DSpace Collection:
http://hdl.handle.net/10261/416
2024-03-30T02:12:07ZThe origin of the optical intermediate classification of AGN
http://hdl.handle.net/10261/336124
Título: The origin of the optical intermediate classification of AGN
Autor: Barquín-González, Lorenzo; Carrera, Francisco J.; Mateos, Silvia; Corral, Amalia; Alonso-Herrero, A.
Resumen: The standard unification model of AGN assumes that optically obscured (Type 2) and unobscured (Type 1) can be explained with a clumpy structure of dust and gas - the torus - surrounding the central engine. For those AGN classified as intermediate types, the standard unification model assumes they are intermediate states of obscuration. However, this apparent change in extinction could be instead differences of other properties misinterpreted. These possible differences could be associated with the nuclear region of the AGN (a decreasing luminosity or BLR emission with intermediate class) or with properties of the host galaxy (an increasing luminosity or optical extinction).
To shed light on this issue, we have studied a unique sample of 165 X-ray selected AGN drawn from the Bright Ultra-hard XMM-Newton Survey (BUXS). The sources span more than 3 orders of magnitude in X-ray luminosity, from ~1e42 erg/s to ~1e45 erg/s, and redshifts from ~0.06 to 0.75. Of these, 117 sources have been spectroscopically classified as type 1 (98% with intermediate classification) and 48 as type 2. Thanks to the high-quality multi-wavelength data available for all sample objects, we have been able to determine their obscuration properties, host galaxy properties and the effect of AGN luminosity on the BLR and torus properties. The uniform selection, large sample size and high optical spectroscopic classification completeness assure us the derived results are statistically robust. We have found a clear increase in the observed optical extinction with intermediate classification. The same trend was confirmed using X-ray obscuration. At the same time, we have not found differences between host galaxy optical obscuration. Neither significant changes between AGN luminosities or BLR emission have been detected for intermediate classes. However, 1.8-9/2.0 AGN seem to live in more luminous galaxies than 1.0-1.5 AGN. Based on our results, we can conclude that extinction is the main driver of the intermediate classification, revealing 1.2/1.5/1.8 AGN as intermediate states of obscuration between type 1.0 and type 2. However, the highest luminosity of the host galaxies of type 1.9 and 2 becomes the dominant effect behind the classification origin for those of them with low extinction.
Descripción: Trabajo presentado al VI Meeting of AGN Research in Spain in the Era of the New Observatories el 30 de enero de 2023.2023-09-29T11:02:21ZRepresentative AGN spectral shapes for Automatic redshift extraction from X-ray AGN spectra
http://hdl.handle.net/10261/336121
Título: Representative AGN spectral shapes for Automatic redshift extraction from X-ray AGN spectra
Autor: Koushika, V. P.; Corral, Amalia; Carrera, Francisco J.; Laloux, Brivael; Akylas, Thanassis; Georgakakis, Antonis
Descripción: Trabajo presentado al VI Meeting of AGN Research in Spain in the Era of the New Observatories el 30 de enero de 2023.2023-09-29T10:53:31ZPlanetas y satélites: Viajando por el espacio
http://hdl.handle.net/10261/336117
Título: Planetas y satélites: Viajando por el espacio
Autor: Carrera, Francisco J.
Descripción: Trabajo presentado al XV Seminario Nacional EsTalMat el 11 de febrero de 2023.2023-09-29T10:42:22ZCosmic Birefringence: Searching for parity-violating physics with the polarization of the CMB
http://hdl.handle.net/10261/336113
Título: Cosmic Birefringence: Searching for parity-violating physics with the polarization of the CMB
Autor: Diego-Palazuelos, P.
Resumen: A violation of parity symmetry in electromagnetism would rotate the polarisation of the cosmic microwave background (CMB) in an effect known as cosmic birefringence. In the past, attempts to measure isotropic cosmic birefringence have been limited by the uncertainty in the calibration of the instrument's polarisation angle. In this talk I will present the novel methodology that allowed us to bypass that limitation by using Galactic foreground emission as our calibrator. Its application to WMAP and Planck data yields a birefringence angle of ß¿0.3º, with a statistical significance of 3¿. This measurement could be explained by a Chern-Simons coupling between photons and a pseudoscalar field like those predicted by ultra-light axionlike particles or Early Dark Energy. High-precision measurements of the CMB polarisation will allow us to distinguish between these two effects, potentially shedding more light on the Hubble tension.
Descripción: Trabajo presentado al CosmoVerse Online Seminar Series (CA21136).2023-09-29T10:32:16Z