Hubble Spots Spirals Within a Spiral 13 April 2020, by Rob Garner

Total Page:16

File Type:pdf, Size:1020Kb

Hubble Spots Spirals Within a Spiral 13 April 2020, by Rob Garner Image: Hubble spots spirals within a spiral 13 April 2020, by Rob Garner way. These rings are not the only interesting feature of this galaxy. NGC 2273 is also a Seyfert galaxy, a galaxy with an extremely luminous core. In fact, the center of a galaxy such as this is powered by a supermassive black hole, and can glow brightly enough to outshine an entire galaxy like the Milky Way. Provided by NASA's Goddard Space Flight Center Credit: ESA/Hubble & NASA, J. Greene At first glance, the subject of this NASA/ESA Hubble Space Telescope image looks to be a simple spiral galaxy, with two pinwheeling arms emerging from a central bar of stars and material that cuts through the galactic center. In fact, there are rings within these spiral arms, too: spirals within a spiral. This kind of morphology is known as a multiring structure. As this description suggests, this galaxy, named NGC 2273, hosts an inner ring and two outer "pseudorings." Having so many distinct rings is rare and makes NGC 2273 unusual. Rings are created when a galaxy's spiral arms appear to loop around to nearly close upon one another, combined with a trick of cosmic perspective. NGC 2273's two pseudorings are formed by two swirling sets of spiral arms coming together, and the inner ring by two arcing structures nearer to the galactic center, which seem to connect in a similar 1 / 2 APA citation: Image: Hubble spots spirals within a spiral (2020, April 13) retrieved 1 October 2021 from https://phys.org/news/2020-04-image-hubble-spirals-spiral.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. 2 / 2 Powered by TCPDF (www.tcpdf.org).
Recommended publications
  • CO Multi-Line Imaging of Nearby Galaxies (COMING) IV. Overview Of
    Publ. Astron. Soc. Japan (2018) 00(0), 1–33 1 doi: 10.1093/pasj/xxx000 CO Multi-line Imaging of Nearby Galaxies (COMING) IV. Overview of the Project Kazuo SORAI1, 2, 3, 4, 5, Nario KUNO4, 5, Kazuyuki MURAOKA6, Yusuke MIYAMOTO7, 8, Hiroyuki KANEKO7, Hiroyuki NAKANISHI9 , Naomasa NAKAI4, 5, 10, Kazuki YANAGITANI6 , Takahiro TANAKA4, Yuya SATO4, Dragan SALAK10, Michiko UMEI2 , Kana MOROKUMA-MATSUI7, 8, 11, 12, Naoko MATSUMOTO13, 14, Saeko UENO9, Hsi-An PAN15, Yuto NOMA10, Tsutomu, T. TAKEUCHI16 , Moe YODA16, Mayu KURODA6, Atsushi YASUDA4 , Yoshiyuki YAJIMA2 , Nagisa OI17, Shugo SHIBATA2, Masumichi SETA10, Yoshimasa WATANABE4, 5, 18, Shoichiro KITA4, Ryusei KOMATSUZAKI4 , Ayumi KAJIKAWA2, 3, Yu YASHIMA2, 3, Suchetha COORAY16 , Hiroyuki BAJI6 , Yoko SEGAWA2 , Takami TASHIRO2 , Miho TAKEDA6, Nozomi KISHIDA2 , Takuya HATAKEYAMA4 , Yuto TOMIYASU4 and Chey SAITA9 1Department of Physics, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan 2Department of Cosmosciences, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan 3Department of Physics, School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan 4Division of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan 5Tomonaga Center for the History of the Universe (TCHoU), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan 6Department of Physical Science, Osaka Prefecture University, Gakuen 1-1,
    [Show full text]
  • Black Hole Mass Scaling Relations for Spiral Galaxies. I. MBH–M*,Sph Benjamin L
    The Astrophysical Journal, 873:85 (26pp), 2019 March 1 https://doi.org/10.3847/1538-4357/aaf3b8 © 2019. The American Astronomical Society. All rights reserved. Black Hole Mass Scaling Relations for Spiral Galaxies. I. MBH–M*,sph Benjamin L. Davis1 , Alister W. Graham1 , and Ewan Cameron2 1 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; [email protected] 2 Oxford Big Data Institute, University of Oxford, Oxford OX3 7LF, UK Received 2018 May 18; revised 2018 October 19; accepted 2018 November 13; published 2019 March 6 Abstract ( )–( ) The supermassive black hole mass, MBH bulge stellar mass, M*,sph relation is, obviously, derived using two quantities. We endeavor to provide accurate values for the latter via detailed multicomponent galaxy decompositions for the current full sample of 43 spiral galaxies having directly measured MBH values; 35 of these galaxies have been alleged to contain pseudobulges, 21 have water maser measurements, and three appear bulgeless. This more than doubles the previous sample size of spiral galaxies with a finessed image analysis. We have analyzed near-infrared images, accounting for not only the bulge, disk (exponential, truncated, or inclined), and bar but also spiral arms and rings and additional central components (active galactic nuclei (AGNs),etc.). A symmetric Bayesian analysis finds = +0.35 / 10 +( ± ) υ log (MMBH ☉) (2.44-0.31) log{M*,sph [u(1.15´ 10 M☉ )]} 7.24 0.12 ,with a stellar mass-to-light ratio term. The level of scatter equals that about the MBH–σ* relation. The nonlinear slope rules out the idea that many mergers, coupled with the central limit theorem, produced this scaling relation, and it corroborates previous observational studies and simulations, which have reported a near-quadratic slope at the low-mass end of the MBH– M ,sph diagram.
    [Show full text]
  • Accretion Disk Versus Jet Orientation in H2O Megamaser Galaxies F
    A&A 624, A42 (2019) Astronomy https://doi.org/10.1051/0004-6361/201834600 & c F. Kamali et al. 2019 Astrophysics Accretion disk versus jet orientation in H2O megamaser galaxies F. Kamali1;?, C. Henkel1,2, S. Koyama3,1, C. Y. Kuo4, J. J. Condon5, A. Brunthaler1, M. J. Reid6, J. E. Greene7, K. M. Menten1, C. M. V. Impellizzeri5,8, J. A. Braatz5, E. Litzinger9,10, and M. Kadler9 1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: [email protected], [email protected] 2 Astron. Dept., King Abdulaziz University, PO Box 80203, Jeddah 21589, Saudi Arabia 3 Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei 10617, Taiwan 4 Physics Department, National Sun Yat-Sen University, No. 70, Lien-Hai Rd, Kaosiung City 80424, Taiwan 5 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA 6 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 7 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA 8 Joint ALMA Office, Alonso de Córdova 3107, Vitacura, Santiago, Chile 9 Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Campus Hubland Nord, Emil-Fischer-Str. 31, 97074 Würzburg, Germany 10 Dr. Remeis-Observatory, Erlangen Centre for Astroparticle, Physics, University of Erlangen-Nuremberg, Sternwartstr. 7, 96049 Bamberg, Germany Received 7 November 2018 / Accepted 11 February 2019 ABSTRACT Context. An essential part of the paradigm describing active galactic nuclei is the alignment between the radio jet and the associated rotation axis of the sub-pc accretion disks.
    [Show full text]
  • Gas Accretion from Minor Mergers in Local Spiral Galaxies⋆
    A&A 567, A68 (2014) Astronomy DOI: 10.1051/0004-6361/201423596 & c ESO 2014 Astrophysics Gas accretion from minor mergers in local spiral galaxies? E. M. Di Teodoro1 and F. Fraternali1;2 1 Department of Physics and Astronomy, University of Bologna, 6/2, Viale Berti Pichat, 40127 Bologna, Italy e-mail: [email protected] 2 Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands Received 7 February 2014 / Accepted 28 May 2014 ABSTRACT We quantify the gas accretion rate from minor mergers onto star-forming galaxies in the local Universe using Hi observations of 148 nearby spiral galaxies (WHISP sample). We developed a dedicated code that iteratively analyses Hi data-cubes, finds dwarf gas-rich satellites around larger galaxies, and estimates an upper limit to the gas accretion rate. We found that 22% of the galaxies have at least one detected dwarf companion. We made the very stringent assumption that all satellites are going to merge in the shortest possible time, transferring all their gas to the main galaxies. This leads to an estimate of the maximum gas accretion rate of −1 0.28 M yr , about five times lower than the average star formation rate of the sample. Given the assumptions, our accretion rate is clearly an overestimate. Our result strongly suggests that minor mergers do not play a significant role in the total gas accretion budget in local galaxies. Key words. galaxies: interactions – galaxies: evolution – galaxies: kinematics and dynamics – galaxies: star formation – galaxies: dwarf 1. Introduction structures in the Universe grow by several inflowing events and have increased their mass content through a small number of The evolution of galaxies is strongly affected by their capabil- major mergers, more common at high redshifts, and through an ity of retaining their gas and accreting fresh material from the almost continuous infall of dwarf galaxies (Bond et al.
    [Show full text]
  • Nuclear Activity in Circumnuclear Ring Galaxies
    International Journal of Astronomy and Astrophysics, 2016, 6, 219-235 Published Online September 2016 in SciRes. http://www.scirp.org/journal/ijaa http://dx.doi.org/10.4236/ijaa.2016.63018 Nuclear Activity in Circumnuclear Ring Galaxies María P. Agüero1, Rubén J. Díaz2,3, Horacio Dottori4 1Observatorio Astronómico de Córdoba, UNCand CONICET, Córdoba, Argentina 2ICATE, CONICET, San Juan, Argentina 3Gemini Observatory, La Serena, Chile 4Instituto de Física, UFRGS, Porto Alegre, Brazil Received 23 May 2016; accepted 26 July 2016; published 29 July 2016 Copyright © 2016 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract We have analyzed the frequency and properties of the nuclear activity in a sample of galaxies with circumnuclear rings and spirals (CNRs), compiled from published data. From the properties of this sample a typical circumnuclear ring can be characterized as having a median radius of 0.7 kpc (mean 0.8 kpc, rms 0.4 kpc), located at a spiral Sa/Sb galaxy (75% of the hosts), with a bar (44% weak, 37% strong bars). The sample includes 73 emission line rings, 12 dust rings and 9 stellar rings. The sample was compared with a carefully matched control sample of galaxies with very similar global properties but without detected circumnuclear rings. We discuss the relevance of the results in regard to the AGN feeding processes and present the following results: 1) bright companion galaxies seem
    [Show full text]
  • 190 Index of Names
    Index of names Ancora Leonis 389 NGC 3664, Arp 005 Andriscus Centauri 879 IC 3290 Anemodes Ceti 85 NGC 0864 Name CMG Identification Angelica Canum Venaticorum 659 NGC 5377 Accola Leonis 367 NGC 3489 Angulatus Ursae Majoris 247 NGC 2654 Acer Leonis 411 NGC 3832 Angulosus Virginis 450 NGC 4123, Mrk 1466 Acritobrachius Camelopardalis 833 IC 0356, Arp 213 Angusticlavia Ceti 102 NGC 1032 Actenista Apodis 891 IC 4633 Anomalus Piscis 804 NGC 7603, Arp 092, Mrk 0530 Actuosus Arietis 95 NGC 0972 Ansatus Antliae 303 NGC 3084 Aculeatus Canum Venaticorum 460 NGC 4183 Antarctica Mensae 865 IC 2051 Aculeus Piscium 9 NGC 0100 Antenna Australis Corvi 437 NGC 4039, Caldwell 61, Antennae, Arp 244 Acutifolium Canum Venaticorum 650 NGC 5297 Antenna Borealis Corvi 436 NGC 4038, Caldwell 60, Antennae, Arp 244 Adelus Ursae Majoris 668 NGC 5473 Anthemodes Cassiopeiae 34 NGC 0278 Adversus Comae Berenices 484 NGC 4298 Anticampe Centauri 550 NGC 4622 Aeluropus Lyncis 231 NGC 2445, Arp 143 Antirrhopus Virginis 532 NGC 4550 Aeola Canum Venaticorum 469 NGC 4220 Anulifera Carinae 226 NGC 2381 Aequanimus Draconis 705 NGC 5905 Anulus Grahamianus Volantis 955 ESO 034-IG011, AM0644-741, Graham's Ring Aequilibrata Eridani 122 NGC 1172 Aphenges Virginis 654 NGC 5334, IC 4338 Affinis Canum Venaticorum 449 NGC 4111 Apostrophus Fornac 159 NGC 1406 Agiton Aquarii 812 NGC 7721 Aquilops Gruis 911 IC 5267 Aglaea Comae Berenices 489 NGC 4314 Araneosus Camelopardalis 223 NGC 2336 Agrius Virginis 975 MCG -01-30-033, Arp 248, Wild's Triplet Aratrum Leonis 323 NGC 3239, Arp 263 Ahenea
    [Show full text]
  • Making a Sky Atlas
    Appendix A Making a Sky Atlas Although a number of very advanced sky atlases are now available in print, none is likely to be ideal for any given task. Published atlases will probably have too few or too many guide stars, too few or too many deep-sky objects plotted in them, wrong- size charts, etc. I found that with MegaStar I could design and make, specifically for my survey, a “just right” personalized atlas. My atlas consists of 108 charts, each about twenty square degrees in size, with guide stars down to magnitude 8.9. I used only the northernmost 78 charts, since I observed the sky only down to –35°. On the charts I plotted only the objects I wanted to observe. In addition I made enlargements of small, overcrowded areas (“quad charts”) as well as separate large-scale charts for the Virgo Galaxy Cluster, the latter with guide stars down to magnitude 11.4. I put the charts in plastic sheet protectors in a three-ring binder, taking them out and plac- ing them on my telescope mount’s clipboard as needed. To find an object I would use the 35 mm finder (except in the Virgo Cluster, where I used the 60 mm as the finder) to point the ensemble of telescopes at the indicated spot among the guide stars. If the object was not seen in the 35 mm, as it usually was not, I would then look in the larger telescopes. If the object was not immediately visible even in the primary telescope – a not uncommon occur- rence due to inexact initial pointing – I would then scan around for it.
    [Show full text]
  • Ngc Catalogue Ngc Catalogue
    NGC CATALOGUE NGC CATALOGUE 1 NGC CATALOGUE Object # Common Name Type Constellation Magnitude RA Dec NGC 1 - Galaxy Pegasus 12.9 00:07:16 27:42:32 NGC 2 - Galaxy Pegasus 14.2 00:07:17 27:40:43 NGC 3 - Galaxy Pisces 13.3 00:07:17 08:18:05 NGC 4 - Galaxy Pisces 15.8 00:07:24 08:22:26 NGC 5 - Galaxy Andromeda 13.3 00:07:49 35:21:46 NGC 6 NGC 20 Galaxy Andromeda 13.1 00:09:33 33:18:32 NGC 7 - Galaxy Sculptor 13.9 00:08:21 -29:54:59 NGC 8 - Double Star Pegasus - 00:08:45 23:50:19 NGC 9 - Galaxy Pegasus 13.5 00:08:54 23:49:04 NGC 10 - Galaxy Sculptor 12.5 00:08:34 -33:51:28 NGC 11 - Galaxy Andromeda 13.7 00:08:42 37:26:53 NGC 12 - Galaxy Pisces 13.1 00:08:45 04:36:44 NGC 13 - Galaxy Andromeda 13.2 00:08:48 33:25:59 NGC 14 - Galaxy Pegasus 12.1 00:08:46 15:48:57 NGC 15 - Galaxy Pegasus 13.8 00:09:02 21:37:30 NGC 16 - Galaxy Pegasus 12.0 00:09:04 27:43:48 NGC 17 NGC 34 Galaxy Cetus 14.4 00:11:07 -12:06:28 NGC 18 - Double Star Pegasus - 00:09:23 27:43:56 NGC 19 - Galaxy Andromeda 13.3 00:10:41 32:58:58 NGC 20 See NGC 6 Galaxy Andromeda 13.1 00:09:33 33:18:32 NGC 21 NGC 29 Galaxy Andromeda 12.7 00:10:47 33:21:07 NGC 22 - Galaxy Pegasus 13.6 00:09:48 27:49:58 NGC 23 - Galaxy Pegasus 12.0 00:09:53 25:55:26 NGC 24 - Galaxy Sculptor 11.6 00:09:56 -24:57:52 NGC 25 - Galaxy Phoenix 13.0 00:09:59 -57:01:13 NGC 26 - Galaxy Pegasus 12.9 00:10:26 25:49:56 NGC 27 - Galaxy Andromeda 13.5 00:10:33 28:59:49 NGC 28 - Galaxy Phoenix 13.8 00:10:25 -56:59:20 NGC 29 See NGC 21 Galaxy Andromeda 12.7 00:10:47 33:21:07 NGC 30 - Double Star Pegasus - 00:10:51 21:58:39
    [Show full text]
  • XMM-Newton Observations of Seyfert Galaxies from the Palomar
    Astronomy & Astrophysics manuscript no. (will be inserted by hand later) XMM-Newton observations of Seyfert galaxies from the Palomar spectroscopic survey: the X-ray absorption distribution A. Akylas and I. Georgantopoulos Institute of Astronomy & Astrophysics, National Observatory of Athens, I.Metaxa & B. Pavlou, Penteli, 15236, Athens, Greece Abstract. We present XMM-Newton spectral analysis of all 38 Seyfert galaxies from the Palomar spectroscopic sample of galaxies. These are found at distances of up to 67 Mpc and cover the absorbed 2-10 keV luminosity range ∼ 1038 − 1043 erg s−1. Our aim is to determine the distribution of the X-ray absorption in the local Universe. Three of these are Compton-thick with column densities just above 1024 cm−2 and high equivalent width FeKα lines (> 700 eV). Five more sources have low values of the X-ray to [OIII] flux ratio suggesting that they could be associated with obscured nuclei. Their individual spectra show neither high absorbing columns nor 23 −2 flat spectral indices. However, their stacked spectrum reveals an absorbing column density of NH ∼ 10 cm . Therefore the fraction of absorbed sources (> 1022 cm−2) could be as high as 55 ± 12 %. A number of Seyfert-2 41 −1 appear to host unabsorbed nuclei. These are associated with low-luminosity sources LX < 3 × 10 erg s . Their stacked spectrum again shows no absorption while inspection of the Chandra images, where available, shows that contamination from nearby sources does not affect the XMM-Newton spectra in most cases. Nevertheless, such low luminosity sources are not contributing significantly to the X-ray background flux.
    [Show full text]
  • XMM-Newton Observations of Seyfert Galaxies from the Palomar Spectroscopic Survey: the X-Ray Absorption Distribution
    A&A 500, 999–1012 (2009) Astronomy DOI: 10.1051/0004-6361/200811371 & c ESO 2009 Astrophysics XMM-Newton observations of Seyfert galaxies from the Palomar spectroscopic survey: the X-ray absorption distribution A. Akylas and I. Georgantopoulos Institute of Astronomy & Astrophysics, National Observatory of Athens, I. Metaxa & B. Pavlou, Penteli, 15236 Athens, Greece Received 18 November 2008 / Accepted 16 March 2009 ABSTRACT We present XMM-Newton spectral analysis of all 38 Seyfert galaxies from the Palomar spectroscopic sample of galaxies. These are found at distances of up to 67 Mpc and cover the absorbed 2–10 keV luminosity range ∼1038–1043 erg s−1. Our aim is to determine the distribution of the X-ray absorption in the local Universe. Three of these are Compton-thick with column densities just above 24 −2 10 cm and high equivalent width FeKα lines (>700 eV). Five more sources have low values of the X-ray to [OIII] flux ratio suggesting that they could be associated with obscured nuclei. Their individual spectra show neither high absorbing columns nor flat 23 −2 spectral indices. However, their stacked spectrum reveals an absorbing column density of NH ∼ 10 cm . Therefore the fraction of absorbed sources (>1022 cm−2) could be as high as 55 ± 12%. A number of Seyfert-2 appear to host unabsorbed nuclei. These are 41 −1 associated with low-luminosity sources LX < 3 × 10 erg s . Their stacked spectrum again shows no absorption while inspection of the Chandra images, where available, shows that contamination from nearby sources does not affect the XMM-Newton spectra in most cases.
    [Show full text]
  • H-Alpha Imaging of Early-Type (Sa-Sab) Spiral Galaxies I
    Hα Imaging of Early-Type(Sa-Sab) Spiral Galaxies I1 Salman Hameed2, Nick Devereux2 Astronomy Department, New Mexico State University, Las Cruces, NM 88003 ABSTRACT Hα and continuum images are presented for 27 nearby early-type(Sa-Sab) spiral galaxies. Contrary to popular perception, the images reveal copious massive star formation in some of these galaxies. A determination of the Hα morphology and a measure of the Hα luminosity suggests that early-type spirals can be classified into two broad categories based on the luminosity of largest H II region in the disk. The first category includes galaxies for which the 39 −1 individual H II regions have LHα < 10 ergs . Most of the category 1 galaxies appear to be morphologically undisturbed, but show a wide diversity in nuclear Hα properties. The second category includes galaxies which have at least one 39 −1 H II region in the disk with LHα ≥ 10 ergs . All category 2 galaxies show either prominent dust lanes or other morphological peculiarities such as tidal tails which suggests that the anomalously luminous H II regions in category 2 galaxies may have formed as a result of a recent interaction. The observations, which are part of an on-going Hα survey, reveal early-type spirals to be a heterogeneous class of galaxies that are evolving in the current epoch. We have also identified some systematic differences between the classifications of spiral galaxies in the Second General Catalog (RC2) and the Revised Shapley- Ames Catalog (RSA) which may be traced to subtle variations in the application of the criteria used for classifying spiral galaxies.
    [Show full text]
  • On the X-Ray, Optical Emission Line and Black Hole Mass Properties of Local Seyfert Galaxies
    A&A 455, 173–185 (2006) Astronomy DOI: 10.1051/0004-6361:20064894 & c ESO 2006 Astrophysics On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies F. Panessa1, L. Bassani2, M. Cappi2,M.Dadina2,X.Barcons1, F. J. Carrera1,L.C.Ho3, and K. Iwasawa4 1 Instituto de Física de Cantabria (CSIC-UC), Avda. de los Castros, 39005 Santander, Spain e-mail: [email protected] 2 INAF – IASF, via P. Gobetti 101, 40129 Bologna, Italy 3 The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St. Pasadena, CA 91101, USA 4 Max Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstrasse 1, 85748 Garching, Germany Received 23 January 2006 / Accepted 4 May 2006 ABSTRACT We investigate the relation between X-ray nuclear emission, optical emission line luminosities and black hole masses for a sample of 47 Seyfert galaxies. The sample, which has been selected from the Palomar optical spectroscopic survey of nearby galaxies (Ho et al. 43 1997a, ApJS, 112, 315), covers a wide range of nuclear powers, from L2−10 keV ∼ 10 erg/s down to very low luminosities (L2−10 keV ∼ 1038 erg/s). Best available data from Chandra, XMM-Newton and, in a few cases, ASCA observations have been considered. Thanks to the good spatial resolution available from these observations and a proper modeling of the various spectral components, it has been possible to obtain accurate nuclear X-ray luminosities not contaminated by off-nuclear sources and/or diffuse emission. X-ray luminosities have then been corrected taking into account the likely candidate Compton thick sources, which are a high fraction (>30%) among type 2 Seyferts in our sample.
    [Show full text]