Gamma-ray lines constitute a smoking gun signature for annihilating dark matter particles. Imaging Atmospheric Cherenkov Telescopes and satellites have searched for such signals but null results have been reported thus far. We take advantage of the expected gamma-ray flux sensitivity of the Cherenkov Telescope Array Observatory (CTAO) toward the direction of the Galactic Centre and Dwarf Galaxies and its exquisite energy resolution to derive upper limits on fermionic and scalar dark matter annihilations into gamma-ray lines. We consider the lowest-order effective operators for scalar and fermion dark matter, and derive limits on the energy scale using the recent CTAO projected sensitivity. Putting our findings into perspective with existing limits from direct and indirect detection experiments, we conclude that CTAO will either play a complementary role or be a discovery channel for dark matter signals.
Recent radio observations have obtained stringent constraints for annihilating dark matter. In this article, we use the radio continuum spectral data of the Large Magellanic Cloud (LMC) to analyze the dark matter annihilation signals. We have discovered a slightly positive signal of dark matter annihilation with a $1.5σ$ statistical significance. The overall best-fit dark matter mass is $m_{\rm DM} \approx 90$ GeV, annihilating via $b\bar{b}$ channel. We have also constrained the $3σ$ lower limits of dark matter mass with the standard thermal dark matter annihilation cross section for the $e^+…
Dark Matter and Galaxy Cross-Correlations with the Cherenkov Telescope Array Observatory
Flatiron Institute（平顿研究所）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；University of Chicago, Kavli Institute for Cosmological Physics（芝加哥大学卡弗里宇宙物理学研究所）；University of Nova Gorica, Center for Astrophysics and Cosmology（新戈里察大学天体物理学与宇宙学中心）；Instituto de Física Corpuscular (IFIC), University of Valencia and CSIC（瓦伦西亚大学及西班牙高等科研理事会粒子物理研究所（IFIC））；Dipartimento di Fisica, Università degli Studi di Torino（都灵大学物理系）；INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Torino（意大利国家核物理研究所都灵分部）；INAF – Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Torino（意大利国家天体物理都灵天文台）
Recent gamma-ray and radio studies have obtained some stringent constraints on annihilating dark matter properties. However, only a few studies have focussed on using X-ray data to constrain annihilating dark matter. In this article, we perform the X-ray analysis of annihilating dark matter using the data of the Omega Centauri cluster. If dark matter is the correct interpretation of the non-luminous mass component derived in the Omega Centauri cluster, the conservative lower limits of thermal dark matter mass annihilating via the $τ^+τ^-$, $b\bar{b}$ and $W^+W^-$ channels can be significantly …
If the gamma-ray excess from the galactic center reported by Fermi-LAT is a signal from annihilating dark matter, one must question why a similar excess has not been observed in dwarf spheroidal galaxies. We use this observation to place constraints on the density profile of dwarf spheroidal galaxies under the assumption that the galactic center excess is in fact a signal from annihilating dark matter. We place constraints on the generalized NFW parameter $γ$ and the Einasto profile parameter $α$ which control the logarithmic slope of the inner regions of the halo's density profile. We determi…
The Fermi LAT collaboration has recently presented constraints on the gamma-ray signal from annihilating dark matter using separate analyses of a number of dwarf spheroidal galaxies. Since the expected annihilation signal has the same physical properties regardless of the target (except for a normalization scale), it is possible to enhance the constraining power using a combined analysis, the initial results of which will be presented here.
It has been long discussed that cosmic rays may contain signals of dark matter. In the last couple of years an anomaly of cosmic-ray positrons has drawn a lot of attentions, and recently an excess in cosmic-ray anti-proton has been reported by AMS-02 collaboration. Both excesses may indicate towards decaying or annihilating dark matter with a mass of around 1-10 TeV. In this article we study the gamma rays from dark matter and constraints from cross correlations with distribution of galaxies, particularly in a local volume. We find that gamma rays due to inverse-Compton process have large inte…
Past studies have identified a spatially extended excess of $\sim$1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. We revisit and scrutinize this signal with the intention of further constraining its characteristics and origin. By applying cuts to the \textit{Fermi} event parameter CTBCORE, we suppress the tails of the point spread function and generate high resolution gamma-ray maps, enabling us to more easily separate the various gamma-ray components. Within these maps, we find the GeV excess to be robust…
Celestial objects such as stars and planets might be able to capture a large amount of dark matter particles through dark matter-nucleon scattering. Many previous studies have considered different celestial objects such as the Sun and the Earth as natural dark matter detectors and obtained some stringent bounds of the dark matter-nucleon scattering cross section. In this study, we use the $\sim 10$ MeV electron neutrino flux limits obtained by the Super-Kamiokande experiment and consider the Earth as a large natural dark matter detector to constrain the dark matter-nucleon scattering cross sec…
Dark matter (DM) particles captured by the Sun can produce high energy electrons outside the Sun through annihilating into meta-stable mediators. The corresponding cosmic-ray electron signals observed by the space-based experiments will be time dependent due to the orbital motion of the space-based detectors. The shape of this time dependence is predictable given the orbital information of the detectors. Since the high-energy CR electron (with energy E>100 GeV) fluxes are expected to be constant in time, non-observation of such time variation can be used to place upper limits on the DM annihil…
We present constraints on decaying and annihilating dark matter (DM) in the 4 keV to 10 GeV mass range, using published results from the satellites HEAO-1, INTEGRAL, COMPTEL, EGRET, and the Fermi Gamma-ray Space Telescope. We derive analytic expressions for the gamma-ray spectra from various DM decay modes, and find lifetime constraints in the range 10^24-10^28 sec, depending on the DM mass and decay mode. We map these constraints onto the parameter space for a variety of models, including a hidden photino that is part of a kinetically mixed hidden sector, a gravitino with R-parity violating d…
The rapid rise in the cosmic ray positron fraction above 10 GeV, as measured by PAMELA and AMS, suggests the existence of nearby primary sources of high energy positrons, such as pulsars or annihilating/decaying dark matter. In contrast, the spectrum of secondary positrons produced through the collisions of cosmic rays in the interstellar medium is predicted to fall rapidly with energy, and thus is unable to account for the observed rise. It has been proposed, however, that secondary positrons could be produced and then accelerated in nearby supernova remnants, potentially explaining the obser…
We analyze the first two years of data from the Fermi Gamma Ray Space Telescope from the direction of the inner 10 degrees around the Galactic Center with the intention of constraining, or finding evidence of, annihilating dark matter. We find that the morphology and spectrum of the emission between 1.25 degrees and 10 degrees from the Galactic Center is well described by a the processes of decaying pions produced in cosmic ray collisions with gas, and the inverse Compton scattering of cosmic ray electrons in both the disk and bulge of the Inner Galaxy, along with gamma rays from known points …
We discuss ILC measurements for a specific MSSM scenario with CP phases, where the lightest neutralino is a good candidate for dark matter, annihilating efficiently through t-channel exchange of light staus. These prospective (CP-even) ILC measurements are then used to fit the underlying model parameters. A collider prediction of the relic density of the neutralino from this fit gives 0.116<Omega h^2<0.19 at 95% CL. CP-odd observables, while being a direct signal of CP violation, do not help in further constraining Omega h^2. The interplay with (in)direct detection of dark matter and with meas…
The observation of a sharp spectral feature in the gamma-ray sky would be one of the cleanest ways to identify dark matter and pinpoint its properties. Over the years a lot of attention has been paid to two specific features, namely gamma-ray lines and internal bremsstrahlung. Here, we explore a third class of spectral signatures, box-shaped gamma-ray spectra, that naturally arise in dark matter cascade annihilations or decays into intermediate particles that in turn decay into photons. Using Fermi-LAT data, we derive constraints on the dark matter parameter space for both annihilating and dec…
Recent radio-frequency probes, with the ATCA and ASKAP telescopes, have proven themselves to be at the forefront of placing indirect limits on the properties of dark matter. The latter being able to substantially exceed the constraining power of Fermi-LAT data. However, these observations were based only on dwarf galaxies, where magnetic field uncertainties are large. Here we re-examine the case for galaxy clusters, often ignored due to substantial diffuse radio backgrounds, by considering the extrapolation of known cluster surface brightness profiles down to scales observable with MeerKAT. De…
The latest years have seen steady progresses in WIMP dark matter (DM) searches, with hints of possible signals suggested by both direct and indirect detection experiments. Antiprotons can play a key role validating those interpretations since they are copiously produced by WIMP annihilations in the Galactic halo, and the secondary antiproton background produced by Cosmic Ray (CR) interactions is predicted with fair accuracy and matches the observed spectrum very well. Using the publicly available numerical DRAGON code, we reconsider antiprotons as a tool to constrain DM models discussing its p…
Heavy dark matter in rapidly evolving massive stars
Fermi National Accelerator Laboratory（费米国家加速器实验室）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Loyola University Chicago（芝加哥洛约拉大学）；Northwestern University（西北大学）；ARC Centre of Excellence for Dark Matter Particle Physics, Department of Physics, University of Adelaide（阿德莱德大学物理系暗物质粒子物理学卓越研究中心）
