Search Publications
Testing the Unification Model for Active Galactic Nuclei in the Infrared: Are the Obscuring Tori of Type 1 and 2 Seyferts Different?
Pérez García, A. M.; Díaz-Santos, T.; Packham, C. +7 more
We present new mid-infrared imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample studied in a previous work to compare the properties of Type-1 and Type-2 Seyfert tori using clumpy torus models and a Bayesian approach to fit the infrared (IR) …
Planck early results. XX. New light on anomalous microwave emission from spinning dust grains
Kneissl, R.; Miville-Deschênes, M. -A.; Boulanger, F. +213 more
Anomalous microwave emission (AME) has been observed by numerous experiments in the frequency range ~10-60 GHz. Using Planck maps and multi-frequency ancillary data, we have constructed spectra for two known AME regions: the Perseus and ρ Ophiuchi molecular clouds. The spectra are well fitted by a combination of free-free radiation, cosmic microwa…
The Spin of the Supermassive Black Hole in NGC 3783
Nandra, K.; Iwasawa, K.; Fabian, A. C. +9 more
The Suzaku AGN Spin Survey is designed to determine the supermassive black hole spin in six nearby active galactic nuclei (AGNs) via deep Suzaku stares, thereby giving us our first glimpse of the local black hole spin distribution. Here, we present an analysis of the first target to be studied under the auspices of this Key Project, the Seyfert ga…
The Relationships among Compact Stellar Systems: A Fresh View of Ultracompact Dwarfs
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +1 more
We use a combined imaging and spectroscopic survey of the nearby central cluster galaxy, M87, to assemble a sample of 34 confirmed ultracompact dwarfs (UCDs) with half-light radii of gsim10 pc measured from Hubble Space Telescope images. This doubles the existing sample in M87, making it the largest such sample for any galaxy, while extending the …
Pan-STARRS1 Discovery of Two Ultraluminous Supernovae at z ≈ 0.9
Price, P. A.; Berger, E.; Kirshner, R. P. +29 more
We present the discovery of two ultraluminous supernovae (SNe) at z ≈ 0.9 with the Pan-STARRS1 Medium Deep Survey. These SNe, PS1-10ky and PS1-10awh, are among the most luminous SNe ever discovered, comparable to the unusual transients SN 2005ap and SCP 06F6. Like SN 2005ap and SCP 06F6, they show characteristic high luminosities (M bol…
Astrometry and Photometry with HST WFC3. II. Improved Geometric-Distortion Corrections for 10 Filters of the UVIS Channel
Anderson, J.; Bedin, L. R.; Bellini, A.
We present an improved geometric-distortion solution for the Hubble Space Telescope UVIS channel of Wide Field Camera 3 for 10 broadband filters. The solution is made up of three parts: (1) a third-order polynomial to deal with the general optical distortion, (2) a table of residuals that accounts for both chip-related anomalies and fine-structure…
The Impact of Galaxy Interactions on Active Galactic Nucleus Activity in zCOSMOS
Finoguenov, A.; Jahnke, K.; Silverman, J. D. +52 more
Close encounters between galaxies are expected to be a viable mechanism, as predicted by numerical simulations, by which accretion onto supermassive black holes can be initiated. To test this scenario, we construct a sample of 562 galaxies (M * > 2.5 × 1010 M ⊙) in kinematic pairs over the redshift range 0.25 &l…
Quasar Accretion Disks are Strongly Inhomogeneous
Agol, Eric; Dexter, Jason
Active galactic nuclei have been observed to vary stochastically with 10%-20% rms amplitudes over a range of optical wavelengths where the emission arises in an accretion disk. Since the accretion disk is unlikely to vary coherently, local fluctuations may be significantly larger than the global rms variability. We investigate toy models of quasar…
Search for brown-dwarf companions of stars
Zucker, S.; Queloz, D.; Sahlmann, J. +7 more
Context. The frequency of brown-dwarf companions in close orbit around Sun-like stars is low compared to the frequency of planetary and stellar companions. There is presently no comprehensive explanation of this lack of brown-dwarf companions.
Aims: By combining the orbital solutions obtained from stellar radial-velocity curves and Hipparcos …
Gas Clumping in the Outskirts of ΛCDM Clusters
Nagai, Daisuke; Lau, Erwin T.
Recent Suzaku X-ray observations revealed that the observed entropy profile of the intracluster medium (ICM) deviates significantly from the prediction of hydrodynamical simulations of galaxy clusters. In this work, we show that gas clumping introduces significant biases in X-ray measurements of the ICM profiles in the outskirts of galaxy clusters…