Martin White and collaborators have submitted for publication one of the first SDSS-III BOSS science papers. The paper entitled “The clustering of massive galaxies at z~0.5 from the first semester of BOSS data” uses some of the first data ever taken for BOSS last year to look at how the galaxies they are selecting populate the underlying “dark matter halos” that we believe enshroud all galaxies and clusters of galaxies. Using the first measurements of the clustering of BOSS galaxies, compared to detailed simulations of the BOSS survey, White et al. were able to show that 90% of BOSS galaxies were preferentially located to at the centers of their dark matter halos and thus excellent tracers of those halos . This is one of the main assumptions of BOSS and therefore re-assuring to check! There is still a long way to go, but it is good to see BOSS producing results. The full paper is available on the arXiv preprint server but we provide below a snapshot of the title, authors and abstract. Enjoy.
Author: bsouter
Photos from Paris Collaboration Meeting
We all had fun at the Paris SDSS-III collaboration meeting and provide here a selection of photos.
APOGEE gets a camera!
The APOGEE spectrograph is coming together with the last of the optics installed early October. The camera optics and mechanics were designed and integrated by New England Optical Systems (NEOS). It features four pure silicon and a pair of fused silica lenses with the largest lens approximately 400 millimetres. It was installed along side of the VPH grating which itself is the largest mosaic grating of its kind. After installation, the optics will be warm aligned and tested. The first “cool-down” of APOGEE is less than two weeks away!
(Photos from Fred Hearty. Thanks!)
SDSS in Prague?
No, not a location suggestion for the next SDSS-III collaboration meeting but an observation by SDSS-III scientist Eyal Kazin (NYU) who was shocked to encounter the SDSS at the Stefanik Observatory on a recent trip to visit friends. He writes:
They display astronomy in general, and cosmology in particular, and I was very happy to see that SDSS is recognized in association with galaxy mapping. I just wanted to share with you the photo I took. You can see the 2.5m telescope, as well as a pie chart created, I believe, by Michael Blanton, as well as the Sloan-Great wall.
We’ll always have Paris
Blog by David Weinberg (SDSS-III Project Scientist)
One-hundred and thirty scientists from four continents gathered in Paris for the second annual meeting of the SDSS-III collaboration, hosted by the laboratoire AstroParticule et Cosmologie (APC).
Paris 2010 continues a tradition that began in 1994, with the first SDSS collaboration meeting at Yerkes Observatory. Early collaboration meetings were filled with discussions of hardware, data pipelines, target selection, and survey strategy. Over the years, as the SDSS steadily accumulated the largest data sets in the history of astronomy, the proceedings shifted more and more towards scientific discoveries, about the large scale structure of the universe, the evolution of galaxies and quasars, the history of the Milky Way, the physics of stars, and the genealogy of asteroid families (see the highlights summaryat sdss.org). The sequence of SDSS-I and SDSS-II collaboration meetings culminated in 2008 with an international symposium that celebrated the scientific achievements and influence of the SDSS.
SDSS-III involves four new surveys, two new instruments, major upgrades to the original SDSS spectrographs and the fiber system that supports them, and many new participating institutions and scientists. The first SDSS-III collaboration meeting (Princeton, 2009) was in many ways a return to the early days, focused again on hardware, software, survey strategy, and organization of science teams.
One year along, Paris 2010 shows a project in transition, or, more precisely, four projects at four different transitions. Talks about nearly complete analyses of the chemistry and kinematics of the Galactic disks in SEGUE-2 and the aridity of the brown dwarf desert in MARVELS alternated with talks describing first measurements from the BOSS galaxy and Lyman-alpha forest surveys and the rapid progress of the APOGEE infrared spectrograph toward its commissioning in early 2011. After a day and a half of plenary sessions, the meeting split into another day and half of survey-specific parallel sessions, where team members dug into details of the science analyses, reviews of target selection efficiency, theoretical predictions and mock catalogs, and the nitty-gritty of signal-to-noise thresholds, sky coverage, and plate scheduling algorithms.
While the days started early and ran late, everyone also took the opportunity to enjoy the delights of Paris, guided expertly by LOC Chair Eric Aubourg. Highlights included the conference dinner cruise along the Seine and “wine lover’s lunches” at a small restaurant near the APC. It was asserted more than once that attending a wine lover’s lunch would improve one’s afternoon talk. This attractive hypothesis was not rigorously tested, though anecdotal evidence did not prove it obviously false.
Twenty years after the SDSS was conceived, it remains an exciting project at the cutting edge of observational astronomy, and it continues to demand the efforts, talents, and insights of a large collaboration. The collaboration meetings are intense, and they are fun.
Plus ca change, plus c’est la meme chose.
APOGEE takes shape
The last of the sdss3 instruments is making rapid progress and will soon be on the sky. Photographs below from Fred Hearty at the University of Virginia (UVa) show the delivery of the cryostat at UVa during July. The 4,000 pound instrument was manufactured by Basil Blank at PulseRay in Beaver Dams NY and just barely fit in the truck and the UVa labs.
The two images below show the spectrograph components being integrated into the cryostat. The VPH grating in its mount is in the background as it was being positioned, as well as the Fold 1 Mirror and Collimator (left and right foreground respectively). A close-up of the VPH – only large format mosaic VPH in the world – is shown in a closeup. The final two optics (Fold 2 and Camera) are fabricated and will be installed next week (Sept 2010). The detector array, which is in safe keeping at UVa, will be installed after the first thermal cycle of all major optics.
Read all about it!
Ann Finkbeiner has now written the history of the original Sloan Digital Sky Survey, with a nod to SDSS-II and SDSS-III. The publication date is August 17 2010, and can be found at a number of booksellers .
Below is the cover of the SDSS book A Grand and Bold Thing .
New SDSS-III website
The new SDSS-III website has been launched. This includes up-to-date information on the surveys, data releases and instrumentation (including photos), all the important SDSS-III collaboration documents (publication policy, PoO and the external collaborators policy) and updates and links to the SDSS-III blog and press releases.
BOSS finishes 200 plates!
The SDSS-III BOSS project has completed 202 survey-quality plates, which translates to 200,000 spectra already taken by this survey. The survey is now shutting down for the summer to perform essential maintenance, but will be back on the sky in the Fall for several more years. The goal is to obtain approximately 1.5 million galaxies and quasars over the whole sky accessible to Apache Point Observatory.
We provide here a first look at these new data as a “pie-diagram” which shows their distribution on the sky relative to previous SDSS data. In red, we show the new BOSS Luminous Red Galaxies (LRGs) that probe to a high redshift (greater distance) than the previous SDSS LRGs (shown in white) and the normal (MAIN) SDSS galaxies in yellow. As can be seen, BOSS will probe a much greater volume of the universe than these previous surveys.
We also show below the BOSS quasars in blue, which now probe an enormous volume of the Universe!
Diagrams courtesy of Michael Blanton (NYU)
SDSS3 collaboration visits Pittsburgh
Thirty members of the BOSS Lyman-alpha Forest and Quasar Working Groups met for a workshop in Pittsburgh from Jun 21-24 , hosted by the McWilliams Center for Cosmology at Carnegie Mellon University.
The Working Groups comprise those survey members most interested in high redshift quasars and the intergalactic medium. The quasar spectra collected by the survey act as backlights, illuminating the intergalactic gas. This gas causes absorption features in the spectra (mostly the hydrogen Lyman-alpha “forest”) and by analyzing the spectra we can measure the large scale structure of intergalactic material. The prime aim of the survey is to see this structure on scales many times larger than any previous Lyman-alpha forest survey, and use the presence of the baryon oscillation feature to constrain dark energy.
The accumulation of this vast new dataset, will make many other science projects be possible, from measurements of faint quasar black hole clustering to the searches for faint traces of rare chemical elements in intergalactic space. The Pittsburgh meeting was partly dedicated to exploring these different possibilities.
BOSS Survey Scientist Kyle Dawson started the meeting off with a summary of what has been a successful first year of survey operations. There are nearly as many quasar spectra in the interesting redshift range to analyze than all previous surveys put together, and there are still 5 years of data to come.
Questions of survey strategy came up, and in particular how the signal to noise reached so far in spectra will translate into cosmological constraints. Here David Weinberg leads a discussion on how well the survey is doing.
Preliminary results from first year data were presented in many of the talks. Here Jordi Miralda-Escude reports on measurements of large-scale structure in the intergalactic medium made by the survey.
Members of the French Participation Group were heavily represented. Their team is examining every single of the tens of thousands of quasar target spectra by eye. Christophe Yeche and Isabelle Paris seen here with conference co-organizer Nic Ross show that they must be enjoying it.
Whether the SDSS3 logo looks better on an ipad was also an interesting issue for some people.
With 30 talks and working group sessions spread over 4 days, it was useful to be able continue serious discussion at a Pittsburgh landmark, the Church Brew Works: