Optical integral field spectroscopy of intermediate redshift infrared bright galaxies

Pereira Santaella, M., Rigopoulou, D., Magdis, G. E., Thatte, N., Alonso Herrero, A., Clarke, F., Farrah, D., García Burillo, S., Hogan, L., Morris, S., Rodrígues, M., Huang, J. S., Tecza, M. 2019. Optical integral field spectroscopy of intermediate redshift infrared bright galaxies. Monthly Notices of the Royal Astronomical Society 486, 4, 5621-5645 DOI: 10.1093/mnras/stz1218

The extreme infrared (IR) luminosity of local luminous and ultraluminous IR galaxies (11/LIRGs; 11 < log LIR/LE:, < 12 and log LIR /L.> 12., respectively) is mainly powered by star formation processes triggered by mergers or interactions. While INLIRGs are rare locally, at z > 1, they become more common, dominate the star formation rate (SFR) density, and a fraction of them are found to be normal disc galaxies. Therefore, there must be an evolution of the mechanism triggering these intense starbursts with redshift. To investigate this evolution, we present new optical swit,r integral field spectroscopic H cx + [N n] observations of a sample of nine intermediate-z (0.2 < z < 0.4) INEIRG systems selected from Herschel 250 p.m observations. The main results are the following: (a) the ratios between the velocity dispersion and the rotation curve amplitude indicate that 10-25 per cent (1-2 of 8) might be compatible with being isolated discs, while the remaining objects are interactinghnerging systems; (b) the ratio between un-obscured and obscured SFR traced by H cz and LIR, respectively, is similar in both local and these intermediate-z Ll/LIRGs; and (c) the ratio between 250 p.im and the total IR luminosities of these intermediate-z INEIRGs is-higher than that of local INLIRGs with the same LIR, This indicates a reduced dust temperature in these intermediate-z INLIRGs. This, together with their already measured enhanced molecular gas content, suggests that the interstellar medium conditions are different in our sample of intermediate-z galaxies when compared to local II/LIRGs.

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