arXiv subjects

R. Maiolino

Publications and source records attributed to R. Maiolino.

At least 91 records · Page 5Linked to original sources

arXiv2021

The ALPINE-ALMA [CII] survey: Dust mass budget in the early Universe

The dust content of normal galaxies and the dust mass density (DMD) at high-z (z>4) are unconstrained given the source confusion and the sensitivity limitations of previous observations. The ALMA Large Program to INvestigate [CII] at Early Times (ALPINE), which targeted 118 UV-selected star-forming galaxies at 4.4<z<5.9, provides a new opportunity to tackle this issue for the first time with a statistically robust dataset. We have exploited the rest-frame far-infrared (FIR) fluxes of the 23 continuum individually detected galaxies and stacks of continuum images to measure the dust content of the 118 UV-selected ALPINE galaxies. We have focused on the dust scaling relations and, by comparing them with predictions from chemical evolution models, we have probed the evolutionary stage of UV-selected galaxies at high-z. By using the observed correlation between the UV-luminosity and the dust mass, we have estimated the DMD of UV-selected galaxies at z~5, weighting the galaxies by means of the UV-luminosity function (UVLF). The derived DMD has been compared with the value we have estimated from the 10 ALPINE far-IR continuum blindly detected galaxies at the redshift of the ALPINE targets. The comparison of the observed dust scaling relations with chemical evolution models suggests that ALPINE galaxies are not likely progenitors of disc galaxies, but of intermediate and low mass proto-spheroids, resulting in present-day bulges of spiral or elliptical galaxies. Interestingly, this conclusion is in line with the independent morphological analysis, that shows that the majority (~70\%) of the dust-continuum detected galaxies have a disturbed morphology. The DMD obtained at z~5 from UV-selected sources is ~30% of the value obtained from blind far-IR selected sources, showing that the UV-selection misses the most dust-rich, UV-obscured galaxies.

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arXiv2021

MAGNUM survey: Compact jets causing large turmoil in galaxies -- Enhanced line widths perpendicular to radio jets as tracers of jet-ISM interaction

Outflows accelerated by AGN are commonly observed in the form of coherent, mildly collimated high-velocity gas directed along the AGN ionisation cones and kinetically powerful (>$10^{44-45}$ erg/s) jets. Recent works found that outflows can also be accelerated by low-power (<$10^{44}$ erg/s) jets, and the most recent cosmological simulations indicate that these are the dominant source of feedback on sub-kpc scales. We study the relation between radio jets and the distribution and kinematics of the ionised gas in IC 5063, NGC 5643, NGC 1068, and NGC 1386 as part of our MAGNUM survey of nearby Seyfert galaxies. All these objects host a small-scale (<1 kpc) low-power (<$10^{44}$ erg/s) radio jet that has small inclinations (<45°) with respect to the galaxy disc. We employed seeing-limited optical integral field spectroscopic observations from MUSE at VLT to obtain flux, kinematic, and excitation maps of the extended ionised gas, that we compared with archival radio images and Chandra X-ray observations. We detect a strong (up to >800-1000 km/s), extended (>1 kpc) and shock-excited emission-line velocity spread perpendicular to the AGN ionisation cones and jets in all four targets. These broad and symmetric line profiles are not associated with a single coherent velocity of the gas, differently from the 'classical' asymmetric-line outflow observed along the ionisation cones and jets. We interpret the observed phenomenon as due to the action of the jets perturbing the gas in the galaxy disc. These intense and extended velocity spreads perpendicular to AGN jets and cones are indeed currently only observed in galaxies hosting a low-power jet whose inclination is sufficiently low with respect to the galaxy disc to impact on and strongly affect its material. In line with cosmological simulations, our results demonstrate that low-power jets are indeed capable of affecting the host galaxy.

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arXiv2020

Missing [CII] emission from early galaxies

ALMA observations have revealed that [CII] 158$μ$m line emission in high-z galaxies is ~2-3$\times$ more extended than the UV continuum emission. Here we explore whether surface brightness dimming (SBD) of the [CII] line is responsible for the reported [CII] deficit, and the large $L_{\rm [OIII]}/L_{\rm [CII]}$ luminosity ratio measured in early galaxies. We first analyse archival ALMA images of nine z>6 galaxies observed in both [CII] and [OIII]. After performing several uv-tapering experiments to optimize the identification of extended line emission, we detect [CII] emission in the whole sample, with an extent systematically larger than the [CII] emission. Next, we use interferometric simulations to study the effect of SBD on the line luminosity estimate. About 40% of the extended [CII] component might be missed at an angular resolution of 0.8$^{\prime\prime}$, implying that $L_{\rm [CII]}$ is underestimated by a factor $\approx2$ in data at low (<7) signal-to-noise ratio . By combining these results, we conclude that $L_{\rm [CII]}$ of z>6 galaxies lies, on average, slightly below the local $L_{\rm [CII]}-SFR$ relation ($Δ^{z=6-9}=-0.07\pm0.3$), but within the intrinsic dispersion of the relation. SBD correction also yields $L_{\rm [OIII]}/L_{\rm [CII]}<10$, i.e. more in line with current hydrodynamical simulations.

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arXiv2020

Physics of ULIRGs with MUSE and ALMA: The PUMA project I. Properties of the survey and first MUSE data results

Ultraluminous infrared galaxies (ULIRGs) are characterised by extreme starburst (SB) and AGN activity, and are therefore ideal laboratories for studying the outflow phenomena. We have recently started a project called Physics of ULIRGs with MUSE and ALMA (PUMA), which is a survey of 25 nearby (z < 0.165) ULIRGs observed with the integral field spectrograph MUSE and the interferometer ALMA. This sample includes systems with both AGN and SB nuclear activity in the pre- and post-coalescence phases of major mergers. The main goals of the project are to study the prevalence of multi-phase outflows as a function of the galaxy properties, to constrain the driving mechanisms of the outflows (e.g. distinguish between SB and AGN winds), and to identify feedback effects on the host galaxy. In this first paper, we present details on the sample selection, MUSE observations, and derive first data products. MUSE data were analysed to study the dynamical status of each of the 21 ULIRGs observed so far, taking the stellar kinematics and the morphological properties inferred from MUSE narrow-band images into account. We also located the ULIRG nuclei, using near-IR (HST) and mm (ALMA) data, and studied their optical spectra to infer the ionisation state through BPT diagnostics, and outflows in both ionised and neutral gas. We show that the morphological and stellar kinematic classifications are consistent: post-coalescence systems are more likely associated with ordered motions, while interacting (binary) systems are dominated by non-ordered and streaming motions. We also find broad and asymmetric [OIII] and NaID profiles in almost all nuclear spectra, with line widths in the range 300-2000 km/s, possibly associated with AGN- and SB-driven winds. This result reinforces previous findings that indicated that outflows are ubiquitous during the pre- and post-coalescence phases of major mergers.

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arXiv2020

The WISSH QSOs project IX. Cold gas content and environment of luminous QSOs at z~2.4-4.7

Sources at the brightest end of QSO luminosity function during the peak epoch of star formation and black hole accretion (z~2-4, i.e. Cosmic noon) are privileged sites to study the feeding & feedback cycle of massive galaxies. We perform the first systematic study of cold gas properties in the most luminous QSOs, by characterising their host-galaxies and environment. We analyse ALMA, NOEMA and JVLA observations of FIR continuum, CO and [CII] emission lines in eight QSOs ($L_{\rm Bol}>3\times10^{47}$ erg/s) from the WISSH sample at z~2.4-4.7. We report a 100% emission line detection rate and a 80% detection rate in continuum emission, and we find CO emission to be consistent with the steepest CO ladders observed so far. Sub-mm data reveal presence of (one or more) bright companion galaxies around 80% of WISSH QSOs, at projected distances of 6-130 kpc. We observe a variety of sizes for the molecular gas reservoirs (1.7-10 kpc), associated with rotating disks with disturbed kinematics. WISSH QSOs typically show lower CO luminosity and higher star formation efficiency than FIR matched, z~0-3 main-sequence galaxies, implying that, given the observed SFR ~170-1100 $M_\odot$/yr, molecular gas is converted into stars on <50 Myr. Most targets show extreme dynamical to black-hole mass ratios $M_{\rm dyn}/M_{\rm BH}\sim3-10$, two orders of magnitude smaller than local relations. The molecular gas fraction in WISSH hosts is lower by a factor of ~10-100 than in star forming galaxies with similar $M_*$. WISSH QSOs undergo an intense growth phase of both the central SMBH and host-galaxy. They pinpoint high-density sites where giant galaxies assemble and mergers play a major role in the build-up of the final host-galaxy mass. The observed low molecular gas fraction and short depletion timescale are likely due to AGN feedback, as traced by fast AGN-driven ionised outflows in all our targets.

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arXiv2020

The ALPINE-ALMA [CII] survey: Dust attenuation properties and obscured star formation at z~4.4-5.8

We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at a redshift of ~4.4-5.8. Our analyses are based on the far infrared continuum observations of 118 galaxies at rest-frame 158μm obtained with the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [CII] at Early times (ALPINE). We study the connection between the ultraviolet (UV) spectral slope ($β$), stellar mass (M_*), and infrared excess (IRX=L_IR/L_UV). Twenty-three galaxies are individually detected in the continuum at >3.5 sigma significance. We perform a stacking analysis using both detections and nondetections to study the average dust attenuation properties at z~4.4-5.8. The individual detections and stacks show that the IRX-$β$ relation at z~5 is consistent with a steeper dust attenuation curve than typically found at lower redshifts (z<4). The attenuation curve is similar to or even steeper than that of the extinction curve of the Small Magellanic Cloud (SMC). This systematic change of the IRX-$β$ relation as a function of redshift suggests an evolution of dust attenuation properties at z>4. Similarly, we find that our galaxies have lower IRX values, up to 1dex on average, at a fixed mass compared to previously studied IRX-M_* relations at z<4, albeit with significant scatter. This implies a lower obscured fraction of star formation than at lower redshifts. Our results suggest that dust properties of UV-selected star forming galaxies at z>4 are characterised by (i) a steeper attenuation curve than at z<4, and (ii) a rapidly decreasing dust obscured fraction of star formation as a function of redshift. Nevertheless, even among this UV-selected sample, massive galaxies (log M_*/$M_\odot$>10) at z~5-6 already exhibit an obscured fraction of star formation of ~45%, indicating a rapid build-up of dust during the epoch of reionization.

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arXiv2020

The ALMA view of the high-redshift relation between supermassive black holes and their host galaxies

This work aims at studying the $M_{BH}-M_{dyn}$ relation of a sample of $2 5-10$) and the gas kinematics is spatially resolved and dominated by ordered rotation. The estimated dynamical masses place $6$ out of $10$ quasars above the local relation yielding to a $M_{BH}/M_{dyn}$ ratios $\sim10\times$ higher than those estimated in low-$z$ galaxies. On the other hand, we found that $4$ quasars at $z\sim 4-6$ have dynamical-to-BH mass ratios consistent with what is observed in early-type galaxies in the local Universe.

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arXiv2020

MUSE view of Arp220: Kpc-scale multi-phase outflow and evidence for positive feedback

Arp220 is the nearest and prototypical ULIRG, and shows evidence of pc-scale molecular outflows in its nuclear regions and strongly perturbed ionised gas kinematics on kpc scales. It is therefore the ideal system for investigating outflows and feedback phenomena in details. We investigate the feedback effects on the Arp220 ISM, deriving a detailed picture of the atomic gas in terms of physical and kinematic properties, with a spatial resolution never obtained before (0.56", i.e. ~ 210 pc). We use optical IFS observations from VLT/MUSE-AO to obtain spatially resolved stellar and gas kinematics, for both ionised ([N II]6583) and neutral (Na ID5891,96) components; we also derive dust attenuation, electron density, ionisation conditions and hydrogen column density maps to characterise the ISM properties. Arp220 kinematics reveal the presence of a disturbed, kpc-scale disk in the innermost nuclear regions, and highly perturbed, multi-phase (neutral and ionised) gas along the minor-axis of the disk, which we interpret as a galactic-scale outflow emerging from the Arp220 eastern nucleus. This outflow involves velocities up to ~ 1000 km/s at galactocentric distances of ~ 5 kpc, and has a mass rate of ~ 50 Msun/yr, and kinetic and momentum power of ~ 1e43 erg/s and ~ 1e35 dyne, respectively. The inferred energetics do not allow us to distinguish the origin of the outflows, i.e. whether they are AGN-driven or starburst-driven. We also present evidence for enhanced star formation at the edges of - and within - the outflow, with a star formation rate SFR ~ 5 Msun/yr (i.e. ~ 2% of the total SFR). Our findings suggest the presence of powerful winds in Arp220: they might be capable of removing or heating large amounts of gas from the host ("negative feedback"), but could be also responsible for triggering star formation ("positive feedback").

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arXiv2020

MOONS Surveys of the Milky Way and its Satellites

The study of resolved stellar populations in the Milky Way and other Local Group galaxies can provide us with a fossil record of their chemo-dynamical and star-formation histories over timescales of many billions of years. In the galactic components and stellar systems of the Milky Way and its satellites, individual stars can be resolved. Therefore, they represent a unique laboratory in which to investigate the details of the processes behind the formation and evolution of the disc and dwarf/irregular galaxies. MOONS at the VLT represents a unique combination of an efficient infrared multi-object spectrograph and a large-aperture 8-m-class telescope which will sample the cool stellar populations of the dense central regions of the Milky Way and its satellites, delivering accurate radial velocities, metallicities, and other chemical abundances for several millions of stars over its lifetime (see Cirasuolo et al., this issue). MOONS will observe up to 1000 targets across a 25-arcminute field of view in the optical and near-infrared (0.6-1.8 micron) simultaneously. A high-resolution (R~19700) setting in the H band has been designed for the accurate determination of stellar abundances such as alpha, light, iron-peak and neutron-capture elements.

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arXiv2020

MOONRISE: The Main MOONS GTO Extragalactic Survey

The MOONS instrument possesses an exceptional combination of large multiplexing, high sensitivity, broad simultaneous spectral coverage (from optical to near-infrared bands), large patrol area and high fibre density. These properties provide the unprecedented potential of enabling, for the very first time, SDSS-like surveys around Cosmic Noon (z~1-2.5), when the star formation rate in the Universe peaked. The high-quality spectra delivered by MOONS will sample the same nebular and stellar diagnostics observed in extensive surveys of local galaxies, providing an accurate and consistent description of the evolution of various physical properties of galaxies, and hence a solid test of different scenarios of galaxy formation and transformation. Most importantly, by spectroscopically identifying hundreds of thousands of galaxies at high redshift, the MOONS surveys will be capable of determining the environments in which primeval galaxies lived and will reveal how such environments affected galaxy evolution. In this article, we specifically focus on the main Guaranteed Time Observation (GTO) MOONS extragalactic survey, MOONRISE, by providing an overview of its scientific goals and observing strategy.

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arXiv2020

The ALPINE-ALMA [CII] Survey: CGM pollution and gas mixing by tidal stripping in a merging system at z~4.57

We present ALMA observations of a merging system at z ~ 4.57, observed as a part of the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey. Combining ALMA [CII] 158 micron and far-infrared continuum data with multi-wavelength ancillary data we find that the system is composed of two massive (Mstar >~ 10^10 Msun) star-forming galaxies experiencing a major merger (stellar mass ratio r_mass ~ 0.9) at close spatial (~13 kpc; projected) and velocity (delta_v < 300 km/s) separations, and two additional faint narrow [CII]-emitting satellites. The overall system belongs to a larger-scale protocluster environment and is coincident to one of its overdensity peaks. ALMA reveals also the presence of [CII] emission arising from a circumgalactic gas structure, extending up to a diameter-scale of ~30 kpc. Our morpho-spectral decomposition analysis shows that about 50% of the total flux resides between the individual galaxy components, in a metal-enriched gaseous envelope characterized by a disturbed morphology and complex kinematics. Similarly to observations of shock-excited [CII] emitted from tidal tails in local groups, our results can be interpreted as a possible signature of interstellar gas stripped by strong gravitational interactions, with a possible contribution from material ejected by galactic outflows and emission triggered by star formation in small faint satellites. Our findings suggest that mergers could be an efficient mechanism of gas mixing in the circumgalactic medium around high-z galaxies, and thus play a key role in the galaxy baryon cycle at early epochs.

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arXiv2020

The ALPINE-ALMA [CII] Survey: Obscured Star Formation Rate Density and Main Sequence of star-forming galaxies at z>4

Star formation rate (SFR) measurements at z>4 have relied mostly on rest-frame far-ultraviolet (FUV) observations. The corrections for dust attenuation based on IRX-$β$ relation are highly uncertain and are still debated in the literature. Hence, rest-frame far-infrared (FIR) observations are necessary to constrain the dust-obscured component of the SFR. In this paper, we exploit the rest-frame FIR continuum observations collected by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) to directly constrain the obscured SFR in galaxies at 4.4<z<5.9. We use stacks of continuum images to measure average infrared (IR) luminosities taking into account both detected and undetected sources. Based on these measurements, we measure the position of the main sequence of star-forming galaxies and the specific SFR (sSFR) at $z\sim4.5$ and $z\sim5.5$. We find that the main sequence and sSFR do not evolve significantly between $z\sim4.5$ and $z\sim5.5$, as opposed to lower redshifts. We develop a method to derive the obscured SFR density (SFRD) using the stellar masses or FUV-magnitudes as a proxy of FIR fluxes measured on the stacks and combining them with the galaxy stellar mass functions and FUV luminosity functions from the literature. We obtain consistent results independent of the chosen proxy. We find that the obscured fraction of SFRD is decreasing with increasing redshift but even at $z\sim5.5$ it constitutes around 61\% of the total SFRD.

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arXiv2020

Chemical abundances of Seyfert 2 AGNs-III. Reducing the oxygen abundance discrepancy

We investigate the discrepancy between oxygen abundance estimations for narrow-line regions (NLRs) of Active Galactic Nuclei (AGNs) type Seyfert 2 derived by using direct estimations of the electron temperature (Te-method) and those derived by using photoionization models. In view of this, observational emission-line ratios in the optical range (3000 < λ(Å) < 7000) of Seyfert 2 nuclei compiled from the literature were reproduced by detailed photoionization models built with the Cloudy code. We find that the derived discrepancies are mainly due to the inappropriate use of the relations between temperatures of the low (t2) and high (t3) ionization gas zones derived for H II regions in AGN chemical abundance studies. Using a photoionization model grid, we derived a new expression for t2 as a function of t3 valid for Seyfert 2 nuclei. The use of this new expression in the AGN estimation of the O/H abundances based on Te-method produces O/H abundances slightly lower (about 0.2 dex) than those derived from detailed photoionization models. We also find that the new formalism for the Te-method reduces by about 0.4 dex the O/H discrepancies between the abundances obtained from strong emission-line calibrations and those derived from direct estimations.

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arXiv2020

The ALPINE-ALMA [CII] survey. Little to no evolution in the [CII]-SFR relation over the last 13 Gyr

The [CII] 158 micron line is one of the strongest IR emission lines, which has been shown to trace the star-formation rate (SFR) of galaxies in the nearby Universe and up to $z \sim 2$. Whether this is also the case at higher redshift and in the early Universe remains debated. The ALPINE survey, which targeted 118 star-forming galaxies at $4.4 < z< 5.9$, provides a new opportunity to examine this question with the first statistical dataset. Using the ALPINE data and earlier measurements from the literature we examine the relation between the [CII] luminosity and the SFR over the entire redshift range from $z \sim 4-8$. ALPINE galaxies, which are both detected in [CII] and dust continuum, show a good agreement with the local L([CII])-SFR relation. Galaxies undetected in the continuum with ALMA are found to be over-luminous in [CII], when the UV SFR is used. After accounting for dust-obscured star formation, by an amount SFR(IR)$\approx$SFR(UV) on average, which results from two different stacking methods and SED fitting, the ALPINE galaxies show an L([CII])-SFR relation comparable to the local one. When [CII] non-detections are taken into account, the slope may be marginally steeper at high-z, although this is still somewhat uncertain. When compared in a homogeneous manner, the $z>6 $ [CII] measurements (detections and upper limits) do not behave very differently from the $z \sim 4-6$ data. We find a weak dependence of L([CII])/SFR on the Lyman-alpha equivalent width. Finally, we find that the ratio L([CII])/LIR $\sim (1-3) \times 10^{-3}$ for the ALPINE sources, comparable to that of "normal" galaxies at lower redshift. Our analysis, which includes the largest sample ($\sim 150$ galaxies) of [CII] measurements at $z>4$ available so far, suggests no or little evolution of the L([CII])-SFR relation over the last 13 Gyr of cosmic time.

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arXiv2020

The ALPINE-ALMA [CII] Survey: Size of Individual Star-Forming Galaxies at z=4-6 and their Extended Halo Structure

We present the physical extent of [CII] 158um line-emitting gas from 46 star-forming galaxies at z=4-6 from the ALMA Large Program to INvestigate CII at Early Times (ALPINE). Using exponential profile fits, we measure the effective radius of the [CII] line (r_e,[CII]) for individual galaxies and compare them with the rest-frame ultra-violet (UV) continuum (r_e,UV) from Hubble Space Telescope images. The effective radius r_e,[CII] exceeds r_e,UV by factors of ~2-3 and the ratio of r_e,[CII]/r_e,UV increases as a function of M_star. We do not find strong evidence that [CII] line, the rest-frame UV, and FIR continuum are always displaced over ~ 1-kpc scale from each other. We identify 30% of isolated ALPINE sources as having an extended [CII] component over 10-kpc scales detected at 4.1$σ$-10.9$σ$ beyond the size of rest-frame UV and far-infrared (FIR) continuum. One object has tentative rotating features up to ~10-kpc, where the 3D model fit shows the rotating [CII]-gas disk spread over 4 times larger than the rest-frame UV-emitting region. Galaxies with the extended [CII] line structure have high star-formation rate (SFR), stellar mass (M_star), low Lya equivalent-width, and more blue-shifted (red-shifted) rest-frame UV metal absorption (Lya line), as compared to galaxies without such extended [CII] structures. Although we cannot rule out the possibility that a selection bias towards luminous objects may be responsible for such trends, the star-formation driven outflow also explains all these trends. Deeper observations are essential to test whether the extended [CII] line structures are ubiquitous to high-z star-forming galaxies.

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arXiv2020

AION: An Atom Interferometer Observatory and Network

We outline the experimental concept and key scientific capabilities of AION (Atom Interferometer Observatory and Network), a proposed UK-based experimental programme using cold strontium atoms to search for ultra-light dark matter, to explore gravitational waves in the mid-frequency range between the peak sensitivities of the LISA and LIGO/Virgo/ KAGRA/INDIGO/Einstein Telescope/Cosmic Explorer experiments, and to probe other frontiers in fundamental physics. AION would complement other planned searches for dark matter, as well as probe mergers involving intermediate mass black holes and explore early universe cosmology. AION would share many technical features with the MAGIS experimental programme in the US, and synergies would flow from operating AION in a network with this experiment, as well as with other atom interferometer experiments such as MIGA, ZAIGA and ELGAR. Operating AION in a network with other gravitational wave detectors such as LIGO, Virgo and LISA would also offer many synergies.

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arXiv2020

SDSS IV MaNGA -- Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models

We measured gas-phase metallicity, ionisation parameter and dust extinction for 1795 representative local star-forming galaxies using integral field spectroscopy from the SDSS-IV MaNGA survey. We self-consistently derive these quantities by comparing observed line fluxes with photoionisation models using a Bayesian framework. We also present the first comprehensive study of the [SIII]$λλ$9069,9532 nebular lines, which have long been predicted to be ideal tracers of the ionisation parameter. Unfortunately, we find that current photoionisation models substantially over-predict [SIII] lines intensity, while broadly reproducing other observed optical line ratios. We discuss how to nonetheless make use of the information provided by [SIII] lines by setting a prior on the ionisation parameter. Following this approach, we derive spatially-resolved maps and radial profiles of metallicity and ionisation parameter. The metallicity radial profiles are comparable with previous works, with metallicity declining toward the outer parts and a flattening in the central regions, in agreement with infall models of galaxy formation, that predict that spiral discs build up through accretion of material, which leads to an inside-out growth. On the other hand, ionisation parameter radial profiles are flat for low-mass galaxies, while their slope becomes positive as galaxy mass increases. However, the ionisation parameter maps we obtain are clumpy, especially for low-mass galaxies. Ionisation parameter is tightly correlated with the H$α$ equivalent width [EW(H$α$)], following a nearly universal relation, which we attribute to the change of the spectral shape of ionising sources due to ageing of HII regions. We derive a positive correlation between ionisation parameter and metallicity at fixed EW(H$α$), in disagreement with previous theoretical works expecting an anti-correlation.

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arXiv2020

Universal bolometric corrections for AGN over 7 luminosity decades

The AGN bolometric correction is a key element to understand BH demographics and compute accurate BH accretion histories from AGN luminosities. However, current estimates still differ from each other by up to a factor of two to three, and rely on extrapolations at the lowest and highest luminosities. Here we revisit this fundamental issue presenting general hard X-ray ($K_{X}$) and optical ($K_{O}$) bolometric corrections, computed combining several AGN samples spanning the widest (about 7 dex) luminosity range ever used for this kind of studies. We analysed a total of $\sim 1000$ type 1 and type 2 AGN for which a dedicated SED-fitting has been carried out. We provide a bolometric correction separately for type 1 and type 2 AGN; the two bolometric corrections results to be in agreement in the overlapping luminosity range and therefore, for the first time, a universal bolometric correction for the whole AGN sample (both type 1 and type 2) has been computed. We found that $K_{X}$ is fairly constant at $log(L_{BOL}/L_{\odot}) < 11$, while it increases up to about one order of magnitude at $log(L_{BOL}/L_{\odot}) \sim 14.5$. A similar increasing trend has been observed when its dependence on either the Eddington ratio or the BH mass is considered, while no dependence on redshift up to $z\sim3.5$ has been found. On the contrary, the optical bolometric correction appears to be fairly constant (i.e. $K_{O} \sim 5$) whatever is the independent variable. We also verified that our bolometric corrections correctly predict the AGN bolometric luminosity functions. According to this analysis, our bolometric corrections can be applied to the whole AGN population in a wide range of luminosity and redshift.

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