High energy AstrophysicsCosmology and extragalactic

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Mullard Space Science Lab, UCL

15. Cosmology and High Energy Astrophysics in the

future

15. High energy astrophysics in the future

• This lecture:• Future missions and observatories:

– What they areXEUS+Con-X -> IXO ->ATHENA->ATHENA(+)SKAEUSOEuclid

– What they do – What they will tell us

Slide 2

XEUS

• X-ray Evolving Universe Spectroscopy mission• Dreamed up in 1995• “The future of European high energy

astrophysics”• Most sensitive X-ray observatory ever• 2 spacecraft: mirror module separate from

detector spacecraft

Slide 3

Initial concept:

• 6 m2 collecting area at 1 keV – (c.f. XMM 0.25 m2)

• Spatial resolution of < 2 arcseconds

• Spectral resolution of 1-10 eV between 50eV and 30 keV (better than XMM RGS, and imaging rather than gratings!)

Slide 4

Growth on ISS

• After initial 4-6 years, the mirror spacecraft docks with the international space station.

• New mirror segments added to give 30 m2 collecting area at 1 keV

• New detector spacecraft launched with the next generation of detectors

Slide 5

Slide 6

Slide 7

New concept• With space shuttle grounded, space

station was no longer an advantage.– XEUS looked like a dead turkey :(

• Rapidly rethought!

• New technology mirrors use ‘micropore optics’, glass with tiny (mirror) holes like a microchannel plate.

• Much larger mirror now possible for same weight.

• No ISS assembly required.

Slide 9

Revised concept 2005

Slide 8

Objectives:

• Detecting the first massive black holes

• Finding the first galaxy groups and tracing their evolution to today’s clusters

• Evolution of the heavy element abundances

• Absorption line spectroscopy of the intergalactic medium

Slide 10

What did I think it would do?• Crucial aspect in my mind is the

spectroscopy.• Better spectral resolution than XMM with

imaging rather than grating instruments – can go much fainter

• 100 times the XMM collecting area with grown mirrors

• Spectroscopy of not just the brightest X-ray sources.

• We may have been thinking a bit too big – the observatory is supposed to do everything!– Americans could have beaten us to some

important parts of the science with Con-X

Slide 11

Constellation-X

Slide 12

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Constellation X

• Launch 4 identical spacecraft to build up the collecting area rather than launching 1 big spacecraft

• If one goes wrong, the whole mission is only set back a bit (i.e. it has a high level of redundancy).

• About 6 times the collecting area of XMM – more at harder energies

• Similar spatial resolution to XMM– bit like launching a fleet of XMMs

• < 10 eV resolution from 6-10 keV

Slide 14

What would it do?

• High resolution spectroscopy of Fe lines, particularly relativistic lines in AGN.

• Absorption lines from the interstellar medium• X-ray astronomy in general. Bigger and better

than XMM• Not as big, poorer spatial resolution than

XEUS

Slide 15

XEUS + Con-X merged to become International X-ray Observatory in 2009

• Large X-ray observatory, launch date ~2025(+).• Will pick up highly obscured AGN directly from

their X-ray emission.• Single spacecraft, extendable optical bench,

25m long• Like a giant XMM-Newton with a cryogenic

spectrometer.• 2011: US decadal survey didn’t rank IXO high

enough that they are likely to have money for it: IXO was dead.

• ESA hastily went back to studying a European only mission.

Slide 16

March 2011: Athena

• Large X-ray observatory, launch date ~2025(+).• Single spacecraft 12m long – very similar spacecraft

dimensions and layout as XMM-Newton• Key science objectives: strong gravity (relativistic iron

lines) and detecting distant AGN.

Slide 17

• Like XMM-Newton with a larger collecting area split between 2 telescopes and a cryogenic spectrometer.

• ESA down-selection for L1 mission April 2012.

• Lost out to JUICE.

March 2013 on: Athena+

• The call for science themes for the next 2 large ESA missions is out: launches in 2028, 2034.

• X-ray community proposed a new large X-ray observatory, codenamed Athena+.

• 2 m2 collecting area, cryo spectrometer, wide-field imager.• Spatial resolution will be between 2 and 5 arcseconds.• Key science will be intergalactic warm gas, outflows from

AGN. “Most of the baryons and the hot Universe” was what I advocated as the emphasis of the case.

• Announcement November 2013. “Hot and energetic Universe” theme accepted as ESA’s L2 mission.

• Athena (“+” dropped now) anticipated for launch in 2028 (now only 14 years away, and with 18 years now passed since original XEUS concept in 1996).

Slide 18

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Square Kilometer Array

• Huge array of radio telescopes.• Earlier design of 30, 200m diameter radio

telescopes now exchanged for design with hundreds of dishes.

• Will stretch over 8 African countries and into Australia

• Synthesized aperture of 1000 km• Collecting area of 106 m2

• Should be able to see 1 deg2 at 0.1 arcsecond resolution.

Slide 20

Square Kilometre Array

Slide 21

Square Kilometre Array

Slide 22

SKA science• The dawn of galaxies and the reionization of the

Universe, seen in 21cm absorption and emission.

• Measurements of gazillions of redshifts using 21cm line to make incredibly detailed cosmological surveys.

• milliarcsecond imaging of radio galaxy cores with orders of magnitude better sensitivity

• Supernova remnants in starburst galaxies out to 100 Mpc

• Will generate (and have to process) more data per year than the entire Earth does at present.

Slide 23

LOFAR right now.

• While SKA is being planned, there is already a small prototype called the LOw Frequency ARray (LOFAR).

• Main centre is in Holland, but antennas are located in other countries as well, including the UK, to extend baselines and improve resolution.

• UCL has bought into the observatory, collaboratively between MSSL and Physics and Astronomy.

Slide 24

LOFAR central array.Slide 25

Extreme Universe Space Observatory (EUSO)

• Experiment to observe ultra-high energy cosmic rays

• Rather than looking up at the atmosphere from the Earth’s surface, EUSO looks down from above the dark Earth

• huge sky area ~ 160 000 km2.• Images ultraviolet fluorescence from

atmospheric nitrogen in extensive air showers• Sited on ISS (in original proposal at least).• Should detect ~1000 events with > 1020 eV

energy per year

Slide 26

Slide 27

What will it tell us?

• Where do ultrahigh energy cosmic rays come from?

• Are there celestial UHECR ‘sources’?

• Is there a maximum cosmic ray energy?

• Are there high energy cosmic neutrinos?

Slide 28

Just like the fluorescence imagers of Auger observatory HIRES, AGASA, etc but from above rather than from below

Slide 29

Euclid

• The acceleration of the Universe is a very puzzling thing.

• What is this ‘dark energy’ associated with the vacuum?

• Is it Einstein’s cosmological constant?

• A “new” and very big question for astronomers and physicists.

Slide 30

Euclid

• ESA “Medium” mission selected in October 2011.• Will study dark energy using• Weak lensing• Baryon acoustic oscillations• Carries optical and infrared imaging, infrared

spectroscopy.

Slide 33

Euclid

• Its near-IR imaging will go far deeper than VISTA or any other ground-based imaging survey because of the reduced background and lack of atmospheric absorption. The IR imaging isn’t at HST resolution – it isn’t for weak lensing, but for photometric redshifts.

• It will also take near-IR spectra of > 107 galaxies to measure baryon acoustic oscillations.

• Extremely precise tests of dark energy compared to anything that has come before.

Slide 34

Euclid• Weak lensing is at the core of

Euclid. In essence, Euclid will have a wide field optical imager with spatial resolution similar to the HST, but with an exceptionally carefully controlled point spread function.

• Only a 1.2m telescope, but it will take HST-like images of at least half of the extragalactic sky.

• Visible imager consortium led by Mark Cropper of MSSL.

• Extremely ambitious.

Slide 35

Euclid

• US participation in Euclid has been on and off several times. Overall, (arguably) not a positive interaction.

• US decadal plan indicated number 1 priority would be a dark energy mission more ambitious than Euclid to come soon after – WFIRST.

• But NASA was (is?) in big trouble with the cost overrun of JWST. It doesn’t look likely that WFIRST will be launched less than 5 years after Euclid.

• Europe has a really superb opportunity to lead the way in addressing astronomy’s biggest mystery .

Slide 36

• Athena could identify the first quasars and measure the warm intergalactic medium (i.e. most of baryons).

• The Square kilometer array could enable super-high resolution imaging of radio galaxies and measure galaxy redshifts through 21cm line back into the epoch of reionization.

• EUSO (or something similar) could identify what and where the highest energy cosmic rays come from better than any of its predecessors.

• Euclid will probe dark energy to a precision much better than achieved today, to address questions like: is there a cosmological constant, or is dark energy different?

Some key points: Slide 37