skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: ALMA DEEP FIELD IN SSA22: A CONCENTRATION OF DUSTY STARBURSTS IN A z = 3.09 PROTOCLUSTER CORE

Abstract

We report the results of 1.′5 × 3′ mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array toward the central region of the z = 3.09 SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S{sub 1.1} {sub mm} = 0.7–6.4 mJy (L{sub IR} ∼ 10{sup 12.1}–10{sup 13.1} L{sub ⊙}) are at z = 3.08–3.10. Not only are these SMGs members of the protocluster, but they in fact reside within the node at the junction of the 50 Mpc scale filamentary three-dimensional structure traced by Lyα emitters in this field. The eight SMGs account for a star formation rate density (SFRD) ∼10 M{sub ⊙} yr{sup −1} Mpc{sup −3} in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host an X-ray-luminous active galactic nucleus. Our results suggest that the vigorous star formation activity and the growth of supermassive black holes (SMBHs) occurred simultaneously in the densest regions at z ∼ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Lyαmore » blobs, implying that the two populations coexist in high-density environments for a few cases.« less

Authors:
;  [1]; ; ; ;  [2]; ;  [3];  [4]; ; ; ; ; ; ;  [5];  [6];  [7];  [8];  [9] more »; « less
  1. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)
  2. Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)
  3. Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
  4. Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
  5. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  6. Department of astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
  7. Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen (Netherlands)
  8. Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa City, Chiba 277-8582 (Japan)
  9. Department of Physics, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701 (United States)
Publication Date:
OSTI Identifier:
22518661
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 815; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; BLACK HOLES; CATALOGS; CONCENTRATION RATIO; DENSITY; FLUX DENSITY; GALAXIES; GALAXY NUCLEI; LYMAN LINES; QUASARS; RED SHIFT; STAR CLUSTERS; STARS; UNIVERSE; X RADIATION

Citation Formats

Umehata, H., Ivison, R. J., Tamura, Y., Kohno, K., Izumi, T., Makiya, R., Alexander, D. M., Smail, I., Geach, J. E., Hatsukade, B., Kato, Y., Kawabe, R., Lee, M., Matsuda, Y., Nakanishi, K., Saito, T., Hughes, D. H., Ikarashi, S., Kubo, M., Lehmer, B., E-mail: humehata@eso.org, and and others. ALMA DEEP FIELD IN SSA22: A CONCENTRATION OF DUSTY STARBURSTS IN A z = 3.09 PROTOCLUSTER CORE. United States: N. p., 2015. Web. doi:10.1088/2041-8205/815/1/L8.
Umehata, H., Ivison, R. J., Tamura, Y., Kohno, K., Izumi, T., Makiya, R., Alexander, D. M., Smail, I., Geach, J. E., Hatsukade, B., Kato, Y., Kawabe, R., Lee, M., Matsuda, Y., Nakanishi, K., Saito, T., Hughes, D. H., Ikarashi, S., Kubo, M., Lehmer, B., E-mail: humehata@eso.org, & and others. ALMA DEEP FIELD IN SSA22: A CONCENTRATION OF DUSTY STARBURSTS IN A z = 3.09 PROTOCLUSTER CORE. United States. doi:10.1088/2041-8205/815/1/L8.
Umehata, H., Ivison, R. J., Tamura, Y., Kohno, K., Izumi, T., Makiya, R., Alexander, D. M., Smail, I., Geach, J. E., Hatsukade, B., Kato, Y., Kawabe, R., Lee, M., Matsuda, Y., Nakanishi, K., Saito, T., Hughes, D. H., Ikarashi, S., Kubo, M., Lehmer, B., E-mail: humehata@eso.org, and and others. 2015. "ALMA DEEP FIELD IN SSA22: A CONCENTRATION OF DUSTY STARBURSTS IN A z = 3.09 PROTOCLUSTER CORE". United States. doi:10.1088/2041-8205/815/1/L8.
@article{osti_22518661,
title = {ALMA DEEP FIELD IN SSA22: A CONCENTRATION OF DUSTY STARBURSTS IN A z = 3.09 PROTOCLUSTER CORE},
author = {Umehata, H. and Ivison, R. J. and Tamura, Y. and Kohno, K. and Izumi, T. and Makiya, R. and Alexander, D. M. and Smail, I. and Geach, J. E. and Hatsukade, B. and Kato, Y. and Kawabe, R. and Lee, M. and Matsuda, Y. and Nakanishi, K. and Saito, T. and Hughes, D. H. and Ikarashi, S. and Kubo, M. and Lehmer, B., E-mail: humehata@eso.org and and others},
abstractNote = {We report the results of 1.′5 × 3′ mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array toward the central region of the z = 3.09 SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S{sub 1.1} {sub mm} = 0.7–6.4 mJy (L{sub IR} ∼ 10{sup 12.1}–10{sup 13.1} L{sub ⊙}) are at z = 3.08–3.10. Not only are these SMGs members of the protocluster, but they in fact reside within the node at the junction of the 50 Mpc scale filamentary three-dimensional structure traced by Lyα emitters in this field. The eight SMGs account for a star formation rate density (SFRD) ∼10 M{sub ⊙} yr{sup −1} Mpc{sup −3} in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host an X-ray-luminous active galactic nucleus. Our results suggest that the vigorous star formation activity and the growth of supermassive black holes (SMBHs) occurred simultaneously in the densest regions at z ∼ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Lyα blobs, implying that the two populations coexist in high-density environments for a few cases.},
doi = {10.1088/2041-8205/815/1/L8},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 815,
place = {United States},
year = 2015,
month =
}
  • We report interferometric imaging of [C II]({sup 2} P {sub 3/2}→{sup 2} P {sub 1/2}) and OH({sup 2}Π{sub 1/2} J = 3/2→1/2) emission toward the center of the galaxy protocluster associated with the z = 5.3 submillimeter galaxy (SMG) AzTEC-3, using the Atacama Large (sub)Millimeter Array (ALMA). We detect strong [C II], OH, and rest-frame 157.7 μm continuum emission toward the SMG. The [C II]({sup 2} P {sub 3/2}→{sup 2} P {sub 1/2}) emission is distributed over a scale of 3.9 kpc, implying a dynamical mass of 9.7 × 10{sup 10} M {sub ☉}, and a star formation rate (SFR)more » surface density of Σ{sub SFR} = 530 M {sub ☉} yr{sup –1} kpc{sup –2}. This suggests that AzTEC-3 forms stars at Σ{sub SFR} approaching the Eddington limit for radiation pressure supported disks. We find that the OH emission is slightly blueshifted relative to the [C II] line, which may indicate a molecular outflow associated with the peak phase of the starburst. We also detect and dynamically resolve [C II]({sup 2} P {sub 3/2}→{sup 2} P {sub 1/2}) emission over a scale of 7.5 kpc toward a triplet of Lyman-break galaxies with moderate UV-based SFRs in the protocluster at ∼95 kpc projected distance from the SMG. These galaxies are not detected in the continuum, suggesting far-infrared SFRs of <18-54 M {sub ☉} yr{sup –1}, consistent with a UV-based estimate of 22 M {sub ☉} yr{sup –1}. The spectral energy distribution of these galaxies is inconsistent with nearby spiral and starburst galaxies, but resembles those of dwarf galaxies. This is consistent with expectations for young starbursts without significant older stellar populations. This suggests that these galaxies are significantly metal-enriched, but not heavily dust-obscured, 'normal' star-forming galaxies at z > 5, showing that ALMA can detect the interstellar medium in 'typical' galaxies in the very early universe.« less
  • We present the results of a densely sampled spectroscopic survey of the SSA22 protocluster at z ≈ 3.09. Our sample with Keck/LRIS spectroscopy includes 106 Ly α emitters (LAEs) and 40 Lyman break galaxies (LBGs) at z = 3.05–3.12. These galaxies are contained within the 9′ × 9′ region in which the protocluster was discovered, which also hosts the maximum galaxy overdensity in the SSA22 region. The redshift histogram of our spectroscopic sample reveals two distinct peaks, at z = 3.069 (blue; 43 galaxies) and z = 3.095 (red; 103 galaxies). Furthermore, objects in the blue and red peaks aremore » segregated on the sky, with galaxies in the blue peak concentrating toward the western half of the field. These results suggest that the blue and red redshift peaks represent two distinct structures in physical space. Although the double-peaked redshift histogram is traced in the same manner by LBGs and LAEs, and brighter and fainter galaxies, we find that 9 out of 10 X-ray AGNs in SSA22, and all 7 spectroscopically confirmed giant Ly α “blobs,” reside in the red peak. We combine our data set with sparsely sampled spectroscopy from the literature over a significantly wider area, finding preliminary evidence that the double-peaked structure in redshift space extends beyond the region of our dense spectroscopic sampling. In order to fully characterize the three-dimensional structure, dynamics, and evolution of large-scale structure in the SSA22 overdensity, we require the measurement of large samples of LAE and LBG redshifts over a significantly wider area, as well as detailed comparisons with cosmological simulations of massive cluster formation.« less
  • We present the results of near-infrared spectroscopic observations of the K-band-selected candidate galaxies in the protocluster at z = 3.09 in the SSA22 field. We observed 67 candidates with K {sub AB} < 24 and confirmed redshifts of the 39 galaxies at 2.0 < z {sub spec} < 3.4. Of the 67 candidates, 24 are certainly protocluster members with 3.04 ≤ z {sub spec} ≤ 3.12, which are massive red galaxies that have been unidentified in previous optical observations of the SSA22 protocluster. Many distant red galaxies (J – K {sub AB} > 1.4), hyper extremely red objects (J –more » K {sub AB} > 2.1), Spitzer MIPS 24 μm sources, active galactic nuclei (AGNs) as well as the counterparts of Lyα blobs and the AzTEC/ASTE 1.1 mm sources in the SSA22 field are also found to be protocluster members. The mass of the SSA22 protocluster is estimated to be ∼2-5 × 10{sup 14} M {sub ☉}, and this system is plausibly a progenitor of the most massive clusters of galaxies in the current universe. The reddest (J – K {sub AB} ≥ 2.4) protocluster galaxies are massive galaxies with M {sub star} ∼ 10{sup 11} M {sub ☉} showing quiescent star formation activities and plausibly dominated by old stellar populations. Most of these massive quiescent galaxies host moderately luminous AGNs detected by X-ray. There are no significant differences in the [O III] λ5007/Hβ emission line ratios and [O III] λ5007 line widths and spatial extents of the protocluster galaxies from those of massive galaxies at z ∼ 2-3 in the general field.« less
  • We present results from Submillimeter Array (SMA) 860 {mu}m subarcsecond astrometry and multiwavelength observations of the brightest millimeter (S{sub 1.1mm} = 8.4 mJy) source, SSA22-AzTEC1, found near the core of the SSA22 protocluster that is traced by Ly{alpha}-emitting galaxies at z = 3.09. We identify a 860 {mu}m counterpart with a flux density of S{sub 860{sub {mu}m}} = 12.2 {+-} 2.3 mJy and absolute positional accuracy that is better than 0.''3. At the SMA position, we find radio-to-mid-infrared counterparts, whilst no object is found in Subaru optical and near-infrared deep images at wavelengths {<=}1 {mu}m (J > 25.4 in AB,more » 2{sigma}). The photometric redshift estimate, using flux densities at {>=}24 {mu}m, indicates z{sub phot} = 3.19{sup +0.26}{sub -0.35}, consistent with the protocluster redshift. We then model the near-to-mid-infrared spectral energy distribution (SED) of SSA22-AzTEC1, and find that the SED modeling requires a large extinction (A{sub V} {approx} 3.4 mag) of starlight from a stellar component with M{sub star} {approx} 10{sup 10.9} M{sub sun}, assuming z = 3.1. Additionally, we find a significant X-ray counterpart with a very hard spectrum ({Gamma}{sub eff} = -0.34{sup +0.57}{sub -0.61}), strongly suggesting that SSA22-AzTEC1 harbors a luminous active galactic nuclei (AGNs; L{sub X} {approx} 3 x 10{sup 44} erg s{sup -1}) behind a large hydrogen column (N{sub H} {approx} 10{sup 24} cm{sup -2}). The AGN, however, is responsible for only {approx}10% of the bolometric luminosity of the host galaxy, and therefore the star formation activity likely dominates the submillimeter emission. It is possible that SSA22-AzTEC1 is the first example of a protoquasar growing at the bottom of the gravitational potential underlying the SSA22 protocluster.« less
  • We study the properties of K-band-selected galaxies (K {sub AB} < 24) in the z = 3.09 SSA22 protocluster field. 430 galaxies at 2.6 < z {sub phot} < 3.6 are selected as potential protocluster members in a 112 arcmin{sup 2} area based on their photometric redshifts. We find that ≈20% of the massive galaxies with stellar masses >10{sup 11} M {sub ☉} at z {sub phot} ∼ 3.1 have colors consistent with those of quiescent galaxies with ages >0.5 Gyr. This fraction increases to ≈50% after correcting for unrelated foreground/background objects. We also find that 30% of the massivemore » galaxies are heavily reddened, dusty, star-forming galaxies. Few such quiescent galaxies at similar redshifts are seen in typical survey fields. An excess surface density of 24 μm sources at z {sub phot} ∼ 3.1 is also observed, implying the presence of dusty star-formation activity in the protocluster. Cross-correlation with the X-ray data indicates that the fraction of K-band-selected protocluster galaxies hosting active galactic nuclei (AGNs) is also high compared with the field. The sky distribution of the quiescent galaxies, the 24 μm sources, and the X-ray AGNs show clustering around a density peak of z = 3.1 Lyα emitters. A significant fraction of the massive galaxies have already become quiescent, while dusty star-formation is still active in the SSA22 protocluster. These findings indicate that we are witnessing the formation epoch of massive early-type galaxies in the centers of the predecessors to present-day rich galaxy clusters.« less