The Evolution of High-redshift Quasars

Size: px

Start display at page:

Download "The Evolution of High-redshift Quasars"

Dulcie Hancock
6 years ago
Views:

1 The Evolution of High-redshift Quasars The Properties of Early Universe as Revealed by 50 Years of Quasar Research Donald Schneider Penn State Department of Astronomy and Astrophysics September 2013

2 The Evolution of High-redshift Quasars Discovery of High Redshift Quasars The path to z ~ 3.5 Introduction of Digital Technology High-Redshift Quasar Luminosity Function Evolution of the Accretion Process Encountering the Dark Ages To Redshift Seven. And Beyond!

6 A Brief History of the Quest for the Most Distant Quasar Until 1987 the most distant known quasars were all initially identified via radio emission 3C 273 (0.16, 1963) à PKS (3.78, 1982) High-speed computers (1 MHz) and digital scanned plates/ccds allowed large-area, red surveys Q (3.80, 1987) à PC (4.90, 1991) The SDSS combined sensitive digital imaging and multiobject spectroscopy over 10,000 sq deg SDSS 0338 (5.00, 1999) à SDSS 1148 (6.41, 2002) Optical/Infrared surveys became effective recently CFHQS 2329 (6.43, 2007) à ULAS 1120 (7.09; 2011)

7 Explorers of the Edge of the Cosmos

8 Hale Telescope/4-Shooter (1984)

9 Apache Point Observatory

10 SDSS Quasar Target Selection Algorithm Richards et al (2002)

11 Plugging an SDSS-I/II Plate

12 UKIDSS/SDSS Data Used to Discover ULAS z = D. Mortlock et al (2011)

16 High-Redshift Quasar Luminosity Function Early work by M. Schmidt ( ) revealed a rapid rise in the quasar number density [ (1+z)^6 ] to z ~ two. Patrick Osmer s 1982 survey found zero 3.7 < z < 4.7 quasars instead of the 9-22 objects expected from extrapolations of low redshift luminosity function. By the early 1990s several groups (e.g., Warren, Schmidt, Djorgovski) had detected sufficient numbers of high-redshift quasars to measure the steep decline in the z>3.5 high-redshift luminosity function. Samples of quasars from redshifts have now been assembled (e.g., Willott, McGreer) and the LF decline continues (and may be accelerating!)

17 Maarten Schmidt 1970

18 Patrick Osmer 1982

19 Early Measurements of the z>3.5 Quasar Luminosity Function : Warren et al, Schmidt et al, Kinnefick et al

20 Early SDSS High-redshift Quasar Luminosity Functions Fan et al (1999) Richards et al (2006)

21 Quasar Luminosity Function Results from McGreer et al (2013) QLF at <z> = 4.9 Luminous Quasar LF

22 The Quasar Energy Mechanism: The Growth of Supermassive Black Holes Ed Turner s 1991 study of the theoretical implications of the presence of billion solar mass black holes at z ~ 4. UV/Optical spectra of quasars show little or no evidence for change from 0 < z < 7 (early metal enrichment). Relative contribution of X-ray to optical luminosities is essentially independent of redshift.

23 1991: Ed Turner s Analysis of the Newly- Discovered Population of z ~ 4 Quasars

24 - SDSS Low-redshift Composite spectrum

25 No Evidence of Evolution of the Accretion Mechanism from X-ray Observations Steffen et al (2006)

26 High-redshift Quasars and the Intergalactic Medium 1971: Observations of the most distant known quasar (5C 05.34) reveal the Lyman-alpha forest (C.R. Lynds) 1990: Spectra of the recently discovered z>4 quasars show that over half of the flux is absorbed by the LAF. 2001: Detection of the Gunn-Peterson trough in z~6 quasars, encountering the era of the end of hydrogen reionization. 2011: Possible detection of IGM damping wing in z =7.09 quasar spectrum.

27 Discovery of the Lyman-alpha Forest

28 Indications of rapid increase of H I Opacity at z ~ 4

29 Detection of Gunn-Peterson Troughs in z ~ 6 Quasars in 2001 Becker et al (2001)

30 Rapid increase in H I Opacity at z ~ 6 Fan et al (2006)

31 To Redshift Seven... And Beyond! Finding z > 7 quasars presents several challenges Essentially no observed radiation shortward of Lyman-alpha, which occurs at one micron Objects are faint (J > 20) Objects appear to be exceedingly rare [LF(z=6) is ~ a factor of five below LF(z=5)] Require sensitive, wide-area infrared surveys Astronomers faced similar situation in the mid-1980s!

32 Next Generation High-redshift Quasar Surveys Optical Surveys: Limited to z < 6.5 Red-Sensitive CCDs: Reach z ~ 7.5 Improved QE at 1 micron (Y band) SUBARU/HSC (2012): 100s sq deg, Y<25 Pan-Starrs (2009): sq deg, Y<22.5 LSST (2022): sq deg, Y<25 Near Infrared Surveys UKIDSS (2005): 7500 sq deg, J(AB)<21 VISTA/VHS (2010): sq deg, J(AB)<21 ECULID/WFIRST: sq deg, J(AB)<24 (X. Fan)

33 What have we learned from 25 years of z>4 quasar research? The number density of quasars drops dramatically at z > 3, and the rate of decline is accelerating at z ~ 6 Billion solar mass black holes can form within a Gigayear of the Big Bang There does not appear to be any significant change in the physical process of supermassive black hole accretion over the age of the universe Rapid metal enrichment occurs in the environments of supermassive black holes Key epoch of the H I reionization of the IGM appears to occur at 6 < z < 8

Probing the End of Dark Ages with High-redshift Quasars. Xiaohui Fan University of Arizona Dec 14, 2004

Probing the End of Dark Ages with High-redshift Quasars Xiaohui Fan University of Arizona Dec 14, 2004 High-redshift Quasars and the End of Cosmic Dark Ages Existence of SBHs at the end of Dark Ages BH