Search Publications
Identification of Two Bright z > 3 Submillimeter Galaxy Candidates in the COSMOS Field
Capak, P.; Espada, D.; Fazio, G. G. +5 more
We present high-resolution interferometric Submillimeter Array imaging at 890 µm (~2'' resolution) of two millimeter selected galaxies—MMJ100015+021549 and MMJ100047+021021—discovered with the Max-Planck Millimeter Bolometer (MAMBO) on the IRAM 30 m telescope and also detected with Bolocam on the CSO, in the COSMOS field. The first source is…
Empirical Delay-time Distributions of Type Ia Supernovae from the Extended Goods/Hubble Space Telescope Supernova Survey
Riess, Adam G.; Strolger, Louis-Gregory; Dahlen, Tomas
Using the Hubble Space Telescope (HST) Advanced Camera for Surveys imaging of the GOODS North and South fields during Cycles 11, 12, and 13, we derive empirical constraints on the delay-time distribution function for type Ia supernovae (SNe Ia). We extend our previous analysis to the three-year sample of 56 SNe Ia over the range 0.2 < z < 1.…
Suzaku Observations of Luminous Quasars: Revealing the Nature of High-energy Blazar Emission in Low-level Activity States
Maraschi, L.; Ozaki, M.; Frailis, M. +171 more
We present the results from the Suzaku X-ray observations of five flat-spectrum radio quasars (FSRQs), namely PKS 0208-512, Q 0827+243, PKS 1127-145, PKS 1510-089, and 3C 454.3. All these sources were additionally monitored simultaneously or quasi-simultaneously by the Fermi satellite in gamma rays and the Swift UVOT in the UV and optical bands, r…
Suzaku Monitoring of the Iron K Emission Line in the Type 1 Active Galactic Nucleus NGC 5548
Elvis, Martin; Wilkes, Belinda J.; Nicastro, Fabrizio +10 more
We present seven sequential weekly observations of NGC 5548 conducted in 2007 with the Suzaku X-ray Imaging Spectrometer (XIS) in the 0.2-12 keV band and Hard X-ray Detector (HXD) in the 10-600 keV band. The iron Kα line is well detected in all seven observations and Kβ line is also detected in four observations. In this paper, we investigate the …
Long-term Multi-wavelength Studies of GRS 1915+105. I. A High-energy and Mid-infrared Focus with RXTE/INTEGRAL and Spitzer
Chaty, S.; Rahoui, F.; Rodriguez, J. +3 more
To date, mid-infrared properties of Galactic black hole binaries have barely been investigated in the framework of multi-wavelength campaigns. Yet, studies in this spectral domain are crucial to get complementary information on the presence of dust and/or on the physical processes such as dust heating and thermal bremsstrahlung. Here, we report a …
Coronal Mass Ejections and Sunspots—Solar Cycle Perspective
Ramesh, K. B.
Recent studies have indicated that the occurrence of the maxima of coronal mass ejection (CME) rate and sunspot number (SSN) were nearly two years apart. We find that the two-year lag of CME rate manifests only when the SSN index is considered and the lag is minimal (two-three months) when the sunspot area is considered. CMEs with speeds greater t…
A Hemispheric Helicity Sign Rule Indicated by Large-scale Photospheric Magnetic Fields at Three Phases of Solar Cycle 23
Zhang, Mei; Wang, Chuanyu
The hemispheric sign rule of current helicity is examined for large-scale magnetic fields, extending to 60° high in solar latitudes, at three different phases of solar cycle 23 and using three different instruments. The current helicity is calculated from the vector magnetic fields derived respectively from the longitudinal full-disk magnetograms …
Remarkable Spectral Variability of PDS 456
Kaspi, Shai; Turner, T. J.; O'Brien, Paul T. +3 more
We report on the highest to date signal-to-noise ratio X-ray spectrum of the luminous quasar PDS 456, as obtained during two XMM-Newton orbits in 2007 September. The present spectrum is considerably different from several previous X-ray spectra recorded for PDS 456 since 1998. The ultra-high-velocity outflow seen as recently as 2007 February is no…
NICMOS Observations of the Transiting Hot Jupiter XO-1b
Valenti, Jeff A.; Nelan, Edmund P.; Johns-Krull, Christopher M. +6 more
We refine the physical parameters of the transiting hot Jupiter planet XO-1b and its stellar host XO-1 using Hubble Space Telescope (HST) NICMOS observations. XO-1b has a radius Rp = 1.21 ± 0.03 RJ , and XO-1 has a radius R sstarf = 0.94 ± 0.02 R sun, where the uncertainty in the mass of XO-1 dominates t…
Investigation of Chromospheric Evaporation in a Neupert-type Solar Flare
Cao, Wenda; Ning, Zongjun
The Neupert effect implies a flare model in which the hard X-rays (HXRs) are produced by energetic electrons via electron-ion bremsstrahlung as they lose their energies in the chromosphere, while the soft X-rays (SXRs) are produced by thermal bremsstrahlung from "chromospheric evaporation" due to plasma being heated by those same electrons. Based …