinuclei to search for physics beyond the standard model. However, our transition to a data-driven era requires more accurate models of the expected astrophysical antinuclei fluxes. We use a state-of-the-art cosmic-ray propagation model, fit to high-precision antiproton and...
Cosmic-ray antimatter, particularly low-energy antideuterons, constitute a sensitive probe of dark matter annihilating in our Galaxy. We study this smoking-gun signature and explore its complementary to indirect search via cosmic-ray antiprotons. We revisit the Monte Carlo simulation of antideuteron coalescence and cosmic-ray propagation, allowing us to assess uncertainties from both...
The General Antiparticle Spectrometer (GAPS) is a balloon-borne experiment designed to perform
low-energy cosmic-ray antinuclei measurements searching for indirect signatures of dark matter.
A wide range of well-motivated dark matter models predicts antideuteron and antihelium fluxes
about two orders of magnitude above the expected astrophysical background below 250 MeV/n.
Thanks to a...
We discuss the connection of the Pierre Auger Observatory data with a large class of dark matter models based on the early-universe generation of super-heavy particles, their role in the solution of the dark matter problem, highlighting the remarkable constraining capabilities of the Auger observations.
Galaxy clusters are the largest gravitationally bound structures in the Universe, being completely dark matter (DM) dominated objects. The expected gamma-ray flux from annihilation/decay of DM depends on the target's DM density and its distance to Earth. Thus, for DM decay, local galaxy clusters yield the highest expected fluxes compared to other possible targets, as they are the most massive...
Numerous observations point towards the existence of dark matter (DM) at astrophysical and cosmological scales, yet the fundamental nature of this elusive component of our universe remains unknown. Theory and simulations of galaxy formation predict that DM should cluster on small scales in bound structures called sub-halos or DM clumps. Sub-halos are abundant in the Galaxy and can produce...
In this talk, we investigate the discovery potential of low-mass Galactic dark matter (DM) subhaloes for indirect searches of DM. We use data from the Via Lactea II (VL-II) N-body cosmological simulation, which resolves subhaloes down to $\mathcal{O}(10^4)$ solar masses and it is thus ideal for this purpose.
First, we characterize the abundance, distribution and structural properties of the...
Neutron stars (NSs) are promising cosmic laboratories to test the nature of dark matter (DM). DM captured by the strong gravitational field of these stellar remnants transfers its kinetic energy to the star through subsequent collisions with the star constituents. Further DM annihilation can add extra heating. This can produce anomalous heating of old neutron stars. While DM deposits its...
We explore the $511$ keV emission associated to sub-GeV dark matter (DM) particles that can produce electron-positron pairs and form positronium after thermalizing. We use $\sim16$ yr of SPI data from INTEGRAL to constrain DM properties, including the full positron propagation and losses, and the free electron density suppression away from the Galactic plane. We show that the predicted...
We discuss a novel decay process for dark matter searches known as the dark photon-photon trident, where a dark photon can interact with Standard Model particles through kinetic mixing with the visible photon, producing three-photon final states. Indirect searches for this process are categorized into two scenarios. Firstly, dark photons can be produced by dark matter annihilation in celestial...
The upcoming GRAMS (Gamma-Ray and AntiMatter Survey) experiment is one of the NASA Physics of the Cosmos suborbital missions. GRAMS aims to provide excellent sensitivity to gamma rays in the poorly explored MeV region often referred to as the “MeV gap” and to antideuteron/antihelium for an essentially ‘background-free’ indirect dark matter search. Utilizing Liquid Argon Time Projection Chamber...
