Luis Campusano, Dpt Astronom í a , Universidad de Chile
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Transcript of Luis Campusano, Dpt Astronom í a , Universidad de Chile
Reu Sochias:14-16 Enero 2009
Luis Campusano, Dpt Astronomía, Universidad de Chile
Large Quasar Groups as Large Quasar Groups as Signposts of the galaxy Large Signposts of the galaxy Large
Scale Structure at z>0.5Scale Structure at z>0.5
Reu Sochias:14-16 Enero 2009
Collaborators
Roger Clowes, KA Harris (U Central Lancashire, UK)
Gerry Williger Lutz Haberzett JT Lauroesch (U Louisville, USA)
R Davé (U Arizona), MJ Graham (Caltech), AM Koekemoer (STScI)
Chris Haines (U Birminghan, UK), J Loveday (U Sussex), I Sochting (Oxford)
andD. Valls-Gabaud (Observatoire de Paris, France).
Reu Sochias:14-16 Enero 2009
Galaxy LSS: the 2dF redshift survey (Figure credit: W.
Schaap,U Groningen)
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Sponge like topology and Walls in galaxy
distribution (z<0.3)
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BIG QUESTIONS
NOTICE THAT GALAXY FORMATION IS NOT YET A SOLVED PROBLEM
IS THERE INDEED A HOMOGENEITY SCALE IN THE UNIVERSE? (POSSIBILITY OF A FRACTAL STRUCTURE)WHAT ARE THE DETAILS OF THE ‘LOCAL’ LARGE SCALE STRUCTURES?
FILAMENTS AND WAALS ALREADY IN PLACE AT HIGH REDSHIFTS?
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Galaxy LSS (2dF,SDSS,6dFS)
Sheet-like LSS as the “Great Wall” of galaxies (Geller & Huchra 1989) are typical phenomena.
Waals with average extent of 50-100 Mpc, comprising ~50% of the galaxiesLow density regions or VOIDS ~50 Mpc in size
The underdense regions are criss-crossed by FILAMENTS having a variety of richnesses
Reu Sochias:14-16 Enero 2009
Standard LCDM predictions
Predicts weak non-linear structures at low-z of the dimensions of waalsSimulations indicate Great-Wall like sheets become rare at z~1 (Evrad et al. 2002)
Current extended redshift surveys do reach only to z~0.2-0.3. Direct observations of ‘Great-Waals’ at z~1 would provide a strong test for theory
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Grid Structures in numerical simulations:
LCDM evolution
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Large Quasar Groups
The largest structures seen so far in the early universe (z~0.4-2.0)
With sizes in the range 70-250 Mpc, and membership ~5-20
Several of them have been followed-up, including searches of correlated galaxy distributions
Reu Sochias:14-16 Enero 2009
Large Quasars Groups
Quasars may signal gas-rich mergers environments
Large Quasar Groups (LQGs) are potentially unique structure markers on scales up to hundreds of MpcLQGs allow the discovery of huge structures, and potentially allow the study of their quasars and galaxies in a wide variety of environments, from low to high densitiesLQGs may signal huge structures to z~3 and test if there are high-z Great-Waals
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Large Quasar Groups
LQGs can contribute to constrain the various physical mechanisms (feedback, merger, etc) which produce the quasars
LQG space density is 7 Gpc-3 at 0.3<z<1.9 (Pilipenko 2007)
Implies LGQs are large perturbations, with 500-1000 LQGs on 100-200 Mpc scales at z<2.8 (Pilipenko 2007)
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Clowes-Campusano LQG
At z~1.3 with a longest dimension of ~250 Mpc
Several follow-up investigations have been done, revealing accompanying overdensities of galaxies in these LQGsIn addition to the galaxy distribution, several clusters of galaxies have been found to be embeded in the LQGs
After follow-up, a second LQG was discovered in the same direction at z~0.8
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Conclusions
Large Quasar Groups can trace mass to at least z~2 and thus are powerful tools to study galaxy evolution and structure formation at high redshiftToday’s quasar surveys over extended areas of the sky allow searches of LQGsLQGs are a tool to search for super-large structures to z>=2 and to further test the hypothesis of homogeneity of the UniverseTheoretical models predict ‘Grear Waals” of >500 Mpc in size. LQGs may find an upper z-limit for the existence of “Great Waals’.
Reu Sochias:14-16 Enero 2009 FINFIN