Search Publications
Varstrometry for Off-nucleus and Dual Sub-kiloparsec Active Galactic Nuclei (VODKA): Very Long Baseline Array Searches for Dual or Off-nucleus Quasars and Small-scale Jets
Shen, Yue; Zakamska, Nadia L.; Lazio, Joseph +5 more
Dual and off-nucleus active supermassive black holes are expected to be common in the hierarchical structure formation paradigm, but their identification at parsec scales remains a challenge due to strict angular resolution requirements. We conducted a systematic study using the Very Long Baseline Array (VLBA) to examine 23 radio-bright candidate …
Dynamical masses and ages of Sirius-like systems
Kiman, Rocio; Brandt, Timothy D.; Li, Yiting +4 more
We measure precise orbits and dynamical masses and derive age constraints for six confirmed and one candidate Sirius-like systems, including the Hyades member HD 27483. Our orbital analysis incorporates radial velocities, relative astrometry, and Hipparcos-Gaia astrometric accelerations. We constrain the main-sequence lifetime of a white dwarf's p…
Evolution of the Radial Size and Expansion of Coronal Mass Ejections Investigated by Combining Remote and In Situ Observations
Lugaz, Noé; Zhuang, Bin; Scolini, Camilla +4 more
A fundamental property of coronal mass ejections (CMEs) is their radial expansion, which determines the increase in the CME radial size and the decrease in the CME magnetic field strength as the CME propagates. CME radial expansion can be investigated either by using remote observations or by in situ measurements based on multiple spacecraft in ra…
Applying wavelet analysis to the X-ray light curves of active galactic nuclei and quasi-periodic eruptions
Gallo, L. C.; Gonzalez, A. G.; Ghosh, Akshay
In this work, we examine the application of the wavelet transform to the X-ray timing analyses of active galactic nuclei (AGN) and quasi-periodic eruption sources (QPEs). Several scenarios are simulated to test the effectiveness of the wavelet analysis to stationary and non-stationary data. We find that the power spectral density (PSD) slope and t…
Accelerated Structural Evolution of Galaxies in a Starbursting Cluster at z = 2.51
Daddi, Emanuele; Lu, Shiying; Elbaz, David +11 more
Structural properties of cluster galaxies during their peak formation epoch, z ~ 2-4 provide key information on whether and how the environment affects galaxy formation and evolution. Based on deep Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) imaging toward the z = 2.51 cluster, J1001, we explore environmental effects on the structure, …
An advanced thermal roughness model for airless planetary bodies. Implications for global variations of lunar hydration and mineralogical mapping of Mercury with the MERTIS spectrometer
Hiesinger, Harald; Helbert, Jörn; Wöhler, Christian +1 more
We present a combined reflectance and thermal radiance model for airless planetary bodies. The Hapke model provides the reflected component. The developed thermal model is the first to consistently use rough fractal surfaces, self-scattering, self-heating, and disk-resolved bolometric albedo for entire planets. We validated the model with disk-res…
The spatial correlation of high-mass X-ray binaries and young star clusters in nearby star-forming galaxies
Williams, Benjamin F.; Binder, Breanna A.; Lazzarini, Margaret +2 more
We present an analysis of the two-point spatial correlation functions of high-mass X-ray binary (HMXB) and young star cluster (YSC) populations in M31 and M33. We find evidence that HMXBs are spatially correlated with YSCs to a higher degree than would be expected from random chance in both galaxies. When supplemented with similar studies in the M…
Excitation of Saturnian ECH Waves Within Remote Plasma Injections: Cassini Observations
Ni, Binbin; Gu, Xudong; Cao, Xing +7 more
Based on Cassini observations, we report representative electrostatic electron cyclotron harmonic (ECH) wave events observed in Saturn's magnetosphere within remote plasma injections. Unlike local injections, remote injections are "older" injection events that have evolved to form a dispersed signature in particle energy spectrum. We show that Sat…
Global Energetics of Solar Powerful Events on 2017 September 6
Lu, Lei; Dresing, Nina; Wang, Jincheng +9 more
Solar flares and coronal mass ejections (CMEs) are thought to be the most powerful events on the Sun. They can release energy as high as ~1032 erg in tens of minutes, and also can release solar energetic particles (SEPs) into interplanetary space. We explore global energy budgets of solar major eruptions that occurred on 2017 September …
A LOFAR sample of luminous compact sources coincident with nearby dwarf galaxies
Shimwell, T. W.; Vedantham, H. K.; Kaplan, D. L. +5 more
The vast majority of extragalactic compact continuum radio sources are associated with star formation or jets from (super)massive black holes and, as such, are more likely to be found in association with starburst galaxies or early-type galaxies. Two new populations of radio sources were recently identified: (a) compact and persistent sources (PRS…