XRISM/Resolve observations of Hercules X-1: a pulsating, highly broadened Fe K emission line from the neutron star accretion column

Posted by klaurent MIT

Kavli Affiliate: Erin Kara | Summary:The study of X-ray pulsar accretion columns helps us characterize accretion physics in this extreme regime of strong gravity and strong magnetic fields. Previous observations of the X-ray pulsar Hercules X-1 revealed a highly broadened Fe K emission line, associated with Doppler motions exceeding 0.1c, suggesting its origin in the […]


Continue.. XRISM/Resolve observations of Hercules X-1: a pulsating, highly broadened Fe K emission line from the neutron star accretion column

Tracking thermal transport in colloidal quantum dot films using in-situ time-resolved X-ray diffraction

Posted by klaurent Berkeley

Kavli Affiliate: Paul Alivisatos | Summary:Colloidal quantum dots (QDs) and their thin-films are increasingly used in electronic and photonic devices replacing traditional bulk semiconductors. However, thermal properties of the QDs are comparatively underexplored relative to device development efforts. This study shows the use of time-resolved X-ray diffraction as a contact-free method to probe the thermal […]


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Formation and Redshift Evolution of Dark Matter Spikes

Posted by klaurent MIT

Kavli Affiliate: Lina Necib | Summary:Dark matter density spikes forming around adiabatically growing black holes can dramatically enhance indirect and direct detection signals. Canonical predictions, however, assume a zero-mass seed in a purely dark matter environment and do not track the long-term dynamical impact of surrounding stars. We present a semi-analytic framework that first generalizes […]


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Chemistry and Isotope Ratios of Substellar Atmospheres in the $β$ Pictoris Young Moving Group and Vicinity

Posted by klaurent Caltech

Kavli Affiliate: Dimitri Mawet| Summary:Measuring the chemical and isotopic compositions of gas giants and brown dwarfs provides insights into their formation pathways and birth environments. 2MASS J0249-0557 c is an L2-type planetary mass companion ($sim 12 M_mathrmJup$) orbiting a pair of brown dwarfs in the $β$ Pic young moving group and vicinity. Its mass places […]


Continue.. Chemistry and Isotope Ratios of Substellar Atmospheres in the $β$ Pictoris Young Moving Group and Vicinity

Chemistry and Isotope Ratios of Substellar Atmospheres in the $β$ Pictoris Young Moving Group

Posted by klaurent Caltech

Kavli Affiliate: Dimitri Mawet| Summary:Measuring the chemical and isotopic compositions of gas giants and brown dwarfs provides insights into their formation pathways and birth environments. 2MASS J0249-0557 c is an L2-type planetary mass companion ($sim 12 M_mathrmJup$) orbiting a pair of brown dwarfs in the $β$ Pictoris young moving group. Its mass places it at […]


Continue.. Chemistry and Isotope Ratios of Substellar Atmospheres in the $β$ Pictoris Young Moving Group

Discovery of Quasar Variability and Early Accretion Disk Signatures at Cosmic Dawn

Posted by klaurent MIT

Kavli Affiliate: Erin Kara | Summary:In the nearby universe, quasars are well known to exhibit variability in their brightness over time, offering a powerful tool to probe the physics of accretion onto the SMBH and directly measure the mass of the SMBH. However, detecting variability in early quasars remains challenging. Here, we report the detection […]


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$4times3$ Point Correlation Functions in Galaxy Surveys: Impact of Baryonic Feedback

Posted by klaurent Chicago

Kavli Affiliate: Katrin Heitmann | Summary:We investigate the impact of baryonic feedback on two-point and three-point correlation functions (2PCFs and 3PCFs hereafter, respectively) involving galaxy density fields (g) and weak lensing shear fields (G), from simulated photometric catalogs of galaxies. Specifically, we baryonify high-resolution simulation using a baryonic correction model (BCM) and explore the consequences […]


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Upstream neutrino production and delayed jet emission in the blazar GB6 J1542+6129

Posted by klaurent Peking

Kavli Affiliate: Claudio Ricci | Summary:We investigate the physical origin and location of high-energy neutrino emission in active galactic nuclei (AGN) using the blazar GB6 J1542+6129 as a case study, testing whether neutrinos are produced in compact regions near the black hole or in parsec-scale jets. This question is central to understanding the conditions under […]


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Sparse $K$-spatial-median clustering for high-dimensional data

Posted by klaurent Peking

Kavli Affiliate: Feng Long| Summary: We propose a robust clustering framework for high-dimensional data with heavy tails and a large fraction of irrelevant variables. The method replaces the mean updates of Lloyd’s $K$-means with emphspatial medians to enhance robustness. For the assignment step, it admits either a Euclidean rule for computational simplicity or a robust […]


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Random Polarization Position Angle Behaviors across Bursts of Repeating Fast Radio Bursts

Posted by klaurent Peking

Kavli Affiliate: Kejia Lee | Summary:Fast radio bursts (FRBs), highly polarized, mostly have a nearly constant polarization position angle (PA) during each burst. Their PAs are observed to vary from burst to burst, with the statistical properties remaining stable across different observation sessions. We found that the intrinsic PAs of repeating FRBs are approximately Gaussian […]


Continue.. Random Polarization Position Angle Behaviors across Bursts of Repeating Fast Radio Bursts