Physics and Astronomy: Recent submissions
Now showing items 281-300 of 520
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Broad-band radio polarimetry of disc galaxies and AGN with KAT-7
(Oxford University Press, 2020-10-24)We report broad-band (1.2–1.9 GHz) radio continuum observations at arcminute resolutions of two nearby disc galaxies, NGC 1808 and NGC 1097, and four active galactic nuclei (AGN)-powered radio sources: PKS B1934−638, PKS ... -
Effect of the environment on star formation activity and stellar mass for star-forming galaxies in the COSMOS field
(2020-11)We investigate the relationship between the environment and the galaxy main sequence (the relationship between stellar mass and star formation rate), as well as the relationship between the environment and radio luminosity ... -
The evolution of the low-frequency radio AGN population to z 1.5 in the ELAIS N1 field
(Advance Access publication, 2020-11-13)We study the cosmic evolution of radio sources out to z 1.5 using a GMRT 610 MHz survey covering ∼1.86 deg2 of the ELAIS N1 field with a minimum/median rms noise 7.1/19.5 μJy beam−1 and an angular resolution of 6 arcsec. ... -
Extremely deep 150 MHz source counts from the LoTSS deep fields
(EDP Sciences, 2021)With the advent of new generation low-frequency telescopes, such as the LOw Frequency ARray (LOFAR), and improved calibration techniques, we have now started to unveil the subgigahertz radio sky with unprecedented depth ... -
A comparison of the microstructures, thermal and mechanical properties of pressed and sintered TieCu, TieNi and TieCueNi alloys intended for dental applications
(Journal of Alloys and Compounds, 2020)The effect of Ni and Cu on the a/b phase transformation temperature, possible retention of the b-phase, and mechanical properties of Ti, Tie13Cu, Tie4.5Ni and Tie13Cue4.5Ni (compositions in wt. %) alloys were investigated. ... -
A new auroral phenomenon, the anti-black aurora
(Nature, 2021)Black auroras are small-scale features embedded in the diffuse background aurora, typically occurring post-substorm after magnetic midnight and with an eastward drift imposed. Black auroras show a significant reduction in ... -
The evolving role of science in society
(José Frantz, 2020)The world is experiencing a traumatic change brought about by the Covid-19 pandemic. It is traumatic because it is sudden and affects everyone around the globe at once. Nothing like this has ever happened so rapidly before, ... -
Probing beyond-Horndeski gravity on ultra-large scales
(IOP Publishing Ltd, 2020)The beyond-Horndeski gravity has recently been reformulated in the dark energy paradigm — which has been dubbed, Unified Dark Energy (UDE). The evolution equations for the given UDE appear to correspond to a non-conservative ... -
Multi-scale perturbation theory. Part I. Methodology and leading-order bispectrum corrections in the matter-dominated era
(IOP Publishing Ltd, 2020)Two-parameter perturbation theory is a scheme tailor-made to consistently include nonlinear density contrasts on small scales (< 100 Mpc), whilst retaining a traditional approach to cosmological perturbations in the ... -
Detecting the relativistic galaxy bispectrum
(IOP Publishing Ltd, 2020)The Fourier galaxy bispectrum is complex, with the imaginary part arising from leading-order relativistic corrections, due to Doppler, gravitational redshift and related lineof-sight effects in redshift space. The detection ... -
Galaxy and Mass Assembly (GAMA): Demonstrating the power of WISE in the study of Galaxy Groups to z < 0.1
(IOP Publishing, 2020)Combining high-fidelity group characterisation from the Galaxy and Mass Assembly (GAMA) survey and source-tailored z < 0.1 photometry from the WISE survey, we present a comprehensive study of the properties of ungrouped ... -
The VLA-COSMOS 3 GHz Large Project: Evolution of specific star formation rates out to z∼5
(IOP Publishing, 2020)We provide a coherent, uniform measurement of the evolution of the logarithmic star formation rate (SFR) – stellar mass (M∗) relation, called the main sequence of star-forming galaxies (MS), for starforming and all galaxies ... -
How well can we measure the stellar mass of a galaxy: The impact of the assumed star formation history model in SED fitting
(IOP Publishing, 2020)The primary method for inferring the stellar mass (M∗) of a galaxy is through spectral energy distribution (SED) modeling. However, the technique rests on assumptions such as the galaxy star formation history and dust ... -
A flexible method for estimating luminosity functions via Kernel Density Estimation
(IOP Publishing, 2020)We propose a flexible method for estimating luminosity functions (LFs) based on kernel density estimation (KDE), the most popular nonparametric density estimation approach developed in modern statistics, to overcome ... -
Cosmological 3D Hi Gas Map with HETDEX Lyα Emitters and eBOSS QSOs at z = 2: IGM-Galaxy/QSO Connection and a ∼ 40-Mpc Scale Giant Hii Bubble Candidate
(IOP Publishing, 2020)We present cosmological (30−400 Mpc) distributions of neutral hydrogen (H i) in the intergalactic medium (IGM) traced by Lyα emitters (LAEs) and QSOs at z = 2.1–2.5, selected with the data of the ongoing Hobby–Eberly ... -
Planck 2018 results. XI. Polarized dust foregrounds
(EDP Sciences, 2020)The study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (CMB) polarization in the quest for the curl-like B-mode polarization from primordial gravitational waves and ... -
Improvements in cosmological constraints from breaking growth degeneracy
(EDP Sciences, 2020)The key probes of the growth of a large-scale structure are its rate f and amplitude σ8. Redshift space distortions in the galaxy power spectrum allow us to measure only the combination fσ8, which can be used to constrain ... -
Non-linear damping of superimposed primordial oscillations on the matter power spectrum in galaxy surveys
(IOP Publishing Ltd, 2020)Galaxy surveys are an important probe for superimposed oscillations on the primordial power spectrum of curvature perturbations, which are predicted in several theoretical models of inflation and its alternatives. In order ... -
Multipoles of the relativistic galaxy bispectrum
(IOP Publishing Ltd, 2020)Above the equality scale the galaxy bispectrum will be a key probe for measuring primordial non-Gaussianity which can help differentiate between different inflationary models and other theories of the early universe. On ... -
The Hubble constant tension with next-generation galaxy surveys
(IOP Publishing Ltd, 2020)The rate at which the universe is expanding today is a fundamental parameter in cosmology which governs our understanding of structure formation and dark energy. However, current measurements of the Hubble constant, H0, ...