Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/mds.29838 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
JWST sighting of decameter main-belt asteroids and view on meteorite sources.
Nature
December 2024
Max-Planck-Institut für Astronomie, Heidelberg, Germany.
Asteroid discoveries are essential for planetary-defense efforts aiming to prevent impacts with Earth, including the more frequent megaton explosions from decameter impactors. While large asteroids (≥100 km) have remained in the main belt since their formation, small asteroids are commonly transported to the near-Earth object (NEO) population. However, due to the lack of direct observational constraints, their size-frequency distribution -which informs our understanding of the NEOs and the delivery of meteorite samples to Earth-varies significantly among models.
View Article and Find Full Text PDFSupernova Axions Convert to Gamma Rays in Magnetic Fields of Progenitor Stars.
Phys Rev Lett
November 2024
Berkeley Center for Theoretical Physics, University of California, Berkeley, California 94720, USA and Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
It has long been established that axions could have been produced within the nascent proto-neutron star formed following the type II supernova SN1987A, escaped the star due to their weak interactions, and then converted to gamma rays in the Galactic magnetic fields; the nonobservation of a gamma-ray flash coincident with the neutrino burst leads to strong constraints on the axion-photon coupling for axion masses m_{a}≲10^{-10} eV. In this Letter, we use SN1987A to constrain higher mass axions, all the way to m_{a}∼10^{-3} eV, by accounting for axion production from the Primakoff process, nucleon bremsstrahlung, and pion conversion along with axion-photon conversion on the still-intact magnetic fields of the progenitor star. Moreover, we show that gamma-ray observations of the next Galactic supernova, leveraging the magnetic fields of the progenitor star, could detect quantum chromodynamics axions for masses above roughly 50 μeV, depending on the supernova.
View Article and Find Full Text PDFAccelerated formation of ultra-massive galaxies in the first billion years.
Nature
November 2024
School of Physics, University of Melbourne, Parkville, Victoria, Australia.
Article Synopsis
- Recent observations from the James Webb Space Telescope (JWST) have found many massive-galaxy candidates in the early Universe, stretching further back in time and at lower brightness levels than previously seen.
- These findings initially posed challenges to the Λ cold dark-matter model, but the new study's results show no significant conflicts when accounting for spectroscopic redshifts.
- The research highlights three ultra-massive galaxies that convert a notably high percentage of baryons into stars, suggesting they play a significant role in cosmic star-formation rates at redshifts 5 to 6.
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Surveying the distant Universe.
Open Res Eur
June 2024
Institute of Theoretical Astrophysics, University of Oslo, Oslo, N-0315, Norway.
During the most active period of star formation in galaxies, which occurs in the redshift range 1 3, strong bursts of star formation result in significant quantities of dust, which obscures new stars being formed as their UV/optical light is absorbed and then re-emitted in the infrared, which redshifts into the mm/sub-mm bands for these early times. To get a complete picture of the high- galaxy population, we need to survey a large patch of the sky in the sub-mm with sufficient angular resolution to resolve all galaxies, but we also need the depth to fully sample their cosmic evolution, and therefore obtain their redshifts using direct mm spectroscopy with a very wide frequency coverage. This requires a large single-dish sub-mm telescope with fast mapping speeds at high sensitivity and angular resolution, a large bandwidth with good spectral resolution and multiplex spectroscopic capabilities.
View Article and Find Full Text PDFA deep investigation of the poorly studied open cluster King 18 using CCD VRI, Gaia DR3 and 2MASS.
Sci Rep
October 2024
National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, 11421, Egypt.
In this paper, we re-estimate the astrometric and photometric parameters of the young open star cluster King 18 based on Gaia Data Release 3 (DR3), Two Micron All-sky Survey (2MASS) and VRI CCD observations using the f/4.9 Newtonian focus of 74-inch telescope at Kottamia Astronomical Observatory (KAO) in Egypt. King 18 is a poorly studied open star cluster, for which new results are found in the current study.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!