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The horizon-scale images of black holes obtained with the Event Horizon Telescope have provided new probes of their metrics and tests of General Relativity. The images are characterized by a bright, near circular ring from the…

High Energy Astrophysical Phenomena · Physics 2022-12-28 Feryal Ozel , Dimitrios Psaltis , Ziri Younsi

We extend the formalism of the relativistic thermal and kinematic Sunyaev-Zel'dovich effects and include the polarization of the cosmic microwave background photons. We consider the situation that a cluster of galaxies is moving with a…

Astrophysics · Physics 2015-06-24 Naoki Itoh , Satoshi Nozawa , Yasuharu Kohyama

The motion of our solar system relative to the CMB rest frame leads to subtle distortions in the observed CMB sky map due to the aberration effect. Usually the corresponding peculiar velocity is determined from the CMB dipole but neglecting…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-30 Ralf Aurich , David Reinhardt

The inhomogeneous distribution of matter in the non-linear regime of galaxies, clusters of galaxies and voids is described by an exact, spherically symmetric inhomogeneous solution of Einstein's gravitational field equations, corresponding…

Astrophysics · Physics 2009-11-11 J. W. Moffat

Taking into account a torsion field gives rise to a negative pressure contribution in cosmological dynamics and then to an accelerated behaviour of Hubble fluid. The presence of torsion has the same effect of a Lambda - term. We obtain a…

Astrophysics · Physics 2009-11-07 S. Capozziello , V. F. Cardone , E. Piedipalumbo , M. Sereno , A. Troisi

We study line driven stellar winds using time-dependent radiation hydrodynamics where the continuum radiation couples to the gas via either a scattering or absorption opacity and there is an additional radiation force due to spectral lines…

Solar and Stellar Astrophysics · Physics 2023-11-30 Sergei Dyda , Shane W. Davis

We present a novel test of the cosmological principle: the idea that, on sufficiently large scales, the universe should appear homogeneous and isotropic to observers comoving with the Hubble flow. This is a fundamental assumption in modern…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-19 Oliver T. Oayda , Geraint F. Lewis

We perform statistical analyses of the infall of dark-matter onto clusters in numerical simulations within the concordance LCDM model. By studying the infall profile around clusters of different mass, we find a linear relation between the…

Astrophysics · Physics 2009-11-11 Maximiliano C. Pivato , Nelson D. Padilla , Diego G. Lambas

Recently we showed that in FLRW cosmology, the contribution from higher curvature terms in any generic metric gravity theory to the energy-momentum tensor is of the perfect fluid form. Such a geometric perfect fluid can be interpreted as a…

General Relativity and Quantum Cosmology · Physics 2024-08-07 Metin Gürses , Yaghoub Heydarzade , Çetin Şentürk

Our local environment at $r<10$ Mpc expands linearly and smoothly, as if ruled by a uniform matter distribution, while observations show the very clumpy local universe. This is a long standing enigma in cosmology. We argue that the recently…

Astrophysics · Physics 2009-10-31 Yurij Baryshev , Arthur Chernin , Pekka Teerikorpi

We analyze the peculiar velocity field for 2400 flat spiral galaxies selected from an infrared sky survey (2MFGC). The distances to the galaxies have been determined from the Tully-Fisher relation in the photometric J band with a dispersion…

The detailed nature of dark energy remains a mystery, leaving the possibility that its effects might be explained by changes to the laws of gravity on large scales. The peculiar velocities of galaxies directly trace the strength of gravity…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-29 Stuart Lyall , Chris Blake , Ryan J. Turner

I provide a model rotation curve for the Milky Way that matches the details of the terminal velocity curve normalized to the Galactocentric distance $R_0 = 8.122$ kpc obtained by the GRAVITY collaboration and the corresponding circular…

Astrophysics of Galaxies · Physics 2018-08-29 Stacy McGaugh

We have obtained new Tully-Fisher (TF) peculiar velocity measurements for 52 Abell galaxy clusters distributed throughout the sky between ~ 50 and 200 Mpc/h.The measurements are based on I band photometry and optical rotation curves for a…

Galactic rotation curves are often considered the first robust evidence for the existence of dark matter. However, even in the presence of a dark matter halo, other galactic-scale observations, such as the Baryonic Tully-Fisher Relation and…

Astrophysics of Galaxies · Physics 2019-10-23 Mariangela Lisanti , Matthew Moschella , Nadav Joseph Outmezguine , Oren Slone

We explore the kinematics (both the radial velocity and the proper motion) of the vertical X-shaped feature in the Milky Way with an N-body bar/bulge model. From the solar perspective, the distance distribution of particles is double-peaked…

Astrophysics of Galaxies · Physics 2015-08-06 Yujing Qin , Juntai Shen , Zhao-Yu Li , Shude Mao , Martin C. Smith , R. Michael Rich , Andrea Kunder , Chao Liu

In this Letter we construct the Hubble diagram for a Universe where dark matter is universally charged under a dark non-linear electromagnetic force which features a screening mechanism of the K-mouflage type for repulsive forces. By…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-07 Jose Beltran Jimenez , Dario Bettoni , Philippe Brax

Many problems in machine learning can be formulated as optimizing a convex functional over a vector space of measures. This paper studies the convergence of the mirror descent algorithm in this infinite-dimensional setting. Defining Bregman…

Optimization and Control · Mathematics 2022-10-12 Pierre-Cyril Aubin-Frankowski , Anna Korba , Flavien Léger

Cosmic acceleration is widely believed to require either a source of negative pressure (i.e., dark energy), or a modification of gravity, which necessarily implies new degrees of freedom beyond those of Einstein gravity. In this paper we…

High Energy Physics - Theory · Physics 2017-06-28 Lasha Berezhiani , Justin Khoury , Junpu Wang

Late time cosmic acceleration may be achieved by modifying gravity on large scales. This should also have consequences on the evolution of perturbations. We thus extend our study of exponential infrared $f(T)$ teleparallel gravity to…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-11 Mahmoud Hashim , Amr A. El-Zant , Waleed El Hanafy , Alexey Golovnev