Search Publications
Faraday Tomography of the North Polar Spur: Constraints on the Distance to the Spur and on the Magnetic Field of the Galaxy
Leahy, J. P.; Gaensler, B. M.; McClure-Griffiths, N. M. +9 more
We present radio continuum and polarization images of the North Polar Spur (NPS) from the Global Magneto-ionic Medium Survey conducted with the Dominion Radio Astrophysical Observatory 26 m Telescope. We fit polarization angle versus wavelength squared over 2048 frequency channels from 1280 to 1750 MHz to obtain a Faraday rotation measure (RM) map…
A Measurement of the Black Hole Mass in NGC 1097 Using ALMA
Kohno, K.; Onishi, K.; Iguchi, S. +1 more
We present an estimate of the mass of the supermassive black hole (SMBH) in the nearby type-1 Seyfert galaxy NGC 1097 using Atacamma Large Millimeter/submillimeter Array (ALMA) observations of dense gas kinematics. Dense molecular gas dynamics are traced with HCN(J=1-0) and HC{{O}+}(J=1-0) emission lines. Assuming a host galaxy inclinat…
Light Bridge in a Developing Active Region. II. Numerical Simulation of Flux Emergence and Light Bridge Formation
Toriumi, Shin; Cheung, Mark C. M.; Katsukawa, Yukio
Light bridges, the bright structure dividing umbrae in sunspot regions, show various activity events. In Paper I, we reported on an analysis of multi-wavelength observations of a light bridge in a developing active region (AR) and concluded that the activity events are caused by magnetic reconnection driven by magnetconvective evolution. The aim o…
Feedback from Mass Outflows in Nearby Active Galactic Nuclei. II. Outflows in the Narrow-line Region of NGC 4151
Fischer, Travis C.; Crenshaw, D. Michael; Schmitt, Henrique R. +1 more
We present a detailed study of active galactic nucleus feedback in the narrow-line region (NLR) of the Seyfert 1 galaxy NGC 4151. We illustrate the data and techniques needed to determine the mass outflow rate (\dot{M}out) and kinetic luminosity (L KE) of the outflowing ionized gas as a function of position in the NLR. We fin…
Proper Motions and Trajectories for 16 Extreme Runaway and Hypervelocity Stars
Anderson, Jay; Bond, Howard E.; Geller, Margaret J. +3 more
We measure proper motions with the Hubble Space Telescope for 16 extreme radial velocity stars, mostly unbound B stars in the Milky Way halo. Twelve of these stars have proper motions statistically consistent with zero, and thus have radial trajectories statistically consistent with a Galactic center “hypervelocity star” origin. The trajectory of …
Propagation of the 7 January 2014 CME and Resulting Geomagnetic Non-event
Thompson, B. J.; Möstl, C.; Jian, L. K. +9 more
On 2014 January 7 an X1.2 flare and coronal mass ejection (CME) with a radial speed ≈2500 km s-1 was observed from near an active region close to disk center. This led many forecasters to estimate a rapid arrival at Earth (≈36 hr) and predict a strong geomagnetic storm. However, only a glancing CME arrival was observed at Earth with a t…
Predicting the Arrival Time of Coronal Mass Ejections with the Graduated Cylindrical Shell and Drag Force Model
Zhang, Jie; Ding, Mingde; Cheng, Xin +3 more
Accurately predicting the arrival of coronal mass ejections (CMEs) to the Earth based on remote images is of critical significance for the study of space weather. In this paper, we make a statistical study of 21 Earth-directed CMEs, specifically exploring the relationship between CME initial speeds and transit times. The initial speed of a CME is …
An Ultrasoft X-Ray Flare from 3XMM J152130.7+074916: A Tidal Disruption Event Candidate
Gwyn, Stephen D. J.; Komossa, S.; Lin, Dacheng +6 more
We report on the discovery of an ultrasoft X-ray transient source, 3XMM J152130.7+074916. It was serendipitously detected in an XMM-Newton observation on 2000 August 23, and its location is consistent with the center of the galaxy SDSS J152130.72+074916.5 (z = 0.17901 and dL = 866 Mpc). The high-quality X-ray spectrum can be fitted with…
Hard X-Ray Morphological and Spectral Studies of the Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
Hailey, Charles J.; Mori, Kaya; Bauer, Franz E. +15 more
In 2013, NuSTAR observed the Sgr B2 region and for the first time resolved its hard X-ray emission on subarcminute scales. Two prominent features are detected above 10 keV: a newly emerging cloud, G0.66-0.13, and the central 90″ radius region containing two compact cores, Sgr B2(M) and Sgr B2(N), surrounded by diffuse emission. It is inconclusive …
Evidence of Cross-correlation between the CMB Lensing and the γ-Ray Sky
Fornengo, Nicolao; Perotto, Laurence; Regis, Marco +1 more
We report the measurement of the angular power spectrum of cross-correlation between the unresolved component of the Fermi-LAT γ-ray sky maps and the cosmic microwave background lensing potential map reconstructed by the Planck satellite. The matter distribution in the universe determines the bending of light coming from the last scattering surfac…