Search Publications
Long-term X-ray Changes in the Emission from the Anomalous X-ray Pulsar 4U 0142+61
Gonzalez, M. E.; Kaspi, V. M.; Woods, P. M. +3 more
We present results obtained from X-ray observations of the anomalous X-ray pulsar (AXP) 4U 0142+61 taken between 2000 and 2008 using XMM-Newton, Chandra, and Swift. These observations coincide with periods of long-term changes and burst epochs previously reported using the Rossi X-ray Timing Explorer (RXTE). In observations taken before 2006, we f…
Constraining the Outburst Properties of the SMBH in Fornax A Through X-ray, Infrared, and Radio Observations
Jones, Christine; Ashby, Matthew L. N.; Kraft, Ralph +3 more
Combined Spitzer, Chandra, XMM-Newton, and VLA observations of the giant radio galaxy NGC 1316 (Fornax A) show a radio jet and X-ray cavities from active galactic nucleus (AGN) outbursts most likely triggered by a merger with a late-type galaxy at least 0.4 Gyr ago. We detect a weak nucleus with a spectral energy distribution typical of a low-lumi…
Witnessing the Key Early Phase of Quasar Evolution: An Obscured Active Galactic Nucleus Pair in the Interacting Galaxy IRAS 20210+1121
Maiolino, Roberto; Nicastro, Fabrizio; Fiore, Fabrizio +6 more
We report the discovery of an active galactic nucleus (AGN) pair in the interacting galaxy system IRAS 20210+1121 at z = 0.056. An XMM-Newton observation reveals the presence of an obscured (N H ~ 5 × 1023 cm-2), Seyfert-like (L 2-10 keV = 4.7 × 1042 erg s-1) nucleus in the northern…
Non-Maxwellian Hα Profiles in Tycho's Supernova Remnant
Blair, William P.; Lee, Jae-Joon; Raymond, John C. +2 more
The broad components of the Hα lines in most non-radiative shocks can be fit with single-Gaussian components. We have obtained a high-quality spectrum of a position in Tycho's supernova remnant with the MMT and Blue Channel Spectrograph which shows, for the first time, that a single Gaussian does not provide an acceptable fit. This implies that a …
The Blue Hook Populations of Massive Globular Clusters
Brown, Thomas M.; Hubeny, Ivan; Sweigart, Allen V. +3 more
We present new Hubble Space Telescope ultraviolet color-magnitude diagrams of five massive Galactic globular clusters: NGC 2419, NGC 6273, NGC 6715, NGC 6388, and NGC 6441. These observations were obtained to investigate the "blue hook" (BH) phenomenon previously observed in UV images of the globular clusters ω Cen and NGC 2808. Blue hook stars ar…
Resolved Shock Structure of the Balmer-dominated Filaments in Tycho's Supernova Remnant: Cosmic-ray Precursor?
Blair, William P.; Lee, Jae-Joon; Raymond, John C. +4 more
We report on the results from Hα imaging observations of the eastern limb of Tycho's supernova remnant (SN1572) using the Wide Field Planetary Camera 2 on the Hubble Space Telescope. We resolve the detailed structure of the fast, collisionless shock wave into a delicate structure of nearly edge-on filaments. We find a gradual increase of Hα intens…
On the X-Ray Spectra of Anomalous X-Ray Pulsars and Soft Gamma Repeaters
Kaspi, V. M.; Boydstun, K.
We revisit the apparent correlation between soft X-ray band photon index and spin-down rate \dot{ν} previously reported for Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) by Marsden & White. Our analysis, improved thanks to new source discoveries, better spectral parameter measurements in previously known sources, and the requi…
Cosmic-ray-mediated Formation of Benzene on the Surface of Saturn's Moon Titan
Liang, Mao-Chang; Yung, Yuk L.; Kaiser, Ralf I. +4 more
The aromatic benzene molecule (C6H6)—a central building block of polycyclic aromatic hydrocarbon molecules—is of crucial importance for the understanding of the organic chemistry of Saturn's largest moon, Titan. Here, we show via laboratory experiments and electronic structure calculations that the benzene molecule can be for…
Emergence of Helical Flux and the Formation of an Active Region Filament Channel
Kubo, M.; Lites, B. W.; Title, A. +6 more
We present comprehensive observations of the formation and evolution of a filament channel within NOAA Active Region (AR) 10978 from Hinode/Solar Optical Telescope and TRACE. We employ sequences of Hinode spectro-polarimeter maps of the AR, accompanying Hinode Narrowband Filter Instrument magnetograms in the Na I D1 line, Hinode Broadband Filter I…
X-ray Pulsations from the Radio-quiet Gamma-ray Pulsar in CTA 1
Caraveo, P. A.; Bignami, G. F.; Marelli, M. +4 more
Prompted by the Fermi-LAT discovery of a radio-quiet gamma-ray pulsar inside the CTA 1 supernova remnant, we obtained a 130 ks XMM-Newton observation to assess the timing behavior of this pulsar. Exploiting both the unprecedented photon harvest and the contemporary Fermi-LAT timing measurements, a 4.7σ single-peak pulsation is detected, making PSR…