arXiv subjects

E. López-Rodríguez

Publications and source records attributed to E. López-Rodríguez.

10 recordsLinked to original sources

arXiv2026

The Galaxy Activity, Torus, and Outflow Survey (GATOS): N. Unveiling physical processes in local active galaxies. Unsupervised hierarchical clustering of JWST MIRI/MRS observations

With the rise of the integral field spectroscopy, we are currently dealing with large amounts of spatially resolved data, whose analysis has become challenging, especially when observing complex objects such as nearby galaxies. We aim to develop a method to automatically separate different physical regions within the central parts (1"~160 pc, on average) of galaxies. This can allow us to better understand the systems, and provide an initial characterisation of the main ionisation sources affecting its evolution. We have developed an unsupervised hierarchical clustering algorithm to analyse data cubes based on spectral similarity. It clusters together spaxels with similar spectra, which is useful to disentangle between different physical processes. We have applied this method to a sample of 15 nearby (distances <100 Mpc) galaxies, 7 from the Galaxy Activity, Torus, and Outflow Survey (GATOS) and 8 archival sources, all observed with the medium resolution spectrometer (MRS) of the Mid-Infrared Instrument (MIRI) on board of the JWST. From the clusters, we computed their median spectrum and measured the line and continuum properties. We used these measurements to train random forest models and create several empirical mid-IR diagnostic diagrams for the MRS channel 3 wavelength range, including among others the bright [Ne II], [Ne III], and [Ne V] lines, several H2 transitions, and PAH features. The clustering technique allows to differentiate emission coming from an AGN, the disc, and star forming regions in galaxies, and other composite regions, potentially ionised by several sources simultaneously. This is supported by the results from the empirical diagnostic diagrams, that are indeed able to separate physically distinct regions. This innovative method serves as a tool to identify regions of interest in any data cube prior to an in-depth analysis of the sources. [abridged]

astro-ph.GA↗

arXiv2024

Molecular gas stratification and disturbed kinematics in the Seyfert galaxy MCG-05-23-16 revealed by JWST and ALMA

Understanding the processes that drive the morphology and kinematics of molecular gas in galaxies is crucial for comprehending star formation and, ultimately, galaxy evolution. Using data obtained with the James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA), we study the behavior of the warm molecular gas at temperatures of hundreds of Kelvin and the cold molecular gas at tens of Kelvin in the galaxy MCG$-$05$-$23$-$16, which hosts an active galactic nucleus (AGN). Hubble Space Telescope (HST) images of this spheroidal galaxy, classified in the optical as S0, show a dust lane resembling a nuclear spiral and a surrounding ring. These features are also detected in CO(2$-$1) and H2, and their morphologies and kinematics are consistent with rotation plus local inward gas motions along the kinematic minor axis in the presence of a nuclear bar. The H2 transitions 0-0 S(3), 0-0 S(4), and 0-0 S(5), which trace warmer and more excited gas, show more disrupted kinematics than 0-0 S(1) and 0-0 S(2), including clumps of high-velocity dispersion (of up to $\sim$ 160 km/s), in regions devoid of CO(2$-$1). The kinematics of one of these clumps, located at $\sim$ 350 pc westward from the nucleus, are consistent with outflowing gas, possibly driven by localized star formation traced by Polycyclic Aromatic Hydrocarbon (PAH) emission at 11.3 $μ$m. Overall, we observe a stratification of the molecular gas, with the colder gas located in the nuclear spiral, ring, and connecting arms, while most warmer gas with higher velocity-dispersion fills the inter-arm space. The compact jet, approximately 200 pc in size, detected with Very Large Array (VLA) observations, does not appear to significantly affect the distribution and kinematics of the molecular gas, possibly due to its limited intersection with the molecular gas disc.

astro-ph.GA↗

arXiv2024

A biconical ionised gas outflow and evidence for positive feedback in NGC 7172 uncovered by MIRI/JWST

We present observations of the type-2 Seyfert NGC7172 obtained with the medium-resolution spectrometer (MRS) of the Mid-Infrared Instrument (MIRI) on board of the JWST. This galaxy hosts one of the lowest ionised gas mass outflow rates (Mout~0.005 M/yr) in a sample of six AGN with similar bolometric luminosities (log Lbol~44erg/s) within the Galactic Activity, Torus and Outflow Survey (GATOS). We aim to understand the properties of the ionised gas outflow, mainly using the emission lines from the neon transitions, that cover a broad range of ionisation potentials (IP) from ~20 eV to ~130 eV. We applied parametric and non-parametric methods to characterise the line emission and kinematics. The low excitation lines (IP<25eV, e.g.[NeII]) trace the rotating disc emission. The high excitation lines (IP>90eV, e.g.[NeV]), which are likely photoionised exclusively by the AGN, are expanding in the direction nearly perpendicular to the disc of the galaxy, with maximum projected velocities of ~350-500 km/s. In particular, [NeV] and [NeVI] lines reveal a biconical ionised gas outflow emerging N-S from the nuclear region, extending at least ~2.5"N and 3.8"S (projected distance of ~450 and 680 pc). Most of the emission arising in the northern part of the cone was not previously detected due to obscuration. Given the almost face-on orientation of the outflow and the almost edge-on orientation of the galaxy, NGC7172 may be a case of weak coupling. Nevertheless, we found evidence for positive feedback in two distinct outflowing clumps at projected distances of 3.1" and 4.3" (i.e. ~560 and 780 pc) SW from the AGN. We estimated a star formation rate in these regions using the [NeII] and [NeIII] luminosities of 0.08 M/yr, that is ~10% of that found in the circumnuclear ring. The star formation activity might have been triggered by the interaction between the ionised gas outflow and the ISM of the galaxy.

astro-ph.GA↗

arXiv2024

Deciphering the imprint of AGN feedback in Seyfert galaxies: Nuclear-scale molecular gas deficits

We use a sample of 64 nearby (D=7-45 Mpc) disk galaxies including 45 AGN and 19 non-AGN, that have high spatial resolution multiline CO observations obtained with the ALMA and/or PdBI arrays to study the distribution of cold molecular gas in their circumunuclear disks (CND). We analyze whether the concentration of cold molecular gas changes as a function of the X-ray luminosity in the 2-10 keV range ($L_{\rm X}$). We also study the concentration of the hot molecular gas using NIR data obtained for the H2 1-0S(1) line. We find a turnover in the distribution of the cold molecular gas concentration as a function of $L_{\rm X}$ with a breakpoint which divides the sample into two branches: the AGN build-up branch ($L_{\rm X}\leq10^{41.5\pm0.3}$erg/s) and the AGN feedback branch ($L_{\rm X}\geq10^{41.5\pm0.3}$erg/s) . Lower luminosity AGN and non-AGN of the AGN build-up branch show high cold molecular gas concentrations and centrally peaked radial profiles on nuclear ($r\leq50$~pc) scales. Higher luminosity AGN of the AGN feedback branch, show a sharp decrease in the concentration of molecular gas and flat or inverted radial profiles. The cold molecular gas concentration index ($CCI$), defined as the ratio of surface densities at $r\leq50$~pc and $r\leq200$~pc , namely $CCI \equiv$~log$_{\rm 10}(Σ^{\rm gas}_{\rm 50}/Σ^{\rm gas}_{\rm 200}$), spans a factor ~4-5 between the galaxies lying at the high end of the AGN build-up branch and the galaxies of the AGN feedback branch. The concentration and radial distributions of the hot molecular gas in our sample follow less extreme trends as a function of the X-ray luminosity. These observations confirm, on a three times larger sample, previous evidence found by the GATOS survey that the imprint of AGN feedback on the CND-scale distribution of molecular gas is more extreme in higher luminosity Seyfert galaxies of the local universe.

astro-ph.GA↗

arXiv2023

The Galaxy Activity, Torus, and Outflow Survey (GATOS). III: Revealing the inner icy structure in local AGN

We use JWST/MIRI MRS spectroscopy of a sample of six local obscured type 1.9/2 active galactic nuclei (AGN) to compare their nuclear mid-IR absorption bands with the level of nuclear obscuration traced by X-rays. This study is the first to use sub-arcsecond angular resolution data of local obscured AGN to investigate the nuclear mid-IR absorption bands with a wide wavelength coverage (4.9-28.1 $μ$m). All the nuclei show the 9.7 $μ$m silicate band in absorption. We compare the strength of the 9.7 and 18 $μ$m silicate features with torus model predictions. The observed silicate features are generally well explained by clumpy and smooth torus models. We report the detection of the 6 $μ$m dirty water ice band (i.e., a mix of water and other molecules such as CO and CO$_2$) at sub-arcsecond scales ($\sim$0.26 arcsec at 6 $μ$m; inner $\sim$50 pc) in a sample of local AGN with different levels of nuclear obscuration in the range log N$_{\rm H}^{\rm X-Ray}$(cm$^{-2}$)$\sim22-25$. We find a good correlation between the 6 $μ$m water ice optical depths and N$_{\rm H}^{\rm X-Ray}$. This result indicates that the water ice absorption might be a reliable tracer of the nuclear intrinsic obscuration in AGN. The weak water ice absorption in less obscured AGN (log N$_H^{X-ray}$ (cm$^{-2}$)$\lesssim$23.0 cm$^{-2}$) might be related to the hotter dust temperature ($>$T$_{sub}^{H_2O}\sim$110 K) expected to be reached in the outer layers of the torus due to their more inhomogeneous medium. Our results suggest it might be necessary to include the molecular content, such as, H$_2$O, aliphatic hydrocarbons (CH-) and more complex PAH molecules in torus models to better constrain key parameters such as the torus covering factor (i.e. nuclear obscuration).

astro-ph.GA↗

arXiv2022

Torus and polar dust dependence on AGN properties

We present a statistical analysis of the properties of the obscuring material around active galactic nuclei (AGN). This study represents the first of its kind for an ultra-hard X-ray (14-195keV; Swift/BAT) volume-limited (DL<40 Mpc) sample of 24 Seyfert (Sy) galaxies (BCS40 sample) using high angular resolution infrared data and various torus models: smooth, clumpy and two-phase torus models and clumpy disc+wind models. We find that the smooth, clumpy and two-phase torus models (i.e. without including the polar dusty wind component) and disc+wind models provide best fits for a comparable number of galaxies, 8/24 (33.3%) and 9/24 (37.5%), respectively. We find that the best-fitted models depend on the hydrogen column density (NH), which is related to the X-ray (unobscured/obscured) and/or optical (Sy1/Sy2) classification. In particular, smooth, clumpy and two-phase torus models best reproduce the infrared (IR) emission of AGN with relatively high hydrogen column density (median value of log (NH)=23.5+-0.8; i.e. Sy2). However, clumpy disc+wind models provide the best fits to the nuclear IR spectral energy distributions (SEDs) of Sy1/1.8/1.9 (median value of log (NH)=21.0+-1.0), specifically in the near-IR (NIR) range. The success of the disc+wind models in fitting the NIR emission of Sy1 galaxies is due to the combination of adding large graphite grains to the dust composition and self-obscuration effects caused by the wind at intermediate inclinations. In general, we find that the Seyfert galaxies having unfavourable (favourable) conditions, i.e. nuclear hydrogen column density and Eddington ratio, for launching IR dusty polar outflows are best-fitted with smooth, clumpy and two-phase torus (disk+wind) models confirming the predictions from simulations. Therefore, our results indicate that the nature of the inner dusty structure in AGN depend on the intrinsic AGN properties.

astro-ph.GA↗

arXiv2021

The Galaxy Activity, Torus and Outflow Survey (GATOS): II. Torus and polar dust emission in nearby Seyfert galaxies

We compare mid-IR and ALMA far-IR images of 12 nearby Seyferts selected from GATOS. The mid-IR unresolved emission contributes more than 60% of the nuclear emission in most galaxies. By contrast, the ALMA 870micron continuum emission is mostly resolved and typically along the torus equatorial direction (Paper I, Garcia-Burillo et al. 2021). The Eddington ratios and nuclear hydrogen column densities NH of half the sample are favorable to launching polar and/or equatorial dusty winds, according to simulations. Six show mid-IR extended emission in the polar direction as traced by the NLR and perpendicular to the ALMA emission. In a few, the nuclear NH might be too high to uplift large quantities of dusty material along the polar direction. Five galaxies have low NH and/or Eddington ratios and thus polar dusty winds are not likely. We generate new CAT3D-WIND disk-wind model images. At low wind-to-disk cloud ratios the far-IR model images have disk- and ring-like morphologies. The X-shape associated with dusty winds is seen better in the far-IR at intermediate-high inclinations for the extended-wind configurations. In most models, the mid-IR emission comes from the inner part of the disk/cone. Extended bi-conical and one-sided polar mid-IR emission is seen in extended-wind configurations and high wind-to-disk cloud ratios. When convolved to our resolution, the model images reproduce qualitative aspects of the observed morphologies. Low-intermediate wind-to-disk ratios are required to account for the large fractions of unresolved mid-IR emission. This work and Paper I provide observational support for the torus+wind scenario. The wind component is more relevant at high Eddington ratios and/or AGN luminosities, and polar dust emission is predicted at NH of up to $10^{24}$cm$^{-2}$. The torus/disk component, on the other hand, prevails at low luminosities and/or Eddington ratios. (Abridged)

astro-ph.GA↗

arXiv2021

The Galaxy Activity, Torus and Outflow Survey (GATOS) I. ALMA images of dusty molecular tori in Seyfert galaxies

We present the first results of the Galaxy Activity, Torus and Outflow Survey (GATOS), a project aimed at understanding the properties of the dusty molecular tori and their connection to the host galaxy in nearby Seyfert galaxies. Our project expands the range of AGN luminosities and Eddington ratios covered by previous surveys of Seyferts conducted by ALMA and allows us to study the gas feeding and feedback cycle in a combined sample of 19 Seyferts. We used ALMA to obtain new images of the emission of molecular gas and dust using the CO(3-2) and HCO+(4-3) lines as well as their underlying continuum emission at 870 microns with high spatial resolutions (0.1'' ~ 7 - 13 pc) in the CND of 10 nearby (D < 28 Mpc) Seyfert galaxies. Our new ALMA observations detect 870 micron continuum and CO line emission from spatially resolved disks located around the AGN in all the sources. The bulk of the continuum flux can be accounted for by thermal emission from dust in the majority of the targets. For most of the sources the disks show a preponderant orientation perpendicular to the AGN wind axes, as expected for dusty molecular tori. The median diameters and molecular gas masses of the tori are ~ 42 pc, and ~ 6 x 10**5 Msun, respectively. We find a positive correlation between the line-of-sight gas column densities responsible for the absorption of X-rays and the molecular gas column densities derived from CO towards the AGN in our sources. The radial distributions of molecular gas in the CND of our combined sample show signs of nuclear-scale molecular gas deficits. We also detect molecular outflows in the sources that show the most extreme nuclear-scale gas deficits in our sample. These observations find for the first time supporting evidence that the imprint of AGN feedback is more extreme in higher luminosity and/or higher Eddington ratio Seyfert galaxies.

astro-ph.GA↗

arXiv2018

Multiwavelength Photometric and Spectropolarimetric Analysis of the FSRQ 3C 279

In this paper, we present light curves for 3C 279 over a time period of six years; from 2008 to 2014. Our multiwavelength data comprise 1 mm to gamma-rays, with additional optical polarimetry. Based on the behaviour of the gamma-ray light curve with respect to other bands, we identified three different activity periods. One of the activity periods shows anomalous behaviour with no gamma-ray counterpart associated with optical and NIR flares. Another anomalous activity period shows a flare in gamma-rays, 1 mm and polarization degree, however, it does not have counterparts in the UV continuum, optical and NIR bands. We find a significant overall correlation of the UV continuum emission, the optical and NIR bands. This correlation suggests that the NIR to UV continuum is co-spatial. We also find a correlation between the UV continuum and the 1 mm data, which implies that the dominant process in producing the UV continuum is synchrotron emission. The gamma-ray spectral index shows statistically significant variability and an anti-correlation with the gamma-ray luminosity. We demonstrate that the dominant gamma-ray emission mechanism in 3C 279 changes over time. Alternatively, the location of the gamma-ray emission zone itself may change depending on the activity state of the central engine.

astro-ph.HE↗

arXiv2016

The nuclear and integrated far-infrared emission of nearby Seyfert galaxies

We present far-infrared (FIR) $70-500\,μ$m imaging observations obtained with Herschel/PACS and SPIRE of 33 nearby (median distance of 30 Mpc) Seyfert galaxies from the Revised Shapley-Ames (RSA) catalogue. We obtain the FIR nuclear ($r=1\,$kpc and $r=2\,$kpc) and integrated spectral energy distributions (SEDs). We estimate the unresolved nuclear emission at 70 $μ$m and we fit the nuclear and integrated FIR SEDs with a grey body model. We find that the integrated FIR emission of the RSA Seyferts in our sample is dominated by emission from the host galaxy, with dust properties similar to those of normal galaxies (non AGN). We use four criteria to select galaxies whose nuclear $70\,μ$m emission has a significant AGN contribution: (1) elevated 70/160 $μ$m flux ratios, (2)spatially resolved, high dust temperature gradient, (3) $70\,μ$m excess emission with respect to the fit of the FIR SEDs with a grey body, and (4) excess of nuclear SFR obtained from $70\,μ$m over SFR from mid-infrared indicators. 16 galaxies (48 per cent of the initial sample) satisfy at least one of these conditions, whereas 10 satisfy half or more. After careful examination of these, we select six bona fide candidates (18 per cent of the initial sample) and estimate that $\sim 40-70$ per cent of their nuclear ($r=1-2\,$kpc) $70\,μ$m emission is contributed by dust heated by the AGN.

astro-ph.GA↗