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Redshift sox: The beginning of an STScI softball team?

Redshift sox: The beginning of an STScI softball team?. Sangeeta Malhotra. Contact Andy Fruchter. Redshift six: the beginning of the universe as we know it?.

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Redshift sox: The beginning of an STScI softball team?

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  1. Redshift sox:The beginning of an STScI softball team? Sangeeta Malhotra Contact Andy Fruchter

  2. Redshift six: the beginning of the universe as we know it? GRAPES/PEARS: James Rhoads, Nor Pirzkal, Chun Xu, Anton Koekemoer, Kailash Sahu, Nino Panagia, Rachel Somerville, Lexi Moustakas, Mark Dickinson, John Gardner, Gerhard Meurer, Caryl Gronwall, Zlatan Tsvetanov, Tamas Budavri, LALA: James Rhoads, Junxian Wang,Katarina Kovac, Elizabeth Barker, Colin Norman, Tim Heckman, Mario Livio. UDF team: Steve Beckwith, Harry Ferguson, Anton Koekemoer, Massimi Stiavelli & Roberto, Shardha Jogee, Megan Sosey, Eddie Bergeron…. OPO: Ann Feild, Skip Westphal, John Bedke, Cheryl Gundy, Zolt Levay, Ray Villard Archives: Karen Levay, Inga Kamp… GLARE: Karl Glazebrook (Apologies to the forgotten collaborator…) Reionization or a phase transition at z~6

  3. Redshift six: the beginning of the universe as we know it? GRAPES/PEARS: James Rhoads, Nor Pirzkal, Chun Xu, Anton Koekemoer, Kailash Sahu, Nino Panagia, Rachel Somerville, Lexi Moustakas, Mark Dickinson, John Gardner, Gerhard Meurer, Caryl Gronwall, Zlatan Tsvetanov, Tamas Budavri, A. Cimatti, E. Daddi, I. Ferreras, Z. Haiman, M. Kuemmel, A. Pasquali, S. di Serego Aligheri, J. Vernet, J. Walsh, R. Windhorst, H.J. Yan LALA: James Rhoads, Junxian Wang,Katarina Kovac, Elizabeth Barker, Colin Norman, Tim Heckman, Mario Livio, Steve Dawson, Dan Stern, Arjun Dey, Buell Jannuzi, Hy Spinrad. UDF team: Steve Beckwith, Harry Ferguson, Anton Koekemoer, Massimi Stiavelli & Roberto, Shardha Jogee, Megan Sosey, Eddie Bergeron…. OPO: Ann Feild, Skip Westphal, John Bedke, Cheryl Gundy, Zolt Levay, Ray Villard Archives: Karen Levay, Inga Kamp… GLARE: Karl Glazebrook, Stanway, Bunker, Abraham et al. (Apologies to the forgotten collaborator…) Sangeeta Malhotra

  4. Reionization: • What: • Who: • Sources of reionization. • Clustering of sources of ionization. • When: • CMB • Gunn Peterson • Lyman-alpha galaxies

  5. I. Reionization: what is it? The word you've entered isn't in the dictionary. Click on a spelling suggestion below or try again using the search box to the right.Suggestions for reionization: 1. lionization 2. reinsertion 3. reanimation 4. lionizations 5. realization 6. renunciation 7. rhinestone 8. reignitions 9. reinsertions 10. reanimations also plural sox /'säks/ : a knitted or woven covering for the foot usually extending above the ankle and sometimes to the knee

  6. The Gunn-Peterson effect: (Gunn & Peterson 1965)

  7. The Gunn-Peterson Test

  8. Detection of G-P trough. • The detection of Gunn-Peterson trough(s) in z ~ 6 quasars show the late stages of H reionization (Becker et al. 2001, Fan et al. 2002.)

  9. Ultra Deep Field The Renaissance after the Dark Ages “Dark Ages” Hubble Deep Field primordial galaxy Here Now S1 Big Bang (re) combination normal galaxy H I H II z ~ 6-10 z ~ ∞ TIGM~ 4z K TIGM~ 104 K z ~ 103 t z Mike Fall

  10. Need to go faint: • GO back to redshift z > 6 and account for photons needed for reionization • See ordinary galaxies, i.e. fainter than L*, because they make up most of the photons needed. Yan & Windhorst 2004 Need to go red: Because of redshifting of the spectra and the IGM absorption.

  11. H U D F

  12. Reionization Results from the HUDF images: • Bunker et al : count galaxies to magnitude 28.5 mag. (WYSIWYG) and fall short by a factor of 3. • Yan & Windhorst: Go fainter (30.5 mag) and attempt correction for incompleteness. Enough photons. • See also Bouwens et al. 2004ab Residual uncertainty: reliability and completeness of I-drop sample

  13. GRism ACS Program for Extragalactic Science (GRAPES) Deepest Unbiased Spectroscopy yet. I(AB) < 27.5 To match the deepest imaging (Hubble Ultra Deep Field) Team: S. Malhotra, James Rhoads, Nor Pirzkal, Chun Xu A. Cimatti, E. Daddi, H. Ferguson, J. Gardner, C. Gronwall, Z. Haiman, A. Koekemoer, L. Moustakas, A. Pasquali, N. Panagia, L. Petro, M. Stiavelli, S. di Serego Aligheri, Z. Tsvetanov, J. Vernet, J. Walsh, R. Windhorst, H.J. Yan

  14. 40 orbits of UDF observations with the ACS grism • Spectra for every source in the field. • Good S/N continuum detections to I(AB) ~ 27.5 • 10 times deeper than ground-based : Keck, Gemini, VLT • about 15% of UDF sources ~ 1500 spectra with good s/n • Spectral identification of every z=4-7 object to I(AB)=27.5 • Moderate redshift ellipticals z~1-2 • Emission line galaxies • Reduced spectra available from HST archives: http://archive.stsci.edu/prepds/udf/udf_hlsp.html

  15. Advantages of HST/ACS combination: • Low sky background from space • Red sensitivity of the ACS • High redshift galaxies are compact, spatial resolution of HST helps. • Contiguous wavelength/redshift coverage, unlike ground based instruments. Improvements in data reduction

  16. GRAPES sample(A nice science free slide) If only slitless extraction was that easy...

  17. Complications • Each pixel has all of the sky and about 1/100th of the object flux. • 3-D flat field; sky is a different color. • High chance of overlap of spectra.

  18. Solutions and Improvements • Made a supersky and subtract that first. • Flatfield after extracting each spectra from each exposure, then combine: first 1-D then 2-D • Minimize contamination with 2-4 orient angles 90 degrees apart. • Estimate contamination from broad-band colors of neighbouring objects • Optimal extraction. • All improvements in the new aXe extraction software aXe 1.5, thanks to our colleagues at ST-ECF: Jeremy Walsh and Martin Kuemmel. aXe 1.7 will write ApJ letters after extracting the spectra

  19. A Spiral galaxy at z=0.3 Direct image | Dispersed image

  20. Experimental design (Pirzkal et al. 2004) Four orients: 0, 8, 90, 98 degrees orient to disentangle overlapping spectra. The agreement between the four orients in wavelength and flux demonstrate accurate flat-fielding and wavelength calibration.

  21. Spectroscopically identified objects: from 600 to 6.7x1010 pc

  22. Salient results from GRAPES PEARS • Too few white dwarfs: < 10% of the DM halo (Pirzkal et al. 2004b) • Ellipticals at z~1 much like z~0 (Pasquali et al. 2005) • Too many Ellipticals at z~2 (Daddi et al. 2005) • Unusually large/interacting object at z=5.5 (Rhoads et al. 2004) • Unusually difficult data set to reduce (Pirzkal et al. 2004a) • Catalog of line emitters at z~1 (Xu et al. 2005) • Luminosity function of [OII] emitters at z~1 (Gronwall et al. in prep) • Line emitters are small, high surface brightness objects (Pirzkal et al. 2005) • z~5 galaxies are not pop-III dominated (Rhoads et al, in prep.) • Large scale clustering at z~6 (Malhotra et al. 2005) Enough photons locally to reionize the intergalactic gas Quantitative statements: need more than one field: (Esp. in view of the large scale structure that we see)

  23. High redshift galaxies With GRAPES we can spectroscopically confirm LBGs to z’(AB)=27-28 depending on the redshift. z=5.5, z=26.9 z=5.8, z=25.1 z=6.4, z=27.8

  24. Reliability of (i-z) selection • 80% for (i-z) > 0.9 • 96% for (i-z) > 1.3

  25. Completeness: color-redshift plot • The (i-z’) generally follows the expected color but there are some blue galaxies: all can be explained by a moderately strong lyman-alpha emission. • Incompleteness implied is about 4/23~20%

  26. A spike in the Redshift distribution (Malhotra et al. 2005) Comparison of observed redshift distribution (histogram) vs. expected numbers The spike at z~6 is at least a factor of two over-dense.

  27. Deep probe vs. Flat-wide probe • Ly-alpha emitters at z=5.7-5.77 observed with mosaic at CTIO • (36’x36’ = 13x13 Mpc) (Wang, Malhotra & Rhoads 2004) • Inhomogeneous distribution • UDF is at the edge of it

  28. Luminosity function at the overdensity • Star-formation rate density for this over-dense region is 2-4x10-2 MO/Mpc3/year • This is enough to drive re-ionization in this “local” over-density.

  29. Reionization : when • When was reionization? • Gunn-Peterson effect z~6 • WMAP polarization z~17 • How fast was it? • How homogeneous? • We need to agree of a definition of reionization! Lyman- galaxy test: local, scaleable relevant at neutral fractions of <f(HI)>~0.5

  30. The Lyman- ReionizationTest Ionized IGM Continuum Photons To Youngstarburst Observer Lyman- photons

  31. The Lyman-Test Neutral IGM Continuum Photons To Youngstarburst Observer Lyman- photons (Miralda-Escude 1998; Miralda-Escude & Rees 1998; Haiman & Spaans 1999; Loeb & Rybicki 1999)

  32. The Lyman- Test, First Order Concerns: HII Regions Neutral IGM Continuum Photons H II region To Youngstarburst Observer Lyman- photons (Madau & Rees 1999; Rhoads & Malhotra 2001; Haiman 2002)

  33. theorists! Ly- lines were expected to be invisible in a neutral IGM until Hu et al. 2002 found a source at z=6.6. Then everyone rushed to explain why we could see Ly- even in a neutral IGM: ionized bubbles, winds … But hard to avoid attenuation of factors of 2-3 (Santos 2004) How do you know that any individual object was not intrinsically brighter? Statistical test on the population

  34. Lyman- Luminosity Functions • Luminosity function fits on all available data at z=5.7 and 6.5 • Santos et al. 2004, Taniguchi et al. 2004, Rhoads et al. 2004, Kurk et al. 2004, Tran et al. 2004, Hu et al. 2002, Hu et al. 2004, Ajiki et al. 2004, Rhoads et al. 2003, Rhoads & Malhotra 2001 (few tens of nights on large telescopes) • z = 6.5 plot shows two hypotheses: • z = 5.7 LF, or • z = 5.7 LF reduced by a factor of 3 in luminosity to approximate IGM absorption. • No evidence for neutral IGM!

  35. MR99 MR03 Charting Reionization There is no contradiction between the GP effect at z=6.2 and the Ly test at z=6.5; remarkable agreement with the dark gap tests (Fan et al. 2005)

  36. 1st order concern 1.Cosmic variance in samples Monte Carlo simulations to account for cosmic variance: All observed densities allowed to vary by factor of 2. • Circles: z = 5.7 • Triangles: z = 6.5 • Squares: z = 5.7 with L* divided by 3.

  37. 1st order concern 2.Picket fence effect Suppose you obliterate some fraction of the sources completely, and the other half remains untouched in luminosity. Then phi* should decrease - it is seen to increase slightly at z=6.5 compared to z=5.7

  38. Concern 3: redshift evolution: none! LALA Lum Fn at z=4.5 LALA Lum fn at z=4.5 (Dawson et al. 2005)

  39. 4. Bright end of luminosity function • Biggest changes expected at the bright end of the luminosity function! • See Haiman & Cen 2005, for luminosity dependent attenuation: the conclusions do not change significantly. • Furlanetto et al. 2005, conclude that neutral fraction is 50% compared to ~30% as in MR04.

  40. Concern 5: Clustering around Ly-a sources • What about clustering and Stromgren spheres created by unseen sources around Lyman-alpha emitters at z=6.5? • Need to boost the ionizing flux by a factor of 10: possible in simulations: Wyithe & Loeb 2004, Furlanetto et al. 2004: • deep ACS imaging around one z=6.5 source shows no dramatic overdensity (Rhoads et al. in prep.) Stiavelli et al. 2005 see an overdensity at z=5.9 around a Sloan quasar at z=6.2 Agnostic about this possibility

  41. Mapping Ionized and Neutral Gas with Lyman Alpha Galaxies • We can map the distribution of Lyman alpha galaxies over large scales… • This may map out bubbles of ionized gas in the overlap phase of reionization.

  42. Mapping Ionized and Neutral Gas with Lyman Alpha Galaxies • A control sample of Lyman break selected galaxies will be useful (green dots, below).

  43. Topology of Reionization from Lyman Alpha Galaxies • The overlap phase is a topological change in the ionized gas distribution. • Use topological statistics-- the Genus number Figure after Gott, Weinberg, & Melott 1987

  44. Galaxies at z~5-6

  45. Malhotra et al. 2005, Pirzkal et al. 2006.

  46. First and Last word about Pop-III=> Spectral slopes of UDF faint galaxies (Rhoads et al. 2005) The composite spectrum of z=4-5 objects in the UDF is shown by the white line. The Lyman break sample (Shapley et al.) at z=3 is shown in yellow for comparison and one of the bluest nearby galaxies NGC 1705 is shown in blue.

  47. Old Stellar populations at z~6: Spitzer GOODS data: Yan et al. 2005, also Eyles et al. 2005, Egami et al. 2005. Star-formation at z>10 Need to quantify this!

  48. Old Stars and Dust? Spitzer weighs in (Mobasher et al, 2005):

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