Search Publications
The Global Implications of the Hard Excess. II. Analysis of the Local Population of Radio-quiet AGNs
Turner, T. J.; Reeves, J. N.; Gofford, J. +5 more
Active galactic nuclei (AGNs) show evidence for reprocessing gas, outflowing from the accreting black hole. The combined effects of absorption and scattering from the circumnuclear material likely explain the “hard excess” of X-ray emission above 20 keV, compared with the extrapolation of spectra from lower X-ray energies. In a recent Suzaku study…
Evidence for a Very Low-column Density Hole in the Galactic Halo in the Direction of the High Latitude Molecular Cloud MBM 16
Liu, W.; Galeazzi, M.; Ursino, E.
Shadow observations are the only way to observe emission from the galactic halo (GH) and/or the circumgalactic medium (CGM) free of any foreground contamination from local hot bubble (LHB) and solar wind charge exchange (SWCX). We analyzed data from a shadow observation in the direction of the high latitude, neutral hydrogen cloud MBM 16 with Suza…
Inferring the Coronal Density Irregularity from EUV Spectra
Hahn, M.; Savin, D. W.
Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present a new method for quantifying such structures using density-sensitive extreme ultraviolet line intensities to…
The Intragroup versus the Intracluster Medium
Lapi, A.; Cavaliere, A.; Fusco-Femiano, R.
Galaxy groups differ from clusters primarily by way of their lower masses, M ∼ 1014 M ⊙ versus M ∼ 1015 M ⊙. We discuss how mass affects the thermal state of the intracluster or the intragroup medium, specifically as to their entropy levels and radial profiles. We show that entropy is produced in both ca…
Detecting Planet Pairs in Mean Motion Resonances via the Astrometry Method
Zhang, Hui; Zhou, Ji-Lin; Liu, Hui-Gen +2 more
Gaia is leading us into a new era with a high astrometry precision of ∼10 µas. Under such precision, astrometry can play an important role in detecting and characterizing exoplanets. In particular, we can identify planet pairs in mean motion resonances (MMRs), which constrain the formation and evolution of planetary systems. In accordance wi…
AKARI Near-infrared Spectroscopy of the Extended Green Object G318.05+0.09: Detection of CO Fundamental Ro-vibrational Emission
Onaka, Takashi; Sakon, Itsuki; Mori, Tamami +1 more
We present the results of near-infrared (2.5-5.4 µm) long-slit spectroscopy of the extended green object (EGO) G318.05+0.09 with AKARI. Two distinct sources are found in the slit. The brighter source has strong red continuum emission with H2O ice, CO2 ice, and CO gas and ice absorption features at 3.0, 4.25 µm, 4.…
Disentangling AGN and Star Formation Activity at High Redshift Using Hubble Space Telescope Grism Spectroscopy
Trump, Jonathan R.; Schneider, Donald P.; Gronwall, Caryl +4 more
Differentiating between active galactic nucleus (AGN) activity and star formation in z ∼ 2 galaxies is difficult because traditional methods, such as line-ratio diagnostics, change with redshift, while multi-wavelength methods (X-ray, radio, IR) are sensitive to only the brightest AGNs. We have developed a new method for spatially resolving emissi…
Narrow-line X-Ray-selected Galaxies in the Chandra-COSMOS Field. I. Optical Spectroscopic Catalog
Civano, F.; Elvis, M.; Watson, M. G. +1 more
The COSMOS survey is a large and deep survey with multiwavelength observations of sources from X-rays to the UV, allowing an extensive study of their properties. The central 0.9 deg2 of the COSMOS field have been observed by Chandra with a sensitivity up to 1.9 × 10-16 erg cm-2 s-1 in the full (0.5-10 ke…
Coronal Dynamic Activities in the Declining Phase of a Solar Cycle
Choe, G. S.; Woods, T. N.; Jang, Minhwan +1 more
It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar cycle, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot cycle by examining the evolution of polar and low-latitude coronal hole (CH) area…
A Robust Measure of Dark Matter Halo Ellipticities
Evslin, Jarah
In simulations of the standard cosmological model (ΛCDM), dark matter halos are aspherical. However, so far the asphericity of an individual galaxy’s halo has never been robustly established. We use the Jeans equations to define a quantity that robustly characterizes a deviation from rotational symmetry. This quantity is essentially the gravitatio…