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Trabajo presentado al XIV.0 Scientific Meeting (virtual) of the Spanish Astronomical Society (SEA), celebrado del13 al 15 de julio de 2020., The geometrical covering factor (f2) of the AGN nuclear absorber, the so-called "dusty torus", is substantially larger in optical type 2 AGN than in type 1 objects. We have investigated whether we observe the same effect for type 1 objects with increasing subtypes, from 1 to 1.9 to shed light onto the physical origin of the intermediate type classification of AGN: partial obscuration or an intrinsically weaker Broad Line Region at low AGN luminosities. Using a sample of 123 type 1 AGN with intermediate classification we have found that type 1.0, 1.2 and 1.5 AGN have similar distributions of f2 while objects classified as 1.8 and 1.9 have f2 values halfway between those of AGN types 1.0/1.2/1.5 and type 2s.

On behalf of the IFCA-Difusion group Instituto de Física de Cantabria (CSIC-UC)., Trabajo presentado al XIV.0 Scientific Meeting (virtual) of the Spanish Astronomical Society (SEA), celebrado del13 al 15 de julio de 2020., In the era of new technologies, in the Department of Public Outreach of the Instituto de Física de Cantabria we have added to our more purely digital catalog various materials and activities from the “manual” era, for which IFCA staff have developed their better DIY skills. From a planetary system to a (dis) mountable black hole, through a cloud chamber or a gravitational table, never forgetting the infallible ©LEGO, the manual materials have surprisingly aroused the interest of our public and visitors of all ages encouraging, in addition, the interdisciplinarity and team work of the members of the different IFCA research groups. From the IFCA PO department we have been able to verify how these types of materials have a great acceptance and are frequently required because they provide a complementary, more classical vision of the physical phenomena that we show in our activities. This presentation takes a tour of the materials that we have developed at IFCA, from the manufacturing process to their use and enjoyment, and will try to convince the audience of the therapeutic nature of building and, that an image is worth a thousand words but it is worth more than two thousand words if you have a gadget next to it., Funded by the Agencia Estatal de Investigación, Unidad de Excelencia María de Maeztu, ref. MDM-2017-0765.

Resumen del póster presentado al XIII Scientific Meeting of the Spanish Astronomical Society, celebrado en la Universidad de Salamanca del 16 al 20 de julio de 2018., According to the Unified Model of Active Galactic Nuclei (AGN), unobscured AGN based on its optical spectrum (detection of rest-frame UV-optical broad emission lines, type-1 AGN) should appear as X-ray unabsorbed AGN. However, there is an important fraction (10-30%) of AGN whose optical and X-ray classifications do not match, and the origin of the discrepancy is not clear. To provide insight into this topic, we have conducted a statistical analysis of the optical obscuration and X-ray absorption properties of the optically type1 AGN from the Bright Ultra-hard XMM-Newton Survey (BUXS) with L2−10keV >1042 erg s−1 and z=0.05-1. We have high-quality spectra from XMM-Newton and either SDSS spectra or proprietary observations for the selected sample. In order to provide the most complete sample as possible, we have conducted a detailed analysis of the emission lines to provide a reliable classification of the AGNs. We derive the X-ray absorption by fitting their XMM-Newton spectra and the optical extinction using UV/optical spectral continuum fits. As BUXS is a flux limited X-ray selected sample at hard energies (f4.510keV ≤6×10−14 ergs−1cm−2), it is complete for NH column densities up to the Compton-thick limit (∼1024cm−2). Our preliminary results show that most type-1 AGN in our sample show consistent optical and X-ray classification, but there is a large fraction ( 20%) of objects with large NH column densities (NH >4×1021 cm−2).

[Context]: The volume of data generated by astronomical surveys is growing rapidly. Traditional analysis techniques in spectroscopy either demand intensive human interaction or are computationally expensive. In this scenario, machine learning, and unsupervised clustering algorithms in particular, offer interesting alternatives. The Apache Point Observatory Galactic Evolution Experiment (APOGEE) offers a vast data set of near-infrared stellar spectra, which is perfect for testing such alternatives. [Aims]: Our research applies an unsupervised classification scheme based on K-means to the massive APOGEE data set. We explore whether the data are amenable to classification into discrete classes. [Methods]: We apply the K-means algorithm to 153 847 high resolution spectra (R ≈ 22 500). We discuss the main virtues and weaknesses of the algorithm, as well as our choice of parameters. [Results]: We show that a classification based on normalised spectra captures the variations in stellar atmospheric parameters, chemical abundances, and rotational velocity, among other factors. The algorithm is able to separate the bulge and halo populations, and distinguish dwarfs, sub-giants, RC, and RGB stars. However, a discrete classification in flux space does not result in a neat organisation in the parameters' space. Furthermore, the lack of obvious groups in flux space causes the results to be fairly sensitive to the initialisation, and disrupts the efficiency of commonly-used methods to select the optimal number of clusters. Our classification is publicly available, including extensive online material associated with the APOGEE Data Release 12 (DR12). [Conclusions]: Our description of the APOGEE database can help greatly with the identification of specific types of targets for various applications. We find a lack of obvious groups in flux space, and identify limitations of the K-means algorithm in dealing with this kind of data., We acknowledge financial support through grants, AYA2014-56359-P y AYA2017-86389-P and AYA2016-79724-C4-2-P (MINECO/FEDER). The research that leds to this article was partially funded by the Brazilian National Research Council (CNPq) through scholarship of the CSF program. CAP is thankful to the Spanish Government for funding for his research through grant AYA2014-56359-P. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science.

[Context]: The volume of data generated by astronomical surveys is growing rapidly. Traditional analysis techniques in spectroscopy either demand intensive human interaction or are computationally expensive. In this scenario, machine learning, and unsupervised clustering algorithms in particular, offer interesting alternatives. The Apache Point Observatory Galactic Evolution Experiment (APOGEE) offers a vast data set of near-infrared stellar spectra, which is perfect for testing such alternatives. [Aims]: Our research applies an unsupervised classification scheme based on K-means to the massive APOGEE data set. We explore whether the data are amenable to classification into discrete classes. [Methods]: We apply the K-means algorithm to 153 847 high resolution spectra (R ≈ 22 500). We discuss the main virtues and weaknesses of the algorithm, as well as our choice of parameters. [Results]: We show that a classification based on normalised spectra captures the variations in stellar atmospheric parameters, chemical abundances, and rotational velocity, among other factors. The algorithm is able to separate the bulge and halo populations, and distinguish dwarfs, sub-giants, RC, and RGB stars. However, a discrete classification in flux space does not result in a neat organisation in the parameters' space. Furthermore, the lack of obvious groups in flux space causes the results to be fairly sensitive to the initialisation, and disrupts the efficiency of commonly-used methods to select the optimal number of clusters. Our classification is publicly available, including extensive online material associated with the APOGEE Data Release 12 (DR12). [Conclusions]: Our description of the APOGEE database can help greatly with the identification of specific types of targets for various applications. We find a lack of obvious groups in flux space, and identify limitations of the K-means algorithm in dealing with this kind of data. We acknowledge financial support through grants, AYA2014-56359-P y AYA2017-86389-P and AYA2016-79724-C4-2-P (MINECO/FEDER). The research that leds to this article was partially funded by the Brazilian National Research Council (CNPq) through scholarship of the CSF program. CAP is thankful to the Spanish Government for funding for his research through grant AYA2014-56359-P. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science.

Mid-infrared (IR) colour selection techniques have proved to be very efficient in finding active galactic nuclei (AGN). This is because the AGN heats the surrounding dust producing warm mid-IR colours. Using the Wide-field Infrared Survey Explorer 3.6, 4.5 and 12 μm colours, the largest sample of IR selected AGN has already been produced containing 1.4 million AGN over the whole sky. Here, we explore the X-ray properties of this AGN sample by cross-correlating it with the subsample of the 3XMM X-ray catalogue that has available X-ray spectra and at the same time optical spectroscopy from Sloan Digital Sky Survey (SDSS). Our goal is to find rare luminous obscured AGN. Our final sample contains 65 QSOs with log vLv ≥ 46.2 erg s-1. This IR luminosity cut corresponds to log LX ≈ 45 erg s-1, at the median redshift of our sample (z = 2.3), that lies at the bright end of the X-ray luminosity function at z > 2. The X-ray spectroscopic analysis reveals seven obscured AGN having a column density NH > 1022 cm-2. Six of them show evidence for broad [C IV] absorption lines and five are classified as broad absorption line QSOs. We fit the optical spectra of our X-ray absorbed sources to estimate the optical reddening.We find that none of these show any obscuration according to the optical continuum. These sources add to the growing evidence for populations of luminous QSOs with evidence for substantial absorption by outflowing ionized material, similar to those expected to be emerging from their absorbing cocoons in the framework of AGN/galaxy co-evolution. © 2017 The Authors.

Approximately 3-17 per cent of active galactic nuclei (AGNs) without detected rest-frame UV/optical broad emission lines (type-2 AGN) do not show absorption in X-rays. The physical origin behind the apparently discordant optical/X-ray properties is not fully understood. Our study aims at providing insight into this issue by conducting a detailed analysis of the nuclear dust extinction and X-ray absorption properties of two AGNs with low X-ray absorption and with high optical extinction, for which a rich set of high-quality spectroscopic data is available from XMM-Newton archive data in X-rays and XSHOOTER proprietary data at UV-to-NIR wavelengths. In order to unveil the apparent mismatch, we have determined the AV/NH and both the supermassive black hole and the host galaxy masses. We find that the mismatch is caused in one case by an abnormally high dust-to-gas ratio that makes the UV/optical emission to appear more obscured than in the X-rays. For the other object, we find that the dust-to-gas ratio is similar to the Galactic one but the AGN is hosted by a very massive galaxy so that the broad emission lines and the nuclear continuum are swamped by the star light and difficult to detect., IO-P and FJC acknowledge financial support through grant AYA2015-64346-C2-1-P (MINECO/FEDER). SM acknowledges financial support by the Spanish Ministry of Economy and Competitiveness through grant AYA2016-76730-P (MINECO/FEDER). AC, RD, PS and VB acknowledge financial support by the Italian Space Agency (contract ASI-INAF I/037/12/0). Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society and the Higher Education Funding Council for England. The SDSS web site is http://www.sdss.org/. The STARLIGHT project is supported by the Brazilian agencies CNPq, CAPES and FAPESP and by the France-Brazil CAPES/Cofecub program.

Resumen del trabajo presentado al XXIX XMM-Newton SSC consortium meeting, celebrado en Madrid (España) del 14 al 15 de marzo de 2016., To provide insight into the apparent mismatch between the optical and X-ray absorption properties observed in 10-30 % of Active Galactic Nuclei (AGN), we have conducted a detailed study of two X-ray unabsorbed AGN with a type-2 optical spectroscopic classification. In addition to high quality X-ray spectroscopic observations, that we used to determine both the AGN luminosities and absorption, we have a VLT/XSHOOTER UV-to-near-IR high resolution spectrum for each object, that we used to determine the AGN intrinsic emision corrected for both contamination from the AGN hosts and extinction. Thanks to the high quality data available for these two intriguing sources, we unveil the origin of the mismatch. The most likely explanation is that both objects have an intrinsically high dust-to-gas ratio. In addition, we are conducting an statistical analysis of the optical obscuration and X-ray absorption properties of 159 Type-1 AGN drawn from BUXS to determine the distribution of dust-to-gas ratios in AGN over a broad range of luminosities and redshifts.

Trabajo presentado al XII Scientific Meeting of the Spanish Astronomical Society (SEA), celebrado en Bilbao del 18 al 22 de julio de 2016., According to the Unified Model of Active Galactic Nuclei (AGN), an X-ray unabsorbed AGN should appear as unobscured in the optical (Type-1) and viceversa (Type-2). However, there is an important fraction (10-30%) of AGN whose optical and X-ray classifications do not match. To provide insight into the origin of such apparent discrepancies, we have conducted two analyses: 1) a detailed study of the UV-to-near-IR emission of two X-ray unabsorbed Type-2 AGN drawn from the Bright Ultra-Hard XMM-Newton Survey (BUXS); 2) a statistical analysis of the optical obscuration and X-ray absorption properties of 159 Type-1 AGN drawn from BUXS to determine the distribution of dust-to-gas ratios in AGN over a broad range of luminosities and redshifts. In our works we have also determined the impact of contamination from the AGN hosts in the optical classification of AGNs. Our studies are already provided very exciting results such as the detection of objects with extreme dust-to-gas ratios, between 300-10000 times below the Galactic dust-to-gas ratio., IO-P and FJC acknowledge financial support through grant AYA2015-64346-C2-1-P (MINECO/FEDER). Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The STARLIGHT project is supported by the Brazilian agencies CNPq, CAPES and FAPESP and by the France-Brazil CAPES/Cofecub program.