16 research outputs found
Correlated radio--X-ray variability of Galactic Black Holes: A radio--X-ray flare in Cygnus X-1
We report on the first detection of a quasi-simultaneous radio-X-ray flare of
Cygnus X-1. The detection was made on 2005 April 16 with pointed observations
by the Rossi X-ray Timing Explorer and the Ryle telescope, during a phase where
the black hole candidate was close to a transition from the its soft into its
hard state. The radio flare lagged the X-rays by approximately 7 minutes,
peaking at 3:20 hours barycentric time (TDB 2453476.63864). We discuss this lag
in the context of models explaining such flaring events as the ejection of
electron bubbles emitting synchrotron radiation.Comment: 4 pages, 4 figure
The LOFT Ground Segment
LOFT, the Large Observatory For X-ray Timing, was one of the ESA M3 mission
candidates that completed their assessment phase at the end of 2013. LOFT is
equipped with two instruments, the Large Area Detector (LAD) and the Wide Field
Monitor (WFM). The LAD performs pointed observations of several targets per
orbit (~90 minutes), providing roughly ~80 GB of proprietary data per day (the
proprietary period will be 12 months). The WFM continuously monitors about 1/3
of the sky at a time and provides data for about ~100 sources a day, resulting
in a total of ~20 GB of additional telemetry. The LOFT Burst alert System
additionally identifies on-board bright impulsive events (e.g., Gamma-ray
Bursts, GRBs) and broadcasts the corresponding position and trigger time to the
ground using a dedicated system of ~15 VHF receivers. All WFM data are planned
to be made public immediately. In this contribution we summarize the planned
organization of the LOFT ground segment (GS), as established in the mission
Yellow Book 1 . We describe the expected GS contributions from ESA and the LOFT
consortium. A review is provided of the planned LOFT data products and the
details of the data flow, archiving and distribution. Despite LOFT was not
selected for launch within the M3 call, its long assessment phase (> 2 years)
led to a very solid mission design and an efficient planning of its ground
operations.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014:
Ultraviolet to Gamma Ray, 91446
The Large Observatory for x-ray timing
The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final down-selection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supra-nuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a WideField Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study
The LOFT mission concept: a status update
The Large Observatory For x-ray Timing (LOFT) is a mission concept which was proposed to ESA as M3 and M4 candidate in the framework of the Cosmic Vision 2015-2025 program. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument and the uniquely large field of view of its wide field monitor, LOFT will be able to study the behaviour of matter in extreme conditions such as the strong gravitational field in the innermost regions close to black holes and neutron stars and the supra-nuclear densities in the interiors of neutron stars. The science payload is based on a Large Area Detector (LAD, >8m2 effective area, 2-30 keV, 240 eV spectral resolution, 1 degree collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g., GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the current technical and programmatic status of the mission