Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://hea-www.harvard.edu/AstroStat/Stat310_fMMIV/siemiginowska_21sep2004.pdf Äàòà èçìåíåíèÿ: Tue Jul 26 00:20:46 2005 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 06:20:19 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: asteroid

Astronomy in the Age of Space: Overview
A n e t a Si em i g i n o w s k a Ch a n d r a X- r a y Ce n t e r Fo r A s t r o s t a t i s t i c Wo r k i n g Gr o u p


OUTLINE
· What is astronomy?
· different type of astronomical sources

· Astronomers Tools
· how do we get basic information about the astrophysical source? · radio, IR, optical, X-ray and gamma-ray

· High Energy Sky · Chandra X-ray Observatory
· · · · examples of typical X-ray data, an example of a data analysis process statistical challenges what do we learn from the data?


What is Astronomy?
· Astronomy => "Law of the stars"
"Scientific studies of the Universe beyond the Earth involving observation, calculation and interpretation of the positions, dimensions, distribution, composition and evolution of celestial bodies and phemonena."
We b s t e r ' s N e w Co l l eg e D i ct i o n ar y


What type of celestial bodies and phenomena do we study and how?


Solar System:


Sun and sollar wind, planets, moons, asteroids, comets center, stars, binary systems, nebulae, supernovae galaxies, active galaxies and quasars, clusters of galaxies, large scale structures intergalactic medium, background radiation



Our Galaxy ­ Milky Way:




Extragalactic Objects:




the Universe:



Sat u r n

Solar System
Learn about our neighborhood!

Ju p i t er

· Images of Planets from the Hubble Space Telescope · Characteristics of planets, colors, composition,structure, environment, dynamics Mar s Ur an u s


The SUN - the nearest star!
Mau n a Lo a Ob ser vat o r y ­ o p t i cal p h o t o m et r y Vi si b l e Li g h t

Very active object when observed in different wavelenghts!
X- r ays

Yo h k h o SXT


SUN is very active!

Co r o n al Mass Ej ect i o n s

Ro t at i n g Su n sh o w s act i ve r eg i o n s

Im ag es f r o m SOHO (So l ar & Hel i o sp h er i c Ob ser vat o r y)


The Galaxy Milky Way

Spiral Galaxy - similar to Milky Way Stars and Star Clusters

Nebulae

Cat's Eye Nebula M80- the densest star cluster in Milky Way


Extragalactic Objects
Op t i cal Im ag es f r o m Hu b b l e Sp ace Tel esco p e

Act i ve Gal ax i es an d Qu asar s Cl u st er o f Gal ax i es

In t er act i n g g al ax i es


Universe
WMAP i m ag e o f t em p er at u r e f l u ct u at i o n s i n t h e Co sm i c Mi cr o w ave Back g r o u n d r ad i at i o n .

Gal ax i es i n Hu b b l e Deep Fi el d Op t i cal Im ag e


Ra i n b o w of Li g h t !

We can see t h e r ai n b o w i n Vi si b l e Li g h t , b u t el ect r o m ag n et i c w aves h ave m u ch b r o ad er r an g e.

The Earth atmosphere blocks a lot of radiation. We need satellites to observe objects in high energy.


GREAT OBSERVATORIES ON ORBIT

19912000

19922001

19891993

WMAP/ 2 0 0 1 -

20031999At acam a, Ch i l e


Op t i cal / Hu b b l e

Information from Optical and X-rays

X- r ays/ Ch an d r a

Optical/X-ray Overlayed
Credit: NASA/CXC/ESO-VLT/HST Rosati et al 2004


Perseus A
X-ray/Radio Optical

Fab i an et al (2 0 0 0 )


Op t i cal Im ag e HST

X- r ay / Ch an d r a

PKS1127-145 Quasar at z=1.18

CHANDRA X-RAY Image Revealed a Large Scale Jet


X-ray Images
· Intensity Maps
· color represents variations in the intensity

· Raw vs. Smoothed images
· true counts per pixel · average counts/pixel

· True/False color images
· color represents energy

· Temperature maps
· Color represents temperature

· Images from different bands:
X-rays/radio/optical


Perseus A CHANDRA ACIS-S

Sm o o t h ed

Co l o r co d ed
Fab i an et al (2 0 0 0 )

Raw


Angular Resolution => Sharp Image

Ei n st ei n
XMM

Chandra

FWHM ~ 0.5 arcsec

FWHM ~ 6 arcsec


First X-ray Imaging Telescope The Einstein Observatory (HEAO-2)
Nov. 1978-April 1981 High Resolution Imager

Energy: 0.15-3 keV Effective 5-20 cm2 Area
FOV ~25 arcmin
Angular resolution ~6 arcsec! Tycho Supernova Remnant (1572)

Credit: HEASARC


XMM Newton
Lau n ch ed i n Dec. 1 9 9 9 Energy Range: 0.1-15 keV Effective Area: 1500 cm2 at 1 keV FOV ~27-33arcmin Angular resolution ~6 arcsec Energy resolution: E/DE ~ 20-50

Tych o Su p er n o va Rem n an t

Aschenbach et al (2000)


CHANDRA X-ray Observatory
· · · · · · Launched in July 1999 Energy Range:0.1-10 keV Effective Area: ACIS-I ~ 500 cm2 HRC-I ~ 225 cm2 FOV: ACIS-I 16'x16' HRC-I: 30'x30' · Energy Resolution: E/DE ~ 20-50 @1keV · Angular Resolution < 1 arcsec

T ych o Su p er n o v a Color-coded image
Cr ed i t : CXC


The Chandra X-ray Observatory

Launched 5 years ago on July 23,1999 Has revolutionized X-ray astronomy What are X-rays? Example 1: Quasars Wind Example 2: Clusters of Galaxies


Wh a t i s X- r a y As t r o n o m y ?
When we look up at the night sky we see it filled with stars Bu t , Outside the narrow range of colors our eyes are sensitive to, something quite different dominates the night sky...


Powerful sources of X-rays
X-ray map of the whole sky: 100,000 `sources' Ro sat Al l Sk y Su r vey (MPE)

A power source entirely different from the nuclear fusion that drives the Sun and stars and much more efficient

X-ray Astronomy tries to find out what could cause such extraordinary power


Compare Visible light and X-rays: "1000 times"

· X-rays have:
· Wavelengths: 1/1000 visible light
· 0.1-6 nm (1-60A) vs. 500 nm (5000A)

· Energies: 1000 x visible light
· "keV" instead of "eV" (electron volts) · About 0.02 Joules/photon

· Temperatures: 1000 times hotter
· 10 million degrees vs. 10 thousand degrees for stars · E=kT (k= Boltzman's constant, 1.398e-9 J/K)
SNR G2 9 2 . 0 + 1 . 8 (Hu g h es et al . )

Credit: Elvis 2004


What gets so hot?
· Surely not much can get so hot as a million degrees? · Oh yes it can...
Explosions: Supernovae

and their remnants
Su p er n o va 1 9 8 7 a

Particles moving near the speed of light in
magnetic fields Cr ab Neb u l a

Matter falling into
deep gravitational wells A b el l 2 0 2 9 Cl u st er o f g al ax i es

¼ su n ­ cen t au r i

su n

Cen t au r i

su n

A n d r o m ed a n ear est g al ax y


Hubble Space Telescope Optical Image Chandra X-ray Image

Pl e n t y of g a l a x i es!


Chandra's sharp focus revolutionizes our understanding
Earth observing satellite equivalents of ...

SPA CE IM AGING

Best X- r ay i m ag e o f w h o l e sk y (ROSAT) A n y s i g n o f l i f e?

Best X- r ay i m ag es b ef o r e Ch an d r a (ROSAT) Wh at 's t h i s o d d thing?

Ch an d r a i m ag es

I g et i t !
Credit: Elvis 2003


X-ray Studies with Chandra
Hi g h Re s o l u t i o n X- ra y Hi g h Re s o l u t i o n Im a g i n g Sp e c t r a


Absorption Lines in Quasars Spectra

Li n e s !

Li n e s !

Pet t i n i 2 0 0 3


What do we learn?
· The width of the lines => Velocity · Line location => Composition · Energy of the line => Temperature · Line variability => Distance from the Quasar


Quasars Wind

Hot outflowing wind, large distance from the center!


Example 2: Cluster of Galaxies

X-rays

Optical


Optical => X-ray Image of Perseus Cluster of Galaxies

Ce n t ra l Ga l a x y

NASA/ CXC Fab i an et al 2 0 0 3


Questions:
· What is the temperature of the emitting gas? · What prevents the cooling process? · Is there a cold gas? Where? · What process heats this gas? · What process creates the cavities? · Can we determine the age of the structures?

Perseus Cluster

Fab i an et al 2 0 0 3


Image Processing

NASA / CXC/ Fab i an et al 2 0 0 3


Il l u st r at i o n o f Ri p p l es i n Per seu s


Per se u s cl u st er Contours ­ Radio wavelength


An i m at i o n o f t h e Per seu s cl u st er

Co p yr i g h t : NASA / CXC/ Fab i an et al . 2 0 0 3


Scientific Analysis
· How significant are the features in the image? · How real is the image? · What is the distance between the ripples? · Is this the best model? · How to discriminate between different models?


What are the goals of Data Analysis in Astronomy?
· Create a nice picture :-) · Understand the nature of the source:
· Understand the shape and size of the emitting regions · Understand temperature distribution, velocity density distribution, composition and metallicity etc. · Differentiate between emission processes. · Understand energy and power involved in the observed emission

· Evolution of the source and how it relates to other sources.