IoA Theoretical and X-ray Astronomy consolidation

Lead Research Organisation: University of Cambridge
Department Name: Institute of Astronomy


This proposal is for an interim grant to support research in Theoretical Astrophysics and X-ray Astronomy at the Institute of Astronomy (IoA), as part of a transition to a fully consolidated IoA Astronomy grant proposal in 2012.

The Theory theme addresses a wide range of astrophysical phenomena ranging from the origin of the Universe itself to the formation and evolution of galaxies, stars and planets. One of the main areas of investigation is cosmology. Members of the IoA are playing a leading role in the European Space Agency Planck mission, and will lead a definitive determination of the cosmological parameters including the age, size, dark matter, dark energy and baryonic contents of the Universe. Another project will carry out theoretical simulations and analysis of the subsequent evolution of cosmic structure during the epoch of reionisation, when the first stars and galaxies were formed.

Star formation is another major focus of the grant, on scales ranging from galaxies, where the molecular clouds giving birth to stars are formed, to the formation of stars and star clusters within these molecular clouds. These investigations will combine state-of-the-art numerical simulations with analytical theory and a rich new set of multi-wavelength observations of nearby galaxies being obtained with the Herschel and Spitzer space observatories under IoA leadership.

The understanding of planetary systems around stars and their formation is another goal of the Theory theme. One project will focus on modelling the properties of debris discs, discs of asteroids, cometary objects, and dust surrounding stars, using a complete IoA-led survey of nearby stars with the Herschel observatory (DEBRIS project). Another project is directed at modelling the evolution of the planetary orbits themselves in different stellar environments and stellar evolutionary stages.

The final component of the Theoretical Astronomy theme is the modelling of binary star systems, and improving our understanding of how double star systems evolve when the component stars are immersed in a common envelope. This phase of evolution is important for understanding a wide range of observed stellar systems including cataclysmic variables, X-ray binaries, and the progenitors of supernovae, including the Type Ia supernovae which are used as cosmological standard candles.

The second theme of the proposal is X-ray Astronomy. The research will exploit a large body of observations of galaxies, galaxy clusters, and Galactic X-ray binary systems being obtained by the X-ray group on the Chandra, XMM-Newton, Suzaku and ASTRO-H X-ray observatories to carry out three projects.

One project will carry out measurements of the spin of black holes, both the supermassive black holes which power the enormous energy emissions from quasars and other active galactic nuclei, and the stellar-mass black holes in binary star systems. This work, based on spectroscopy of relativistically-broadened iron lines, will also provide insights into the accretion phenomena that power the systems.

Another project will combine deep X-ray imaging and spectroscopy of the cores of galaxy clusters to study the physical conditions, turbulence, and acoustic waves and shocks in the intracluster medium, and constrain the physical nature of the feedback of radiative and mechanical energy from the galaxies in the cores of the cluster and the surrounding intergalactic gas in the clusters.

A related project will combine these X-ray data with multi-wavelength measurements of the intergalactic filaments and other gas components in the clusters, to understand the feedback processes linking cooling of intergalactic gas into the central galaxies and the subsequent heating of the surroundings by the central galaxies and their embedded black holes.

Planned Impact

The main societal impacts of this research are in the areas of public engagement and inspiration of future young scientists. Many of the proposed projects are coupled to high-profile missions and investigations,
which will impact the public through press and image releases, public lectures, interviews with the print, radio, and television media, popular articles and books, and formally organised outreach activities.

Projects which are sure to produce high-impact science in the public area include the announcement of first full results on cosmological parameters from the ESA Planck mission in early 2013, work on deep X-ray imaging and spectroscopy of clusters with the XMM-Newton and Chandra missions, and the interpretations of data from the Herschel Space Observatory on star formation in galaxies and debris discs. The Co-Applicants and their collaborators have established a heritage of high-visibility results in these and related areas, and will coordinate closely with media and outreach offices of the STFC, ESA, and relevant mission offices.

The Institute of Astronomy fully embraces the outreach agenda of the STFC, and the research activities in the Theoretical Astronomy and X-ray Astronomy themes form core components feeding these activities. Impacts will arise from a combination of IoA-organised efforts and individual activities by the Co-Applicants and PDRAs.

The wide range of outreach activity is made possible by the critical mass of astronomy activity at IoA and through contributions from our major research grants and from Departmental resources. These include weekly public evening lectures and (weather permitting) observing sessions in the winter which attract more than 1500 people per year, an annual open day which attracts comparable numbers in a single afternoon and evening, one-day schools workshops, on-line newsletters, podcasts, and an informal website, and an Artist-in-Residence programme.

Virtually every Co-Applicant and PDRA also undertakes public engagement and outreach activities individually, and many (e.g., Crawford, Efstathiou, Fabian, Kennicutt, Rees) have engaged in scores of activities over the past five years, via named and national public lectures, speaking at national amateur astronomy meetings and festivals, radio and television interviews and programmes, and by writing popular articles and books. Worth of special mention is the recent work by Fabian with the STFC in developing a booklet "A New View of the Universe: Big Science for a Big Society" which presents the scientific and Council objectives for astronomy in the coming decade, and documents the many broader economic and societal impacts of astronomy, ranging from technology transfer (e.g., WIFI, GPS, detectors, adaptive optics) to major societal priorities (e.g., climate change, energy sustainability). Co-Applicant C. Crawford, in addition to leading the IoA outreach programme, is an active spokesperson for astronomy in her own right, and in 2009 was received a UKRC Woman of Outstanding Achievement award in recognition of her work in fostering engagement between scientists and the public. Last but hardly least Co-Applicant and Astronomer Royal M. Rees continues to serve as one of the UK's leaders in the scientific community, and has engaged with the public on countless occasions through books and popular articles, public lectures, and most recently through is service as President of the Royal Society.

The effectiveness of this collection of activities owes much of its success to the work of the IoA Outreach Officer, Co-Applicant Carolin Crawford. This work is supported by an 0.5 FTE appointment, and this proposal requests funding for 40% of this work (0.2 FTE), which we estimate represents the fraction of activities relating to the work of the Applicants and PDRAs on this grant.


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