Ventos de gás ionizado a partir do núcleo da galáxia OH megamaser IRAS 09320+6134

Abstract

[Ultra]luminous infrared galaxies are extremely bright objects in this spectrum range, with luminosities bigger than 1011 L . It is observed that these objects, which typically consist of interactions and mergers of galaxies, are propitious environments for the emission of OH megamasers, luminous and powerful extragalactic masers. Although there is still no complete understanding of the physical conditions of the environments that produce OH megamasers, it is observed that many host systems of this phenomenon present a composite spectrum, both with characteristics associated with regions of intense star formation, the Starbursts, and with the presence of an AGN. The galaxy IRAS 09320+6134 is part of a project whose general objective is to relate the properties of the megamaser emission and the merger stage of its host galaxy with possible AGN and/or SB activities, in order to better understand the nature of the ionization mechanism of galaxies that present this phenomenon. The observations were performed on the Gemini North telescope, using the GMOS spectrograph, in IFU mode. IRAS 09320+6134 is on the boundary between LIRG and ULIRG, with an estimated infrared luminosity of LIR = 1011.95−12.02 L . We adjusted the emission lines present in the spectra by Gauss-Hermite series, however we observed that the gas kinematics had two components, so we made a new adjustment with two Gaussian curves, one narrow and one broad, to represent the profiles of the emission lines. From the adjustments, maps of flux, velocity and velocity dispersion were constructed, in addition to diagnostic diagrams and line intensity ratio maps. The flux distributions show extended emission in all lines in both components, with the emission of the narrow component being observed in the whole field of view and the emission of the broad component seen mainly in the central 1.5 00. The narrow component is tracing gas emission in the galaxy’s disk, and the velocity fields of this component show a rotating disk, with amplitudes up to ∼ 200 km s−1 . On the other hand, the broad component, seen in blueshift in relation to the narrow component, presents negative velocities of up to ∼ −800 km s−1 and is interpreted as being due to an outflow of ionized gas from the galaxy’s nucleus. The BPT and WHAN diagnostic diagrams for both components indicate that the ionization is predominantly due to the presence of an AGN. Preliminary estimates of the outflow properties indicate that its kinetic power is around 2 orders of magnitude less than the values estimated by cosmological simulations for the AGN feedback to be efficient in suppressing star formation. Finally, we also present an overview with preliminary results for another six galaxies of the sample, whose results have not been published yet. All objects show extended emission in the most intense emission lines and a rotating disk component. Furthermore, all objects present non-circular movements that cannot be represented by a rotating disk component alone, which will be better analyzed in a future work.