Recursos de colección

Caltech Authors (147.820 recursos)

Repository of works by Caltech published authors.

Group = COSMOS

Mostrando recursos 1 - 20 de 339

  1. Constraints on Quenching of Z ≲ 2 Massive Galaxies from the Evolution of the Average Sizes of Star-forming and Quenched Populations in COSMOS

    Faisst, A. L.; Carollo, C. M.; Capak, P. L.; Tacchella, S.; Renzini, A.; Ilbert, O.; McCracken, H. J.; Scoville, N. Z.
    We use >9400 log(m/M☉) > 10 quiescent and star-forming galaxies at z ≾ 2 in COSMOS/UltraVISTA to study the average size evolution of these systems, with focus on the rare ultra-massive population at log(m/M_☉) > 11.4. The large 2 square degree survey area delivers a sample of ~400 such ultra-massive systems. Accurate sizes are derived using a calibration based on high-resolution images from the Hubble Space Telescope. We find that at these very high masses, the size evolution of star-forming and quiescent galaxies is almost indistinguishable in terms of normalization and power-law slope. We use this result to investigate possible...

  2. HR-COSMOS: Kinematics of star-forming galaxies at z ~ 0.9

    Pelliccia, D.; Tresse, L.; Epinat, B.; Ilbert, O.; Scoville, N.; Amram, P.; Lemaux, B. C.; Zamorani, G.
    We present the kinematic analysis of a sub-sample of 82 galaxies at 0.75 < z < 1.2 from our new survey HR-COSMOS aimed to obtain the first statistical sample to study the kinematics of star-forming galaxies in the treasury COSMOS field at 0 < z < 1.2. We observed 766 emission line galaxies using the multi-slit spectrograph ESO-VLT/VIMOS in high-resolution mode (R = 2500). To better extract galaxy kinematics, VIMOS spectral slits have been carefully tilted along the major axis orientation of the galaxies, making use of the position angle measurements from the high spatial resolution HST/ACS COSMOS images. We...

  3. Evolution of Interstellar Medium, Star Formation, and Accretion at High Redshift

    Scoville, N.; Lee, N.; Vanden Bout, P.; Díaz-Santos, T.; Sanders, D.; Darvish, B.; Bongiorno, A.; Casey, C. M.; Murchikova, L.; Koda, J.; Capak, P.; Vlahakis, Catherine; Ilbert, O.; Sheth, K.; Morokuma-Matsui, K.; Ivison, R. J.; Aussel, H.; Laigle, C.; McCracken, H. J.; Armus, L.; Pope, A.; Toft, S.; Masters, D.
    ALMA observations of the long wavelength dust continuum are used to estimate the interstellar medium (ISM) masses in a sample of 708 galaxies at z = 0.3 to 4.5 in the COSMOS field. The galaxy sample has known far-infrared luminosities and, hence, star formation rates (SFRs) and stellar masses (M∗) from the optical–infrared spectrum fitting. The galaxies sample SFRs from the main sequence (MS) to 50 times above the MS. The derived ISM masses are used to determine the dependence of gas mass on redshift, M∗, and specific SFR (sSFR) relative to the MS. The ISM masses increase approximately with...

  4. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. IV. Physical properties derived from spectral energy distributions

    Miettinen, O.; Delvecchio, I.; Smolčić, V.; Novak, M.; Aravena, M.; Karim, A.; Murphy, E. J.; Schinnerer, E.; Capak, P.; Ilbert, O.; Intema, H. T.; Laigle, C.; McCracken, H. J.
    Context. Submillimetre galaxies (SMGs) in the early Universe are potential antecedents of the most massive galaxies we see in the present-day Universe. An important step towards quantifying this galactic evolutionary connection is to investigate the fundamental physical properties of SMGs, such as their stellar mass content (M⋆) and star formation rate (SFR). Aims. We attempt to characterise the physical nature of a 1.1 mm selected, flux-limited, and interferometrically followed up sample of SMGs in the COSMOS field. Methods. We used the latest release of the MAGPHYS code to fit the multiwavelength (UV to radio) spectral energy distributions (SEDs) of 16 of the...

  5. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. III. Environments

    Smolčić, V.; Miettinen, O.; Tomičić, N.; Zamorani, G.; Finoguenov, A.; Lemaux, B. C.; Aravena, M.; Capak, P.; Chiang, Y.-K.; Civano, F.; Delvecchio, I.; Ilbert, O.; Jurlin, N.; Karim, A.; Laigle, C.; Le Fèvre, O.; Marchesi, S.; McCracken, H. J.; Riechers, D. A.; Salvato, M.; Schinnerer, E.; Tasca, L.; Toft, S.
    We investigate the environment of 23 submillimetre galaxies (SMGs) drawn from a signal-to-noise (S/N)-limited sample of SMGs originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey of a Cosmic Evolution Survey (COSMOS) subfield and then followed up with the Submillimetre Array and Plateau de Bure Interferometer at 890 μm and 1.3 mm, respectively. These SMGs already have well-defined multiwavelength counterparts and redshifts. We also analyse the environments of four COSMOS SMGs spectroscopically confirmed to lie at redshifts z_(spec) > 4.5, and one at z_(spec) = 2.49 resulting in a total SMG sample size of 28. We...

  6. VIMOS Ultra-Deep Survey (VUDS): IGM transmission towards galaxies with 2.5 < z < 5.5 and the colour selection of high-redshift galaxies

    Thomas, R.; Capak, P.; Scoville, N.
    The observed UV rest-frame spectra of distant galaxies are the result of their intrinsic emission combined with absorption along the line of sight produced by the inter-galactic medium (IGM). Here we analyse the evolution of the mean IGM transmission Tr(Lyα) and its dispersion along the line of sight for 2127 galaxies with 2.5 < z < 5.5 in the VIMOS Ultra Deep Survey (VUDS). We fitted model spectra combined with a range of IGM transmission to the galaxy spectra using the spectral fitting algorithm GOSSIP+. We used these fits to derive the mean IGM transmission towards each galaxy for several...

  7. Ultraluminous infrared galaxies and the origin of quasars

    Sanders, D. B.; Soifer, B. T.; Elias, J. H.; Madore, B. F.; Matthews, K.; Neugebauer, G.; Scoville, N. Z.
    An evolutionary connection between ultraluminous infrared galaxies and quasars is deduced from the observations of all 10 infrared galaxies with luminosities L(8-1000 μm) ≥ 10^(12) L⊙, taken from a flux-limited sample of infrared bright galaxies. Images of the infrared galaxies show that nearly all are strongly interacting merger systems with exceptionally luminous nuclei. Millimeter-wave CO observations show that these objects typically contain 0.5-2 x 10^(10) M⊙ of H_2. Optical spectra indicate a mixture of starburst and active galactic nucleus (AGN) energy sources, both of which are apparently fueled by the tremendous reservoir of molecular gas. It is proposed that these ultraluminous...

  8. Cosmic Web of Galaxies in the COSMOS Field: Public Catalog and Different Quenching for Centrals and Satellites

    Darvish, Behnam; Mobasher, Bahram; Martin, D. Christopher; Sobral, David; Scoville, Nick; Stroe, Andra; Hemmati, Shoubaneh; Kartaltepe, Jeyhan
    We use a mass complete (log(M/M⊙) ⩾ 9.6) sample of galaxies with accurate photometric redshifts in the COSMOS field to construct the density field and the cosmic web to z = 1.2. The comic web extraction relies on the density field Hessian matrix and breaks the density field into clusters, filaments, and the field. We provide the density field and cosmic web measures to the community. We show that at z ≾ 0.8, the median star formation rate (SFR) in the cosmic web gradually declines from the field to clusters and this decline is especially sharp for satellites (~1 dex...

  9. High-Resolution Infrared Imaging of the Compact Nuclear Source in NGC 4258

    Chary, R.; Becklin, E. E.; Evans, A. S.; Neugebauer, G.; Scoville, N. Z.; Matthews, K.; Ressler, M. E.
    We present high-resolution imaging of the nucleus of NGC 4258 from 1 to 18 μm. Our observations reveal that the previously discovered compact source of emission is unresolved even at the near-infrared resolution of ~0.”2 FWHM, which corresponds to about 7 pc at the distance of the galaxy. This is consistent with the source of emission being the region in the neighborhood of the purported 3.5 × 10^7 M☉ black hole. After correcting for about 18 mag of visual extinction, the infrared data are consistent with an F_ν ∝ ν^(-1.4±0.1) spectrum from 1.1 to 18 μm, implying a nonthermal origin....

  10. Imaging of NGC 5907's stellar stream

    Laine, Seppo; Grillmair, Carl J.; Martínez-Delgado, David; Romanowsky, Aaron J.; Capak, Peter L.; Arendt, Richard G.; Ashby, Matthew L. N.; Davies, James E.; Majewski, Steven R.; GaBany, R. Jay
    We have obtained deep g, r, and i-band Subaru and ultra-deep 3.6 μm IRAC images of parts of the multiply-wrapped stellar stream around the nearby edge-on galaxy NGC 5907. We have fitted the surface brightness measurements of the stream with FSPS stellar population synthesis models to derive the metallicity and age of the brightest parts of the stream. The resulting relatively high metallicity ([Fe/H] = −0.3) is consistent with a major merger scenario but a satellite accretion event cannot be ruled out.

  11. Planck 2015 results. VIII. High Frequency Instrument data processing: Calibration and maps

    Adam, R.; Bock, J. J.; Crill, B. P.; Doré, O.; Hildebrandt, S. R.; Pearson, T. J.; Prézeau, G.; Rocha, G.; Seiffert, M. D.; McGehee, P.; Rusholme, B.
    This paper describes the processing applied to the cleaned, time-ordered information obtained from the Planck High Frequency Instrument (HFI) with the aim of producing photometrically calibrated maps in temperature and (for the first time) in polarization. The data from the entire 2.5-year HFI mission include almost five full-sky surveys. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To obtain the best accuracy on the calibration over such a large range, two different photometric calibration schemes have been used. The 545 and 857 GHz data are calibrated using models of planetary atmospheric emission. The lower frequencies...

  12. Planck 2015 results. XX. Constraints on inflation

    Ade, P. A. R.; Bock, J. J.; Crill, B. P.; Doré, O.; Hildebrandt, S. R.; Pearson, T. J.; Prézeau, G.; Rocha, G.; Seiffert, M. D.; Chary, R.-R.; McGehee, P.; Paladini, R.; Rusholme, B.
    We present the implications for cosmic inflation of the Planck measurements of the cosmic microwave background (CMB) anisotropies in both temperature and polarization based on the full Planck survey, which includes more than twice the integration time of the nominal survey used for the 2013 release papers. The Planck full mission temperature data and a first release of polarization data on large angular scales measure the spectral index of curvature perturbations to be ns = 0.968 ± 0.006 and tightly constrain its scale dependence to dns/ dlnk = −0.003 ± 0.007 when combined with the Planck lensing likelihood. When the...

  13. Dense Molecular Gas Tracers in the Outflow of the Starburst Galaxy NGC 253

    Walter, Fabian; Bolatto, Alberto D.; Leroy, Adam K.; Veilleux, Sylvain; Warren, Steven R.; Hodge, Jacqueline; Levy, Rebecca C.; Meier, David S.; Ostriker, Eve C.; Ott, Jürgen; Rosolowsky, Erik; Scoville, Nick; Weiss, Axel; Zschaechner, Laura; Zwaan, Martin
    We present a detailed study of a molecular outflow feature in the nearby starburst galaxy NGC 253 using ALMA. We find that this feature is clearly associated with the edge of NGC 253's prominent ionized outflow, has a projected length of ~300 pc, with a width of ~50 pc, and a velocity dispersion of ~40 km s^(−1), which is consistent with an ejection from the disk about 1 Myr ago. The kinematics of the molecular gas in this feature can be interpreted (albeit not uniquely) as accelerating at a rate of 1 km s^(−1) pc^(−1). In this scenario, the gas...

  14. What Lurks in ULIRGs?—Probing the Chemistry and Excitation of Molecular Gas in the Nuclei of Arp 220 and NGC 6240

    Manohar, Swarnima; Scoville, Nick
    We have imaged the dense star-forming regions of Arp 220 and NGC 6240 in the 3 mm band transitions of CO, HCN, HCO^+, HNC, and CS at 0farcs5–0farcs8 resolution using CARMA. Our data set images all these lines at similar resolutions and high sensitivity, and can be used to derive line ratios of faint high excitation lines. In both the nuclei of Arp 220, the HCN/HNC ratios suggest chemistry of X-ray Dominated Regions (XDRs)—a likely signature of an active galactic nucleus. In NGC 6240, there is no evidence of XDR type chemistry, but there the bulk of the molecular gas...

  15. ALMA Reveals Weak [N II] Emission in "Typical" Galaxies and Intense Starbursts at z = 5–6

    Pavesi, Riccardo; Riechers, Dominik A.; Capak, Peter L.; Carilli, Christopher L.; Sharon, Chelsea E.; Stacey, Gordon J.; Karim, Alexander; Scoville, Nicholas Z.; Smolčić, Vernesa
    We report interferometric measurements of [N II] 205 μm fine-structure line emission from a representative sample of three galaxies at z = 5–6 using the Atacama Large (sub)Millimeter Array (ALMA). These galaxies were previously detected in [C II] and far-infrared continuum emission and span almost two orders of magnitude in star formation rate (SFR). Our results show at least two different regimes of ionized interstellar medium properties for galaxies in the first billion years of cosmic time, separated by their L_([C II])/L_([N II]) ratio. We find extremely low [N II] emission compared to [C II] (L_([C II])/L_([N II]) = 68^(+200)_(-28))...

  16. High-Redshift Protoclusters Traced by Submillimeter Galaxies: Tracing Star Formation Activity out to z > 4

    Menéndez-Delmestre, Karín; Capak, Peter; Sheth, Kartik
    Clustering analysis indicate that at z ~ 2 submm-selected galaxies (SMGs) reside in very massive halos (M_(DM) > 5 × 10^(13)), suggesting that SMGs trace high-density environments that evolve into rich galaxy clusters. Conversely, recent work suggests that SMGs are tracers of a broader range of environments, including structures with more modest masses caught in highly active periods; since galaxies in these structures are likely caught during episodes of peak starbursts, SMGs may be tracers of a wider range of environments beyond the progenitors of todays very rich clusters, opening a window for a more complete exploration of the details...

  17. High-resolution Observations of Molecular Lines in Arp 220: Kinematics, Morphology, and Limits on the Applicability of the Ammonia Thermometer

    Zschaechner, Laura K.; Ott, Jürgen; Walter, Fabian; Meier, David S.; Momjian, Emmanuel; Scoville, Nick
    We observe Arp 220, the nearest ultra-luminous infrared galaxy, over 4 GHz in the K and Ka bands, providing constraints for the kinematics and morphology, and identifying molecular species on scales resolving both nuclei (0".6 or 230 pc). We detect multiple molecular species, including hydroxyl (OH ^2Π_(3/2)J = 9/2 F= 4-4; 5-5) in both cores, and tentatively detect H_2O(6_(15)-5_(23)) at ~21.84 GHz in both nuclei, indicating the likely presence of maser emission. The observed frequency range also contains metastable ammonia transitions from (J, K) = (1, 1)–(5, 5), as well as the (9, 9) inversion line; together, they are a...

  18. The COSMOS2015 Catalog: Exploring the 1 < z < 6 Universe with Half a Million Galaxies

    Laigle, C.; Capak, P.; Scoville, N.
    We present the COSMOS2015 catalog, which contains precise photometric redshifts and stellar masses for more than half a million objects over the 2deg^2 COSMOS field. Including new YJHK_s images from the UltraVISTA-DR2 survey, Y-band images from Subaru/Hyper-Suprime-Cam, and infrared data from the Spitzer Large Area Survey with the Hyper-Suprime-Cam Spitzer legacy program, this near-infrared-selected catalog is highly optimized for the study of galaxy evolution and environments in the early universe. To maximize catalog completeness for bluer objects and at higher redshifts, objects have been detected on a χ^2 sum of the YJHK_s and z^(++) images. The catalog contains ~6 x...

  19. The Effects of the Local Environment and Stellar Mass on Galaxy Quenching to z ~ 3

    Darvish, Behnam; Mobasher, Bahram; Sobral, David; Rettura, Alessandro; Scoville, Nick; Faisst, Andreas; Capak, Peter
    We study the effects of the local environment and stellar mass on galaxy properties using a mass complete sample of quiescent and star-forming systems in the COSMOS field at z ≾ 3. We show that at z ≾ 1 the median star formation rate (SFR) and specific SFR (sSFR) of all galaxies depend on the environment, but they become independent of the environment at z ≳ 1. However, we find that only for star-forming galaxies, the median SFR and sSFR are similar in different environments regardless of redshift and stellar mass. We find that the quiescent fraction depends on the...

  20. A Tight Relation between N/O Ratio and Galaxy Stellar Mass Can Explain the Evolution of Strong Emission Line Ratios with Redshift

    Masters, Daniel; Faisst, Andreas; Capak, Peter
    The offset of high-redshift star-forming galaxies in the [O III]/Hβ versus [N II]/Hα (O3N2) diagram in comparison with the local star-forming galaxy sequence is now well established. The physical origin of the shift is the subject of some debate and has important implications for metallicity measurements based on strong lines at all redshifts. To investigate the origin of the O3N2 offset, we use a sample of ~100,000 star-forming galaxies from the Sloan Digital Sky Survey DR12 to understand how measurable galaxy physical properties (Σ_(SFR), ionization parameter, nitrogen-to-oxygen (N/O) ratio, and stellar mass) drive galaxy position in two key diagnostic diagrams:...

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