Radiation astronomy/Temporals A temporal distribution
is a distribution over time. Also known as a time distribution. A temporal distribution usually has the independent variable 'Time' on the abscissa
and other variables viewed approximately orthogonal to it. The time distribution can move forward in time, for example, from the present into the future, or backward in time, from the present into the past. Usually, the abscissa is plotted forward in time with the earlier time at the intersection with the ordinate
variable at left. Geologic time is often plotted on the abscissa versus phenomena on the ordinate or as a twenty-four hour clock analogy.
This is a montage of ten years' worth of Yohkoh SXT images, demonstrating the variation in solar activity during a sunspot cycle, from after August 30, 1991, to September 6, 2001. Credit: David Chenette, Joseph B. Gurman, Loren W. Acton.
Hard gamma rays
Emergence of IC 310 is captured in a series of images. Credit: A. Neronov et al. and NASA/DOE/LAT collaboration.
"Fermi's Large Area Telescope (LAT) scans the entire sky every three hours, continually deepening its portrait of the sky in gamma rays, the most energetic form of light. While the energy of visible light falls between about 2 and 3 electron volts, the LAT detects gamma rays with energies ranging from 20 million to more than 300 billion electron volts (GeV)."
"At higher energies, gamma rays are rare. Above 10 GeV, even Fermi's LAT detects only one gamma ray every four months from some sources."
"Any object producing gamma rays at these energies is undergoing extraordinary astrophysical processes. More than half of the 496 sources [the Fermi hard-source list] in the new census are active galaxies, where matter falling into a supermassive black hole powers jets that spray out particles at nearly the speed of light."
"One example is the well-known radio galaxy NGC 1275 [above left], which is a bright, isolated source below 10 GeV. At higher energies it fades appreciably and another nearby source begins to appear. Above 100 GeV, NGC 1275 becomes undetectable by Fermi, while the new source, the radio galaxy IC 310, shines brightly."
"The catalog serves as an important roadmap for ground-based facilities called Atmospheric Cherenkov Telescopes, which have amassed about 130 gamma-ray sources with energies above 100 GeV. They include the Major Atmospheric Gamma Imaging Cherenkov telescope (MAGIC) on La Palma in the Canary Islands, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia."
The images show LIGO and Livingston, Louisiana, measurement of gravitational waves. Credit: B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration).
This gravitational wave spectrum includes sources and detectors. Credit: NASA Goddard Space Flight Center.
appears to be cylindrical waves of radiation produced by relativistic, undulatory gravitational fields in Euclidean space.
As the gravitational interaction is 10-36 that of the electromagnetic interaction to produce gravitational radiation requires a massive oscillator.
At right are the results from the first gravitational radiation detection. The images show the radiation signals received by the Laser Interferometer Gravitational Observatory (LIGO) instruments at Hanford, Washington (left) and Livingston, Louisiana (right) and comparisons of these signals to the signals expected due to a black hole merger event.
The wavelength of the gravitational waves is given by for example: 3 x 108 m‧s-1/400 Hz = 750,000 m, which is way longer than radio waves but expected for such a weak oscillator. 35 Hz corresponds to 8,600,000 m.
LIGO operates two detectors located 3000 km (1800 miles) apart: One in eastern Washington near Hanford, and the other near Livingston, Louisiana. The photo on the left shows the Livingston detector.
"According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide at nearly half the speed of light and form a single, more massive black hole, converting a portion of the combined black holes' mass to energy, according to Einstein's formula E=mc2
. This energy is emitted as a final strong burst of gravitational waves. These are the gravitational waves that LIGO observed."
"LIGO’s twin interferometers bounce laser beams between mirrors at the opposite ends of 4-kilometre-long vacuum pipes that are set perpendicularly to each other. A gravitational wave passing through will alter the length of one of the arms, causing the laser beams to shift slightly out of sync."
Later detection confirmed the fusion of two massive stellar-sized objects, a binary neutron star merger.
"According to Einstein's field equations, photon matter subject to quadruple oscillations is a source of gravitational waves."
"In this work, we present a solution to the first stage of a new two-stage global treatment of the vacuum binary black hole problem [1, 2]. The approach, based upon characteristic evolution, has been carried out in the regime of Schwarzschild perturbations where advanced and retarded solutions of the linearized problem can be rigorously identified . Computational experiments are necessary to study the applicability of the approach to the nonlinear regime. From a time-reversed viewpoint, this first stage is equivalent to the determination of the outgoing radiation emitted from the fission of a white hole in the absence of ingoing radiation. This provides the physically correct “retarded” waveform for a white hole fission, were such events to occur in the universe. Although there is no standard astrophysical mechanism for producing white holes from a nonsingular matter distribution, white holes of primordial or quantum gravitational origin cannot be ruled out."
"This fission problem has a simpler formulation as a characteristic initial value problem than the black hole merger problem. The boundary of the (conformally compactified) exterior spacetime contains two null hypersurfaces where boundary conditions must be satisfied: past null infinity I−, where the incoming radiation must vanish, and the white hole event horizon H−, which must describe a white hole, which is initially in equilibrium with no ingoing radiation and then distorts and ultimately fissions into two white holes with the emission of outgoing gravitational waves."
An almost identical signal could originate from a comparable much more massive neutron star fission.
"This is an exciting time to study gravitation, astrophysics and cosmology. Through challenging cosmic microwave background (CMB) and supernovae observations cosmology has been turned on its head. Gravitational radiation astronomy should be the next contributor to this revolution in astrophysics and cosmology."
This chart shows the increasing accuracy of NIST (formerly NBS) atomic clocks. Credit: National Institutes of Standards and Technology (NIST), USA.
The FOCS 1 is a continuous cold caesium fountain atomic clock in Switzerland. Credit: METAS.
A key value on the time axis for collecting physical data is the starting time
. “Incandescents reach full brightness a fraction of a second after being switched on.”
The FOCS 1 continuous cold cesium fountain atomic clock started operating in 2004 at an uncertainty of one second in 30 million years. The clock is in Switzerland.
The use of satellites should provide ten times the information as sounding rockets or balloons.
A control group for a radiation satellite would contain
- a radiation astronomy telescope,
- a two-way communication system,
- a positional locator,
- an orientation propulsion system, and
- power supplies and energy sources for all components.
A control group for radiation astronomy satellites may include an ideal or rigorously stable orbit so that the satellite observes the radiation at or to a much higher resolution than an Earth-based ground-level observatory is capable of.
- ↑ 1.0 1.1 1.2 1.3 1.4 Trent J. Perrotto (10 January 2012). NASA's Fermi Space Telescope Explores New Energy Extremes. Washington, DC USA: NASA. http://www.nasa.gov/mission_pages/GLAST/news/energy-extremes.html. Retrieved 3 November 2016.
- ↑ A. Einstein and N. Rosen (January 1937). "On gravitational waves". Journal of the Franklin Institute 223 (1): 43-54. doi:10.1016/S0016-0032(37)90583-0. http://www.sciencedirect.com/science/article/pii/S0016003237905830?via%3Dihub. Retrieved 2018-1-3.
- ↑ Ivy F. Kupec (11 February 2016). Gravitational waves detected 100 years after Einstein's prediction. Alexandria, Virginia, USA: National Science Foundation. pp. 1. https://www.nsf.gov/news/news_summ.jsp?cntn_id=137628. Retrieved 3 January 2018.
- ↑ Davide Castelvecchi & Alexandra Witze (11 February 2016). "Einstein's gravitational waves found at last LIGO 'hears' space-time ripples produced by black-hole collision". Nature. doi:10.1038/nature.2016.19361. http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361. Retrieved 2018-1-3.
- ↑ B. P. Abbott, the LIGO Scientific Collaboration & the Virgo Collaboration (16 October 2017). "GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral". Physical Review Letters 119 (16). doi:10.1103/PhysRevLett.119.161101.
- ↑ Constantin Sandu and Dan Brasoveanu (2007). Sonic Electromagnetic Gravitational Spacecraft, Part - Principles, In: AIAA SPACE 2007 Conference & Exposition. AIAA 2007-6203. American Institute of Aeronautics and Astronautics. https://arc.aiaa.org/doi/abs/10.2514/6.2007-6203. Retrieved 10 January 2018.
- ↑ 7.0 7.1 Roberto Gómez, Sascha Husa, Luis Lehner, and Jeffrey Winicour (15 September 2002). "Gravitational waves from a fissioning white hole". Physical Review D 66 (6): 1-9. doi:10.1103/PhysRevD.66.064019. https://arxiv.org/pdf/gr-qc/0205038. Retrieved 2018-1-10.
- ↑ Nelson Christensen, Renate Meyer and Adam Libson (1 December 2003). "A Metropolis–Hastings routine for estimating parameters from compact binary inspiral events with laser interferometric gravitational radiation data". Classical and Quantum Gravity 21 (1): 317-330. doi:10.1088/0264-9381/21/1/023. http://people.carleton.edu/~nchriste/CQG03.pdf. Retrieved 2018-1-19.
- ↑ Compact fluorescent lamp. San Francisco, California: Wikimedia Foundation, Inc. June 10, 2012. http://en.wikipedia.org/wiki/Compact_fluorescent_lamp#Starting_time. Retrieved 2012-06-16.
- ↑ Dennis McCarthy, P. Kenneth Seidelmann (2009). TIME from Earth Rotation to Atomic Physics. Weinheim: Wiley-VCH.
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Last edited on 31 May 2021, at 18:32
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