A5005401243- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Scientific Research and Discoveries
- Black Holes and Theoretical Physics
- Superconducting and THz Device Technology
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- GNSS positioning and interference
- Mechatronics Education and Applications
- Experimental and Theoretical Physics Studies
- Advanced Mathematical Theories and Applications
- Adaptive optics and wavefront sensing
- Chaos control and synchronization
- Computational Physics and Python Applications
- Advanced Control Systems Design
- Advanced Fiber Optic Sensors
- Soil Moisture and Remote Sensing
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Experimental Learning in Engineering
University of the Western Cape
2015-2025
Universidade do Porto
2022-2025
Institute of Astrophysics and Space Sciences
2022-2025
Queen Mary University of London
2021-2024
University of Padua
2019-2021
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2019-2021
Istituto Nazionale di Fisica Nucleare
2019
Universidade Federal de Pernambuco
2018
SKA Telescope, South Africa
2018
Jet Propulsion Laboratory
2018
Abstract We present a detailed overview of the cosmological surveys that we aim to carry out with Phase 1 Square Kilometre Array (SKA1) and science they will enable. highlight three main surveys: medium-deep continuum weak lensing low-redshift spectroscopic HI galaxy survey over 5 000 deg 2 ; wide deep intensity mapping (IM) 20 from $z = 0.35$ 3; deep, high-redshift IM 100 3$ 6. Taken together, these achieve an array important scientific goals: measuring equation state dark energy \sim...
Following the first two annual intensity mapping workshops at Stanford in March 2016 and Johns Hopkins June 2017, we report on recent advances theory, instrumentation observation that were presented these meetings some of opportunities challenges identified looking forward. With preliminary detections CO, [CII], Lya low-redshift 21cm, a host experiments set to go online next few years, field is rapidly progressing all fronts, with great anticipation for flood new exciting results. This...
Abstract We present results from MeerKAT single-dish H i intensity maps, the final observations to be performed in L-band Large Area Synoptic Survey (MeerKLASS) campaign. The represent deepest maps date, produced 41 repeated scans over $236\, \deg ^2$, providing 62 hours of observational data for each 64 dishes before flagging. By introducing an iterative self-calibration process, estimated thermal noise reconstructed is limited ∼ 1.21 mK (1.2 × theoretical level). This will sub-dominant...
Next-generation cosmological surveys will probe ever larger volumes of the universe, including largest scales, near and beyond horizon. On these galaxy power spectrum carries signatures local primordial non-Gaussianity (PNG) horizon-scale general relativistic (GR) effects. However, cosmic variance limits detection Combining different via multi-tracer method allows us to reduce effect variance. This benefits from large bias differences between two tracers underlying dark matter distribution,...
Abstract The Square Kilometre Array (SKA) is a planned large radio interferometer designed to operate over wide range of frequencies, and with an order magnitude greater sensitivity survey speed than any current telescope. SKA will address many important topics in astronomy, ranging from planet formation distant galaxies. However, this work, we consider the perspective as facility for studying physics. We review four areas which expected make major contributions our understanding fundamental...
We present a detection of correlated clustering between MeerKAT radio intensity maps and galaxies from the WiggleZ Dark Energy Survey. find $7.7\sigma$ cross-correlation power spectrum, amplitude which is proportional to product HI density fraction ($\Omega_{\rm HI}$), bias ($b_{\rm HI}$) coefficient ($r$). therefore obtain constraint $\Omega_{\rm HI} b_{\rm r\,{=}\,[0.86\,{\pm}\,0.10\,({\rm stat})\,{\pm}\,0.12\,({\rm sys})]\,{\times}\,10^{-3}$, at an effective scale $k_{\rm...
While most purpose-built 21cm intensity mapping experiments are close-packed interferometer arrays, general-purpose dish arrays should also be capable of measuring the cosmological signal. This can achieved efficiently if array is used as a collection scanning autocorrelation dishes rather than an interferometer. As first step towards demonstrating feasibility this observing strategy, we show that able to successfully calibrate dual-polarisation data from 64 MeerKAT in L-band (856-1712 MHz,...
Abstract The power spectrum and bispectrum of dark matter tracers are key complementary probes the Universe. Next-generation surveys will deliver good measurements bispectrum, opening door to improved cosmological constraints breaking parameter degeneracies, from combination bispectrum. Multi-tracer spectra have been used suppress cosmic variance mitigate effects nuisance parameters systematics. We present a multi-tracer formalism that can be applied next-generation survey data. Then we...
We discuss the ground-breaking science that will be possible with a wide area survey, using MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area Synoptic Survey). The current specifications of make it great fit for applications require large survey speeds but not necessarily high angular resolutions. In particular, cosmology, over $\sim 4,000 \, {\rm deg}^2$ 4,000$ hours potentially provide first ever measurements baryon acoustic oscillations 21cm intensity mapping technique, enough...
We present a systematic study of the intensity mapping technique using updated models for different emission lines from galaxies and identify which ones are more promising cosmological studies post reionization epoch. consider ${\rm Ly\alpha}$, H\alpha}$, H$\beta$, optical infrared oxygen lines, nitrogen CII CO rotational lines. then that OII, lowest best candidates to be used as IM probes. These form complementary set probes spectra. use reasonable experimental setups current, planned or...
Neutral Hydrogen Intensity Mapping (HI IM) surveys will be a powerful new probe of cosmology. However, strong astrophysical foregrounds contaminate the signal and their coupling with instrumental systematics further increases data cleaning complexity. In this work, we simulate realistic single-dish HI IM survey $5000$~deg$^2$ patch in $950 - 1400$ MHz range, both MID telescope SKA Observatory (SKAO) MeerKAT, its precursor. We include state-of-the-art simulations explore different foreground...
Measurements of galaxy clustering in upcoming surveys such as those planned for the Euclid and Roman satellites, SKA Observatory, will be sensitive to distortions from lensing magnification Doppler effects, beyond standard redshift-space distortions. The amplitude these contributions depends sensitively on bias evolution number density. Magnification quantifies change observed galaxies gained or lost by magnification, while physical density relative conserved case. These biases are given...
We use full sky simulations, including the effects of foreground contamination and removal, to explore multi-tracer synergies between a SKA-like 21cm intensity mapping survey LSST-like photometric galaxy redshift survey. In particular we study ratios auto cross-correlations two tracers as estimators ratio their biases, quantity that should benefit considerably from cosmic variance cancellation approach. show how well be able measure bias on very large scales (down $\ell \sim 3$), which is...
Abstract Next generation surveys will provide us with an unprecedented number of detections supernovae Type Ia and gravitational wave merger events. Cross-correlations such objects offer novel powerful insights into the large-scale distribution matter in universe. Both these sources carry information on their luminosity distance, but remain uninformative about redshifts; hence clustering analyses cross-correlations need to be carried out distance space, as opposed redshift space. In this...
Abstract Third-generation gravitational wave (GW) observatories such as the Einstein Telescope and Cosmic Explorer, together with LSST survey at Vera Rubin Observatory, will yield an abundance of extra-galactic transient objects. This opens exciting possibility using GW sources Supernovae Type Ia (SNIa) luminosity distance tracers large-scale structure for first time. The large volumes accessible to these surveys imply that we may need include relativistic corrections, lensing Doppler...
Abstract Gravitational waves (GWs) have rapidly become important cosmological probes since their first detection in 2015. As the number of detected events continues to rise, upcoming instruments like Einstein Telescope (ET) and Cosmic Explorer (CE) will observe millions compact binary (CB) mergers. These detections, coupled with galaxy surveys by such as DESI, Euclid, Vera Rubin Observatory, provide unique information on large-scale structure universe cross-correlating GWs distribution...
We characterise the primordial perturbations produced due to both inflaton and curvaton fluctuations in models where has a quadratic, cosine or hyperbolic potential, potential is characterised by usual slow-roll parameters. Isocurvature field can produce significant non-Gaussianity density field, contrast with adiabatic which negligible for canonical scalar fields. A non-self-interacting quadratic produces local-type that well described non-linearity parameter fNL, may be scale-dependent...
It is usually assumed that we will need to wait until next-generation surveys like Euclid, LSST and SKA, in order improve on the current best constraints primordial non-Gaussianity from Planck experiment. We show two contemporary surveys, with SKA precursor MeerKAT Dark Energy Survey (DES), can be combined using multi-tracer technique deliver an accuracy measurement of $f_{\rm NL}$ up three times better than Planck.
We study synergies between Hi 21 cm and H α intensity map observations, focusing on SKA1-like SPHEREx-like surveys. forecast how well such a combination can measure features in the angular power spectrum largest scales, that arise from primordial non-Gaussianity general relativistic effects. For first time we consider Doppler, Sachs–Wolfe, integrated SW effects separately. confirm single-tracer surveys their own cannot detect constrain parameter fNL only slightly better than Planck. Using...
The large-scale structure growth index γ provides a consistency test of the standard cosmology and is potential indicator modified gravity. We investigate constraints on from next-generation spectroscopic surveys, using power spectrum that observed in redshift space, i.e., angular spectrum. avoids need for an Alcock-Packzynski correction. It also naturally incorporates cosmic evolution wide-angle effects, without any approximation. include cross-correlations between bins, hybrid...
The growth rate of large-scale structure provides a powerful consistency test the standard cosmological model and probe possible deviations from general relativity. We use Fisher analysis to forecast constraints on combination next-generation spectroscopic surveys. In overlap survey volumes, we multi-tracer significantly reduce effect cosmic variance. non-overlap individual volumes are included in order utilise entire volume. observed angular power spectrum, which naturally includes all...
Next-generation cosmological surveys will observe larger cosmic volumes than ever before, enabling us to access information on the primordial Universe, as well relativistic effects. We consider forthcoming 21cm intensity mapping (SKAO) and optical galaxy (DESI Euclid), combining via multi-tracer cross-correlations that suppress variance ultra-large scales. In order fully incorporate wide-angle effects redshift-bin cross-correlations, together with lensing magnification other effects, we use...
The angular power spectrum is a gauge-independent observable that in principle the natural tool for analysing galaxy number counts. In practice, problem computational requirements next-generation spectroscopic surveys such as Euclid and Square Kilometre Array are currently unfeasible. We propose new method to save time spectra. This hybrid modelled on Fourier approach of treating relatively thick redshift bins (redshift width ~0.1) separate surveys. method, each bin further subdivided into...