Extinction in the 11.2 μm PAH band and the low L11.2/LIRin ULIRGs

Autor: Dimitra Rigopoulou, Pablo G. Pérez-González, H. W. W. Spoon, Antonio Hernán-Caballero, Georgios E. Magdis, Almudena Alonso-Herrero, Miguel Pereira-Santaella, Alvaro Labiano, Isabella Cortzen, Evanthia Hatziminaoglou, Santiago Arribas, Javier Piqueras
Přispěvatelé: Magdis, G. E. [0000-0002-4872-2294], Cortzen, I. [0000-0001-9197-7623], National Aeronautics & Space Administration (NASA), Ministerio de Ciencia e Innovación (MICINN), MCIU/AEI/FEDER, Comunidad de Madrid through the Atracción de Talento Investigador Grant, Villum Fonden, Danish National Research Foundation, Comunidad de Madrid, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, National Aeronautics and Space Administration (NASA), Agencia Estatal de Investigación (AEI), Danish National Research Foundation (DNRF)
Rok vydání: 2020
Předmět:
Zdroj: Hernan-Caballero, A, Spoon, H W W, Alonso-Herrero, A, Hatziminaoglou, E, Magdis, G E, Perez-Gonzalez, P G, Pereira-Santaella, M, Arribas, S, Cortzen, I, Labiano, A, Piqueras, J & Rigopoulou, D 2020, ' Extinction in the 11.2 mu m PAH band and the low L 11.2 /L IR in ULIRGs ', Monthly Notices of the Royal Astronomical Society, vol. 497, no. 4, pp. 4614-4625 . https://doi.org/10.1093/mnras/staa2282
Hernan-Caballero, A, Spoon, H W W, Alonso-Herrero, A, Hatziminaoglou, E, Magdis, G E, Perez-Gonzalez, P G, Pereira-Santaella, M, Arribas, S, Cortzen, I, Labiano, A, Piqueras, J & Rigopoulou, D 2020, ' Extinction in the 11.2 mu m PAH band and the low L-11.2/L-IR in ULIRGs ', Monthly Notices of the Royal Astronomical Society, vol. 497, no. 4, pp. 4614-4625 . https://doi.org/10.1093/mnras/staa2282
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DOI: 10.1093/mnras/staa2282
Popis: We present a method for recovering the intrinsic (extinction-corrected) luminosity of the 11.2 micron 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 micron PAH bands is independent on the optical depth, with small dispersion of ~5% 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 the optical depth. 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 micron 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/L_sun = 10^9--10^13. These results consolidate L_11.2 as a robust tracer of star formation in galaxies.
Comment: 14 pages, 9 figures, 2 tables. Accepted for publication in MNRAS
Databáze: OpenAIRE
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