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Recent data from cosmic ray experiments such as PAMELA, Fermi, ATIC and PPB-BETS all suggest the need for a new primary source of electrons and positrons at high (>~100 GeV) energies. Many proposals have been put forth to explain these…

高能天体物理现象 · 物理学 2009-11-30 Ilias Cholis , Neal Weiner

The $\Lambda$ cold dark matter ($\Lambda\textrm{CDM}$) model is currently known as the simplest cosmology model that best describes observations with minimal number of parameters. Here we introduce a cosmology model that is preferred over…

宇宙学与河外天体物理 · 物理学 2015-03-05 Chan-Gyung Park

The nature of dark matter (DM) is still debated. While cold DM (CDM) is the standard paradigm, warm DM (WDM) may ease some small-scale tensions in the $\Lambda$CDM framework. Line-intensity mapping (LIM) offers a novel probe of DM…

宇宙学与河外天体物理 · 物理学 2026-03-17 Elena Marcuzzo , Cristiano Porciani , Emilio Romano-Díaz , Azadeh Moradinezhad Dizgah , Prachi Khatri , Matteo Viel

It has been claimed that the standard model of cosmology (LCDM) cannot easily account for a number of observations on relatively small scales, motivating extensions to the standard model. Here we introduce a new suite of cosmological…

宇宙学与河外天体物理 · 物理学 2020-08-12 Sam G. Stafford , Shaun T. Brown , Ian G. McCarthy , Andreea S. Font , Andrew Robertson , Robert Poole-Mckenzie

We present logistic dark energy model (LDEM), where the dark energy density follows a logistic function for the scale factor. The equation of state parameter of dark energy ($w_D$) transitioned from $-1$ in the distant past to its current…

宇宙学与河外天体物理 · 物理学 2024-06-27 Sarath Nelleri , Gopi Krishna , Navaneeth Poonthottathil

Isocurvature fluctuations can be generated in various scenarios in the early Universe. In particular, some specific models predict those with a blue-tilted spectrum, which is consistent with the constraints from cosmic microwave background…

宇宙学与河外天体物理 · 物理学 2025-08-07 Sai Chaitanya Tadepalli , Tomo Takahashi

We investigate the diversity of dark matter (DM) density profiles in a large sample of late-type galaxies from the SPARC database, with the goal of testing whether a cusp-to-core transition occurs across galaxy mass scales. We perform…

星系天体物理 · 物理学 2026-01-27 Kohei Hayashi , Yuka Kaneda , Masao Mori , Michi Shinozaki

The canonical cosmological constant dominated cold dark matter model (LCDM) may possess too much power on small scales at z=0, manifested as central over-concentration of dark matter and over-abundance of dwarf galaxies. We suggest an…

天体物理学 · 物理学 2009-10-31 Renyue Cen

We present two matched sets of five simulations each, covering five presently favored simple modifications to the standard cold dark matter (CDM) scenario. One simulation suite, with a linear box size of 75 Mpc/h, is designed for high…

天体物理学 · 物理学 2009-10-30 Michael A. K. Gross , Rachel S. Somerville , Joel R. Primack , Jon Holtzman , Anatoly Klypin

The small-scale crisis, discrepancies between observations and N-body simulations, may imply suppressed matter fluctuations on subgalactic distance scales. Such a suppression could be caused by some early-universe mechanism (e.g., broken…

宇宙学与河外天体物理 · 物理学 2017-07-05 Tomohiro Nakama , Jens Chluba , Marc Kamionkowski

Cross-correlating the lensing signals of galaxies and comic microwave background (CMB) fluctuations is expected to provide valuable cosmological information. In particular it may help tighten constraints on parameters describing the…

宇宙学与河外天体物理 · 物理学 2017-09-14 Philipp M. Merkel , Bjoern Malte Schaefer

The Cold Dark Matter (CDM) theory predicts a wealth of substructure within dark halos. These predictions match observations of galaxy clusters like the nearby Virgo cluster. However, CDM has a "small scale crisis" since galaxies dominate…

天体物理学 · 物理学 2009-11-10 Elena D'Onghia , George Lake

In the cold dark matter (CDM) picture of structure formation, galaxy mass distributions are predicted to have a considerable amount of structure on small scales. Strong gravitational lensing has proven to be a useful tool for studying this…

Direct detection of Weakly Interacting Massive Particle (WIMP) candidates of Dark Matter (DM) is studied within the context of a self-consistent truncated isothermal model of the finite-size dark halo of the Galaxy based on the "King model"…

宇宙学与河外天体物理 · 物理学 2014-01-03 Soumini Chaudhury , Pijushpani Bhattacharjee , Ramanath Cowsik

The fluid forces associated with primordial magnetic fields (PMFs) generate small-scale fluctuations in the primordial density field, which add to the $\mathrm{\Lambda CDM}$ linear matter power spectrum on small scales. These enhanced…

宇宙学与河外天体物理 · 物理学 2024-04-01 Hector Afonso G. Cruz , Tal Adi , Jordan Flitter , Marc Kamionkowski , Ely D. Kovetz

Cosmic background neutrinos have a large velocity dispersion, which causes the evolution of long-wavelength density perturbations to depend on scale. This scale-dependent growth leads to the well-known suppression in the linear theory…

宇宙学与河外天体物理 · 物理学 2018-06-27 Chi-Ting Chiang , Wayne Hu , Yin Li , Marilena LoVerde

Using a semianalytic code, we show how baryon physics in a $\Lambda$CDM cosmology could solve the discrepancy between numerical predictions of dark matter haloes and observations, ranging from dwarf galaxies to clusters, without the need of…

星系天体物理 · 物理学 2018-09-28 Antonino Del Popolo , Francesco Pace , Morgan Le Delliou , Xiguo Lee

The recent BICEP2 detection of degree scale CMB B-mode polarization, coupled with a deficit of observed power in large angle temperature anisotropy, suggest that the slow-roll parameter $\epsilon_H$, the fractional variation in the Hubble…

宇宙学与河外天体物理 · 物理学 2014-06-11 Wayne Hu

A sudden small change in the second derivative of the inflaton potential can result in a universal local feature in the spectrum of primordial perturbations generated during inflation. The exact solution describing this feature \cite{minu}…

天体物理学 · 物理学 2009-07-22 Minu Joy , Arman Shafieloo , Varun Sahni , Alexei A. Starobinsky

We use statistical inference theory to explore the constraints from future galaxy weak lensing (cosmic shear) surveys combined with the current CMB constraints on cosmological parameters, focusing particularly on the running of the spectral…

天体物理学 · 物理学 2009-11-10 Mustapha Ishak , Christopher M. Hirata , Patrick McDonald , Uros Seljak