Search Publications
Supermassive Black Holes, Pseudobulges, and the Narrow-line Seyfert 1 Galaxies
Peterson, Bradley M.; Mathur, Smita; Grupe, Dirk +1 more
We present Hubble Space Telescope Advanced Camera for Surveys (ACS) observations of 10 galaxies that host narrow-line Seyfert 1 (NLS1) nuclei, believed to contain relatively smaller mass black holes accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear point source (AGN), a bulge, and a disk, and fitted the bulge with a S…
Mid- and Far-infrared Properties of a Complete Sample of Local Active Galactic Nuclei
Nakagawa, Takao; Oyabu, Shinki; Gandhi, Poshak +4 more
We investigate the mid- (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert Telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the AKARI infrared survey catalogs complemented by those with Infrared Astronomical Satellite…
Herschel images of Fomalhaut. An extrasolar Kuiper belt at the height of its dynamical activity
Ivison, R. J.; Fridlund, M.; Blommaert, J. A. D. L. +33 more
Context. Fomalhaut is a young (2 ± 1 × 108 years), nearby (7.7 pc), 2 M⊙ star that is suspected to harbor an infant planetary system, interspersed with one or more belts of dusty debris.
Aims: We present far-infrared images obtained with the Herschel Space Observatory with an angular resolution between 5.7'' and 36.7'' a…
Hα Equivalent Widths from the 3D-HST Survey: Evolution with Redshift and Dependence on Stellar Mass
Schmidt, Kasper B.; Franx, Marijn; van Dokkum, Pieter +12 more
We investigate the evolution of the Hα equivalent width, EW(Hα), with redshift and its dependence on stellar mass, using the first data from the 3D-HST survey, a large spectroscopic Treasury program with the Hubble Space Telescope Wide Field Camera 3. Combining our Hα measurements of 854 galaxies at 0.8 < z < 1.5 with those of ground-based s…
A Far-ultraviolet Atlas of Low-resolution Hubble Space Telescope Spectra of T Tauri Stars
Herczeg, Gregory J.; Valenti, Jeff A.; Brown, Alexander +6 more
We present a far-ultraviolet (FUV) spectral atlas consisting of spectra of 91 pre-main-sequence stars. Most stars in this sample were observed with the Space Telescope Imaging Spectrograph and Advanced Camera for Surveys on the Hubble Space Telescope (HST). A few archival spectra from the International Ultraviolet Explorer and the Goddard High Res…
Gas-rich mergers and feedback are ubiquitous amongst starbursting radio galaxies, as revealed by the VLA, IRAM PdBI and Herschel
Ivison, R. J.; Smail, Ian; Ibar, E. +14 more
We report new, sensitive observations of two z ∼ 3-3.5 far-infrared-luminous radio galaxies, 6C 1909+72 and B3 J2330+3927, in the 12CO J = 1-0 transition with the Karl Jansky Very Large Array and at 100-500 m using Herschel, alongside new and archival 12CO J = 4-3 observations from the Plateau de Bure Interferometer. We intro…
Can Dust Emission be Used to Estimate the Mass of the Interstellar Medium in Galaxies—A Pilot Project with the Herschel Reference Survey
Gear, Walter; Wilson, Christine D.; De Looze, Ilse +23 more
The standard method for estimating the mass of the interstellar medium (ISM) in a galaxy is to use the 21 cm line to trace the atomic gas and the CO 1-0 line to trace the molecular gas. In this paper, we investigate the alternative technique of using the continuum dust emission to estimate the mass of gas in all phases of the ISM. Using Herschel o…
The Role of Streamers in the Deflection of Coronal Mass Ejections: Comparison between STEREO Three-dimensional Reconstructions and Numerical Simulations
Mierla, M.; Poedts, S.; Bemporad, A. +3 more
On 2009 September 21, a filament eruption and the associated coronal mass ejection (CME) were observed by the Solar Terrestrial Relations Observatory (STEREO) spacecraft. The CME originated from the southern hemisphere and showed a deflection of about 15° toward the heliospheric current sheet (HCS) during the propagation in the COR1 field of view.…
Spatially coupled inversion of spectro-polarimetric image data. I. Method and first results
van Noort, M.
Context. When inverting solar spectra, image degradation effects that are present in the data are usually approximated or not considered.
Aims: We develop a data reduction method that takes these issues into account and minimizes the resulting errors.
Methods: By accounting for the diffraction PSF of the telescope during the inversions, …
Separation of Two Contributions to the High Energy Emission of Cygnus X-1: Polarization Measurements with INTEGRAL SPI
Clark, D. J.; Jourdain, E.; Roques, J. P. +1 more
Operational since 2002 on board the INTEGRAL observatory, the SPI spectrometer can be used to perform polarization measurements in the hard X-ray/softγ-ray domain (~130 keV-8 MeV). However, this phenomenon is complex to measure at high energy and requires high fluxes. Cyg X-1 appears to be the best candidate amongst the X-ray binaries since it is …