Search Publications
A Population of X-Ray Weak Quasars: PHL 1811 Analogs at High Redshift
Brandt, W. N.; Hall, Patrick B.; Schneider, Donald P. +6 more
We report the results from Chandra and XMM-Newton observations of a sample of 10 type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were identified by the Sloan Digital Sky Su…
The complex circumstellar environment of HD 142527
Waters, L. B. F. M.; Pantin, E.; Dominik, C. +10 more
Context. The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD 142527, for which previous observations revealed a complex circumstellar environment and an unusually high ratio of infrared to stellar luminosity. Its properties di…
The Brightest Gamma-Ray Flaring Blazar in the Sky: AGILE and Multi-wavelength Observations of 3C 454.3 During 2010 November
Maraschi, L.; Sakamoto, T.; Pian, E. +84 more
Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all frequencies, and during the last four years it has exhibited more than one γ-ray flare per year, becoming the most active γ-ray blazar in the sky. We present for the first time the multi-wavelength AGILE, Swift, INTEGRAL, and GASP-WEBT data collected in order to explain t…
Kelvin-Helmholtz waves under southward interplanetary magnetic field
Sahraoui, F.; Parks, G. K.; Goldstein, M. L. +3 more
The Kelvin-Helmholtz waves have been observed along the Earth's low-latitude magnetopause and have been suggested to play a certain role in the entry of solar wind plasma into Earth's magnetosphere. In situ observations of the KH waves (KHW) and, in particular, a nonlinear stage of the KH instability, i.e., rolled-up KH vortices (KHVs), have been …
SMA Observations of GOODS 850-11 and GOODS 850-13: First Examples of Multiple Submillimeter Sources Resolved by an Interferometer
Williams, Jonathan P.; Wang, Wei-Hao; Cowie, Lennox L. +1 more
We carried out extremely sensitive Submillimeter Array (SMA) 340 GHz continuum imaging on two submillimeter galaxies (SMGs): GOODS 850-11 and GOODS 850-13. The observations reach sub-mJy rms sensitivities and, interestingly, resolve both sources into multiple, physically unrelated SMGs. GOODS 850-11 is resolved into two sources at different redshi…
Detection of the Cosmic Far-infrared Background in AKARI Deep Field South
Clements, D. L.; White, G. J.; Burgarella, D. +14 more
We report new limits on the absolute brightness and spatial fluctuations of the cosmic infrared background (CIB) via the AKARI satellite. We carried out observations at 65, 90, 140, and 160 µm as a cosmological survey in AKARI Deep Field South, which is one of the lowest cirrus regions with a contiguous area of the sky. After removing bright…
Study of LINER sources with broad Hα emission. X-ray properties and comparison to luminous AGN and X-ray binaries
Porquet, D.; Reeves, J. N.; Younes, G. +1 more
Context. An important number of multiwavelength studies of low ionization nuclear emission-line regions (LINERs) were dedicated to investigate the excitation mechanism responsible for the detected emission lines. Radiative emission from accretion into a super massive black hole (SMBH) is now believed to be, in an increasing number of LINERs, the s…
Age and helium content of the open cluster NGC 6791 from multiple eclipsing binary members. I. Measurements, methods, and first results
Grundahl, F.; Bedin, L. R.; Brogaard, K. +4 more
Context. Models of stellar structure and evolution can be constrained by measuring accurate parameters of detached eclipsing binaries in open clusters. Multiple binary stars provide the means to determine helium abundances in these old stellar systems, and in turn, to improve age estimates.
Aims: Earlier measurements of the masses and radii o…
The Herschel view of massive star formation in G035.39-00.33: dense and cold filament of W48 undergoing a mini-starburst
Martin, P. G.; Hill, T.; White, G. J. +29 more
The filament IRDC G035.39-00.33 in the W48 molecular complex is one of the darkest infrared clouds observed by Spitzer. It has been observed by the PACS (70 and 160 µm) and SPIRE (250, 350, and 500 µm) cameras of the Herschel Space Observatory as part of the W48 molecular cloud complex in the framework of the HOBYS key programme. The o…
The Host Galaxies of Low-mass Black Holes
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E. +2 more
Using Hubble Space Telescope observations of 147 host galaxies of low-mass black holes (BHs), we systematically study the structures and scaling relations of these active galaxies. Our sample is selected to have central BHs with virial masses of ~105-106 M ⊙. The host galaxies have total I-band magnitudes of -23.2 …