Reverberation mapping (or Echo mapping) is an astrophysical technique for measuring the structure of the broad-line region (BLR) around a supermassive black hole at the center of an active galaxy, and thus estimating the hole's mass. It is considered a "primary" mass estimation technique, i.e., the mass is measured directly from the motion that its gravitational force induces in the nearby gas. Newton's law of gravity defines a direct relation between the mass of a central object and the speed of a smaller object in orbit around the central mass. Thus, for matter orbiting a black hole, the black-hole mass is related by the formula to the RMS velocity ΔV of gas moving near the black hole in the broad emission-line region, measured from the Doppler broadening of the gaseous emission lines. In this formula, RBLR is the radius of the broad-line region; G is the constant of gravitation; and f is a poorly known "form factor" that depends on the shape of the BLR. While ΔV can be measured directly using spectroscopy, the necessary determination of RBLR is much less straightforward. This is where reverberation mapping comes into play. It utilizes the fact that the emission-line fluxes vary strongly in response to changes in the continuum, i.e., the light from the accretion disk near the black hole. Put simply, if the brightness of the accretion disk varies, the emission lines, which are excited in response to the accretion disk's light, will "reverberate", that is, vary in response. But it will take some time for light from the accretion disk to reach the broad-line region. Thus, the emission-line response is delayed with respect to changes in the continuum. Assuming that this delay is solely due to light travel times, the distance traveled by the light, corresponding to the radius of the broad emission-line region, can be measured. Only a small handful (less than 40) of active galactic nuclei have been accurately "mapped" in this way. An alternative approach is to use an empirical correlation between RBLR and the continuum luminosity. Another uncertainty is the value of f. In principle, the response of the BLR to variations in the continuum could be used to map out the three-dimensional structure of the BLR. In practice, the amount and quality of data required to carry out such a deconvolution is prohibitive. Until about 2004, f was estimated ab initio based on simple models for the structure of the BLR. More recently, the value of f has been determined so as to bring the M–sigma relation for active galaxies into the best possible agreement with the M–sigma relation for quiescent galaxies. When f is determined in this way, reverberation mapping becomes a "secondary", rather than "primary", mass estimation technique. (Wikipedia).
How to Create a SURFACE OF REV by SPINNING ANY CURVE about ANY LINE in GeoGebra 3D
Here, we use GeoGebra's CURVE command to parameterize a segment (here, CD) in 3-space. Doing so will allow us to create a surface of revolution ABOUT ANY LINE with segment CD serving as its cross section. GeoGebra resource: https://www.geogebra.org/m/measmzyn
From playlist GeoGebra: It's REALLY THAT EASY!!! (Short Silent Screencasts)
The Masses of Quasars - B. Peterson
Fifty Years of Quasars: A Symposium in Honor of Maarten Schmidt Caltech, Pasadena, CA, USA - Sept. 9-10, 2013 More info: http://www.astro.caltech.edu/q50 Links to talks with video of speaker: http://www.astro.caltech.edu/q50/Program.html Fifty years ago, the discovery of quasars transform
From playlist Fifty Years of Quasars - September, 9-10, 2013
21. Sound localization 2: Superior olivary complex and IC
MIT 9.04 Sensory Systems, Fall 2013 View the complete course: http://ocw.mit.edu/9-04F13 Instructor: Chris Brown This video continues to discuss sound localization, including neural processing in the lateral superior olive and inferior colliculus. It also covers the auditory pathways in B
From playlist MIT 9.04 Sensory Systems, Fall 2013
Finding the Inverse of a Logarithmic Function
How to find the inverse of a logarithmic function! Broken down step by step. I promise it's really not as bad as it looks! Hope this helps! Facebook: https://www.facebook.com/braingainzofficial Instagram: https://www.instagram.com/braingainzofficial Thanks for watching! Comment below
From playlist Precalculus
Quantization and Coding in A/D Conversion
http://AllSignalProcessing.com for more great signal-processing content: ad-free videos, concept/screenshot files, quizzes, MATLAB and data files. Real sampling systems use a limited number of bits to represent the samples of the signal, resulting in quantization of the signal amplitude t
From playlist Sampling and Reconstruction of Signals
Spinning a Piecewise Function to Create a Surface of REV in GeoGebra 3D with Augmented Reality
#GeoGebra resource: www.geogebra.org/m/ybgyswtm. #MTBoS #ITeachMath
From playlist GeoGebra 3D with AR (iOS): Explorations, Demos, and Lesson Ideas
Ex 1: Find the Inverse of a Function
This video provides two examples of how to determine the inverse function of a one-to-one function. A graph is used to verify the inverse function was found correctly. Library: http://mathispower4u.com Search: http://mathispower4u.wordpress.com
From playlist Determining Inverse Functions
Year 9 Science Unit 2 Our Amazing Earth Tectonic Plates
From playlist Y9 Sci Unit 2 Earth
Secrets of the Cosmic Microwave Background
You can learn more about CuriosityStream at https://curiositystream.com/spacetime PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACE Check out the new Space Time Merch Store! https://pbsspacetime.com/ Support Space Time on P
From playlist The Cosmic Microwave Background Explained!
Using the inverse of an exponential equation to find the logarithm
👉 Learn how to convert an exponential equation to a logarithmic equation. This is very important to learn because it not only helps us explain the definition of a logarithm but how it is related to the exponential function. Knowing how to convert between the different forms will help us i
From playlist Logarithmic and Exponential Form | Learn About
quick review of how to resize an image in Geogebra
From playlist Geogebra
Lecture 7.1: Josh McDermott - Introduction to Audition, Part 1
MIT RES.9-003 Brains, Minds and Machines Summer Course, Summer 2015 View the complete course: https://ocw.mit.edu/RES-9-003SU15 Instructor: Josh McDermott The study of sound textures and high level goals of auditory processing. Anatomy and structure of the auditory system, frequency tunin
From playlist MIT RES.9-003 Brains, Minds and Machines Summer Course, Summer 2015
Frequency Domain Interpretation of Sampling
http://AllSignalProcessing.com for more great signal-processing content: ad-free videos, concept/screenshot files, quizzes, MATLAB and data files. Analysis of the effect of sampling a continuous-time signal in the frequency domain through use of the Fourier transform.
From playlist Sampling and Reconstruction of Signals
Rocking Out With Convolutions | Two Minute Papers #73
A lot of university students tend to have a lot of problems understanding convolutions. Today, we're going to talk about both many cool useful applications of convolutions and there will be a bit of intuition on how the computation is done. Among other cool applications, it turns out we ca
From playlist Two Minute Papers
How architecture helped music evolve - David Byrne
View full lesson: http://ed.ted.com/lessons/how-architecture-helped-music-evolve-david-byrne As his career grew, David Byrne went from playing CBGB to Carnegie Hall. He asks: Does the venue make the music? From outdoor drumming to Wagnerian operas to arena rock, he explores how context ha
From playlist Behind the Curtain
MIT 9.13 The Human Brain, Spring 2019 Instructor: Nancy Kanwisher View the complete course: https://ocw.mit.edu/9-13S19 YouTube Playlist: https://www.youtube.com/playlist?list=PLUl4u3cNGP60IKRN_pFptIBxeiMc0MCJP Humans use hearing in species-specific ways, for speech and music. Ongoing res
From playlist MIT 9.13 The Human Brain, Spring 2019
Creating A Cathedral Of Light Inside A Gas Tank | URBANSCREEN's 320° Light
Experience 320°Licht by URBANSCREEN, part of the exhibition "The Appearance of Beauty" at Gasometer Oberhausen. The large-scale projection installation features 21 powerful projectors streaming mind-bending graphic patterns on over 20,000 square meters of space in Oberhausen, Germany's mas
From playlist Projection Mapping inspirations
Transformational Geometry in GeoGebra: Creating Footprints
Screencast illustrates how you can use GeoGebra to transform multiple objects simultaneously. Screencast takes place in GeoGebra's Geometry App: www.geogebra.org/geometry
From playlist Geometry: Dynamic Interactives!
The wondrous life—and death—of Puerto Rico’s Arecibo Observatory
If a telescope’s 900-ton platform falls in a forest, it most definitely makes a sound. On 1 December 2020, a monumental collapse at Puerto Rico’s Arecibo Observatory unleashed a monstrous roar across the tree-covered karst landscape. In the rubble lay key components of a telescope that had
From playlist News Features