2021A&A...645A..49G -
Astronomy and Astrophysics, volume 645A, 49-49 (2021/1-1)
A proto-pseudobulge in ESO 320-G030 fed by a massive molecular inflow driven by a nuclear bar.
GONZALEZ-ALFONSO E., PEREIRA-SANTAELLA M., FISCHER J., GARCIA-BURILLO S., YANG C., ALONSO-HERRERO A., COLINA L., ASHBY M.L.N., SMITH H.A., RICO-VILLAS F., MARTIN-PINTADO J., CAZZOLI S. and STEWART K.P.
Abstract (from CDS):
Galaxies with nuclear bars are believed to efficiently drive gas inward, generating a nuclear starburst and possibly an active galactic nucleus. We confirm this scenario for the isolated, double-barred, luminous infrared galaxy ESO 320-G030 based on an analysis of Herschel and ALMA spectroscopic observations. Herschel/PACS and SPIRE observations of ESO 320-G030 show absorption or emission in 18 lines of H2O, which we combine with the ALMA H2O 423-330 448GHz line (Eupper∼400K) and continuum images to study the physical properties of the nuclear region. Radiative transfer models indicate that three nuclear components are required to account for the multi-transition H2O and continuum data. An envelope, with radius R∼130-150pc, dust temperature Tdust≃50K, and NH2∼2x1023cm–2, surrounds a nuclear disk with R∼40pc that is optically thick in the far-infrared (τ100µm∼1.5-3, NH2∼2x1024cm–2). In addition, an extremely compact (R∼12pc), warm (≃100K), and buried (τ100µm>5, NH2≥5x1024cm–2) core component is required to account for the very high-lying H2O absorption lines. The three nuclear components account for 70% of the galaxy luminosity (SFR∼16-18M☉/yr). The nucleus is fed by a molecular inflow observed in CO 2-1 with ALMA, which is associated with the nuclear bar. With decreasing radius (r=450-225pc), the mass inflow rate increases up to Minf∼20M/yr, which is similar to the nuclear star formation rate (SFR), indicating that the starburst is sustained by the inflow. At lower r, ∼100-150pc, the inflow is best probed by the far-infrared OH ground-state doublets, with an estimated Minf∼30M/yr. The inferred short timescale of ∼20Myr for nuclear gas replenishment indicates quick secular evolution, and indicates that we are witnessing an intermediate stage (<100Myr) proto-pseudobulge fed by a massive inflow that is driven by a strong nuclear bar. We also apply the H2O model to the Herschel far-infrared spectroscopic observations of H218O, OH, 18OH, OH+, H2O+, H3O+, NH, NH2, NH3, CH, CH+, 13CH+, HF, SH, and C3, and we estimate their abundances.
Abstract Copyright:
© ESO 2021
Journal keyword(s):
galaxies: bulges - galaxies: clusters: individual: ESO 320-G030 - galaxies: evolution - galaxies: nuclei - infrared: galaxies - submillimeter: galaxies
Simbad objects:
16
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