arXiv subjects

D. Kakkad

Publications and source records attributed to D. Kakkad.

39 records · Page 3Linked to original sources

arXiv2016

Tracing outflows in the AGN forbidden region with SINFONI

AGN driven outflows are invoked in numerical simulations to reproduce several observed properties of local galaxies. The z > 1 epoch is of particular interest as it was during this time that the volume averaged star formation and the accretion rate of black holes were maximum. Radiatively driven outflows are therefore believed to be common during this epoch. We aim to trace and characterize outflows in AGN hosts with high mass accretion rates at z > 1 using integral field spectroscopy. We obtain spatially-resolved kinematics of the [OIII]5007 line in two targets which reveal the morphology and spatial extension of the outflows. We present J and H+K band SINFONI observations of 5 AGNs at 1.2 < z < 2.2. To maximize the chance of observing radiatively driven outflows, our sample was pre-selected based on peculiar values of the Eddington ratio and the hydrogen column density of the surrounding interstellar medium. We observe high velocity (~600-1900 km/s) and kiloparsec scale extended ionized outflows in at least 3 of our targets, using [OIII]5007 line kinematics tracing the AGN narrow line region. We estimate the total mass of the outflow, the mass outflow rate, and the kinetic power of the outflows based on theoretical models and report on the uncertainties associated with them. We find mass outflow rates of ~1-10 M_sun/yr for the sample presented in this paper. Based on the high star formation rates of the host galaxies, the observed outflow kinetic power and the expected power due to the AGN, we infer that both star formation and AGN radiation could be the dominant source for the outflows. The outflow models suffer from large uncertainties, hence we call for further detailed observations for an accurate determination of the outflow properties to confirm the exact source of these outflows.

astro-ph.GA↗

arXiv2016

Large-scale outflows in luminous QSOs revisited: The impact of beam smearing on AGN feedback efficiencies

[Abridged] Enormous observational efforts have been made to constrain the energetics of AGN feedback by mapping the kinematics of the ionized gas on kpc scale. We study how the observed kinematics and inferred energetics are affected by beam smearing of a bright unresolved NLR due to seeing. We analyse IFU spectroscopy of a sample of twelve QSOs initially presented by Liu et al. (2014). The PSF for the observations is directly obtained from the light distribution of the broad Hb line component. We are able to compare the ionized gas kinematics and derived energetics of the total, spatially extended, and unresolved [OIII] emission. We find that the spatially resolved [OIII] line width on kpc scales is significantly narrower than the one before PSF deblending. The ENLRs appear offset from the QSO position or more elongated which can be interpreted in favour of a conical outflow on large scales while a spherical geometry cannot be excluded for the unresolved NLR. We find that the kinetic power at 5kpc distance from the spherical model by Liu et al. (2013) is reduced by two magnitudes for a conical outflow and one magnitude for the unresolved NLR after PSF deblending. This reduced kinetic power corresponds to 0.01-0.1% of the bolometric AGN luminosity. This is smaller than the 5-10% feedback efficiency required by some simulations to reproduce the massive galaxy population. The injected momentum fluxes are close or below the simple radiation-pressure limit Lbol/c for the conical outflow model for the NLR and ENLR when beam smearing is considered. IFU spectroscopy is a powerful tool to investigate the energetics of AGN outflows, but the impact of beam smearing has to be taken into account. For the majority of observations in the literature, this has not been addressed carefully so that the incidence and energetics of presumed kpc-scale AGN-driven outflows still remain an unsolved issue.

astro-ph.GA↗

arXiv2016

A fast ionised wind in a Star Forming-Quasar system at z~1.5 resolved through Adaptive Optics assisted near-infrared data

Outflows are invoked in co-evolutionary models to link the growth of SMBH and galaxies through feedback phenomena, and from the analysis of both galaxies and Active Galactic Nuclei (AGN) samples at z$\sim1-3$, it is becoming clear that powerful winds are quite common in AGN hosts. High-resolution and high S/N observations are needed in order to uncover the physical properties of the wind through kinematics analysis. We exploited VIMOS, SINFONI and Subaru/IRCS Adaptive Optics data to study the kinematics properties on the scale the host galaxy of XID5395, a luminous, X-ray obscured Starburst/Quasar merging system at z$\sim1.5$ detected in the XMM-COSMOS field, and associated with an extreme [O II] emitter (EW$\sim200$ Å). We mapped, for the first time, at high resolution the kinematics of the [O III] and H$α$ line complexes and linked them with the [O II] emission. The high spatial resolution achieved allowed us to resolve all the components of the SB-QSO system. Our analysis with a resolution of few kpc reveals complexities and asymmetries in and around the nucleus of XID5395. The velocity field measured via non parametric analysis reveals different kinematic components, with maximum blueshifted and redshifted velocities up to $\simeq1300$ km s$^{-1}$, not spatially coincident with the nuclear core. These extreme values of the observed velocities and the spatial location can be explained by the presence of fast moving material. We also spectroscopically confirm the presence of a merging system at the same redshift of the AGN host. We propose that EW as large as $>150$ Å in X-ray selected AGN may be an efficient criterion to isolate objects associated to the short, transition phase of "feedback" in the AGN-galaxy co-evolutionary path, which will subsequently evolve in an unobscured QSO, as suggested from the different observational evidences we accumulated for XID5395.

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