arXiv subjects

Cristina Ramos Almeida

Publications and source records attributed to Cristina Ramos Almeida.

At least 55 records · Page 3Linked to original sources

arXiv2024

The miniJPAS Survey: The radial distribution of star formation rates in faint X-ray active galactic nuclei

We study the impact of black hole nuclear activity on both the global and radial star formation rate (SFR) profiles in X-ray-selected active galactic nuclei (AGN) in the field of miniJPAS, the precursor of the much wider J-PAS project. Our sample includes 32 AGN with z < 0.3 detected via the XMM-Newton and Chandra surveys. For comparison, we assembled a control sample of 71 star-forming (SF) galaxies with similar magnitudes, sizes, and redshifts. To derive the global properties of both the AGN and the control SF sample, we used CIGALE to fit the spectral energy distributions derived from the 56 narrowband and 4 broadband filters from miniJPAS. We find that AGN tend to reside in more massive galaxies than their SF counterparts. After matching samples based on stellar mass and comparing their SFRs and specific SFRs (sSFRs), no significant differences appear. This suggests that the presence of AGN does not strongly influence overall star formation. However, when we used miniJPAS as an integral field unit (IFU) to dissect galaxies along their position angle, a different picture emerges. We find that AGN tend to be more centrally concentrated in mass with respect to SF galaxies. Moreover, we find a suppression of the sSFR up to 1Re and then an enhancement beyond 1Re , strongly contrasting with the decreasing radial profile of sSFRs in SF galaxies. This could point to an inside-out quenching of AGN host galaxies. These findings suggest that the reason we do not see differences on a global scale is because star formation is suppressed in the central regions and enhanced in the outer regions of AGN host galaxies. While limited in terms of sample size, this work highlights the potential of the upcoming J-PAS as a wide-field low-resolution IFU for thousands of nearby galaxies and AGN.

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arXiv2024

A study of interacting galaxies from the Arp-Madore Catalogue: Triggering of star formation and nuclear activity

We present Gemini Multi-Object Spectrograph (GMOS) spectroscopic observations of 95 galaxies from the Arp & Madore (1987) catalogue of peculiar galaxies. These galaxies have been selected because they appear to be in pairs and small groups. These observations have allowed us to confirm that 60 galaxies are indeed interacting systems. For the confirmed interacting sample, we have built a matched control sample of isolated galaxies. We present an analysis of the stellar populations and nuclear activity in the interacting galaxies and compare them with the isolated galaxies. We find a median light (mass) fraction of 55% (10%) in the interacting galaxies coming from stellar populations younger than 2 Gyr and 28% (3%) in the case of the isolated galaxies. More than half of the interacting galaxies are dominated by this young stellar population, while the isolated ones have most of their light coming from older stellar populations. We used a combination of diagnostic diagrams (BPTs and WHAN) to classify the main ionization mechanisms of the gas. The interacting galaxies in our sample consistently show a higher fraction of active galactic nuclei (AGN) relative to the control sample, which ranges between 1.6 and 4 depending on the combination of diagnostic diagrams employed to classify the galaxies and the number of galaxies considered. Our study provides further observational evidence that interactions drive star formation and nuclear activity in galaxies and can have a significant impact on galaxy evolution.

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arXiv2024

A 20 kiloparsec bipolar Lyman $α$ outflow from a radio galaxy at z=2.95

The study of ionized gas kinematics in high-z active galaxies plays a key part in our understanding of galactic evolution, in an age where nuclear activity was widespread and star formation close to its peak. We present a study of TXS 0952-217, a radio galaxy at z=2.95, using VLT/MUSE integral field optical spectroscopy as part of a project aimed studying of the properties of ionized gas in high redshift radio galaxies (HzRGs). The Lyman $α$ line profile of this object presents various emission and absorption components. By utilizing Voronoi binning, we obtained a comprehensive map of the kinematic properties of these components. These observations revealed the presence of a redshifted, high velocity (v $\sim 500$ km s$^-1$) bipolar structure of Lyman $α$ emission, most likely corresponding to an outflow of ionized gas. The outflow extends beyond the compact radio source on both sides, with a total size of $\sim$ 21 kpc. Its kinetic power ($10^{42.1}$ erg s$^{-1}$) is about five orders of magnitude smaller than its radio power. Additional ionized lines, including HeII$λ$1640, CIV$λ$1550 and CIII]$λ$1908 were detected and their line flux ratios determined. The presence of HeII allowed for a precise redshift measurement (z=2.945$\pm$0.002). Along with the recent discovery of a similar structure in TN J1049-1258, another HzRG, it displays the feasibility of using Lyman $α$ as a tracer of outflowing gas in high redshift sources, and particularly so when supported by non-resonant ionized lines such as HeII, which allow for accurate redshift and velocity measurements.

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arXiv2024

QSOFEED: The relationship between star formation and AGN Feedback

Large-scale cosmological simulations suggest that feedback from active galactic nuclei (AGN) plays a crucial role in galaxy evolution. In this study, we directly test this hypothesis utilising SDSS spectra of a sample of 48 low redshift (z<0.14) type 2 quasars (QSO2s). We characterised the kinematics of the warm ionised gas by performing a non-parametric analysis of the [OIII]$λ5007$ emission line, as well as constrain the properties of the young stellar populations (YSP) of their host galaxies through spectral synthesis modelling. These analyses revealed that 85% of the QSO2s display gas velocity dispersions larger than that of the stellar component of their host galaxies, indicating the presence of AGN-driven outflows. Comparing the gas kinematics to the AGN properties, we found a positive correlation between gas velocity dispersion and 1.4 GHz radio luminosity but not with AGN bolometric luminosity or Eddington ratio, suggesting that, either the radio luminosity is the key factor in driving outflows or that the outflows themselves are shocking the ISM and producing synchrotron emission. We found that 98% of the sample host YSPs to varying degrees, with star formation rates (SFR) $0 \le SFR \le 92 \mbox{ M}_{\odot} \mbox{yr}^{-1}$, averaged over 100 Myr. We compared the gas kinematics and outflow properties to the SFRs to establish possible correlations which may suggest that the presence of the outflowing gas is impacting SF and find that none exists, leading to the conclusion that, on the scales probed by the SDSS fibre, AGN-driven outflows do not impact SF on the timescales probed in this study. However, we found a positive correlation between the light-weighted stellar ages of the QSO2s and the black hole mass, which may indicate that successive AGN episodes lead to the suppression of SF over the course of galaxy evolution.

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arXiv2024

Ionised AGN outflows in the Goldfish galaxy -- The illuminating and interacting red quasar eFEDSJ091157.4+014327 at z $\sim$ 0.6

Evolutionary models suggest that the initial growth phases of active galactic nuclei (AGN) are dust-enshrouded, and characterised by jet/wind outflows that should gradually clear the interstellar medium (ISM) in the host by heating and/or expelling the surrounding gas. eFEDSJ091157.4$+$014327 (z$\sim$0.6) was selected from X-ray samples for its characteristics that are similar to sources with outflows which include red, obscured and X-ray luminous. We aim to explore the environment around this red quasar and characterise kinematics within the system. We used spatially resolved spectroscopic data from Multi Unit Spectroscopic Explorer (MUSE) with an average seeing of 0.6" to construct flux, velocity and velocity dispersions maps. We found that the quasar is embedded in an interacting and merging system with three other galaxies $\sim$ 50 kpc from its nucleus. Spatially resolved kinematics reveal that the quasar has extended ionised outflows of up to 9.2 kpc with positive and negative velocities up to 1000 km s$^{-1}$ and -1200 km s$^{-1}$, respectively. The velocity dispersion (W$_{80}$) ranges from 600-1800 km s$^{-1}$. We associate the presence of turbulent and high-velocity components with the outflow. The total mass outflow rate is estimated to be $\sim$ 10 M$_{\odot}$ yr$^{-1}$ and kinetic power of 2x10$^{42}$ erg s$^{-1}$. The kinetic coupling efficiencies range from 0.01%-0.03% and the momentum boosts are $\sim$ 0.2. These low values indicate that the ionised outflow is not energetically relevant. These values don't align with the theoretical predictions of both radiation-pressure-driven outflows and energy-conserving mechanisms. However, note that our results are based only on the ionised phase while theoretical predictions are multiphase. Moreover, the mass loading factor of $\sim$ 5 is an indication that these outflows are more likely AGN-driven than star formation-driven.

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arXiv2024

Observational constraints on the stellar recycled gas in active galactic nuclei feeding

Near-infrared long-slit spectroscopy has been used to study the stellar population (SP) of the low luminosity active galactic nuclei (AGN) and matched analogues (LLAMA) sample. To perform the SP fits we have employed the X-shooter simple stellar population models together with the \st\ code. Our main conclusions are: The star formation history of the AGNs is very complex, presenting many episodes of star formation during their lifetimes. In general, AGN hosts have higher fractions of intermediate-age SP (light-weighted mean ages, $ _L\lesssim$ 4.5 Gyr) when compared with their analogues ($ _L\lesssim$ 8.0 Gyr). AGN are more affected by reddening and require significant fractions of featureless continuum and hot dust components. The ratio between the AGN radiated energy and the gravitational potential energy of the molecular gas ($E_{Rad}$/$E_{PG}$) for the AGN is compared with the \maL\ and a possible anti-correlation is observed. This suggests that the AGN is affecting the star formation in these galaxies, in the sense that more energetic AGN (log$(E_{Rad}$/$E_{PG}) \gtrsim 3$) tend to host nuclear younger SP ($ _L \lesssim$4Gyr). We found that the recent ($t<$2~Gyr) returned (recycled) stellar mass is higher in AGN than in the controls. We also provide evidence that the mass loss of stars would be enough to feed the AGN, thus providing observational constraints for models that predict that AGN feeding is partially due to the recycled gas from dying stars.

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arXiv2024

Observational Tests of Active Galactic Nuclei Feedback: An Overview of Approaches and Interpretation

Growing supermassive black holes (Active Galactic Nuclei; AGN) release energy with the potential to alter their host galaxies and larger-scale environment; a process named "AGN feedback". Feedback is a required component of galaxy formation models and simulations to explain observed properties of galaxy populations. We provide a broad overview of observational approaches that are designed to establish the physical processes that couple AGN energy to the multi-phase gas, or to find evidence that AGN impact upon galaxy evolution. The orders-of-magnitude range in spatial, temporal, and temperature scales, requires a diverse set of observational studies. For example, studying individual targets in detail sheds light on coupling mechanisms; however, evidence for long-term impact of AGN is better established within galaxy populations that are not necessarily currently active. We emphasise how modern surveys have revealed the importance of radio emission for identifying, and characterising, feedback mechanisms. At the achieved sensitivities, the detected radio emission can trace a range of processes, including shocked interstellar medium caused by AGN outflows (driven by various mechanisms including radiation pressure, accretion disc winds, and jets). We also describe how interpreting observations in the context of theoretical work can be challenging, in part, due to some of the adopted terminology.

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arXiv2024

ALMA reveals a compact and massive molecular outflow driven by the young AGN in a nearby ULIRG

The ultra luminous infrared galaxy (ULIRG) F13451+1232 is an excellent example of a galaxy merger in the early stages of active galactic nucleus (AGN) activity, a phase in which AGN-driven outflows are expected to be particularly important. However, previous observations have determined that the mass outflow rates of the warm ionised and neutral gas phases in F13451+1232 are relatively modest, and there has been no robust detection of molecular outflows. Using high spatial resolution ALMA CO(1-0) observations, we detect a kiloparsec-scale circumnuclear disk, as well as extended ($r\sim440$ pc), intermediate-velocity (300<|$v$|<400 km s$^{-1}$) cold molecular gas emission that cannot be explained by rotational disk motions. If interpreted as AGN-driven outflows, the mass outflow rates associated with this intermediate-velocity gas are relatively modest ($\dot{M}_\mathrm{out}=22$-$27$ M$_\odot$ yr$^{-1}$); however, we also detect a compact ($r_\mathrm{out}$<120 pc), high velocity (400<$v$<680 km s$^{-1}$) cold molecular outflow near the primary nucleus of F13451+1232, which carries an order of magnitude more mass ($\dot{M}_\mathrm{out}\sim230$ M$_\odot$ yr$^{-1}$) than (and several times the kinetic power of) the previously-detected warmer phases. Moreover, the similar spatial scales of this compact outflow and the radio structure indicate that it is likely accelerated by the small-scale ($r\sim130$ pc) AGN jet in the primary nucleus of F13451+1232. Considering the compactness of the nuclear outflow and intermediate-velocity non-rotating gas that we detect, we argue that high spatial-resolution observations are necessary to properly quantify the properties of AGN-driven outflows and their impacts on host galaxies.

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arXiv2024

Scrutinising evidence for the triggering of Active Galactic Nuclei in the outskirts of massive galaxy clusters at $z\approx1$

Environmental effects are believed to play an important yet poorly understood role in triggering accretion events onto the supermassive black holes (SMBHs) of galaxies (Active Galactic Nuclei; AGN). Massive clusters, which represent the densest structures in the Universe, provide an excellent laboratory to isolate environmental effects and study their impact on black hole growth. In this work, we critically review observational evidence for the preferential activation of SMBHs in the outskirts of galaxy clusters. We develop a semi-empirical model under the assumption that the incidence of AGN in galaxies is independent of environment. We demonstrate that the model is broadly consistent with recent observations on the AGN halo occupation at $z=0.2$, although it may overpredict satellite AGN in massive halos at that low redshift. We then use this model to interpret the projected radial distribution of X-ray sources around high redshift ($z\approx1$) massive ($>5 \times 10^{14} \, M_\odot$) clusters, which show excess counts outside their virial radius. Such an excess naturally arises in our model as a result of sample variance. Up to 20% of the simulated projected radial distributions show excess counts similar to the observations, which are however, because of background/foreground AGN and hence, not physically associated with the cluster. Our analysis emphasises the importance of projection effects and shows that current observations of $z\approx1$ clusters remain inconclusive on the activation of SMBHs during infall.

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arXiv2024

AGN feedback in the Local Universe: multiphase outflow of the Seyfert galaxy NGC 5506

We present new optical GTC/MEGARA seeing-limited (0.9") integral-field observations of NGC 5506, together with ALMA observations of the CO(3-2) transition at a 0.2" (25 pc) resolution. NGC 5506 is a luminous (bolometric luminosity of $\sim 10^{44}$ erg/s) nearby (26 Mpc) Seyfert galaxy, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS). We modelled the CO(3-2) kinematics with 3D-Barolo, revealing a rotating and outflowing cold gas ring within the central 1.2 kpc. We derived an integrated cold molecular gas mass outflow rate for the ring of 8 M$_{\odot}$/yr. We fitted the optical emission lines with a maximum of two Gaussian components to separate rotation from non-circular motions. We detected high [OIII]$λ$5007 projected velocities (up to 1000 km/s) at the active galactic nucleus (AGN) position, decreasing with radius to an average 330 km/s around 350 pc. We also modelled the [OIII] gas kinematics with a non-parametric method, estimating the ionisation parameter and electron density in every spaxel, from which we derived an ionised mass outflow rate of 0.076 M$_{\odot}$/yr within the central 1.2 kpc. Regions of high CO(3-2) velocity dispersion, extending to projected distances of 350 pc from the AGN, appear to be the result from the interaction of the AGN wind with molecular gas in the galaxy's disc. Additionally, we find the ionised outflow to spatially correlate with radio and soft X-ray emission in the central kiloparsec. We conclude that the effects of AGN feedback in NGC 5506 manifest as a large-scale ionised wind interacting with the molecular disc, resulting in outflows extending to radial distances of 610 pc

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arXiv2023

An extended Lyman $α$ outflow from a radio galaxy at z=3.7?

Spatially resolved observations of AGN host galaxies undergoing feedback processes are one of the most relevant avenues through which galactic evolution can be studied, given the long lasting effects AGN feedback has on gas reservoirs, star formation, and AGN environments at all scales. Within this context we report results from VLT/MUSE integral field optical spectroscopy of TN J1049-1258, one of the most powerful radio sources known, at a redshift of 3.7. We detected extended ($\sim$ 18 kpc) Lyman $α$ emission, spatially aligned with the radio axis, redshifted by 2250 $\pm$ 60 km s$^{-1}$ with respect to the host galaxy systemic velocity, and co-spatial with UV continuum emission. This Lyman $α$ emission could arise from a companion galaxy, although there are arguments against this interpretation. Alternatively, it might correspond to an outflow of ionized gas stemming from the radio galaxy. The outflow would be the highest redshift spatially resolved ionized outflow to date. The enormous amount of energy injected, however, appears to be unable to quench the host galaxy's prodigious star formation, occurring at a rate of $\sim$4500 M$_{\odot} yr^{-1}$, estimated using its far infra-red luminosity. Within the field we also found two companion galaxies at projected distances of $\sim$25 kpc and $\sim$60 kpc from the host, which suggests the host galaxy is harbored within a protocluster.

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arXiv2023

Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time

The origin of obscuration in Active Galactic Nuclei (AGN) is still an open debate. In particular, it is unclear what drives the relative contributions to the line-of-sight column densities from galaxy-scale and torus-linked obscuration. The latter source is expected to play a significant role in Unification Models, while the former is thought to be relevant in both Unification and Evolutionary Models. In this work, we make use of a combination of cosmological semi-analytic models and semi-empirical prescriptions for the properties of galaxies and AGN, to study AGN obscuration. We consider a detailed object-by-object modelling of AGN evolution, including different AGN light curves (LCs), gas density profiles, and also AGN feedback-induced gas cavities. Irrespective of our assumptions on specific AGN LC or galaxy gas fractions, we find that, on the strict assumption of an exponential profile for the gas component, galaxy-scale obscuration alone can hardly reproduce the fraction of $\log (N_{\rm H}/$cm$^{-2}) \geq 24$ sources at least at $z\lesssim3$. This requires an additional torus component with a thickness that decreases with luminosity to match the data. The torus should be present in all evolutionary stages of a visible AGN to be effective, although galaxy-scale gas obscuration may be sufficient to reproduce the obscured fraction with $22<\log (N_{\rm H}/$cm$^{-2})<24$ (Compton-thin, CTN) if we assume extremely compact gas disc components. The claimed drop of CTN fractions with increasing luminosity does not appear to be a consequence of AGN feedback, but rather of gas reservoirs becoming more compact with decreasing stellar mass.

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arXiv2023

Obscuration beyond the nucleus: infrared quasars can be buried in extreme compact starbursts

In the standard quasar model, the accretion disk obscuration is due to the canonical dusty torus. Here, we argue that a substantial part of the quasar obscuration can come from the interstellar medium (ISM) when the quasars are embedded in compact starbursts. We use an obscuration-unbiased sample of 578 infrared (IR) quasars at $z\approx 1-3$ and archival ALMA submillimeter host galaxy sizes to investigate the ISM contribution to the quasar obscuration. We calculate SFR and ISM column densities for the IR quasars and a control sample of submillimeter galaxies (SMGs) not hosting quasar activity and show that: (1) the quasar obscured fraction is constant up to $\rm SFR\approx 300 \: M_{\odot} \: yr^{-1}$, and then increases towards higher SFR, suggesting that the ISM obscuration plays a significant role in starburst host galaxies, and (2) at $\rm SFR\gtrsim 300 \: M_{\odot} \: yr^{-1}$, the SMGs and IR quasars have similarly compact submillimeter sizes ($R_{\rm e}\approx 0.5-3\rm \: kpc$) and, consequently, the ISM can heavily obscure the quasar, even reaching Compton-thick ($N_{\rm H}>10^{24} \rm \: cm^{-2}$) levels in extreme cases. Based on our results, we infer that $\approx 10-30\%$ of the IR quasars with $\rm SFR\gtrsim 300 \: M_{\odot} \: yr^{-1}$ are obscured solely by the ISM.

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arXiv2023

A new discovery space opened by eROSITA: Ionised AGN outflows from X-ray selected samples

In the context of an evolutionary model, the outflow phase of an Active Galactic Nuclei (AGN) occurs at the peak of its activity, once the central SMBH is massive enough to generate sufficient power to counterbalance the potential well of the host galaxy. This phase plays a vital role in galaxy evolution. We aim to apply various selection methods to isolate powerful AGNs in the feedback phase, trace and characterise their outflows, and explore the link between AGN luminosity and outflow properties. We applied a combination of methods to the eROSITA Final Equatorial Depth survey (eFEDS) catalogue and isolated ~1400 candidates at z>0.5 out of ~11750 AGNs (~12\%). We tested the robustness of our selection on the small subsample of 50 sources with available good quality SDSS spectra at 0.5 1\%. We find that the majority of the outflows have momentum flux ratios lower than 20 which rules out an energy-conserving nature. Our present work points to the unequivocal existence of a rather short AGN outflow phase, paving the way towards a new avenue to dissect AGN outflows in large samples within eROSITA and beyond.

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arXiv2023

Mapping the stellar population and gas excitation of MaNGA galaxies with MEGACUBES. Results for AGN versus control sample

We present spaxel-by-spaxel stellar population fits for the $\sim$10 thousand MaNGA datacubes. We provide multiple extension fits files, nominated as MEGACUBES, with maps of several properties as well as emission-line profiles that are provided for each spaxel. All the MEGACUBES are available through a web interface (\url{https://manga.linea.org.br/} or \url{http://www.if.ufrgs.br/~riffel/software/megacubes/}). We also defined a final Active Galactic Nuclei (AGN) sample, as well as a control sample matching the AGN host galaxy properties. We have analysed the stellar populations and spatially resolved emission-line diagnostic diagrams of these AGNs and compared them with the control galaxies sample. We find that the relative fractions of young ($t \leq $56 Myr) and intermediate-age (100 Myr $\leq t \leq$ 2 Gyr) show predominantly a positive gradient for both AGNs and controls. The relative fraction of intermediate-age stellar population is higher in AGN hosts when compared to the control sample, and this difference becomes larger for higher [O III] luminosity AGNs. We attribute this to the fact that extra gas is available in these more luminous sources and that it most likely originates from mass-loss from the intermediate-age stars. The spatially resolved diagnostic diagrams reveal that the AGN emission is concentrated in the inner 0.5 $R_e$ (effective radius) region of the galaxies, showing that the AGN classification is aperture dependent and that emission-line ratios have to be taken together with the H$α$ equivalent width for proper activity classification. We present a composite ``BPT+WHAN" diagram that produces a more comprehensive mapping of the gas excitation.

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arXiv2023

The role of grain size in AGN torus dust models

Fits the infrared spectra from the nuclear regions of AGN can place constraints on the dust properties, distribution, and geometry by comparison with models. However, none of the currently available models fully describe the observations of AGN currently available. Among the aspects least explored, here we focus on the role of dust grain size. We offer the community a new spectral energy distribution (SED) library, hereinafter [GoMar23] model, which is based on the two-phase torus model developed before with the inclusion of the grain size as a model parameter, parameterized by the maximum grain size Psize or equivalently the mass-weighted average grain size < P >. We created 691,200 SEDs using the SKIRT code, where the maximum grain size can vary within the range Psize = 0.01 - 10.0um ( < P >= 0.007 - 3.41um). We fit this new and several existing libraries to a sample of 68 nearby and luminous AGNs with Spitzer/IRS spectra dominated by AGN-heated dust. We find that the [GoMar23] model can adequately reproduce up to 85-88% of the spectra. The dust grain size parameter significantly improves the final fit in up to 90% of these spectra. Statistical tests indicate that the grain size is the third most important parameter in the fitting procedure (after the size and half opening angle of the torus). The requirement of a foreground extinction by our model is lower compared to purely clumpy models. We find that 41% of our sample requires that the maximum dust grain size is as large as Psize =10um (< P >= 3.41um). Nonetheless, we also remark that disk+wind and clumpy torus models are still required to reproduce the spectra of a non-negligible fraction of objects, suggesting the need for several dust geometries to explain the infrared continuum of AGN. This work provides tentative evidence for dust grain growth in the proximity of the AGN.

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arXiv2022

The demographics of obscured AGN from X-ray spectroscopy guided by multiwavelength information

A complete census of Active Galactic Nuclei (AGN) is a prerequisite for understanding the growth of supermassive black holes across cosmic time. A significant challenge toward this goal is the whereabouts of heavily obscured AGN that remain uncertain. This paper sets new constraints on the demographics of this population by developing a methodology that combines X-ray spectral information with priors derived from multiwavelength observations. We select X-ray AGN in the Chandra COSMOS Legacy survey and fit their $2.2-500μm$ spectral energy distributions with galaxy and AGN templates to determine the mid-infrared ($6μm$) luminosity of the AGN component. Empirical correlations between X-ray and $6μm$ luminosities are then adopted to infer the intrinsic accretion luminosity at X-rays for individual AGN. This is used as prior information in our Bayesian X-ray spectral analysis to estimate physical properties, such as line-of-sight obscuration. Our approach breaks the degeneracies between accretion luminosity and obscuration that affect X-ray spectral analysis, particularly for the most heavily obscured (Compton-Thick) AGN with low photon counts X-ray spectra. The X-ray spectral results are then combined with the selection function of the Chandra COSMOS Legacy survey to derive the AGN space density and a Compton-Thick fraction of $21.0^{+16.1}_{-9.9}\%$ at redshifts $z<0.5$. At higher redshift, our analysis suggests upper limits to the Compton-Thick AGN fraction of $\le 40\%$. These estimates are at the low end of the range of values determined in the literature and underline the importance of multiwavelength approaches for tackling the challenge of heavily obscured AGN demographics.

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arXiv2022

Spatially resolved evidence of the impact of quasar driven outflows on recent star formation : The case of Mrk 34

We present the results of our spatially resolved investigation into the interplay between the ages of the stellar populations and the kinematics of the warm ionised outflows in the well-studied type II quasar Markarian 34. Utilising IFS data, we determine the spatial distribution of the young stellar population (YSP; $t_{ysp} < 100 \mbox{ Myr}$) using spectral synthesis modelling. We also employ the $\mbox{[OIII]}λ5007$ emission line as a tracer of the warm ionised gas kinematics. We demonstrate a spatial correlation between the outer edges of the blue-side of the outflow and an enhancement in the proportion of the YSP flux, suggesting that the outflow is responsible for triggering star formation in this region. In regions with more highly disrupted gas kinematics, we find that the proportion of YSP flux is consistent with that found outside the outflow region, suggesting that the increased disruption is preventing a similar enhancement in star formation from occurring. Our analysis suggests that Mrk 34 is an example of quasar driven outflows simultaneously producing both `positive' and `preventive' feedback, further demonstrating the complex nature of the relationship between quasars and their host galaxies.

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