Related papers: Revisiting the axion bounds from the Galactic whit…
Studies of Fermi-Large Area Telescope (LAT) data coincident with dwarf spheroidal satellite galaxies (dSphs) of the Milky Way (MW) have put the most stringent constraints on models of annihilating dark matter (DM) with candidate masses in…
Infrared excess is an important probe of sub-stellar companions and/or debris disks around white dwarfs (WDs). Such systems are still rare for in-depth understanding of their formation and long-term evolution. One of the largest…
Our knowledge of the magnetism in white dwarfs is based on an observational dataset that is biased in favour of stars with very strong magnetic fields. Most of the field measurements available in the literature have a relatively low…
Using the SDSS DR7 spectroscopic catalog, we searched the WISE AllWISE catalog to investigate the occurrence of warm dust, as inferred from IR excesses, around field M dwarfs (dMs). We developed SDSS/WISE color selection criteria to…
We present the results of a search for bright (-22.7 < M_UV < -20.5) Lyman-break galaxies at z ~ 6 within a total of 1.65 square degrees of imaging in the UltraVISTA/COSMOS and UKIDSS UDS/SXDS fields. The deep near-infrared imaging…
Warm Dark Matter (WDM) has been invoked to resolve apparent conflicts of Cold Dark Matter (CDM) models with observations on subgalactic scales. In this work we provide a new and independent lower limit for the WDM particle mass (e.g.…
We present the results of a search for deeply-eclipsing white dwarfs in the ZTF Data Release 4. We identify nine deeply-eclipsing white dwarf candidates, four of which we followed up with high-cadence photometry and spectroscopy. Three of…
We obtain R-band photometry for galaxies in six nearby poor groups for which we have spectroscopic data, including 328 new galaxy velocities. For the five groups with luminous X-ray halos, the composite group galaxy luminosity function…
We present spatially resolved kinematic measurements of AGN-driven outflows in dwarf galaxies in the stellar mass range $\sim6\times10^8 - 9\times10^9 M_\odot$, selected from SDSS DR7,8 and followed up with Keck/LRIS spectroscopy. We find…
White dwarf main-sequence (WDMS) binaries provide important laboratories for studying binary evolution and the formation of low-mass white dwarfs. In this work, we identify 654 reliable WDMS candidates with FGK-type companions from an…
In an edge-on and detached binary system, including a white dwarf (WD) and a main-sequence star (WDMS), when the source star is passing behind the compact companion its light is bent and magnified. Meanwhile, some part of its images' area…
We review the physics case for very weakly coupled ultralight particles beyond the Standard Model, in particular for axions and axion-like particles (ALPs): (i) the axionic solution of the strong CP problem and its embedding in well…
We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 Mo for our sample, with a dispersion of only 0.09 Mo. White…
We report a broad-band analysis of a Galactic X-ray source, CXOGBS J174517.0-321356 (J1745), with a 614-second periodicity. Chandra discovered the source in the direction of the Galactic Bulge. Gong (2022) proposed J1745 was either an…
The advancement of astronomical observations opens the possibility of testing our current understanding of gravitational theory in the strong-field regime and probing any deviation from general relativity. We explore to what extent compact…
Compact objects such as neutron stars and white dwarfs can source axion-like particles and QCD axions due to CP-violating axion-fermion couplings. The magnitude of the axion field depends on the stellar density and on the strength of the…
White dwarfs (WDs), as the remnants of low to intermediate-mass stars, provide a unique opportunity to explore the interplay between quantum mechanical degeneracy pressure and gravitational forces under extreme conditions. In this study, we…
Numerical simulations suggest that merging double white dwarfs (WDs) may produce a newborn neutron star surrounded by a fossil disk. We investigate the evolution of the fossil disk following the coalescence of double WDs. We demonstrate…
We study a sample of about 1400 disk M dwarfs that are found in 148 fields observed with the Wide Field Camera 2 (WFC2) on the Hubble Space Telescope and 162 fields observed with pre-repair Planetary Camera 1 (PC1), of which 95 of the WFC2…
Axions are hypothetical particles proposed to solve the strong CP problem in QCD and may constitute a significant fraction of the dark matter in the Universe. Axions are expected to be produced in neutron stars and subsequently decay,…