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2026.07.21
Mapping the large scale structure of the Universe in radio wavelength with MeerKLASS and SKAO
Neutral hydrogen intensity mapping (HIIM) has become an emerging alternative probe of the cosmic large scale structure of the Universe. Radio telescopes can be used to map the distribution of the 21cm emission line of neutral hydrogen, yielding intrinsically spectroscopic surveys of LSS. In this talk, I will review the progress of the HIIM surveys of LSS, focusing in particular on the MeerKLASS...
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2026.07.03
New Theoretical Insights into Black Hole Coronae
What powers the hard, non-thermal X-rays from accreting black holes has been a longstanding mystery. In this talk, I will address the underlying question of what energizes the plasma of the Comptonizing “corona” against the strong inverse Compton cooling losses with first-principle particle-in-cell simulations of magnetic reconnection subject to radiative cooling losses in magnetized electron...
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2026.06.29
Linking Plasma Dynamics, Particle Acceleration, and Multi-Messenger Emission in Active Galactic Nuclei
Recent advances in multi-messenger and time-domain astronomy are opening a new window onto the high-energy universe and transforming our understanding of active galactic nuclei (AGNs). Observations across photons, neutrinos, and cosmic rays now make it possible to probe how supermassive black holes power some of the most extreme plasma environments in nature, including jets, coronae, and accret...
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2026.05.27
Charaterizing Cosmic Acceleration with Geometric Probes from Galaxy Surveys
The underlying physics of cosmic acceleration remains one of the most profound mysteries in cosmology after almost three decades since its discovery from Type Ia supernovae. Galaxy surveys, such as Sloan Digital Sky Survey (SDSS) and Dark Energy Spectroscopic Instrument (DESI), have provided us with independent evidence for cosmic acceleration. Moreover, recent DESI DR2 measurements of Baryon A...
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2026.05.22
Time Delay cosmography and the Hubble tension
Strongly lensed quasars can be used to measure the Hubble constant, provided the time delays between the lensed images can be measured. The method depends on a model for the lensing galaxy but is fully independent of any other method to measure H0. It is therefore crucial to confirm (or not) the Hubble tension. The method comes however with its own systematics that are currently addressed by th...
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2026.06.18
Physics-Informed Machine Learning for precise and accurate weak lensing shear estimation
Weak gravitational lensing has served as an important probe for large-scale structure and cosmology for decades. Stage-IV surveys require both sub-percent calibration accuracy and high statistical precision for WL shear estimation, yet traditional estimators struggle with realistic galaxy complexity while machine-learning methods often introduce biases. I will introduce a physics-informed machi...
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2026.05.12
A model independent Alcock–Paczynski test using the profiles of voids and clusters
Robust inference with minimal dependence on uncertain models of physical processes is increasingly essential for precision cosmology. We present a geometrical test based on a null statistic constructed from the distribution of galaxies around cosmological voids and clusters of galaxies. The key idea is to form crossed density contrasts whose leading linear redshift-space distortion terms cancel...
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2026.05.12
SPT-selected protoclusters and the early emergence of the hot intracluster gas
The South Pole Telescope (SPT) has discovered a large sample of millimetre point sources in the 2500 deg^2 SPT-SZ survey. Follow-up observations with ALMA show that about 90% of these sources are strongly lensed dusty star-forming galaxies (DSFGs), while the remaining ~10% are compact groups of DSFGs at z~3-7, representing protocluster cores caught during their most intense phase of star format...
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2026.04.23
Could we detect the hot CGM in X-ray?
Extended, diffuse soft X-ray emission has been widely detected around individual galaxies and is commonly attributed to either galactic feedback processes or gravitational heating, with the latter expected to be efficient primarily in massive systems. However, in most galaxies the observed X-ray radiation efficiency—defined as the fraction of feedback energy emitted in X-rays—is far below uni...
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2026.04.24
A 3D view of the Milky Way spiral arms with Gaia DR3
Due to Gaia’s outstanding astrometric capabilities, the field of Galactic cartography is currently undergoing a revolution, reaching a level of detail and precision that has not been seen before. In this talk I will present some of the recent results in this field: imprints of major mergers in the Galaxy, chemical inhomogeneities in the Galactic disk, and disequilibrium features in stellar dis...
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