scholarly journals Millisecond Pulsars in the Galactic Bulge? An Extended Discussion on the Wavelet Analysis of the Fermi-LAT data

2016 ◽  
Vol 11 (S322) ◽  
pp. 193-196
Author(s):  
Richard Bartels ◽  
Christoph Weniger
Keyword(s):  
Dark Matter ◽  
Spectral Analysis ◽  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Point Source ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Supportive Evidence ◽  
Millisecond Pulsars ◽  
Extended Discussion

AbstractA clear excess in the Fermi-LAT data is present at energies around a few GeV. The spectrum of this so-called ’GeV excess’ is remarkably similar to the expected annihilation signal of WIMP dark matter. However, a large bulge population of millisecond pulsars living below the Fermi–LAT detection threshold could also explain the excess spectrum. In a recent work we optimized the search for sub-threshold sources, by applying a wavelet transform to the Fermi–LAT gamma-ray data. In the Inner-Galaxy the wavelet signal is significantly enhanced, providing supportive evidence for the point source interpretation of the excess. In these proceedings we will extent our previous work with a spectral analysis and elaborate on the potential contamination from substructures in the gas.

scholarly journals Gamma-Ray Sensitivity to Dark Matter Subhalo Modelling at High Latitudes

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 90 ◽  
Author(s):  
Francesca Calore ◽  
Moritz Hütten ◽  
Martin Stref
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Point Sources ◽  
Large Set ◽  
Case Scenario ◽  
Tidal Disruption ◽  
Dwarf Spheroidal Galaxies ◽  
Dark Matter Mass ◽  
The One

Searches for “dark” subhaloes in gamma-ray point-like source catalogues are among promising strategies for indirect dark matter detection. Such a search is nevertheless affected by uncertainties related, on the one hand, to the modelling of the dark matter subhalo distribution in Milky-Way-like galaxies, and, on the other hand, to the sensitivity of gamma-ray instruments to the dark matter subhalo signals. In the present work, we assess the detectability of dark matter subhaloes in Fermi-LAT catalogues, taking into accounts uncertainties associated with the modelling of the galactic subhalo population. We use four different halo models bracketing a large set of uncertainties. For each model, adopting an accurate detection threshold of the LAT to dark matter subhalo signals and comparing model predictions with the number of unassociated point-sources in Fermi-LAT catalogues, we derive upper limits on the annihilation cross section as a function of dark matter mass. Our results show that, even in the best-case scenario (i.e., DMonly subhalo model), which does not include tidal disruption from baryons, the limits on the dark matter parameter space are less stringent than current gamma-ray limits from dwarf spheroidal galaxies. Comparing the results obtained with the different subhalo models, we find that baryonic effects on the subhalo population are significant and lead to dark matter constraints that are less stringent by a factor of ∼2 to ∼5. This uncertainty comes from the unknown resilience of dark matter subhaloes to tidal disruption.

scholarly journals Searching for Gamma-Ray Millisecond Pulsars: Selection of Candidates Revisited

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 31
Author(s):  
Xuejie Dai ◽  
Zhongxiang Wang ◽  
Jithesh Vadakkumthani
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Previous Analysis ◽  
Test Statistic ◽  
Large Area ◽  
Millisecond Pulsars ◽  
Multi Wavelength ◽  
Γ Ray ◽  
Available Information ◽  
Selection Of

We are starting a project to find γ -ray millisecond pulsars (MSPs) among the unidentified sources detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope (Fermi), by radio observations. The selection of good candidates from analysis of the LAT data is an important part of the project. Given that there is more than 10 years worth of LAT data and the advent of the newly released LAT 8-year point source list (FL8Y), we have conducted a selection analysis, on the basis of our previous analysis, and report the results here. Setting the requirements for the unidentified sources in FL8Y of Galactic latitudes | b | > 5 ∘ and curvature significances >3 σ , there are 202 sources with detection signficances >6 σ . We select 57 relatively bright ones (detection significances >15 σ ) and analyze their 10.2 years of LAT data. Their variability is checked to exclude variable sources (likely blazars), test statistic maps are constructed to avoid contaminated sources, and curvature significances are re-obtained and compared to their γ -ray spectra to exclude non-significant sources. In the end, 48 candidates are found. Based on the available information, mostly from multi-wavelength studies, we discuss the possible nature of several of the candidates. Most of these candidates are currently being observed with the 65-meter Shanghai Tian Ma Radio Telescope.

scholarly journals Constraints to Dark Matter Annihilation from High-Latitude HAWC Unidentified Sources

Galaxies ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 5
Author(s):  
Javier Coronado-Blázquez ◽  
Miguel A. Sánchez-Conde
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Gamma Rays ◽  
High Latitude ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Dark Matter Annihilation ◽  
Annihilation Channel ◽  
Dark Matter Search ◽  
Spatially Extended

The Λ CDM cosmological framework predicts the existence of thousands of subhalos in our own Galaxy not massive enough to retain baryons and become visible. Yet, some of them may outshine in gamma rays provided that the dark matter is made of weakly interacting massive particles (WIMPs), which would self-annihilate and would appear as unidentified gamma-ray sources (unIDs) in gamma-ray catalogs. Indeed, unIDs have proven to be competitive targets for dark matter searches with gamma rays. In this work, we focus on the three high-latitude ( | b | ≥ 10 ) sources present in the 2HWC catalog of the High Altitude Water Cherenkov (HAWC) observatory with no clear associations at other wavelengths. Indeed, only one of these sources, 2HWC J1040+308, is found to be above the HAWC detection threshold when considering 760 days of data, i.e., a factor 1.5 more exposure time than in the original 2HWC catalog. Other gamma-ray instruments, such as Fermi-LAT or VERITAS at lower energies, do not detect the source. Also, this unID is reported as spatially extended, making it even more interesting in a dark matter search context. While waiting for more data that may shed further light on the nature of this source, we set competitive upper limits on the annihilation cross section by comparing this HAWC unID to expectations based on state-of-the-art N-body cosmological simulations of the Galactic subhalo population. We find these constraints to be particularly competitive for heavy WIMPs, i.e., masses above ∼25 (40) TeV in the case of the b b ¯ ( τ + τ − ) annihilation channel, reaching velocity-averaged cross section values of 2 × 10 − 25 ( 5 × 10 − 25 ) cm 3 ·s − 1 . Although far from testing the thermal relic cross section value, the obtained limits are independent and nicely complementary to those from radically different DM analyses and targets, demonstrating once again the high potential of this DM search approach.

scholarly journals On the origin of the gamma-ray emission from Omega Centauri: millisecond pulsars and dark matter annihilation

2021 ◽  
Vol 2021 (02) ◽  
pp. 010-010
Author(s):  
Javier Reynoso-Cordova ◽  
Oleg Burgueño ◽  
Alex Geringer-Sameth ◽  
Alma X. González-Morales ◽  
Stefano Profumo ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Dark Matter Annihilation ◽  
Millisecond Pulsars ◽  
Gamma Ray Emission

Classification of Acceleration Waveforms during Walking by Wavelet Transform

1997 ◽  
Vol 36 (04/05) ◽  
pp. 356-359 ◽  
Author(s):  
M. Sekine ◽  
M. Ogawa ◽  
T. Togawa ◽  
Y. Fukui ◽  
T. Tamura
Keyword(s):  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Center Of Gravity ◽  
Dynamic Responses ◽  
Sequential Data ◽  
Acceleration Signal ◽  
Continuous Dynamic

Abstract:In this study we have attempted to classify the acceleration signal, while walking both at horizontal level, and upstairs and downstairs, using wavelet analysis. The acceleration signal close to the body’s center of gravity was measured while the subjects walked in a corridor and up and down a stairway. The data for four steps were analyzed and the Daubecies 3 wavelet transform was applied to the sequential data. The variables to be discriminated were the waveforms related to levels -4 and -5. The sum of the square values at each step was compared at levels -4 and -5. Downstairs walking could be discriminated from other types of walking, showing the largest value for level -5. Walking at horizontal level was compared with upstairs walking for level -4. It was possible to discriminate the continuous dynamic responses to walking by the wavelet transform.

scholarly journals Spin-one dark matter and gamma ray signals from the galactic center

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
H. Hernández-Arellano ◽  
M. Napsuciale ◽  
S. Rodríguez
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Gamma Ray ◽  
Galactic Center ◽  
Photon Emission ◽  
Scalar Coupling ◽  
Initial State ◽  
Internal Bremsstrahlung ◽  
Resonance Effects ◽  
State Radiation

Abstract In this work we study the possibility that the gamma ray excess (GRE) at the Milky Way galactic center come from the annihilation of dark matter with a (1, 0) ⊕ (0, 1) space-time structure (spin-one dark matter, SODM). We calculate the production of prompt photons from initial state radiation, internal bremsstrahlung, final state radiation including the emission from the decay products of the μ, τ or hadronization of quarks. Next we study the delayed photon emission from the inverse Compton scattering (ICS) of electrons (produced directly or in the prompt decay of μ, τ leptons or in the hadronization of quarks produced in the annihilation of SODM) with the cosmic microwave background or starlight. All these mechanisms yield significant contributions only for Higgs resonant exchange, i.e. for M ≈ MH /2, and the results depend on the Higgs scalar coupling to SODM, gs. The dominant mechanism at the GRE bump is the prompt photon production in the hadronization of b quarks produced in $$ \overline{D}D\to \overline{b}b $$ D ¯ D → b ¯ b , whereas the delayed photon emission from the ICS of electrons coming from the hadronization of b quarks produced in the same reaction dominates at low energies (ω < 0.3 GeV ) and prompt photons from c and τ , as well as from internal bremsstrahlung, yield competitive contributions at the end point of the spectrum (ω ≥ 30 GeV ). Taking into account all these contributions, our results for photons produced in the annihilation of SODM are in good agreement with the GRE data for gs ∈ [0.98, 1.01] × 10−3 and M ∈ [62.470, 62.505] GeV . We study the consistency of the corresponding results for the dark matter relic density, the spin-independent dark matter-nucleon cross-section σp and the cross section for the annihilation of dark matter into $$ \overline{b}b $$ b ¯ b , τ+τ−, μ+μ− and γγ, taking into account the Higgs resonance effects, finding consistent results in all cases.

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