Search Publications
A Hard Look at Local, Optically Selected, Obscured Seyfert Galaxies
Kaastra, J. S.; Stern, D.; Brandt, W. N. +11 more
We study the X-ray spectra of a sample of 19 obscured, optically selected Seyfert galaxies (Sy 1.8, 1.9, and 2) in the local universe (d ≤ 175 Mpc), drawn from the CfA Seyfert sample. Our analysis is driven by the high sensitivity of NuSTAR in the hard X-rays, coupled with soft X-ray spectra using XMM-Newton, Chandra, Suzaku, and Swift/XRT. We als…
Direct Measurement of the Solar-wind Taylor Microscale Using MMS Turbulence Campaign Data
Strangeway, Robert J.; Russell, Christopher T.; Chasapis, Alexandros +7 more
Using the novel Magnetospheric Multiscale (MMS) mission data accumulated during the 2019 MMS Solar Wind Turbulence Campaign, we calculate the Taylor microscale (λT) of the turbulent magnetic field in the solar wind. The Taylor microscale represents the onset of dissipative processes in classical turbulence theory. However, an accurate e…
Diagonal Ridge Pattern of Different Age Populations Found in Gaia-DR2 with LAMOST Main-sequence Turnoff and OB-type Stars
Wang, H. -F.; López-Corredoira, M.; Huang, Y. +5 more
We revisit the diagonal ridge feature (diagonal distributions in the R, vφ plane) found in Gaia and present a timing analysis for it between Galactocentric distances of R = 7.5 and 12 kpc, using main-sequence turnoff and OB stars selected from the LAMOST Galactic spectroscopic surveys. We recover the ridge pattern in the R-vφ…
Dependence of the IRX-β Dust Attenuation Relation on Metallicity and Environment
Shivaei, Irene; Mobasher, Bahram; Scoville, Nick +4 more
We use a sample of star-forming field and protocluster galaxies at z = 2.0-2.5 with Keck/MOSFIRE K-band spectra, a wealth of rest-frame ultraviolet (UV) photometry, and Spitzer/MIPS and Herschel/PACS observations, to dissect the relation between the ratio of infrared (IR) to UV luminosity (IRX) versus UV slope (β) as a function of gas-phase metall…
A Massive Molecular Torus inside a Gas-poor Circumnuclear Disk in the Radio Galaxy NGC 1052 Discovered with ALMA
Kohno, Kotaro; Terashima, Yuichi; Nakai, Naomasa +7 more
We report ALMA observations of NGC 1052 to search for mass accretion in a gas-poor active galactic nucleus. We detected CO emission representing a rotating ring-like circumnuclear disk (CND) seen edge-on with a gas mass of 5.3 × 105 M⊙. The CND has smaller gas mass than that in typical Seyfert galaxies with circumnuclear star…
TOI-1728b: The Habitable-zone Planet Finder Confirms a Warm Super-Neptune Orbiting an M-dwarf Host
Cochran, William D.; Endl, Michael; Mahadevan, Suvrath +23 more
We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder. TOI-1728 is an old, inactive M0 star with Teff = ${3980}_{-32}^{+31}$ K, which hosts a transiting super-Neptune at an orbital period of ∼3.49 days. Joint f…
HD 62542: Probing the Bare, Dense Core of a Translucent Interstellar Cloud
York, Donald G.; Welty, Daniel E.; Snow, Theodore P. +1 more
We discuss the interstellar absorption from many atomic and molecular species seen in high-resolution Hubble Space Telescope/STIS UV and high signal-to-noise ratio optical spectra of the moderately reddened B3-5 V star HD 62542. This remarkable sight line exhibits both very steep far-UV extinction and a high fraction of hydrogen in molecular form,…
Is Extended Hard X-Ray Emission Ubiquitous in Compton-thick AGN?
Elvis, Martin; Risaliti, Guido; Fabbiano, G. +4 more
The recent Chandra discovery of extended ∼kiloparsec-scale hard (>3 keV) X-ray emission in nearby Compton-thick (CT) active galactic nuclei (AGN) opens a new window to improving AGN torus modeling and investigating how the central supermassive black hole interacts with and impacts the host galaxy. Since there are only a handful of detections so…
Inverse First Ionization Potential Effects in Giant Solar Flares Found from Earth X-Ray Albedo with Suzaku/XIS
Maeda, Yoshitomo; Katsuda, Satoru; Sato, Kosuke +21 more
We report X-ray spectroscopic results for four giant solar flares that occurred on 2005 September 7 (X17.0), 2005 September 8 (X5.4), 2005 September 9 (X6.2), and 2006 December 5 (X9.0), obtained from Earth albedo data with the X-ray Imaging Spectrometer (XIS) on board Suzaku. The good energy resolution of the XIS (FWHM ∼ 100 eV) enables us to sep…
Magnetosheath Jets and Plasmoids: Characteristics and Formation Mechanisms from Hybrid Simulations
Blanco-Cano, Xóchitl; Burgess, David; Trotta, Domenico +2 more
Magnetosheath jets and plasmoids are very common phenomena downstream of Earth's quasi-parallel bow shock. As the increase of the dynamic pressure is one of the principal characteristics of magnetosheath jets, the embedded paramagnetic plasmoids have been considered as an special case of the former. Although the properties of both types of structu…