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91̽»¨
Black Hole

Lensing of space time around a black hole. At 91̽»¨ we study black holes observationally and theoretically on all size and time scales - it is some of our core work.

Credit: ALAIN RIAZUELO, IAP/UPMC/CNRS. CLICK HERE TO VIEW MORE IMAGES.

Prof. David Alonso

Associate Professor of Cosmology

Sub department

  • Astrophysics

Research groups

  • Beecroft Institute for Particle Astrophysics and Cosmology
  • Rubin-LSST
David.Alonso@physics.ox.ac.uk
Telephone: 01865 (2)288582
Denys Wilkinson Building, room 532B
  • About
  • Publications

Insights on gas thermodynamics from the combination of x-ray and thermal Sunyaev-Zel’dovich data cross correlated with cosmic shear

Physical Review D American Physical Society (APS) 112:4 (2025) 043525

Authors:

Adrien La Posta, David Alonso, Nora Elisa Chisari, Tassia Ferreira, Carlos García-García

Abstract:

We measure the cross-correlation between cosmic shear from the third-year release of the Dark Energy Survey, thermal Sunyaev-Zel’dovich (tSZ) maps from , and x-ray maps from ROSAT. We investigate the possibility of developing a physical model able to jointly describe both measurements, simultaneously constraining the spatial distribution and thermodynamic properties of hot gas. We find that a relatively simple model is able to describe both sets of measurements and to make reasonably accurate predictions for other observables (the tSZ autocorrelation, its cross-correlation with x-rays, and tomographic measurements of the bias-weighted mean gas pressure). We show, however, that contamination from x-ray active galactic nuclei (AGN), as well as the impact of nonthermal pressure 91̽»¨, must be incorporated in order to fully resolve tensions in parameter space between different data combinations. Combining the tSZ and x-ray cross-correlations with cosmic shear we obtain simultaneous constraints on the mass scale at which half of the gas content has been expelled from the halo, log 10 M c = 14.8 3 − 0.23 + 0.16 , on the polytropic index of the gas, Γ = 1.14 4 − 0.013 + 0.016 , and on the ratio of the central gas temperature to the virial temperature α T = 1.3 0 − 0.28 + 0.15 , marginalizing over AGN contributions to the signal.

The impact of galaxy bias on cross-correlation tomography

(2025)

Authors:

Sara Maleubre, Matteo Zennaro, David Alonso, Ian McCarthy, Matthieu Schaller, Joop Schaye

The Simons Observatory: science goals and forecasts for the enhanced Large Aperture Telescope

Journal of Cosmology and Astroparticle Physics IOP Publishing 2025:08 (2025) 034

Authors:

M Abitbol, I Abril-Cabezas, S Adachi, P Ade, AE Adler, P Agrawal, J Aguirre, Z Ahmed, S Aiola, T Alford, A Ali, David Alonso, MA Alvarez, R An, K Arnold, P Ashton, Z Atkins, J Austermann, Susanna Azzoni, C Baccigalupi, A Baleato Lizancos, D Barron, P Barry, J Bartlett, Michael Jones, Adrien La Posta, Jamie Leech, Angela C Taylor

Abstract:

We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of the Planck satellite. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at redshifts z ≲ 3; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from the Vera C. Rubin Observatory of overlapping sky.

The Simons Observatory: Assessing the Impact of Dust Complexity on the Recovery of Primordial $B$-modes

(2025)

Authors:

Yiqi Liu, Susanna Azzoni, Susan E Clark, Brandon S Hensley, Là O Vacher, David Alonso, Carlo Baccigalupi, Michael L Brown, Alessandro Carones, Jens Chluba, Jo Dunkley, Carlos Hervías-Caimapo, Bradley R Johnson, Nicoletta Krachmalnicoff, Giuseppe Puglisi, Mathieu Remazeilles, Kevin Wolz

First Constraints from Marked Angular Power Spectra with Subaru Hyper Suprime-Cam Survey First-Year Data

(2025)

Authors:

Jessica A Cowell, Joaquin Armijo, Leander Thiele, Gabriela A Marques, Camila P Novaes, Daniela Grandón, Sihao Cheng, Masato Shirasaki, David Alonso, Jia Liu

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