1 / 13

Binary Quasars in the Sloan Digital Sky Survey

Binary Quasars in the Sloan Digital Sky Survey. Joseph F. Hennawi Berkeley. Hubble Symposium April 7, 2005. Suspects. Naohisa Inada (Tokyo). Gordon Richards (Princeton). Masamune Oguri (Princeton). Michael Strauss (Princeton). Conclusions.

fabiana-fullam
Télécharger la présentation

Binary Quasars in the Sloan Digital Sky Survey

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Binary Quasars in the Sloan Digital Sky Survey Joseph F. Hennawi Berkeley Hubble Symposium April 7, 2005

  2. Suspects Naohisa Inada (Tokyo) Gordon Richards (Princeton) Masamune Oguri (Princeton) Michael Strauss (Princeton)

  3. Conclusions • New sample of 26 binary quasars with separations R < 50 kpc/h more than doubles the number known • First measurement of quasar clustering on small scales 10 kpc/h < R < 400 kpc/h (proper) • The quasar correlation function gets progressively steeper on sub-Mpc scales • Factor of 10-30 excess clustering is detected on scales < 40 kpc/h over extrapolation of large scale power law • Is excess clustering the hallmark of mergers and dissipative interactions which trigger quasar activity in rich environments?

  4. Djorgovski realized that 3 close pairs in sample ~ 3000, implies a pair probability P(R< 200 kpc/h) ~ 10-3 An Old Problem: Excess Close Pairs • Binary Quasar Lore • tides/mergers galaxy activated • large R ~ 100 kpc/h no tides • small R ~ 10 kpc/h tDF < tH P(<R) Probability of Having a Companion • Could these be strong lenses? • No corresponding radio population • Requires dark/exotic mass concentration • “We don’t expect splittings this large . . . .” R [kpc/h] Comoving Transverse Separation Djorgovski (1991)

  5. Fiber Collisions: Optical fibers can only be packed so tightly For 2dF: No pairs with  < 35” For SDSS: No pairs with  < 55” Shot Noise Volume decreases faster than the correlation function increases Small Scale Quasar Clustering Proper Mpc/h 4 10 40 0.4 1 2dF: Croom et al. (2005) n = 35 deg-2 Solutions 1. Wait for next generation all sky (i < 21) spectroscopic survey of ~ 106 quasars • Several years of observing • Need $$ + huge consortium of people 2. Target only ~ 200 close pairs (i < 21) • Use LF to get mean density • Less than 20 nights of observing • Sucker in one graduate student Comoving Mpc/h

  6. ARC 3.5m SDSS 2.5m Jim Gunn Why Observe at Princeton? • SDSS spectroscopic survey • 4000 deg2 • 45,000 low -z quasars i < 19.1 • 5,000 z > 3 quasars i < 20.2 • Precise 5 band (u,g,r, i, z) photometry • ARC 3.5m telescope • Plenty of time available in a department full of theorists • Remote operation from comfort of basement of Peyton Hall • There was little else to do at night in Princeton Apache Point Observatory (APO)

  7.  = 14.7” UVX low-z qsos 55” 3.3 3.0 3.5 4.0 A-stars WD Excluded Area 4.5 5.0 Keck Spectrum taken by Bob Becker & Michael Gregg Finding Quasar Pairs 2’ SDSS quasar @ z =2.17

  8. Statistical Clustering Sample Subset of full sample with quantifiable selection criteria 38 binaries below fiber collision limit ( < 55”; R< 400 kpc/h) Statistical Clustering Sample Dense sampling of this region Sparse sampling of this region Pairs found from SDSS Binary Quasars in the SDSS Full Binary Sample Barely Resolved ( = 3”) Fiber collision ( = 55”) Full Binary Sample • 26 new binaries with R < 50 kpc/h ( < 10”) • More than doubles the number of such systems known!

  9. Factor ~ 10 excess for R < 40 kpc/h. Rises to ~ 30 for R ~ 10 kpc/h Quasar correlation function progressively steepens for R < 1 Mpc/h Is excess clustering the hallmark of mergers and dissipative interactions? High redshift galaxies (z = 1- 3) show no excess clustering, but measurements don’t yet probe R < 100 kpc/h Excess Small Scale Clustering Ratio of Observed/Extrapolated Projected Correlation Function Uncertain selection function for smallest angles Fiber Collision Extrapolation of larger scale 2dF clustering Hennawi et al. (2005)

  10. Future Directions • Use photometric selection to measure clustering with better statistics • Push to high redshift binary quasars at z > 4 • Deep imaging to study the environments of these systems. Proto-clusters at z ~ 2? • Measure transverse small scale Ly forest correlations with quasar pairs with z > 2

  11. Low-z galaxies lie on a single power law down to 10 kpc/h (comoving) High redshift (DEEP2, LBGs) clustering does not probe < 100 kpc/h Quasar-Galaxy correlations do not yet probe relevant scales or redshifts Excess Galaxy Clustering? SDSS Galaxies z ~ 0.1 DEEP2 Galaxies z = 0.7-1.35 Coil et al. (2004) Masjedi et al. in prep LBGs at z ~ 3 Adelberger (2003)

  12. z=1.734 B A G1 D C HST ACS HST NICMOS The Widest Lensed Quasar Largest Splitting  = 14.6”! • SDSS spectroscopic survey • 4000 deg2 • 45,000 low -z quasars i < 19.1 • 5,000 z > 3 quasars i < 20.2 • Precise 5 band (u,g,r, i, z) photometry Inada et al. (2003) Oguri et al. (2004) Inada et al. (2005)

  13. How Many Quasars Lensed by Clusters? • Predict ~ 2 lenses with  > 10” in current (~ 4000 deg2) sample • Consistent with discovery of quad lens SDSS 1004+4112 SDSS Photometric Quasars SDSS Spectroscopic Quasars • Predict ~ 8 lenses with  > 10” in current (~ 7000 deg2) sample • ~ 1 should have  > 30” • ~ 1 will have zs ~ 4 From Ray Tracing Simulations through LCDM clusters Hennawi, Dalal, & Bode (2005)

More Related