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We report a massive quiescent galaxy at spectroscopically confirmed at a protocluster in the SSA22 field by detecting the Balmer and Ca ii absorption features with the multi-object spectrometer for infrared exploration on the Keck I telescope. This is the most distant quiescent galaxy confirmed in a protocluster to date. We fit the optical to mid-infrared photometry and spectrum simultaneously with spectral energy distribution (SED) models of parametric and nonparametric star formation histories (SFHs). Both models fit the observed SED well and confirm that this object is a massive quiescent galaxy with a stellar mass of and , and a star formation rate of SFR/M⊙ yr−1 < 0.3 and for parametric and nonparametric models, respectively. The SFH from the former modeling is described as an instantaneous starburst whereas that of the latter modeling is longer-lived, but both models agree with a sudden quenching of the star formation at ∼0.6 Gyr ago. This massive quiescent galaxy is confirmed in an extremely dense group of galaxies predicted as a progenitor of a brightest cluster galaxy formed via multiple mergers in cosmological numerical simulations. We discover three new plausible [O iii ]λ5007 emitters at 3.0791 ≤ zspec ≤ 3.0833 serendipitously detected around the target. Two of them just between the target and its nearest massive galaxy are possible evidence of their interactions. They suggest the future great size and stellar mass evolution of this massive quiescent galaxy via mergers. [ABSTRACT FROM AUTHOR]

We present observations of a giant Lyα blob (LAB) in the SSA22 protocluster at z = 3.1, SSA22-LAB1, taken with the Atacama Large Millimeter/submillimeter Array. Dust continuum, along with [C ii ] 158 μm and CO(4–3) line emission have been detected in LAB1, showing complex morphology and kinematics across a ∼100 kpc central region. Seven galaxies at z = 3.0987–3.1016 in the surroundings are identified in [C ii ] and dust continuum emission, with two of them potential companions or tidal structures associated with the most massive galaxies. Spatially resolved [C ii ] and infrared luminosity ratios for the widely distributed media (L[Cɪɪ]/LIR ≈ 10−2−10−3) suggest that the observed extended interstellar media are likely to have originated from star formation activity and the contribution from shocked gas is probably not dominant. LAB1 is found to harbor a total molecular gas mass Mmol = (8.7 ± 2.0) × 1010M⊙, concentrated in the core region of the Lyα-emitting area. While (primarily obscured) star formation activity in the LAB1 core is one of the most plausible power sources for the Lyα emission, multiple major mergers found in the core may also play a role in making LAB1 exceptionally bright and extended in Lyα as a result of cooling radiation induced by gravitational interactions. [ABSTRACT FROM AUTHOR]

We present a detailed investigation of millimeter-wave line emitters ALMA J010748.3-173028 (ALMA-J0107a) and ALMA J010747.0-173010 (ALMA-J0107b), which were serendipitously uncovered in the background of the nearby galaxy VV 114 with spectral scan observations at λ = 2–3 mm. Via Atacama Large Millimeter/submillimeter Array (ALMA) detection of CO(4–3), CO(3–2), and [C i ](1–0) lines for both sources, their spectroscopic redshifts are unambiguously determined to be z = 2.4666 ± 0.0002 and z = 2.3100 ± 0.0002, respectively. We obtain the apparent molecular gas masses Mgas of these two line emitters from [C i ] line fluxes as (11.2 ± 3.1) × 1010M⊙ and (4.2 ± 1.2) × 1010M⊙, respectively. The observed CO(4–3) velocity field of ALMA-J0107a exhibits a clear velocity gradient across the CO disk, and we find that ALMA-J0107a is characterized by an inclined rotating disk with a significant turbulence, that is, a deprojected maximum rotation velocity to velocity dispersion ratio of 1.3 ± 0.3. We find that the dynamical mass of ALMA-J0107a within the CO-emitting disk computed from the derived kinetic parameters, (1.1 ± 0.2) × 1010M⊙, is an order of magnitude smaller than the molecular gas mass derived from dust continuum emission, (3.2 ± 1.6) × 1011M⊙. We suggest this source is magnified by a gravitational lens with a magnification of μ ≳ 10, which is consistent with the measured offset from the empirical correlation between CO-line luminosity and width. [ABSTRACT FROM AUTHOR]

We present results of the cross-correlation Lyα intensity mapping with Subaru/Hyper Suprime-Cam (HSC) ultra-deep narrowband images and Lyα emitters (LAEs) at z = 5.7 and 6.6 in a total area of 4 deg2. Although an overwhelming amount of data quality controls have been performed for the narrowband images, we further conduct extensive analyses evaluating systematics of large-scale point-spread function wings, sky subtractions, and unknown errors based on physically uncorrelated signals and sources found in real HSC images and object catalogs, respectively. Removing the systematics, we carefully calculate cross-correlations between Lyα intensity of the narrowband images and the LAEs. We tentatively identify very diffuse Lyα emission with the ≃3σ (≃2σ) significance at ≳100 comoving kiloparsecs (ckpc) far from the LAEs at z = 5.7 (6.6), around and probably even beyond a virial radius of star-forming galaxies with Mh ∼ 1011M⊙. The diffuse Lyα emission possibly extends up to 1000 ckpc with the surface brightness of 10−20–10−19 erg s−1 cm−2 arcsec−2. We confirm that the small-scale (<150 ckpc) Lyα radial profiles of LAEs are consistent with those obtained by recent Multi-Unit Spectroscopic Explorer observations. Comparisons with numerical simulations suggest that the large-scale (∼150–1000 ckpc) Lyα emission are not explained by unresolved faint neighboring galaxies including satellites, but by a combination of Lyα photons emitted from the central LAE and other unknown sources, such as cold-gas streams and galactic outflow. We find no evolution in the Lyα radial profiles of our LAEs from z = 5.7 to 6.6, where theoretical models predict a flattening of the profile slope made by cosmic reionization, albeit with our moderately large observational errors. [ABSTRACT FROM AUTHOR]

We present our new Atacama Large Millimeter/Submillimeter Array (ALMA) observations targeting [O iii ]88 μm, [C ii ]158 μm, [N ii ]122 μm, and dust-continuum emission for three Lyman break galaxies at z = 6.0293–6.2037, identified in the Subaru/Hyper Suprime-Cam survey. We clearly detect [O iii ] and [C ii ] lines from all of the galaxies at 4.3–11.8σ levels, and identify multi-band dust-continuum emission in two of the three galaxies, allowing us to estimate infrared luminosities and dust temperatures simultaneously. In conjunction with previous ALMA observations for six galaxies at z > 6, we confirm that all the nine z = 6–9 galaxies have high [O iii ]/[C ii ] ratios of , ∼10 times higher than z ∼ 0 galaxies. We also find a positive correlation between the [O iii ]/[C ii ] ratio and the Lyα equivalent width (EW) at the ∼90% significance level. We carefully investigate physical origins of the high [O iii ]/[C ii ] ratios at z = 6–9 using Cloudy, and find that high density of the interstellar medium, low C/O abundance ratio, and the cosmic microwave background attenuation are responsible to only a part of the z = 6–9 galaxies. Instead, the observed high [O iii ]/[C ii ] ratios are explained by 10–100 times higher ionization parameters or low photodissociation region (PDR) covering fractions of 0%–10%, both of which are consistent with our [N ii ] observations. The latter scenario can be reproduced with a density-bounded nebula with PDR deficit, which would enhance the Lyα, Lyman continuum, and ionizing photons escape from galaxies, consistent with the [O iii ]/[C ii ]-Lyα EW correlation we find. [ABSTRACT FROM AUTHOR]

We present an IGM H i tomographic map in a survey volume of (cMpc3) centered at MAMMOTH-1 nebula and three neighboring quasars at z = 2.3. The MAMMOTH-1 nebula is an enormous Lyα nebula (ELAN), hosted by a type-II quasar dubbed MAMMOTH1-QSO, that extends over cMpc with no clear physical origin. Here we investigate the H i -gas distribution around MAMMOTH1-QSO with the ELAN and three neighboring type-I quasars, making the IGM H i tomographic map with a spatial resolution of 2.6 h−1 cMpc. Our H i tomographic map is reconstructed with H i Lyα forest absorption of bright background objects at z = 2.4–2.9: one eBOSS quasar and 16 Keck/LRIS galaxy spectra. We estimate the radial profile of H i overdensity for MAMMOTH1-QSO, and find that MAMMOTH1-QSO resides in a volume with fairly weak H i absorption. This suggests that MAMMOTH1-QSO may have a proximity zone where quasar illuminates and photoionizes the surrounding H i gas and suppresses H i absorption, and that the ELAN is probably a photoionized cloud embedded in the cosmic web. The H i radial profile of MAMMOTH1-QSO is very similar to those of three neighboring type-I quasars at z = 2.3, which is compatible with the AGN unification model. We compare the distributions of the H i absorption and star-forming galaxies in our survey volume, and identify a spatial offset between density peaks of star-forming galaxies and H i gas. This segregation may suggest anisotropic UV background radiation created by star-forming galaxy density fluctuations. [ABSTRACT FROM AUTHOR]

The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large-scale structure of the universe at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a cold-dark-matter- (CDM-) dominated universe predict that the IGM is distributed in a cosmic web of filaments and that galaxies should form along and at the intersections of these filaments. While observations of QSO absorption lines and the large-scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web of IGM has never been confirmed by direct imaging. Here we report our observation of the Lyα blob 2 (LAB2) in SSA22 with the Cosmic Web Imager (CWI). This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hr of total on- and off-source exposure, CWI has revealed that LAB2 has extended Lyα emission that is organized into azimuthal zones consistent with filaments. We perform numerous tests with simulations and the data to secure the robustness of this result, which relies on data with modest signal-to-noise ratios. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles characteristic of optically thick Lyα emission. The flux is 10-20 times brighter than expected for the average emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using simple emission models, we infer a baryon mass in the filaments of at least 1-4 × 1011M☼, and the dark halo mass is at least 2 × 1012M☼. The spatial-kinematic morphology is more consistent with inflow from the cosmic web than outflow from LAB2, although an outflow feature maybe present at one azimuth. LAB2 and the surrounding gas have significant and coaligned angular momentum, strengthening the case for their association. [ABSTRACT FROM AUTHOR]

In order to constrain the bolometric luminosities, dust properties, and molecular gas content of giant Lyα nebulae, the so-called Lyα blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z ~ 3: an Lyα blob discovered by its strong Spitzer Multiband Infrared Photometer 24 µm detection (LABd05) and the Steidel blob 1 (SSA22-LAB01). We find that the spectral energy distribution of LABd05 is well described by an active-galactic-nucleus--starburst composite template with LFIR = (4.0 ± 0.5) x 1012 L⊙, comparable to high-z submillimeter galaxies and ultraluminous infrared galaxies. New Large APEX Bolometer Camera 870 µm measurements rule out the reported Submillimeter Common-User Bolometer Array detection of the SSA22-LAB01 (S850 µm = 16.8 mJy) at the >4σ level. Consistent with this, ultradeep Plateau de Bure Interferometer observations with ~2" spatial resolution also fail to detect any 1.2 mm continuum source down to ≈0.45 mJy beam-1 (3σ). Combined with the existing (sub)millimeter observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of SvΔV ≲ 0.25-1.0 Jy km s-1, indicating a modest molecular gas reservoir, M(H2) < (1-3) x 1010 M⊙. The non-detections exclude, with high significance (12σ), the previous tentative detection of a CO J = 4-3 line in the SSA22-LAB01. The increased sensitivity afforded by the Atacama Large Millimeter/submillimeter Array will be critical in studying molecular gas and dust in these interesting systems. [ABSTRACT FROM AUTHOR]

We present Keck spectroscopic observations of z > 6 Lyman-break galaxy (LBG) candidates in the Subaru Deep Field (SDF). The candidates were selected as i'-dropout objects down to z' = 27 AB magnitudes from an ultra-deep SDF z'-band image. With the Keck spectroscopy we identified 19 LBGs with prominent Lyα emission lines at 6 ≤ z ≤ 6.4. The median value of the Lyα rest-frame equivalent widths (EWs) is ~50Å, with four EWs > 100 Å. This well-defined spectroscopic sample spans a UV-continuum luminosity range of -21.8 ≤ MUV ≤ -19.5 (0.6 ~ 5 L*UV) and a Lyα luminosity range of (0.3-3) x 1043 erg s-1 (0.3-3 L*Lyα). We derive the UV and Lyα luminosity functions (LFs) from our sample at (z) ~ 6.2 after we correct for sample incompleteness. We find that our measurement of the UV LF is consistent with the results of previous studies based on photometric LBG samples at 5 < z < 7. Our Lyα, LF is also generally in agreement with the results of Lyα-emitter surveys at z ~ 5.7 and 6.6. This study shows that deep spectroscopic observations of LBGs can provide unique constraints on both the UV and Lyα LFs at z > 6. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 KAB < 24 and confirmed redshifts of the 39 galaxies at 2.0 < zspec < 3.4. Of the 67 candidates, 24 are certainly protocluster members with 3.04 ⩽ zspec ⩽ 3.12, which are massive red galaxies that have been unidentified in previous optical observations of the SSA22 protocluster. Many distant red galaxies (J – KAB > 1.4), hyper extremely red objects (J – KAB > 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 × 1014M☼, and this system is plausibly a progenitor of the most massive clusters of galaxies in the current universe. The reddest (J – KAB ⩾ 2.4) protocluster galaxies are massive galaxies with Mstar ∼ 1011M☼ 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. [ABSTRACT FROM AUTHOR]

We have identified a very interesting Lyα emitter (LAE), whose Lyα emission line has an extremely large observed equivalent width of EW0 = 436+422– 149 Å, which corresponds to an extraordinarily large intrinsic rest-frame equivalent width of EWint0 = 872+844– 298 Å after the average intergalactic absorption correction. The object was spectroscopically confirmed to be a real LAE by its apparent asymmetric Lyα line profile detected at z = 6.538. The continuum emission of the object was definitely detected in our deep z′-band image; thus, its EW0 was reliably determined. Follow-up deep near-infrared spectroscopy revealed emission lines of neither He II λ1640 as an apparent signature of Population III (Pop III) nor C IV λ1549 as proof of an active nucleus. No detection of the short-lived He II λ1640 line is not necessarily inconsistent with the interpretation that the underlying stellar population of the object is dominated by Pop III. We found that the observed extremely large EW0 of the Lyα emission and the upper limit on the EW0 of the He II λ1640 emission can be explained by population synthesis models favoring a very young age less than 2-4 Myr and massive metal-poor (Z < 10–5) or even metal-free stars. The observed large EW0 of Lyα is insufficiently explained by Population I/II synthesis models with Z ⩾ 10–3. However, we cannot conclusively rule out the possibility that this object is composed of a normal stellar population with a clumpy dust distribution, which could enhance the Lyα EW0, though its significance is still unclear. [ABSTRACT FROM AUTHOR]

Detailed analysis of the substructure of Lyα nebulae can put important constraints on the physical mechanisms at work and the properties of galaxies forming within them. Using high-resolution Hubble Space Telescope (HST) imaging of a Lyα nebula at z ≈ 2.656, we have taken a census of the compact galaxies in the vicinity, used optical/near-infrared colors to select system members, and put constraints on the morphology of the spatially extended emission. The system is characterized by (1) a population of compact, low-luminosity (∼0.1 L*) sources—17 primarily young, small (Re ≈ 1-2 kpc), disky galaxies including an obscured active galactic nucleus—that are all substantially offset (≳20 kpc) from the line-emitting nebula; (2) the lack of a central galaxy at or near the peak of the Lyα emission; and (3) several nearly coincident, spatially extended emission components—Lyα, He II, and UV continuum—that are extremely smooth. These morphological findings are difficult to reconcile with theoretical models that invoke outflows, cold flows, or resonant scattering, suggesting that while all of these physical phenomena may be occurring, they are not sufficient to explain the powering and large extent of Lyα nebulae. In addition, although the compact galaxies within the system are irrelevant as power sources, the region is significantly overdense relative to the field galaxy population (by at least a factor of four). These observations provide the first estimate of the luminosity function of galaxies within an individual Lyα nebula system and suggest that large Lyα nebulae may be the seeds of galaxy groups or low-mass clusters. [ABSTRACT FROM AUTHOR]