Sussex Astronomy

SC HOOL OF MAT HEMAT IC AL AND PH YS IC AL SC IENC E S PHYS IC S AND A S T RONOM Y

INTR OD UCTI ON

The Astronomy Centre at the University of Sussex was founded in October 1965 with a collaboration between the University and the Royal Greenwich Observatory, then at Herstmonceux.

With the precision of 20th century cosmologists we thus celebrate our 50th anniversary in October 2016.

The Astronomy Centre has had a very rich and successful history and, thanks in part to the collaboration with the RGO and running the first Astronomy MSc in the UK, many illustrious astronomers have spent periods of the careers here.

The early history of the Astronomy Centre has been documented well e.g. for the 30th anniversary and on our www pages www.sussex.ac.uk/astronomy/about/history.

To commemorate this 50th anniversary we decided to focus on specific scientific results that had been made at the centre, choosing one result or event from each year. Of course in such a restrictive exercise we will have missed many excellent and exciting results so apologies if we’ve missed your favourite.However, we hope this gives you a flavour of the quality of the research that has been carried out at Sussex for the last 50 years.

Seb Oliver, Chris Byrnes, Ilian Iliev, Antony Lewis, Jon Loveday, Kathy Romer,Mark Sargent, David Seery, Robert E.Smith, Peter Thomas, Stephen Wilkins.

1966T H E C HA N DRE SE KHA R L IMIT

The calculation of the minimum mass star required to form a black hole is refine to include angular momentum.

Lynden-Bell, who worked at Herstmonceux (pictured right). Jeremiah P. Ostriker, Peter Bodenheimer, and D. Lynden-Bell Phys. Rev. Lett. 17Equilibrium models of differentially rotating zero-temperature stars.

1967O P TIC AL VA R I ATI O N O F 3C 446

RGO Astronomers

R. D. Cannon and M. V. Penston (later faculty in the Astronomy Centre) study the radio source 3C 446, now interpreted as a quasar. Quasars are believed to be powered by black holes near the centre of galaxies, and the variability gives us information about their physical environment.

Cannon & Penston,Nature, 214 256-257

1968Q UA S I - S TE LL AR O B J EC T S WI TH AB S O RP TI O N L INES

W.H.McCrea – Evidence for large, cosmological, radio-quiet population of QSOs

I SHALL employ the observational results tabulated by Burbidge and Burbidge, to which reference can be made for further Information on almost all matters relevant to my discussion. The discussion is based on the assumption that the red-shift z In the spectrum of a quasi-stellar object (QSO) is cosmological, apart from a modification mentioned later. Then an immediate inference from the observations is that there exist

many QS0s below the limits of optical or radio detection, the fraction below such limits increasing with increasingz. This is because, on any feasible cosmological model, most QSOs that show relatively small red-shifts would fall below the limits of detectionif transferred to distancescorresponding to relativelylarge red-shifts.

McCrea, W.H.,1968Nature, 218,257

1969G AL AC T I C N U C LEI A S C O LL AP S ED O LD QUASARS

Powerful emissions from the centres of nearby galaxies may represent dead quasars

Lynden-Bell, D 1969Nature.223.690L

1970A PH ILO S O PH Y FO R BI G - BAN G COSMOLOGY

Of the six Astronomy Centre papers in 1970, McCrae was the author of 3. All six AC papers had a single author, compared to 2% of the 230 published in 2015.

McCrae, w., 1970, Nature, 228, 21M

Sir William McCrea 1904-1999

Sketch by Jonathan Hare (1996)

PA PERS PER YE AR

2760 Refereed Journal publications

1971O P TIC AL I DE N TI F IC ATI O N O F CYG N U S X-1

Cygnus X-1 was the first X-ray source widely accepted to be a black hole.

This paper identified and classified the companion blue supergiant variable star (HD 226868) and measured the distance of the entire system to Earth (~2 kpc). In a follow-up paper in 1972 the mass of the black hole was inferred from theradial velocity of the star.

Murdin, P. and Webster, B. L.,Nature, 1971, 233, 110

ESA/Hubble illustration

1972CYG N U S X -1 - A S PEC T RO S C O P I C BI N ARY WI T H A H E AV Y COMPA N ION?

First strong evidence for a black stellar mass remnant.

The radial velocity curve of HD226868 shows evidence of an invisible companion of mass 2.5-6 M� associated with the X-ray source Cygnus X-1.

Webster, B. Louise; Murdin, Paul, 1972 Nature, 235, 37

1973O P T I CAL APPE AR AN C E O F BI N ARY X - R AY SOURCE S

James Pringle

Many of the variable galactic X-ray sources can be explained in terms of mass transfer in a close binary system onto a compact component. X-rays incident on the large star can be absorbed well above the photosphere of the large star andso care must be taken in interpreting optical and X-ray light curves.J E Pringle, Nature, 243, 128, 90

1974AN INFR ARED PH OTO M E T R I C S U RV E Y O F PL ANE TA RY NEBUL AE

Evidence for the formation of dust in the mass-loss outflows from the emission line nuclei of planetary nebulae

An infrared photometric survey of planetary nebulae. Received I974 April 25; revised 1974 May 15.

Cohen, M and Barlow, M.J,1974ApJ, 193,401

1.5m UCSD/UM Telescope, Mount Lemmon, Arizona.

1975I C E AG E S AN D T H E GAL A X Y

The passage of the Solar System through a dust lane bordering a spiral arm of the galaxy may cause a temporary variation of the sun’s radiation and so lead to an ice epoch on Earth.

1975 Nature. 255-607M

C I TATI O N IND IC ES

1976G AL A X Y SPECTRA

New spectra identify many highly ionized species (indicating galaxy and known X-ray source are the same)

THE OPTICAL SPECTRUM AND MORPHOLOGY OF THE PROBABLE X-RAY GALAXY NGC 5506(3U 1410 − 03)

A. S. Wilson.Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH

M. V. Penston, R. A. E. Fosbury.Anglo-Australian Observatory, PO Box 296, Epping, New South Wales, 2121,Australia

and

Royal Greenwich Observatory,Hailsham, Sussex BN27 1RP

and

A. Boksenberg.Department of Physics and Astronomy, University College, London

197 7T H E S UN’ S INT E N S E M AG NE T I C F IEL D

D. Galloway and company show that the magnetic fields can have an order of magnitude greater energy density than the kinetic energy.

Formation of intense magnetic fields near the surface of the Sun.D. J. Galloway, M. R. Proctor, N. O. Weiss,

Nature 266 (1977)

1978M 8 2 – T H E E XPLO D IN G GAL A X Y?

In a Nature paper, David Axon and Keith Taylor challenge the orthodox ‘explosion’ model to describe the Messier galaxy M82.

David Axon would later return to Sussex as Head of School of Mathematics and Physical Sciences up to his untimely death in 2012.

Axon and Taylor,Nature 274 37-38

1979M AG NE TIC BR AK IN G DU R IN G S TA R FO RM ATI O N – II

Part of series of papers on magnetic braking during star formation

J. Gillis. Weizmann Institute of Science, Rehovot, Israel.

L. Mestel. Astronomy Centre,University of Sussex, Falmer,Brighton, Sussex BN1 9QH.

R.B. Paris. Association Euratom-CEA, Centre d’Etudes Nucleaires, 92260 Fontenay-aux-Roses, France. Magnetic braking during star formation – II

Received 1978 August 7

Gillis, J, Mestel, L, Paris, RB. 1979MNRAS, 187,311

1980T H E C E N TAU RU S I C LU S T E R O F G AL A X I E S –AN E X TR E M E CA S E O F CONTA MINATI ON?

Evidence for the formation of dust in the mass-loss outflows from the emission line nuclei of planetary nebulae.

The Centaurus I galaxy cluster resolved into two distinct velocity systems.

Lucey, Dickens and Dawe 1980Nature.285...305L

C UMUL AT I V E NUM B ERS O F M S C G R ADUAT E S , 1967-2015

1981ABU NDA N C E S IN S TE LL AR P O PU L ATI O N S AND

T H E INT ERS T EL L AR M E D I UM IN G AL A X IE SI bet you’ve never written a paper that starts with “Like Ancient Gaul”!

Bernard Pagel 1930 - 2007 It is humbling (scary?) to see that many of the theme’s in Bernard and Mike’s review are still occupying astronomy today,e.g. abundance gradients and mass-metallicity relations

Pagel and Edmunds, 1981, ARAA, Vol19, 77P

1982FLO C C UL ENT AN D G R AN D - DE SI G N S P IR AL S TRUC TUR E

FRO M F IE LD TO G RO U P G AL A X IE S

A new classification for spiral arm structure and the finding that grand-design spiral structure is more than twice as frequent in bar-free spiral galaxies in pairs/groups, compared to isolated spiral galaxies.

Elmegreen, DM and Elmegreen, BG, MNRAS, 1982,201,1021

Type 2 Type 3Type 1

198 3TH E S TA B I L I T Y O F G E NER AL RE L ATI V I S TIC C O S M O LO G IC AL TH EORY

This important paper first demonstrated the stability of the standard de Sitter and Friedman solutions of general relativity.

Figure 1. The phase-plane portrait of the system (3.23) when K >0. Arrows denote the direction of increasing cosmic time. The critical point at [0,1) corresponds to the zero curvature, (o = 0), de Sitter space-time.

Barrow, JD, Ottewill, AC,1983JPhysA, 16,2757

1984INH O M O G E NEO U S C O S M O LO G IE S WI TH C O S M O LO G IC AL CONS TA NT

J. Barrow and J. Stein-Schabes

Asymptotically, the solutions we have found possess the same event horizon structure as the de Sitter space-time and are static in accord with the expectation of the ‘no hair’ conjecture.

Deviations from exact de Sitter space-time viewed by a geodesic observer decay exponentially in time within the observer’s event horizon.

Barrow and Stein-Schabes. Phys. Lett. A, 103, 315, 1984

198 5TH E E VO LU TI O N O F L ARG E - S CALE S TR U C T U RE IN

A U N I V E R S E D O M IN AT ED BY C O LD DA RK MAT TERThe definitive CDM work, ultimately wins the 2011 Gruber Cosmology Prize

The Evolution of Large-Scale Structure in a Universe Dominated by Cold Dark Matter.

Marc Davis, George Efstathiou,Carlos S Frenk, and Simon DMWhite.

Received 1984 August 20;accepted 1984 November 30

Davies, M, Efstathiou, G, Frenk, CS, White, SDM. 1985.ApJ. 292.371D.

2056 Citations.

C I TATI O N S VS TI ME

1986TH E AN TH RO P IC PR INC IPLE

Is the Universe the way it is because we are here to observe it?

1987N O N - G AU S S I AN S TATI S TIC S AND

TH E M IC ROWAV E BAC KG RO U ND R ADIATI ONOne of the earliest studies of the impact on non-Gaussianity on the CMB

Peter Coles and John D. Barrow

198 8EQUI V EL ANC E O F M OD IF I E D G R AV I T Y AN D S CAL AR FIEL DS

John Barrow and Spiros Cotsakis

John Barrow and Spiros Cotsakis (pictured right) showhow modified gravity theories of the f(R) variety can beexplicitly mapped into scalar field models, and appliedto inflation. Both were working at Sussex this year.

Inflation and the conformal structure of higher-order gravity theories, John D Barrow, Spiros Cotsakis,PLB Volume 214, Issue 4, 1 December 1988

1989M AG NE TIC F I E LD S IN COSMOLOGY

Mark Madsen writes an early article considering the still-unsolved problem of large-scale magnetic fields in the early universe.

Such primordial fields are a possible origin for the magnetic fields observed in galaxies and galaxy clusters, but there is no agreed formation mechanism in our current best early-universe models.

Above: Magnetic fields in the Milky Way.

Madsen, MNRAS (1989) 237 (1):109-117

1990E X T E N DE D INF L AT I O N ARY UNIV ERSE S

Inflationary models from general scalar-tensor gravity theories

Barrow, J, Maeda,K 1990Nuclear Physics B, 341,294

C I TAT ION S

1991A LO G N O RM AL M O DE L FO R TH E C O S M O LO G IC AL M A S S D I S TR IBU TI ON

Very widely-used model of the distribution of matter in the Universe

Coles and Jones 1991. MNRAS. 248.1C

1992S IM U L ATI N G TH E FO RM ATI ON O F A C LU S TE R O F G AL A X IE S

Peter was one of the pioneers of numerical techniques that reproduce complex astrophysics on cosmological scales. Sussex has remained at the forefront of the field of numerical astrophysics for over 20 years.

Thomas, P. and Couchman, H.,1992,MNRAS, 257,11T

1993TH E R AND O M M AG NE TIC F I E LD IN TH E GAL A X Y

Rotation measure study showing that the Milky Way’s magnetic field is ~5 µG and nearly in energy equipartition with the turbulent, thermal and cosmic ray energy density of the ISM.

Ohno, H and Shibata,S,MNRAS, 1993, 262, 953

1994FA L S E VAC U U M INFL AT I O N WI T H EI N S T EI N GR AV I T Y

The early nineties saw a number of important papers on inflation originating from Sussex.

This paper, which introduced the idea of a scalar field trapped in a false vacuum state, was particularly well received.

Copeland, Edmund J; Liddle, Andrew R; Lyth,David H; Stewart, Ewan D;Wands, David; 1994 PhysRevD, 49,6410

1995C O S M IC STR INGS

Hindmarsh and Kibble

Could dark matter be ‘topological defects’ that may have formed at phase transitions in the very early Universe?

If we can find cosmic strings then we will have a uniquely direct connection to the highly energetic events of the early Universe!

Cosmic Strings: Hindmarsh and Kibble 1995, Reports on Progress in Physics, 58,477

Sir Tom Kibble (1932-2016)

1996DE N S I T Y PE R T U RBATI O N S AN D BL AC K H O LE FO RM ATI O N IN HYBR ID

INFL ATI ONGarcía-Bellido, Juan

Two inflationary stages can trigger the formation of a large number of inflating topological defects.

Certain values of parameters these primordial black holes may constitute the dark matter in the Universe.

Some models postinflationary reheating occurs via black hole evaporation.

García-Bellido, Juan; Linde, Andrei;Wands,David 1996 PhRvD. 54.6040G

1997PRIM O RD I AL BL AC K H O LE C O N S TR A IN T S IN COSMOLOG IE S

W IT H E ARLY M AT T E R DOM INAT IONHow do primordial black holes change the matter power spectrum?

1997 PhRvD. 56.7559G

1998A S S I S TE D INFL ATI ON

(how to get near scale invariance using multiple fields)

In inflationary scenarios with more than one scalar field, inflation may proceed even if each of the individual fields hasa

potential too steep for that field to sustain inflation on itsown.

We show that scalar fields with exponential potentialsevolve

so as to act cooperatively to assistinflation.

Andrew R. Liddle, Anupam Mazumdar and Franz E. Schunck.

1999DA RK E NE RGY I S JU S T INFL AT ION

Andrew Liddle applies the scalar field dynamics of inflation to dark energy.

Our results indicate that exact solutions for the scalar filed, which give scaling behaviour when the expansion of the universe is driven by a dominant component with density dominant, are possible for only three classes of potentials:

1.Exponential potentials ( scales as dominant)

2. Negative power-law potentials( decreases less rapidly than dominant)

3. Positive power-law potentials( decreases more rapidly than dominant)

A Classification of scalar field potentials with cosmological scaling solutions.A Liddle and R Scherrer: Phys. Rev. D59 (1999)023509

Andrew Liddle applies the scalar field dynamics of inflation to dark energy, classifying all exact scaling solutions for quintessence models.

This work attracted ~500 citations.

2000S U PE R S TR IN G C O S M O LO GY RE V IE W

Sussex cosmologist Edmund Copeland and previous Astronomy Centre members James Lidsey and David Wands publish an influential review of the exciting field of early-universe cosmology in string theory.

In string theory, properties of our universe may depend on the geometry of complex mathematical spaces called Calabi-Yau manifolds

Lidsey et al Phys. Rept. 337 (2000)343-492

2001TH E E FFEC T O F R AD I ATI V E C O O L IN G O N S CAL IN G L AW S

O F X - R AY G ROUP S AN D CLUS TERSThere were 6 papers on cosmological simulations published this year at Sussex.

This one was the first to begin to investigate the physical reasons for departure from self-similarity.

Muanwong, O; Thomas, PA; Kay, ST; Pearce, FR; Couchman, HMP. 2001, ApJ, 552, 27

2001C O M PO S I T E Q UA SAR S PEC T R A FRO M T H E S LOAN D I G I TA L S K Y SURVE Y

QSO spectra from SDSS

~1000 citationsVanden Berg, DE et al 2001 AJ, 122, 549

2002IN C LUD IN G S TA R FO RM AT I O N AN D S U PE RN OVA FE ED BAC K WITH IN

C O S M O LO G IC AL S IM U L ATI O N S O F G AL A X Y FORMATI ON

Simulations can match observed luminosity functions by including feedback effects from star formation and supernovae

Kay et al. 2002. MNRAS. 330.113K

2003T H E F IR S T DATA RE LE A S E O F T H E S LOAN D I G I TA L S K Y SURVE Y

SDSS fundamentally changed the way we do astronomy

Alfred P. Sloan started off in toilets and ended up solving the mysteries of the Universe

Abazajian et al (including Jon Loveday),2003 A. 126. 2081A

2004[O I I I ] / [N I I ] A S AN AB U N DA N C E IN D I CAT O R AT H I G H RED SH IF T

Gas-phase metallicities are notoriously difficult to measure, especially in distant galaxies.

This paper discussed the utility of both the NII and the OIII indicator for metallicity measurements at high redshift.

Pettini, M and Pagel,BEJ,MNRAS, 2004, 348, 59

2005WH AT I S NE ED ED O F A TAC H YO N I F I T I S TO B E T H E DA RK ENERGY ?

Sussex continued to break ground in theoretical cosmology.

This ground-breaking paper introduced the idea that dark energy might be a transient phenomenon caused by the presence of a faster-than-light tachyon field.

Copeland, Edmund J; Garousi, Mohammad R; Sami, M; Tsujikawa, Shinji;2005, Phys. Rev. D 71, 043003

C O NC EP T S ( TO P 10 0 PA PERS)

2006T H E XM M C LU S T E R S U RV E Y: A M A S S I V E G AL A X Y C LU S T E R AT Z= 1 .45

S. Stanford

S. Stanford, Romer, AK et al,2006, ApJL, 646, 13S

2007INFO RM ATI O N C R I TE R I A FO R A S TR O PH YS IC AL M O DE L SELEC TI ON

The information theory and Bayesian approaches give significantly different conclusions from WMAP 3 data.

Liddle, A 2007, MNRAS. 377L. 74L

Bayesian Information Criterion (BIC)? Akaike Information Criterion (AIC)?Deviance Information Criterion (DIC)?

2008THE EFFEC T OF DWA RF GAL A X Y D ISRUP T ION IN SEMI - ANALY T ICAL MODEL S

Disruption during gravitational interactions suppresses the number of dwarf galaxies.

2008MNRAS. 383.1649H

2009L AUNC H O F PL ANC K AN D HERS CHEL

201 0A SY M M E T R I C B E AM S B E AT AN E XO T I C 9 S I G M A C M B ANOMALY

IN TO T H E DUST

Hanson, Lewis and Challinor,PRD

AU TH O R NE T WO RKS ( TO P 1 5 3 PA PERS)

201 1G AM A S U RV E Y C O RE DATA RELE ASE

Merging galaxies identified by GAMADriver et al. MNRAS (2011) 413 (2):971-995

The Anglo-Australian telescope where the survey was carried out

201 2T H E H ERS C H EL MU LT I - T I ER E D E X T R AG AL AC T I C S UR V E Y: HER MES

The HerMES survey

The HerMES survey Oliver, S.J. et al2012, MNRAS, 424,1614

201 3T H E H ALO M A S S FU N C T I O N T H RO U G H T H E C O S M I C AG ES

The halo mass function through the cosmic ages

How does the dark matter halo mass function evolves with redshift?

Watson et al. 2013.MNRAS. 433.1230W

201 4PL AN C K 201 3 RE S U LT S . X V I. C O S M O LO G IC AL PA R AME TE RS

It’s cosmology Jim, and just as we expected…

4435 citations so far!

Planck Collaboration (including Antony Lewis), 2014A&. 571A

201 5G AL A X Y FO RM ATI O N IN TH E PL AN C K COSMOLOGY

A new semi-analytical model of galaxy formation provides a good description of the build-up of stellar mass in passive and star-forming galaxies across ~12 Gyr of look-back time.

Henriques, B, White, S, Thomas, P et al.MNRAS, 2015, 451, 2663

2016H E LP : S TA R FO RM ATI O N A S FU N C TI O N OF G AL A X Y EN V IRO NM ENT WI T H HERS CHEL

Duivenvoorden, S, Oliver, S etal; 2016 MNRAS,462,277

The Herschel Extragalactic Legacy Project (HELP) brings together a vast range of data from manyastronomical observatories to investigate the environmental dependence of star formation.

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A S TR O N O M Y C ENTR ED EPA R TM ENT O F P H Y SIC S A N D A S TR O N O M Y

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