March 18, 2003Lynn Cominsky - Cosmology A3501 Professor Lynn Cominsky Department of Physics and...

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March 18, 2003 Lynn Cominsky - Cosmology A350

Professor Lynn Cominsky

Department of Physics and Astronomy

Offices: Darwin 329A and NASA EPO

(707) 664-2655

Best way to reach me: lynnc@charmian.sonoma.edu

Astronomy 350Cosmology

Group 7

Keith BuckleyEmily HaneyBrooke KrystosekAlex McMahon

Shapes of Galaxies Spirals

disk shaped with spiral arms often have bright bulges in center contain interstellar gas, nebulae, star forming

regions, open clusters and globular clusters Barred Spirals

spiral arms emerge from end of bar gas from outer part of galaxy funneled to center

through the bar, forming new stars in bulge Lenticular (“lens-shaped”)

flattened disks of gas and dust no spiral arms

Shapes of Galaxies Ellipticals

range from spherical to foot-ball shapes lots of old stars and globular clusters star formation is over or just restarting maybe the result of collision and merger of smaller

galaxies Irregulars

lots of gas and new stars forming rather small compared to spirals and ellipticals

Low surface Brightness lots of gas, but few stars can be rather large

Galaxy Formation movie

Formation of galaxies in cold dark matter universe

M31/Andromeda

Our nearest spiral neighbor

2 million light years away

Center of M31 has two optical nuclei

M31/Chandra X-ray

Image of central part of our neighbor M31

Bright X-ray sources are binaries with black holes or neutron stars

Central BH is very cool, 30 million Mo

Center of M31

Edge-on Spiral Galaxy

NGC 891 - we think our Galaxy looks like this

This is an infrared

composite image from

Starburst galaxies

Galaxies which are undergoing rapid phase of star formation

Supernova rate about 10 times higher Many bright stars Fluorescent gas clouds

NGC 4214HST

Starburst Galaxy M82

Radio map is CO which traces H

IR map shows proto-stars

Starburst galaxy M82

X-ray evidence for intermediate mass black hole in M82

High supernova rate makes many smaller black holes, which may merge

Hubble Galaxy Sequence

Ellipticals (round through oval) Spirals (centrally condensed with arms) Barred Spirals (distinct bar shape with bulge)

Spiral Galaxies

Bulges formed over a short period very early in the young universe, perhaps through the collapse of a single cloud of hydrogen or merger of primeval star clusters.

NGC 1232/VLT

NGC 1288

Spiral sequence

SandageHubble Space Telescope

NGC 5838/S0

Spiral sequence

NGC 5689/Sa

Spiral sequence

NGC 5965/Sb

Spiral sequence

NGC 7537/Sbc

Barred Spiral M61

Bar across central region is made of stars, gas, and dust

Small bulge is dominated by a disk of material

Spiral arms begin at both ends of the bar

The bar is funneling material into the hub, which triggers star formation and feeds the bulge

Barred Spiral NGC1365

Optical/Sandage

Optical/HST WFPC2

IR/HST NICMOS

Irregular Galaxies

NGC 4753/I0

Sextans A

5000 light years across

Galaxy formation Large galaxy and satellite galaxy form 200 kpc portion of larger simulation at NCSA

Full simulation followed 262,144 gas particles and 262,144 dark matter particles (not shown) within a 16 Mpc comoving region. It took 140 hours on a Cray YMP.

Galaxy Evolution

A computer simulation of a flat disk-type galaxy colliding with a dwarf galaxy. The dwarf galaxy cannot be seen, but its gravitational influences trigger the production of spiral arms in the gas-rich disk.

Active Galaxies Quasars

Quasi-stellar radio source. (A radio source that is so far away that it looks like a star.)

Bright nucleus Highly variable Most produce strong X-rays Many have broad spectral lines (104 km/sec) Many QSOs (quasi-stellar objects, with no radio

emission) are often called quasars Seyfert galaxies

Spiral galaxies with bright nucleus Seyfert 2 galaxies are viewed through gas disk

Active Galaxies Radio galaxies

quasars with radio emission (original quasars) some have two lobes, connected by jets some are wildly variable and have X-rays not especially bright in visible light often giant elliptical galaxies

BL Lac objects narrow lines highly polarized radio sources

Blazars wildly variable, have X-rays and gamma-rays quasars viewed down the jet axis

Unified Model of AGN

All AGN are the same: central BH plus disk and jets

Differences in lines, jets, & spectra are due to different viewing angles

Also possible that BHs are being fed at different rates

Seyfert Galaxy NGC 7742

Bright nucleus 3000 light years across 72 million light years away

Centaurus A/Optical

Giant elliptical galaxy

Dark dust lane obscures the central region

Centaurus A/Radio

Double Lobe Radio Galaxy

Image shows radio lobes superposed on optical image

Central black hole must be producing radio jets and lobes

Centaurus A/X-ray

X-ray image from Chandra

Bright nucleus can be seen in center at location of black hole

Small jet to lower right ends in shocked region

Centaurus A/IR IR map shows a

second galaxy (barred spiral) hiding inside Cen A’s dust lanes

Elliptical’s gravity helps barred spiral maintain its shape

Material funneled along the spiral's bar fuels the central black hole which powers the elliptical's radio lobesSymbiotic relationship

M87 Optical

Giant elliptical galaxy At center of Virgo

cluster Many globular clusters

surround it Little dust and gas in the

galaxy 50 million light years

M87 HST Movie

M87 Optical Jet

HST IR and UV composite

Globular clusters also seen

Note shock waves and knot patterns in jet

Bright point at central black hole

M87 Radio Jet

Central black hole is making jets

Jets are making bubbles of hot gas

Bubbles are as big as 200,000 light years

Smallest resolution VLBI image is 0.2 light years

M87 X-ray and radio

X-ray contours on radio image

High energy emission from central black hole

ROSAT X-ray data

X-ray Quiet AGN

Luminous optical nucleus yet X-ray quiet

M87 - X-ray Quiet AGN?

Elliptical galaxies with known supermassive black holes from optical data

Advective accretion means that matter flows over the event horizon without making many X-rays due to the lack of a hot accretion disk

Gamma-ray Quasars

3C 279 is a very bright, repeatedly flaring gamma-ray source, seen at MeV - TeV energies

3C273 is much

brighter at optical

energies

Blazar movie

Shows rotating black hole in the center of Active Galaxy, which is emitting relativistic jets of material

Blazar is a quasar that is aiming its beams directly at us

Most distant QSOs Redshift record is now around Z=6.5 Sloan Digital Sky Survey

Z = 5.0 Z = 4.75Z = 4.9

Collisions and Mergers

Note: galaxies do not make noise when they collide!

Galaxy Collision

Galaxy Collisions, Part 2

Cartwheel Galaxy

Wheel shape was formed from collision of two galaxies

Bright stars are forming at the edges of the wheel (105 light years in diameter)

Intruder galaxy is no longer visible

This is from HST

Active Galaxies and Jets

What do Active Galaxies look like when viewed from different distances?

Web Resources

Astronomy picture of the Day http://antwrp.gsfc.nasa.gov/apod/astropix.html

Imagine the Universe http://imagine.gsfc.nasa.gov

M87 radio images http://www.aoc.nrao.edu/~fowen/M87.html

Space Telescope Science Institute http://stsci.edu

Sloan Digital Sky Survey http://www.sdss.org/

Web Resources

A. Ptak’s intermediate mass black hole in M82 http://astro.phys.cmu.edu/~ptak/m82/

T. di Matteo’s X-ray quiet AGN http://www-glast.sonoma.edu/HEADmeeting/tuesday/index.html

ROSAT X-ray images http://wave.xray.mpe.mpg.de/rosat/calendar/2000/oct

NCSA’s Unveiling the Hidden Universe http://www.ncsa.uiuc.edu/Cyberia/Bima/BimaHome.html#Unveiling

Web Resources

NCSA M82 images http://www.ncsa.uiuc.edu/Cyberia/Bima/ExtraGal.html

Galaxy Formation Movie from NCSA http://www.ncsa.uiuc.edu/Cyberia/Cosmos/TheWorksMovies.html

March 18, 2003Lynn Cominsky - Cosmology A3501 Professor Lynn Cominsky Department of Physics and...

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