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We present results of an optical (I band) monitoring of a sample of 22 Seyfert I galaxies. We aimed to detect microvariability with time resolution from ~ 6 minutes down to 30 seconds for the most luminous one. It is the largest survey ever…

Astrophysics · Physics 2007-05-23 P. O. Petrucci , A. Chelli , G. Henri , I. Cruz-Gonzales , L. Salas , R. Mujica

Weak lensing by large-scale structure allows a direct measure of the dark matter distribution. We have used parallel images taken with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to measure weak lensing, or…

The large optical reflector (~ 100 m^2) of a H.E.S.S. Cherenkov telescope was used to search for very fast optical transients of astrophysical origin. 43 hours of observations targeting stellar-mass black holes and neutron stars were…

Astrophysics · Physics 2009-11-13 C. Deil , W. Domainko , G. Hermann , A. -C. Clapson , A. Förster , C. van Eldik , W. Hofmann

The DECam Plane Survey is a five-band optical and near-infrared survey of the southern Galactic plane with the Dark Energy Camera at Cerro Tololo. The survey is designed to reach past the main-sequence turn-off at the distance of the…

Astrophysics of Galaxies · Physics 2018-02-21 E. F. Schlafly , G. M. Green , D. Lang , T. Daylan , D. P. Finkbeiner , A. Lee , A. M. Meisner , D. Schlegel , F. Valdes

The gravitational lens configuration where a background galaxy is closely aligned with a foreground galaxy, can provide accurate measurement of the dark matter density profile in the foreground galaxy, free of dynamical assumptions.…

Astrophysics · Physics 2009-11-11 J. P. Willis , P. C. Hewett , S. J. Warren

We propose using large Air Cerenkov Telescopes (ACT's) to search for optical, pulsed signals from extra-terrestrial intelligence. Such dishes collect tens of photons from a nanosecond-scale pulse of isotropic equivalent power of tens of…

Astrophysics · Physics 2007-05-23 David Eichler , Gregory Beskin

The lack of detected pulsars at the Galactic Center (GC) region is a long-standing mystery. We argue that the high stellar density in the central parsec around the GC is likely to result in a pulsar population dominated by millisecond…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Jean-Pierre Macquart , Nissim Kanekar

We present new results of our program to systematically search for strongly lensed galaxies in the Sloan Digital Sky Survey (SDSS) imaging data. In this study six strong lens systems are presented which we have confirmed with follow-up…

The pioneering experiments of linear spectroscopy were performed using flames in the 1800s, but nonlinear optical measurements had to wait until lasers became available in the twentieth century. Because the nonlinear cross section of…

Quantum Physics · Physics 2016-07-13 Andreas Maser , Benjamin Gmeiner , Tobias Utikal , Stephan Götzinger , Vahid Sandoghdar

Context: The nearby pair of solar-type stars Alpha Centauri is a favorable target for an imaging search for extrasolar planets. Indications exist that the gravitational mass of Alpha Cen B could be higher than its modeled mass, the…

Astrophysics · Physics 2016-08-15 Pierre Kervella , Frédéric Thévenin

We report on the progress of our search for serendipitous distant X-ray galaxy clusters in the ROSAT PSPC pointed observations archive. The initial aim of our work is to measure the X-ray luminosity function of clusters down to 4 x 10^-14…

Astrophysics · Physics 2007-05-23 D. J. Burke , C. A. Collins , R. C. Nichol , A. K. Romer , B. Holden , R. M. Sharples , M. P. Ulmer

We report on a time-domain search for pulsars in 44 steep spectrum radio sources originally identified from recent imaging surveys. The time-domain search was conducted at 327 MHz using the Ooty radio telescope, and utilized a semi-coherent…

High Energy Astrophysical Phenomena · Physics 2018-09-05 Yogesh Maan , Cees Bassa , Joeri van Leeuwen , M. A. Krishnakumar , Bhal Chandra Joshi

Atmospheric Cerenkov Telescopes, including HESS and MAGIC, have detected a spectrum of gamma-rays from the galactic center region which extends from $\sim$200 GeV or lower, to at least $\sim$10 TeV. Although the source of this radiation is…

Astrophysics · Physics 2008-11-26 Gabrijela Zaharijas , Dan Hooper

We present overall specifications and science goals for a new optical and near-infrared (350 - 1650 nm) instrument designed to greatly enlarge the current Search for Extraterrestrial Intelligence (SETI) phase space. The Pulsed All-sky…

We present the results of an unbiased radio search for gravitational lensing events with image separations between 15 and 60 arcsec, which would be associated with clusters of galaxies with masses >10^{13-14}M_{\sun}. A parent population of…

Astrophysics · Physics 2009-10-31 P. M. Phillips , I. W. A. Browne , P. N. Wilkinson

We present a sample of 80 candidate strongly lensed galaxies with flux density above 100mJy at 500{\mu}m extracted from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), over an area of 600 square degrees. Available imaging…

We report the discovery of a bright ($f(250\mum) > 400$ mJy), multiply-lensed submillimeter galaxy \obj\ in {\it Herschel}/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880\mum\ Submillimeter Array…

The existence of strong lensing systems with Einstein radii (Re) covering the full mass spectrum, from ~1-2" (produced by galaxy scale dark matter haloes) to >10" (produced by galaxy cluster scale haloes) have long been predicted. Many…

Galaxy clustering is a sensitive probe of the expansion history and growth of structure of the universe, and key degeneracies can be broken by combining these data with measurements of cosmic shear and galaxy-galaxy lensing (a so-called…

Due to fundamental limitations of accelerators, only cosmic rays can give access to centre-of- mass energies more than one order of magnitude above those reached at the LHC. In fact, extreme energy cosmic rays (1018 eV - 1020 eV) are the…

Instrumentation and Methods for Astrophysics · Physics 2014-11-21 Carlo Stella , Michele Palatiello , Pedro Assis , Pedro Brogueira , Catarina Espirito Santo , Patricia Goncalves , Mario Pimenta , Alessandro De Angelis