Chun Ly

The End of the Reionization Epoch Probed by Lyα Emitters at z = 6.5 in the Subaru Deep Field* **

We report an extensive search for Lyα emitters (LAEs) at z = 6.5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at z = 6.5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58 LAEs, we have derived a more accurate Lyα luminosity function of LAEs at z = 6.5, which reveals an apparent deficit at the bright end of ∼0.75 mag fainter L*, compared with that observed at z = 5.7. The difference in the LAE luminosity functions between z = 5.7 and 6.5 is significant at the 3 σ level, which is reduced to 2 σ when cosmic variance is taken into account. This result may imply that the reionization of the universe has not been completed at z = 6.5. We found that the spatial distribution of LAEs at z = 6.5 was homogeneous over the field. We discuss the implications of these results for the reionization of the universe.

COMPLETING THE CENSUS OF Lyα EMITTERS AT THE REIONIZATION EPOCH

We carried out extended spectroscopic confirmations of Lyα emitters (LAEs) at z = 6.5 and 5.7 in the Subaru Deep Field. Now, the total number of spectroscopically confirmed LAEs is 45 and 54 at z = 6.5 and 5.7, respectively, and at least 81% (70%) of our photometric candidates at z = 6.5 (5.7) have been spectroscopically identified as real LAEs. We made careful measurements of the Lyα luminosity, both photometrically and spectroscopically, to accurately determine the Lyα and rest-UV luminosity functions (LFs). The substantially improved evaluation of the Lyα LF at z = 6.5 shows an apparent deficit from z = 5.7 at least at the bright end, and a possible decline even at the faint end, though small uncertainties remain. The rest-UV LFs at z = 6.5 and 5.7 are in good agreement, at least at the bright end, in clear contrast to the differences seen in the Lyα LF. These results imply an increase in the neutral fraction of the intergalactic medium from z = 5.7 to 6.5. The rest-frame equivalent width (EW0) distribution at z = 6.5 seems to be systematically smaller than z = 5.7, and it shows an extended tail toward larger EW0. The bright end of the rest-UV LF can be reproduced from the observed Lyα LF and a reasonable EW0-UV luminosity relation. Integrating this rest-UV LF provides the first measurement of the contribution of LAEs to the photon budget required for reionization. The derived UV LF suggests that the fractional contribution of LAEs to the photon budget among Lyman break galaxies significantly increases toward faint magnitudes. Low-luminosity LAEs could dominate the ionizing photon budget, though this inference depends strongly on the uncertain faint-end slope of the Lyα LF.

The luminosity function and star formation rate between redshifts of 0.07 and 1.47 for narrowband emitters in the subaru deep field

SDF line-emitting galaxies in four narrowband filters at low and intermediate redshifts are presented. Broadband colors, follow-up optical spectroscopy, and multiple NB filters are used to distinguish Hα, [O II], and [O III] emitters at z = 0.07-1.47 to construct their LFs. These LFs are derived down to faint magnitudes, allowing for an accurate determination of the faint-end slope. With a large (N ∼ 200-900) sample for each redshift interval, a Schechter profile is fitted to each LF. Prior to dust extinction corrections, the [O III] and [O II] LFs agree reasonably well with those of Hippelein et al. The z = 0.08 Ha LF, which reaches 2 orders of magnitude fainter than Gallego et al., is steeper by 25%. This indicates that there are more low-luminosity star-forming galaxies for z 1, the SFR densities are similar. The latter is consistent with previous UVand [O II] measurements. Below z < 0.4, the SFR densities are consistent with several Ha, [O II], and UV measurements, but others are a factor of 2 higher. For example, the z = 0.066-0.092 LF agrees with Jones & Bland-Hawthorn, but at z = 0.24 and 0.40, their number densities are twice as high. This discrepancy can be explained by cosmic variance.

Lyα Emitters at z = 5.7 in the Subaru Deep Field

PASJ: Publ. Astron. Soc. Japan , 1–??, c 2008. Astronomical Society of Japan. Lyα Emitters at z = 5.7 in the Subaru Deep Field Kazuhiro Shimasaku, 1,2 Nobunari Kashikawa, 3,4 Mamoru Doi, 5,2 Chun Ly, 6 Matthew A.Malkan, 6 Yuichi Matsuda, 7 Masami Ouchi, 8,‡ Tomoki Hayashino, 9 Masanori Iye, 3,4 Kentaro Motohara, 5 Takashi Murayama, Tohru Nagao, 3,11 Kouji Ohta, 12 Sadanori Okamura, 1,2 Toshiyuki Sasaki, 13 Yasuhiro Shioya, 10 Yoshiaki Taniguchi 10 arXiv:astro-ph/0602614v1 28 Feb 2006 Department of Astronomy, School of Science, The University of Tokyo, Tokyo 113-0033 Email (KS): shimasaku@astron.s.u-tokyo.ac.jp Research Center for the Early Universe, School of Science, The University of Tokyo, Tokyo 113-0033 Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 Department of Astronomy, School of Science, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 Institute of Astronomy, School of Science, The University of Tokyo, Mitaka 181-0015 Department of Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1547, USA Department of Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA Research Center for Neutrino Science, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578 Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan INAF / Osservatorio Astrofisico di Arcetri Largo E. Fermi 5, 50125 Firenze, Italy Kouji Ohta Department of Astronomy, Kyoto University, Kyoto 606-8502 Subaru Telescope, National Astronomical Observatory of Japan, 650 N. A’ohoku Place, Hilo, HI 96720, USA (Received 2005 October 26; accepted 2006 February 27) Abstract We present the properties of Lyα emitters (LAEs) at z = 5.7 in the Subaru Deep Field. A photometric sample of 89 LAE candidates is constructed from narrow-band (NB816) data down to N B816 = 26.0 (AB) in a continuous 725 arcmin 2 area. Spectra of 39 objects satisfying the photometric selection criteria for LAEs were obtained with Subaru and Keck II Telescopes, among which 28 were confirmed LAEs, one was a nearby galaxy, and eight were unclassified. We also obtained spectra of another 24 NB816-excess objects in the field, identifying six additional LAEs. We find that the Lyα luminosity function derived from the photometric sample is reproduced well by a Schechter function with L ⋆ = 7.9 +3.0 erg s −1 and φ ⋆ = 6.3 −2.0 × 10 −4 Mpc −3 for α = −1.5 (fixed) over the whole luminosity range of L ≃ 3 × 10 42 – 3 × 10 43 erg s −1 . We then measure rest-frame Lyα equivalent widths (EWs) for the confirmed LAEs, to find that the median among the 28 objects satisfying the photometric selection criteria is W i0 = 233 ˚ A. We infer that 30% – 40% of LAEs at z = 5.7 exceed W i0 = 240 ˚ A. These large-EW objects probably cannot be accounted for by ordinary star-forming populations with a Salpeter IMF. We also find that LAEs with fainter far-UV luminosities have larger EWs. Finally, we derive the far-UV luminosity function of LAEs down to M UV ≃ −19.6 using the photometric sample, and compare it with that of Lyman-break galaxies (LBGs). We find that as high as about 80% of LBGs at z ∼ 6 have W i0 ≥ 100 ˚ A, in sharp contrast to lower-z counterparts. Key words: galaxies: evolution — galaxies: high-redshift — galaxies: luminosity function, mass function — galaxies: photometry

THE Hα LUMINOSITY FUNCTION AND STAR FORMATION RATE VOLUME DENSITY AT z = 0.8 FROM THE NEWFIRM Hα SURVEY

[Abridged] We present new measurements of the H-alpha luminosity function (LF) and SFR volume density for galaxies at z~0.8. Our analysis is based on 1.18

“DIRECT” GAS-PHASE METALLICITIES, STELLAR PROPERTIES, AND LOCAL ENVIRONMENTS OF EMISSION-LINE GALAXIES AT REDSHIFTS BELOW 0.90

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A Photometric Survey for Lyα-He II Dual Emitters: Searching for Population III Stars in High-Redshift Galaxies

m narrowband data from the NEWFIRM H-alpha Survey, a comprehensive program designed to capture deep samples of intermediate redshift emission-line galaxies using narrowband imaging in the near-infrared. The combination of depth (

Optical and near-IR spectroscopy of candidate red galaxies in two z ~ 2.5 proto-clusters

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A CENSUS OF STAR-FORMING GALAXIES AT z = 1-3 IN THE SUBARU DEEP FIELD

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A VLBA movie of the jet launch region in M87

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