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Large-Scale Environment of Low Luminosity Radio Loud Active Galactic Nuclei

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AperTO - Archivio Istituzionale Open Access dell'Università di Torino Large-scale environment of low luminosity radio loud Active Galactic Nuclei This is the author's manuscript Original Citation: Availability: This version is available http://hdl.handle.net/2318/1767392 since 2021-01-19T09:47:54Z Terms of use: Open Access Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law. (Article begins on next page) 27 September 2021 Università degli Studi di Torino Scuola di Dottorato in Scienza ed Alta Tecnologia Large-scale environment of low luminosity radio loud AGNs Nuria Álvarez Crespo Università degli Studi di Torino Scuola di Dottorato in Scienza ed Alta Tecnologia Dipartimento di Fisica, Via Pietro Giuria 1, Torino, Large-scale environment of low luminosity radio loud AGNs Nuria Álvarez Crespo Tutor: Francesco Massaro 2 Siempre le pedía a mi padre que me comprara un pájaro y él siempre me decía que lo que en realidad deseaba era la jaula. - El pájaro es la excusa - añadía. Juan José Millás iv Acknowledgements To my supervisor Prof. Massaro for guiding me and for giving me many opportunities to travel and to learn. I would like to thank my thesis committee: Dr. Paolillo, Dr. Risaliti and Dr. Mignone for their insightful comments and questions. I am also grateful to the University of Turin for funding the PhD research and giving me the opportunity to perform my research. To the great people that I met in Boston and to that conversations in the coffee room. To all the new friends made during this experience and in particular to my fellow doctoral students, for all the conversations, coffee and travels together. To the old ones for caring and never forgetting about me, even in the distance. To my family, my sister Inés, my parents Ramón and María Elena and my grandfather Alberto for all their support and encouragement. To the love of my life Juan for making me happy every day. You gave me strength and courage in the difficult times, and fun and joy in the easy ones. v vii Abstract Context: Active Galactic Nuclei (AGNs) are astrophysical sources located at the center of some galaxies, powered by accretion of matter into a supermassive black hole. About 10 % of these sources show jets, i.e., highly collimated outflows of ultrarelativistic particles that appear to originate at the central source, that extend for tens up to hundreds of kiloparsecs from the regions surrounding the black holes at their centres. The radio loud AGN Unification Model associates intrinsic low- luminosity radio galaxies (Fanaroff Riley type I, FR Is) with BL Lacs, being the former class the misaligned parent population of the latter since BL Lacs are considered to be FR Is but seen through their jets. BL Lacs are very strong γ-ray emitters, being the most numerous extragalactic sources at such high energies. Aims: According to the Unification Model, FR Is and BL Lacs must reside in similar environments. An extensive study of the FR Is large-scale environments has been performed by several authors throughout the years, and it is widely accepted that these objects tend to lie in galaxy groups or in moderately rich clusters. However, such systematic study of the clustering of galaxies around BL Lacs has not been performed yet, since only a handful of studies were devoted to this subject and to only a few objects, sometimes showing contradictory results. Here I present a compartive study of the environment of FR Is and BL Lacs. In addition, to improve statistics in the BL Lac study, it is important to find methods to discover new BL Lacs and measure their redshifts. Out of 3,033 sources in the latest release of the Fermi catalog ∼ 30% remain still unidentified, and since BL Lacs dominate the extragalactic γ-ray sky (∼ 30% of the associated sources), many of the unassociated sources could be BL Lacs. Moreover, about a 28% of the sources associated with a low energy counterpart show multifrequency behaviour similar to that of BL Lacs, but lack of spectroscopic information to confirm their classification, these are called Blazars of Uncertain type. Methods: The sample of FR Is was taken from a well defined sample in the FRICAT, while BL Lacs were selected from the Roma-BZCAT and sources classified as BL Lacs and BL Lacs with galactic spectra were studied separately. I selected those inside the footprint of the Sloan Digital Sky Survey (SDSS), and downloaded all the sources classified as galaxies inside a 2 Mpc radius from the FR I/BL Lac, and an analogous analysis was applied for both populations. A positional and redshift cross- match was performed with a catalog of galaxy clusters/groups in the SDSS, I measured the number of sources with a difference in their spectroscopic redshift from that of the central FR I/BL Lac ∆z < 0.005 inside that radius, and called them "cosmological neighbours". I also applied clustering algorithms to the photometric sources classified as galaxies in that 2 Mpc radius. Additionally, here I summarized results of the last 3 years of a spectroscopic campaign that started on 2012 to look for BL Lacs among Unidentified Gamma-ray Sources and Blazars of Uncertain Type in the latest release of the Fermi catalog. Results: About 70% of the FR Is were found in groups/clusters of galaxies but only ∼ 12% of the BL Lacs were found inside that same environment, strongly suggesting that both populations lie in different large-scale environments. Besides, ∼ 30% of the so-called "BL Lacs of galactic type" were found in galaxy rich environments, so there is a difference between the environments of these classes. In the optical spectroscopic campaign, a number of 188 spectra were analyzed, combining observations using 6 different telescopes with new data from optical surveys and literature, leading to the discovery of 132 new BL Lacs, proving the high efficiency of our selection strategy. Conclusions: Contrarily to what stated by the Unification Model, FR Is and BL Lacs reside in different environments, since most FR Is were found in groups/clusters of galaxies while BL Lacs do not tend to lie in galaxy rich large-scale environments. However, BL Lacs showing galactic spectrum lie in richer environments than BL Lacs but still not as rich as FR Is. Finally, about 70% of the sources observed during the last three years of our optical spectroscopic campaign were BL Lacs. Contents 1 Radio loud active galaxies1 1.1 Active Galactic Nuclei...................................1 1.2 Radio galaxies........................................3 1.2.1 Discovery and historical overview.........................3 1.2.2 Observational properties and theoretical interpretation.............4 1.2.3 Radio galaxy classification.............................4 1.3 Blazars............................................7 1.3.1 Discovery and historical overview.........................7 1.3.2 Blazar classification................................8 1.3.3 Observational properties and theoretical interpretation.............9 1.4 Unification Scenario for radio loud AGNs........................ 13 2 Environments 15 2.1 Groups and clusters of galaxies.............................. 15 2.2 The large-scale environments of RGs........................... 20 2.3 The large-scale environments of BL Lacs......................... 21 2.4 Open questions and scientific objectives......................... 27 3 Clustering analysis 31 3.1 Gnomonic projection.................................... 32 3.2 Clustering algorithms.................................... 33 3.2.1 DBSCAN + OPTICS............................... 33 3.2.2 Voronoi Tesselation................................. 38 3.2.3 Minimum Spanning Tree.............................. 40 4 Datasets and Catalogs 43 4.1 The Sloan Digital Sky Survey............................... 43 4.2 Catalogs of RGs and BL Lacs............................... 45 4.2.1 FRICAT....................................... 45 4.2.2 Roma-BZCAT................................... 46 ix x CONTENTS 4.2.3 Quiescent elliptical catalog............................ 48 4.2.4 Catalog of mock sources.............................. 48 4.3 Catalogs of groups and clusters of galaxies........................ 49 4.3.1 T12 catalog..................................... 49 4.3.2 GMBCG catalog.................................. 49 5 Environments of FR I Radio Galaxies 51 5.1 Comparing FRICAT with catalogs of clusters/groups of galaxies............ 51 5.1.1 Positional cross-matches FRICAT and T12 catalog............... 52 5.1.2 Positional cross-matches FRICAT and GMBCG catalog............ 52 5.1.3 Cosmological neighbors.............................. 52 5.1.4 Results....................................... 54 5.2 Clustering algorithms.................................... 59 5.2.1 DBSCAN + OPTICS............................... 60 5.2.2 Voronoi Tesselation................................. 61 5.2.3 Minimum Spanning Tree.............................. 62 5.3 Σk nearest neighbor.................................... 63 5.4 Conclusions......................................... 64 6 Environments of BL Lacs 67 6.1 Environments BL Lacs................................... 68 6.1.1 Positional cross-matches Roma-BZCAT and T12 catalog............ 68 6.1.2 Positional cross-matches Roma-BZCAT and GMBCG catalog......... 69 6.1.3 Cosmological neighbors.............................
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  • Introduction to Astronomy

    Introduction to Astronomy

    Introduction to Astronomy Prof. Sébastien R. A. Foucaud Department of Earth Sciences National Taiwan Normal University Unless noted, the course materials are licensed under Creative Commons 1 Attribution-NonCommercial-ShareAlike 3.0 Taiwan (CC BY-NC-SA 3.0) Credits: Chris Hetlage 2 Syllabus Astronomical techniques • Lecture 1: Finding its way on the night… • Lecture 2: Moving blindly and seeing the light… • Lecture 3: Eyes better than my eyes: the telescopes The solar system • Lecture 4: Home: Earth • Lecture 5: Our close friend: The Moon • Lecture 6: Our neighborhood: Rocky Planets • Lecture 7: The good Monsters: Giant Planets • Lecture 8: Dwarf Planets, minor bodies and scenario of solar system formation Stars and planets • Lecture 9: Our king: The Sun • Lecture 10: Shades of colors: so many stars… • Lecture 11: The life of a star: from its birth to its death • Lecture 12: The quest for another Earth: extrasolar planets The Milky-Way, galaxies and our Universe • Lecture 13: The cosmic carrousel: galactic structure & Galaxy formation • Lecture 14: Hubble, the expansion of the Universe and the Big-Bang Theory • Lecture 15: Einstein and the relativity 3 Lecture 13 The cosmic carrousel: galactic structure 4 Galaxies Spiral Galaxy NGC 253 Almost Sideways Credit & Copyright: Jean-Charles Cuillandre (CFHT) Hawaiian Starlight, CFHT APOD: 2003 May 25 • Star systems like our Milky Way •Few million to tens of billions of stars. • Large variety of shapes and sizes 5 Charles Messier (1730-1817) 6 M31 M51 M82 M82 New General Catalogue (NGC)/Johan Ludvig Emil Dreyer, William 7 Herschel, John Dunlop, Charles Messier M104 Messier Catalog, 1751 M31: The Andromeda Nebula 8 M51: The Whirlpool Galaxy 9 M82: An Exploding Galaxy 10 M1: The Crab Nebula 11 M57: The Ring Nebula 12 The Spiral Nebulae? • Nature unknown • Avoided the Milky Way • Immanuel Kant (1724 – 1804) speculated about “Island Universes”.