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Millimeter/Submillimeter Studies of High-Redshift Galaxies

Millimeter/Submillimeter Studies of High-Redshift Galaxies. Deciphering the Ancient Universe with Gamma-Ray Bursts April 20, 2010, Kyoto, Japan. Kotaro KOHNO IoA/BBC, Univ. of Tokyo kohno@ioa.s.u-tokyo.ac.jp. Title image: Yoichi Tamura. Outline.

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Millimeter/Submillimeter Studies of High-Redshift Galaxies

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  1. Millimeter/Submillimeter Studies of High-Redshift Galaxies Deciphering the Ancient Universe with Gamma-Ray Bursts April 20, 2010, Kyoto, Japan Kotaro KOHNO IoA/BBC, Univ. of Tokyo kohno@ioa.s.u-tokyo.ac.jp Title image: Yoichi Tamura

  2. Outline • Why we observe high-z galaxies at millimeter/submillimeter wavelengths? • Mm/submm selected galaxies (SMGs), one of the most massive populations in the early universe, with highly elevated star formation rates (SFRs) • Recent hot topics, such as clustering and dark halo masses, redshifts, ultra-bright populations, etc. • AzTEC on ASTE survey of SMGs • Mm/submm studies on GRB host galaxies, a metal poor, less massive population in the early universe • Probing a molecular gas and hidden star formation

  3. Why we observe high-z galaxies at millimeter/submillimeter wavelengths?

  4. Because a large portion of the cosmic star formation is obscured by dust Observed SFR True SFR More hidden star formation @higher redshift (>70% at z~1) Dust @IR @UV Based on the comparison of Lum. Functions at FUV with GALEX & IR with IRAS/Spitzer Star formation rate density [Mo/yr/Mpc3] Takeuchi, Buat, & Durgarella 2005, A&A, 440, L17 redshift

  5. And because mm/submm is the best to unveil the dust obscured star formation in the early universe Rapid dimming at optical/IR/radio wavelengths for higher z Almost constant flux at mm/submm

  6. K correction as a function of λ • Almost constant flux for ~1 < z < ~10 at 850um/1.1mm due to strong negative K correction • 1.4 GHzintensity drops very rapidly：S(z) ~ (1+z)-(4+α) • α ~ 0.8 (Condon 1992 ARAA, 30, 575) 850um 1.1mm Flux density [mJy] 24um Blain et al., 2002, Physics Reports, 369, 111-176 redshift

  7. Deep survey in optical wavelengths

  8. Deep survey with ALMA (simulation)

  9. AzTEC/ASTE 1.1mm map of ADF-S SNR Hatsukade et al., 2010, poster #26 1σ < 0.6 mJy 1σ < 0.8 mJy (970 arcmin2) 0.5 deg

  10. AzTEC/ASTE 1.1mm map of ADF-S SNR Hatsukade et al., 2010, poster #26 • 181 detections (above 3.5 σ) • 101 of them exceed 5 σ 1σ < 0.6 mJy 1σ < 0.8 mJy (970 arcmin2) 0.5 deg

  11. Constraints on redshifts of AzTEC/ASTE sources in ADF-S • 90um/1.1mm flux ratio  most of the AzTEC sources: z > 1 • AKARI 90um sources : low-z, AzTEC 1.1mm sources: high-z • L(FIR) ~ (3-14) x 1012 Lo, SFR ~ 500-2400 Mo/yr AKARI AzTEC 90um/1.1mm flux ratio

  12. AzTEC-on-ASTE surveysof Submillimeter galaxies (SMGs) AzTEC Camera, 144 pix, 1.1mm, FOV=8’, θ=28” (Wilson et al. 2008) ASTE10m (Ezawa et al. 2008)

  13. Collaborators • Kohno, K., Hatsukade, B., Ikarashi, S., Tsukagoshi, T., Inoue, H. (Univ. of Tokyo), • Kawabe, R., Tamura, Y., Oshima, T, Nakanishi, K., Ezawa, H., (NAOJ), Komugi, S. (ISAS/JAXA), Tanaka, K. (Keio Univ.), & ASTE team • Cortes, J., (JAO), Bronfman, L. (Univ. of Chile) • Wilson, G.W., (PI. of AzTEC; UMASS), Aretxaga, I., Hughes, D.H., (INAOE), Yun, M.S., Austermann, J., Scott, K.S. (UMASS), Perera, T. (Univ. of Chicago), & AzTEC team • ADF-S/SXDS/SDF/SSA22 collaborations

  14. AzTEC-ASTE 1.1 mm deep surveys （+ HDF-S, ECDF-S） • wide (~1.6 deg2) & deep (1σ ~ 0.4 – 1.2 mJy ⇔ ULIRGs @z>1) surveys of blank fields: yielding >750 robust detections • Biased regions survey: ~1 deg2, >680 detections • High-z radio galaxies, X-ray and optically selected proto-clusters; ~160 arcmin2 x ~40 fields: >1400 detections in total, ~x3 of the known (published) SMGs

  15. Highlights from our SMG surveys • Clustering properties of SMGs; relation to the underlying dark halo distribution • Infrared-dark SMGs: extreme starburst populations that are invisible at optical/near-infrared wavelengths • “Flat spectrum” SMGs: another candidates for high-z SMGs? (z>4) • Extremely bright SMGs

  16. Highlights from our SMG surveys • Clustering properties of SMGs; relation to the underlying dark halo distribution • Infrared-dark SMGs: extreme starburst populations that are invisible at optical/near-infrared wavelengths • “Flat spectrum” SMGs: another candidates for high-z SMGs? (z>4) • Extremely bright SMGs

  17. Bright SMGs in SSA22 by AzTEC/ASTE Lyman Alpha Emitters ASTE SUBARU SMGs LAEs SFR ~ a few 100 – a few 1000 Mo/yr SFR ~ a few Mo/yr Distribution of LAEs Around z~3.1 Nakamura et al. Tamura et al., 2009, Nature, 459, 61 No one-by-one correspondence to LAEs, but clustered at the LAE density peak

  18. Clustering of SMGs toward the biased region traced by LAEs Y. Tamura et al., 2009, Nature, 459, 61 1.1mm image Bright SMGs on Lyα emitters at z~3.1

  19. Angular cross correlation between SMGs & LAEs • Landy & Szalay’s estimator • probability of finding a source of the other population at distance θ • A clear detection of cross correlation signal with z=3.1 LAEs  detected bright SMGs in SSA 22 are also clustered around z~3 ! correlation signal at θ < 5 ‘ Tamura et al., 2009, Nature, 459, 61

  20. Tracing the heart of massive dark halo with SMGs • Structure formation w/ Λ cold dark matter model • young, less massive galaxies (LAEs) are falling into the heart of the massive dark halo • Massive starburst galaxies (SMGs) are grown there Dark halo LSS LAEs SMGs

  21. Clustering of SMGs(auto correlation of SMGs) • Previous studies on SMGs • Tentative detections • amp. = 4.4±2.9 • amp. = 4. 9±2.8 • AzTEC Sources in ADF-S and SXDF • All sources • >3mJy sources L(IR) ~ 1013 Lo (Webb+03) (using 50 sources; Webb+03) (Weiss+09) (using 126 sources; Weiss+09) Hatsukade 2010, PhD thesis See also Poster #26

  22. Distribution of all/bright SMGs in ADF-S • Distribution of bright SMGs deviates from random distribution! Bright sources only

  23. Clustering of AzTEC Sources • Evidence for clustering • Bright sources (L(FIR) ~ 1013) are more strongly clustered • DH mass: 1013-14 Mo • Field-to-field variance • ADF-S > SXDF Hatsukade 2010, PhD thesis; see poster #26 ω（θ） >3mJy sources in combined data θ[arcsec]

  24. Highlights from our SMG surveys • Clustering properties of SMGs; relation to the underlying dark halo distribution • Infrared-dark SMGs: extreme starburst populations that are invisible at optical/near-infrared wavelengths • “Flat spectrum” SMGs: another candidates for high-z SMGs? (z>4) • Extremely bright SMGs

  25. Optical/infrared properties of SMGs • Optically faint/often invisible • Very red color in infrared (NIR/Spitzer MIR bands also) SXDF 850.6, SMA contours on optical/infrared/radio images Hatsukade et al. 2010, ApJ, in press

  26. Extremely dark SMGs • The brightest guy in SSA22 is invisible/faint in near infrared down to KAB~25 mag ! • despite of their extremely elevated SFRs (~a few 1000 Mo/yr), they are not identified by existing deep optical/NIR surveys with 4-8 m class telescopes !!! • Recnet AzTEC-ASTE surveys as well as previous SCUBA surveys unveil the presence of such dark populations of massive starbursts

  27. SMA 860μm Multi-wavelengths ID of the brightest SMG in SSA22 Ks > 24.9 mag(AB), 2σ upper limit • very “red” in MIR(IRAC) bands ! • K-drop out !? even with SUBARU Color ：Spitzer/IRAC Contour ：VLA 20cm Color： 2um Subaru/MOIRCS (Uchimoto et al., 2008) Contour ：SMA 860μm Y. Tamura et al. 2010, submitted

  28. “K-drop SMG” with elevated SFR >1000 Mo/yr Y. Tamura et al. 2010 submitted SMA • Detection of a deeply obscured (NH~1024cm-2) hard X-ray source  proto-quasar phase? Growing SMBH? • SED  Mstar ~7x1010 Mo  growing bulge? Stellar AGN MIPS AzTEC/ASTE Nobeyama (NMA) Spitzer IRAC VLA It is very surprising that this kind of monster can’t be uncovered with existing NIR deep surveys! ULIRG SED templates at z = 3.1 SUBARU MOIRCS

  29. Another K-band drop SMGs in literature • No K band counterpart even after deep integration using MOIRCS/SUBARU “GOODS-N 850.5” or “GN10” Wang et al. 2009, ApJ, 690, 319 Daddi et al., 2009, ApJ, 695, L176 (z_spec=4.04)

  30. Further example of K-drop SMGs • HDF850-1: Cowie et al., 2009, ApJ, 697, L122

  31. SED of HDF850.1 S850um ~7.8 ± 1.0 mJy • z~4.1±0.5 is suggested Cowie et al. 2009, ApJ, 697, L122

  32. Highlights from our SMG surveys • Clustering properties of SMGs; relation to the underlying dark halo distribution • Infrared-dark SMGs: extreme starburst populations that are invisible at optical/near-infrared wavelengths • “Flat spectrum” SMGs: another candidates for high-z SMGs? (z>4) • Extremely bright SMGs

  33. Submm/mm flux ratiosas a rough indicator of redshift Steeper  low z Flatter  high z

  34. High-z SMG candidates in SXDF • “Flat spectrum” SMGs: 850um/1100um flux ratio < 1.8 (i.e., flatter than a typical slope) • Combined analysis of SHADES and AzTEC-ASTE sources • ~20 % of the total SCUBA sources are “flat” (<1.8) • Many of them are 20cm faint Kohno, Ikarashi et al. 2010, in prep. ○: AzTEC ○: SCUBA AzTEC/ASTE SN map

  35. High-z SMG candidates in GOODS-S • 870um; LABOCA on APEX: Weiss et al. 2009, ApJ, 707, 1201 • 1.1mm: AzTEC on ASTE: Scott et al., 2010, MNRAS, in press. • Low ratio (flat spectrum) SMGs  z>5SMGs !? ○AzTEC ×Laboca

  36. The highest redshift SMGs known • z=4.76, LESS J0332-2756, by LABOCA/APEX • Coppin et al. 2009, MNRAS, 395, 1905 • z=4.54, COSMOSJ1000+0234 by AzTEC/JCMT • Capak et al. 2008, ApJ, 681, L53 for optical spec. • Schinnerer et al. 2008, ApJ, 689, L5 for CO spec. • z=4.042, GOODS-N850.5, by SCUBA/JCMT • Daddi et al. 2009, ApJ, 695, L176 z=4.76 SMG: Optical (left) IRAC (middle) 24 um + 870um contour (right)

  37. Too many high-z SMGs already !? • Known number of the high-z (z>4) SMGs are already consistent to a L-CDM model prediction !? • Number of high-z (z>4) SMGs can put tight constraint on models z~2 SMGs (Chapman et al. 2005) Volume density Φ [Mpc^-3] z>4 SMGs Solid line: Model prediction by Baugh et al. 2005 MNRAS, 356, 1191 • Coppin et al. 2009, • MNRAS, 395, 1905 Redshift

  38. Further evidence for the presence of high-z SMGs • Infrared faint SMGs • Reports on SMGs without K-band counterpart • ~1/4 of the AzTEC/ASTE SMGs in SXDF seems K-band faint, i.e., another high-z SMG candidates! • Flat 850/1100um spectrum SMGs • Higher-z  flatter spectrum (small flux ratio) • Radio faint SMGs (see Younger et al. 2007) • High angular resolution submillimeter imaging with SMA  pinpoint the accurate position of SMGs  5 of 7 bright SMGs are radio faint (i.e., high z)

  39. Highlights from our SMG surveys • Clustering properties of SMGs; relation to the underlying dark halo distribution • Infrared-dark SMGs: extreme starburst populations that are invisible at optical/near-infrared wavelengths • “Flat spectrum” SMGs: another candidates for high-z SMGs? (z>4) • Extremely bright SMGs

  40. Brightest end of number count • Very wide area survey  rare population • Detection of 33 mJy@1100um source@SXDF ⇔ ~70 mJy (!) @850um • A dozen of >10 mJy sources (⇔ >20 mJy source@850um) • cf. the brightest SMGs in SHADES (@850um) • [22 mJy], 14 mJy, 13 mJy, 13 mJy, 11 mJy, … • Majority: less than 10 mJy • New observational constraints on: • Brightest end of galaxy number count • Extreme starburst (up to ~10000 Mo/yr ?!)

  41. The brightest SMG in SXDF Ikarashi et al., in prep. • ~80 mJy source @870 um • Brighter than Cloverleaf quasar, comparable to recently reported LABOCA source (at z=2.3, Swinbank et al. 2010, Nature, in press) • No evidence for strong amplification by a gravitational lens • low Tdust, gas rich object, moderate SFR  a young SMG? (if z~1) • A genuine, intrinsically bright • extreme starburst? (if z~3) • Maximum SB? • (e.g., Thompson 2005)

  42. Ultra-bright SMGs @low-z clusters?? Wilson et al., 2008, MNRAS, 390, 1061 • Bullet cluster (z=0.297) 1 arcmin Ezawa, Oshima, et al., in prep. The brightest one: Close to the mass peak  z~2 SMG amplified by lens? Collaboration with Weak lensing How about another Ultra-brights?

  43. Millimeter/submillimeter Studies of GRB host galaxies

  44. Molecular gas in GRB host galaxies • A search for molecular gas via CO emission at mm/submm in GRB host galaxies: fairly tricky (or crazy) business because CO is difficult to detect in low metallicity environment. • Nevertheless, we were motivated because there was evidence for a dust-obscured star formation in some of GRB host galaxies. • CO detection yields: Mgas, Mdyn, (CO abundance), • star formation efficiency (= SFR/Mgas) cf. SSFR (= SFR/M*)

  45. SFRs in GRBs: obscured star formation? SFRs from extinction corrected Halpha luminosity SFRs from submm (SCUBA/JCMT) measurements huge discrepancy! Molecular gas ? [OII] [OII] Berger et al. 2003, ApJ, 588, 99 Overestimation @ submm/radio? or obscured star formation invisible in optical wavelengths?

  46. GRB000418: ULIRG like host? Berger et al. 2003, ApJ, 588, 99 • One of the most strongest SCUBA sources among GRB host galaxies (?) • Radio detection SFR @ submm 690±195 Mo/yr SFR @ radio 330±75 Mo/yr SFR @ optical 55 Mo/yr • - z = 1.118 • - sub-luminous (L～ 0.6 L* ) • ULIRG like • LFIR /L1600 ratio 1”=8.2kpc

  47. PdBI CO(2-1) in GRB000418 1 sigma = 4.2 mJy/beam • PdBI Observations, no detection after 2 hours integration • CO(2-1) luminosity 3σ upper limit: L’co(2-1) < 1.9 x 1010 K km/s pc2 • M(gas) < 2x1010Mo, SFR<90 Mo/yr if this is ULIRG-like • i.e., velocity width = 300 km/s, CO(2-1)/CO(1-0) ratio = 0.9, Xco=0.8 Mo/(K km/s pc2) + KS law, also assumes CO emitting region size = optical diameter Hatsukade et al. in prep. Inconsistent with SFR from submm, consistent with optical SFR

  48. NMA Another unsuccessful CO search: CO(1-0) in GRB030329 (z=0.17) • No CO emission; 1 sigma ~2mJy/beam for dv=50 km/s Endo, Kohno, et al. 2007, ApJ, 659, 1431

  49. Summary on CO emission search in GRB hosts • GRB000418: search for CO(2-1) by PdBI • M(H2) < 2×1010 M, SFR<90 M/yr • Hatsukade et al., in prep. • GRB030329: search for CO(1-0) by NMA • M(H2) < 2.8×1010 M, SFR < 4-38 M/yr • Endo et al. 2007, ApJ, 659, 1431; Kohno et al. 2005, PASJ, 57, 147 • GRB980425: search for CO(3-2) by ASTE • M(H2) < 3×108 M, SFR<0.1 M/yr • Hatsukade et al. 2007, PASJ, 59, 67 • No CO detection (in emission) in GRB hosts so far. • Consistent with the idea that they are metal poor.

  50. Is [CII] in GRB hosts promising ? LMC • [CII] 157 um/1.9 THz line becomes very bright (i.e., high L[CII]/LFIR ratio) in low metal galaxies • CO is selectively destructed in these low metal star forming galaxies CII/FIR= 1 % M82 CII/FIR = 0.1 % Arp220 0.01 % Maiolino et al., 2009, A&A, 500, L1

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