Search Publications
Morphology of Solar Type II Bursts Caused by Shock Propagation through Turbulent and Inhomogeneous Coronal Plasma
Koval, Artem; Stanislavsky, Aleksander; Konovalenko, Aleksander +4 more
Type II solar bursts are radio signatures of shock waves in the solar corona driven by solar flares or coronal mass ejections (CMEs). Therefore, these bursts present complex spectral morphologies in solar dynamic spectra. Here, we report meter-decameter radio observations of a type II burst on 2014 July 25 made with the Ukrainian radio telescopes …
Solar Coronal Density Turbulence and Magnetic Field Strength at the Source Regions of Two Successive Metric Type II Radio Bursts
Kumari, Anshu; Ramesh, R.; Kathiravan, C.
We report spectral and polarimeter observations of two weak, low-frequency (≈85-60 MHz) solar coronal type II radio bursts that occurred on 2020 May 29 within a time interval ≈2 minutes. The bursts had fine structures, and were due to harmonic plasma emission. Our analysis indicates that the magnetohydrodynamic shocks responsible for the first and…
CO Survey of High-z Radio Galaxies, Revisited with the Atacama Large Millimeter/submillimeter Array: Jet-Cloud Alignments and Synchrotron Brightening by Molecular Gas in the Circumgalactic Environment
Carilli, Chris; Lehnert, Matthew D.; De Breuck, Carlos +6 more
Powerful radio sources associated with supermassive black holes are among the most luminous objects in the universe, and are frequently recognized both as cosmological probes and active constituents in the evolution of galaxies. We present alignments between radio jets and cold molecular gas in the environment of distant radio galaxies, and show t…
Constraining the Systematics of (Acoustic) Wave Heating Estimates in the Solar Chromosphere
Kowalski, Adam F.; Cranmer, Steven R.; Reardon, Kevin P. +2 more
Acoustic wave heating is believed to contribute significantly to the missing energy input required to maintain the solar chromosphere in its observed state. We studied the propagation of waves above the acoustic cutoff in the upper photosphere into the chromosphere with ultraviolet and optical spectral observations interpreted through comparison w…
The Disturbed and Globular-cluster-rich Ultradiffuse Galaxy UGC 9050-Dw1
Sand, David J.; Jones, Michael G.; Fielder, Catherine E. +5 more
We investigate the ultradiffuse galaxy (UDG) UGC 9050-Dw1, which was selected because of its disturbed morphology as part of a larger sample of UDGs that display evidence for significant interactions. We use the Hubble Space Telescope's Advanced Camera for Surveys to identify globular clusters (GCs) associated with UGC 9050-Dw1, and the Jansky Ver…
Obscuring Environment and X-Ray Variability of Compact Symmetric Objects Unveiled with XMM-Newton and NuSTAR
Ostorero, Luisa; Guainazzi, Matteo; Stawarz, Łukasz +3 more
Compact symmetric objects (CSOs) show radio features such as jets, lobes, and hot spots, which are contained within their host galaxies, and likely represent a recent radio activity. A subpopulation of CSOs with high intrinsic X-ray column densities has been inferred from shallow, soft X-ray band exposures, and observed to cluster in the linear ra…
M92 (NGC 6341) Is a Metal-complex Globular Cluster with an Atypical Primordial Population
Lee, Jae-Woo
We present a multiple stellar population study of the metal-poor globular cluster (GC) M92 (NGC 6341), which is long known for the substantial metallicity dispersion, using our own photometric system. We find two groups with slightly different mean metallicities, the metal-poor (MP) stars with [Fe/H] hk = -2.412 ± 0.03 and the metal-ri…
Mapping the Decline with Redshift of Dusty Star-forming Galaxies Using JWST and SCUBA-2
Barger, A. J.; Cowie, L. L.
We use JWST NIRCam observations of the massive lensing cluster field A2744 to develop a red galaxy selection of f F444W > 1 µJy and f F444W/f F150W > 3.5 that picks out all nine >4.5σ Atacama Large Millimeter/submillimeter Array 1.1 or 1.2 mm sources and 17 of the 19 >5σ SCUBA-2 850 µm sourc…
A Statistical Study of IRIS Observational Signatures of Nanoflares and Nonthermal Particles
Polito, Vanessa; Testa, Paola; De Pontieu, Bart +1 more
Nanoflares are regarded as one of the major mechanisms of magnetic energy release and coronal heating in the solar outer atmosphere. We conduct a statistical study on the response of the chromosphere and transition region to nanoflares, as observed by the Interface Region Imaging Spectrograph (IRIS), by using an algorithm for the automatic detecti…
The Dragonfly Galaxy. III. Jet Brightening of a High-redshift Radio Source Caught in a Violent Merger of Disk Galaxies
Prochaska, J. Xavier; De Breuck, Carlos; Burchett, Joseph N. +8 more
The Dragonfly galaxy (MRC 0152-209), the most infrared-luminous radio galaxy at redshift z ~ 2, is a merger system containing a powerful radio source and large displacements of gas. We present kiloparsec-resolution data from the Atacama Large Millimeter/submillimeter Array and the Very Large Array of carbon monoxide (6-5), dust, and synchrotron co…