We present the public release of the stellar mass catalogs for the GOODS-S and UDS fields obtained using some of the deepest near-IR images available, achieved as part of the Cosmic Assembly ...Near-infrared Deep Extragalactic Legacy Survey project. We combine the effort from 10 different teams, who computed the stellar masses using the same photometry and the same redshifts. Each team adopted their preferred fitting code, assumptions, priors, and parameter grid. The combination of results using the same underlying stellar isochrones reduces the systematics associated with the fitting code and other choices. Thanks to the availability of different estimates, we can test the effect of some specific parameters and assumptions on the stellar mass estimate. The choice of the stellar isochrone library turns out to have the largest effect on the galaxy stellar mass estimates, resulting in the largest distributions around the median value (with a semi interquartile range larger than 0.1 dex). On the other hand, for most galaxies, the stellar mass estimates are relatively insensitive to the different parameterizations of the star formation history. The inclusion of nebular emission in the model spectra does not have a significant impact for the majority of galaxies (less than a factor of 2 for ~80% of the sample). Nevertheless, the stellar mass for the subsample of young galaxies (age <100 Myr), especially in particular redshift ranges (e.g., 2.2 < z < 2.4, 3.2 < z < 3.6, and 5.5 < z < 6.5), can be seriously overestimated (by up to a factor of 10 for <20 Myr sources) if nebular contribution is ignored.
We present a multi-wavelength photometric catalog in the COSMOS field as part of the observations by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The catalog is based on Hubble ...Space Telescope Wide Field Camera 3 (HST/WFC3) and Advanced Camera for Surveys observations of the COSMOS field (centered at R.A.: , Decl.: ). The final catalog has 38671 sources with photometric data in 42 bands from UV to the infrared ( ). This includes broadband photometry from HST, CFHT, Subaru, the Visible and Infrared Survey Telescope for Astronomy, and Spitzer Space Telescope in the visible, near-infrared, and infrared bands along with intermediate- and narrowband photometry from Subaru and medium-band data from Mayall NEWFIRM. Source detection was conducted in the WFC3 F160W band (at 1.6 m) and photometry is generated using the Template FITting algorithm. We further present a catalog of the physical properties of sources as identified in the HST F160W band and measured from the multi-band photometry by fitting the observed spectral energy distributions of sources against templates.
The redshifts of all cosmologically distant sources are expected to experience a small, systematic drift as a function of time due to the evolution of the Universe's expansion rate. A measurement of ...this effect would represent a direct and entirely model-independent determination of the expansion history of the Universe over a redshift range that is inaccessible to other methods. Here we investigate the impact of the next generation of Extremely Large Telescopes on the feasibility of detecting and characterizing the cosmological redshift drift. We consider the Lyα forest in the redshift range 2 < z < 5 and other absorption lines in the spectra of high-redshift QSOs as the most suitable targets for a redshift drift experiment. Assuming photon-noise-limited observations and using extensive Monte Carlo simulations we determine the accuracy to which the redshift drift can be measured from the Lyα forest as a function of signal-to-noise ratio and redshift. Based on this relation and using the brightness and redshift distributions of known QSOs we find that a 42-m telescope is capable of unambiguously detecting the redshift drift over a period of ∼20 yr using 4000 h of observing time. Such an experiment would provide independent evidence for the existence of dark energy without assuming spatial flatness, using any other cosmological constraints or making any other astrophysical assumption.
We report the detection of the CO 4–3, 6–5, 9–8, 10–9, and 11–10 lines in the Broad Absorption Line quasar APM 08279+5255 at $z=3.9$ using the IRAM 30 m telescope. We also present IRAM PdBI high ...spatial resolution observations of the CO 4–3 and 9–8 lines, and of the 1.4 mm dust radiation as well as an improved spectrum of the HCN(5–4) line. Unlike CO in other QSO host galaxies, the CO line SED of APM 08279+5255 rises up to the CO(10–9) transition. The line fluxes in the CO ladder and the dust continuum fluxes are best fit by a two component model, a “cold” component at ~$ 65$ K with a high density of n(H2) = 1$\times$105 cm-3, and a “warm”, ~$ 220$ K component with a density of 1$\times$104 cm-3. We show that IR pumping via the 14 $\mu{\rm m}$ bending mode of HCN is the most likely channel for the HCN excitation. From our models we find, that the CO(1–0) emission is dominated by the dense gas component which implies that the CO conversion factor is higher than usually assumed for high-z galaxies with $\alpha \approx$ 5$ M_{\odot}$ (K km s-1 pc2)-1. Using brightness temperature arguments, the results from our high-resolution mapping, and lens models from the literature, we argue that the molecular lines and the dust continuum emission arise from a very compact (r ≈ 100-300 pc), highly gravitationally magnified ($ m = 60{-}110$) region surrounding the central AGN. Part of the difference relative to other high-z QSOs may therefore be due to the configuration of the gravitational lens, which gives us a high-magnification zoom right into the central 200-pc radius of APM 08279+5255 where IR pumping plays a significant role for the excitation of the molecular lines.
Dense gas in luminous infrared galaxies Baan, W. A.; Henkel, C.; Loenen, A. F. ...
Astronomy and astrophysics (Berlin),
01/2008, Letnik:
477, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Aims.Molecules that trace the high-density regions of the interstellar medium have been observed in (ultra-)luminous (far-)infrared galaxies, in order to initiate multiple-molecule ...multiple-transition studies to evaluate the physical and chemical environment of the nuclear medium and its response to the ongoing nuclear activity. Methods.The HCN(1-0), HNC(1-0), ${\rm HCO}^+$(1-0), CN(1-0) and CN(2-1), CO(2-1), and CS(3-2) transitions were observed in sources covering three decades of infrared luminosity including sources with known OH megamaser activity. The data for the molecules that trace the high-density regions were augmented with data available in the literature. Results.The integrated emissions of high-density tracer molecules show a strong relation to the far-infrared luminosity. Ratios of integrated line luminosities were used for a first-order diagnosis of the integrated molecular environment of the evolving nuclear starbursts. Diagnostic diagrams display significant differentiation among the sources that relate to the initial conditions and the radiative excitation environment. Initial differentiation was introduced between the FUV radiation field in photon-dominated-regions and the X-ray field in X-ray-dominated-regions. The galaxies displaying OH megamaser activity have line ratios typical of photon-dominated regions.
We use data taken as part of Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) observations of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) to identify massive ...and evolved galaxies at 3 < z < 4.5. This is performed using the strength of the Balmer break feature at rest-frame 3648 A, which is a diagnostic of the age of the stellar population in galaxies. Using the WFC3 H-band-selected catalog for the CANDELS GOODS-S field and deep multi-waveband photometry from optical (HST) to mid-infrared (Spitzer) wavelengths, we identify a population of old and evolved post-starburst galaxies based on the strength of their Balmer breaks (Balmer break galaxies, BBGs). The galaxies are also selected to be bright in rest-frame near-IR wavelengths and hence massive. We identify a total of 16 BBGs. Fitting the spectral energy distribution of the BBGs shows that the candidate galaxies have average estimated ages of ~800 Myr and average stellar masses of ~5 x 10 super(10) M sub(middot in circle), consistent with being old and massive systems. Two of our BBG candidates are also identified by the criteria that are sensitive to star-forming galaxies (Lyman break galaxy selection). We find a number density of ~3.2 x 10 super(-5) Mpc super(-3) for the BBGs, corresponding to a mass density of ~2.0 x 10 super(6) M sub(middot in circle) Mpc super(-3) in the redshift range covering the survey. Given the old age and the passive evolution, it is argued that some of these objects formed the bulk of their mass only a few hundred million years after the big bang.
We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the ...30 m IRAM telescope in the CO(2–1) line, achieving a resolution of 12″ × 2.6 km s-1, enabling individual giant molecular clouds (GMCs) to be resolved. The observed region is 650 square arcminutes mainly along the major axis and out to a radius of 8.5 kpc, and covers entirely the 2′ × 40′ radial strip observed with the HIFI and PACS Spectrometers as part of the HERM33ES Herschel key program. The achieved sensitivity in main-beam temperature is 20–50 mK at 2.6 km s-1 velocity resolution. The CO(2–1) luminosity of the observed region is 1.7 ± 0.1 × 107 K km s-1 pc2 and is estimated to be 2.8 ± 0.3 × 107 K km s-1 pc2 for the entire galaxy, corresponding to H2 masses of 1.9 × 108 M⊙ and 3.3 × 108 M⊙ respectively (including He), calculated with N(H2)/ICO(1 − 0) twice the Galactic value due to the half-solar metallicity of M 33. The H i 21 cm VLA archive observations were reduced, and the mosaic was imaged and cleaned using the multi-scale task in the CASA software package, yielding a series of datacubes with resolutions ranging from 5″ to 25″. The H i mass within a radius of 8.5 kpc is estimated to be 1.4 × 109 M⊙ . The azimuthally averaged CO surface brightness decreases exponentially with a scale length of 1.9 ± 0.1 kpc whereas theatomic gas surface density is constant at ΣHi = 6 ± 2 M⊙ pc-2 deprojected to face-on. For an N(H2)/ICO(1 − 0) conversion factor twice that of the Milky Way, the central kiloparsec H2 surface density is ΣH2 = 8.5 ± 0.2 M⊙ pc-2. The star formation rate per unit molecular gas (SF efficiency, the rate of transformation of molecular gas into stars), as traced by the ratio of CO to Hα and FIR brightness, is constant with radius. The SFE, with a N(H2)/ICO(1 − 0) factor twice galactic, appears 2–4 times greater than for large spiral galaxies. A morphological comparison of molecular and atomic gas with tracers of star formation is presented showing good agreement between these maps both in terms of peaks and holes. A few exceptions are noted. Several spectra, including those of a molecular cloud situated more than 8 kpc from the galaxy center, are presented.
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the CII 157.7 mu m fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z = 4.7, ...BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submillimeter galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4" (25 kpc) region. All three galaxies are detected in the submillimeter continuum, indicating FIR luminosities in excess of 10 super(13) L sub(middot in circle) for the two most luminous objects. The SMG and the quasar host galaxy are both detected in CII line emission with luminosities L sub(CII) = (10.0 + or - 1.5) x 10 super(9) L sub(middot in circle) and L sub(CII) = (6.5 + or - 1.0) x 10 super(9) L sub(middot in circle), respectively. We estimate a luminosity ratio L sub(CII)/L sub(FIR) = (8.3 + or - 1.2) x 10 super(-4) for the starburst SMG to the north and L sub(CII)/L sub(FIR) = (2.5 + or - 0.4) x 10 super(-4) for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower CII-to-FIR luminosity ratios in quasars than in starburst galaxies. The third fainter object with a flux density S sub(340 GHz) = 1.9 + or - 0.3 mJy is coincident with a Ly alpha emitter and is detected in HST ACS F775W and F814W images but has no clear counterpart in the H band. Even if this third companion does not lie at a redshift similar to BR1202-0725, the quasar and the SMG represent an overdensity of massive, infrared luminous star-forming galaxies within 1.3 Gyr of the big bang.
We report results from a search for massive and evolved galaxies at image in the GOODS southern field. Combining HST ACS, VLT ISAAC, and Spitzer IRAC broadband photometric data, we develop a color ...selection technique to identify candidates for being evolved galaxies at high redshifts. The color selection is primarily based on locating the Balmer break using the K and 3.6 mum bands. Stellar population synthesis models are fitted to the SEDs of these galaxies to identify the final sample. We find 11 candidates with photometric redshifts in the range image, dominated by an old stellar population, with ages 0.2-1.0 Gyr. The stellar masses are in the range image. One candidate has a spectroscopically confirmed redshift, in good agreement with our photometric redshift. The galaxies are very compact, with half-light radii in the observed K band smaller than image2 kpc. Seven of the 11 candidates are also detected at 24 mum with the MIPS instrument on Spitzer. While the observed 24 mum emission is consistent with an obscured AGN, we define a 'no-MIPS' sample of candidates in addition to the full sample. Results will be quoted for both samples. If the stellar mass estimates are correct, the presence of these massive and evolved galaxies when the universe was image1 Gyr old could suggest that conversion of baryons into stars proceeded more efficiently in the early universe than it does today.
We have detected the four 18 cm OH lines from the z approximaetely 0.765 gravitational lens toward PMN J0134-0931. The 1612 and 1720 MHz lines are in conjugate absorption and emission, providing a ...laboratory to test the evolution of fundamental constants over a large lookback time. We compare the HI and OH main line absorption redshifts of the different components in the z approximately 0.765 absorber and the z approximately 0.685 lens toward B0218 + 357 to place stringent constraints on changes in F triple-bond g(p)alpha(2)/mu(1.57). We obtain DeltaF/F = (0.44 +/- 0.36(stat) +/- 1.0(sys)t) x 10(-5), consistent with no evolution over the redshift range 0 < z < or = 0.7. The measurements have a 2sigma sensitivity of Deltaalpha/alpha < 6.7 x 10(-6) or Deltamu/mu < 1.4 x 10(-5) to fractional changes in alpha and mu over a period of approximately 6.5 G yr, half the age of the Universe. These are among the most sensitive constraints on changes in mu.
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![[C II] LINE EMISSION IN MAS...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2041-8205/small "[C II] LINE EMISSION IN MASSIVE STAR-FORMING GALAXIES AT z = 4.7")
