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2024.04.15

X-ray emissions from the large scale structure of the Universe with an eROSITA focus

<p>I will present the maps of the large scale structure at soft X-ray wavelength obtained by eROSITA. I will discuss how the observed emission unravels the properties of the circum-galactic medium of our Milky-Way and nearby galaxies.Then I discuss what astrophysical and cosmological information is contained in the map subtended by X-ray detected clusters and Active galactic nuclei</p>

2024.03.29

Dust Dynamics in Planet Formation Processes & Towards Multi-stage Studies

<p>Dust plays an important&nbsp;role in planet formation as they grow from micron sized grains to over Mm sized planets. The intermediate stage, to form km-sized planetesimals from mm-cm sized dust particles, has been found to be difficult. These mm-cm sized dust particles frequently distribute in ring-like structures in protoplanetary disks as revealed in ALMA observations. Here, I present a series of...</p>

2024.03.20

AGN selection and demographics: a new age with JWST/MIRI

<p>Completing the census of active galactic nuclei (AGN) activity is the key to study the build-up of supermassive black holes (SMBHs) and understand their relations with the host galaxy properties. Nevertheless, many AGNs are obscured by dust and gas, making the identification of such systems a challenging task even today. In this talk, I will present the first results on the AGN identifications ...</p>

2024.02.28

Weak Lensing Without Shape Noise

<p>Weak gravitational lensing imprints a coherent distortion onto the observed shapes of distant galaxies. At the image level, this gravitational shear degenerates with the intrinsic shape of galaxies, and the weak lensing signal-to-noise from an individual galaxy is of order 0.01. I will describe Kinematic Lensing, a new technique combining imaging and galaxy kinematics to measure weak lensing wi...</p>

2023.12.25

Constraining the Cosmic Partition of IGM and CGM Baryons with FRB Foreground Mapping

<p>The frequency shifts measured in extragalactic Fast radio bursts (FRB)s probe the total column of ionized gas in the foreground, including large contributions from the CGM and IGM. By combining this information with both deep and wide &nbsp;spectroscopic observations of foreground galaxies, the information content is enhanced. The wide-field data &nbsp;(∼10s of Mpc scales) allows us to reconstruct the u...</p>

2023.12.25

A cooling anomaly of white dwarfs

<p>Data from the Gaia satellite are revolutionizing many fields of astronomy. I will present two related discoveries about white dwarfs: one is an extreme cooling anomaly upon phase transition of some white dwarfs, which stops their cooling for almost 10 Gyrs, and the other is the existence of merger products among single white dwarfs. I will show interesting solution to explain the anomaly and th...</p>

2023.12.18

Probing Parity with Galaxy Distributions and Beyond

<p>Galaxies&#39; four-point correlation functions provide insights into parity symmetry at cosmological scales. In this talk, I will present our data analysis on the BOSS galaxy sample with a focus on various observational effects. I will also discuss some future aspects of extending the analysis, including models and connection with other observables. In addition, I will also discuss an alternative i...</p>

2023.12.18

Electromagnetic fireworks from erupting magnetars

<p>Highly magnetized neutron stars are a source of extreme transients observed in different bands, like the fast radio burst (FRB) and associated hard X-ray burst from the Galactic magnetar SGR 1935+2154. The origin of such outbursts, hard X-rays on the one hand and millisecond duration FRBs on the other hand, is still unknown. We present a global model for various kinds of such magnetar outbursti...</p>

2023.11.27

Multi-Messenger Probes on Dark Matter Beyond WIMPs

<p>We will discuss two promising dark matter scenarios: axion-like particle dark matter and primordial black hole dark matter. We begin with radio telescope probes on axion-like dark matter. We will discuss the axion-photon conversion around neutron stars which results in the radio emission and the 21 cm probes through the effects on large scale structure formation suppression. We then turn our at...</p>

2023.11.24

Tidal Disruption Events: Probes of Accretion Physics and Black Hole Demographics

<p>Tidal disruption events (TDEs) provide unique laboratories to&nbsp;study the demographics, immediate stellar and gaseous environments, and&nbsp;accretion physics of the massive black hole population. Over the past&nbsp;few years, time domain sky surveys such as the optical Zwicky Transient&nbsp;Facility (ZTF) have led to a surge of TDE discoveries in galaxy centers.&nbsp;This talk highlights our efforts to constrain th...</p>