May 2025 (Page 9)

Discovery of the binary nature of the magnetospheric B-type star $rho$ Oph A M. E. Shultz, I. Berry, D. Bohlender, G. Catanzaro, M. Giarrusso, R. Klement, J. Labadie-Bartz, F. Leone, P. Leto, C. Neiner, S. P. Owocki, Th. Rivinius, A. ud-Doula, G. A. Wade arXiv:2505.08007v2 Announce Type: replace Abstract: The nearby B-type star $rho$ Oph A was recently identified as a rapidly rotating magnetic B-type star with variable radio and X-ray emission consistent with a magnetospheric origin. We present a high-resolution spectropolarimetric time series obtained with ESPaDOnS, which we use to perform a magnetic analysis using least-squares deconvolution (LSD). We find that $rho$ Oph ARead More →

Intermingled open and closed magnetic field lines near the radial origin of the heliospheric current sheet Forrest Mozer, Andrii Voshchepynets, Oleksiy Agapitov, Kyung-Eu Choi, Richard Sydora arXiv:2501.08419v2 Announce Type: replace Abstract: Aims. To investigate the magnetic field geometry and waves in the region near the Sun where the heliospheric current sheet is formed. Methods. One good example of apparent open and closed field lines was found and its fields and plasmas were analyzed. Results. The radial component of the magnetic field (the Z-component) measured on the Parker Solar Probe (PSP) changed sign between 12:00 and 13:00 UT on March 30, 2024, when the spacecraft wasRead More →

Where Have All the Little Red Dots Gone? Supermassive Black Hole Binary Dynamics and its Impact on Galaxy Properties Fazeel Mahmood Khan, Benjamin L. Davis, Andrea Valerio Macci`o, Kelly Holley-Bockelmann arXiv:2503.07711v2 Announce Type: replace Abstract: Recent James Webb Space Telescope observations have revealed a peculiar class of galaxies at redshifts $z gtrsim 6$, characterized by extremely high central stellar densities and overmassive central supermassive black holes (SMBHs), “little red dots” (LRDs). A critical question remains: If LRDs were common at high redshifts, how would they evolve into local elliptical galaxies with significantly lower central densities? To address this, we performed direct $N$-body simulations of LRDRead More →

Task-parallelism in SWIFT for heterogeneous compute architectures Abouzied M. A. Nasar, Benedict D. Rogers, Georgios Fourtakas, Scott T. Kay, Matthieu Schaller arXiv:2505.14538v1 Announce Type: cross Abstract: This paper highlights the first steps towards enabling graphics processing unit (GPU) acceleration of the smoothed particle hydrodynamics (SPH) solver for cosmology SWIFT and creating a hydrodynamics solver capable of fully leveraging the hardware available on heterogeneous exascale machines composed of central and graphics processing units (CPUs and GPUs). Exploiting the existing task-based parallelism in SWIFT, novel combinations of algorithms are presented which enable SWIFT to function as a truly heterogeneous software leveraging CPUs for memory-bound computations concurrently withRead More →

Fundamental constants: from measurement to the universe, a window on gravitation and cosmology Jean-Philippe Uzan arXiv:2410.07281v2 Announce Type: replace Abstract: Fundamental constants are a cornerstone of the physical laws. Any constant varying in space and/or time would signal a violation of local position invariance and be associated with a violation of the universality of free fall, and hence of the weak equivalence principle. It will reflect the existence of new degrees of freedom that couple to standard matter. Thus, testing for the stability of fundamental constants is of utmost importance for our understanding of gravity and for characterizing the domain of validity of General Relativity.Read More →

The Great Comets of 1843 and 1882 at Their Previous Return to Perihelion in the Twelfth Century: One Spectacular, the Other Dull Zdenek Sekanina arXiv:2505.14662v1 Announce Type: new Abstract: New insights into the history of C/1843 D1 and C/1882 R1, the two celebrated Kreutz sungrazers, are provided by assessing evidence on their appearance at the previous perihelion return, known as X/1106 C1 and the Chinese comet of 1138 (Ho’s No. 403), respectively. The conditions differed vastly because of disparities in geocentric distance, solar elongation, and phase correction (forward scattering), all linked to the arrival times (early February vs early August). The conclusions include: the daytimeRead More →

On the Present Status of Inflationary Cosmology Renata Kallosh, Andrei Linde arXiv:2505.13646v1 Announce Type: cross Abstract: We give a brief review of the basic principles of inflationary theory and discuss the present status of the simplest inflationary models that can describe Planck/BICEP/Keck observational data by choice of a single model parameter. In particular, we discuss the Starobinsky model, Higgs inflation, and $alpha$-attractors, including the recently developed $alpha$-attractor models with $SL(2,mathbb{Z})$ invariant potentials. We also describe inflationary models providing a good fit to the recent ACT data, as well as the polynomial chaotic inflation models with three parameters, which can account for any values of theRead More →

FAUST XXIV. Large dust grains in the protostellar outflow cavity walls of the Class I binary L1551 IRS5 G. Sabatini, E. Bianchi, C. J. Chandler, L. Cacciapuoti, L. Podio, M. J. Maureira, C. Codella, C. Ceccarelli, N. Sakai, L. Testi, C. Toci, B. Svoboda, T. Sakai, M. Bouvier, P. Caselli, N. Cuello, M. De Simone, I. J’imenez-Serra, D. Johnstone, L. Loinard, Z. E. Zhang, S. Yamamoto arXiv:2505.13596v1 Announce Type: new Abstract: Planet formation around young stars requires the growth of interstellar dust grains from mm-sized particles to km-sized planetesimals. Numerical simulations have shown that large ($sim$mm-sized) grains found in the inner envelope of young protostarsRead More →

Constraining cosmic ray transport models using circumgalactic medium properties and observables Yue Samuel Lu, Duv{s}an Kerev{s}, Philip F. Hopkins, Sam B. Ponnada, Claude-Andr’e Faucher-Gigu’ere, Cameron B. Hummels arXiv:2505.13597v1 Announce Type: new Abstract: Cosmic rays (CRs) are a pivotal non-thermal component of galaxy formation and evolution. However, the intricacies of CR physics, particularly how they propagate in the circumgalactic medium (CGM), remain largely unconstrained. In this work, we study CGM properties in FIRE-2 (Feedback In Realistic Environments) simulations of the same Milky Way (MW)-mass halo at $z=0$ with different CR transport models that produce similar diffuse $sim$ GeV $gamma$-ray emission. We study the gas morphology andRead More →

The High-redshift Blazar MG3 J163554+3629: Physical Properties and the Enigma of Its Unexpected Supermassive Black Hole Growth Jose Maria Sanchez Zaballa, Eugenio Bottacini, Andrea Tramacere arXiv:2505.13593v1 Announce Type: new Abstract: There is general consensus that active galactic nuclei (AGNs) derive their radiating power from a supermassive black hole (SMBH) that accretes matter. Yet, their precise powering mechanisms and the resulting growth of the SMBH are poorly understood, especially for AGNs at high redshift. Blazars are AGNs pointing their jet toward the observer, thus being detectable from radio through gamma rays at high redshift due to Doppler boosting. The blazar MG3 J163554+3629 is located at redshiftRead More →