Search Publications
New Velocity Measurements of NGC 5128 Globular Clusters Out to 130 kpc: Outer Halo Kinematics, Substructure, and Dynamics
Forbes, Duncan A.; Caldwell, Nelson; Strader, Jay +11 more
We present new radial velocity measurements from the Magellan and the Anglo-Australian Telescopes for 175 previously known and 121 newly confirmed globular clusters (GCs) around NGC 5128, the nearest accessible massive early-type galaxy at D = 3.8 Mpc. Remarkably, 28 of these newly confirmed GCs are at projected radii $\gt 50^{\prime} $ (≳54 kpc),…
A Recipe for Unbiased Background Modeling in Deep Wide-field Astronomical Images
van Dokkum, Pieter; Abraham, Roberto; Pasha, Imad +9 more
Unbiased sky background modeling is crucial for the analysis of deep wide-field images, but it remains a major challenge in low surface brightness astronomy. Traditional image processing algorithms are often designed to produce artificially flat backgrounds, erasing astrophysically meaningful structures. In this paper, we present three ideas that …
Reference frames in general relativity and the galactic rotation curves
Frutos-Alfaro, F.; Costa, L. Filipe O.; Natário, José +1 more
The physical interpretation of the exact solutions of the Einstein field equations is, in general, a challenging task, part of the difficulties lying in the significance of the coordinate system. We discuss the extension of the International Astronomical Union (IAU) reference system to the exact theory. It is seen that such an extension, retaining…
A Data-driven, Physics-based Transport Model of Solar Energetic Particles Accelerated by Coronal Mass Ejection Shocks Propagating through the Solar Coronal and Heliospheric Magnetic Fields
Riley, Pete; Zhang, Ming; Lario, David +5 more
In an effort to develop computational tools for predicting radiation hazards from solar energetic particles (SEPs), we have created a data-driven physics-based particle transport model to calculate the injection, acceleration, and propagation of SEPs from coronal mass ejection (CME) shocks traversing through the solar corona and interplanetary mag…
The most luminous, merger-free AGNs show only marginal correlation with bar presence
Coil, Alison; Keel, William C.; Simmons, Brooke D. +13 more
The role of large-scale bars in the fuelling of active galactic nuclei (AGNs) is still debated, even as evidence mounts that black hole growth in the absence of galaxy mergers cumulatively dominates and may substantially influence disc (i.e. merger-free) galaxy evolution. We investigate whether large-scale galactic bars are a good candidate for me…
Crossing the Rubicon of Reionization with z 5 QSOs
Grazian, Andrea; Boutsia, Konstantina; Fiore, Fabrizio +12 more
One of the key open questions in cosmology is the nature of sources that completed cosmological hydrogen reionization at z ~ 5.2. High-z primeval galaxies have been long considered the main drivers of reionization, with a minor role played by high-z active galactic nuclei (AGN). However, in order to confirm this scenario, it is fundamental to meas…
Recurring outbursts of the supernova impostor AT 2016blu in NGC 4559
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Smith, Nathan +8 more
We present the first photometric analysis of the supernova (SN) impostor AT 2016blu in NGC 4559. This transient was discovered by the Lick Observatory Supernova Search in 2012 and has continued its outbursts since then. Optical and infrared photometry of AT 2016blu reveals at least 19 outbursts in 2012-2022. Similar photometry from 1999 to 2009 sh…
Revisiting empirical solar energetic particle scaling relations. I. Solar flares
Veronig, Astrid M.; Papaioannou, Athanasios; Herbst, Konstantin +3 more
Aims: The possible influence of solar superflares on the near-Earth space radiation environment are assessed through the investigation of scaling laws between the peak proton flux and fluence of solar energetic particle (SEP) events with the solar flare soft X-ray peak photon flux.
Methods: We compiled a catalog of 65 well-connected (W20…
Characterization and dynamics of the peculiar stream Jhelum. A tentative role for the Sagittarius dwarf galaxy
Helmi, Amina; Woudenberg, Hanneke C.; Balbinot, Eduardo +1 more
Context. Stellar streams are a promising tool to study the Milky Way's dark matter subhalo population, as interactions with subhalos are expected to leave visible imprints in the streams in the form of substructure. However, there may be other causes of substructure.
Aims: Here we studied the kinematics and the unusual morphology of the stell…
Compact [C II] emitters around a C IV absorption complex at redshift 5.7
Simcoe, Robert A.; Kashino, Daichi; Eilers, Anna-Christina +4 more
The physical conditions of the circumgalactic medium are investigated by means of intervening absorption-line systems in the spectrum of background quasi-stellar objects (QSOs) out to the epoch of cosmic reionization1-4. A correlation between the ionization state of the absorbing gas and the nature of the nearby galaxies has been sugges…