0000000000403429

AUTHOR

D. Psaltis

showing 3 related works from this author

The Large Observatory for X-ray Timing (LOFT)

2012

High-time-resolution X-ray observations of compact objects provide direct access to strong-field gravity, to the equation of state of ultra-dense matter and to black hole masses and spins. A 10 m^2-class instrument in combination with good spectral resolution is required to exploit the relevant diagnostics and answer two of the fundamental questions of the European Space Agency (ESA) Cosmic Vision Theme "Matter under extreme conditions", namely: does matter orbiting close to the event horizon follow the predictions of general relativity? What is the equation of state of matter in neutron stars? The Large Observatory For X-ray Timing (LOFT), selected by ESA as one of the four Cosmic Vision M…

Event horizonX-ray timingMission7. Clean energy01 natural sciencesneutron starsT175 Industrial research. Research and developmentBINARIESSettore FIS/05 - Astronomia E AstrofisicaALICESILICON DRIFT DETECTORObservatoryEQUATIONneutron star010303 astronomy & astrophysicsHigh Energy Astrophysical Phenomena (astro-ph.HE)Physics[SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE]Astrophysics::Instrumentation and Methods for AstrophysicsMissions X-ray timing compact objects black holes neutron starscompact objectsAstrophysics - Instrumentation and Methods for AstrophysicsAstrophysics - High Energy Astrophysical PhenomenaPROPORTIONAL COUNTER[PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE]Active galactic nucleusCosmic VisionX-ray astronomy; high time variabilityAstrophysics::High Energy Astrophysical Phenomenablack holes; compact objects; Missions; neutron stars; X-ray timing;FOS: Physical sciencesMissionsX-ray astronomy0103 physical sciencesOSCILLATIONSInstrumentation and Methods for Astrophysics (astro-ph.IM)Supermassive black holehigh time variability010308 nuclear & particles physicsAstronomyCONSTRAINTSAstronomy and Astrophysicsblack holesGalaxyBlack holeNeutron starSpace and Planetary ScienceQB460-466 AstrophysicsDISCOVERYBLACK-HOLESUPERAGILE
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Sgr A* 1.3mm VLBI observations with the EHT in 2013

2019

We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A*, at 1.3mm (230GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional uv coverage in the N-S direction, and leads to a spatial resolution of ~30 {mu}as (~3 Schwarzschild radii) for Sgr A*. The source is detected even at the longest baselines with visibility amplitudes of ~4%-13% of the total flux density. We argue that such flux densities …

Galactic centerobservational astronomygalactic and extragalactic astronomyAstrophysics and AstronomyInterferometryAstrophysics::High Energy Astrophysical PhenomenaPhysicsNatural SciencesMillimeter astronomyAstrophysics::Galaxy AstrophysicsSubmillimeter astronomy
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3C 279 Event Horizon Telescope imaging

2020

3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable gamma-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope (EHT) at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array (ALMA), at an angular resolution of ~20uarcsec (at a redshif…

observational astronomygalactic and extragalactic astronomyAstrophysics and AstronomyInterferometryAstrophysics::High Energy Astrophysical PhenomenaRadio galaxiesPhysicsGalaxiesNatural Sciences
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