The Square Kilometre Array and Radio Astronomy: Canada & - - PowerPoint PPT Presentation

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The Square Kilometre Array and Radio Astronomy: Canada & - - PowerPoint PPT Presentation

Sep 20, 2022 211 likes •925 views

The Square Kilometre Array and Radio Astronomy: Canada & Australia Kevin Vinsen (ICRAR, UWA) Spot Quizzes / Guess Tests I have some fun spot quizzes just to highlight how big some numbers are. ICRAR 2 Scientific Notation I

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Kevin Vinsen (ICRAR, UWA)

The Square Kilometre Array and Radio Astronomy: Canada & Australia

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ICRAR

Spot Quizzes / Guess Tests

I have some fun spot quizzes just to highlight how big some numbers are.

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Scientific Notation

I promised no hard maths, but you need to understand the numbers I use. Astronomy deals with very large and very small numbers… Distance from Earth to Sun ~ 150 000 000 000 meters Mass of hydrogen atom ~ 0.000 000 000 000 000 000 000 000 001 67 kg

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1.5x1011 meters 1.67x10-27 kg

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Number Scales

A lot of this presentation is about really BIG numbers. Here’s a reminder of the SI Units:

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Prefix Symbol

10n

Decimal Short Example mega M

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1,000,000 Million giga G

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1,000,000,000 Billion 3 billion base pairs in the human genome tera T

1012

1,000,000,000,000 Trillion 1 ly = 9.460 tera kilometers peta P

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1,000,000,000,000,000 Quadrillion 1 petasecond = 31.7 million years exa E

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1,000,000,000,000,000,000 Quintillion 0.43 Es ≈ the approximate age of the Universe zetta Z

1021

1,000,000,000,000,000,000,000 Sextillion Volume of seawater in the Earth's

  • ceans is ≈ 1.369 zettalitres

yotta Y

1024

1,000,000,000,000,000,000,000,000 Septillion The observable universe is estimated to be 880 Ym in diameter.

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Scientific Method

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Hypothesis Theory Testable Yes Yes Falsifable Yes Yes Well substaintiated No Yes Well tested No Yes

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What is Astronomy

Literally: aster = star + nomie = naming Astronomy is the observational scientific study

  • f the universe and its contents.

Astrophysics is the combination of astronomy with theoretical understanding of the processes taking place in astronomical

  • bjects.

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How fast are we moving

The Earth is rotating at 0.46 km/s The Earth moves around the Sun at 
 30 km/s Our Solar System is moving around the Milky Way at 300 km/s Our Galaxy is respect to other galaxies 540 km/s

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Spot Quiz

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For the full SKA

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SKA on one slide

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  • Two phases:
  • SKA1 and SKA2
  • Two telescopes:
  • SKA1-low (~130,000 dipoles)
  • SKA1-mid (196 15m dishes)
  • Three host countries:
  • Australia (Murchison shire)
  • South Africa (Karoo)
  • United Kingdom (HQ)
  • 12 member countries:
  • Australia, Canada, China, France,

India, Italy, New Zealand, South Africa, Spain, Sweden, The Netherlands, United Kingdom

  • 10 Work-packages:
  • Assembly
  • Integration and Verification (AIV)
  • Central Signal Processor (CSP)
  • Dish (DSH)
  • Infrastructure Australia and Africa

(INFRA AU/ INFRA SA)

  • Low-frequency Aperture Array (LFAA)
  • Mid-frequency Aperture Array (MFAA)
  • Signal and Data Transport (SaDT)
  • Science Data Processor (SDP)
  • Telescope Manager (TM)
  • Wideband Single Pixel Feeds (WBSPF)
  • Cost cap at €650M for SKA1
  • Power cap ~5 MW
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Some of our requirements for Phase 1

  • SDP_REQ-289 Maximum science product preservation lifetime.

The SDP shall preserve science data products for not less than 50 years from the start of science operations.

  • SDP_REQ-705 preserved Science Data Product growth rate

The SDP shall support a growth rate of preserved science data products per year of 34 PB for MID and 11 PB for LOW covering at least the science data products of the High Priority Science Objectives

  • SDP_REQ-669 Buffer size

The SDP shall be able to store a minimum of 12 hours (TBC-010) of visibility data (at the maximum data rate) in its buffer (where it is either awaiting processing or being processed) and to jointly image at least 6 hours of visibility data.

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FAST

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Redshift

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Wow! Signal - 1977

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Credit: Big Ear Radio Observatory and North American AstroPhysical Observatory (NAAPO)

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Spot Quiz

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For the full SKA

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How faint are the signals?

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Energy of a pair of falling feathers < 60 microjoules Energy collected by ALL radio telescopes, prior to 2014, less than a pair of falling feathers

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Electromagnetic Spectrum

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H2O, CO2, O2 N2, O2, O3 Radio

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Radio and Optical

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M82 M81 NGC3077

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What Radio Astronomy can see....

HI - Neutral Hydrogen But we can also see over 150 molecules 500+ lines have been identified, but not classified These include:

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  • Water (H20)
  • Hydrogen Sulphide (H2S)
  • Ethyl methyl ether (C2H5OCH3)
  • Ammonia (NH3)
  • Carbon Monoxide (CO)
  • Acetylene (C2H4)
  • Formaldehyde (H2CO)


embalming fluid

  • Methanol (CH3OH) 


wood alcohol

  • Amino acetonitrile

(NH2CH2CN) 
 a simple organic compound

  • Glycoaldehyde

(HOCH2CH2OH) 
 a simple sugar

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Radio Telescopes need a large collecting area

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Radio Photons are Wimps

  • X-Ray photons => 10ev - 100KeV
  • Optical photons of 600 nanometre => 2 eV
  • Radio photons of 1 metre => 0.000,001 eV
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Second Reasons

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A larger aperture has better resolution

∆θ ≈ 1.22λ D ∆θ

∆θ = 1” λ D

Optical 500nm 125mm Radio 21cm 53.37km

  • D

D

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SKA Images

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Direct and Indirect Imaging

  • Direct Imaging
  • The image is projected onto a detector.
  • Examples: your eye, cameras, optical telescopes,

single-dish radio telescopes

  • Indirect Imaging
  • Used where we cannot form a direct image of the
  • bject on the focal plane
  • We infer the properties of the object from certain

characteristics of the received electromagnetic field

  • Examples: interferometry, NMR, ultrasound, PET

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"PET

  • MIPS-anim" by Jens Maus

(http://jens-maus.de/)

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How we build images

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Credit: Tom Oosterloo, ASTRON

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Event Horizon Telescope

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Data Intensity Astronomy

What happens to the data

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Antennas / Digitisers Correlator Science Data Processor Archive

MWA 1.4TB/h MWA 5 PB/y ASKAP 9TB/h ASKAP 5.5 PB/y SKA1-Low 1,800TB/h SKA1-Low 150 PB/y

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Spot Quiz

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For the full SKA

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Size Comparison

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Biggest (so far)

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Little Pluto

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Reality is “weirder” than fiction

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Space is BIG

The nearest planet Proxima Centauri b is 4.24 light years away

  • r 4.24 x 9,460,730,472,580.8 km

  • r 40,113,497,203,742.59 km

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Max Speed 
 (km/H) 39,897 61,436 690,000 Time (Years) 114,696.14 74,483.94 6,631.93

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Saying hello to Proxima Centauri b

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Gravitational Waves

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Neutron Star

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Diameter: 10-30km Mass: 2x Sun (Theory says 3x is the max) Spin: 716Hz -> Once every 8.5s So dense that a single teaspoon would weigh a billion tons

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ICRAR 2019

What is a Gravitational Wave

Gravity

  • Einstein’s General theory of relativity says: gravity is a

manifestation of the curvature of 4- dimensional (3 space + 1 time) space-time produced by matter

  • If the curvature is weak, it produces the familiar

Newtonian gravity

  • When the curvature varies rapidly due to motion of the
  • bject(s), curvature ripples are produced. These

ripples of the space-time are Gravitational-waves.

  • Gravitational-waves propagate at the speed of light.

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ICRAR 2019

Strain

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Strain [(Change of length)/(Length)] : h ~ 10-21 Sensing changes over 4 km to a thousandth the size of a proton

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ICRAR 2019

What it looks like

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ICRAR 2019

Current approach

  • Traditional Signal Processing
  • Noise Whitening
  • Matched Filters

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ICRAR 2019

Whitening

  • Take the Fourier transform
  • Divide by the Amplitude Spectral Density
  • Convert back to the time domain

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ICRAR 2019

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tp-3-[37552 1]: m1: 6.18, m2: 48.01, dist: 1468.13, inc: 1.66
 snr: 3.85, cm: 13.69
 snr bin: [0. 1. 0. 0. 0. 0. 0.], out: [0.34 0.69 0.24 0. 0. 0.

  • 0. ]


chirp mass: [0. 1. 1. 0. 0. 0. 0. 0.], out: [0.47 0.51 0.37 0.03 0. 0. 0. 0. ]

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Spot Quiz

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For the full SKA

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Trappist-1

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Where did we get the term ‘Big Bang’

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Sir Fred Hoyle first coined the phrase 'Big Bang' he did so in order to mock the

  • theory. Hoyle was a firm believer in the

alternative steady state theory which gives the universe no start or end.

Basically Sir Fred was taking the piss out a theory he thought was bl**dy stupid

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What was before the big bang?

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Nothing

  • r

Something

It’s a bit like asking what is North of the North Pole

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How did it start?

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We don’t know

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Galilean relativity

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Einstein's relativity postulates

It required the genius and the courage

  • f Einstein to accept the third
  • alternative. His special relativity is

based on two postulates: All laws of nature are the same in all inertial frames This is really Galileo relativity The speed of light is independent of the motion

  • f its source

This simple statement requires a truly radical re-thinking about the nature of space and time!

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Albert Einstein 1879-1955

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Pythagoras

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The time dilation formula can be shown to result from the fundamental postulates by considering a light clock.

Ticks every time a light pulse is reflected back to the lower mirror

Some consequences: time dilation

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c h t =

tock! tock!

Stationary clock: Moving clock:

c vt h c x h t

2 2 2 2

) ( + = + =

2 2 2 2

/ 1 1 / 1 1 c v t c v c h t − ⋅ = − ⋅ =

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Time Dilation

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Days 0.0 1.00 0.1 1.01 0.5 1.15 0.8 1.67 0.9 2.29 0.99 7.09 0.999 22.37 0.999999 707.11 0.999999999999 707114.60

v c

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What does this mean?

Time in a moving system slows down comparing to a stationary system!

E.g., charged pions have a lifetime of t = 2.56 x 10-8 s, so most of them would decay after traveling ct = 8 m. But we have no trouble transporting them by hundreds of meters!

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No time dilation 8 m 300 m With time dilation π+ π+

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Let’s get slightly weird

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LIGO-G0900422-v1

Einstein-Rosen Bridge

Our Universe Another Universe?

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LIGO-G0900422-v1

Schwarzschild Worm Hole


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Spot Quiz

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For the full SKA

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Where are the Aliens?

Quote from Jill Tarter - ex-head SETI Institute Set the volume of our galaxy to be like the Earth’s oceans which are ≈ 1.369 zettalitres. We’ve sampled 350ml or a Middy and a few shot glasses Our Galaxy: Diameter: 100,000 + light years Star Count: 100 - 400 billion Oldest Star: 13.7 billion years

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The Drake Equation

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N = R* × fp × ne × fl × fi × fc × L

Name Symbol Pessimistic Optimistic

The rate of formation of stars in the Milky Way galaxy

R* 7 7

The fraction of those stars with planets

fp 60% 60%

The number of earth-like planets in each planet-bearing star system

ne 0.5 2

The number of habitable earth-like planets (or locales) where life does develop

fl 1% 50%

The fraction of planets (or other life-bearing locales) where life exists that intelligence develops

fi 1% 1%

The fraction of intelligent species that eventually develop a "high technology" communicative ability

fc 10% 50%

The lifetime of high-tech communicative civilisations

L 100 100,000

Advanced extraterrestrial civilisations in the Milky Way galaxy

N 0.021 2,100

How close are the civilisations

87,000ly 1,876ly

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AstroQuest - we need your help

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https://astroquest.net.au https://www.icrar.org

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AstroQuest

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Is AI a threat

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At the moment it is able to do one thing well. Like my GW work. It can’t, as yet, learn new things. Nobody has developed a general reasoner (yet). Nikki’s service dog is more capable of learning new things than current AI systems. He has a biological general reasoning ability.

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Why we need STEM

We must equip ourselves to be critical thinkers. We should and must question fake science

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What Radio Astronomy has given back to the World

Imaging faint signals Amazingly accurate clocks

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Finally…

As children, we all live in a world of imagination, of fantasy , and for some of us that world continues into adulthood.

  • Jim Henson (

1936 - 1990)

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Any Questions

I’m “hard of hearing” - so please speak clearly.

Contact me at kevin.vinsen@icrar.org

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