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Full-Text Articles in Astrophysics and Astronomy
Significance Of Gravitational Nonlinearities On The Dynamics Of Disk Galaxies, Alexandre Deur, Corey Sargent, Balša Terzić
Significance Of Gravitational Nonlinearities On The Dynamics Of Disk Galaxies, Alexandre Deur, Corey Sargent, Balša Terzić
Physics Faculty Publications
The discrepancy between the visible mass in galaxies or galaxy clusters and that inferred from their dynamics is well known. The prevailing solution to this problem is dark matter. Here we show that a different approach, one that conforms to both the current standard model of particle physics and general relativity (GR), explains the recently observed tight correlation between the galactic baryonic mass and the measured accelerations in the galaxy. Using direct calculations based on GR's Lagrangian and parameter-free galactic models, we show that the nonlinear effects of GR make baryonic matter alone sufficient to explain this observation. Our approach …
Waveband Luminosity Correlations In Flux-Limited Multiwavelength Data, Jack Singal, V. Petrosian, Sami Malik, Jibran Haider
Waveband Luminosity Correlations In Flux-Limited Multiwavelength Data, Jack Singal, V. Petrosian, Sami Malik, Jibran Haider
Physics Faculty Publications
We explore the general question of correlations among different waveband luminosities in a flux-limited multiband observational data set. Such correlations, often observed for astronomical sources, may be either intrinsic or induced by the redshift evolution of the luminosities and the data truncation due to the flux limits. We first address this question analytically. We then use simulated flux-limited data with three different known intrinsic luminosity correlations and prescribed luminosity functions and evolution similar to the ones expected for quasars. We explore how the intrinsic nature of luminosity correlations can be deduced, including exploring the efficacy of partial correlation analysis with …
A Determination Of The Gamma-Ray Flux And Photon Spectral Index Distributions Of Blazars From The Fermi-Lat 3lac, Jack Singal
A Determination Of The Gamma-Ray Flux And Photon Spectral Index Distributions Of Blazars From The Fermi-Lat 3lac, Jack Singal
Physics Faculty Publications
We present a determination of the distributions of gamma-ray photon flux – the so-called LogN–LogS relation – and photon spectral index for blazars, based on the third extragalactic source catalogue of the Fermi Gamma-ray Space Telescope's Large Area Telescope, and considering the photon energy range from 100 MeV to 100 GeV. The data set consists of the 774 blazars in the so-called Clean sample detected with a greater than approximately 7σ detection threshold and located above ±20° Galactic latitude. We use non-parametric methods verified in previous works to reconstruct the intrinsic distributions from the observed ones …