Early JWST studies reporting an unexpected abundance of massive galaxies at z ∼ 5–8 challenge galaxy formation models in the ΛCDM framework. Previous stellar mass ( M _⋆ ) estimates suffered from large uncertainties due to the lack of rest-frame near-infrared data. Using deep JWST/NIRCam and Mid-Infrared Instrument (MIRI) photometry from Public Release IMaging for Extragalactic Research, we systematically analyze massive galaxies at z ∼ 3–8, leveraging rest-frame ≳1 μ m constraints. We find MIRI is critical for robust M _⋆ measurements for massive galaxies at z > 5: excluding MIRI overestimates M _⋆ by ∼0.4 dex on average for M _⋆ > 10 ^10 M _⊙ galaxies, with no significant effects at lower masses. This reduces number densities of M _⋆ > 10 ^10 M _⊙ (10 ^10.3 M _⊙ ) galaxies by ∼36% (55%). MIRI inclusion also reduces “Little Red Dot” (LRD) contamination in massive galaxy samples, lowering the LRD fraction from ∼32% to ∼13% at M _⋆ > 10 ^10.3 M _⊙ . Assuming pure stellar origins, LRDs exhibit M _⋆ ∼ 10 ^9–10.5 M _⊙ with MIRI constraints, rarely exceeding 10 ^10.5 M _⊙ . Within standard ΛCDM, our results indicate a moderate increase in the baryon-to-star conversion efficiency ( ϵ ) toward higher redshifts and masses at z > 3. For the most massive z ∼ 8 galaxies, ϵ ∼ 0.3, compared to ϵ ≲ 0.2 for typical galaxies at z < 3. This result is consistent with models where high gas densities and short free-fall times suppress stellar feedback in massive high- z halos.

We carried out deep mapping observations of the atomic hydrogen (H I) 21 cm line emission in a field centered on the famous galaxy group Stephan's Quintet (SQ), using the Five-hundred-meter Aperture Spherical Telescope (FAST) equipped with a 19-beam receiver. The final data cube reaches an H I column density sensitivity of 5 sigma = 2.1 x 10(17) cm(-2) per 20 km s(-1) channel with an angular resolution of 4 ' 0. The discovery of a large diffuse feature of the H I emission in the outskirts of the intragroup medium of SQ was reported in a previous paper (Xu et al.). Here we present a new study of the total H I emission of SQ and the detection of several neighboring galaxies, exploiting the high sensitivity and the large sky coverage of the FAST observations. A total H I mass of M-H I = 3.48 +/- 0.35 x 10(10) M-circle dot is found for SQ, which is significantly higher than previous measurements in the literature. This indicates that, contrary to earlier claims, SQ is not H I deficient. The excessive H I gas is mainly found in the velocity ranges of 6200-6400 km s(-1) and 6800-7000 km s(-1), which were undetected in previous observations that are less sensitive than ours. Our results suggest that the "missing H I" in compact groups may be hidden in the low-density diffuse neutral gas instead of in the ionized gas.

Four ultraluminous infrared galaxies (ULIRGs) observed with JWST/NIRcam in the Cosmos Evolution Early Release Science program offer an unbiased preview of the z ∼ 2 ULIRG population. The objects were originally selected at 24 μ m and have strong polycyclic aromatic hydrocarbon emission features observed with Spitzer/Infrared Spectrometer. The four objects have similar stellar masses of ∼10 11 M ⊙ but otherwise are quite diverse. One is an isolated disk galaxy, but it has an active nucleus as shown by X-ray observations and by a bright point-source nucleus. Two others are merging pairs with mass ratios of 6–7:1. One has active nuclei in both components, while the other has only one active nucleus: the one in the less-massive neighbor, not the ULIRG. The fourth object is clumpy and irregular and is probably a merger, but there is no sign of an active nucleus. The intrinsic spectral energy distributions for the four active galactic nuclei in these systems are typical of type-2 QSOs. This study is consistent with the idea that even if internal processes can produce large luminosities at z ∼ 2, galaxy merging may still be necessary for the most luminous objects. The diversity of these four initial examples suggests that large samples will be needed to understand the z ∼ 2 ULIRG population.

We present the results of an integral field spectroscopy survey of a sample of dusty (ultra) luminous infrared galaxies (U/LIRGs) at 2 < z < 2.5 using KMOS on the Very Large Telescope. The sample has been drawn from Herschel deep field surveys and benefits from ancillary multiwavelength data. Our goal is to investigate the physical characteristics, kinematics, and the drivers of star formation in the galaxies whose contribution dominates the peak of the cosmic star formation density. Two-thirds of the sample are main-sequence galaxies in contrast to the starburst nature of local U/LIRGs. Our kinematic study, unique in its focus on z similar to 2 dusty star-forming galaxies, uses the H alpha emission line to find that similar to 40 per cent appear to be isolated discs based on the ratio of rotational velocity to the velocity dispersion, suggesting steady-state mechanisms are sufficient to power the large star formation rates (SFRs). The ratio of obscured to unobscured star formation indicates the sample of galaxies experiences less dust obscuration compared to intermediate and local counterparts, while also hosting cooler dust than local U/LIRGs. In addition to H alpha we detect [N ii] 6583 angstrom in our targets and show the gas-phase metallicities do not exhibit the metal deficiency of local U/LIRGs. These results indicate that, despite their extreme IR luminosity, the underlying mechanisms driving the massive SFRs found at cosmic noon are due to scaled up disc galaxies as opposed to mergers.

The extreme infrared (IR) luminosity of local luminous and ultraluminous IR galaxies (11/LIRGs; 11 < log LIR/LE:, < 12 and log LIR /L.> 12., respectively) is mainly powered by star formation processes triggered by mergers or interactions. While INLIRGs are rare locally, at z > 1, they become more common, dominate the star formation rate (SFR) density, and a fraction of them are found to be normal disc galaxies. Therefore, there must be an evolution of the mechanism triggering these intense starbursts with redshift. To investigate this evolution, we present new optical swit,r integral field spectroscopic H cx + [N n] observations of a sample of nine intermediate-z (0.2 < z < 0.4) INEIRG systems selected from Herschel 250 p.m observations. The main results are the following: (a) the ratios between the velocity dispersion and the rotation curve amplitude indicate that 10-25 per cent (1-2 of 8) might be compatible with being isolated discs, while the remaining objects are interactinghnerging systems; (b) the ratio between un-obscured and obscured SFR traced by H cz and LIR, respectively, is similar in both local and these intermediate-z Ll/LIRGs; and (c) the ratio between 250 p.im and the total IR luminosities of these intermediate-z INEIRGs is-higher than that of local INLIRGs with the same LIR, This indicates a reduced dust temperature in these intermediate-z INLIRGs. This, together with their already measured enhanced molecular gas content, suggests that the interstellar medium conditions are different in our sample of intermediate-z galaxies when compared to local II/LIRGs.

We present millimetre dust emission measurements of two Lyman Break Galaxies at z~3 and construct for the first time fully sampled infrared spectral energy distributions (SEDs), from mid-IR to the Rayleigh-Jeans tail, of individually detected, unlensed, UV-selected, main sequence (MS) galaxies at $z=3$. The SED modelling of the two sources confirms previous findings, based on stacked ensembles, of an increasing mean radiation field with redshift, consistent with a rapidly decreasing gas metallicity in z > 2 galaxies. Complementing our study with CO[3-2] emission line observations, we measure the molecular gas mass (M_H2) reservoir of the systems using three independent approaches: 1) CO line observations, 2) the dust to gas mass ratio vs metallicity relation and 3) a single band, dust emission flux on the Rayleigh-Jeans side of the SED. All techniques return consistent M_H2 estimates within a factor of ~2 or less, yielding gas depletion time-scales (tau_dep ~ 0.35 Gyrs) and gas-to-stellar mass ratios (M_H2/M* ~ 0.5-1) for our z~3 massive MS galaxies. The overall properties of our galaxies are consistent with trends and relations established at lower redshifts, extending the apparent uniformity of star-forming galaxies over the last 11.5 billion years.

We present millimetre dust emission measurements of two Lyman Break Galaxies at z~3 and construct for the first time fully sampled infrared spectral energy distributions (SEDs), from mid-IR to the Rayleigh-Jeans tail, of individually detected, unlensed, UV-selected, main sequence (MS) galaxies at $z=3$. The SED modelling of the two sources confirms previous findings, based on stacked ensembles, of an increasing mean radiation field with redshift, consistent with a rapidly decreasing gas metallicity in z > 2 galaxies. Complementing our study with CO[3-2] emission line observations, we measure the molecular gas mass (M_H2) reservoir of the systems using three independent approaches: 1) CO line observations, 2) the dust to gas mass ratio vs metallicity relation and 3) a single band, dust emission flux on the Rayleigh-Jeans side of the SED. All techniques return consistent M_H2 estimates within a factor of ~2 or less, yielding gas depletion time-scales (tau_dep ~ 0.35 Gyrs) and gas-to-stellar mass ratios (M_H2/M* ~ 0.5-1) for our z~3 massive MS galaxies. The overall properties of our galaxies are consistent with trends and relations established at lower redshifts, extending the apparent uniformity of star-forming galaxies over the last 11.5 billion years.

We introduce a new color selection technique to identify high-redshift, massive galaxies that are systematically missed by Lyman-break selection. The new selection is based on the H-160 (H) and Infrared Array Camera (IRAC) 4.5 mu m bands, specifically H - [4.5] > 2.25 mag. These galaxies, called "HIEROs," include two major populations that can be separated with an additional J - H color. The populations are massive and dusty starforming galaxies at z > 3 (JH - blue) and extremely dusty galaxies at z less than or similar to 3 (JH - red). The 350 arcmin(2) of the GOODS-North and GOODS-South fields with the deepest Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) near-infrared and IRAC data contain as many as 285 HIEROs down to [4.5] < 24 mag. Inclusion of the most extreme HIEROs, not even detected in the H band, makes this selection particularly complete for the identification of massive high-redshift galaxies. We focus here primarily on JH - blue (z > 3) HIEROs, which have a median photometric redshift < z > similar to 4.4 and stellar mass M-* 10(10.6) M-circle dot and are much fainter in the rest-frame UV than similarly massive Lyman-break galaxies (LBGs). Their star formation rates (SFRs), derived from their stacked infrared spectral energy distributions (SEDs), reach similar to 240 M-circle dot yr(-1), leading to a specific SFR, sSFR equivalent to SFR/M-* similar to 4.2 Gyr(-1), suggesting that the sSFRs for massive galaxies continue to grow at z > 2 but at a lower growth rate than from z = 0 to z = 2. With a median half-light radius of 2 kpc, including similar to 20% as compact as quiescent (QS) galaxies at similar redshifts, JH - blue HIEROs represent perfect star-forming progenitors of the most massive (M-* greater than or similar to 10(11.2) M-circle dot) compact QS galaxies at z similar to 3 and have the right number density. HIEROs make up similar to 60% of all galaxies with M-* > 10(10.5) M-circle dot identified at z > 3 from their photometric redshifts. This is five times more than LBGs with nearly no overlap between the two populations. While HIEROs make up 15%-25% of the total SFR density at z similar to 4-5, they completely dominate the SFR density taking place in M-* 10(10.5) M-circle dot galaxies, and HIEROs are therefore crucial to understanding the very early phase of massive galaxy formation.

The deep, wide-area (similar to 800-900 arcmin(2)) near-infrared/WFC3/IR + Spitzer/IRAC observations over the CANDELS fields have been a remarkable resource for constraining the bright end of high-redshift UV luminosity functions. However, the lack of Hubble Space Telescope (HST) 1.05 mu m observations over the CANDELS fields has made it difficult to identify z similar to 9-10 sources robustly, since such data are needed to confirm the presence of an abrupt Lyman break at 1.2 mu m. Here, we report on the successful identification of many such z similar to 9-10 sources from a new HST program (z9-CANDELS) that targets the highest-probability z similar to 9-10 galaxy candidates with observations at 1.05 mu m, to search for a robust Lyman-break at 1.2 mu m. The potential z similar to 9-10 candidates were preselected from the full HST, Spitzer/IRAC S-CANDELS observations, and the deepest-available ground-based optical+near-infrared observations (CFHTLS-DEEP+HUGS+UltraVISTA+ZFOURGE). We identified 15 credible z similar to 9-10 galaxies over the CANDELS fields. Nine of these galaxies lie at z similar to 9 and five are new identifications. Our targeted follow-up strategy has proven to be very efficient in making use of scarce HST time to secure a reliable sample of z similar to 9-10 galaxies. Through extensive simulations, we replicate the selection process for our sample (both the preselection and follow-up) and use it to improve current estimates for the volume density of bright z similar to 9 and z similar to 10 galaxies. The volume densities we find are 5(-2)(+3)x and 8(-3)(+9)x lower, respectively, than those found at z similar to 8. When compared with the best-fit evolution (i.e., d log(10) rho(UV)/dz = -0.29 +/- 0.02) in the UV luminosity densities from z similar to 8 to z similar to 4 integrated to 0.3L(z=3)* (-20 mag), these luminosity densities are 2.6(-0.9)(+1.5)x and 2.2(-1.1)(+2.0) lower, respectively, than the extrapolated trends. Our new results are broadly consistent with the "accelerated evolution" scenario at z > 8, consistent with that seen in many models.

We explore the dependence of the incidence of moderate-luminosity ( L 0 . 5 − 8 keV = 10 41 . 9 − 43 . 7 erg s − 1 ) active galactic nuclei (AGNs) and the distribution of their accretion rates on host color at 0 . 5 < z < 2 . 5. Based on the deepest X-ray and UV-to-far-infrared data in the two The Great Observatories Origins Deep Survey (GOODS) fields, we identify 221 AGNs within a mass-complete parent galaxy sample down to M ∗ > 10 10 M (cid:12) . We use extinction-corrected rest-frame U − V colors to divide both AGN hosts and non-AGN galaxies into red sequence (red), green valley (green), and blue cloud (blue) populations. We find that the fraction of galaxies hosting an AGN at fixed X-ray luminosity increases with stellar mass and redshift for all the three galaxy populations, independent of their colors. However, both the AGN fraction at fixed stellar mass and its evolution with redshift are clearly dependent on host colors. Most notably, red galaxies have the lowest AGN fraction ( ∼ 5%) at z ∼ 1 yet with most rapid evolution with redshift, increasing by a factor of ∼ 5 (24%) at z ∼ 2. Green galaxies exhibit the highest AGN fraction across all redshifts, which is most pronounced at z ∼ 2 with more than half of them hosting an AGN at M ∗ > 10 10 . 6 M (cid:12) . Together with the high AGN fraction in red galaxies at z ∼ 2, this indicates that (X-ray) AGNs could be important in both transforming (quenching) star-forming galaxies into quiescent ones and subsequently maintaining their quiescence at high redshift. Furthermore, consistent with previous studies at lower redshifts, we show that the probability of hosting an AGN for the total galaxy population can be characterized by a universal Eddington ratio (as approximated by L X / M ∗ ) distribution ( p ( λ Edd ) ∼ λ − 0 . 4 Edd ), which is independent on host mass. Yet consistent with their di ff erent AGN fractions, galaxies with di ff erent colors appear to also have di ff erent p ( λ Edd ) with red galaxies exhibiting more rapid redshift evolution compared with that for green and blue galaxies. Evidence for a steeper power-law distribution of p ( λ Edd ) in red galaxies ( p ( λ Edd ) ∼ λ − 0 . 6 Edd ) is also presented, though larger samples are needed to confirm. These results suggest that the AGN accretion or the growth of supermassive black holes is related to their host properties, and may also influence their hosts in a di ff erent mode dependent on the host color.

One of the most challenging aspects of studying galaxies in the z>~7 universe is the infrequent confirmation of their redshifts through spectroscopy, a phenomenon thought to occur from the increasing opacity of the intergalactic medium to Lya photons at z>6.5. The resulting redshift uncertainties inhibit the efficient search for [C II] in z~7 galaxies with sub-mm instruments such as ALMA, given their limited scan speed for faint lines. One means by which to improve the precision of the inferred redshifts is to exploit the potential impact of strong nebular emission lines on the colors of z~4-8 galaxies as observed by Spitzer/IRAC. At z~6.8, galaxies exhibit IRAC colors as blue as [3.6]-[4.5] ~-1, likely due to the contribution of [O III]+Hb to the 3.6 mum flux combined with the absence of line contamination in the 4.5 mum band. In this paper we explore the use of extremely blue [3.6]-[4.5] colors to identify galaxies in the narrow redshift window z~6.6-6.9. When combined with an I-dropout criterion, we demonstrate that we can plausibly select a relatively clean sample of z~6.8 galaxies. Through a systematic application of this selection technique to our catalogs from all five CANDELS fields, we identify 20 probable z~6.6-6.9 galaxies. We estimate that our criteria select the ~50% strongest line emitters at z~6.8 and from the IRAC colors we estimate a typical [O III]+Hb rest-frame equivalent width of 1085A for this sample. The small redshift uncertainties on our sample make it particularly well suited for follow-up studies with facilities such as ALMA.

We present the results of deep Chandra imaging of the central region of the Extended Groth Strip, the AEGIS-X Deep (AEGIS-XD) survey. When combined with previous Chandra observations of a wider area of the strip, AEGIS-X Wide (AEGIS-XW), these provide data to a nominal exposure depth of 800 ks in the three central ACIS-I fields, a region of approximately 0.29 deg(2). This is currently the third deepest X-ray survey in existence; a factor similar to 2-3 shallower than the Chandra Deep Fields (CDFs), but over an area similar to 3 times greater than each CDF. We present a catalog of 937 point sources detected in the deep Chandra observations, along with identifications of our X-ray sources from deep ground-based, Spitzer, GALEX, and Hubble Space Telescope imaging. Using a likelihood ratio analysis, we associate multiband counterparts for 929/937 of our X-ray sources, with an estimated 95% reliability, making the identification completeness approximately 94% in a statistical sense. Reliable spectroscopic redshifts for 353 of our X-ray sources are available predominantly from Keck (DEEP2/3) and MMT Hectospec, so the current spectroscopic completeness is similar to 38%. For the remainder of the X-ray sources, we compute photometric redshifts based on multiband photometry in up to 35 bands from the UV to mid-IR. Particular attention is given to the fact that the vast majority the X-ray sources are active galactic nuclei and require hybrid templates. Our photometric redshifts have mean accuracy of sigma = 0.04 and an outlier fraction of approximately 5%, reaching sigma = 0.03 with less than 4% outliers in the area covered by CANDELS. The X-ray, multiwavelength photometry, and redshift catalogs are made publicly available.

We present Herschel far-IR photometry and spectroscopy as well as ground-based CO observations of an intermediate redshift (0.21 ⩽ z ⩽ 0.88) sample of Herschel-selected (ultra)-luminous infrared galaxies (LIR > 1011.5 L☉). With these measurements, we trace the dust continuum, far-IR atomic line emission, in particular [C ii] 157.7 μm, as well as the molecular gas of z ∼ 0.3 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) and perform a detailed investigation of the interstellar medium of the population. We find that the majority of Herschel-selected intermediate redshift (U)LIRGs have LC ii/LFIR ratios that are a factor of about 10 higher than that of local ULIRGs and comparable to that of local normal and high-z star-forming galaxies. Using our sample to bridge local and high-z [C ii] observations, we find that the majority of galaxies at all redshifts and all luminosities follow an LC ii−LFIR relation with a slope of unity, from which local ULIRGs and high-z active-galactic-nucleus-dominated sources are clear outliers. We also confirm that the strong anti-correlation between the LC ii/LFIR ratio and the far-IR color L60/L100 observed in the local universe holds over a broad range of redshifts and luminosities, in the sense that warmer sources exhibit lower LC ii/LFIR at any epoch. Intermediate redshift ULIRGs are also characterized by large molecular gas reservoirs and by lower star formation efficiencies compared to that of local ULIRGs. The high LC ii/LFIR ratios, the moderate star formation efficiencies (LIR/ or LIR/), and the relatively low dust temperatures of our sample (which are also common characteristics of high-z star-forming galaxies with ULIRG-like luminosities) indicate that the evolution of the physical properties of (U)LIRGs between the present day and z > 1 is already significant by z ∼ 0.3.

We present the discovery of four surprisingly bright (H160 ∼ 26–27 mag AB) galaxy candidates at z ∼ 9–10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z ∼ 10 galaxy candidates that are known, just ∼500 Myr after the big bang. Two similarly bright sources are also detected in a reanalysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5σ–6.2σ in the very deep Spitzer/IRAC 4.5 μm data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z = 10.2 ± 0.4) is robustly detected also at 3.6 μm (6.9σ), revealing a flat UV spectral energy distribution with a slope β = −2.0 ± 0.2, consistent with demonstrated trends with luminosity at high redshift. Thorough testing and use of grism data excludes known low-redshift contamination at high significance, including single emission-line sources, but as-yet unknown low redshift sources could provide an alternative solution given the surprising luminosity of these candidates. Finding such bright galaxies at z  ∼  9–10 suggests that the luminosity function for luminous galaxies might evolve in a complex way at z > 8. The cosmic star formation rate density still shows, however, an order-of-magnitude increase from z ∼ 10 to z ∼ 8 since the dominant contribution comes from low-luminosity sources. Based on the IRAC detections, we derive galaxy stellar masses at z ∼ 10, finding that these luminous objects are typically 109 M☉. This allows for a first estimate of the cosmic stellar mass density at z ∼ 10 resulting in M☉ Mpc−3 for galaxies brighter than MUV ∼ −18. The remarkable brightness, and hence luminosity, of these z ∼ 9–10 candidates will enable deep spectroscopy to determine their redshift and nature, and highlights the opportunity for the James Webb Space Telescope to map the buildup of galaxies at redshifts much earlier than z ∼ 10.

We report the first results from a spectroscopic survey of the [C II] 158 mu m line from a sample of intermediate redshift (0.2 < z < 0.8) (ultra)-luminous infrared galaxies, (U) LIRGs (L-IR > 10(11.5) L-circle dot), using the Spectral and Photometric Imaging REceiver-Fourier Transform Spectrometer on board the Herschel Space Observatory. This is the first survey of [C II] emission, an important tracer of star formation, at a redshift range where the star formation rate density of the universe increases rapidly. We detect strong [C II] 158 mu m line emission from over 80% of the sample. We find that the [C II] line is luminous, in the range (0.8-4) x 10(-3) of the far-infrared continuum luminosity of our sources, and appears to arise from photodissociation regions on the surface of molecular clouds. The L-[C II]/L-IR ratio in our intermediate redshift (U) LIRGs is on average similar to 10 times larger than that of local ULIRGs. Furthermore, we find that the L-[C II]/L-IR and L-[C II]/LCO(1-0) ratios in our sample are similar to those of local normal galaxies and high-z star-forming galaxies. ULIRGs at z similar to 0.5 show many similarities to the properties of local normal and high-z star-forming galaxies. Our findings strongly suggest that rapid evolution in the properties of the star-forming regions of (U) LIRGs is likely to have occurred in the last 5 billion years.

We present the results of a combined galaxy population analysis for the host galaxies of active galactic nuclei (AGN) identified at 0 < z < 1.4 within the SDSS, Bootes and DEEP2 surveys. We identified AGN in a uniform and unbiased manner at X-ray, infrared and radio wavelengths. Supermassive black holes undergoing radiatively-efficient accretion (detected as X-ray and/or infrared AGN) appear to be hosted in a separate and distinct galaxy population than AGN undergoing powerful mechanically dominated accretion (radio AGN). Consistent with some previous studies, radiatively efficient AGN appear to be preferentially hosted in modest star-forming galaxies, with little dependence on AGN or galaxy luminosity. AGN exhibiting radio-emitting jets due to mechanically-dominated accretion are almost exclusively observed in massive, passive galaxies. Crucially, we now provide strong evidence that the observed host-galaxy trends are independent of redshift. In particular, these different accretion-mode AGN have remained as separate galaxy populations throughout the last 9 Gyr. Furthermore, it appears that galaxies hosting AGN have evolved along the same path as galaxies that are not hosting AGN with little evidence for distinctly separate evolution.

We present a study of the infrared properties for a sample of seven spectroscopically confirmed submillimeter galaxies (SMGs) at z > 4.0. By combining ground-based near-infrared, Spitzer IRAC and MIPS, Herschel SPIRE, and ground-based submillimeter/millimeter photometry, we construct their spectral energy distributions (SEDs) and a composite model to fit the SEDs. The model includes a stellar emission component at lambda(rest) < 3.5 mu m ot dust component peaking at lambda(rest) similar to 5 mu m and cold dust component which becomes significant for lambda(rest) > 50 mu m. Six objects in the sample are detected at 250 and 350 mu m. The dust temperatures for the sources in this sample are in the range of 40-80 K, and their LFIR similar to 10(13) L circle dot qualifies them as hyper-luminous infrared galaxies. The mean FIR-radio index for this sample is around q = 2.2 indicating no radio excess in their radio emission. Most sources in the sample have 24 mu m detections corresponding to a rest-frame 4.5 mu m luminosity of Log(10)(L-4.5/L circle dot) = 11 similar to 11.5. Their L4.5/L-FIR ratios are very similar to those of starburst-dominated SMGs at z similar to 2. The LCO -LFIR relation for this sample is consistent with that determined for local ULIRGs and SMGs at z similar to 2. We conclude that SMGs at z > 4 are hotter and more luminous in the FIR but otherwise very similar to those at z similar to 2. None of these sources show any sign of the strong QSO phase being triggered.

deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with redshift z > 6.5 detects a near-infrared emission line from only a single galaxy; this line is likely to be Lyman α emission at a wavelength of 1.0343 μm, placing this galaxy at z = 7.51.