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Orders of Magnitude:
the impact of high resolution astronomy
Ethan J Schreier
Associated Universities, Inc.
Massive Black Holes in Galaxies
Symposium in memory of David Axon
University of Sussex
18-19 April 2013
Outline
• Some remarks about high resolution in astronomy
• A personal history of increasing resolution, new wavelengths: observations
of Centaurus A
• Some of the highest resolution observations in astronomy - VLBA
• Status report on ALMA, one of the newest instruments in astronomy
• Some personal remarks on Dave Axon
Importance of Resolution
resolution vs wavelength
• New techniques  new discoveries
• New domains  new phase space
• orders of magnitude
• Resolution as a new domain
• λ/D
• Xray – optical –infrared –radio
HST
VLBA
ALMA
Resolution vs time
RadioAstron
350,000 km apogee
GBT
Resolution vs time: a history of radio astronomy
from K.Kellerman
Cen A = 5128: a personal resolution history
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optical nebula known since 1826
double nebula shape 1847
one of first radio sources, 1949
optical-radio ID 1954 (B&M)
identified with Uhuru x-ray source 1971
X-ray jet discovered w/Einstein 1979
jet confirmed with VLA 1980
Cen A: Radio jet
CEN A: X-ray jet
Cen A: Imaging the center with HST
20 cm VLA radio map
Gray-scale continuum-subtracted Paα image
ALMA molecular spectra towards the Cen A black hole
Juergen Ott (NRAO)
The many faces of Centaurus A: imaging from 400kpc to 0.1pc
VLBI. Muller etal
Radio (150MHz) + X-ray
(ROSAT Survey, Stefan
2013, MNRAS)
Optical/Radio/X-ray
VLBA: highest resolution in astronomy
• VLBA’s resolution has produced remarkable results across
astronomy
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Distant galaxies and the cosmological distance scale
Active galaxies
Galactic structure
Stellar structure
Solar system
NGC 4258: Cosmological Distance Ladder
Bar and spiral structure legacy survey (BeSSeL)
• Goal: determine structure and
kinematics of the Milky Way
Galaxy
• Perform astrometry on masers
in star forming regions
• Water masers at 22 GHz
• Methanol at 11 and (soon)
6.7 GHz
• Early results have improved
measurements of the distance
to the Galactic Center and
rotational velocity
• R0 = 8.4 ± 0.6 kpc
• 0 = 254 ± 16 km/s
One of 10 top-cited astrophysics papers between 2009 and 2011
M87 jet in action
Precessing microquasar SS433
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BH or NS accreting matter from companion star
The jet precesses with a 164 day period (movie spans ¼ cycle)
VLBA observations at 15 GHz yield 3 AU resolution (at d=5 kpc)
Jet material travelling at 0.26c
– contains baryons
– consistent with ballistic motion
Movie: Mioduszweski et al. in prep.
Circumstellar SiO Masers: TX Cam
• 557 day brightness period
(pulsations of atmosphere)
• first direct observation of stellar
atmosphere motions
(other than sun)
VLBA Astrometry of Cassini at Saturn
• measurements between 2006 and 2009;
• ~0.3 mas (2 km) relative to quasar
reference frame (ICRF).
• contributing to new DE422 planetary
ephemeris
• ultimately reduce uncertainty in
Saturn’s position by a factor of 3;
implications for
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spacecraft navigation
solar system dynamics
general relativity research & pulsar timing,
frame ties connecting the solar system to
ICRF
Jones et al., 2011, ApJ, 141, 29
ALMA: the newest high resolution
millimetersubmillimeter observatory
• Resolution: similar to HST, but at much longerλ
– thus far limited by short baselines
– ultimately: mm/submm VLBI with ALMA
• Status: All 66 antennas & all receivers in Chile
– 60 antennas accepted (25 NA, 16 EA, 19 EU); 57 through AIV
– Correlator, roads accepted; high site on permanent power supply
DV25 to 1.5km baseline
ALMA Status
• 2012: completed Cycle 0 Early Science
– “The First Year of ALMA Science” – 12/2012
• 199 participants; 43 ALMA results presented
– 22 papers appeared in 2012 containing ALMA data
• 2013: initiated Cycle 1 observing, 2x antennas, 2x resolution
– 1131 proposals were received, with 197 achieving ‘highest’ priority
status (cf. HST!)
Feb 2013 also:
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year 30 of AUI/NRAO involvement in a
Millimeter Array
year10 of NA-Europe agreement to build
ALMA
ALMA on budget (est. 2005), nearly on time
ALMA Inauguration
13 March 2013
Congratulations from Intl. Space Station
President Pinera and NSF Director Suresh
Collecting Area & Baselines
ALMA
ALMA
Full Science
50+12+4 (1225+66)
CARMA
23 (253)
8 (28)
Cycle I
32+9+2 (496+36)
6 (15)
Circles Show Collecting Area (sensitivity)
Captions give # of antennas and # of baselines (fidelity)
Frequency Coverage
Early Science (now)
Full Operations
Completed
• B4: 18 of 73
• All: ~2014
• B5: most of 6
• All: ~2018
• B8: 28 of 73
• All: ~2014
• B10: 6 of 73
Frequency [GHz]
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6
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ALMA Early Science Begins: ‘Antennae’ Science Verification Data
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Inset: ALMA’s first mm/submm
test views, in 3mm (orange),
1.3mm (amber; detail
surpassing all previous at these
wavelengths.
Large Image: Multiwavelength
composite of interacting
galaxies NGC 4038/4039, the
Antennae, showing their
namesake tidal tails in radio
(VLA HI: blues), past and recent
starbirths in optical (whites and
pinks), and a selection of
current star-forming regions in
mm/submm (orange and
yellows).
Gas Flows through a Protoplanetary Disk Gap
• HD142527: IR data shows 10 AU inner disk, 140 AU
gap, disrupted outer disk 140+ AU
Disruption attributed to unseen planetary mass body(s)
Artist Concept
at ~ 90 AU
ALMA Band 7
• ALMA sensitivity and spatial resolution enabled images ALMA data cube
of dense gas in gap-crossing filaments, along with
diffuse CO gas within gap (Cassasus et al. 2013)
 Observation explains how the observed high
accretion rate may be maintained
 Dynamical models suggested outer disk gas could
be channeled by putative protoplanets through gapcrossing bridges feeding the inner disk: these
observations support these models
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ALMA: Imaging gas in a proto-planetary disk
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Rosenfeld et al. 2012 image the CO in TW Hya archtypal protoplanetary disk
with information down to scales of 2AU
The data are reasonably modeled by a warped disk on AU scales. Such a warp
could be generated by an embedded massive planet in the disk.
CO observations
and modeling of the
warped disk in the
protoplanetary disk
TW Hya
ALMA View of the Young Solar System Analog Disk Around AU Mic
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Two distinct debris emission components
– central peak
• Stellar photosphere plus asteroid-like belt at a few
AU? compatible with no excess < 25 μm
– outer dust belt
• extends to R=40 AU, to the break in scattered light
profile
• appears truncated, reminiscent of classical Kuiper Belt
initial condition? or result of dynamical interaction?
• rising surface density profile: S ~ r2.8 inner collisional
depletion?
• no detectable asymmetries in structure or position
offset limit compatible with presence of Uranus-like
planet
Hypothetical view with planet
and moon
Macgregor et al 2013
2013 ApJ 762 L21
The Formation of Planetary Systems: Fomalhaut
ALMA Cycle 0 Reference Image
No data
Band 7 (870 μm)
Dust Continuum
Dust ring
Location of
Fomalhaut
Coronagraph
mask
Scattered
starlight
No data
Goal: Cycle 0 project (191) to
measure emission from
known circumstellar
material and potentially
circumplanetary dust near
the planet Fomalhaut b
using the compact (3hrs)
and extended
1.5” x configurations
1.2”
(Boley,
Corder, Dent,
BoleyPayne,
et al. astroFord, Shabram)
ph1204.0007
20 arcseconds ~ 150 AU
ALMA: imaging cool gas during massive galaxy formation
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[CII]158um: best tracer of cool atomic
gas at high z
ALMA with 16 antennas in 20min at
340GHz => already deepest
observations by factor 10 at these
frequencies!
Dust continuum and [CII] 158um
emission from canonical starburst
group galaxies, B1202-0725 at z=4.7
Three galaxies detected, including an
FIR-luminous quasar, a hyper-starburst
galaxy, and a normal star-forming
galaxy => Early massive galaxy
formation in merging, starburst group
Dust 340GHz
rms = 0.1mJy
[CII]
JVLA and PdBI CO and [CII] spectra and images of
HDF850.1 at z=5.183 emitting galaxies (Wagg et al.
2012)
ALMA: Nitrogen in the Early Universe
Coppin et al. 2009
• Nitrogen is secondary element, produced in
low mass stars => abundance rise in universe
expected to lag that of O and C
• Spectrally traced by [N II] lines at 122 and 205
microns, which emit at about 5% of [C II]
intensity in local universe
• ALMA observations of [N II] in J03329.4, a
starburst submillimeter galaxy at age of 1.27
Gyr (z=4.75)
– [N II]/[C II]~0.043 suggests solar nitrogen
abundance (cf. 0.05 ratio in M82) Nagao et
Visible, NIR/radio, FIR images
Coppin et al. 2009
J03329.4 Spectral energy distribution
Nagao et al. 2012
al. (2012)
ALMA Image, Spectrum
High Redshift SubMillimeter Galaxies
(Karim et al MNRAS arXiv:1210.0249v1)
• 126 LESS* sources observed with ALMA at 870μm
– 3x deeper, 10x higher angular resolution, integration time ~120 s
• 99 sources detected in 88 fields
– significant multiplicity found in brightest sources at 0.2” resolution
• ALMA IDs previously unidentified SMGs; bright emission lines CII =>z 4.4
*LABOCA Extended Chandra Deep Field South Submillimeter Survey
High resolution in
spectroscopy!
Summary
• Have had the privilege of working on many projects in my career, spanning
new domains
• Have personally seen what increased resolution can do: spatial, spectral,
temporal, eg
– Time resolution of UHURU
– Spatial resolution of Einstein/Chandra, Hubble
– Spectral resolution of ALMA (and spatial)
• Have also had the privilege of meeting and learning from many new
experts, in different domains; many of these became friends
• Dave Axon showed up at STScI just when I needed to learn something
about infrared astronomy… it was great working with him, learning from
him, becoming friends, and finding excuses to meet in Italy…
Acknowledgement to NRAO colleagues who contributed inputs, including
W.Brissenden, C. Carilli, A.Wootten, J.Ott, K. Kellerman
Also to many collaborators and coauthors of some of my own work summarized,
including at this meeting – A.Marconi, A.Capetti, W.Sparks – and of course D. Axon