A5087672044- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Geophysics and Gravity Measurements
- Relativity and Gravitational Theory
- Spectroscopy and Laser Applications
- Astro and Planetary Science
- Laser-induced spectroscopy and plasma
- Particle physics theoretical and experimental studies
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Laser Design and Applications
- Black Holes and Theoretical Physics
- Noncommutative and Quantum Gravity Theories
- History and Developments in Astronomy
- Handwritten Text Recognition Techniques
- Gamma-ray bursts and supernovae
University of Manchester
1976-2024
SKA Observatory
1976-2021
Instituto Argentino de Radioastronomía
1983
Voyage 2050 White Paper highlighting the unique science opportunities using spectral distortions of cosmic microwave background (CMB). CMB probe many processes throughout history Universe. Precision spectroscopy, possible with existing technology, would provide key tests for expected within cosmological standard model and open an enormous discovery space to new physics. This offers scientific furthering our understanding inflation, recombination, reionization structure formation as well dark...
We present updated constraints on the variation of fine structure constant, $\alpha_{\rm EM}$, and effective electron rest mass, $m_{\rm e}$, during cosmological recombination era. These two fundamental constants directly affect ionization history at redshift $z\simeq 1100$ thus modify temperature polarisation anisotropies cosmic microwave background (CMB) measured precisely with {\it Planck }. The EM}$ tighten slightly due to improved Planck} 2018 data but otherwise remain similar previous...
Observations of the CMB today allow us to answer detailed questions about properties our Universe, targeting both standard and non-standard physics. In this paper, we study effects varying fundamental constants (i.e., fine-structure constant, $α_{\rm EM}$, electron rest mass, $m_{\rm e}$) around last scattering using recombination codes CosmoRec Recfast++. We approach problem in a pedagogical manner, illustrating importance various on free fraction, Thomson visibility function power spectra,...
Abstract This paper discusses the science case for a sensitive spectro-polarimetric survey of microwave sky. Such would provide tomographic and dynamic census three-dimensional distribution hot gas, velocity flows, early metals, dust, mass in entire Hubble volume, exploit CMB temperature polarisation anisotropies down to fundamental limits, track energy injection absorption into radiation background across cosmic times by measuring spectral distortions blackbody emission. In addition its...
In some extensions of the standard model particle physics, values fundamental coupling constants vary in space and time. Some observations quasars hint at time spatial variation fine structure constant $\ensuremath{\alpha}$. Here, Bekenstein-Sandvik-Barrow-Magueijo (BSBM) (which posits existence a scalar field driving evolution electric charge $e$) is tested against quasar Planck satellite cosmic microwave background (CMB) data. this model, variations $e$ are coupled to matter density...
Following the pioneering observations with COBE in early 1990s, studies of cosmic microwave background (CMB) have focused on temperature and polarization anisotropies. CMB spectral distortions - tiny departures energy spectrum from that a perfect blackbody provide second, independent probe fundamental physics, reach deep into primordial Universe. The theoretical foundation has seen major advances recent years, which highlight immense potential this emerging field. Spectral property Universe...
Varying fundamental constants (VFC) [e.g., the fine-structure constant, $\alpha_{\rm EM}$] can arise in numerous extended cosmologies. Through their effect on decoupling of baryons and photons during last scattering reionisation, these models be directly constrained using measurements cosmic microwave background (CMB) temperature polarization anisotropies. Previous investigations focused mainly time-independent changes to values constants. Here we generalize time-dependent variations....
ABSTRACT The cosmological recombination radiation (CRR) is one of the guaranteed spectral distortion signals from early Universe. CRR photons hydrogen and helium pre-date last scattering process as such allow probing physical phenomena in pre-recombination era. Here, we compute modifications to caused by dark energy models varying electromagnetic fundamental constants. These new physics examples have seen increased recent activity connection with Hubble tension, motivating exploratory study...
Extensive observations of the H 166α (λ 21 cm) radio recombination line emission from galactic plane in longitude range |$5^{\circ }\leq l\leq70^{\circ }$| are presented. A longitude–velocity diagram for ionized hydrogen this region has been constructed and it is found that bulk occurs within |$l\lt35^{\circ }$|. The also indicate distributed regions apparently free discrete sources properties similar to those conventional II regions.
NGC 1023, l'une des quelques galaxies lenticulaires riches en gaz actuellement connues a ete observee avec le Radio Telescope de Westerbork. L'hydrogene, qui atteint 1,5×10 9 M ○. , presente une cinematique et distribution la densite remarquables suggerent origine intergalactique probable arrivee recente. La structure HI autour 1023 semble irreguliere grumeaux
This paper discusses the science case for a sensitive spectro-polarimetric survey of microwave sky. Such would provide tomographic and dynamic census three-dimensional distribution hot gas, velocity flows, early metals, dust, mass in entire Hubble volume, exploit CMB temperature polarisation anisotropies down to fundamental limits, track energy injection absorption into radiation background across cosmic times by measuring spectral distortions blackbody emission. In addition its exceptional...
The cosmological recombination radiation (CRR) is one of the inevitable $Λ$CDM spectral distortions cosmic microwave background (CMB). While it shows a rich structure across dm-mm wavelengths, also smallest signals to target. Here we carry out detailed forecast for expected sensitivity levels required not only detect but extract information from CRR in presence foregrounds. We use ${\tt CosmoSpec}$ compute including all important radiative transfer effects and modifications dynamics. confirm...
The precision of recent experiments such as ${\it Planck}$ have allowed us to constrain standard and non-standard physics (e.g., due dark matter annihilation or varying fundamental constants) during the recombination epoch. However, we can also probe this era cosmic history using model-independent variations free electron fraction, $X_{\rm e}$, which in turn affects temperature polarization anisotropies microwave background. In paper, improve on previous efforts construct these generalised...
Recombination lines at 242, 328 and 408 MHz are reported from the direction of Galactic Centre H II regions W35 W43. The can only be explained in terms stimulated emission which appears to originate an extended, low-density, low-emission measure region line-of-sight Centre. recombination not strongly enhanced by effects, consistent with electron temperature ≈ 4000 K. None low-frequency three sources studied show significant pressure broadening.
A region 0°.7 × 0°.8 around the SB0 galaxy NGC 1023 has been surveyed in H I with MK IA radio telescope (beamwidth 0°.2 0°.2). 1023, which a heliocentric velocity of 607 km s-1, shows clear rotation, hydrogen mass 1.1 109M⊙ and total mass-to- luminosity ratio 8.5. Of particular interest is discovery possible intergalactic cloud 14arcmin from 882 s-1 0.7 109M⊙. There no apparent optical counterpart to this object. The members group divide into two distinct groupings. lower at 732 corrected...
Observations of H166α recombination line emission from 13 positions within the IC 1795, 1805 and 1848 H II region complex are presented. A mean electron temperature |$6900_{-1400}^{+2700}\,\text{K}$| is obtained for extended low-brightness parts region. It suggested that similar regions could give rise to ‘ diffuse ’ galactic ridge.