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Related papers: Using Perturbative Least Action to Reconstruct the…

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Local Group galaxies such as the Milky Way, the Magellanic Clouds, and M31 are being used by a number of international collaborations to search for microlensing events. Type and number of detections place constraints on dark matter and the…

Astrophysics · Physics 2007-05-23 Eva K. Grebel

The mass of the Local Group (LG), comprising the Milky Way (MW), Andromeda (M31), and their satellites, is crucial for validating galaxy formation and cosmological models. Traditional virial mass estimates, which rely on line-of-sight (LoS)…

Astrophysics of Galaxies · Physics 2025-06-04 David Benisty , David Mota

Key and still largely missing parameters for measuring the mass content and distribution of the Local Group are the proper motion vectors of its member galaxies. The problem when trying to derive the gravitational potential of the Local…

Astrophysics · Physics 2007-05-23 A. Brunthaler , M. Reid , H. Falcke , L. J. Greenhill , C. Henkel

We combine the equations of motion that govern the dynamics of galaxies in the local volume with Bayesian techniques in order to fit orbits to published distances and velocities of galaxies within $\sim 3$ Mpc. We find a Local Group (LG)…

Astrophysics of Galaxies · Physics 2015-06-19 Jorge Peñarrubia , Yin-Zhe Ma , Matthew G. Walker , Alan McConnachie

The classic model of the Local Group (LG) is that of two dominant constituents, the Milky Way and M31, first separating and then detaching from the Hubble flow, leading to a nearly radial approaching orbit. This simple model has been…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-26 Louis E. Strigari

Galaxy groups are essential for studying the distribution of matter on a large scale in redshift surveys and for deciphering the link between galaxy traits and their associated halos. In this work, we propose a widely applicable method for…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-03 Juntao Ma , Jie Wang , Tianxiang Mao , Hongxiang Chen , Yuxi Meng , Xiaohu Yang , Qingyang Li

Strong gravitationally lensed arcs produced by galaxy clusters have been observationally detected for several decades now. These strong lensing constraints provided high-fidelity mass models for cluster lenses that include substructure down…

Astrophysics of Galaxies · Physics 2024-03-18 Atınç Çağan Şengül , Simon Birrer , Priyamvada Natarajan , Cora Dvorkin

The measurement of cosmological parameters is investigated in a representation of the least-action method that uses a redshift-space dataset to simultaneously constrain the real-space fields $\delta$,$\b v$. This method is robust in…

Astrophysics · Physics 2009-10-31 Mikel Susperregi

In this report, we present a new method for reconstructing N body initial conditions from a proscribed final density field. This method, Perturbative Least Action (PLA) is similar to traditional least action approaches, except that orbits…

Astrophysics · Physics 2007-05-23 D. M. Goldberg , D. N. Spergel

We use recent proper motion measurements of the tangential velocity of M31, along with its radial velocity and distance, to derive the likelihood of the sum of halo masses of the Milky Way and M31. This is done using a sample halo pairs in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Roberto E. Gonzalez , Andrey V. Kravtsov , Nickolay Y. Gnedin

We introduce "Simulations Beyond The Local Universe" (SIBELIUS) that connect the Local Group to its cosmic environment. We show that introducing hierarchical small-scale perturbations to a density field constrained on large scales by…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-24 Till Sawala , Stuart McAlpine , Jens Jasche , Guilhem Lavaux , Adrian Jenkins , Peter H. Johansson , Carlos S. Frenk

We assess the performance of a perturbation theory inspired method for inferring cosmological parameters from the joint measurements of galaxy-galaxy weak lensing ($\Delta\Sigma$) and the projected galaxy clustering ($w_{\rm p}$). To do…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-21 Sunao Sugiyama , Masahiro Takada , Yosuke Kobayashi , Hironao Miyatake , Masato Shirasaki , Takahiro Nishimichi , Youngsoo Park

We revisit the estimation of the combined mass of the Milky Way and Andromeda (M31), which dominate the mass of the Local Group. We make use of an ensemble of 30,190 halo pairs from the Small MultiDark simulation, assuming a $\Lambda$CDM…

Astrophysics of Galaxies · Physics 2017-12-27 Michael McLeod , Noam Libeskind , Ofer Lahav , Yehuda Hoffman

We use Density Estimation Likelihood-Free Inference, $\Lambda$ Cold Dark Matter simulations of $\sim 2M$ galaxy pairs, and data from Gaia and the Hubble Space Telescope to infer the sum of the masses of the Milky Way and Andromeda (M31)…

Astrophysics of Galaxies · Physics 2021-01-20 Pablo Lemos , Niall Jeffrey , Lorne Whiteway , Ofer Lahav , Niam I Libeskind , Yehuda Hoffman

Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Rachel Mandelbaum , Uros Seljak , Tobias Baldauf , Robert E. Smith

Our Local Group, dominated in mass by the Milky Way (MW) and M31, provides a unique laboratory for testing $\Lambda$CDM cosmology on small scales owing to its proximity. However, its connection to the surrounding large-scale environment,…

Astrophysics of Galaxies · Physics 2026-01-14 Kai Wang , Peder Norberg , Azadeh Fattahi , Louis E. Strigari

We compare the properties of galaxy groups extracted from the Updated Zwicky Catalogue (UZC) with those of groups extracted from N-body simulations of the local Universe, in a LambdaCDM and a tauCDM cosmology. In the simulations, the…

Astrophysics · Physics 2009-11-11 L. Casagrande , A. Diaferio

The positions and velocities of galaxies in the Local Group (LG) measure the gravitational field within it. This is mostly due to the Milky Way (MW) and Andromeda (M31). We constrain their masses using distance and radial velocity (RV)…

Astrophysics of Galaxies · Physics 2026-05-12 Indranil Banik , Hongsheng Zhao

Galaxy clusters are one of the most powerful probes to study extensions of General Relativity and the Standard Cosmological Model. Upcoming surveys like the Vera Rubin Observatory's Legacy Survey of Space and Time are expected to…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-19 Markus Michael Rau , Florian Kéruzoré , Nesar Ramachandra , Lindsey Bleem

Our Galaxy, Andromeda and their companion dwarf galaxies form the Local Group. Most of the mass in and around it is believed to be dark matter rather than gas or stars, so its distribution must be inferred from the effect of gravity on the…

Astrophysics of Galaxies · Physics 2026-01-27 Ewoud Wempe , Simon D. M. White , Amina Helmi , Guilhem Lavaux , Jens Jasche