We present a multi-wavelength integral field spectroscopic (IFS) study of the low-z luminous infrared galaxy IRAS F11506-3851 (ESO 320-G030) on the basis of the moderate spectral resolution observations (R ∼ 3400−4000) taken with the VIMOS and SINFONI instruments at the ESO VLT. The morphology and the 2D kinematics of the gaseous (neutral and ionized) and stellar components have been mapped in the central regions (<3 kpc) using the NaDλλ5890, 5896 Å absorption doublet, the Hαλ6563 Å line, and the near-IR CO(2-0)λ2.293 µm and CO(3-1)λ2.322 µm bands. The kinematics of the ionized gas and the stars are dominated by rotation, with large observed velocity amplitudes (∆V(Hα) = 203 ± 4 km s −1 ; ∆V(CO) = 188 ± 11 km s −1 , respectively) and centrally peaked velocity dispersion maps (σ c (Hα) = 95 ± 4 km s −1 and σ c (CO) = 136 ± 20 km s −1 ). The stars lag behind the warm gas and represent a dynamically hotter system, as indicated by the observed V/σ ratios (4.5 and 2.4 for the gas and the stars, respectively). Thanks to these IFS data we have disentangled the contribution of the stars and the interstellar medium to the NaD feature, finding that it is dominated by absorption of neutral gas clouds in the interstellar medium (∼2/3 of total EW). The 2D kinematics of the neutral gas shows a complex structure dominated by two main components. On the one hand, the thick slowly rotating disk (∆V(NaD) = 81 ± 12 km s −1 ) lags significantly compared to the ionized gas and the stars, and it has an irregular and off-center velocity dispersion map (with values of up to ∼150 km s −1 at ∼1 kpc from the nucleus). On the other hand, a kpc-scale neutral gas outflow perpendicular to the disk, as is revealed by the large blueshifted velocities (in the range 30−154 km s −1 ) observed along the galaxy's semi-minor axis (within the inner 1.4 kpc). On the basis of a simple free wind scenario, we derive an outflowing mass rate (Ṁ w ) in neutral gas of about 48 M yr −1 . Although this implies a global mass loading factor (i.e., η =Ṁ w /SFR) of ∼1.4, the 2D distribution of the ongoing SF as traced by the Hα emission map suggests a much larger value of η associated with the inner regions (R < 200 pc), where the current observed star formation (SF) represents only ∼3 percent of the total. However, the relatively strong emission by supernovae in the central regions, as traced by the [FeII] emission, indicates recent strong episodes of SF. Therefore, our data show clear evidence of the presence of a strong outflow with large loading factors associated with the nuclear regions, where recent starburst activity took place about 7 Myr ago, although it currently shows relatively modest SF levels. All together these results strongly suggest that we are witnessing (nuclear) quenching due to SF feedback in IRAS F11506-3851. However, the relatively large mass of molecular gas detected in the nuclear region via the H 2 1−0S(1) line suggests that further episodes of SF may take place again.

We investigate the two-dimensional excitation structure of the interstellar medium (ISM) in a sample of luminous infrared galaxies (LIRGs) and Seyferts using near-IR integral field spectroscopy. This study extends to the near infrared the well-known optical and mid-IR emission line diagnostics used to classify activity in galaxies. Based on the spatially resolved spectroscopy of prototypes, we identify in the [FeII]1.64 µm/Brγ − H 2 2.12 µm/Brγ plane regions dominated by the different heating sources, i.e. active galactic nuclei (AGNs), young main-sequence massive stars, and evolved stars i.e. supernovae. The ISM in LIRGs occupy a wide region in the near-IR diagnostic plane from −0.6 to +1.5 and from −1.2 to +0.8 (in log units) for the [FeII]/Brγ and H 2 /Brγ line ratios, respectively. The corresponding median(mode) ratios are +0.18(0.16) and +0.02(−0.04). Seyferts show on average larger values by factors ∼2.5 and ∼1.4 for the [FeII]/Brγ and H 2 /Brγ ratios, respectively. New areas and relations in the near-IR diagnostic plane are defined for the compact, high surface brightness regions dominated by AGN, young ionizing stars, and supernovae explosions, respectively. In addition to these high surface brightness regions, the diffuse regions affected by the AGN radiation field cover an area similar to that of Seyferts, but with high values in [FeII]/Brγ that are not as extreme. The extended, non-AGN diffuse regions cover a wide area in the near-IR diagnostic diagram that overlaps that of individual excitation mechanisms (i.e. AGN, young stars, and supernovae), but with its mode value to that of the young star-forming clumps. This indicates that the excitation conditions of the extended, diffuse ISM are likely due to a mixture of the different ionization sources, weighted by their spatial distribution and relative flux contribution. The integrated line ratios in LIRGs show higher excitation conditions i.e. towards AGNs, than those measured by the spatially resolved spectroscopy. If this behaviour is representative, it would have clear consequences when classifying high-z, star-forming galaxies based on their near-infrared integrated spectra.

We analyze new high spatial resolution (∼60 pc) ALMA CO(2-1) observations of the isolated luminous infrared galaxy ESO 320-G030 (d = 48 Mpc) in combination with ancillary HST optical and near-IR imaging as well as VLT/SINFONI near-IR integral field spectroscopy. We detect a high-velocity (∼450 km s −1 ) spatially resolved (size∼2.5 kpc; dynamical time ∼3 Myr) massive (∼10 7 M ;Ṁ ∼2-8 M yr −1 ) molecular outflow originated in the central ∼250 pc. We observe a clumpy structure in the outflowing cold molecular gas with clump sizes between 60 and 150 pc and masses between 10 5.5 and 10 6.4 M . The mass of the clumps decreases with increasing distance, while the velocity is approximately constant. Therefore, both the momentum and kinetic energy of the clumps decrease outwards. In the innermost (∼100 pc) part of the outflow, we measure a hot-to-cold molecular gas ratio of 7×10 −5 , which is similar to that measured in other resolved molecular outflows. We do not find evidence of an ionized phase in this outflow. The nuclear IR and radio properties are compatible with strong and highly obscured star-formation (A k ∼ 4.6 mag; SFR ∼ 15 M yr −1 ). We do not find any evidence for the presence of an active galactic nucleus. We estimate that supernova explosions in the nuclear starburst (νSN ∼ 0.2 yr −1 ) can power the observed molecular outflow. The kinetic energy and radial momentum of the cold molecular phase of the outflow correspond to about 2% and 20%, respectively, of the supernovae output. The cold molecular outflow velocity is lower than the escape velocity, so the gas will likely return to the galaxy disk. The mass loading factor is ∼0.1-0.5, so the negative feedback due to this star-formation powered molecular outflow is probably limited.

We present new CO(2-1) observations of three low-z (d ∼350 Mpc) ULIRG systems (6 nuclei) observed with ALMA at high-spatial resolution (∼500 pc). We detect massive cold molecular gas outflows in 5 out of 6 nuclei (M out ∼ (0.3 − 5) × 10 8 M ). These outflows are spatially resolved with deprojected effective radii between 250 pc and 1 kpc although high-velocity molecular gas is detected up to R max ∼ 0.5 − 1.8 kpc (1 − 6 kpc deprojected). The mass outflow rates are 12 − 400 M yr −1 and the inclination corrected average velocity of the outflowing gas 350 − 550 km s −1 (v max = 500 − 900 km s −1 ). The origin of these outflows can be explained by the strong nuclear starbursts although the contribution of an obscured AGN can not be completely ruled out. The position angle (PA) of the outflowing gas along the kinematic minor axis of the nuclear molecular disk suggests that the outflow axis is perpendicular to the disk for three of these outflows. Only in one case, the outflow PA is clearly not along the kinematic minor axis and might indicate a different outflow geometry. The outflow depletion times are 15 − 80 Myr. These are comparable to, although slightly shorter than the star-formation (SF) depletion times (30 − 80 Myr). However, we estimate that only 15 − 30% of the outflowing molecular gas will escape the gravitational potential of the nucleus. The majority of the outflowing gas will return to the disk after 5−10 Myr and become available to form new stars. Therefore, these outflows will not likely completely quench the nuclear starbursts. These star-forming powered molecular outflows would be consistent with being driven by radiation pressure from young stars (i.e., momentum-driven) only if the coupling between radiation and dust increases with increasing SF rates. This can be achieved if the dust optical depth is higher in objects with higher SF. This is the case in, at least, one of the studied objects. Alternatively, if the outflows are mainly driven by supernovae (SNe), the coupling efficiency between the interstellar medium and SNe must increase with increasing SF levels. The relatively small sizes (<1 kpc) and dynamical times (<3 Myr) of the cold molecular outflows suggests that molecular gas cannot survive longer in the outflow environment or that it cannot form efficiently beyond these distances or times. In addition, the ionized and hot molecular phases have been detected for several of these outflows, so this suggests that outflowing gas can experience phase changes and indicates that the outflowing gas is intrinsically multiphase, likely sharing similar kinematics, but different mass and, therefore, energy and momentum contributions.