The
Planck
satellite has identified more than 2000 protocluster candidates with extreme star formation rates (SFRs). Here, we present the spectroscopic identification of a
Planck
-selected ...protocluster located in the Cosmos field, PHz G237.01+42.50. PHz G237.01+42.50 contains a galaxy overdensity of 31 spectroscopically identified galaxies at
z
≃ 2.16 (significant at 5.4
σ
) in a 10′ × 11′ region. The overdensity contains two substructures or protoclusters at ⟨
z
⟩ ≃ 2.16 and 2.195 with estimated halo masses at
z
= 0 of ∼5–6 × 10
14
M
⊙
, roughly consistent with Virgo-type clusters. The overdensity total SFR, ∼4000
M
⊙
yr
−1
, is higher than predicted by simulations but much smaller than the SFR derived from the
Planck
data (i.e., 10 173
M
⊙
yr
−1
). The analysis of the
Herschel
data in the field, in combination with the available ancillary data, shows that such a difference is due to an effect of source alignment along the line of sight that produces a 5
σ
overdensity of red
Herschel
sources in the field. We analyze the members’ ultraviolet (UV) spectra and UV-far-infrared spectral energy distributions to derive their SFR, stellar mass, and metallicity. Galaxy members include blue star-forming galaxies and Active galactic nuclei (AGN) with SFRs and stellar masses consistent with the main sequence. Active galactic nuclei, identified through optical spectroscopy or X-ray data, represent a significant fraction (20 ± 10%) of all members of the protocluster at
z
= 2.16, and they are powerful enough to produce radiative feedback. The core of this protocluster, besides being denser, includes members that are, on average, more massive and star-forming and contains a larger fraction of AGN and
Herschel
-detected galaxies than the full sample, suggesting an environmental effect on galaxy growth. A comparison between PHz G237.01+42.50 and other protoclusters in the literature at similar redshifts reveals some common traits and differences that reflect both observational biases and a diversity in intrinsic properties that is not yet fully understood.
Dusty star-forming galaxies at high redshift (1 < z < 3) represent the most intense star-forming regions in the universe. Key aspects to these processes are the gas heating and cooling mechanisms, ...and although it is well known that these galaxies are gas-rich, little is known about the gas excitation conditions. Only a few detailed radiative transfer studies have been carried out owing to a lack of multiple line detections per galaxy. Here we examine these processes in a sample of 24 strongly lensed star-forming galaxies identified by the Planck satellite (LPs) at z ∼ 1.1-3.5. We analyze 162 CO rotational transitions (ranging from Jup = 1 to 12) and 37 atomic carbon fine-structure lines (C i) in order to characterize the physical conditions of the gas in the sample of LPs. We simultaneously fit the CO and C i lines and the dust continuum emission, using two different non-LTE, radiative transfer models. The first model represents a two-component gas density, while the second assumes a turbulence-driven lognormal gas density distribution. These LPs are among the most gas-rich, IR-luminous galaxies ever observed ( L L IR ( 8 − 1000 m ) ∼ 10 13 − 14.6 L ; 〈 LMISM 〉 = (2.7 1.2) × 1012 M , with L ∼ 10-30 the average lens magnification factor). Our results suggest that the turbulent interstellar medium present in the LPs can be well characterized by a high turbulent velocity dispersion ( 〈 ΔVturb 〉 ∼ 100 km s−1) and ratios of gas kinetic temperature to dust temperature 〈 Tkin/Td 〉 ∼ 2.5, sustained on scales larger than a few kiloparsecs. We speculate that the average surface density of the molecular gas mass and IR luminosity, M ISM ∼ 103-4 M pc−2 and L IR ∼ 1011-12 L kpc−2, arise from both stellar mechanical feedback and a steady momentum injection from the accretion of intergalactic gas.
We present a new compilation of Type Ia supernovae (SNe Ia), a new data set of low-redshift nearby-Hubble-flow SNe, and new analysis procedures to work with these heterogeneous compilations. This ...'Union' compilation of 414 SNe Ia, which reduces to 307 SNe after selection cuts, includes the recent large samples of SNe Ia from the Supernova Legacy Survey and ESSENCE Survey, the older data sets, as well as the recently extended data set of distant supernovae observed with the Hubble Space Telescope (HST). A single, consistent, and blind analysis procedure is used for all the various SN Ia subsamples, and a new procedure is implemented that consistently weights the heterogeneous data sets and rejects outliers. We present the latest results from this Union compilation and discuss the cosmological constraints from this new compilation and its combination with other cosmological measurements (CMB and BAO). The constraint we obtain from supernovae on the dark energy density is image, for a flat, Lambda CDM universe. Assuming a constant equation of state parameter, w, the combined constraints from SNe, BAO, and CMB give image. While our results are consistent with a cosmological constant, we obtain only relatively weak constraints on a w that varies with redshift. In particular, the current SN data do not yet significantly constrain w at image. With the addition of our new nearby Hubble-flow SNe Ia, these resulting cosmological constraints are currently the tightest available.
Enterococcus cecorum has been implicated as a possible cause of disease in poultry. However, the characteristics that contribute to pathogenesis of Ent. cecorum in poultry have not been defined. In ...this study, Ent. cecorum from carcass rinsates (n = 75) and diseased broilers and broiler breeders (n = 30) were compared based upon antimicrobial resistance phenotype, the presence of virulence determinants and genetic relatedness using pulsed‐field gel electrophoresis (PFGE). Of the 16 antimicrobials tested, Ent. cecorum from carcass rinsates and clinical cases were resistant to ten and six of the antimicrobials, respectively. The majority of Ent. cecorum from carcass rinsates was resistant to lincomycin (54/75; 72%) and tetracycline (46/75; 61·3%) while the highest level of resistance among clinical Ent. cecorum was to tetracycline (22/30; 73·3%) and erythromycin (11/30; 36·7%). Multidrug resistance (resistance to ≥2 antimicrobials) was identified in Ent. cecorum from carcass rinsates (53/75; 70·7%) and diseased poultry (18/30; 60%). Of the virulence determinants tested, efaAfm was present in almost all of the isolates (104/105; 99%). Using PFGE, the majority of clinical isolates clustered together; however, a few clinical isolates grouped with Ent. cecorum from carcass rinsates. These data suggest that distinguishing the two groups of isolates is difficult based upon the characterization criteria used. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, antimicrobial resistance phenotype, virulence gene profile and genetic relatedness of Enterococcus cecorum isolated from diseased broiler chickens and poultry carcass rinsates were determined. The majority of isolates from both groups were multidrug resistant and harboured few virulence determinants. Results from this study suggest that clinical Ent. cecorum and Ent. cecorum from poultry carcass rinsates may share a common genetic background; clinical Ent. cecorum possess virulence determinants that have not been previously described for this species. Elucidation of those unknown virulence determinants is important for understanding the pathogenesis of Ent. cecorum infections in poultry.
Using Hubble Space Telescope (HST) and Spitzer IRAC imaging, we report the discovery of a very bright strongly lensed Lyman break galaxy (LBG) candidate at image in the field of the massive galaxy ...cluster Abell 1689. The galaxy candidate, which we refer to as A1689-zD1, shows a strong image break of at least 2.2 mag and is completely undetected (<1 capital sigma ) in HST Advanced Camera for Surveys (ACS) g sub(475), r sub(625), i sub(775), and z sub(850) data. These properties, combined with the very blue image and image colors, are exactly the properties of an image LBG, and can only be reasonably fit by a star-forming galaxy at image. Attempts to reproduce these properties with a model galaxy at image yield particularly poor fits. A1689-zD1 has an observed (lensed) magnitude of 24.7 AB (8 capital sigma ) in the NICMOS H sub(160) band and is image1.3 mag brighter than the brightest known z sub(850)-dropout galaxy. When corrected for the cluster magnification of image9.3 at image, the candidate has an intrinsic magnitude of image AB, or about an L sub(*) galaxy at image. The source-plane deprojection shows that the star formation is occurring in compact knots of size image300 pc. The best-fit stellar population synthesis models yield a median redshift of 7.6, stellar masses image M sub(image), stellar ages 45-320 Myr, star formation rates image7.6 M sub(image) yr super(-1), and low reddening with image. These properties are generally similar to those of LBGs found at image. The inferred stellar ages suggest a formation redshift of image (image Gyr). A1689-zD1 is the brightest observed, highly reliable image galaxy candidate found to date.
ABSTRACT
The Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts project aims to identify a population of extremely luminous galaxies using the Planck all-sky survey and to ...explore the nature of their gas fuelling, induced starburst, and the resulting feedback that shape their evolution. Here, we report the identification of 22 high-redshift luminous dusty star-forming galaxies (DSFGs) at z = 1.1–3.3 drawn from a candidate list constructed using the Planck Catalogue of Compact Sources and Wide-field Infrared Survey Explorer all-sky survey. They are confirmed through follow-up dust continuum imaging and CO spectroscopy using AzTEC and the Redshift Search Receiver on the Large Millimeter Telescope Alfonso Serrano. Their apparent infrared luminosities span (0.1–3.1) × 1014 L⊙ (median of 1.2 × 1014 L⊙), making them some of the most luminous galaxies found so far. They are also some of the rarest objects in the sky with a source density of ≲0.01 deg−2. Our Atacama Large Millimeter/submillimeter Array 1.1 mm continuum observations with θ ≈ 0.4 arcsec resolution show clear ring or arc morphologies characteristic of strong lensing. Their lensing-corrected luminosity of LIR ≳ 1013 L⊙ (star-formation rate ≳ 103 M⊙ yr−1) indicates that they are the magnified versions of the most intrinsically luminous DSFGs found at these redshifts. Our spectral energy distribution analysis finds little detectable active galactic nucleus (AGN) activity despite their enormous luminosity, and any AGN activity present must be extremely heavily obscured.
We report on IRAM 30-m/EMIR observations of 38
Herschel
sources chosen as the brightest red submillimeter (submm) sources in 18
Planck
-selected fields drawn from the
Planck
high-
z
(PHz) sample of ...protocluster candidates. These fields host overdensities of red
Herschel
sources, with high star formation rates (∼10 000
M
⊙
yr
−1
), as obtained from the
Planck
measurements. The goals of these observations are to measure the spectroscopic redshifts of the
Herschel
sources in the PHz fields, investigate the origin of their bright submm emission, and find evidence of their association with high-
z
protoclusters. We detected 40 CO lines on a total of 24 bright (
S
350 μm
> 40 mJy)
Herschel
sources in 14 of the 18 PHz fields. The measured average redshift is ⟨
z
CO
⟩ = 2.25 ± 0.09, spanning a range from 1.32 to 2.75. We measured the redshifts for multiple
Herschel
sources in projected proximity in eight PHz fields. In half of those fields, we detected between two and three objects at similar redshifts, supporting the idea that the PHz fields contain high-
z
protoclusters. The detection of sources at different redshifts in the same field demonstrates that foreground and background sources also contribute to the total submm emission. We compared the properties of the molecular gas and of the star formation activity of our sources with samples of normal star-forming galaxies (SFGs), submm galaxies (SMGs), and CO-detected cluster and protocluster galaxies drawn from the literature at similar redshifts. We find that the PHz-IRAM sources are mainly normal SFGs, with only ∼20% undergoing a starburst phase. The PHz-IRAM sources are characterized by star formation rates (⟨SFR⟩ = 1043 ± 157
M
⊙
yr
−1
) and gas masses (⟨
M
gas
⟩ = (4.0 ± 0.7) × 10
11
M
⊙
) that are, on average, eight and five times higher than those typical of normal SFGs at similar redshifts. Their dust temperatures (⟨
T
dust
⟩ = 29.2 ± 0.9 K) and depletion timescales (⟨
τ
dep
⟩ = 0.47 ± 0.07 Gyr) are instead consistent with those of normal SFGs. The analysis of the CO spectral line energy distribution, available for ten PHz-IRAM sources, peaks at a low quantum rotation number (
J
up
= 3) in most of the cases, implying low gas excitation. These properties imply that a significant number of PHz-IRAM sources contain extended and cold molecular gas reservoirs at low excitation and that their star formation is driven by secular processes. Multiplicity and moderate gravitational lensing might also play a role in producing the observed properties. Some of these properties are also observed in other CO-detected infrared-luminous protocluster galaxies at
z
≃ 1.3 − 3. We find that the protoclusters with the highest level of star formation, drawn from the largest volume simulations available to date, exhibit similar SFRs as compared to the PHz protoclusters; however, they separate out into a higher number of star-forming galaxies. Millimeter and CO observations at higher spatial resolution than those presented here would be necessary to further elucidate the properties of our PHz-IRAM sources and determine which mechanisms drive star formation in infrared-luminous protocluster galaxies.
We present high-resolution ultraviolet spectra of absorption-line systems towards the low-z quasi-stellar object (QSO) HS 0624+6907 (zQSO= 0.3700). Coupled with ground-based imaging and spectroscopic ...galaxy redshifts, we find evidence that many of these absorbers do not arise in galaxy haloes but rather are truly intergalactic gas clouds distributed within large-scale structures, and moreover, the gas is cool (T < 105 K) and has relatively high metallicity (Z > 0.9 Z⊙). Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) data reveal a dramatic cluster of 13 H i Lyman α (Lyα) lines within a 1000 km s−1 interval at zabs= 0.0635. We find 10 galaxies at this redshift with impact parameters ranging from ρ= 135 h−170 kpc to 1.37 h−170 Mpc. The velocities and velocity spread of the Lyα lines in this complex are unlikely to arise in the individual haloes of the nearby galaxies; instead, we attribute the absorption to intragroup medium gas, possibly from a large-scale filament viewed along its long axis. Contrary to theoretical expectations, this gas is not the shock-heated warm-hot intergalactic medium (WHIM); the width of the Lyα lines all indicate a gas temperature T≪ 105 K, and metal lines detected in the Lyα complex also favour photoionized, cool gas. No O vi absorption lines are evident, which is consistent with photoionization models. Remarkably, the metallicity is near-solar, M/H=−0.05 ± 0.4 (2σ uncertainty), yet the nearest galaxy which might pollute the intergalactic medium is at least 135 h−170 kpc away. Tidal stripping from nearby galaxies appears to be the most likely origin of this highly enriched, cool gas. More than six Abell galaxy clusters are found within 4° of the sight line suggesting that the QSO line of sight passes near a node in the cosmic web. At z≈ 0.077, we find absorption systems as well as galaxies at the redshift of the nearby clusters Abell 564 and Abell 559. We conclude that the sight line pierces a filament of gas and galaxies feeding into these clusters. The absorber at zabs= 0.075 73 associated with Abell 564/559 also has a high metallicity with C/H > −0.6, but again the closest galaxy is relatively far from the sight line (ρ= 293 h−170 kpc). The Doppler parameters and H i column densities of the Lyα lines observed along the entire sight line are consistent with those measured towards other low-z QSOs, including a number of broad (b > 40 km s−1) Lyα lines.
We present the discovery of a large-scale structure of emission-line galaxies at redshift z= 4.86 behind a massive cluster of galaxies, A1689. Previous spectroscopic observations of a galaxy, ...A1689−7.1 at z= 4.87, near this structure, revealed a possible overdense region of intergalactic medium (IGM) around the galaxy, which extends at least ∼80 comoving Mpc along the line of sight. In order to investigate whether this z∼ 5 IGM overdense region contains a galaxy overdensity, we undertook narrow- and broad-band imaging observations around A1689−7.1 with Subaru/Suprime-Cam. We detected 51 candidates as Lyα emitters at redshift z= 4.86 ± 0.03 in the 32 × 24 arcmin2 field of view. After correction for lensing by the foreground cluster, we found a large-scale (∼20 × 60 comoving Mpc) overdense region of galaxies around A1689−7.1 in the source plane at z= 4.86. The densest peak in this region has an overdensity of δ∼ 4, suggesting that this structure is probably a good candidate for a protocluster which may evolve into a massive cluster of galaxies in the present-day Universe. A1689−7.1 is located at the edge of this region, where the local galaxy density is ∼1.6 times the mean density and is close to the density contrast in the IGM along the line of sight to A1689−7.1 estimated from the optical depth. The overdensities of galaxies we have found may suggest that at least some parts of the IGM overdense region have already started to form galaxies and moreover they relate to the formation of a protocluster. Although we lack information on the three-dimensional distributions of both IGM and galaxy overdense regions, the similarity of the scales of both regions may suggest that the two are parts of a single large-scale structure, which would be an large edge-on sheet along the line of sight with a size of ∼20 × 60 × 80 comoving Mpc.
The human immunodeficiency virus (HIV) Tat protein is acetylated by the transcriptional coactivator p300, a necessary step in Tat-mediated transactivation. We report here that Tat is deacetylated by ...human sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent class III protein deacetylase in vitro and in vivo. Tat and SIRT1 coimmunoprecipitate and synergistically activate the HIV promoter. Conversely, knockdown of SIRT1 via small interfering RNAs or treatment with a novel small molecule inhibitor of the SIRT1 deacetylase activity inhibit Tat-mediated transactivation of the HIV long terminal repeat. Tat transactivation is defective in SIRT1-null mouse embryonic fibroblasts and can be rescued by expression of SIRT1. These results support a model in which cycles of Tat acetylation and deacetylation regulate HIV transcription. SIRT1 recycles Tat to its unacetylated form and acts as a transcriptional coactivator during Tat transactivation.
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