Joel Leja

Nov 6, 2024 | nature.com | Kritti Sharma |Stella Ocker |Myles Sherman |Gregg Hallinan |James Lamb |Joel Leja | +4 more

AbstractFast radio bursts (FRBs) are millisecond-duration events detected from beyond the Milky Way. FRB emission characteristics favour highly magnetized neutron stars, or magnetars, as the sources1, as evidenced by FRB-like bursts from a galactic magnetar2,3, and the star-forming nature of FRB host galaxies4,5. However, the processes that produce FRB sources remain unknown6.

Jun 26, 2024 | iopscience.iop.org | Bingjie Wang |Joel Leja |Anna de Graaff |Max-Planck-Institut für Astronomie

In the cores of the most massive galaxies in the local Universe, stars have inferred stellar age of ∼13 Gyr and high α-element abundance, suggesting that their stellar components are formed at z ≳ 5 in a spectacular and short burst of star formation (e.g., Thomas et al. 2005).

Feb 14, 2024 | nature.com | Lukas J. Furtak |Ivo Labbe |Adi Zitrin |Anna de Graaff |Rachel Bezanson |Gabriel Brammer | +14 more

AbstractEarly JWST observations have uncovered a new population of red sources that might represent a previously overlooked phase of supermassive black hole growth1−−3. One of the most intriguing examples is an extremely red, point-like object that was found to be triply-imaged by the strong lensing (SL) cluster Abell 27444. Here we present deep JWST/NIRSpec observations of this object, Abell2744-QSO1.

Feb 22, 2023 | inkl.com | Joel Leja

Using the first data released from Nasa’s James Webb Space Telescope (JWST) last July, the scientists found objects as mature as the Milky Way when the universe was only 3% of its current age – some 500-700 million years after the Big Bang. Joel Leja, assistant professor of astronomy and astrophysics at Penn State University, America, said: “These objects are way more massive​ than anyone expected.