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sub-millimetre galaxies
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Title: On the nature of sub-millimetre galaxies
Authors: James S. Dunlop

I discuss our current understanding of the nature of high-redshift (z > 2) (sub)-millimetre-selected galaxies, with a particular focus on whether their properties are representative of, or dramatically different from those displayed by the general star-forming galaxy population at these epochs. As a specific case study, I present some new results on the one sub-millimetre galaxy which happens to lie within the Hubble Ultra Deep Field and thus benefits from the very best available ultra-deep optical-infrared Hubble Space Telescope and Spitzer Space Telescope imaging. I then consider what these and other recent results from optical-infrared studies of sub-millimetre and millimetre selected galaxies imply about their typical masses, sizes and specific star-formation rates, and how these compare with those of other star-forming galaxies selected at similar redshifts. I conclude with a brief discussion of the continued importance and promise of SCUBA2 in the era of Herschel.

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RE: SCUBA Galaxies
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Title: The SCUBA HAlf Degree Extragalactic Survey (SHADES) -- VI. 350 micron mapping of submillimetre galaxies
Authors: Kristen Coppin (UBC, Durham), Mark Halpern (UBC), Douglas Scott (UBC), Colin Borys (Toronto), James Dunlop (Edinburgh), Loretta Dunne (Nottingham), Rob Ivison (Edinburgh, UK-ATC), Jeff Wagg (NRAO, INAOE), Itziar Aretxaga (INAOE), Elia Battistelli (UBC), Andrew Benson (Caltech), Andrew Blain (Caltech), Scott Chapman (Caltech), Dave Clements (Imperial), Simon Dye (Cardiff), Duncan Farrah (Cornell), David Hughes (INAOE), Tim Jenness (JAC), Eelco van Kampen (Innsbruck), Cedric Lacey (Durham), Angela Mortier (Edinburgh), Alexandra Pope (UBC), Robert Priddey (Hertfordshire), Stephen Serjeant (Open University), Ian Smail (Durham), Jason Stevens (Hertfordshire), Mattia Vaccari (Padova)

A follow-up survey using the Submillimetre High-Angular Resolution Camera (SHARC-II) at 350 microns has been carried out to map the regions around several 850 micron-selected sources from the Submillimetre HAlf Degree Extragalactic Survey (SHADES). These observations probe the infrared luminosities and hence star-formation rates in the largest existing, most robust sample of submillimetre galaxies (SMGs). We measure 350 micron flux densities for 24 850 micron sources, seven of which are detected at >2.5-sigma within a 10 arcsec search radius of the 850 micron positions. When results from the literature are included the total number of 350 micron flux density constraints of SHADES SMGs is 31, with 15 detections. We fit a modified blackbody to the far-infrared (FIR) photometry of each SMG, and confirm that typical SMGs are dust-rich (Mdust~9x10^8 Msun), luminous (Lfir~2x10^12 Lsun), star-forming galaxies with intrinsic dust temperatures of ~35 K and star-formation rates of ~400 Msun/yr. We have measured the temperature distribution of SMGs and find that the underlying distribution is slightly broader than implied by the error bars, and that most SMGs are at 28 K with a few hotter. We also place new constraints on the 350 micron source counts, N350(>25mJy)~200-500 deg^-2.

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Title: Weighing Black Holes in high-z SCUBA Galaxies
Authors: D.M. Alexander (Durham)
(revised v2)

Deep SCUBA surveys have uncovered a population of dust-enshrouded star-forming galaxies at z~2. Using the ultra-deep 2 Ms Chandra Deep Field-North survey we recently showed that a large fraction of these systems are also undergoing intense black-hole growth. Here we provide further constraints on the properties of the black holes in SCUBA galaxies using the virial black-hole mass estimator. We show that typical SCUBA galaxies are likely to host black holes with M_BH~10^7-10^8 M_solar which are accreting at, or close to, the Eddington limit. These results provide qualitative support for our earlier conclusion that the growth of the black hole lags that of the host galaxy in these massive ultraluminous galaxies.

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SCUBA Survey
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Title: The SCUBA Half Degree Extragalactic Survey (SHADES) -- II. Submillimetre maps, catalogue and number counts
Authors: K. Coppin, E.L. Chapin, A.M.J. Mortier, S.E. Scott, C. Borys, J.S. Dunlop, M. Halpern, D.H. Hughes, A. Pope, D. Scott, S. Serjeant, J. Wagg, D.M. Alexander, O. Almaini, I. Aretxaga, T. Babbedge, P.N. Best, A. Blain, S. Chapman, D.L. Clements, M. Crawford, L. Dunne, S.A. Eales, A.C. Edge, D. Farrah, E. Gaztanaga, W.K. Gear, G.L. Granato, T.R. Greve, M. Fox, R.J. Ivison, M.J. Jarvis, T. Jenness, C. Lacey, K. Lepage, R.G. Mann, G. Marsden, A. Martinez-Sansigre, S. Oliver, M.J. Page, J.A. Pea****, C.P. Pearson, W.J. Percival, R.S. Priddey, S. Rawlings, M. Rowan-Robinson, R.S. Savage, M. Seigar, K. Sekiguchi, L. Silva, C. Simpson, I. Smail, J.A. Stevens, T. Takagi, M. Vaccari, E. van Kampen, C.J. Willott

We present the maps, source catalogue and number counts of the largest, most complete and unbiased extragalactic submillimetre survey ever undertaken: the 850-micron SCUBA HAlf Degree Extragalactic Survey (SHADES). Using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), SHADES mapped two separate regions of sky: the Subaru/XMM-Newton Deep Field (SXDF) and the Lockman Hole East (LH). These SCUBA maps cover 720 square arcmin with an RMS noise level of about 2 mJy and have uncovered >100 submillimetre galaxies. In order to ensure the utmost robustness of the resulting source catalogue, data reduction was independently carried out by four sub-groups drawn within the SHADES team, providing an unprecedented degree of reliability with respect to other SCUBA catalogues available from the literature. Individual source lists from the four groups were combined to produce a robust 120-object SHADES catalogue; an invaluable resource for follow-up campaigns aiming to study the properties of a complete and consistent sample of submillimetre galaxies. We present differential and integral source number counts of submillimetre galaxies and find that the differential counts are better fit with a broken power-law or a Schechter function than with a single power-law; the SHADES data alone significantly show that a break is required at several mJy, although the precise position of the break is not well constrained. We also find that an 850-micron survey complete down to 2 mJy would resolve 20-30 per cent of the Far-IR background into point sources.

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SCUBA Galaxies
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A major breakthrough in pinpointing some of the most primordial and violently star forming galaxies in the Universe has been made by a joint collaboration of UK and US astronomers using the Spitzer Space Telescope to resolve primordial galaxies initially detected by the James Clerk Maxwell telescope (JCMT). UK astronomers from the University of Kent, The Royal Observatory Edinburgh and the University of Oxford teamed up with American cosmologists to finally identify these elusive galaxies. The work will be published in the Astrophysical Journal Supplement Spitzer Special Issue in September 2004.

Back in 1995, the UK's SCUBA camera (Sub-millimetre Common User Bolometer Array) on the James Clerk Maxwell Telescope in Hawaii, which detects light with wavelengths just under a millimetre, began finding fuzzy traces of very distant, primordial galaxies. Some of these are either too distant or too dusty to be seen even by the Hubble Space Telescope. But SCUBA's images on their own, and those of other similar cameras, are not fine enough: within the fuzzy SCUBA detections are sometimes many galaxies. So astronomers have spent enormous effort following up these SCUBA galaxies on other telescopes, particularly radio telescopes, to answer the question: which one is the primordial galaxy, and which ones are in the foreground? But even with the most sensitive radio telescope images ever made, only around half the SCUBA galaxies can be pinpointed unambiguously. Even worse, the radio telescopes miss all of the most distant and most primordial of SCUBA's galaxies.


This image show massive galaxies caught in the throes of formation. The stars are forming so rapidly that an entire galaxy can be built in a short timescale (cosmologically speaking, so a billion years or so). This star formation is thought to be driven by mergers of older galaxies in a filamentary structure spanning millions of light years. In billions of years time, this structure is predicted to become a cluster of giant elliptical galaxies similar to those we see today in the local Universe.

UK and US astronomers teamed up to combine Spitzer's sharp images with SCUBA's ability to find primordial galaxies. The team were stunned to find all the SCUBA galaxies in Spitzers field of view detected in only ten minutes with Spitzer. These breakthrough observations, described as a watershed by the team, finally give astronomers a way of unambiguously pinpointing even the most distant of SCUBA's galaxies. This could only be done by combining SCUBA with the Spitzer Space Telescope: SCUBA shows there is a primordial, violent starburst somewhere in the vicinity, which is then pinpointed by Spitzer.

At the same time, Spitzer solved another mystery about SCUBA galaxies. When Galileo first trained a telescope at the Milky Way, he was astonished to find the fuzzy light resolved into many individual stars. This is, in essence, what the team of astronomers have done with the diffuse extragalactic background light seen from all directions at a wavelength of about half a millimetre. By comparing the distinct Spitzer galaxies with the SCUBA data, the team discovered that they had identified the sources of this cosmic background for the first time. This background is caused by an important population of galaxies: most of the stars in the early Universe are created in these galaxies, and star formation is where everything comes from - including the material that makes planets like our own. Finding where this star formation happens tells us, in a sense, where we came from. Identifying most of these galaxies is a second coup for the joint UK/US team.



It is thought these distant galaxies in the early Universe will evolve into the most massive elliptical galaxies seen at the present day. These giant galaxies consist of 1000 billion stars like our Sun and are found in large groups or clusters.

"Our Spitzer Space Telescope images picked our galaxies out astonishingly quickly, in only ten minutes, when the community has been pouring effort into detecting them. This really is pioneering work and a great triumph for the Spitzer Space Telescope and the UKs SCUBA camera. To cap it all, at the same time weve found the galaxies that dominate the star formation in the early Universe. The Earth and everything on it is made from the dust created in stars like those people, trees, beef burgers, the lot." - Dr. Stephen Serjeant (University of Kent, UK).

"In 10 minutes, the Spitzer Space Telescope has managed to pinpoint the galaxies we have been chasing for 7 years. We can finally begin to sort the babies and teenagers of the galaxy world from the adults and senior citizens." - Dr. Rob Ivison (Royal Observatory Edinburgh, UK).

"These Spitzer observations were designed as the first joint survey using the MIPS and IRAC instruments on Spitzer, to assess the instrument sensitivities. As a matter of fact, it's a great technological, operational and scientific success, overwhelming our wildest expectations. This demonstrates the amazing capabilities of Spitzer for studying galaxy evolution at high redshifts; no doubt that deeper and larger ongoing surveys will give even more exciting results!" - Dr. Herv Dole (University of Arizona USA and IAS, Orsay, France).

"We expected to detect one or a few of these galaxies, but I was stunned that we detected all of the ones we looked at. The new data finally tell us what these galaxies are all about. We've known all along that they had to be far away and rapidly turning all their gas into stars, but now we know their true distances and ages." - Dr. Steve Willner (Harvard-Smithsonian Centre for Astrophysics, USA).

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