The Invisible Universe

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The Invisible Universe
Fred K. Y. Lo
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The Visible Universe
Expanding Universe! 99 galaxies near and
far 1 quasars Farthest ones when the universe
was lt1/5 of current size. Mostly
star-light from nuclear fusion
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A galaxy 100 billion stars
Super-massive Black Hole?
Sun
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Electromagnetic Radiation
Wavelength
Invisible Universe There is a lot more to the
Universe than meets the eye!
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Radio Astronomy's Beginnings

• Jansky 1932 Discovered radio waves from the
  center of Milky Way

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VLA Very Large Array (1980) Plain of San
Augustine, New Mexico
27-antenna array Extremely versatile Most
productive telescope on ground
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Center of the Milky Way
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Radio Galaxy Cygnus A
VLA Image of Radio Wave from Cygnus A
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Interacting Galaxies

• Optical image (left) shows nothing of the
  Hydrogen gas revealed by radio image by VLA
  (right).

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• Milky Way

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Star light Heat Radiation
Radio ?????
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Important source of Radio Waves Non-thermal
(Synchrotron) Radiation
Radio wave
High Energy Electrons moving in a Magnetic Field
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Sources of Radio Emission

• Synchrotron radiation of relativistic electrons
  in magnetic fields High Energy particles
• Ionized gas Sources of UV radiation
• Atoms and molecules Cold Interstellar space
• Dust emission Birthplace of stars

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Radio Astronomy The Radio Universe (Developed
rapidly after WWII due to radar techniques)

• Radio Galaxies, Quasars Super-massive
  Black-holes
• Cosmic Microwave Background Radiation (1978)
• Remnant Heat of the Big Bang
• Pulsars (1974) Neutron Stars
• Binary pulsar (1993) Gravitational Radiation
• Molecular Clouds
• Birth place of stars and planets
• Astro-chemistry Amino Acids in Space?
• Year Nobel Prize of Physics awarded

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The Universe is Expanding
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Expansion of the Universe
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Origin and Fate of the Universe
? ?/?(crit)
Open (? lt 1)
Flat (? 1)
Closed (? gt 1)
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Big Bang Cosmology

• Universe was dense and hot
• Temperature of the Universe cools as Universe
  expands T ? 1/R
• Temperature is now about 3K (predicted in 1948)
• Heat should be seen as microwave from all
  directions
• ? Remnant Heat of Big Bang !
• 1964 Penzias and Wilson

Nobel Physics Prize 1978
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Cosmic Background Explorer(1989)
Temp. 2.725K (Homogeneity)
Dipole (Motion of Milky Way) ?T0.0034K
Anisotropy (Density Variation) ?T0.000018K
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Wilkinson Microwave Anisotropy Probe (2002) 96
of Universe Content Invisible (unknown!)

• WMAP satellite
• Detectors built by NRAO

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Wilkinson Microwave Anisotropy Probe (2002)
Space curvature is Flat!96 of Universe Content
Invisible (unknown!)

• WMAP satellite
• Detectors built by NRAO

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High Resolution Interferometry

• Resolution ? ?/D
• 5 cm/100m 2 arc-minute
• Uses smaller telescopes to make much larger
  synthesized telescope
• Maximum distance between antennas determines
  resolution
• VLA 22-mile diameter radio telescope
• 5 cm/22 miles 0.3 arc-second
• Aperture Synthesis Nobel Prize 1974 (Ryle)

D
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VLA Very Large Array (1980) Plain of San
Augustine, New Mexico
Array Operations Center, Socorro, New Mexico
27-antenna array Extremely versatile Most
productive telescope on ground
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Very Long Baseline Array

• 10 ? 25m antennas
• Continent-wide 5400-mile diameter radio
  telescope
• 6 cm/5400 miles
• 0.001 arc-second
• Highest resolution imaging telescope in
  astronomy
• 1 milli-arc-second reading a news-paper at a
  distance of 2000 km

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Radio Galaxy Zooming In

• VLA, VLBA combine to reveal structure with
  increasing details

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Energy Source of Radio Galaxies?

• Normal Galaxies
• Total luminosity 1011 Lsun
• 1011 stars in a galaxy of size 105 ly
• Radio Galaxies and Quasars gt 1012 Lsun
• Non-thermal radiation not star-light
• Very compact ? 1 light-year
• Milky way 100,000 light-year across
• Jets energy flow directional
• Super-massive Black Hole paradigm
• Release of gravitational binding energy as matter
  collected in an accretion disk falls into BH
• ?U GMm/R (GM/c2R) mc2
  (Rsc/2R) mc2
• where R radius of last stable
  orbit

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Super-massive Black Hole Accretion Disk
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Micro-quasars
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Radio Galaxy Cygnus A
Similar jets to the nearby micro-quasars, but
distance is so great that motion cannot be
measured so easily
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Radio Galaxies and Quasars
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History of the Universe
Age of the Universe 13.8 Billion years
Universe became transparent (CMB)
First stars formed at 200 million years
Oldest known quasar at 800 million yrs
Hubble Deep Field out to 2 billion yrs
How stars form? ? How galaxies form?
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Interstellar Space Dust and Molecules
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Stars form in Dust Clouds
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Proto-stars and Proto-planetary Disks
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Disks and Jets around Young Stars
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Interstellar Medium
Interstellar Dust and Molecular Clouds,
where stars form
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Stages of Star Formation
outflow
Adapted from McCaughrean
infall
x1000 in scale
Cloud collapse
Rotating disk
Planet formation
Mature solar system
Scenario largely from indirect tracers Directly
observable via mm/submm wave ? ALMA
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ALMA Atacama Large Millimeter Array North
America/EuropeJapan joined in 2004
Operational 2012 (Early Science in 2009)
64 ? 12-m telescopes at 5000m ACA 12 ? 7-m
4 ? 12-m 3 additional frequency bands
Al Wootten, ALMA/US Project Scientist
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ALMA Specifications
Antennae 64 ? 12 m collecting area gt 7000
m2 Configurations 150 m 14 km resolution
(300 GHz) 1.4 0.015" Frequency 31 950
GHz wavelength 10 0.3 mm Receiver
sensitivity close to quantum limit Correlator 1
6 GHz / 4096 chan. Site Chajnantor _at_5000m

• 10 x Hubble resolution
• 10 x current sensitivity

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Absorption of ?mm radiation by water in the
atmosphere ? High Desert
?1.5 mm
?300 ?m
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Salar de Atacama
Cerro Chajnantor ALMA
San Pedro de Atacama
Salar de Atacama
0.55, 0.8, 1.6 mm Landsat 7, 2000 February 12
NASA/GSFC
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Birth of Stars and Planets
Cold forming planetary systems dark in HST images
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Birth of Stars and Planets
Evolutionary Sequence Molecular Cloud Core to
Protostar (104 yrs) to Protoplanetary Disk
(to 106 yrs) to Debris Disk (to 109
yrs)
Wilner et al. 2002
Wolf and DAngelo 2005
Lodato and Rice 2005
25AU
5AU
160 AU
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High z Starburst Galaxies
(LFIR1.61012 Lsun)
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Distant Galaxies Bright in ?mm
M82 from ISO, Beelen and Cox, in preparation
50 ?Jy
ALMA Bands
Optical
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ALMA Early Galaxies
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Ground BreakingALMA Operations Support
Facility9 November 2003
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ALMA Major construction project, civil,
mechanical, electronic, software, international
relations!
To AOS
OSF Site
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Site
AOS
OSF
ALMA Camp offices
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View from 18km42 km of road CH23-OSF-AOS
View West
View East
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Environment
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Electronics Prototypes
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Receiver
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First quadrant of Correlator
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Antenna Test Facility at VLA site, NM
AEC
VertexRSI
Mitsubishi
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ALMA Schedule

• 19982002 Design and Development
• 2003 Bilateral Agreement between NSF and ESO
  signed
• 2003 Ground Breaking
• 2003/4 Completion of Proto-type Antennas
• 2004 Japan joins
• 2007 First production antenna in Chile
• 2009 Early science operation
• 2011 Construction ends
• 2012 Science operation begins

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Outstanding Questions in Astronomy

• What is the rate of expansion of the Universe?
• What is Dark Matter and Dark Energy?
• How are stars and planetary systems formed?
• How and when are galaxies and quasars formed
  first?
• Where is the origin of the chemistry of life?

? THE INVISIBLE UNIVERSE Much more than meets
the eye!
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NRAO Open Sky PolicyA System of Complementary
Telescopes
ALMA in 2012
Total number of staff 580
Joint ALMA Obs.