scholarly journals ATLAS probe: Breakthrough science of galaxy evolution, cosmology, Milky Way, and the Solar System

2019 ◽  
Vol 36 ◽  
Author(s):  
Yun Wang ◽  
Massimo Robberto ◽  
Mark Dickinson ◽  
Lynne A. Hillenbrand ◽  
Wesley Fraser ◽  
...  
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Galaxy Evolution ◽  
Milky Way ◽  
Space Mission ◽  
Field Of View ◽  
Wide Field ◽  
Large Area

AbstractAstrophysics Telescope for Large Area Spectroscopy Probe is a concept for a National Aeronautics and Space Administration probe-class space mission that will achieve ground-breaking science in the fields of galaxy evolution, cosmology, Milky Way, and the Solar System. It is the follow-up space mission to Wide Field Infrared Survey Telescope (WFIRST), boosting its scientific return by obtaining deep 1–4 μm slit spectroscopy for ∼70% of all galaxies imaged by the ∼2 000 deg2WFIRST High Latitude Survey atz> 0.5. Astrophysics Telescope for Large Area Spectroscopy will measure accurate and precise redshifts for ∼200 M galaxies out toz< 7, and deliver spectra that enable a wide range of diagnostic studies of the physical properties of galaxies over most of cosmic history. Astrophysics Telescope for Large Area Spectroscopy Probe and WFIRST together will produce a 3D map of the Universe over 2 000 deg2, the definitive data sets for studying galaxy evolution, probing dark matter, dark energy and modifications of General Relativity, and quantifying the 3D structure and stellar content of the Milky Way. Astrophysics Telescope for Large Area Spectroscopy Probe science spans four broad categories: (1) Revolutionising galaxy evolution studies by tracing the relation between galaxies and dark matter from galaxy groups to cosmic voids and filaments, from the epoch of reionisation through the peak era of galaxy assembly; (2) Opening a new window into the dark Universe by weighing the dark matter filaments using 3D weak lensing with spectroscopic redshifts, and obtaining definitive measurements of dark energy and modification of General Relativity using galaxy clustering; (3) Probing the Milky Way’s dust-enshrouded regions, reaching the far side of our Galaxy; and (4) Exploring the formation history of the outer Solar System by characterising Kuiper Belt Objects. Astrophysics Telescope for Large Area Spectroscopy Probe is a 1.5 m telescope with a field of view of 0.4 deg2, and uses digital micro-mirror devices as slit selectors. It has a spectroscopic resolution ofR= 1 000, and a wavelength range of 1–4 μm. The lack of slit spectroscopy from space over a wide field of view is the obvious gap in current and planned future space missions; Astrophysics Telescope for Large Area Spectroscopy fills this big gap with an unprecedented spectroscopic capability based on digital micro-mirror devices (with an estimated spectroscopic multiplex factor greater than 5 000). Astrophysics Telescope for Large Area Spectroscopy is designed to fit within the National Aeronautics and Space Administration probe-class space mission cost envelope; it has a single instrument, a telescope aperture that allows for a lighter launch vehicle, and mature technology (we have identified a path for digital micro-mirror devices to reach Technology Readiness Level 6 within 2 yr). Astrophysics Telescope for Large Area Spectroscopy Probe will lead to transformative science over the entire range of astrophysics: from galaxy evolution to the dark Universe, from Solar System objects to the dusty regions of the Milky Way.

scholarly journals LONG RANGE GRAVITY TESTS AND THE PIONEER ANOMALY

2007 ◽  
Vol 16 (12a) ◽  
pp. 2091-2105 ◽  
Author(s):  
SERGE REYNAUD ◽  
MARC-THIERRY JAEKEL
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Equivalence Principle ◽  
Experimental Tests ◽  
Pioneer Anomaly ◽  
New Space ◽  
Tests Of Gravity ◽  
Good Agreement

Experimental tests of gravity performed in the solar system show a good agreement with general relativity. The latter is, however, challenged by the Pioneer anomaly, which might be pointing at some modification of gravity law at ranges of the order of the size of the solar system. As this question could be related to the puzzles of "dark matter" or "dark energy," it is important to test it with care. There exist metric extensions of general relativity which preserve the well-verified equivalence principle while possibly changing the metric solution in the solar system. Such extensions have the capability to preserve compatibility with existing gravity tests while opening free space for the Pioneer anomaly. They constitute arguments for new mission designs and new space technologies as well as for having a new look at data of already-performed experiments.

scholarly journals The local dark sector

2021 ◽  
Author(s):  
Joel Bergé ◽  
Laura Baudis ◽  
Philippe Brax ◽  
Sheng-Wey Chiow ◽  
Bruno Christophe ◽  
...  
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Gravitational Potential ◽  
Atomic Clock ◽  
Dark Sector ◽  
New Knowledge ◽  
Near Future

AbstractWe speculate on the development and availability of new innovative propulsion techniques in the 2040s, that will allow us to fly a spacecraft outside the Solar System (at 150 AU and more) in a reasonable amount of time, in order to directly probe our (gravitational) Solar System neighborhood and answer pressing questions regarding the dark sector (dark energy and dark matter). We identify two closely related main science goals, as well as secondary objectives that could be fulfilled by a mission dedicated to probing the local dark sector: (i) begin the exploration of gravitation’s low-acceleration regime with a spacecraft and (ii) improve our knowledge of the local dark matter and baryon densities. Those questions can be answered by directly measuring the gravitational potential with an atomic clock on-board a spacecraft on an outbound Solar System orbit, and by comparing the spacecraft’s trajectory with that predicted by General Relativity through the combination of ranging data and the in-situ measurement (and correction) of non-gravitational accelerations with an on-board accelerometer. Despite a wealth of new experiments getting online in the near future, that will bring new knowledge about the dark sector, it is very unlikely that those science questions will be closed in the next two decades. More importantly, it is likely that it will be even more urgent than currently to answer them. Tracking a spacecraft carrying a clock and an accelerometer as it leaves the Solar System may well be the easiest and fastest way to directly probe our dark environment.

scholarly journals LSST and the Epoch of Reionization Experiments

2017 ◽  
Vol 12 (S333) ◽  
pp. 222-227
Author(s):  
Željko Ivezić
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Time Domain ◽  
Point Sources ◽  
Field Of View ◽  
Next Generation ◽  
Imaging Data ◽  
Primary Mirror ◽  
Scientific Investigations ◽  
Near Earth Asteroids

AbstractThe Large Synoptic Survey Telescope (LSST), a next generation astronomical survey, sited on Cerro Pachon in Chile, will provide an unprecedented amount of imaging data for studies of the faint optical sky. The LSST system includes an 8.4m (6.7m effective) primary mirror and a 3.2 Gigapixel camera with a 9.6 sq. deg. field of view. This system will enable about 10,000 sq. deg. of sky to be covered twice per night, every three to four nights on average, with typical 5-sigma depth for point sources ofr= 24.5 (AB). With over 800 observations in theugrizybands over a 10-year period, these data will enable coadded images reachingr= 27.5 (about 5 magnitudes deeper than SDSS) as well as studies of faint time-domain astronomy. The measured properties of newly discovered and known astrometric and photometric transients will be publicly reported within 60 sec after closing the shutter. The resulting hundreds of petabytes of imaging data for about 40 billion objects will be used for scientific investigations ranging from the properties of near-Earth asteroids to characterizations of dark matter and dark energy. For example, simulations estimate that LSST will discover about 1,000 quasars at redshifts exceeding 7; this sample will place tight constraints on the cosmic environment at the end of the reionization epoch. In addition to a brief introduction to LSST, I review the value of LSST data in support of epoch of reionization experiments and discuss how international participants can join LSST.

scholarly journals In Pursuit of the Least Luminous Galaxies

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Beth Willman
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Field Survey ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Wide Field ◽  
Dark Matter Halos ◽  
The Past ◽  
Luminous Galaxies ◽  
Host Stars

The dwarf galaxy companions to the Milky Way are unique cosmological laboratories. With luminosities as low as10−7LMW, they inhabit the lowest mass dark matter halos known to host stars and are presently the most direct tracers of the distribution, mass spectrum, and clustering scale of dark matter. Their resolved stellar populations also facilitate detailed studies of their history and mass content. To fully exploit this potential requires a well-defined census of virtually invisible galaxies to the faintest possible limits and to the largest possible distances. I review the past and present impacts of survey astronomy on the census of Milky Way dwarf galaxy companions and discuss the future of finding ultra-faint dwarf galaxies around the Milky Way and beyond in wide-field survey data.

scholarly journals Gravitoelectromagnetism and stellar orbits in galaxies

2021 ◽  
pp. 2150102
Author(s):  
Viktor T. Toth
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Gravitational Field ◽  
Magnetic Force ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Observable Effect ◽  
Stellar Orbits ◽  
Gravitational Fields ◽  
The Impact

Beyond the Newtonian approximation, gravitational fields in general relativity can be described using a formalism known as gravitoelectromagnetism. In this formalism, a vector potential, the gravitomagnetic potential, arises as a result of moving masses, in strong analogy with the magnetic force due to moving charges in Maxwell’s theory. Gravitomagnetism can affect orbits in the gravitational field of a massive, rotating body. This raises the possibility that gravitomagnetism may serve as the dominant physics behind the anomalous rotation curves of spiral galaxies, eliminating the need for dark matter. In this essay, we methodically work out the magnitude of the gravitomagnetic equivalent of the Lorentz force and apply the result to the Milky Way. We find that the resulting contribution is too small to produce an observable effect on these orbits. We also investigate the impact of cosmological boundary conditions on the result and find that these, too, are negligible.

scholarly journals Entropic Information Theory: Formulae and Quantum Gravity, Bits from bit

2021 ◽  
Author(s):  
olivier denis
Keyword(s):  
Information Theory ◽  
General Relativity ◽  
Dark Matter ◽  
Quantum Mechanics ◽  
Dark Energy ◽  
Quantum Gravity ◽  
Planck Scale ◽  
Basic Structure ◽  
Mathematical Framework ◽  
Information Framework

We show here that entropic information is capable of unifying all aspects of the universe at all scales in a coherent and global theoretical mathematical framework materialized by entropic information framework, theory and formulas, where dark matter, dark energy and gravity are truly informationals processes and where information is code and code is what creates the process, it is itself the process. Mass, energy and movement of information are respectively dark matter, dark energy, and gravity. Here, we reconcile general relativity and quantum mechanics by introducing quantum gravity for the Planckian scale. The formulas of entropic information are expressed in natural units, physical units of measurement based only on universal constants, constants, which refer to the basic structure of the laws of physics: C and G are part of the structure of space-time in general relativity, and h captures the relationship between energy and frequency that is the basis of quantum mechanics. Here we show that entropic information formulas are able to present entropic information in various unifying aspects and introduce gravity at the Planck scale. We prove that Entropic information theory is thus building the bridge between general relativity and quantum mechanics

Orbits

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Milky Way ◽  
Extrasolar Planets ◽  
Binary Star ◽  
Milky Way Galaxy ◽  
Newtonian Model ◽  
Theory Of Gravity ◽  
The Masses ◽  
The Universe

Orbits are ubiquitous in the universe: moons orbit planets, planets orbit stars, stars orbit around the center of the Milky Way galaxy, and so on. Any theory of gravity will have to explain the properties of all these orbits. To pave the way for developing the metric theory of gravity (general relativity) this chapter examines the basics of orbits as observed and as explained by the Newtonian model of gravity. We can use our understanding of gravity to infer the masses and other properties of these cosmic systems. Te chapter concludes with four optional sections in this spirit, covering the slingshot maneuver; dark matter; binary star orbits and how they reveal the masses of stars; and extrasolar planets.

scholarly journals Galactic Archeology with 4MOST

2017 ◽  
Vol 13 (S334) ◽  
pp. 225-232 ◽  
Author(s):  
S. Feltzing ◽  
T. Bensby ◽  
M. Bergemann ◽  
C. Chiappini ◽  
N. Christlieb ◽  
...  
Keyword(s):  
Milky Way ◽  
Galactic Halo ◽  
Near Field ◽  
Field Of View ◽  
Wide Field

Abstract4MOST is a new wide-field, high-multiplex spectroscopic survey facility for the VISTA telescope of ESO. Starting in 2022, 4MOST will deploy 2400 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. In this contribution we give an outline of the major science goals we wish to achieve with 4MOST in the area of Galactic Archeology. The 4MOST Galactic Archeology surveys have been designed to address long-standing and far-reaching problems in Galactic science. They are focused on four major themes: 1) Near-field cosmology tests, 2) Chemo-dynamical characterisation of the major Milky Way stellar components, 3) The Galactic Halo and beyond, and 4) Discovery and characterisation of extremely metal-poor stars. In addition to a top-level description of the Galactic surveys we provide information about how the community will be able to join 4MOST via a call for Public Spectroscopic Surveys that ESO will launch.

scholarly journals Observing the Dark Sector

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 137
Author(s):  
Valerio Marra ◽  
Rogerio Rosenfeld ◽  
Riccardo Sturani
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Standard Model ◽  
Dark Sector ◽  
The Standard Model

Despite the observational success of the standard model of cosmology, present-day observations do not tightly constrain the nature of dark matter and dark energy and modifications to the theory of general relativity. Here, we will discuss some of the ongoing and upcoming surveys that will revolutionize our understanding of the dark sector.

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