scholarly journals The KBC void and Hubble tension contradict ΛCDM on a Gpc scale − Milgromian dynamics as a possible solution

2020 ◽  
Vol 499 (2) ◽  
pp. 2845-2883 ◽  
Author(s):  
Moritz Haslbauer ◽  
Indranil Banik ◽  
Pavel Kroupa
Keyword(s):  
Local Group ◽  
A Priori ◽  
Model Parameters ◽  
Microwave Background ◽  
Sterile Neutrinos ◽  
Best Fitting ◽  
The Many ◽  
First Time ◽  
The Universe ◽  
Fitting Model

ABSTRACT The KBC void is a local underdensity with the observed relative density contrast δ ≡ 1 − ρ/ρ0 = 0.46 ± 0.06 between 40 and 300 Mpc around the Local Group. If mass is conserved in the Universe, such a void could explain the 5.3σ Hubble tension. However, the MXXL simulation shows that the KBC void causes 6.04σ tension with standard cosmology (ΛCDM). Combined with the Hubble tension, ΛCDM is ruled out at 7.09σ confidence. Consequently, the density and velocity distribution on Gpc scales suggest a long-range modification to gravity. In this context, we consider a cosmological MOND model supplemented with $11 \, \rm {eV}/c^{2}$ sterile neutrinos. We explain why this νHDM model has a nearly standard expansion history, primordial abundances of light elements, and cosmic microwave background (CMB) anisotropies. In MOND, structure growth is self-regulated by external fields from surrounding structures. We constrain our model parameters with the KBC void density profile, the local Hubble and deceleration parameters derived jointly from supernovae at redshifts 0.023−0.15, time delays in strong lensing systems, and the Local Group velocity relative to the CMB. Our best-fitting model simultaneously explains these observables at the $1.14{{\ \rm per\ cent}}$ confidence level (2.53σ tension) if the void is embedded in a time-independent external field of ${0.055 \, a_{_0}}$. Thus, we show for the first time that the KBC void can naturally resolve the Hubble tension in Milgromian dynamics. Given the many successful a priori MOND predictions on galaxy scales that are difficult to reconcile with ΛCDM, Milgromian dynamics supplemented by $11 \, \rm {eV}/c^{2}$ sterile neutrinos may provide a more holistic explanation for astronomical observations across all scales.

scholarly journals The Motion of the Local Group of Galaxies with Respect to the Background of Galaxies

1983 ◽  
Vol 104 ◽  
pp. 255-258
Author(s):  
R. D. Davies
Keyword(s):  
Large Scale ◽  
Local Group ◽  
Microwave Background ◽  
Optical Studies ◽  
Group Motion ◽  
Gravitational Influence ◽  
Nearby Galaxies ◽  
Peculiar Motion ◽  
The Universe ◽  
Hubble Flow

A measurement of the motion of the Local Group of galaxies through the Universe provides an indication of their peculiar motion relative to the Hubble flow consequent upon the gravitational influence of the local large scale mass inhomogeneities. This motion can be measured either relative to the cosmic microwave background at z ∼ 1000 or relative to the background or nearby (z ∼ 0.01) galaxies. The interpretation of published measurements is subject to some uncertainty. As an example, the Local Group motion derived from optical studies of nearby galaxies (Rubin et al. 1976) differs from that derived from radio frequency measurements of the dipole anisotropy in the microwave background. (Boughn et al. 1981, Gorenstein & Smoot 1981).

Data mining-based adaptive regression for developing equilibrium speed–density relationships

2010 ◽  
Vol 37 (3) ◽  
pp. 389-400 ◽  
Author(s):  
Lu Sun ◽  
Jun Yang ◽  
Hani Mahmassani ◽  
Wenjun Gu ◽  
Bum-Jin Kim
Keyword(s):  
Data Mining ◽  
Genetic Algorithm ◽  
Computer Software ◽  
Model Parameters ◽  
Traffic Data ◽  
Traffic Operations ◽  
Density Relation ◽  
Best Fitting ◽  
Adaptive Regression ◽  
Fitting Model

In this paper, we developed a methodological framework to deal with traffic-stream modeling based on data mining, steepest-ascend algorithm, and genetic algorithm. The new method is adaptive in nature and has a greater flexibility and generality compared with existing methods. It provides an optimum overall fitting of the observed data. Specifically, the advantages of adaptive regression are that (1) knot positions and model parameters are estimated optimally and simultaneously using genetic algorithm, and presetting of knot positions can be performed in terms of either density or speed; (2) the method is automatic and data driven, and it will always find out the best fitting model to site-dependent actual traffic data; and (3) the user has a great flexibility to specify the degree-model continuity and to define and add new basis functions that are parsimonious and fit better into the traffic data in some regime of speed–density relation. The proposed method and developed computer software package MiningFlow will be beneficial to traffic operations and traffic simulation.

scholarly journals Distribution of IRAS Galaxies

1987 ◽  
Vol 124 ◽  
pp. 229-245
Author(s):  
Michael Rowan-Robinson
Keyword(s):  
Interstellar Dust ◽  
Local Group ◽  
Big Bang ◽  
Galactic Latitude ◽  
Gravitational Acceleration ◽  
Microwave Background ◽  
High Galactic Latitude ◽  
Galaxy Surveys ◽  
Infrared Wavelengths ◽  
The Universe

Infrared wavelengths are free of several of the problems that plague optical galaxy surveys. At high galactic latitude ≥99% of 60μ sources in the IRAS Point Source Catalog, after deletion of obvious stars, are galaxies. At lower latitudes care has to be taken to avoid confusion with emission from interstellar dust (the ‘cirrus’). IRAS galaxies have been used to determined the direction of the gravitational acceleration acting on the Local Group due to galaxies and clusters within about 200 Mpc. This agrees well with the direction of the microwave background dipole. The density of matter in the universe, distributed like IRAS galaxies, needed to account for the observed velocity of the Local Group, corresponds to Ωo = 1.0 ± 0.2. In the standard hot Big Bang model, 90–95% of this matter would have to be non-baryonic.IRAS galaxies are significantly less clustered than optically selected galaxy samples.

scholarly journals Climatic suitability of the eastern paralysis tick, Ixodes holocyclus, and its likely geographic distribution in the year 2050

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ram K. Raghavan ◽  
Z. Koestel ◽  
R. Ierardi ◽  
A. Townsend Peterson ◽  
Marlon E. Cobos
Keyword(s):  
Spatial Distribution ◽  
Western Australia ◽  
Statistical Significance ◽  
Model Parameters ◽  
Moderate Increase ◽  
Climatic Suitability ◽  
Ixodes Holocyclus ◽  
Best Fitting ◽  
Paralysis Tick ◽  
Fitting Model

AbstractThe eastern paralysis tick, Ixodes holocyclus is one of two ticks that cause potentially fatal tick paralysis in Australia, and yet information on the full extent of its present or potential future spatial distribution is not known. Occurrence data for this tick species collected over the past two decades, and gridded environmental variables at 1 km2 resolution representing climate conditions, were used to derive correlative ecological niche models to predict the current and future potential distribution. Several hundreds of candidate models were constructed with varying combinations of model parameters, and the best-fitting model was chosen based on statistical significance, omission rate, and Akaike Information Criterion (AICc). The best-fitting model matches the currently known distribution but also extends through most of the coastal areas in the south, and up to the Kimbolton peninsula in Western Australia in the north. Highly suitable areas are present around south of Perth, extending towards Albany, Western Australia. Most areas in Tasmania, where the species is not currently present, are also highly suitable. Future spatial distribution of this tick in the year 2050 indicates moderate increase in climatic suitability from the present-day prediction but noticeably also moderate to low loss of climatically suitable areas elsewhere.

scholarly journals The effect of our local motion on the Sandage–Loeb test of the cosmic expansion

2019 ◽  
Vol 72 (1) ◽  
Author(s):  
Takuya Inoue ◽  
Eiichiro Komatsu ◽  
Wako Aoki ◽  
Takeshi Chiba ◽  
Toru Misawa ◽  
...  
Keyword(s):  
Solar System ◽  
Local Group ◽  
Galactic Center ◽  
Large Magellanic Cloud ◽  
Local Motion ◽  
Microwave Background ◽  
Cosmic Expansion ◽  
M 31 ◽  
The Universe

Abstract Redshifts of an astronomical body measured at multiple epochs (e.g., separated by 10 yr) are different due to the cosmic expansion. This so-called Sandage–Loeb test offers a direct measurement of the expansion rate of the Universe. However, acceleration in the motion of the Solar System with respect to the cosmic microwave background also changes redshifts measured at multiple epochs. If not accounted for, it yields a biased cosmological inference. To address this, we calculate the acceleration of the Solar System with respect to the Local Group of galaxies to quantify the change in the measured redshift due to local motion. Our study is motivated by the recent determination of the mass of the Large Magellanic Cloud (LMC), which indicates a significant fraction of the Milky Way mass. We find that the acceleration towards the Galactic Center dominates, which gives a redshift change of 7 cm s−1 in 10 yr, while the accelerations due to the LMC and M 31 cannot be ignored, depending on lines of sight. We create all-sky maps of the expected change in redshift and the corresponding uncertainty, which can be used to correct for this effect.

scholarly journals Time and Polar Motion in Early NASA Spacecraft Navigation

2000 ◽  
Vol 178 ◽  
pp. 215-219
Author(s):  
Paul M. Muller
Keyword(s):  
Orbit Determination ◽  
Polar Motion ◽  
A Priori ◽  
Radio Tracking ◽  
Time Service ◽  
Spacecraft Navigation ◽  
Navigation Computer ◽  
The Many ◽  
Station Location ◽  
First Time

AbstractInclusion of Polar Motion and UT1 data (corrections) is essential to achieving the full accuracy in NASA (and other) spacecraft navigation. Tracking station locations are routinely determined to the meter-level and must be available inertially (on the rotating Earth) to equal accuracy a priori in real-time. This implies knowledge of UT1 to 2.5ms and polar motion to lm (and for practical use for the first time accurately predicted and disseminated to the navigation computer programs). This was essential from 1965 onward as we prepared for Apollo, for Apollo itself, and all subsequent missions. This paper presents the history behind the author’s “discovery” circa 1965 at JPL that UT1 and polar motion were not then included in NASA’s Orbit Determination models and programs; how this omission was being “observed” in station location determinations (and errors) from spacecraft radio tracking data; how it was rectified; the essential nature of these data in precision spacecraft navigation including Apollo; and how this became undoubtedly the highest and most critical application of these data in history. There followed widespread recognition of the many observers present and past who tirelessly and often with little visibility outside of professional astronomy made the necessary observations and calculations. As an historical paper, there is room for a few interesting anecdotes and personalities in NASA, as well as the late and much missed Dr. Markowitz then head of the USNO time service, and his successor Dr. Klock, with both of whom the author had the honor, professional benefit, and great personal pleasure of working during this time.

scholarly journals Spectropolarimetric observations of the CIZA J2242.8+5301 northern radio relic: no evidence of high-frequency steepening

2020 ◽  
Vol 498 (2) ◽  
pp. 1628-1637 ◽  
Author(s):  
F Loi ◽  
M Murgia ◽  
V Vacca ◽  
F Govoni ◽  
A Melis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Power Law ◽  
High Frequency ◽  
Galaxy Cluster ◽  
Very High Frequency ◽  
Best Fitting ◽  
First Time ◽  
Polarization Fraction ◽  
Very High ◽  
Fitting Model

ABSTRACT Observations of radio relics at very high frequency (>10 GHz) can help to understand how particles age and are (re-)accelerated in galaxy cluster outskirts and how magnetic fields are amplified in these environments. In this work, we present new single-dish 18.6 GHz Sardinia Radio Telescope and 14.25 GHz Effelsberg observations of the well-known northern radio relic of CIZA J2242.8+5301. We detected the relic which shows a length of ∼1.8 Mpc and a flux density equal to $S_{14.25\, \mathrm{ GHz}}=(9.5\pm 3.9)\, \mathrm{ mJy}$ and $S_{18.6\, \mathrm{ GHz}}=(7.67\pm 0.90)\, \mathrm{ mJy}$ at 14.25 and 18.6 GHz, respectively. The resulting best-fitting model of the relic spectrum from 145 MHz to 18.6 GHz is a power-law spectrum with spectral index α = 1.12 ± 0.03: no evidence of steepening has been found in the new data presented in this work. For the first time, polarization properties have been derived at 18.6 GHz, revealing an averaged polarization fraction of $\sim\! 40{{\ \rm per\ cent}}$ and a magnetic field aligned with the ’filaments’ or ’sheets’ of the relic.

Unrivalled Influence

2013 ◽  
Author(s):  
Judith Herrin
Keyword(s):  
Political Life ◽  
General Introduction ◽  
Women And Gender ◽  
Mothers And Daughters ◽  
Diverse Range ◽  
Long Span ◽  
Imperial Court ◽  
And Gender ◽  
The Many ◽  
First Time

This book explores the exceptional roles that women played in the vibrant cultural and political life of medieval Byzantium. This book evokes the complex and exotic world of Byzantium's women, from empresses and saints to uneducated rural widows. Drawing on a diverse range of sources, the book sheds light on the importance of marriage in imperial statecraft, the tense coexistence of empresses in the imperial court, and the critical relationships of mothers and daughters. It looks at women's interactions with eunuchs, the in-between gender in Byzantine society, and shows how women defended their rights to hold land. The book describes how women controlled their inheritances, participated in urban crowds demanding the dismissal of corrupt officials, followed the processions of holy icons and relics, and marked religious feasts with liturgical celebrations, market activity, and holiday pleasures. The vivid portraits that emerge here reveal how women exerted an unrivalled influence on the patriarchal society of Byzantium, and remained active participants in the many changes that occurred throughout the empire's millennial history. The book brings together the author's finest essays on women and gender written throughout the long span of her career. This volume includes three new essays published here for the very first time and a new general introduction. It also provides a concise introduction to each essay that describes how it came to be written and how it fits into her broader views about women and Byzantium.

The experience of employment of the mathematical cartography methods in cosmology

2017 ◽  
Vol 923 (5) ◽  
pp. 7-16
Author(s):  
A.V. Kavrayskiy
Keyword(s):  
Background Radiation ◽  
Three Dimensional ◽  
Spherical Coordinates ◽  
Linear Element ◽  
Microwave Background ◽  
Euclidian Space ◽  
Microwave Background Radiation ◽  
Rectangular Coordinates ◽  
The Universe ◽  
Length Distortion

The experience of mathematical modeling of the 3D-sphere in the 4D-space and projecting it by mathematical cartography methods in the 3D-Euclidian space is presented. The problem is solved by introduction of spherical coordinates for the 3D-sphere and their transformation into the rectangular coordinates, using the mathematical cartography methods. The mathematical relationship for calculating the length distortion mp(s) of the ds linear element when projecting the 3D-sphere from the 4-dimensional Euclidian space into three-dimensional Euclidian space is derived. Numerical examples, containing the modeling of the ds small linear element by spherical coordinates of 3D-sphere, projecting this sphere into the 3D-Euclidian space and length of ds calculating by means of its projection dL and size of distortion mp(s) are solved. Based on the model of the Universe known in cosmology as the 3D-sphere, the hypothesis of connection between distortion mp(s) and the known observed effects Redshift and Microwave Background Radiation is considered.

Laws of Nature

2018 ◽  
Keyword(s):  
Philosophy Of Science ◽  
Laws Of Nature ◽  
Current Debate ◽  
Scientific Theories ◽  
Law Of Nature ◽  
First Time ◽  
The Universe

The concept of a law of nature, while familiar, is deeply puzzling. Theorists such as Descartes think a divine being governs the universe according to the laws which follow from that being’s own nature. Newton detaches the concept from theology and is agnostic about the ontology underlying the laws of nature. Some later philosophers treat laws as summaries of events or tools for understanding and explanation, or identify the laws with principles and equations fundamental to scientific theories. In the first part of this volume, essays from leading historians of philosophy identify central questions: are laws independent of the things they govern, or do they emanate from the powers of bodies? Are the laws responsible for the patterns we see in nature, or should they be collapsed into those patterns? In the second part, contributors at the forefront of current debate evaluate the role of laws in contemporary Best System, perspectival, Kantian, and powers- or mechanisms-based approaches. These essays take up pressing questions about whether the laws of nature can be consistent with contingency, whether laws are based on the invariants of scientific theories, and how to deal with exceptions to laws. These twelve essays, published here for the first time, will be required reading for anyone interested in metaphysics, philosophy of science, and the histories of these disciplines.

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