Deep Extragalactic Space - PowerPoint PPT Presentation

Loading...

PPT – Deep Extragalactic Space PowerPoint presentation | free to download - id: 78df14-NDE3N



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Deep Extragalactic Space

Description:

Deep Extragalactic Space The basic yardstick of distance is now the Megaparsec = 3.3 million light years Question: how do we determine the distances to such ... – PowerPoint PPT presentation

Number of Views:25
Avg rating:3.0/5.0
Slides: 23
Provided by: Steven1012
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Deep Extragalactic Space


1
Deep Extragalactic Space
  • The basic yardstick of distance is now the
    Megaparsec 3.3 million light years
  • Question how do we determine the distances to
    such remote objects?

2
Examples of extremely distant clusters of galaxies
  • You cant see Cepheids that far out

3
The Hubble Relation for Galaxies
  • Galaxies in all directions receding from us
  • The more distant they are, the faster they are
    receding
  • vH0d
  • v speed of recession (km/sec), d distance
    (Mpc), H0 Hubble Constant, (km/sec/Mpc), H0
    70 km/sec/Mpc

4
The Hubble Relation for Galaxies
  • If you measure the redshift, you know the distance

5
With measurements of distances, you can map out
the distribution of galaxies
6
What is the meaning of Hubbles Law?
  • Are we at the center of the universe and
    everything is moving away from us?
  • True analogy observer on an expanding jungle gym
  • The universe is expanding
  • Hubble Law was the beginning of the science of
    cosmology

7
First, lets examine some of the variety in the
hundreds of thousands of galaxies that have been
examined
8
An interludeRadio Astronomywill make sense later
  • To remind you of what you already know.
  • Radio astronomy study of universe with EM waves
    having wavelength from about 1 millimeter to 50
    meters
  • Comparison optical astronomy studies wavelengths
    between 4E-07 to 7E-07 meters

9
The Radio Sky
Radio sources many associated with giant
elliptical galaxies
10
A region 2 degrees square at RA23h, Dec20d.
The sky at 21cm wavelength
11
Radio Galaxies, e.g. 3C296
Radio galaxies shine by a mechanism called
synchrotron radiation
12
What is synchrotron radiation?
Accelerated electrons radiate EM waves DEMO
13
History of Radio Astronomy, circa 1960
  • Some of the brightest radio sources, 3C48, 3C273,
    did not seem to be associated with galaxies, but
    with star-like objects

14
Spectra of these sources showed highly redshifted
lines great distances
Z (w-w0)/w0 0.16, 0.48, 1.7, 4.42 !! Quasar
Quasi-Stellar Radio Sources
15
With Hubble Space Telescope, we have imaged
Quasars
16
What are quasars?
Physically what They are
Artistic view of an early quasar
17
In quasars and radio galaxies, there is a
connection from the small to the extremely large
M87
18
M87 at radio wavelengths it exists on many scales
19
The Central Engines of quasars and radio
galaxies black holes of 1 - 10 billion solar
masses
20
Summary of Quasar Characteristics
  • Clearly are a brilliant, energetic phenomenon in
    centers of galaxies
  • Quasars are very distant. We see them as they
    were long ago
  • Lets look at the distribution of quasar
    redshifts

21
Question what does this mean?
7236 quasars
22
Extragalactic Astronomy as a Time Machine
About PowerShow.com