Steve Rawlings

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SKADS-DS2Sky and Data Simulations

• Steve Rawlings Hans-Rainer Klöckner (Oxford)

SKADS meeting Perth 2008
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SKADS DS2

• To establish the scientific requirements in
• a quantitative manner to establish the
• capabilities of the observing system
• necessary to deliver them and thus to
• derive a quantitative set of design
• specifications.
• ? Dish versus AA

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SKADS interactions
SKADS concept
Sky Simulation (DS2T1)
WIKI
Telescope Simulation (DS2T2)
Network Sims costing (DS3)
Technology Demonstrator (DS5 DS6)
Technology Development (DS4)
Pathfinder (LOFAR, KAT,ASKAP, MWA)
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Simulating the Radio Sky

• The need for sophisticated simulations
• - demonstrate SKA can beat systematics
• - drive technologies that generate
  transformational SKA science
• SKADS
• - whats been done 2006-2008 and how to use
  it
• - what will be done before mid-2009
• - what wont be done by then, and future
  plans

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Back of Envelope
Abdalla Rawlings (2007)
Important to keep adding to the science case
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Measurement of Neutrino masses and hierarchies
Abdalla Rawlings (2007)

• If Smn is 0.05 eV, SKAPlanck sufficient and
  necessary to measure it, and hierarchy must be
  normal. If Smn gt 0.25 eV, measurement of Nn too!
• With particle physics experiments, prospect of
  evidence for sterile neutrinos or time
  evolution of neutrino mass
• But all based on perfect (10??catalogue) SKA
  survey no longer adequate

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Simple e2e Simulations now inadequate



k
k
w
Sivia Rawlings
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Also, things are moving on

• Spectroscopic All-sky Cosmic Explorer 5 billion
  redshifts over 3/4 sky to z2.5, multi-slit
  near-IR
• Competition/Synergies DUNESPACE (EUCLID)
  M-class (300 MEuro), could be as early as 2017

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Best Technology Solution
Dishes
300 MHz HI at z4
Aeff
800 MHz HI at z0.75 day with dish-SKA to get
multiple P(k) perfect because few x 36520,000/30
500 MHz HI at z2 month with the AA-SKA to
get multiple P(k) perfect because
10x1220,000/250
SPARSE AA CRITICALLY- SAMPLED AA
Frequency
Collecting area below 500 MHz rises as (1z)2 for
sparse arrays, but only worth going to z4
because of sky temperature (Braun 2006) Using
multi-beaming to shape FOV a (1z)4 gives
constant mapping speed, and a plausible FOV at
the lowest frequency
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Technology and Phasing
Cosmic volume (time) x (FOV) x (A/T)2 for radio
HI If we relied on observing time, errors on P(k)
would improve by a factor 10 every 100
years! Technology I increase dish FOV by 100
and dedicate array, 105 galaxies to z0.2 (1
SKA pathfinders HI P(k) by 2010) Technology 2
mass production to increase A/T by 10. 107
galaxies over 20,000 deg2 to z0.75 (10 SKA in
dishes 2015) Technology 3 additional technology
(500-800 MHz). Further increase in A/T and FOV.
109 galaxies to z2 (100 SKA in aperture
arrays 2020). Technology 4 Benefit from
increased processing power as you integrate
(300-800 MHz). gt1010 galaxies to z4 (2020-2030)
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SKADS DS2-T1 Short-Term Deliverables
T0July2006

• Continuum Surveys Oxford, Leiden, (Herts, UCL)
  
• Richard Wilman (Oxford) simulation deliverable
  T018
• Ilse van Bemmel (Leiden) deliverable to be
  finalised (MeqTree Ionosphere module?)
• Line HI Surveys Oxford, Groningen, Swinburne
• Danail Obreschkow (Oxford) simulation
  deliverable T012
• Rense Boomsa (Groningen) deliverable to be
  finalised (High-res HI module?)
• Magnetism Cambridge, Bonn
• Martin Krausereplacement (Cambridge)
  simulation deliverable T018
• Tigran Arshakian (Bonn) deliverable to be
  finalised (Galactic Foreground module?)
• Pulsar Surveys Manchester
• Roy Smits (Manchester), simulation deliverable
  T015
• EOR Paris, Lisbon
• Paola Di Matteo (Paris), simulation
  deliverable T021

PAPER SUBMITTED RICHARD WILMAN
PAPER in prep SEE DANAIL OBRESCHKOW
PAPERS in prep ARIS KARASTERGIOU/ROY SMITS
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Two types of extragalactic simulations

• Line semi-analytic approach (Obreschkow).
• DM haloes from Millennium Simulation
  ascribed HI and H2, star formation rates and AGN
  properties provides insufficient FOV for SKADS
  benchmark
• 4x4 deg2 out to z20 (HI/CO)
• 107 objects
• star-formation continuum OK
• AGN continuum needs work

• Continuum semi-empirical approach (Wilman). DM
  density field evolved under linear theory,
  populated with objects from known radio
  luminosity functions, and with other important
  physics (e.g. non-linear structures, source
  models) pasted on
• currently 20x20 deg2 out to z20
• 2.5x108 simulated sources

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Semi-analytic simulations
Millennium Simulation (Springel et al. 05)
Semi-analytics (De Lucia et al. 06/07)
Post-processing (Obreschkow et al. 08)
Dark matter
Visible matter
Neutral atomic hydrogen
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Physical Model at z0
Obreschkow et al.
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Evolution of HI and H2
?HI
?H2
z2.5
Note link with ALMA
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SKA Predictions
Abdalla Rawlings
Obreschkow et al
No evolution

• In 100 days, phased arrays deliver gt109
  galaxies over 20,000 deg2 to z2 (and multiple
  P(k) to at least z1)

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Continuum and Post-Processing Options
Wilman simulation Lensing model Ben Metcalf
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Francois Levrier OeRC (Oxford)
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SKADS Sims as a Tool
Obreschkow Simulation
WSRT data
Sky simulations will increasingly be checked
against real data
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how does it fit together
Ionosphere / Troposphere
Milky Way
EoR
galaxies, clusters
Jones Matrix
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the concept
EoR
image
cosmological parameter
population of galaxies
catalogue
space density catalogues of astronomical
sources
extrapolate to SKA sensitivities
population of Pulsars distribution
catalogue
Galactic parameter (B, ne)
Galactic foreground
image
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• s-cubed.physics.ox.ac.uk

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Galactic magnetism
Sun Reich et al.
RM
Average of RM blt2deg
PI
Average of PI blt2deg
PA
I
RM too large for l-60deg (not a big problem) PI
fits well
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painting onto
HI
B - field configuration
Groningen
polarization / depolarization (source IQUV
cluster)
Cambridge
Bonn
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Synthesized Catalogue
catalogue
synthesized catalogue
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The MapMaker

• Standalone application in Python
• SQL/Python interface
• Source list query post-processing
• FITS output with annotation file
• 2D images or 3D cubes
• Backend routines to be parallelized and plugged
  into VO

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Measurement Set Generator (De Mesmaeker)

• Python interface to a glish script from T. Willis
• Uses AIPS newsimulator task
• Uses existing configurations or generates random
  ones
• Builds a skeleton MS to be used by MeqTrees

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Configuration Library
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reliability completeness test, crosscheck
number density, clustering
analysis of the continuum sky
Mauch
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Source HI Extraction
R. Auld (Cardiff)
MapMaker
Duchamp
HI cube
Duchamp

• ATNF (M. Whiting)
• Locates sets of contiguous voxels above some
  threshold
• Uses spectral, spatial or wavelet smoothing for
  enhancement
• Very quick (30 minutes for 512 x 512 x 1024 cube
  on a laptop)
• VO-compliant
• Memory and process intensive
• Completeness issues (misses high S/N sources)

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The MeqTrees Software
Developed _at_ ASTRON Smirnov, Noordam with
outside contributions Willis Open source code
Linux / UNIX (virtual machine available) Code
repository for beam shapes, ionospheric models,
... Trees are declared by python scripts and
executed by a C kernel
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MeqTrees Features

• Powerful calibration almost any parameter can
  be solved for
• Fast and smart evaluation on time/frequency grids
• Per-station effects and polarization effortlessly
  included
• Visual assessment of different models via
  difference trees

symmetrical vs asymmetrical beam error level 2
average vs per-station beam error level 0.02

• No parallelization yet limited number of
  sources and antennae
• Uses Measurement Sets but does not generate them
• Input skies are source lists, not images

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Sky through a simulated interferometer
Wilman simulation E-LOFAR simulation (Heywood)
STFC permitting, by2010 Lensing model Ben
Metcalf
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What do we need / have?

• Sky Sim (? cont, HI ?, Pulsar ?, Magnetism ?)
• Analysis (Cont ?, Line ?, Pulsar ? Magnetism ??)
• simulator (? AIPS, ? AIPS , MeqTree ??)
• calibration (? AIPS, ? AIPS , MeqTree ??)
• aperture arrays (OeRC, Amsterdam)
• configuration studies (Bonn)

need concepts to evaluate technical simulations
(dish/AA) sharpen questions
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Concluding Remarks

• - reference skies exist http//s-cubed.physics.ox
  .ac.uk
• - please use them (for SKA simulations and real
  science) and provide feedback
• - e2e data simulations now urgently needed, and
  tools will appear on this same web site as
  they are developed (map-maker, post-processing
  options, configurations, instrument
  simulators)
• - must be linked to functional simulators and
  cost model
• - must keep an eye on synergies with other
  facilities, e.g. EUCLID
• The Future PrepSKA Path2SKA FP7 Sep2
• Path2SKA - being organised by SR on behalf of
  ESKAC - needs to be strongly linked to
  international SKA project