arXiv subjects

A. Rodriguez-Ardila

Publications and source records attributed to A. Rodriguez-Ardila.

At least 19 recordsLinked to original sources

arXiv2023

The AGNIFS survey: spatially resolved observations of hot molecular and ionised outflows in nearby active galaxies

We present the hot molecular and warm ionised gas kinematics for 33 nearby ($0.001\lesssim z\lesssim0.056$) X-ray selected active galaxies using the H$_2 2.1218 μ$m and Br$γ$ emission lines observed in the K-band with the Gemini Near-Infrared Field Spectrograph (NIFS). The observations cover the inner 0.04$-$2 kpc of each AGN at spatial resolutions of 4$-$250 pc with a velocity resolution of $σ_{\rm inst}\approx$20 ${\rm km s^{-1}}$. We find that 31 objects (94 per cent) present a kinematically disturbed region (KDR) seen in ionised gas, while such regions are observed in hot molecular gas for 25 galaxies (76 per cent). We interpret the KDR as being due to outflows with masses of 10$^2-$10$^7$ M$_\odot$ and 10$^0-$10$^4$ M$_\odot$ for the ionised and hot molecular gas, respectively. The ranges of mass-outflow rates ($\dot{M}_{\rm out}$) and kinetic power ($\dot{E}_{\rm K}$) of the outflows are 10$^{-3}-$10$^{1}$ M$_\odot$yr$^{-1}$ and $\sim$10$^{37}$$-$10$^{43}$ erg s$^{-1}$ for the ionised gas outflows, and 10$^{-5}$$-$10$^{-2}$ M$_\odot$ yr$^{-1}$ and 10$^{35}$$-$10$^{39}$ erg s$^{-1}$ for the hot molecular gas outflows. The median coupling efficiency in our sample is $\dot{E}_{K}/L_{\rm bol}\approx1.8\times10^{-3}$ and the estimated momentum fluxes of the outflows suggest they are produced by radiation-pressure in low-density environment, with possible contribution from shocks.

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arXiv2021

A Gemini-NIFS view of the merger remnant NGC 34

The merger remnant NGC 34 is a local luminous infrared galaxy (LIRG) hosting a nuclear starburst and a hard X-ray source associated with a putative, obscured Seyfert~2 nucleus. In this work, we use adaptive optics assisted near infrared (NIR) integral field unit observations of this galaxy to map the distribution and kinematics of the ionized and molecular gas in its inner $\mathrm{1.2\,kpc \times 1.2\,kpc}$, with a spatial resolution of 70~pc. The molecular and ionized gas kinematics is consistent with a disc with projected major axis along a mean PA~=~$\mathrm{-9^{\circ}.2 \pm 0^{\circ}.9}$. Our main findings are that NGC~34 hosts an AGN and that the nuclear starburst is distributed in a circumnuclear star-formation ring with inner and outer radii of $\approx$~60 and 180~pc, respectively, as revealed by maps of the $\mathrm{[Fe II] / Paβ}$ and $\mathrm{H_{2} / Brγ}$ emission-line ratios, and corroborated by PCA Tomography analysis. The spatially resolved NIR diagnostic diagram of NGC~34 also identifies a circumnuclear structure dominated by processes related to the stellar radiation field and a nuclear region where $[Fe II]$ and H$_2$ emissions are enhanced relative to the hydrogen recombination lines. We estimate that the nuclear X-ray source can account for the central H$_2$ enhancement and conclude that $[Fe II]$ and H$_2$ emissions are due to a combination of photo-ionization by young stars, excitation by X-rays produced by the AGN and shocks. These emission lines show nuclear, broad, blue-shifted components that can be interpreted as nuclear outflows driven by the AGN.

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arXiv2021

The AGNIFS survey: distribution and excitation of the hot molecular and ionised gas in the inner kpc of nearby AGN hosts

We use the Gemini NIFS instrument to map the H$_2 2.1218μ$m and Br$γ$ flux distributions in the inner 0.04-2 kpc of a sample of 36 nearby active galaxies ($0.001\lesssim z\lesssim0.056$) at spatial resolutions from 4 to 250 pc. We find extended emission in 34 galaxies. In $\sim$55% of them, the emission in both lines is most extended along the galaxy major axis, while in the other 45% the extent follows a distinct orientation. The emission of H$_2$ is less concentrated than that of Br$γ$, presenting a radius that contains half of the flux 60% greater, on average. The H$_2$ emission is driven by thermal processes - X-ray heating and shocks - at most locations for all galaxies, where $0.4 6$ (seen in 40% of the galaxies), shocks are the main H$_2$ excitation mechanism, while in regions with H$_2$/Br$γ<0.4$ (25% of the sample) the H$_2$ emission is produced by fluorescence. The only difference we found between type 1 and type 2 AGN was in the nuclear emission-line equivalent widths, that are smaller in type 1 than in type 2 due to a larger contribution to the continuum from the hot dusty torus in the former. The gas masses in the inner 125 pc radius are in the range $10^1-10^4$ M$_\odot$ for the hot H$_2$ and $10^3-10^6$ M$_\odot$ for the ionised gas and would be enough to power the AGN in our sample for $10^5-10^8$ yr at their current accretion rates.

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arXiv2017

Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects

The increasing number of synoptic surveys made by small robotic telescopes, such as the photometric Catalina Real-Time Transient Survey (CRTS), represents a unique opportunity for the discovery of variable sources and improves the statistical samples of such classes of objects. Our goal is the discovery of magnetic Cataclysmic Variables (mCVs). These are rare objects, which probe interesting accretion scenarios controlled by the white dwarf magnetic field. In particular, improved statistics of mCVs would help to address open questions on their formation and evolution. We performed an optical spectroscopy survey to search for signatures of magnetic accretion in 45 variable objects selected mostly from the CRTS. In this sample we found 32 CVs, 22 being mCV candidates from which 13 are previously unreported as such. If the proposed classifications are confirmed, it would represent an increase of 4% in the number of known polars and 12% in the number of known IPs. A fraction of our initial sample was classified as extragalactic sources or other types of variable stars by the inspection of the identification spectra. Despite the inherent complexity in identifying a source as a mCV, variability-based selection followed by spectroscopic snapshot observations has proved to be an efficient strategy for their discoveries, being a relatively inexpensive approach in terms of telescope time.

astro-ph.SR↗

arXiv2016

The complex, dusty narrow-line region of NGC 4388: Gas-jet interactions, outflows, and extinction revealed by near-IR spectroscopy

We present Gemini/GNIRS spectroscopy of the Seyfert 2 galaxy NGC 4388, with simultaneous coverage from 0.85 - 2.5 $μ$m. Several spatially-extended emission lines are detected for the first time, both in the obscured and unobscured portion of the optical narrow line region (NLR), allowing us to assess the combined effects of the central continuum source, outflowing gas and shocks generated by the radio jet on the central 280 pc gas. The HI and [FeII] lines allow us to map the extinction affecting the NLR. We found that the nuclear region is heavily obscured, with E(B-V) ~1.9 mag. To the NE of the nucleus and up to ~150 pc, the extinction remains large, ~1 mag or larger, consistent with the system of dust lanes seen in optical imaging. We derived position-velocity diagrams for the most prominent lines as well as for the stellar component. Only the molecular gas and the stellar component display a well-organized pattern consistent with disk rotation. Other emission lines are kinematically perturbed or show little evidence of rotation. Extended high-ionization emission of sulfur, silicon and calcium is observed to distances of at least 200 pc both NE and SW of the nucleus. We compared flux ratios between these lines with photoionization models and conclude that radiation from the central source alone cannot explain the observed high-ionization spectrum. Shocks between the radio-jet and the ambient gas are very likely an additional source of excitation. We conclude that NGC 4388 is a prime laboratory to study the interplay between all these mechanisms.

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arXiv2016

The FeII emission in active galactic nuclei: excitation mechanisms and location of the emitting region

We present a study of FeII emission in the near-infrared region (NIR) for 25 active galactic nuclei (AGNs) to obtain information about the excitation mechanisms that power it and the location where it is formed. We employ a NIR FeII template derived in the literature and found that it successfully reproduces the observed FeII spectrum. The FeII bump at 9200 Angstroms detected in all objects studied confirms that Lyman-alpha fluorescence is always present in AGNs. The The correlation found between the flux of the 9200 Angstroms bump, the 1 micron lines and the optical FeII imply that Lyman-alpha fluorescence plays an important role in the FeII production. We determined that at least 18% of the optical FeII is due to this process while collisional excitation dominates the production of the observed FeII. The line profiles of FeII 10502, OI 11287, CaII 8664 and Paschen-beta were compared to gather information about the most likely location where they are emitted. We found that FeII, OI and CaII have similar widths and are, on average, 30% narrower than Paschen-beta. Assuming that the clouds emitting the lines are virialized, we show that the FeII is emitted in a region twice as far from the central source than Paschen-beta. The distance though strongly varies: from 8.5 light-days for NGC4051 to 198.2 light-days for Mrk509. Our results reinforce the importance of the FeII in the NIR to constrain critical parameters that drive its physics and the underlying AGN kinematics as well as more accurate models aimed at reproducing this complex emission.

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arXiv2015

The Nuclear Near-Infrared Spectral Properties of Nearby Galaxies

We present spectra of the nuclear regions of 50 nearby (D = 1 - 92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength range of approximately 0.85-2.5 microns at R~1300--1800. There is evidence that most of the galaxies host an active galactic nucleus (AGN), but the range of AGN luminosities (log (L2-10 keV [erg/s]) = 37.0-43.2) in the sample means that the spectra display a wide variety of features. Some nuclei, especially the Seyferts, exhibit a rich emission-line spectrum. Other objects, in particular the type 2 Low Ionisation Nuclear Emission Region galaxies, show just a few, weak emission lines, allowing a detailed view of the underlying stellar population. These spectra display numerous absorption features sensitive to the stellar initial mass function, as well as molecular bands arising in cool stars, and many other atomic absorption lines. We compare the spectra of subsets of galaxies known to be characterised by intermediate-age and old stellar populations, and find clear differences in their absorption lines and continuum shapes. We also examine the effect of atmospheric water vapor on the signal-to-noise ratio achieved in regions between the conventional NIR atmospheric windows, of potential interest to those planning observations of redshifted emission lines or other features affected by telluric H2O. Further exploitation of this data set is in progress, and the reduced spectra and data reduction tools are made available to the community.

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arXiv2013

Molecular Hydrogen and [Fe II] in Active Galactic Nuclei III: LINERS and Star Forming Galaxies

We study the kinematics and excitation mechanisms of H2 and [Fe II] lines in a sample of 67 emission-line galaxies with Infrared Telescope Facility SpeX near-infrared (NIR, 0.8-2.4 micrometers) spectroscopy together with new photoionisation models. H2 emission lines are systematically narrower than narrow-line region (NLR) lines, suggesting that the two are, very likely, kinematically disconnected. The new models and emission-line ratios show that the thermal excitation plays an important role not only in active galactic nuclei but also in star forming galaxies. The importance of the thermal excitation in star forming galaxies may be associated with the presence of supernova remnants close to the region emitting H2 lines. This hypothesis is further supported by the similarity between the vibrational and rotational temperatures of H2. We confirm that the diagram involving the line ratios H2 2.121/Br_gamma and [Fe II] 1.257/Pa_beta is an efficient tool for separating emission-line objects according to their dominant type of activity. We suggest new limits to the line ratios in order to discriminate between the different types of nuclear activity.

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arXiv2012

A Near-Infrared Template Derived from I Zw 1 for the FeII Emission in Active Galaxies

In AGN spectra, a series of FeII multiplets form a pseudo-continuum that extends from the ultraviolet to the near-infrared (NIR). This emission is believed to originate in the Broad Line Region (BLR), and it has been known for a long time that pure photoionization fails to reproduce it in the most extreme cases, as does the collisional-excitation alone. The most recent models by Sigut & Pradhan (2003) include details of the FeII ion microphysics and cover a wide range in ionization parameter log U_ion= (-3.0 -> -1.3) and density log n_H = (9.6 -> 12.6). With the aid of such models and a spectral synthesis approach, we study for the first time in detail the NIR emission of I Zw 1. The main goals are to confirm the role played by Lyα-fluorescence mechanisms in the production of the FeII spectrum and to construct the first semi-empirical NIR FeII template that best represents this emission and can be used to subtract it in other sources. A good overall match between the observed FeII+MgII features with those predicted by the best fitted model is obtained, corroborating the Lyα-fluorescence as a key process to understand the FeII spectrum. The best model is then adjusted by applying a deconvolution method on the observed FeII+MgII spectrum. The derived semi-empirical template is then fitted to the spectrum of Ark 564, suitably reproducing its observed FeII+MgII emission. Our approach extends the current set of available FeII templates into the NIR region.

astro-ph.CO↗

arXiv2011

The Compton-Thick Seyfert 2 Nucleus of NGC3281: Torus Constraints from the 9.7$μ$m Silicate Absorption

We present mid infrared (Mid-IR) spectra of the Compton-thick Seyfert 2 galaxy NGC\,3281, obtained with the Thermal-Region Camera Spectrograph (T-ReCS) at the Gemini South telescope. The spectra present a very deep silicate absorption at 9.7\,$μ$m, and [S{\sc\,iv]}\,10.5\,$μ$m and [Ne{\sc\,ii]}\,12.7\,$μ$m ionic lines, but no evidence of PAH emission. We find that the nuclear optical extinction is in the range 24 $\leq$ A$_{V}$ $\leq$ 83\,mag. A temperature T = 300\,K was found for the black-body dust continuum component of the unresolved 65\,pc nucleus and at 130\,pc SE, while the region at 130\,pc reveals a colder temperature (200\,K). We describe the nuclear spectrum of NGC\,3281 using a clumpy torus model that suggests that the nucleus of this galaxy hosts a dusty toroidal structure. According to this model, the ratio between the inner and outer radius of the torus in NGC\,3281 is $R_0/R_d$ = 20, with {\bf 14} clouds in the equatorial radius with optical depth of $τ_{V}$ = 40\,mag. We would be looking in the direction of the torus equatorial radius ($i$ = {\bf 60$^{\circ}$}), which has outer radius of R$_{0}\,\sim$ 11\,pc. The column density is N$_{H}\approx$\,{\bf 1.2}\,$\times\,10^{24}\,cm^{-2}$ and iron K$α$ equivalent width ($\approx$ 0.5 - 1.2\,keV) are used to check the torus geometry. Our findings indicate that the X-ray absorbing column density, which classifies NGC\,3281 as a Compton-thick source, may also be responsible for the absorption at 9.7\,$μ$m providing strong evidence that the silicate dust responsible for this absorption can be located in the AGN torus.

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arXiv2010

Near-infrared integrated spectra of Galactic globular clusters: testing simple stellar population models

We present SOAR/OSIRIS cross-dispersed NIR integrated spectra of 12 Galactic globular clusters that are employed to test Maraston (2005, M05) NIR EPS models, and to provide spectral observational constraints to calibrate future models. We measured Ew of the most prominent NIR absorption features. Optical Ew were also measured. The globular clusters Ew were compared with model predictions with ages within 4-15 Gyr, and metallicities between 1/200 and 2 Zsun. Observed integrated colours were also compared with models. The NIR integrated spectra among our sample appear qualitatively similar in most the absorption features. The M05 models can properly predict the optical Ew observed in globular clusters. Regarding the NIR, they do underestimate the strength of Mg I 1.49mum, but they can reproduce the observed Ew of Fe I 1.58mum, Si I 1.59mum, and CO 2.29mum, in about half of our sample. The remaining objects require the inclusion of intermediate-age populations. Thus, we suggest that the presence of C- and O-rich stars in models is important to reproduce the observed strengths of metallic lines. Another possibility is the lack of alpha-enhancement in the models. In the case of the optical and NIR Fe I lines, standard models and those that include blue horizontal branch stars, produce similar results. A similar trend is observed for Na I 5895A, while in the case of the G-band, the models with blue horizontal branch do describe better the observations. For most of the sample the optical to NIR colours are well described by the M05 models. In general, M05 models can provide reliable information on the NIR stellar population of galaxies, but only when Ew and colours are taken together, in other words, Ew and continuum fluxes should be simultaneously fitted. However, the results should be taken with caution, since the models tend to predict results biased towards young ages.

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arXiv2009

Probing the stellar population of seyfert galaxies: a near infrared perspective

We employ IRTF SpeX NIR (0.8--2.4mu m) spectra to investigate the stellar population (SP), active galactic nuclei (AGN), featureless continuum (FC) and hot dust properties in 9 Sy1 and 15 Sy2 galaxies. Both the {\sc starlight} code and the hot dust as an additional base element were used for the first time in this spectral range. Our synthesis shows significant differences between Sy1 and Sy2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy1 galaxies, and only of ~25% of the Sy2; about 50% of the Sy2 galaxies require an FC component contribution >20%; this fraction increases to about 60% in the Sy1. In about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Our SP synthesis confirms that the 1.1microns CN band can be used as a tracer of intermediate-age stellar populations.

astro-ph.CO↗

arXiv2009

Probing the near infrared stellar population of Seyfert galaxies

We employ IRTF SpeX NIR (0.8-2.4 microns) spectra to investigate the stellar population (SP), active galactic nuclei (AGN) featureless continuum (FC) and hot dust properties in 9 Sy 1 and 15 Sy 2 galaxies. Both the starlight code and the hot dust as an additional base element were used for the first time in this spectral range. We found evidence of correlation among the equivalent widths (W) Si I 1.59 microns x Mg I 1.58 microns, equally for both kinds of activity. Part of the W{Na I 2.21 microns} and W {CO 2.3 microns} strengths may be related to galaxy inclination. Our synthesis shows significant differences between Sy 1 and Sy 2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2; about 50 % of the Sy 2 galaxies require a $FC$ component contribution >20%, while this fraction increases to 60% in the Sy 1; also, in about 50 % of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Our SP synthesis confirms that the 1.1 micron CN band can be used as a tracer of intermediate-age SPs. The simultaneous fitting of SP, FC and hot dust components increased in ~150% the number of AGNs with hot dust detected and the mass estimated. The NIR emerges as an excellent window to study the stellar population of Sy 1 galaxies, as opposed to the usually heavily attenuated optical range. Our approach opens a new way to investigate and quantify the individual contribution of the three most important NIR continuum components observed in AGNs.

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arXiv2008

The Stellar Populations of Starburst Galaxies Through near infrared spectroscopy

We study the central (inner few hundred parsecs) stellar populations of four starburst galaxies (NGC34, NGC1614, NGC3310 and NGC7714) in the near-infrared (NIR), from 0.8 to 2.4microns, by fitting combinations of stellar population models of various ages and metallicities. The NIR spectra of these galaxies feature many absorption lines. For the first time, we fit simultaneously as much as 15 absorption features in the NIR. The observed spectra are best explained by stellar populations containing a sizable amount (20 to 56 % by mass) of ~1Gyr old stellar population with Thermally Pulsing-Asymptotic Giant Branch stars. We found that the metallicity of the stars which dominates the light is solar. Metallicities substantially different from solar give a worse fit. Though the ages and metallicities we estimate using the NIR spectroscopy are in agreement with values from the literature based on the UV/optical, we find older ages and a larger age spread. This may be due to the fact that the optical is mostly sensitive to the last episode of star formation, while the NIR better maintains the record of previous stellar generations. Another interesting result is that the reddening estimated from the whole NIR spectrum is considerably lower than that based on emission lines. Finally, we find a good agreement of the free emission line spectrum with photoionization models, using as input spectral energy distribution the synthetic composite template we derived as best-fit.

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arXiv2007

The first detection of near-infrared CN bands in active galactic nuclei: signature of star formation

We present the first detection of the near-infrared CN absorption band in the nuclear spectra of active galactic nuclei (AGN). This feature is a recent star formation tracer, being particularly strong in carbon stars. The equivalent width of the CN line correlates with that of the CO at 2.3 microns, as expected in stellar populations (SP) with ages between ~ 0.2 and ~ 2 Gyr. The presence of the 1.1 microns CN band in the spectra of the sources is taken as an unambiguous evidence of the presence of young/intermediate SP close to the central source of the AGN. Near-infrared bands can be powerful age indicators for star formation connected to AGN, the understanding of which is crucial in the context of galaxy formation and AGN feedback.

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arXiv2006

Optical and NIR spectroscopy of Mrk1210: constraints and physical conditions of the active nucleus

Near-infrared and optical spectroscopy of the nuclear and extended emission region of the Seyfert2 galaxy Mrk1210 is presented. This galaxy is outstanding because it displays signatures of recent circumnuclear star formation and a high-level of X-ray activity, in addition to the classical spectral characteristics typical of an AGN. The NIR nuclear spectrum, which covers the interval 0.8-2.4 microns, is dominated by HI and HeI recombination lines as well a [SII], [SIII] and [Fe II] forbidden lines. Coronal lines of [SVIII], [SIX], [SiVI], [SiX], and [CaVIII] in addition to molecular H_2 lines are also detected. An estimate of the contribution of the stellar population to the continuum is made by means of the ^{12}CO(6-3) 1.618 microns overtone bandhead. It was found that 83% of the H-band continuum is of stellar origin. It improves previous estimates, which claimed that at least 50% of the observed continuum was attributed to the AGN. The analysis of the emission line profiles, both allowed and forbidden, shows a narrower line on top of a broad blue-shifted component. The latter seems to be associated to a nuclear outflow. This result does not required the presence of a hidden BLR claimed to be present in previous NIR observations of this object. Internal extinction, calculated by means of several indicators including [FeII] flux ratios not previously used before in AGNs, reveals a dusty AGN, while the extended regions are little or not affected by dust. Density and temperature for the NLR are calculated using optical and NIR lines diagnostic ratios. The results show temperatures from 10000K up to 40000K and densities between 10^3-10^5 cm^{-3}. The larger temperatures points out that shocks must contribute to the line emission.

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arXiv2006

A 0.8-2.4 microns spectral atlas of Active Galactic Nuclei

Aims: We present a near-infrared spectral atlas of 47 active galactic nuclei (AGN), of all degrees of activity, in the wavelength interval of 0.8-2.4 microns, including the fluxes of the observed emission lines. We analyze the spectroscopic properties of the continuum and emission line spectra of the sources Methods: In order to exclude aperture and seeing effects we use near-infrared spectroscopy in the short cross-dispersed mode (SXD, 0.8-2.4 microns), taking the JHK-bands spectra simultaneously. Results: We present the most extensive NIR spectral atlas of AGN to date. This atlas offers a suitable database for studying the continuum and line emission properties of these objects in a region full of interesting features. The shape of the continuum of QSOs and Seyfert 1's are similar, being essentially flat in H and K band, in the J band, a strong variation is found. In Seyfert 2 galaxies, the continuum in the F_lambda X lambda space smoothly decreases from 1.2 microns redwards in almost all sources. In J, it smoothly rises bluewards in some sources while in others a small decreased in flux is observed. The spectra are dominated by strong emission features of H I, He I, He II, [S III] and conspicuous forbidden lines of low and high ionization species. Molecular lines of H2 are common features to most objects. The absence of O I and Fe II lines in Seyfert 2 galaxies give observational support to the fact that these lines are formated in the outermost portion of the broad line region. [P II] and coronal lines are detected in all degrees of activity. The [Fe II] 12570A/16436A line ratio becomes a reliable reddening indicator for the narrow-line region of Seyfert galaxies.

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arXiv2006

The near-infrared spectrum of Mrk 1239: direct evidence of the dusty torus?

We report 0.8-4.5 micron SpeX spectroscopy of the narrow-line Seyfert 1 galaxy Mrk1239. The spectrum is outstanding because the nuclear continuum emission in the near-infrared is dominated by a strong bump of emission peaking at 2.2 micron, with a strength not reported before in an AGN. A comparison of the Mrk1239 spectrum to that of Ark564 allowed us to conclude that the continuum is strongly reddened by E(B-V)=0.54. The excess of emission, confirmed by aperture photometry and additional NIR spectroscopy, follows a simple blackbody curve at T=1200 K. This suggest that we may be observing direct evidence of dust heated near to the sublimation temperature, likely produced by the putative torus of the unification model. Although other alternatives are also plausible, the lack of star formation, the strong polarization and low extinction derived for the emission lines support the scenario where the hot dust is located between the narrow line region and the broad line region.

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