A5083293733- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- History and Developments in Astronomy
- Astrophysical Phenomena and Observations
University of Hong Kong
2022-2024
Abstract Dark matter subhalos with extended profiles and density cores, globular star clusters of mass 10 6 –10 8 M ⊙ that live near the critical curves in galaxy cluster lenses can potentially be detected through their lensing magnification stars background galaxies. In this work, we study effect such have on lensed images, compare to case more well-studied microlensing by black holes curves. We find gradient distribution are important determining image properties. Both lead an asymmetry...
Recent observations of caustic-crossing galaxies at redshift 0.7 ≲ z 1 show a wealth transient events. Most them are believed to be microlensing events highly magnified stars. Earlier work predicts such should common near the critical curves (CCs) galaxy clusters (“near region”), but some found relatively far away from these CCs (“far region”). We consider possibility that substructure on milliarcsecond scales (few parsecs in lens plane) is boosting signal region. study combined...
We report the discovery of a transient seen in strongly lensed arc at redshift $z_{\rm s}=1.2567$ \emph{Hubble Space Telescope} imaging Abell 370 galaxy cluster. The is detected $29.51\pm0.14$ AB mag WFC3/UVIS F200LP difference image made using observations from two different epochs, obtained framework \emph{Flashlights} program, and also visible F350LP band ($m_{\rm F350LP} \approx 30.53\pm0.76$ mag). observed on negative-parity side critical curve distance $\sim 0.6"$ it, greater than...
Abstract Fuzzy dark matter (FDM), a scalar particle coupled to the gravitational field without self-interaction, whose mass range is m ∼ 10 −24 –10 −20 eV, one of promising alternative candidates cold matter. The quantum interference pattern, which unique structure FDM, can be seen in halos cosmological FDM simulations. In this paper, we first provide an analytic model subgalactic power spectrum originating from clumps halos, density distribution expressed by superposition size corresponds...
In this work, we present a constraint on the abundance of supergiant (SG) stars at redshift z ≈ 1, based recent observations strongly lensed arc redshift. First derived free-form model MACS J0416.1-2403 using data from Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) program. The new lens is 72 multiply galaxies that produce 214 multiple images, making it largest sample spectroscopically confirmed cluster. larger coverage in BUFFALO allowed us to measure shear up outskirts...
We present the highest-resolution images to date of caustics formed by wave dark matter (psi DM) fluctuations near critical curves cluster gravitational lenses. describe basic magnification features psi DM in source plane at high macromodel and discuss specific differences between standard cold (CDM) models. The unique generation demagnified counterimages (with respect from smooth macromodel) outside Einstein radius for is highlighted. Substructure CDM cannot generate with positive parity...
Abstract Many microlensed stars discovered by JWST closely follow the winding critical curve of A370 along “Dragon Arc” with m AB > 26.5, which we show comprises asymptotic giant branch observed level diffuse cluster stars, corresponding to ≃1% dark matter density. Most events appear inner edge curve, following an asymmetric band width ≃4.5 kpc that is skewed −0.7 ± 0.2 kpc. This asymmetry, argue, follows from parity difference in caustic structure inherent microlensing extends higher...
Once only accessible in nearby galaxies, we can now study individual stars across much of the observable universe aided by galaxy-cluster gravitational lenses. When a star, compact object, or multiple such objects foreground lens become aligned, they magnify background and timescale magnification peak limit its size to tens AU. The number frequency microlensing events therefore opens window into population objects, as well high-redshift stars. To assemble first statistical sample order...
We present a constraint on the abundance of supergiant (SG) stars at redshift z approx. 1, based recent observations strongly lensed arc this redshift. First we derive free-form model MACS J0416.1-2403 using data from BUFFALO program. The new lens is 72 multiply galaxies that produce 214 multiple images, making it largest sample spectroscopically confirmed cluster. larger coverage in allows us to measure shear up outskirts cluster, and extend range lensing constraints ~ 1 Mpc central region,...
Dark matter subhalos with extended profiles and density cores, globular stars clusters of mass $10^6-10^8 M_\odot$, that live near the critical curves in galaxy cluster lenses can potentially be detected through their lensing magnification background galaxies. In this work we study effect such have on lensed images, compare to case more well studied microlensing by black holes curves. We find gradient distribution are important determining image properties. Both lead an asymmetry between...
Observations of caustic-crossing galaxies at redshift $0.7<z<1$ show a wealth transient events. Most them are believed to be microlensing events highly magnified stars. Earlier work predicted such should common near the critical curves (CCs) galaxy clusters, but some found relatively far away from these CCs. We consider possibility that substructure on milliarcsecond scales (few parsecs in lens plane) is boosting signal. study combined magnification macrolens, millilenses, and microlenses...
We study the nature of transient events detected in "Dragon Arc", a star-forming galaxy at redshift $0.7251$ that is gravitationally lensed by cluster Abell 370. In particular, we focus on subset ten transients are identified as unresolved young star clusters deep broadband, F200LP, taken part "Flashlights" Hubble Space Telescope program, showing flux variations $\sim 10-20\%$ over period about year. Here develop several methods to address whether stellar microlensing alone capable...
Microlensed stars recently discovered by JWST & HST follow closely the winding critical curve of A370 along all sections ``Dragon Arc" traversed curve. These transients are fainter than $m_{AB}>26.5$, corresponding to Asymptotic Giant Branch (AGB) and microlensed diffuse cluster observed with $\simeq 18M_\odot/pc^2$, or about 1$\% projected dark matter density. Most appear inner edge curve, following an asymmetric band width 4$kpc that is skewed $-0.7\pm0.2$kpc. Some skewness expected as...
We present the highest resolution images to date of caustics formed by wave dark matter ($\psi$DM) fluctuations near critical curves cluster gravitational lenses. describe basic magnification features $\psi$DM in source plane at high macromodel and discuss specific differences between standard cold (CDM) models. The unique generation demagnified counterimages outside Einstein radius for is highlighted. Substructure CDM cannot generate such positive parity, thus providing a definitive way...
We report the discovery of a transient seen in strongly lensed arc at redshift $z_{\rm s}=1.2567$ \emph{Hubble Space Telescope} imaging Abell 370 galaxy cluster. The is detected $29.51\pm0.14$ AB mag WFC3/UVIS F200LP difference image made using observations from two different epochs, obtained framework \emph{Flashlights} program, and also visible F350LP band ($m_{\rm F350LP} \approx 30.53\pm0.76$ mag). observed on negative-parity side critical curve distance $\sim 0.6"$ it, greater than...