Science with SKA:

The SKA will provide continuous frequency coverage from 50 MHz to 14 GHz in the first two phases of its construction.

A third phase will then extend the frequency range up to 30 GHz.

•Phase 1: Providing ~10% of the total collecting area at low and mid frequencies

•Phase 2: Completion of the full array at low and mid frequencies

SKA-low array – a phased array of simple dipole antennas to cover the frequency range from 50 to 350 MHz. SKA-mid array –to cover the frequency range 350 MHz to 14 GHz. SKA-survey array - a compact array of parabolic dishes of 12–15 meters diameter each for the medium-frequency range, each equipped with a multi-beam, phased array feed with a huge field of view

• SKA1-low (Aus)

• SKA1-mid (SA)

• SKA1-survey (Aus)

SKA1-low• Australia

• Main driver: highly redshifted 21 cm HI line from the Epoch of Reionization and earlier

– pulsars, magnetized plasma, extrasolar planets

• ~250000 antennas

• 50-350 MHz

• 1 km radius core

• 45 km maximum baseline

• 20 deg2 field of view

SKA1-mid• South Africa• pulsars, nearby to mid-z

HI line, high sensitivity continuum sources

• ~250 15m dishes (Meerkat+SKA1 dishes)

• 0.35-3 GHz; ready for additional receivers

• ~100 km maximum baseline

SKA1-survey

• Australia• survey large areas of sky in

line and continuum, transients• ~100 15m dishes

(ASKAP+SKA1 dishes)• 0.6-1.7 GHz• ~25 km maximum baseline• PAF (Phased Array Feed)

Sensitivity + Survey Speed: 3 days to do survey like NVSS ( ~ 10 months VLA over 3 years)

On 18 August 2014, Philip Diamond, Director General of the SKA Organisation, visited the 54th Research Institute of China Electronics Technology Group Corporation (CETC54) in Shijiazhuang, about 300km south west of Beijing to see a complete prototype SKA antenna

The Chinese antenna is an offset Gregorian dual reflector. The main and sub reflectors were made of Carbon Fiber Reinforced Polymers (CFRP), based on single piece panel and surface metallizing technology. The main reflector size is 18m × 15m, the sub reflector size is 5m × 4.7m.

Hubble Deep Field with the SKA

HST SKA

SKA 8 hour integration (simulation by

Hopkins et al.) : 2200 sources

Star formation history of the Universe Star formation vs nuclear activity Star formation history of the Universe Star formation vs nuclear activity

HDF simulation based on source counts : Starburst are blue, AGN are red. A beam of 0.1” is needed to minimize confusion. HDF simulation based on source counts : Starburst are blue, AGN are red. A beam of 0.1” is needed to minimize confusion.

Key Science Projects

Origin of the Universe : 1. Formation of first objects/EoR 2. Evolution of galaxies/ Cosmology/ Dark energy Fundamental Physics : 3. Pulsars/ General Relativity/ Gravitational Waves 4. Cosmic Magnetism

Origin of life : 5. Cradle of life and intelligent life

Hague: 6 Feb B.J.Boyle 13

Probing the Dark Ages

COSMIC HISTORY OF THE UNIVERSE

The Dark AgesEra of the Universe

300 000 - 1 000 000 000 yr after the Big Bang during which the first stars and

galaxies formed

Hague: 6 Feb B.J.Boyle 14

Probing the Dark Ages

18.316.114.513.212.111.210.49.89.28.78.37.97.57.2

SKA RoleDetect and image hydrogen in the dark ages, provide 3D maps of the early cosmic web, shed light on the physics of the formation of the first objects in the

Universe

HI @ z = 5 : ’ = 1.3 m, 240 MHz z = 10 : ’ = 2.3 m, 130 MHz z = 20 : ’ = 4.4 m, 68 MHz

CO @ z = 5 : ’ = 1.6 cm, 19 GHz z = 10 : ’ = 2.7 cm, 11 GHz z = 20 : ’ = 5.5 cm, 5.5 GHz

20 h exposure per pointing, 400 pointingswith 50o field of view (HI, conservative) -> 1 yr

The Nature of Dark Energy

(3.5% HYDROGEN)

Composition of the Universe

Distribution of galaxies in the sky have a

characteristic lenght scale which depends on models of dark energy

SKA RoleLocate and measure spatial distribution of

galaxies via their hydrogen emission

Galaxies/cosmology/dark matter/dark energy

The Nature of Dark Energy

(3.5% HYDROGEN)

35.000 galaxies in 3D space to z ~ 1.5 in a 4 h pointingAll sky survey : 109 galaxies

X 1000 Volume improvement

Weak lensing

-- Planck-- EUCLID

Galaxies/cosmology/dark matter/dark energy

Fundamental Physics: How Gravity works

Pulsars have extreme physical properties:highest gravitational fields: 200000 x solarmost accurate known clocks : 10-9 s

Physics may be different in strong GR

SKA role:Blind survey will find 20 000 pulsars in our Galaxy-many in binary systems andexotic systems1000 millisec pulsars

Fundamental Physics: How Gravity works

Identify and time pulsars with nano-second accuracy

Sensitive gravity wave

detector

Test GR around Black

Holes

• “Find them!”• “Time them!”• “VLBI them!”

-- LIGO -- LISA

Magnetism is one of the 4 fundamental forcesMagnetism is one of the 4 fundamental forces

Magnetic fields are crucial in:Magnetic fields are crucial in:– Star, galaxy & large scale structure formationStar, galaxy & large scale structure formation– turbulence & gas motionsturbulence & gas motions– acceleration & propagation of cosmic raysacceleration & propagation of cosmic rays

Fundamental & unsolved problem:Fundamental & unsolved problem:– Exotic origin (phase transitions, strings)Exotic origin (phase transitions, strings)– Seed fields (turbulence, instabilities)Seed fields (turbulence, instabilities)– AmplificationAmplification

The Origin of Cosmic MagnetismThe Origin of Cosmic Magnetism

Magnetic Fields role in star formation?

SKA roleSKA role

The Origin of Cosmic MagnetismThe Origin of Cosmic Magnetism

Very powerful in the detection of total intensity and polarized emission and in RM measurements

First detailed 3D picture of cosmic magnetic field:First detailed 3D picture of cosmic magnetic field:– Polarization studies of 100 000 000 sourcesPolarization studies of 100 000 000 sources– 10000 x improvement10000 x improvement

•SKA: “instant” RMs and position , σP 0.1 microJy, 100 h obs

= 1.4 GHz, = 400 MHz

- for P = 1 μJy : 2.5o, RM 2 rad/m2, - for P = 10 μJy : 0.3o, RM 0.2 rad/m2

The Cradle of LifeTest conditions for life elsewhere in the Universe

- Image proto-planetary disks in formation, movies, composition- Probe the ‘Habitable zone’ in disks (mas resolution)- Detect complex molecules

- Search for Extraterrestial Intelligence: Airport radars @ 50 l.y. 500 stars Ionospheric radar @5000 l.y. 600 000 000 stars

Exploration of the unknown :

Pathfinders

LOFAR : EoR, magnetism, survey

eMERLIN : galaxy evolution (eMERGE)

Precursors

ASKAP : galaxy and BH evolution, LSS, stars and stellar systems, magnetism (EMU, POSSUM)

MeerKAT : Pulsar Timing, HI survey, SFG and AGN

Murchison Widefield Array (MWA)

Jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004).

SKA1 will enable such studies for large samples of jets, while VLBI observations involving SKA1 will provide the sensitivity for pc-scale imaging, and the full SKA (with its extraordinary sensitivity and dynamic range) will allow us for the first time to resolve and model the weakest radio structures in the most powerful radio-loud AGN.

in particular Band 5 receivers in VLBI mode (Paragi et al. 2014) will provide ∼ milliarcsecond resolution, which corresponds to parsec ∼scales for a broad redshift range. The polarization capabilities will be particularly relevant

Very Long Baseline Interferometry with the SKA

Zsolt Paragi, Leith Godfrey, Cormac Reynolds, Maria Rioja, et al.

Adding VLBI capability to the SKA arrays will immensely broaden the science of the SKA, and it is entirely feasible. SKA-VLBI can be initially implemented by providing phased-array outputs for SKA1-MID and SKA1-SUR, and using these extremely sensitive stations with other radio telescopes, and in the full SKA by realising a distributed configuration providing baselines up to thousands of km, merging it with existing VLBI networks. The motivation for and the possible realization of SKA-VLBI is described in this paper.

Flight Cagliari-Bologna, after the EVN symposium