Examinando por Autor "Cortzen, I."

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Acceso Abierto
A Complete 16 μm Selected Galaxy Sample at z ∼ 1: Mid-infrared Spectral Energy Distributions
(IOP Science Publishing, 2021-05-28) Huang, J. S.; Dai, Y. S.; Willner, S. P.; Faber, S. M.; Cheng, C.; Xu, H.; Yan, H.; Wu, S.; Shao, X.; Hao, C.; Xia, X.; Rigopoulou, D.; Pereira Santaella, M.; Magdis, Georgios E.; Cortzen, I.; Fazio, G. G.; Assmann, P.; Fan, L.; Musin, M.; Zang, Z.; Xu, K. C.; He, C.; Jin, G.; Esamdin, A.; National Natural Science Foundation of China (NSFC); Chinese Academy of Sciences (CAS); Danish National Research Foundation (DNRF); Science and Technology Facilities Council (STFC); South America Center for Astronomy (CASSACA); Huang, J. S. [0000-0001-6511-8745]; Dai, Y. S. [0000-0002-7928-416X]; Willner, S. P. [0000-0002-9895-5758]; Faber, S. M. [0000-0003-4996-214X]; Cheng, C. [0000-0003-0202-0534]; Yan, H. [0000-0001-7592-7714]; Rigopoulou, D. [0000-0001-6854-7545]; Pereira Santaella, M. [0000-0002-4005-9619]; Magdis, G. [0000-0002-4872-2294]; Cortzen, I. [0000-0001-9197-7623]; Fazio, G. G. [0000-0002-0670-0708]; Fan, L. [0000-0003-4200-4432]; Jin, G. [0000-0003-3087-318X]; Esamdin, A. [0000-0003-1845-4900]
We describe a complete, flux-density-limited sample of galaxies at redshift 0.8 < z < 1.3 selected at 16 μm. At the selection wavelength near 8 μm rest, the observed emission comes from both dust heated by intense star formation and active galactic nuclei (AGNs). Fitting the spectral energy distributions (SEDs) of the sample galaxies to local-galaxy templates reveals that more than half the galaxies have SEDs dominated by star formation. About one-sixth of the galaxy SEDs are dominated by an AGN, and nearly all of the rest of the SEDs are composite. Comparison with X-ray and far-infrared observations shows that combinations of luminosities at rest-frame 4.5 and 8 μm give good measures of both AGN luminosity and star formation rate. The sample galaxies mostly follow the established star-forming main sequence for z = 1 galaxies, but of the galaxies more than 0.5 dex above that main sequence, more than half have AGN-type SEDs. Similarly, the most luminous AGNs tend to have higher star formation rates than the main-sequence value. Galaxies with stellar masses >1011 M⊙ are unlikely to host an AGN. About 1% of the sample galaxies show an SED with dust emission typical of neither star formation nor an AGN.
Restringido
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.