ResearchOnline@JCU This file is part of the following reference: Castle, Ryan M. (2012) A radio and infrared investigation of Seyfert galaxies in the local universe. Masters (Research) thesis, James Cook University. Access to this file is available from: http://eprints.jcu.edu.au/29906/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://eprints.jcu.edu.au/29906/ A Radio and Infrared Investigation of Seyfert Galaxies in the Local Universe Thesis submitted by Ryan M. Castle, M.Sc. in August 2012 for the degree of M.Sc. from the Centre for Astronomy in the School of Engineering and Physical Sciences James Cook University THE CONTRIBUTION OF OTHERS David Blank, my one-time supervisor, suggested the initial research project of constructing a southern-sky sample of Seyferts and investigating their large-scale radio properties using the data from the SUMSS. Zhixin Peng, Department of Astronomy at Nanjing University, Nanjing, China, contributed to this work by providing a copy of an auxiliary computer file used (and described) in Chapter 3. 1 ACKNOWLEDGEMENTS I would like to thank my dear wife Karen for putting up with my diverted attention during my studies at JCU. 2 ABSTRACT Presented here are the results of an investigation of a newly constructed sample of local (z < 0.0303), southern-sky Seyfert galaxies. Data from the 843 MHz Sydney University Molonglo Sky Survey (SUMSS) was used, as well as near and mid/far-infrared data from the IRAS and 2MASS surveys, respectively. The first goal of this research was to construct a complete sample of southern-sky Seyferts for use in an ongoing study of this type of AGN in the local universe. The next and main research goal in this study was to search for any previously unidentified large-scale radio emission from the Seyferts - taking advantage of the good sensitivity and (u, v) plane coverage of the Molonglo Observatory Synthesis Telescope (MOST) used in the SUMSS. This was a search for extended radio emission that could perhaps identify past epochs of activity from the nucleus. In addition, this research enables another test the unified scheme for this type of AGN by carrying out several conventional two-sample statistical tests. Radio contour maps of all sample objects are presented as well as the distances, galactocentric recession velocities, and the 843 MHz, NIR (1.25, 1.65, 2.17 µm), and MID/FIR (12, 25, 60, 100 µm) luminosities. The IR data for this sample were also used to compute several spectral indices and the spectral energy distributions (SEDs) for the sample objects, as well as to investigate the global radio-FIR correlation known to exist among all galaxies. The most significant of the new results reported here include the identification of six radio-excess Seyferts, heretofore not identified as such in the literature, as well as a newly identified “radio- loud” type-2 Seyfert. Evidence for significant radio variability over a span of twenty years was also found for five of the sample objects by comparing data from the SUMSS to that from an earlier, smaller study using the MOST. In addition, the 2MASS Ks - band images of several of the closest type-2 Seyfert were decomposed into disk, bulge, and nuclear components in a study of the NIR properties of this type of active galaxy, increasing by nearly 50% the number of local Seyferts for which this type of analysis has been published. 3 TABLE OF CONTENTS Statement on the Contributions of Others...........................................................................................1 Acknowledgements.............................................................................................................................2 Abstract................................................................................................................................................3 Table of Contents.................................................................................................................................4 List of Tables.......................................................................................................................................6 List of Figures......................................................................................................................................7 Chapter 1: Introduction: A Review of the Literature 1.1 The Nature of Seyfert Galaxies........................................................................................9 1.2 Seyfert Types..................................................................................................................12 1.3 The Unified Scheme.......................................................................................................13 1.4 Radio Jets in AGN..........................................................................................................14 1.5 Radio Jets and Radio Variability....................................................................................16 1.6 Extended Radio Emission from Seyferts.......................................................................18 1.7 The Radio-FIR Correlation in Galaxies..........................................................................21 Chapter 2: A Southern-Sky Seyfert Sample & Its 843 MHz Radio Properties 2.1 The Sample....................................................................................................................27 2.2 The SUMSS....................................................................................................................33 2.3 Radio Maps & SUMSS Data for the Sample.................................................................35 2.4 Notes on Individual Objects...........................................................................................40 2.5 Results 2.5.1 Recession Velocities.......................................................................................63 2.5.2 Distances........................................................................................................65 2.5.3 The 843 MHz Luminosities............................................................................66 2.6 On the Completeness of the Sample..................................................................69 2.7 Statistical Tests..................................................................................................73 4 Chapter 3: Infrared Properties of the Sample 3.1 Some Notes on the IR Emission of Seyferts..................................................................74 3.2 The Surveys 3.2.1 The IRAS.........................................................................................................75 3.2.2 The 2MASS....................................................................................................77 3.3 The Data.........................................................................................................................78 3.4 The Determination of Upper Limits 3.4.1 IRAS Upper Limits.........................................................................................85 3.4.2 Sample Objects Not Covered by IRAS...........................................................89 3.4.3 2MASS Upper Limits.....................................................................................91 3.5 The IR Results 3.5.1 Flux Densities & Luminosities.......................................................................94 3.5.2 The Spectral Energy Distribution.................................................................105 3.5.3 Spectral Indices............................................................................................118 3.6 Statistical Tests.............................................................................................................123 3.7 The Radio versus Infrared Correlation.........................................................................126 3.8 Decomposition of 2MASS Ks -band Images................................................................137 Chapter 4: Discussion & Conclusions.............................................................................................140 Chapter 5: Summary & Future Work..............................................................................................151 Bibliography....................................................................................................................................153 Appendices Appendix A: Radio Contour Maps.....................................................................................169 Appendix B: Scanpi Output (Estimating Upper Limits)....................................................192 Appendix C: IR luminosities, errors, and log errors…………………..............................194 5 LIST OF TABLES Table 2.1: Basic properties of the Sy2 in the sample........................................................................................30 Table 2.2: Basic properties of the Sy1 in the sample........................................................................................32 Table 2.3: SUMSS Data for the Sy2..................................................................................................................37 Table 2.4: SUMSS Data for the Sy1..................................................................................................................39 Table 2.5: Summary