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The concentrations of the cuspy dark matter halos predicted by simulations of cold dark matter are related to the cosmology in which the halos form. Observational constraints on halo concentration therefore map into constraints on…

天体物理学 · 物理学 2009-11-07 S. McGaugh , M. Barker , E. de Blok

We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resultant gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the…

高能天体物理现象 · 物理学 2015-06-12 Kouichi Hirotani

We describe a simple model which explains the qualitative and (approximate) quantitative features of the distribution of orbital velocities of merging pairs of dark matter halos. Our model considers a primary dark matter halo as a perturber…

星系天体物理 · 物理学 2021-05-26 A. J. Benson

We introduce a new technique to constrain the line-of-sight integrated electron density of our Galactic halo $\text{DM}_\text{MW,halo}$ through analysis of the observed dispersion measure distributions of pulsars $\text{DM}_\text{pulsar}$…

星系天体物理 · 物理学 2020-06-09 E. Platts , J. Xavier Prochaska , Casey J. Law

The enormous range of X-ray luminosities among elliptical galaxies with similar optical luminosities can be attributed to large scatter and systematic variations in the dark halo mass determined from X-ray observations. The mean halo mass…

If a substantial fraction of the observed gamma-ray bursts originates within an extended Galactic halo then their spatial distribution should deviate slightly from spherical symmetry in a very particular way which involves features both in…

天体物理学 · 物理学 2007-05-23 Eyal Maoz

We explore the phase-space structure of nearby halo stars identified kinematically from Gaia DR2 data. We focus on their distribution in velocity and in "integrals of motion" space as well as on their photometric properties. Our sample of…

星系天体物理 · 物理学 2018-06-27 Helmer H. Koppelman , Amina Helmi , Jovan Veljanoski

Giant radio halos are Mpc-scale diffuse radio sources associated with the central regions of galaxy clusters. The most promising scenario to explain the origin of these sources is that of turbulent re-acceleration, in which MeV electrons…

高能天体物理现象 · 物理学 2017-07-26 D. Eckert , M. Gaspari , F. Vazza , F. Gastaldello , A. Tramacere , S. Zimmer , S. Ettori , S. Paltani

The observed flaring of HI disk in the outer region of galaxies has been used in the past to determine the shape of the dark matter halo. Previous studies based on this concept suggest a slightly oblate halo (axis ratio ~ 0.8) for our…

天体物理学 · 物理学 2009-11-11 C. A. Narayan , K. Saha , C. J. Jog

We phenomenologically developed a propagation model of high energy galactic cosmic rays. We derived the analytical solutions by adopting the semi-empirical diffusion equation, proposed by Berezinskii {\it et al.}(1990) and the diffusion…

高能天体物理现象 · 物理学 2012-02-07 Hideyoshi Arakida , Shuichi Kuramata

We investigate if the gamma ray halo, for which recent evidence has been found in EGRET data, can be explained by neutralino annihilations in a clumpy halo. We find that the measured excess gamma ray flux can be explained through a moderate…

天体物理学 · 物理学 2009-10-30 L. Bergstrom , J. Edsjo , P. Ullio

A halo model with heavy relic neutrinos N belonging to a fourth generation and their annihilations in galactic halo may explain the recent evidence of diffused gamma (GeV) radiation around galactic plane. We considered a neutrino mass in…

天体物理学 · 物理学 2007-05-23 D. Fargion , R. Konoplich , M. Grossi , M. Khlopov

We performed GMRT low frequency observations of the radio halos, relics and new candidates belonging to the GMRT Radio Halo Cluster Sample first observed at 610 MHz. High sensitivity imaging was performed using the GMRT at 325 MHz and 240…

A shock-accelerated particle flux \propto p^-s, where p is the particle momentum, follows from simple theoretical considerations of cosmic-ray acceleration at nonrelativistic shocks followed by rigidity-dependent escape into the Galactic…

高能天体物理现象 · 物理学 2015-06-05 Charles D. Dermer

The optical properties of the second generation dust that we observe in debris disks remain quite elusive, whether it is the absorption efficiencies at millimeter wavelengths or the (un)polarized phase function at near-infrared wavelengths.…

地球与行星天体物理 · 物理学 2022-08-24 Johan Olofsson , Philippe Thébault , Grant M. Kennedy , Amelia Bayo

Diffuse gamma-ray emission (DGE) has been discovered over the Galactic disk in the energy range from sub-GeV to sub-PeV. While it is believed to be dominated by the pionic emission of cosmic ray (CR) hadrons via interactions with…

高能天体物理现象 · 物理学 2023-05-18 Kai Yan , Ruo-Yu Liu

The particle diffusion coefficients of three TeV pulsar halos observed so far are inferred to be significantly smaller than the typical value of the interstellar medium (ISM). The anisotropic diffusion model ascribes the slow diffusion to…

高能天体物理现象 · 物理学 2022-08-24 Kai Yan , Ruo-Yu Liu , S. Z. Chen , Xiang-Yu Wang

Context. Extended gamma-ray TeV emission (TeV halos) around middle-aged pulsars has been detected. A proposed model to explain these TeV halos is that electrons from a degree-wide Pulsar Wind Nebula (PWN) get up-scattered by cosmic…

高能天体物理现象 · 物理学 2023-10-17 A. Khokhriakova , W. Becker , G. Ponti , M. Sasaki , B. Li , R. -Y. Liu

The reflection and transmission of a few-cycle Ti:Sa laser pulse iminging on a thin plasma layer have been analysed on the basis of classical electrodynamics. An approximate analytic solution has been given for the coupled Maxwell-Lorentz…

等离子体物理 · 物理学 2011-11-09 Sandor Varro

The Large High-Altitude Air Shower Observatory (LHAASO) recently published measurements of diffuse Galactic gamma-ray emission (DGE) in the 10-1000 TeV energy range. The measured DGE flux is significantly higher than the expectation from…

高能天体物理现象 · 物理学 2024-08-27 Ensheng Chen , Kun Fang , Xiaojun Bi