Proyecto de Investigación: AYA2015-63650-P
Cargando...
Colaboradores
Financiadores
ID
AYA2015-63650-P
Autores
Publicaciones
Molecular clouds in the Cosmic Snake normal star-forming galaxy 8 billion years ago
(Nature Research Journals, 2019-09-16) Dessauges Zavadsky, M.; Richard, J.; Combes, F.; Schaerer, D.; Rujopakarn, W.; Mayer, L.; Cava, A.; Boone, F.; Egami, E.; Kneib, J. P.; Pérez González, P. G.; Pfenniger, D.; Rawle, T. D.; Teyssier, R.; Van der Werf, P. P.; Copyright © 2019, The Author(s), under exclusive licence to Springer Nature Limited; European Research Council (ERC); Ministerio de Economía y Competitividad (MINECO); Combes, F. [0000-0003-2658-7893]; Van der Werf, P. [0000-0001-5434-5942]; Kneib, J. P. [0000-0002-4616-4989]; Pfenniger, D. [0000-0002-0980-3622]; Rawle, T. [0000-0002-7028-5588]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with 10(4)-10(7) solar masses (M-circle dot) and radii of 5-100 parsecs, are the seeds of star formation(1). Highlighting the molecular gas structure at such small scales in distant galaxies is observationally challenging. Only a handful of molecular clouds were reported in two extreme submillimetre galaxies at high redshift(2-4). Here we search for GMCs in a typical Milky Way progenitor at z = 1.036. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we mapped the CO(4-3) emission of this gravitationally lensed galaxy at high resolution, reading down to 30 parsecs, which is comparable to the resolution of CO observations of nearby galaxies(5). We identify 17 molecular clouds, characterized by masses, surface densities and supersonic turbulence all of which are 10-100 times higher than present-day analogues. These properties question the universality of GMCs(6) and suggest that GMCs inherit their properties from ambient interstellar medium. The measured cloud gas masses are similar to the masses of stellar clumps seen in the galaxy in comparable numbers(7). This corroborates the formation of molecular clouds by fragmentation of distant turbulent galactic gas disks(8,9), which then turn into stellar clumps ubiquitously observed in galaxies at 'cosmic noon' (ref.(10).
The structural properties of classical bulges and discs from z ∼ 2
(Oxford Academics: Oxford University Press, 2019-09-02) Dimauro, P.; Huertas Company, M.; Daddi, E.; Pérez González, P. G.; Bernardi, M.; Caro, F.; Cattaneo, A.; Häubler, B.; Kuchner, U.; Shankar, F.; Barro, G.; Buitrago, F.; Faber, S. M.; Kocevski, D. D.; Koekemoer, A. M.; Koo, D. C.; Mei, S.; Peletier, R.; Primack, J.; Rodríguez Puebla, A.; Salvato, M.; Tuccillo, D.; Ministerio de Economía y Competitividad (MINECO); Salvato, M. [https://orcid.org/0000-0001-7116-9303]; Buitrago, F. [https://orcid.org/0000-0002-2861-9812]; Daddi, E. [https://orcid.org/0000-0002-3331-9590]; Peletier, R. [https://orcid.org/0000-0001-7621-947X]; Huertas Company, M. [https://orcid.org/0000-0002-1416-8483]
We study the rest-frame optical mass–size relation of bulges and discs from z ∼ 2 to z ∼ 0 for a complete sample of massive galaxies in the CANDELS fields using two-component Sérsic models. Discs and star-forming galaxies follow similar mass–size relations. The mass–size relation of bulges is less steep than the one of quiescent galaxies (best-fitting slope of 0.7 for quiescent galaxies against 0.4 for bulges). We find little dependence of the structural properties of massive bulges and discs with the global morphology of galaxies (disc versus bulge dominated) and the star formation activity (star-forming versus quiescent). This result suggests similar bulge formation mechanisms for most massive galaxies and also that the formation of the bulge component does not significantly affect the disc structure. Our results pose a challenge to current cosmological models that predict distinct structural properties for stellar bulges arising from mergers and disc instabilities.
Extinction in the 11.2 mu m PAH band and the low L-11.2/L-IR in ULIRGs
(Oxford Academics: Blackwell Publishing, 2020-08-05) Hernández Caballero, A.; Spoon, H. W. W.; Alonso Herrero, A.; Hatziminaoglou, Evanthia; Magdis, Georgios E.; Pérez González, P. G.; Pereira Santaella, M.; Arribas, S.; Cortzen, I.; Labiano, Á.; Piqueras, J.; Rigopoulou, D.; National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); Villum Fonden; Danish National Research Foundation (DNRF); Comunidad de Madrid; 0000-0002-4872-2294; 0000-0001-9197-7623; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present a method for recovering the intrinsic (extinction-corrected) luminosity of the 11.2 mu m PAH band in galaxy spectra. Using 105 high S/N Spitzer/IRS spectra of star-forming galaxies, we show that the equivalent width ratio of the 12.7 and 11.2 mu m PAH bands is independent on the optical depth (tau), with small dispersion (similar to 5 percent) indicative of a nearly constant intrinsic flux ratio R-int = (f(12.7)/f(11.2))(int) = 0.377 +/- 0.020. Conversely, the observed flux ratio, R-obs = (f(12.7)/f(11.2))(obs), strongly correlates with the silicate strength (S-sil) confirming that differences in R-obs reflect variation in tau. The relation between R-obs and S-sil reproduces predictions for the Galactic Centre extinction law but disagrees with other laws. We calibrate the total extinction affecting the 11.2 mu m PAH from R-obs, which we apply to another sample of 215 galaxies with accurate measurements of the total infrared luminosity (L-IR) to investigate the impact of extinction on L-11.2/L-IR. Correlation between L-11.2/L-IR and R-obs independently on L-IR suggests that increased extinction explains the well-known decrease in the average L-11.2/L-IR at high L-IR. The extinction-corrected L-11.2 is proportional to L-IR in the range L-IR = 10(9)-10(13) L-circle dot. These results consolidate L-11.2 as a robust tracer of star formation in galaxies.
