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The Local Radio-Galaxy Population at 20
Mon. Not. R. Astron. Soc. 000, 1–?? (2013) Printed 2 December 2013 (MN LATEX style file v2.2) The local radio-galaxy population at 20GHz Elaine M. Sadler1⋆, Ronald D. Ekers2, Elizabeth K. Mahony3, Tom Mauch4,5, Tara Murphy1,6 1Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006, Australia 2Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia 3ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo, The Netherlands 4Oxford Astrophysics, Department of Physics, Keble Road, Oxford OX1 3RH 5SKA Africa, 3rd Floor, The Park, Park Road, Pinelands, 7405, South Africa 6School of Information Technologies, The University of Sydney, NSW 2006, Australia Accepted 0000 December 08. Received 0000 December 08; in original form 0000 December 08 ABSTRACT We have made the first detailed study of the high-frequency radio-source population in the local universe, using a sample of 202 radio sources from the Australia Telescope 20GHz (AT20G) survey identified with galaxies from the 6dF Galaxy Survey (6dFGS). The AT20G- 6dFGS galaxies have a median redshift of z=0.058 and span a wide range in radio luminosity, allowing us to make the first measurement of the local radio luminosity function at 20GHz. Our sample includes some classical FR-1 and FR-2 radio galaxies, but most of the AT20G-6dFGS galaxies host compact (FR-0) radio AGN which appear lack extended radio emission even at lower frequencies. Most of these FR-0 sources show no evidence for rela- tivistic beaming, and the FR-0 class appears to be a mixed population which includes young Compact Steep-Spectrum (CSS) and Gigahertz-Peaked Spectrum (GPS) radio galaxies. -
A Multivariate Statistical Analysis of Spiral Galaxy Luminosities. I. Data and Results
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server A Multivariate Statistical Analysis of Spiral Galaxy Luminosities. I. Data and Results Alice Shapley California Institute of Technology, Pasadena CA, 91125, USA G. Fabbiano Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 P. B. Eskridge Ohio State University, Dept. of Astronomy, 140 W 18th Ave, Columbus, OH 43210 ABSTRACT We have performed a multiparametric analysis of luminosity data for a sample of 234 normal spiral and irregular galaxies observed in X-rays with the Einstein Observatory. This sample is representative of S and Irr galaxies, with a good coverage of morphological types and absolute magnitudes. In addition to X-ray and optical data, we have compiled H-band magnitudes, IRAS near- and far-infrared, and 6cm radio continuum observations for the sample from the literature. We have also performed a careful compilation of distance estimates. We have explored the effect of morphology by dividing the sample into early (S0/a-Sab), intermediate (Sb-Sbc), and late-type (Sc-Irr) subsamples. The data were analysed with bivariate and multivariate survival analysis techniques that make full use of all the information available in both detections and limits. We find that most pairs of luminosities are correlated when considered individually, and this is not due to a distance bias. Different luminosity-luminosity correlations follow different power-law relations. Contrary to previous reports, the LX LB correlation follows a power-law with exponent − larger than 1. Both the significances of some correlations and their power-law relations are morphology dependent. -
The Origin of the Iron Lines in NGC 7213
A&A 407, L21–L24 (2003) Astronomy DOI: 10.1051/0004-6361:20031054 & c ESO 2003 Astrophysics The origin of the iron lines in NGC 7213 S. Bianchi, G. Matt, I. Balestra, and G. C. Perola Dipartimento di Fisica, Universit`a degli Studi Roma Tre, Italy Received 20 June 2003 / Accepted 8 July 2003 Letter to the Editor Abstract. The analysis of a simultaneous XMM-Newton/BeppoSAX plus three previous BeppoSAX observations revealed that NGC 7213 is a rather peculiar Seyfert 1. No significant Compton reflection component was observed, while an iron line complex, best explained in terms of three narrow lines, is clearly apparent in the data. Due to the absence of the reflection component, the neutral iron line is likely not produced in a Compton-thick material, but current data do not allow to choose between a Compton-thin torus and the BLR. The two ionized iron lines from Fe xxv and Fe xxvi may be produced in a 23 2 photoionized gas with a column density of a few 10 cm− , in analogy with the case of NGC 5506. Key words. galaxies: individual: NGC 7213 – galaxies: Seyfert – X-rays: galaxies 1. Introduction the BeppoSAX PDS instrument. On the other hand, if the line is produced in the BLR, a much fainter Compton reflection Iron Kα emission lines are common features in Seyfert 1s. The component is expected, and the intrinsic width of the iron line profile of the line provides fundamental information on their should be the same as that of the optical broad lines. origin. If it is produced in the innermost regions of the accre- The nuclear activity of NGC 7213 (z = 0:005977) was tion disk, kinematic and relativistic effects contribute to forge discovered by the HEAO A-2 satellite (Marshall et al. -
Nov-Dec 2016.Pub
November-December 2016 Volume 64 The Observer Issue 7 The Newsletter of Central Valley Astronomers of Fresno In this Issue: Profiles in Astronomy-Abd al-Rahman al-Sufi The Guillermo Haro Obser- vatory More on the James Webb Telescope The Successor to Soyuz Elon Musk’s Plan to Send a Million People to Mars NASA is Worried about its Commercial Partners New Types of Gravitational Lenses found The Next Great Telescope The Caldwell Catalogue Starting in 2017, the world’s astronomical minds will be thinking about the James Webb Five Good Winter Objects Space Telescope, now in the final construction and testing stages. Scheduled for launch in 2018, to View it will be the most powerful and far-reaching instrument every developed(at least until its suc- _______________________ cessor, which is already being planned, comes along). More on the JWST inside (above-the JWST in the “clean room” at NASA’s Goddard Space Flight Center). Image from NASA/JWST Astronomy Quote of the Month In 1948, Albert Einstein was offered the presidency of the newly- established country of Israel (in Israel, unlike the U.S., the office of the president is appointive and mostly ceremonial). It was a reawakening of his Jewish roots, and he was honored by the offer, but declined it. He explained that he was too old and knew little about politics. A few years later, in ref- erence to the offer, he said, “Equations are more important to me, because politics are for the present, but an equation Two of the Caldwell ob- is for eternity.” jects: C 20 and C 94 From Stephen Hawking, -
Ira Sprague Bowen Papers, 1940-1973
http://oac.cdlib.org/findaid/ark:/13030/tf2p300278 No online items Inventory of the Ira Sprague Bowen Papers, 1940-1973 Processed by Ronald S. Brashear; machine-readable finding aid created by Gabriela A. Montoya Manuscripts Department The Huntington Library 1151 Oxford Road San Marino, California 91108 Phone: (626) 405-2203 Fax: (626) 449-5720 Email: [email protected] URL: http://www.huntington.org/huntingtonlibrary.aspx?id=554 © 1998 The Huntington Library. All rights reserved. Observatories of the Carnegie Institution of Washington Collection Inventory of the Ira Sprague 1 Bowen Papers, 1940-1973 Observatories of the Carnegie Institution of Washington Collection Inventory of the Ira Sprague Bowen Paper, 1940-1973 The Huntington Library San Marino, California Contact Information Manuscripts Department The Huntington Library 1151 Oxford Road San Marino, California 91108 Phone: (626) 405-2203 Fax: (626) 449-5720 Email: [email protected] URL: http://www.huntington.org/huntingtonlibrary.aspx?id=554 Processed by: Ronald S. Brashear Encoded by: Gabriela A. Montoya © 1998 The Huntington Library. All rights reserved. Descriptive Summary Title: Ira Sprague Bowen Papers, Date (inclusive): 1940-1973 Creator: Bowen, Ira Sprague Extent: Approximately 29,000 pieces in 88 boxes Repository: The Huntington Library San Marino, California 91108 Language: English. Provenance Placed on permanent deposit in the Huntington Library by the Observatories of the Carnegie Institution of Washington Collection. This was done in 1989 as part of a letter of agreement (dated November 5, 1987) between the Huntington and the Carnegie Observatories. The papers have yet to be officially accessioned. Cataloging of the papers was completed in 1989 prior to their transfer to the Huntington. -
Antony Hewish
PULSARS AND HIGH DENSITY PHYSICS Nobel Lecture, December 12, 1974 by A NTONY H E W I S H University of Cambridge, Cavendish Laboratory, Cambridge, England D ISCOVERY OF P U L S A R S The trail which ultimately led to the first pulsar began in 1948 when I joined Ryle’s small research team and became interested in the general problem of the propagation of radiation through irregular transparent media. We are all familiar with the twinkling of visible stars and my task was to understand why radio stars also twinkled. I was fortunate to have been taught by Ratcliffe, who first showed me the power of Fourier techniques in dealing with such diffraction phenomena. By a modest extension of existing theory I was able to show that our radio stars twinkled because of plasma clouds in the ionosphere at heights around 300 km, and I was also able to measure the speed of ionospheric winds in this region (1) . My fascination in using extra-terrestrial radio sources for studying the intervening plasma next brought me to the solar corona. From observations of the angular scattering of radiation passing through the corona, using simple radio interferometers, I was eventually able to trace the solar atmo- sphere out to one half the radius of the Earth’s orbit (2). In my notebook for 1954 there is a comment that, if radio sources were of small enough angular size, they would illuminate the solar atmosphere with sufficient coherence to produce interference patterns at the Earth which would be detectable as a very rapid fluctuation of intensity. -
Naming the Extrasolar Planets
Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named. -
ATNF News Issue No
Galaxy Pair NGC 1512 / NGC 1510 ATNF News Issue No. 67, October 2009 ISSN 1323-6326 Questacon "astronaut" street performer and visitors at the Parkes Open Days 2009. Credit: Shaun Amy, CSIRO. Cover page image Cover Figure: Multi-wavelength color-composite image of the galaxy pair NGC 1512/1510 obtained using the Digitised Sky Survey R-band image (red), the Australia Telescope Compact Array HI distribution (green) and the Galaxy Evolution Explorer NUV -band image (blue). The Spitzer 24µm image was overlaid just in the center of the two galaxies. We note that in the outer disk the UV emission traces the regions of highest HI column density. See article (page 28) for more information. 2 ATNF News, Issue 67, October 2009 Contents From the Director ...................................................................................................................................................................................................4 CSIRO Medal Winners .........................................................................................................................................................................................5 CSIRO Astronomy and Space Science Unit Formed ........................................................................................................................6 ATNF Distinguished Visitors Program ........................................................................................................................................................6 ATNF Graduate Student Program ................................................................................................................................................................7 -
The Search for Transiting Extrasolar Planets in the Open Cluster M52
THE SEARCH FOR TRANSITING EXTRASOLAR PLANETS IN THE OPEN CLUSTER M52 A Thesis Presented to the Faculty of San Diego State University In Partial Fulfillment of the Requirements for the Degree Master of Sciences in Astronomy by Tiffany M. Borders Summer 2008 SAN DIEGO STATE UNIVERSITY The Undersigned Faculty Committee Approves the Thesis of Tiffany M. Borders: The Search for Transiting Extrasolar Planets in the Open Cluster M52 Eric L. Sandquist, Chair Department of Astronomy William Welsh Department of Astronomy Calvin Johnson Department of Physics Approval Date iii Copyright 2008 by Tiffany M. Borders iv DEDICATION To all who seek new worlds. v Success is to be measured not so much by the position that one has reached in life as by the obstacles which he has overcome. –Booker T. Washington All the world’s a stage, And all the men and women merely players. They have their exits and their entrances; And one man in his time plays many parts... –William Shakespeare, “As You Like It”, Act 2 Scene 7 vi ABSTRACT OF THE THESIS The Search for Transiting Extrasolar Planets in the Open Cluster M52 by Tiffany M. Borders Master of Sciences in Astronomy San Diego State University, 2008 In this survey we attempt to discover short-period Jupiter-size planets in the young open cluster M52. Ten nights of R-band photometry were used to search for planetary transits. We obtained light curves of 4,128 stars and inspected them for variability. No planetary transits were apparent; however, some interesting variable stars were discovered. In total, 22 variable stars were discovered of which, 19 were not previously known as variable. -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
On the Relation Between Circular Velocity and Central Velocity Dispersion in High and Low Surface Brightness Galaxies1 A
The Astrophysical Journal, 631:785–791, 2005 October 1 A # 2005. The American Astronomical Society. All rights reserved. Printed in U.S.A. ON THE RELATION BETWEEN CIRCULAR VELOCITY AND CENTRAL VELOCITY DISPERSION IN HIGH AND LOW SURFACE BRIGHTNESS GALAXIES1 A. Pizzella,2 E. M. Corsini,2 E. Dalla Bonta`,2 M. Sarzi,3 L. Coccato,2 and F. Bertola2 Received 2005 January 5; accepted 2005 March 24 ABSTRACT In order to investigate the correlation between the circular velocity Vc and the central velocity dispersion of the spheroidal component c , we analyzed these quantities for a sample of 40 high surface brightness (HSB) disk galaxies, eight giant low surface brightness (LSB) spiral galaxies, and 24 elliptical galaxies characterized by flat À1 À1 rotation curves. Galaxies have been selected to have a velocity gradient 2kms kpc for R 0:35R25.Weused these data to better define the previous Vc-c correlation for spiral galaxies (which turned out to be HSB) and elliptical galaxies, especially at the lower end of the c values. We find that the Vc-c relation is described by a linear À1 law out to velocity dispersions as low as c 50 km s , while in previous works a power law was adopted for À1 galaxies with c > 80 km s . Elliptical galaxies with Vc based on dynamical models or directly derived from the H i rotation curves follow the same relation as the HSB galaxies in the Vc-c plane. On the other hand, the LSB galaxies follow a different relation, since most of them show either higher Vc or lower c with respect to the HSB galaxies. -
Flares on Active M-Type Stars Observed with XMM-Newton and Chandra
Flares on active M-type stars observed with XMM-Newton and Chandra Urmila Mitra Kraev Mullard Space Science Laboratory Department of Space and Climate Physics University College London A thesis submitted to the University of London for the degree of Doctor of Philosophy I, Urmila Mitra Kraev, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. Abstract M-type red dwarfs are among the most active stars. Their light curves display random variability of rapid increase and gradual decrease in emission. It is believed that these large energy events, or flares, are the manifestation of the permanently reforming magnetic field of the stellar atmosphere. Stellar coronal flares are observed in the radio, optical, ultraviolet and X-rays. With the new generation of X-ray telescopes, XMM-Newton and Chandra , it has become possible to study these flares in much greater detail than ever before. This thesis focuses on three core issues about flares: (i) how their X-ray emission is correlated with the ultraviolet, (ii) using an oscillation to determine the loop length and the magnetic field strength of a particular flare, and (iii) investigating the change of density sensitive lines during flares using high-resolution X-ray spectra. (i) It is known that flare emission in different wavebands often correlate in time. However, here is the first time where data is presented which shows a correlation between emission from two different wavebands (soft X-rays and ultraviolet) over various sized flares and from five stars, which supports that the flare process is governed by common physical parameters scaling over a large range.