Lorentz Center - The Dynamic Nature of Baryons in Halos from 6 Aug 2012 through 10 Aug 2012
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    The Dynamic Nature of Baryons in Halos
    from 6 Aug 2012 through 10 Aug 2012


Scientific report

Baryons, the `normal’ matter that makes up the periodic table of elements, are the fuel for the formation of stars and galaxies, and thus create the visible Universe. Over time, baryons flow into ‘halos’, gravitational overdensities that seed the formation of galaxies, and build up the galaxy population we see around us. Some fraction of this material is subsequently ejected through complex and energetic stellar evolution processes, regulating the growth, and shaping the properties, of galaxies. An understanding of the dynamic nature of halo baryons is therefore a critical ingredient in a complete theory of galaxy formation, and was the focus of our workshop.

The majority of baryons, however, reside outside of galaxies in a diffuse phase. Their detection and characterisation requires observations spanning the energy spectrum from radio wavelengths to Xrays. A key innovation of our workshop was to assemble a team of leading observational astronomers from these complementary, but often disconnected, observational disciplines, in concert with astrophysicists specialising in hydrodynamical simulations of galaxy formation, to build a holistic picture of baryon evolution.

In total, 47 scientists from around the globe participated, contributing to our themes ‘An introduction to halo baryons’, ‘Observational probes of halo baryons’, ‘Physical processes driving baryon dynamics’, ‘Identifying future challenges and opportunities’, and ‘Scientific synthesis’. Discussionoriented scheduling, encouraged by the Lorentz Center, was central to fostering the vigorous discussion between disciplines, particularly following reviews for each theme, from researchers targeted by the SOC. This defining feature of our workshop built strong awareness of synergies between disciplines and fostered new lines of enquiry that have already yielded publications in high impact journals.

Moreover, the SOC’s aim to involve the researchers that represent the future of the field was a notable success. Discussions led by early career researchers were an important element of the programme, and able candidates to lead them were targeted by the SOC ahead of the meeting and asked to prepare points for debate. Following the success of one such session, the discussion leader has been offered an invited review at a major international conference.

Feedback from delegates was overwhelmingly positive, particularly in respect of the collaborative environment fostered by the Lorentz Center. We currently plan to hold a follow up workshop, with a very similar format, in late 2013 or early 2014, most likely in Australia.


The SOC are indebted to Ikram Cakir, Mieke Schutte and Henriette Jensenius at the Lorentz Center for their expert advice, enthusiasm and professionalism, without which the workshop could not have been a success.


Scientific organizers:

Joel Bregman (University of Michigan, USA)

James Bullock (University of California, USA)

Robert Crain (Leiden Observatory, Netherlands)

Benjamin Oppenheimer (Leiden Observatory, Netherlands)

Mary Putman (Columbia University, USA)

Jason Tumlinson (Space Telescope Science Institute, USA)