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Strong gravitational lensing by galaxies provides us with a unique opportunity to understand the nature of gravity on galactic and extra-galactic scales. In this paper, we propose a new multimessenger approach using data from both…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-08 Tao Yang , Bin Hu , Rong-Gen Cai , Bin Wang

We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I LRIS and Keck II DEIMOS spectrographs. Based on their g-i colors (taken with the…

The works in this portfolio test the hypothesis that it is not possible to extrapolate the Newtonian inverse square law of gravity from Solar System to galaxy scales. In particular, I look into various tests of Modified Newtonian Dynamics…

Astrophysics of Galaxies · Physics 2023-09-26 Indranil Banik

The history of the Milky Way Galaxy is written in the properties of its stellar populations. Here we analyse stars observed as part of surveys of local dwarf spheroidal galaxies, but which from their kinematics are highly probable to be…

Fifth forces are ubiquitous in modified gravity theories, and must be screened to evade stringent local tests. This can introduce unusual behaviour in galaxy phenomenology by affecting galaxies' components differently. Here we use the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-18 Ricardo G. Landim , Harry Desmond , Kazuya Koyama , Samantha Penny

Our aim is to provide as clean and as complete a sample as possible of red giant branch stars that are members of the Hercules dSph galaxy. With this sample we explore the velocity dispersion and the metallicity of the system. Stromgren…

Scalar Tensor Vector Gravity(STVG) is a fully covariant Lorentz invariant alternative theory of gravity also called as MOdified Gravity(MOG) which modifies General Relativity(GR) with dynamical massive vector field and scalar fields. In…

General Relativity and Quantum Cosmology · Physics 2022-04-13 Sreekanth Harikumar , Marek Biesiada

The relation of central black hole mass and stellar spheroid velocity dispersion (the M-$\sigma$ relation) is one of the best-known and tightest correlations linking black holes and their host galaxies. There has been much scrutiny…

It has been suggested that the internal dynamics of dwarf spheroidal galaxies (dSphs) can be used to test whether or not ultralight axions with $m_a\sim 10^{-22}\text{eV}$ are a preferred dark matter candidate. However, comparisons to…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-22 Alma X. Gonzalez-Morales , David J. E. Marsh , Jorge Peñarrubia , L. Arturo Ureña-López

Prompted by the recent successful predictions of the internal dynamics of Andromeda's satellite galaxies (McGaugh & Milgrom 2013a,b), we revisit the classical Milky Way dwarf spheroidal satellites Draco, Sculptor, Sextans, Carina, and…

Astrophysics of Galaxies · Physics 2014-05-05 Fabian Lüghausen , Benoit Famaey , Pavel Kroupa

I consider a sample of eight pressure-supported low-surface brightness galaxies in terms of Milgrom's modified Newtonian dynamics (MOND). These objects include seven nearby dwarf spheroidal galaxies -- Sextans, Carina, Leo II, Sculptor,…

Astrophysics of Galaxies · Physics 2021-08-31 R. H. Sanders

The Initial Mass Function (IMF) for massive galaxies can be constrained by combining stellar dynamics with strong gravitational lensing. However, this method is limited by degeneracies between the density profile of dark matter and the…

Dwarf galaxies have been extensively studied in the Local Group, in nearby groups, and selected clusters, giving us a robust picture of their global stellar and dynamical properties in particular locations in the Universe. Intense study of…

The Milky Way (MW) dwarf spheroidal satellite galaxies (dSphs) are particularly intriguing targets to search for gamma rays from Weakly Interacting Massive Particle (WIMP) dark matter (DM) annihilation or decay. They are nearby,…

High Energy Astrophysical Phenomena · Physics 2023-11-10 Alex McDaniel , Marco Ajello , Christopher M. Karwin , Mattia Di Mauro , Alex Drlica-Wagner , Miguel A. Sanchez-Conde

Recent spectroscopic and photometric surveys are providing a comprehensive view of the MW bulge stellar population properties with unprecedented accuracy. This in turn allows us to explore the correlation between kinematics and stellar…

The observed anti-correlation between the central dark matter (DM) densities of the bright Milky Way (MW) dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances poses a potential signature of self-interacting dark matter…

Astrophysics of Galaxies · Physics 2021-03-03 Camila A. Correa

The comparison between dynamical mass and lensing mass provides a targeted test for a wide range of modified gravity models. In our previous paper we showed, through numerical simulations, that the measurement of the line-of-sight velocity…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-05 Tsz Yan Lam , Fabian Schmidt , Takahiro Nishimichi , Masahiro Takada

Using high-resolution N-body simulations we study the stellar properties of dwarf spheroidal galaxies resulting from the tidally induced morphological transformation of disky dwarfs on a cosmologically motivated eccentric orbit around the…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-15 Ewa L. Lokas , Stelios Kazantzidis , Jaroslaw Klimentowski , Lucio Mayer , Simone Callegari

We discover an extended distribution of main-sequence (MS) stars along the minor axis of the Ursa Minor (UMi) dwarf spheroidal galaxy (dSph). This study is enabled by deep, wide Subaru/Hyper Suprime-Cam data, reaching photometric…

The origin of dwarf spheroidal galaxies (dSphs) is investigated in a global cosmological context by simultaneously following the evolution of the Milky Way Galaxy and its dwarf satellites. This approach enable to study the formation of…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Stefania Salvadori