Planck 2015 results. XXVIII. The Planck Catalogue of Galactic Cold Clumps

CERN Document Server

Ade, P.A.R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R.C.; Calabrese, E.; Catalano, A.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J.M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T.A.; Eriksen, H.K.; Falgarone, E.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A.A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Hurier, G.; Jaffe, A.H.; Jaffe, T.R.; Jones, W.C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T.S.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P.B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P.M.; Macías-Pérez, J.F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marshall, D.J.; Martin, P.G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; McGehee, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Nørgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Pasian, F.; Patanchon, G.; Pearson, T.J.; Pelkonen, V.-M.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G.W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J.P.; Reach, W.T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Stolyarov, V.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J.A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Wandelt, B.D.; Wehus, I.K.; Yvon, D.; Zacchei, A.

2016-01-01

We present the Planck Catalogue of Galactic Cold Clumps (PGCC), an all-sky catalogue of Galactic cold clump candidates detected by Planck. This catalogue is the full version of the Early Cold Core (ECC) catalogue, which was made available in 2011 with the Early Release Compact Source Catalogue (ERCSC) and contained 915 high S/N sources. It is based on the Planck 48 months mission data that are currently being released to the astronomical community. The PGCC catalogue is an observational catalogue consisting exclusively of Galactic cold sources. The three highest Planck bands (857, 545, 353 GHz) have been combined with IRAS data at 3 THz to perform a multi-frequency detection of sources colder than their local environment. After rejection of possible extragalactic contaminants, the PGCC catalogue contains 13188 Galactic sources spread across the whole sky, i.e., from the Galactic plane to high latitudes, following the spatial distribution of the main molecular cloud complexes. The median temperature of PGCC so...

Recent results on galactic sources with MAGIC telescope

International Nuclear Information System (INIS)

De los Reyes, R.

2009-01-01

Located at the Canary island of La Palma, the single-dish MAGIC telescope currently has the lowest energy threshold achieved by any Cherenkov telescope, which can be as low as 25 GeV. In the last two years, the MAGIC telescope has detected a significant amount of galactic sources that emit at very high energies (up to several TeV). Here we present the most recent results that have yielded important scientific highlights in astrophysics, which include the first detection of gamma-ray emission from a pulsar, an X-ray binary system and a stellar-mass black hole. We also make a review of the latest results of the MAGIC observations on galactic sources, which will include also γ-ray unidentified sources (TeV J2032+4130), the Galactic Centre, X-ray binaries (LSI +61 303), pulsars (Crab pulsar) and SNRs (IC443).

Planck 2015 results: XXVIII. The Planck Catalogue of Galactic cold clumps

DEFF Research Database (Denmark)

Ade, P. A R; Aghanim, N.; Arnaud, M.

2016-01-01

We present the Planck Catalogue of Galactic Cold Clumps (PGCC), an all-sky catalogue of Galactic cold clump candidates detected by Planck. This catalogue is the full version of the Early Cold Core (ECC) catalogue, which was made available in 2011 with the Early Release Compact Source Catalogue (E...

Candidate high-z protoclusters among the Planck compact sources, as revealed by Herschel-SPIRE

Science.gov (United States)

Greenslade, J.; Clements, D. L.; Cheng, T.; De Zotti, G.; Scott, D.; Valiante, E.; Eales, S.; Bremer, M. N.; Dannerbauer, H.; Birkinshaw, M.; Farrah, D.; Harrison, D. L.; Michałowski, M. J.; Valtchanov, I.; Oteo, I.; Baes, M.; Cooray, A.; Negrello, M.; Wang, L.; van der Werf, P.; Dunne, L.; Dye, S.

2018-05-01

By determining the nature of all the Planck compact sources within 808.4 deg2 of large Herschel surveys, we have identified 27 candidate protoclusters of dusty star-forming galaxies (DSFGs) that are at least 3σ overdense in either 250, 350, or 500 μm sources. We find roughly half of all the Planck compact sources are resolved by Herschel into multiple discrete objects, with the other half remaining unresolved by Herschel. We find a significant difference between versions of the Planck catalogues, with earlier releases hosting a larger fraction of candidate protoclusters and Galactic cirrus than later releases, which we ascribe to a difference in the filters used in the creation of the three catalogues. We find a surface density of DSFG candidate protoclusters of (3.3 ± 0.7) × 10-2 sources deg-2, in good agreement with previous similar studies. We find that a Planck colour selection of S857/S545 1. Our candidate protoclusters are a factor of 5 times brighter at 353 GHz than expected from simulations, even in the most conservative estimates. Further observations are needed to confirm whether these candidate protoclusters are physical clusters, multiple protoclusters along the line of sight, or chance alignments of unassociated sources.

Detection of extended galactic sources with an underwater neutrino telescope

International Nuclear Information System (INIS)

Leisos, A.; Tsirigotis, A. G.; Tzamarias, S. E.; Lenis, D.

2014-01-01

In this study we investigate the discovery capability of a Very Large Volume Neutrino Telescope to Galactic extended sources. We focus on the brightest HESS gamma rays sources which are considered also as very high energy neutrino emitters. We use the unbinned method taking into account both the spatial and the energy distribution of high energy neutrinos and we investigate parts of the Galactic plane where nearby potential neutrino emitters form neutrino source clusters. Neutrino source clusters as well as isolated neutrino sources are combined to estimate the observation period for 5 sigma discovery of neutrino signals from these objects

Observations of Galactic gamma-radiation with the SMM spectrometer

Science.gov (United States)

Share, G. H.; Kinzer, R. L.; Messina, D. C.; Purcell, W. R.; Chupp, E. L.

1986-01-01

Preliminary results from the SMM gamma-ray spectrometer are reported which indicate the detection of a constant source of 0.511-MeV annihilation radiation from the Galaxy. Year-to-year variability appears to be less than 30 percent. The radiation probably comes from a diffuse source and is not associated with the reported compact object at the Galactic center.

Galactic distribution of X-ray burst sources

International Nuclear Information System (INIS)

Lewin, W.H.G.; Hoffman, J.A.; Doty, J.; Clark, G.W.; Swank, J.H.; Becker, R.H.; Pravdo, S.H.; Serlemitsos, P.J.

1977-01-01

It is stated that 18 X-ray burst sources have been observed to date, applying the following definition for these bursts - rise times of less than a few seconds, durations of seconds to minutes, and recurrence in some regular pattern. If single burst events that meet the criteria of rise time and duration, but not recurrence are included, an additional seven sources can be added. A sky map is shown indicating their positions. The sources are spread along the galactic equator and cluster near low galactic longitudes, and their distribution is different from that of the observed globular clusters. Observations based on the SAS-3 X-ray observatory studies and the Goddard X-ray Spectroscopy Experiment on OSO-9 are described. The distribution of the sources is examined and the effect of uneven sky exposure on the observed distribution is evaluated. It has been suggested that the bursts are perhaps produced by remnants of disrupted globular clusters and specifically supermassive black holes. This would imply the existence of a new class of unknown objects, and at present is merely an ad hoc method of relating the burst sources to globular clusters. (U.K.)

X-ray bursters and the X-ray sources of the galactic bulge

International Nuclear Information System (INIS)

Lewin, W.H.G.; Joss, P.C.; Massachusetts Inst. of Tech., Cambridge; Massachusetts Inst. of Tech., Cambridge

1981-01-01

In this article we shall discuss the observed X-ray, optical, infrared and radio properties of the galactic bulge sources, with an emphasis on those that produce type I X-ray bursts. There is persuasive evidence that these burst sources and many other galactic bulge sources are neutron stars in low-mass, close-binary stellar systems. (orig./WL)

X-ray Studies of Unidentified Galactic TeV Gamma-ray Sources

Science.gov (United States)

Pühlhofer, Gerd

2009-05-01

Many of the recently discovered Galactic TeV sources remain unidentified to date. A large fraction of the sources is possibly associated with relic pulsar wind nebula (PWN) systems. One key question here is the maximum energy (beyond TeV) attained in the compact PWNe. Hard X-ray emission can trace those particles, but current non-focussing X-ray instruments above 10 keV have difficulties to deconvolve the hard pulsar spectrum from its surrounding nebula. Some of the new TeV sources are also expected to originate from middle-aged and possibly even from old supernova remnants (SNR). But no compelling case for such an identification has been found yet. In established young TeV-emitting SNRs, X-ray imaging above 10 keV could help to disentangle the leptonic from the hadronic emission component in the TeV shells, if secondary electrons produced in hadronic collisions can be effectively detected. As SNRs get older, the high energy electron component is expected to fade away. This may allow to verify the picture through X-ray spectral evolution of the source population. Starting from the lessons we have learned so far from X-ray follow-up observations of unidentified TeV sources, prospects for Simbol-X to resolve open questions in this field will be discussed.

X-ray Studies of Unidentified Galactic TeV Gamma-ray Sources

International Nuclear Information System (INIS)

Puehlhofer, Gerd

2009-01-01

Many of the recently discovered Galactic TeV sources remain unidentified to date. A large fraction of the sources is possibly associated with relic pulsar wind nebula (PWN) systems. One key question here is the maximum energy (beyond TeV) attained in the compact PWNe. Hard X-ray emission can trace those particles, but current non-focussing X-ray instruments above 10 keV have difficulties to deconvolve the hard pulsar spectrum from its surrounding nebula.Some of the new TeV sources are also expected to originate from middle-aged and possibly even from old supernova remnants (SNR). But no compelling case for such an identification has been found yet. In established young TeV-emitting SNRs, X-ray imaging above 10 keV could help to disentangle the leptonic from the hadronic emission component in the TeV shells, if secondary electrons produced in hadronic collisions can be effectively detected. As SNRs get older, the high energy electron component is expected to fade away. This may allow to verify the picture through X-ray spectral evolution of the source population.Starting from the lessons we have learned so far from X-ray follow-up observations of unidentified TeV sources, prospects for Simbol-X to resolve open questions in this field will be discussed.

H I absorption in nearby compact radio galaxies

Science.gov (United States)

Glowacki, M.; Allison, J. R.; Sadler, E. M.; Moss, V. A.; Curran, S. J.; Musaeva, A.; Deng, C.; Parry, R.; Sligo, M. C.

2017-05-01

H I absorption studies yield information on both active galactic nucleus (AGN) feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for H I absorption in a sample of 66 compact radio sources at 0.040 100 km s-1) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disc. Comparing mid-infrared colours of our galaxies with H I detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic discs. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of H I content within the host galaxy. This sample extends previous H I surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

Special issue on compact x-ray sources

Science.gov (United States)

Hooker, Simon; Midorikawa, Katsumi; Rosenzweig, James

2014-04-01

Journal of Physics B: Atomic, Molecular and Optical Physics is delighted to announce a forthcoming special issue on compact x-ray sources, to appear in the winter of 2014, and invites you to submit a paper. The potential for high-brilliance x- and gamma-ray sources driven by advanced, compact accelerators has gained increasing attention in recent years. These novel sources—sometimes dubbed 'fifth generation sources'—will build on the revolutionary advance of the x-ray free-electron laser (FEL). New radiation sources of this type have widespread applications, including in ultra-fast imaging, diagnostic and therapeutic medicine, and studies of matter under extreme conditions. Rapid advances in compact accelerators and in FEL techniques make this an opportune moment to consider the opportunities which could be realized by bringing these two fields together. Further, the successful development of compact radiation sources driven by compact accelerators will be a significant milestone on the road to the development of high-gradient colliders able to operate at the frontiers of particle physics. Thus the time is right to publish a peer-reviewed collection of contributions concerning the state-of-the-art in: advanced and novel acceleration techniques; sophisticated physics at the frontier of FELs; and the underlying and enabling techniques of high brightness electron beam physics. Interdisciplinary research connecting two or more of these fields is also increasingly represented, as exemplified by entirely new concepts such as plasma based electron beam sources, and coherent imaging with fs-class electron beams. We hope that in producing this special edition of Journal of Physics B: Atomic, Molecular and Optical Physics (iopscience.iop.org/0953-4075/) we may help further a challenging mission and ongoing intellectual adventure: the harnessing of newly emergent, compact advanced accelerators to the creation of new, agile light sources with unprecedented capabilities

Searching for axion-like particles with active-galactic nuclei

International Nuclear Information System (INIS)

Burrage, Clare; Davis, Anne-Christine; Shaw, Douglas J.

2009-12-01

Strong mixing between photons and axion-like particles in the magnetic fields of clusters of galaxies induces a scatter in the observed luminosities of compact sources in the cluster. This is used to construct a new test for axion-like particles; applied to observations of active galactic nuclei it is strongly suggestive of the existence of a light axion-like particle. (orig.)

Searching for axion-like particles with active-galactic nuclei

Energy Technology Data Exchange (ETDEWEB)

Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Davis, Anne-Christine [Centre for Mathematical Sciences, Cambridge (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics; Shaw, Douglas J. [Queen Mary Univ. of London (United Kingdom). Astronomy Unit, School of Mathematical Sciences

2009-12-15

Strong mixing between photons and axion-like particles in the magnetic fields of clusters of galaxies induces a scatter in the observed luminosities of compact sources in the cluster. This is used to construct a new test for axion-like particles; applied to observations of active galactic nuclei it is strongly suggestive of the existence of a light axion-like particle. (orig.)

INFLUENCE OF THE GALACTIC GRAVITATIONAL FIELD ON THE POSITIONAL ACCURACY OF EXTRAGALACTIC SOURCES

International Nuclear Information System (INIS)

Larchenkova, Tatiana I.; Lutovinov, Alexander A.; Lyskova, Natalya S.

2017-01-01

We investigate the influence of random variations of the Galactic gravitational field on the apparent celestial positions of extragalactic sources. The basic statistical characteristics of a stochastic process (first-order moments, an autocorrelation function and a power spectral density) are used to describe a light ray deflection in a gravitational field of randomly moving point masses as a function of the source coordinates. We map a 2D distribution of the standard deviation of the angular shifts in positions of distant sources (including reference sources of the International Celestial Reference Frame) with respect to their true positions. For different Galactic matter distributions the standard deviation of the offset angle can reach several tens of μ as (microarcsecond) toward the Galactic center, decreasing down to 4–6 μ as at high galactic latitudes. The conditional standard deviation (“jitter”) of 2.5 μ as is reached within 10 years at high galactic latitudes and within a few months toward the inner part of the Galaxy. The photometric microlensing events are not expected to be disturbed by astrometric random variations anywhere except the inner part of the Galaxy as the Einstein–Chvolson times are typically much shorter than the jittering timescale. While a jitter of a single reference source can be up to dozens of μ as over some reasonable observational time, using a sample of reference sources would reduce the error in relative astrometry. The obtained results can be used for estimating the physical upper limits on the time-dependent accuracy of astrometric measurements.

INFLUENCE OF THE GALACTIC GRAVITATIONAL FIELD ON THE POSITIONAL ACCURACY OF EXTRAGALACTIC SOURCES

Energy Technology Data Exchange (ETDEWEB)

Larchenkova, Tatiana I. [ASC of P.N.Lebedev Physical Institute, Leninskiy prospect 53, Moscow 119991 (Russian Federation); Lutovinov, Alexander A.; Lyskova, Natalya S. [Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation)

2017-01-20

We investigate the influence of random variations of the Galactic gravitational field on the apparent celestial positions of extragalactic sources. The basic statistical characteristics of a stochastic process (first-order moments, an autocorrelation function and a power spectral density) are used to describe a light ray deflection in a gravitational field of randomly moving point masses as a function of the source coordinates. We map a 2D distribution of the standard deviation of the angular shifts in positions of distant sources (including reference sources of the International Celestial Reference Frame) with respect to their true positions. For different Galactic matter distributions the standard deviation of the offset angle can reach several tens of μ as (microarcsecond) toward the Galactic center, decreasing down to 4–6 μ as at high galactic latitudes. The conditional standard deviation (“jitter”) of 2.5 μ as is reached within 10 years at high galactic latitudes and within a few months toward the inner part of the Galaxy. The photometric microlensing events are not expected to be disturbed by astrometric random variations anywhere except the inner part of the Galaxy as the Einstein–Chvolson times are typically much shorter than the jittering timescale. While a jitter of a single reference source can be up to dozens of μ as over some reasonable observational time, using a sample of reference sources would reduce the error in relative astrometry. The obtained results can be used for estimating the physical upper limits on the time-dependent accuracy of astrometric measurements.

Spectrometers for compact neutron sources

Science.gov (United States)

Voigt, J.; Böhm, S.; Dabruck, J. P.; Rücker, U.; Gutberlet, T.; Brückel, T.

2018-03-01

We discuss the potential for neutron spectrometers at novel accelerator driven compact neutron sources. Such a High Brilliance Source (HBS) relies on low energy nuclear reactions, which enable cryogenic moderators in very close proximity to the target and neutron optics at comparably short distances from the moderator compared to existing sources. While the first effect aims at increasing the phase space density of a moderator, the second allows the extraction of a large phase space volume, which is typically requested for spectrometer applications. We find that competitive spectrometers can be realized if (a) the neutron production rate can be synchronized with the experiment repetition rate and (b) the emission characteristics of the moderator can be matched to the phase space requirements of the experiment. MCNP simulations for protons or deuterons on a Beryllium target with a suitable target/moderator design yield a source brightness, from which we calculate the sample fluxes by phase space considerations for different types of spectrometers. These match closely the figures of todays spectrometers at medium flux sources. Hence we conclude that compact neutron sources might be a viable option for next generation neutron sources.

Theoretical galactic cosmic ray electron spectrum obtained for sources of varying geometry

International Nuclear Information System (INIS)

Cohen, M.E.

1969-01-01

Jokipii and Meyer have recently obtained an electron density energy spectrum of the cosmic rays, originating in the Galaxy, using integral solutions of the steady state transfer equations, by considering a circular cylindric galactic disc as source and approximating the resulting fourth order integral. In this report, we present general results, obtained by using an arbitrary circular cylindric source, without restricting ourselves to the galactic disc. The integrals are treated exactly. The conclusions of Jokipii and Meyer form special cases of these results. We also obtain an exponential energy variation which, at the moment, is not observed experimentally. The second part of this work deals with more complicated, but perhaps more realistic models of elliptic cylindric and ellipsoidal galactic disc sources. One may also note that a very large source concentrated in a very small region gives a spectrum not unlike that for a small source distributed throughout a large volume. Finally, it may be remarked that the model adopted is much less restrictive than the artificial conception of 'leakage time' followed by other workers. (author) [fr

Accretion Disk Spectra of the Ultra-Luminous X-Ray Sources in Nearby Spiral Galaxies and Galactic Superluminal Jet Sources

Energy Technology Data Exchange (ETDEWEB)

Mizuno, T

2003-12-11

Ultra-luminous Compact X-ray Sources (ULXs) in nearby spiral galaxies and Galactic superluminal jet sources share the common spectral characteristic that they have unusually high disk temperatures which cannot be explained in the framework of the standard optically thick accretion disk in the Schwarzschild metric. On the other hand, the standard accretion disk around the Kerr black hole might explain the observed high disk temperature, as the inner radius of the Kerr disk gets smaller and the disk temperature can be consequently higher. However, we point out that the observable Kerr disk spectra becomes significantly harder than Schwarzschild disk spectra only when the disk is highly inclined. This is because the emission from the innermost part of the accretion disk is Doppler-boosted for an edge-on Kerr disk, while hardly seen for a face-on disk. The Galactic superluminal jet sources are known to be highly inclined systems, thus their energy spectra may be explained with the standard Kerr disk with known black hole masses. For ULXs, on the other hand, the standard Kerr disk model seems implausible, since it is highly unlikely that their accretion disks are preferentially inclined, and, if edge-on Kerr disk model is applied, the black hole mass becomes unreasonably large (> 300 M{sub solar}). Instead, the slim disk (advection dominated optically thick disk) model is likely to explain the observed super-Eddington luminosities, hard energy spectra, and spectral variations of ULXs. We suggest that ULXs are accreting black holes with a few tens of solar mass, which is not unexpected from the standard stellar evolution scenario, and that their X-ray emission is from the slim disk shining at super-Eddington luminosities.

Galactic Sources Detected in the NuSTAR Serendipitous Survey

Energy Technology Data Exchange (ETDEWEB)

Tomsick, John A.; Clavel, Maïca; Chiu, Jeng-Lun [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Lansbury, George B.; Aird, James [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Rahoui, Farid [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States); Fornasini, Francesca M.; Hong, JaeSub; Grindlay, Jonathan E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Alexander, David M. [Centre for Extragalactic Astronomy, Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Bodaghee, Arash [Georgia College and State University, Milledgeville, GA 31061 (United States); Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Harrison, Fiona A. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Krivonos, Roman A. [Space Research Institute of the Russian Academy of Sciences, Profsoyuznaya Str. 84/32, 117997, Moscow (Russian Federation); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

2017-06-01

The Nuclear Spectroscopic Telescope Array (NuSTAR) provides an improvement in sensitivity at energies above 10 keV by two orders of magnitude over non-focusing satellites, making it possible to probe deeper into the Galaxy and universe. Lansbury and collaborators recently completed a catalog of 497 sources serendipitously detected in the 3–24 keV band using 13 deg{sup 2} of NuSTAR coverage. Here, we report on an optical and X-ray study of 16 Galactic sources in the catalog. We identify 8 of them as stars (but some or all could have binary companions), and use information from Gaia to report distances and X-ray luminosities for 3 of them. There are 4 CVs or CV candidates, and we argue that NuSTAR J233426–2343.9 is a relatively strong CV candidate based partly on an X-ray spectrum from XMM-Newton . NuSTAR J092418–3142.2, which is the brightest serendipitous source in the Lansbury catalog, and NuSTAR J073959–3147.8 are low-mass X-ray binary candidates, but it is also possible that these 2 sources are CVs. One of the sources is a known high-mass X-ray binary (HMXB), and NuSTAR J105008–5958.8 is a new HMXB candidate that has strong Balmer emission lines in its optical spectrum and a hard X-ray spectrum. We discuss the implications of finding these HMXBs for the surface density (log N –log S ) and luminosity function of Galactic HMXBs. We conclude that with the large fraction of unclassified sources in the Galactic plane detected by NuSTAR in the 8–24 keV band, there could be a significant population of low-luminosity HMXBs.

Detection of a compact radio source near the center of a gravitational lens: quasar image or galactic core

International Nuclear Information System (INIS)

Gorenstein, M.V.; Shapiro, I.I.; Cohen, N.L.

1983-01-01

By use of a new, very sensitive interferometric system, a faint, compact radio source has been detected near the center of the galaxy that acts as the main part of a gravitational lens. This lens forms two previously discovered images of the quasar Q0957 + 561, which lies in the direction of the constellation Ursa Major. The newly detected source has a core smaller than 0.002 arc second in diameter with a flux density of 0.6 +- 0.1 millijansky at the 13-centimeter wavelength of the radio observations. This source could be the predicted third image of the transparent gravitational lens, the central core of the galaxy, or some combination of the two. It is not yet possible to choose reliably between these alternatives

Cosmic ray injection spectrum at the galactic sources

Science.gov (United States)

Lagutin, Anatoly; Tyumentsev, Alexander; Volkov, Nikolay

The spectra of cosmic rays measured at Earth are different from their source spectra. A key to understanding this difference, being crucial for solving the problem of cosmic-ray origin, is the determination of how cosmic-ray (CR) particles propagate through the turbulent interstellar medium (ISM). If the medium is a quasi-homogeneous the propagation process can be described by a normal diffusion model. However, during a last few decades many evidences, both from theory and observations, of the existence of multiscale structures in the Galaxy have been found. Filaments, shells, clouds are entities widely spread in the ISM. In such a highly non-homogeneous (fractal-like) ISM the normal diffusion model certainly is not kept valid. Generalization of this model leads to what is known as "anomalous diffusion". The main goal of the report is to retrieve the cosmic ray injection spectrum at the galactic sources in the framework of the anomalous diffusion (AD) model. The anomaly in this model results from large free paths ("Levy flights") of particles between galactic inhomogeneities. In order to evaluate the CR spectrum at the sources, we carried out new calculation of the CR spectra at Earth. AD equation in terms of fractional derivatives have been used to describe CR propagation from the nearby (r≤1 kpc) young (t≤ 1 Myr) and multiple old distant (r > 1 kpc) sources. The assessment of the key model parameters have been based on the results of the particles diffusion in the cosmic and laboratory plasma. We show that in the framework of the anomalous diffusion model the locally observed basic features of the cosmic rays (difference between spectral exponents of proton, He and other nuclei, "knee" problem, positron to electron ratio) can be explained if the injection spectrum at the main galactic sources of cosmic rays has spectral exponent p˜ 2.85. The authors acknowledge support from The Russian Foundation for Basic Research grant No. 14-02-31524.

THE ARECIBO METHANOL MASER GALACTIC PLANE SURVEY. IV. ACCURATE ASTROMETRY AND SOURCE MORPHOLOGIES

International Nuclear Information System (INIS)

Pandian, J. D.; Momjian, E.; Xu, Y.; Menten, K. M.; Goldsmith, P. F.

2011-01-01

We present accurate absolute astrometry of 6.7 GHz methanol masers detected in the Arecibo Methanol Maser Galactic Plane Survey using MERLIN and the Expanded Very Large Array (EVLA). We estimate the absolute astrometry to be accurate to better than 15 and 80 mas for the MERLIN and EVLA observations, respectively. We also derive the morphologies of the maser emission distributions for sources stronger than ∼1 Jy. The median spatial extent along the major axis of the regions showing maser emission is ∼775 AU. We find a majority of methanol maser morphologies to be complex with some sources previously determined to have regular morphologies in fact being embedded within larger structures. This suggests that some maser spots do not have a compact core, which leads to them being resolved in high angular resolution observations. This also casts doubt on interpretations of the origin of methanol maser emission solely based on source morphologies. We also investigate the association of methanol masers with mid-infrared emission and find very close correspondence between methanol masers and 24 μm point sources. This adds further credence to theoretical models that predict methanol masers to be pumped by warm dust emission and firmly reinforces the finding that Class II methanol masers are unambiguous tracers of embedded high-mass protostars.

Active galactic nuclei cores in infrared-faint radio sources. Very long baseline interferometry observations using the Very Long Baseline Array

Science.gov (United States)

Herzog, A.; Middelberg, E.; Norris, R. P.; Spitler, L. R.; Deller, A. T.; Collier, J. D.; Parker, Q. A.

2015-06-01

Context. Infrared-faint radio sources (IFRS) form a new class of galaxies characterised by radio flux densities between tenths and tens of mJy and faint or absent infrared counterparts. It has been suggested that these objects are radio-loud active galactic nuclei (AGNs) at significant redshifts (z ≳ 2). Aims: Whereas the high redshifts of IFRS have been recently confirmed based on spectroscopic data, the evidence for the presence of AGNs in IFRS is mainly indirect. So far, only two AGNs have been unquestionably confirmed in IFRS based on very long baseline interferometry (VLBI) observations. In this work, we test the hypothesis that IFRS contain AGNs in a large sample of sources using VLBI. Methods: We observed 57 IFRS with the Very Long Baseline Array (VLBA) down to a detection sensitivity in the sub-mJy regime and detected compact cores in 35 sources. Results: Our VLBA detections increase the number of VLBI-detected IFRS from 2 to 37 and provide strong evidence that most - if not all - IFRS contain AGNs. We find that IFRS have a marginally higher VLBI detection fraction than randomly selected sources with mJy flux densities at arcsec-scales. Moreover, our data provide a positive correlation between compactness - defined as the ratio of milliarcsec- to arcsec-scale flux density - and redshift for IFRS, but suggest a decreasing mean compactness with increasing arcsec-scale radio flux density. Based on these findings, we suggest that IFRS tend to contain young AGNs whose jets have not formed yet or have not expanded, equivalent to very compact objects. We found two IFRS that are resolved into two components. The two components are spatially separated by a few hundred milliarcseconds in both cases. They might be components of one AGN, a binary black hole, or the result of gravitational lensing.

Supernova Remnants as the Sources of Galactic Cosmic Rays

NARCIS (Netherlands)

Vink, J.

2013-01-01

The origin of cosmic rays holds still manymysteries hundred years after they were first discovered. Supernova remnants have for long been the most likely sources of Galactic cosmic rays. I discuss here some recent evidence that suggests that supernova remnants can indeed efficiently accelerate

Compact reactor/ORC power source

International Nuclear Information System (INIS)

Meier, K.L.; Kirchner, W.L.; Willcutt, G.J.

1986-01-01

A compact power source that combines an organic Rankine Cycle (ORC) electric generator with a nuclear reactor heat source is being designed and fabricated. Incorporating existing ORC technology with proven reactor technology, the compact reactor/ORC power source offers high reliability while minimizing the need for component development. Thermal power at 125 kWt is removed from the coated particle fueled, graphite moderated reactor by heat pipes operating at 500 0 C. Outside the reactor vessel and connected to the heat pipes are vaporizers in which the toluene ORC working fluid is heated to 370 0 C. In the turbine-alternator-pump (TAP) combined-rotating unit, the thermal energy of the toluene is converted to 25 kWe of electric power. Lumped parameter systems analyses combined with a finite element thermal analysis have aided in the power source design. The analyses have provided assurance of reliable multiyear normal operation as well as full power operation with upset conditions, such as failed heat pipes and inoperative ORC vaporizers. Because of inherent high reliability, long life, and insensitivity to upset conditions, this power source is especially suited for use in remote, inaccessible locations where fuel delivery and maintenance costs are high. 10 refs

Galactic sources of high energy neutrinos: Expectation from gamma-ray data

Directory of Open Access Journals (Sweden)

Sahakyan N.

2016-01-01

Full Text Available The recent results from ground based γ-ray detectors (HESS, MAGIC, VERITAS provide a population of TeV galactic γ-ray sources which are potential sources of High Energy (HE neutrinos. Since the γ-rays and ν-s are produced from decays of neutral and charged pions, the flux of TeV γ-rays can be used to estimate the upper limit of ν flux and vice versa; the detectability of ν flux implies a minimum flux of the accompanying γ-rays (assuming the internal and the external absorption of γ-rays is negligible. Using this minimum flux, it is possible to find the sources which can be detected with cubic-kilometer telescopes. I will discuss the possibility to detect HE neutrinos from powerful galactic accelerators, such as Supernova Remnants (SNRs and Pulsar Wind Nebulae (PWNe and show that likely only RX J1713.7-3946, RX J0852.0-4622 and Vela X can be detected by current generation of instruments (IceCube and Km3Net. It will be shown also, that galactic binary systems could be promising sources of HE ν-s. In particular, ν-s and γ-rays from Cygnus X-3 will be discussed during recent gamma-ray activity, showing that in the future such kind of activities could produce detectable flux of HE ν-s.

Progress of compact Marx generators high power microwave source

International Nuclear Information System (INIS)

Liu Jinliang; Fan Xuliang; Bai Guoqiang; Cheng Xinbing

2012-01-01

The compact Marx generators, which can operate at a certain repetition frequency with small size, light weight, and high energy efficiency, are widely used in narrowband, wideband and ultra-wideband high power microwave (HPM) sources. This type of HPM source based on compact Marx generators is a worldwide research focus in recent years, and is important trend of development. The developments of this type of HPM source are described systemically in this paper. The output parameters and structural characteristics are reviewed, and the trends of development are discussed. This work provides reference and evidence for us to master the status of the HPM source based on compact Marx generators correctly and to explore its technical routes scientifically. (authors)

Insights into the Galactic Cosmic-ray Source from the TIGER Experiment

Science.gov (United States)

Link, Jason T.; Barbier, L. M.; Binns, W. R.; Christian, E. R.; Cummings, J. R.; Geier, S.; Israel, M. H.; Lodders, K.; Mewaldt,R. A.; Mitchell, J. W.;

Searching for Compact Radio Sources Associated with UCH ii Regions

Energy Technology Data Exchange (ETDEWEB)

Masqué, Josep M.; Trinidad, Miguel A.; Rodríguez-Rico, Carlos A. [Departamento de Astronomía, Universidad de Guanajuato, Apdo. Postal 144, 36000 Guanajuato, México (Mexico); Rodríguez, Luis F.; Kurtz, Stan; Loinard, Laurent [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia 58089, México (Mexico); Dzib, Sergio A. [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

2017-02-10

Ultra-compact (UC)H ii regions represent a very early stage of massive star formation. The structure and evolution of these regions are not yet fully understood. Interferometric observations showed in recent years that compact sources of uncertain nature are associated with some UCH ii regions. To examine this, we carried out VLA 1.3 cm observations in the A configuration of selected UCH ii regions in order to report additional cases of compact sources embedded in UCH ii regions. With these observations, we find 13 compact sources that are associated with 9 UCH ii regions. Although we cannot establish an unambiguous nature for the newly detected sources, we assess some of their observational properties. According to the results, we can distinguish between two types of compact sources. One type corresponds to sources that are probably deeply embedded in the dense ionized gas of the UCH ii region. These sources are photoevaporated by the exciting star of the region and will last for 10{sup 4}–10{sup 5} years. They may play a crucial role in the evolution of the UCH ii region as the photoevaporated material could replenish the expanding plasma and might provide a solution to the so-called lifetime problem of these regions. The second type of compact sources is not associated with the densest ionized gas of the region. A few of these sources appear resolved and may be photoevaporating objects such as those of the first type, but with significantly lower mass depletion rates. The remaining sources of this second type appear unresolved, and their properties are varied. We speculate on the similarity between the sources of the second type and those of the Orion population of radio sources.

Neutron Imaging at Compact Accelerator-Driven Neutron Sources in Japan

Directory of Open Access Journals (Sweden)

Yoshiaki Kiyanagi

2018-03-01

Full Text Available Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron sources and opened new application fields in neutron imaging. The world’s first dedicated imaging instrument at pulsed neutron sources was constructed at J-PARC in Japan owing to the development of such new methods. Then, usefulness of the compact accelerator-driven neutron sources in neutron science was recognized and such facilities were newly constructed in Japan. Now, existing and new sources have been used for neutron imaging. Traditional imaging and newly developed pulsed neutron imaging such as Bragg edge transmission have been applied to various fields by using compact and large neutron facilities. Here, compact accelerator-driven neutron sources used for imaging in Japan are introduced and some of their activities are presented.

Inverse compton light source: a compact design proposal

Energy Technology Data Exchange (ETDEWEB)

Deitrick, Kirsten Elizabeth [Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2017-05-01

In the last decade, there has been an increasing demand for a compact Inverse Compton Light Source (ICLS) which is capable of producing high-quality X-rays by colliding an electron beam and a high-quality laser. It is only in recent years when both SRF and laser technology have advanced enough that compact sources can approach the quality found at large installations such as the Advanced Photon Source at Argonne National Laboratory. Previously, X-ray sources were either high flux and brilliance at a large facility or many orders of magnitude lesser when produced by a bremsstrahlung source. A recent compact source was constructed by Lyncean Technologies using a storage ring to produce the electron beam used to scatter the incident laser beam. By instead using a linear accelerator system for the electron beam, a significant increase in X-ray beam quality is possible, though even subsequent designs also featuring a storage ring offer improvement. Preceding the linear accelerator with an SRF reentrant gun allows for an extremely small transverse emittance, increasing the brilliance of the resulting X-ray source. In order to achieve sufficiently small emittances, optimization was done regarding both the geometry of the gun and the initial electron bunch distribution produced off the cathode. Using double-spoke SRF cavities to comprise the linear accelerator allows for an electron beam of reasonable size to be focused at the interaction point, while preserving the low emittance that was generated by the gun. An aggressive final focusing section following the electron beam's exit from the accelerator produces the small spot size at the interaction point which results in an X-ray beam of high flux and brilliance. Taking all of these advancements together, a world class compact X-ray source has been designed. It is anticipated that this source would far outperform the conventional bremsstrahlung and many other compact ICLSs, while coming closer to performing at the

Compact radio sources

International Nuclear Information System (INIS)

Altschuler, D.R.

1975-01-01

Eighty-seven compact radio sources were monitored between 1971 and 1974 with the National Radio Astronomy Observatory interferometer. Both flux density and polarization were measured at intervals of about one month at wavelengths of 3.7 and 11.1 cms. Forty-four sources showed definite variability in their total and/or polarized flux density. The variations in polarization were of a shorter time scale than the corresponding flux density variations. Some of the qualitative features of an expanding source model were observed. The data suggest that some form of injection of relativistic electrons is taking place. The absence of significant depolarization in the variable sources indicates that only a small fraction of the mass of the radio outburst is in the form of non-relativistic plasma. Some of the objects observed belong to the BL-Lacertal class. It is shown that this class is very inhomogeneous in its radio properties. For the violently variable BL-Lacertal type objects the spectrum, flux variations and polarization data strongly suggest that these are very young objects

X-ray bursters and the X-ray sources of the galactic bulge

Science.gov (United States)

Lewin, W. H. G.; Joss, P. C.

An attempt is made to distill from observational and theoretical information on the galactic bulge X-ray sources in general, and on the X-ray burst sources in particular, those aspects which seem to have the greatest relevance to the understanding of these sources. Galactic bulge sources appear to be collapsed objects of roughly solar mass, in most cases neutron stars, which are accreting matter from low-mass stellar companions. Type I bursts seem to result from thermonuclear flashes in the surface layers of some of these neutron stars, while the type II bursts from the Rapid Burster are almost certainly due to an instability in the accretion flow onto a neutron star. It is concluded that the studies cited offer a new and powerful observational handle on the fundamental properties of neutron stars and of the interacting binary systems in which they are often contained.

Development of a compact powdery sample negative ion source

Energy Technology Data Exchange (ETDEWEB)

Wada, Motoi [Doshisha Univ., Tanabe, Kyoto (Japan). Faculty of Engineering; Sasao, Mamiko; Kawano, Hiroyuki

1997-02-01

A gas-feed-free compact negative ion source can be realized by utilizing the process of electron stimulated desorption from powdery sample. A negative ion source of this type is designed to be attached to a standard 1.33 inch copper-gasket-flange. The ion source is operated stable with LiH powder for more than 10 hours with the mass-separated negative hydrogen ion current of 1 nA. The source causes minute gas emission, and particularly suitable for ion beam applications in which a good vacuum is required. The present status of the compact ion source development is briefly described. (author)

Development of compact size penning ion source for compact neutron generator.

Science.gov (United States)

Das, Basanta Kumar; Shyam, Anurag

2008-12-01

For long-life operation, easy to mount and compact in size penning type ion sources are widely used in different fields of research such as neutron generators, material research, and surface etching. One penning type ion source has been developed in our laboratory. Applying high voltage of 2 kV between two oppositely biased electrodes and using permanent magnet of 500 gauss magnetic field along the axis, we had produced the glow discharge in the plasma region. The performance of this source was investigated using nitrogen gas. Deuterium ions were produced and extracted on the basis of chosen electrodes and the angle of extraction. Using a single aperture plasma electrode, the beam was extracted along the axial direction. The geometry of plasma electrode is an important factor for the efficient extraction of the ions from the plasma ion source. The extracted ion current depends upon the shape of the plasma meniscus. A concave shaped plasma meniscus produces converged ion beam. The convergence of extracted ions is related to the extraction electrode angle. The greater the angle, the more the beam converges. We had studied experimentally this effect with a compact size penning ion source. The detailed comparison among the different extraction geometry and different electrode angle are discussed in this paper.

X-ray spectral models of Galactic bulge sources - the emission-line factor

International Nuclear Information System (INIS)

Vrtilek, S.D.; Swank, J.H.; Kallman, T.R.

1988-01-01

Current difficulties in finding unique and physically meaningful models for the X-ray spectra of Galactic bulge sources are exacerbated by the presence of strong, variable emission and absorption features that are not resolved by the instruments observing them. Nine Einstein solid state spectrometer (SSS) observations of five Galactic bulge sources are presented for which relatively high resolution objective grating spectrometer (OGS) data have been published. It is found that in every case the goodness of fit of simple models to SSS data is greatly improved by adding line features identified in the OGS that cannot be resolved by the SSS but nevertheless strongly influence the spectra observed by SSS. 32 references

A compact reactor/ORC power source

International Nuclear Information System (INIS)

Meier, K.L.; Kirchner, W.L.; Willcutt, G.J.

1986-01-01

A compact power source that combines an organic Rankine cycle (ORC) electric generator with a nuclear reactor heat source is being designed and fabricated. Incorporating existing ORC technology with proven reactor technology, the compact reactor/ORC power source offers high reliability while minimizing the need for componenet development. Thermal power at 125 kWt is removed from the coated particle fueled, graphite moderated reactor by heat pipes operating at 500 0 C. Outside the reactor vessel and connected to the heat pipes are vaporizers in which the toluene ORC working fluid is heated to 370 0 C. In the turbine-alternator-pump (TAP) combined-rotating unit, the thermal energy of the toluene is converted to 25 kWe of electric power. Lumped parameter systems analyses combined with a finite element thermal analyses combined with a finite element thermal analysis have aided in the power source design. The analysis have provided assurance of reliable multiyear normal operation as well as full power operation with upset conditions, such as failed heat pipes and inoperative ORC vaporizers. Because of inherent high reliability, long life, and insensitivity to upset conditions, this power source is especially suited for use in remote, inaccessible locations where fuel delivery and maintenance costs are high

Report of the Basic Energy Sciences Workshop on Compact Light Sources

Energy Technology Data Exchange (ETDEWEB)

Barletta, William A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Borland, Michael [Argonne National Lab. (ANL), Argonne, IL (United States)

2010-05-11

This report is based on a BES Workshop on Compact Light Sources, held May 11-12, 2010, to evaluated the advantages and disadvantages of compact light source approaches and compared their performance to the third generation storage rings and free-electron lasers. The workshop examined the state of the technology for compact light sources and their expected progress. The workshop evaluated the cost efficiency, user access, availability, and reliability of such sources. Working groups evaluated the advantages and disadvantages of Compact Light Source (CLS) approaches, and compared their performance to the third-generation storage rings and free-electron lasers (FELs). The primary aspects of comparison were 1) cost effectiveness, 2) technical availability v. time frame, and 3) machine reliability and availability for user access. Five categories of potential sources were analyzed: 1) inverse Compton scattering (ICS) sources, 2) mini storage rings, 3) plasma sources, 4) sources using plasma-based accelerators, and 5) laser high harmonic generation (HHG) sources. Compact light sources are not a substitute for large synchrotron and FEL light sources that typically also incorporate extensive user support facilities. Rather they offer attractive, complementary capabilities at a small fraction of the cost and size of large national user facilities. In the far term they may offer the potential for a new paradigm of future national user facility. In the course of the workshop, we identified overarching R&D topics over the next five years that would enhance the performance potential of both compact and large-scale sources: Development of infrared (IR) laser systems delivering kW-class average power with femtosecond pulses at kHz repetition rates. These have application to ICS sources, plasma sources, and HHG sources. Development of laser storage cavities for storage of 10-mJ picosecond and femtosecond pulses focused to micron beam sizes. Development of high-brightness, high

OSO-7 observations of high galactic latitude x-ray sources

International Nuclear Information System (INIS)

Markert, T.H.; Canizares, C.R.; Clark, G.W.; Li, F.K.; Northridge, P.L.; Sprott, G.F.; Wargo, G.F.

1976-01-01

Six hundred days of observations by the MIT X-ray detectors aboard OSO-7 have been analyzed. All-sky maps of X-ray intensity have been constructed from these data. A sample map is displayed. Seven sources with galactic latitude vertical-barb/subi//subi/vertical-bar>10degree, discovered during the mapping process, are reported, and upper limits are set on other high-latitude sources. The OSO-7 results are compared with those of Uhuru and an implication of this comparison, that many of the high-latitude sources may be variable, is discussed

Optical observations of binary X-ray sources

International Nuclear Information System (INIS)

Charles, P.

1982-01-01

Here I shall consider only those systems where the compact object is a neutron star (or in a few cases perhaps a black hole). Since van Paradijs (1982) has recently produced an excellent and comprehensive review of optical observations of compact galactic X-ray sources I shall summarise the basic properties of the optical counterparts and discuss a few representative systems in some detail. (orig./WL)

DENSITY OF WARM IONIZED GAS NEAR THE GALACTIC CENTER: LOW RADIO FREQUENCY OBSERVATIONS

International Nuclear Information System (INIS)

Roy, Subhashis

2013-01-01

We have observed the Galactic center (GC) region at 0.154 and 0.255 GHz with the Giant Metrewave Radio Telescope. A total of 62 compact likely extragalactic (EG) sources are detected. Their scattering sizes decrease linearly with increasing angular distance from the GC up to about 1°. The apparent scattering sizes of the sources are more than an order of magnitude less than predicted earlier by the NE2001 model of Galactic electron distribution within 359.°5 e is ∼10 cm –3 , which matches the NE2001 model. This model predicts the EG sources to be resolved out from 1.4 GHz interferometric surveys. However, out of 10 EG sources expected in the region, 8 likely EG are present in the 1.4 GHz catalog. Ionized interfaces of dense molecular clouds to the ambient medium are most likely responsible for strong scattering and low radio frequency absorption. However, dense GC clouds traced by CS J = 1-0 emission are found to have a narrow distribution of ∼0.°2 across the Galactic plane. Angular distribution of most EG sources seen through the so-called Hyperstrong Scattering Region are random in b, and typically ∼7 out of 10 sources will not be seen through the dense molecular clouds, which explains why most of them are not scatter broadened at 1.4 GHz

Radio Wavelength Studies of the Galactic Center Source N3, Spectroscopic Instrumentation For Robotic Telescope Systems, and Developing Active Learning Activities for Astronomy Laboratory Courses

Science.gov (United States)

Ludovici, Dominic Alesio

2017-08-01

The mysterious radio source N3 appears to be located within the vicinity of the Radio Arc region of the Galactic Center. To investigate the nature of this source, we have conducted radio observations with the VLA and the VLBA. Continuum observations between 2 and 50 GHz reveal that N3 is an extremely compact and bright source with a non-thermal spectrum. Molecular line observations with the VLA reveal a compact molecular cloud adjacent to N3 in projection. The properties of this cloud are consistent with other galactic center clouds. We are able to rule out several hypotheses for the nature of N3, though a micro-blazar origin cannot be ruled out. Robotic Telescope systems are now seeing widespread deployment as both teaching and research instruments. While these systems have traditionally been able to produce high quality images, these systems have lacked the capability to conduct spectroscopic observations. To enable spectroscopic observations on the Iowa Robotic Observatory, we have developed a low cost (˜ 500), low resolution (R ˜ 300) spectrometer which mounts inside a modified filter wheel and a moderate cost (˜ 5000), medium resolution (R ˜ 8000) fiber-fed spectrometer. Software has been developed to operate both instruments robotically and calibration pipelines are being developed to automate calibration of the data. The University of Iowa offers several introductory astronomy laboratory courses taken by many hundreds of students each semester. To improve student learning in these laboratory courses, we have worked to integrate active learning into laboratory activities. We present the pedagogical approaches used to develop and update the laboratory activities and present an inventory of the current laboratory exercises. Using the inventory, we make observations of the strengths and weaknesses of the current exercises and provide suggestions for future refinement of the astronomy laboratory curriculum.

High-Energy Cosmic Ray Self-Confinement Close to Extra-Galactic Sources.

Science.gov (United States)

Blasi, Pasquale; Amato, Elena; D'Angelo, Marta

2015-09-18

The ultrahigh-energy cosmic rays observed on the Earth are most likely accelerated in extra-Galactic sources. For the typical luminosities invoked for such sources, the electric current associated to the flux of cosmic rays that leave them is large. The associated plasma instabilities create magnetic fluctuations that can efficiently scatter particles. We argue that this phenomenon forces cosmic rays to be self-confined in the source proximity for energies Esources for energies Esource luminosity in units of 10^{44} erg/s.

Galactic Bulge Giants: Probing Stellar and Galactic Evolution. 1. Catalogue of Spitzer IRAC and MIPS Sources (PREPRINT)

Science.gov (United States)

Uttenthaler, Stefan; Stute, Matthias; Sahai, Raghvendra; Blommaert, Joris A.; Schultheis, Mathias; Kraemer, Kathleen E.; Groenewegen, Martin A.; Price, Stephan D.

2010-01-01

Aims. We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus fundamental questions for late stellar evolution, such as the stage at which substantial mass-loss begins on the red giant branch and its dependence on fundamental stellar properties, remain unanswered. We aim at providing evidence and answers to these questions. Methods. To this end, we observed seven 15 15 arcmin2 fields in the nuclear bulge and its vicinity with unprecedented sensitivity using the IRAC and MIPS imaging instruments on-board the Spitzer Space Telescope. In each of the fields, tens of thousands of point sources were detected. Results. In the first paper based on this data set, we present the observations, data reduction, the final catalogue of sources, and a detailed comparison to previous mid-IR surveys of the Galactic bulge, as well as to theoretical isochrones. We find in general good agreement with other surveys and the isochrones, supporting the high quality of our catalogue.

A full-sky, high-resolution atlas of galactic 12 μm dust emission with WISE

International Nuclear Information System (INIS)

Meisner, Aaron M.; Finkbeiner, Douglas P.

2014-01-01

We describe our custom processing of the entire Wide-field Infrared Survey Explorer (WISE) 12 μm imaging data set, and present a high-resolution, full-sky map of diffuse Galactic dust emission that is free of compact sources and other contaminating artifacts. The principal distinctions between our resulting co-added images and the WISE Atlas stacks are our removal of compact sources, including their associated electronic and optical artifacts, and our preservation of spatial modes larger than 1.°5. We provide access to the resulting full-sky map via a set of 430 12.°5 × 12.°5 mosaics. These stacks have been smoothed to 15'' resolution and are accompanied by corresponding coverage maps, artifact images, and bit-masks for point sources, resolved compact sources, and other defects. When combined appropriately with other mid-infrared and far-infrared data sets, we expect our WISE 12 μm co-adds to form the basis for a full-sky dust extinction map with angular resolution several times better than Schlegel et al.

Compact synchrotron radiation source

International Nuclear Information System (INIS)

Liu, N.; Wang, T.; Tian, J.; Lin, Y.; Chen, S.; He, W.; Hu, Y.; Li, Q.

1985-01-01

A compact 800 MeV synchrotron radiation source is discussed. The storage ring has a circumference of 30.3 m, two 90 degree and four 45 degree bending magnet sections, two long straight sections and four short straight sections. The radius of the bending magnet is 2.224m. The critical wave length is 24A. The injector is a 15 Mev Microtron Electrons are accelerated from 15 Mev to 800 Mev by ramping the field of the ring. The expected stored current will be around 100 ma

XMM-NEWTON MEASUREMENT OF THE GALACTIC HALO X-RAY EMISSION USING A COMPACT SHADOWING CLOUD

International Nuclear Information System (INIS)

Henley, David B.; Shelton, Robin L.; Cumbee, Renata S.; Stancil, Phillip C.

2015-01-01

Observations of interstellar clouds that cast shadows in the soft X-ray background can be used to separate the background Galactic halo emission from the local emission due to solar wind charge exchange (SWCX) and/or the Local Bubble (LB). We present an XMM-Newton observation of a shadowing cloud, G225.60–66.40, that is sufficiently compact that the on- and off-shadow spectra can be extracted from a single field of view (unlike previous shadowing observations of the halo with CCD-resolution spectrometers, which consisted of separate on- and off-shadow pointings). We analyzed the spectra using a variety of foreground models: one representing LB emission, and two representing SWCX emission. We found that the resulting halo model parameters (temperature T h ≈ 2 × 10 6 K, emission measure E h ≈4×10 −3  cm −6  pc) were not sensitive to the foreground model used. This is likely due to the relative faintness of the foreground emission in this observation. However, the data do favor the existence of a foreground. The halo parameters derived from this observation are in good agreement with those from previous shadowing observations, and from an XMM-Newton survey of the Galactic halo emission. This supports the conclusion that the latter results are not subject to systematic errors, and can confidently be used to test models of the halo emission

Compact X-ray Light Source Workshop Report

Energy Technology Data Exchange (ETDEWEB)

Thevuthasan, Suntharampillai; Evans, James E.; Terminello, Louis J.; Koppenaal, David W.; Manke, Kristin L.; Plata, Charity

2012-12-01

This report, produced jointly by EMSL and FCSD, is the result of a workshop held in September 2011 that examined the utility of a compact x-ray light source (CXLS) in addressing many scientific challenges critical to advancing energy science and technology.

The 1.4-2.7 micron spectrum of the point source at the galactic center

Science.gov (United States)

Treffers, R. R.; Fink, U.; Larson, H. P.; Gautier, T. N., III

1976-01-01

The spectrum of the 2-micron point source at the galactic center is presented over the range from 1.4 to 2.7 microns. The two-level-transition CO band heads are seen near 2.3 microns, confirming that the radiation from this source is due to a cool supergiant star. The heliocentric radial velocity is found to be - 173 (+ or -90) km/s and is consistent with the star being in orbit about a dense galactic nucleus. No evidence is found for Brackett-gamma emission, and no interstellar absorption features are seen. Upper limits for the column densities of interstellar H2, CH4, CO, and NH3 are derived.

A compact, coherent light source system architecture

Science.gov (United States)

Biedron, S. G.; Dattoli, G.; DiPalma, E.; Einstein, J.; Milton, S. V.; Petrillo, V.; Rau, J. V.; Sabia, E.; Spassovsky, I. P.; van der Slot, P. J. M.

2016-09-01

Our team has been examining several architectures for short-wavelength, coherent light sources. We are presently exploring the use and role of advanced, high-peak power lasers for both accelerating the electrons and generating a compact light source with the same laser. Our overall goal is to devise light sources that are more accessible by industry and in smaller laboratory settings. Although we cannot and do not want to compete directly with sources such as third-generation light sources or that of national-laboratory-based free-electron lasers, we have several interesting schemes that could bring useful and more coherent, short-wavelength light source to more researchers. Here, we present and discuss several results of recent simulations and our future steps for such dissemination.

The Einstein objective grating spectrometer survey of galactic binary X-ray sources

Science.gov (United States)

Vrtilek, S. D.; Mcclintock, J. E.; Seward, F. D.; Kahn, S. M.; Wargelin, B. J.

1991-01-01

The results of observations of 22 bright Galactic X-ray point sources are presented, and the most reliable measurements to date of X-ray column densities to these sources are derived. The results are consistent with the idea that some of the objects have a component of column density intrinsic to the source in addition to an interstellar component. The K-edge absorption due to oxygen is clearly detected in 10 of the sources and the Fe L and Ne K edges are detected in a few. The spectra probably reflect emission originating in a collisionally excited region combined with emission from a photoionized region excited directly by the central source.

Radio Follow-up on All Unassociated Gamma-Ray Sources from the Third Fermi Large Area Telescope Source Catalog

Energy Technology Data Exchange (ETDEWEB)

Schinzel, Frank K. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Petrov, Leonid [Astrogeo Center, Falls Church, VA 22043 (United States); Taylor, Gregory B. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States); Edwards, Philip G., E-mail: fschinze@nrao.edu [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, 1710 NSW (Australia)

2017-04-01

The third Fermi Large Area Telescope γ -ray source catalog (3FGL) contains over 1000 objects for which there is no known counterpart at other wavelengths. The physical origin of the γ -ray emission from those objects is unknown. Such objects are commonly referred to as unassociated and mostly do not exhibit significant γ -ray flux variability. We performed a survey of all unassociated γ -ray sources found in 3FGL using the Australia Telescope Compact Array and Very Large Array in the range 4.0–10.0 GHz. We found 2097 radio candidates for association with γ -ray sources. The follow-up with very long baseline interferometry for a subset of those candidates yielded 142 new associations with active galactic nuclei that are γ -ray sources, provided alternative associations for seven objects, and improved positions for another 144 known associations to the milliarcsecond level of accuracy. In addition, for 245 unassociated γ -ray sources we did not find a single compact radio source above 2 mJy within 3 σ of their γ -ray localization. A significant fraction of these empty fields, 39%, are located away from the Galactic plane. We also found 36 extended radio sources that are candidates for association with a corresponding γ -ray object, 19 of which are most likely supernova remnants or H ii regions, whereas 17 could be radio galaxies.

Discovery of a Nonblazar Gamma-Ray Transient Source Near the Galactic Plane: GRO J1838-04

Science.gov (United States)

Tavani, M.; Oliversen, Ronald (Technical Monitor)

2001-01-01

We report the discovery of a remarkable gamma-ray transient source near the Galactic plane, GRO J1838-04. This source was serendipitously discovered by EGRET in 1995 June with a peak intensity of approx. (4 +/- 1) x 10(exp -6) photons/sq cm s (for photon energies larger than 100 MeV) and a 5.9 sigma significance. At that time, GRO J1838-04 was the second brightest gamma-ray source in the sky. A subsequent EGRET pointing in 1995 late September detected the source at a flux smaller than its peak value by a factor of approx. 7. We determine that no radio-loud spectrally flat blazar is within the error box of GRO J1838-04. We discuss the origin of the gamma-ray transient source and show that interpretations in terms of active galactic nuclei or isolated pulsars are highly problematic. GRO J1838-04 provides strong evidence for the existence of a new class of variable gamma-ray sources.

Identification of Hard X-ray Sources in Galactic Globular Clusters: Simbol-X Simulations

Science.gov (United States)

Servillat, M.

2009-05-01

Globular clusters harbour an excess of X-ray sources compared to the number of X-ray sources in the Galactic plane. It has been proposed that many of these X-ray sources are cataclysmic variables that have an intermediate magnetic field, i.e. intermediate polars, which remains to be confirmed and understood. We present here several methods to identify intermediate polars in globular clusters from multiwavelength analysis. First, we report on XMM-Newton, Chandra and HST observations of the very dense Galactic globular cluster NGC 2808. By comparing UV and X-ray properties of the cataclysmic variable candidates, the fraction of intermediate polars in this cluster can be estimated. We also present the optical spectra of two cataclysmic variables in the globular cluster M 22. The HeII (4868 Å) emission line in these spectra could be related to the presence of a magnetic field in these objects. Simulations of Simbol-X observations indicate that the angular resolution is sufficient to study X-ray sources in the core of close, less dense globular clusters, such as M 22. The sensitivity of Simbol-X in an extended energy band up to 80 keV will allow us to discriminate between hard X-ray sources (such as magnetic cataclysmic variables) and soft X-ray sources (such as chromospherically active binaries).

Small compact pulsed electron source for radiation technologies

International Nuclear Information System (INIS)

Korenev, Sergey

2002-01-01

The small compact pulsed electron source for radiation technologies is considered in the report. The electron source consists of pulsed high voltage Marx generator and vacuum diode with explosive emission cathode. The main parameters of electron source are next: kinetic energy is 100-150 keV, beam current is 5-200 A and pulse duration is 100-400 nsec. The distribution of absorbed doses in irradiated materials is considered. The physical feasibility of pulsed low energy electron beam for applications is considered

SECULAR EVOLUTION OF COMPACT BINARIES NEAR MASSIVE BLACK HOLES: GRAVITATIONAL WAVE SOURCES AND OTHER EXOTICA

International Nuclear Information System (INIS)

Antonini, Fabio; Perets, Hagai B.

2012-01-01

The environment near supermassive black holes (SMBHs) in galactic nuclei contains a large number of stars and compact objects. A fraction of these are likely to be members of binaries. Here we discuss the binary population of stellar black holes and neutron stars near SMBHs and focus on the secular evolution of such binaries, due to the perturbation by the SMBH. Binaries with highly inclined orbits with respect to their orbit around the SMBH are strongly affected by secular Kozai processes, which periodically change their eccentricities and inclinations (Kozai cycles). During periapsis approach, at the highest eccentricities during the Kozai cycles, gravitational wave (GW) emission becomes highly efficient. Some binaries in this environment can inspiral and coalesce at timescales much shorter than a Hubble time and much shorter than similar binaries that do not reside near an SMBH. The close environment of SMBHs could therefore serve as a catalyst for the inspiral and coalescence of binaries and strongly affect their orbital properties. Such compact binaries would be detectable as GW sources by the next generation of GW detectors (e.g., advanced-LIGO). Our analysis shows that ∼0.5% of such nuclear merging binaries will enter the LIGO observational window while on orbits that are still very eccentric (e ∼> 0.5). The efficient GW analysis for such systems would therefore require the use of eccentric templates. We also find that binaries very close to the SMBH could evolve through a complex dynamical (non-secular) evolution, leading to emission of several GW pulses during only a few years (though these are likely to be rare). Finally, we note that the formation of close stellar binaries, X-ray binaries, and their merger products could be induced by similar secular processes, combined with tidal friction rather than GW emission as in the case of compact object binaries.

Supermassive dark-matter Q-balls in galactic centers?

Energy Technology Data Exchange (ETDEWEB)

Troitsky, Sergey [Institute for Nuclear Research of the Russian Academy of Sciences,60th October Anniversary Prospect 7a, Moscow 117312 (Russian Federation); Moscow Institute for Physics and Technology,Institutskii per. 9, 141700, Dolgoprudny, Moscow Region (Russian Federation)

2016-11-11

Though widely accepted, it is not proven that supermassive compact objects (SMCOs) residing in galactic centers are black holes. In particular, the Milky Way’s SMCO can be a giant nontopological soliton, Q-ball, made of a scalar field: this fits perfectly all observational data. Similar but tiny Q-balls produced in the early Universe may constitute, partly or fully, the dark matter. This picture explains in a natural way, why our SMCO has very low accretion rate and why the observed angular size of the corresponding radio source is much smaller than expected. Interactions between dark-matter Q-balls may explain how SMCOs were seeded in galaxies and resolve well-known problems of standard (non-interacting) dark matter.

Compact wire array sources: power scaling and implosion physics.

Energy Technology Data Exchange (ETDEWEB)

Serrano, Jason Dimitri; Chuvatin, Alexander S. (Laboratoire du Centre National de la Recherche Scientifique Ecole Polytechnique, Palaiseau, France); Jones, M. C.; Vesey, Roger Alan; Waisman, Eduardo M.; Ivanov, V. V. (University of Nevada - Reno, Reno, NV); Esaulov, Andrey A. (University of Nevada - Reno, Reno, NV); Ampleford, David J.; Cuneo, Michael Edward; Kantsyrev, Victor Leonidovich (University of Nevada - Reno, Reno, NV); Coverdale, Christine Anne; Rudakov, L. I. (Icarus Research, Bethesda, MD); Jones, Brent Manley; Safronova, Alla S. (University of Nevada - Reno, Reno, NV); Vigil, Marcelino Patricio

2008-09-01

A series of ten shots were performed on the Saturn generator in short pulse mode in order to study planar and small-diameter cylindrical tungsten wire arrays at {approx}5 MA current levels and 50-60 ns implosion times as candidates for compact z-pinch radiation sources. A new vacuum hohlraum configuration has been proposed in which multiple z pinches are driven in parallel by a pulsed power generator. Each pinch resides in a separate return current cage, serving also as a primary hohlraum. A collection of such radiation sources surround a compact secondary hohlraum, which may potentially provide an attractive Planckian radiation source or house an inertial confinement fusion fuel capsule. Prior to studying this concept experimentally or numerically, advanced compact wire array loads must be developed and their scaling behavior understood. The 2008 Saturn planar array experiments extend the data set presented in Ref. [1], which studied planar arrays at {approx}3 MA, 100 ns in Saturn long pulse mode. Planar wire array power and yield scaling studies now include current levels directly applicable to multi-pinch experiments that could be performed on the 25 MA Z machine. A maximum total x-ray power of 15 TW (250 kJ in the main pulse, 330 kJ total yield) was observed with a 12-mm-wide planar array at 5.3 MA, 52 ns. The full data set indicates power scaling that is sub-quadratic with load current, while total and main pulse yields are closer to quadratic; these trends are similar to observations of compact cylindrical tungsten arrays on Z. We continue the investigation of energy coupling in these short pulse Saturn experiments using zero-dimensional-type implosion modeling and pinhole imaging, indicating 16 cm/?s implosion velocity in a 12-mm-wide array. The same phenomena of significant trailing mass and evidence for resistive heating are observed at 5 MA as at 3 MA. 17 kJ of Al K-shell radiation was obtained in one Al planar array fielded at 5.5 MA, 57 ns and we

Obscured flat spectrum radio active galactic nuclei as sources of high-energy neutrinos

NARCIS (Netherlands)

Maggi, G.; Buitink, S.; Correa, P.; de Vries, K. D.; Gentile, G.; Tavares, J. León; Scholten, O.; van Eijndhoven, N.; Vereecken, M.; Winchen, T.

2016-01-01

Active galactic nuclei (AGN) are believed to be one of the main source candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently discovered by the IceCube neutrino observatory. Nevertheless, several correlation studies between AGN and the cosmic neutrinos detected by IceCube show no

Determining the nature of faint X-ray sources from the ASCA Galactic center survey

Science.gov (United States)

Lutovinov, A. A.; Revnivtsev, M. G.; Karasev, D. I.; Shimansky, V. V.; Burenin, R. A.; Bikmaev, I. F.; Vorob'ev, V. S.; Tsygankov, S. S.; Pavlinsky, M. N.

2015-05-01

We present the results of the the identification of six objects from the ASCA Galactic center and Galactic plane surveys: AX J173548-3207, AX J173628-3141, AX J1739.5-2910, AX J1740.4-2856, AX J1740.5-2937, and AX J1743.9-2846. Chandra, XMM-Newton, and XRT/Swift X-ray data have been used to improve the positions of the optical counterparts to these sources. Thereafter, we have carried out a series of spectroscopic observations of the established optical counterparts at the RTT-150 telescope. Analysis of X-ray and optical spectra as well as photometric measurements in a wide wavelength range based on optical and infrared catalogs has allowed the nature of the program sources to be determined. Two X-ray objects have been detected in the error circle of AX J173628-3141: one is a coronally active G star and the other may be a symbiotic star, a red giant with an accreting white dwarf. Three sources (AX J1739.5-2910, AX J1740.5-2937, AX J1743.9-2846) have turned out to be active G-K stars, presumably RS CVn objects, one (AX J1740.4-2856) is an M dwarf, and another one (AX J173548-3207) most likely a low-mass X-ray binary in its low state. The distances and corresponding luminosities of the sources in the soft X-ray band (0.5-10 keV) have been estimated; analysis of deep INTEGRAL Galactic center observations has not revealed a statistically significant flux at energies >20 keV from any of them.

TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry. II. Additional sources

Science.gov (United States)

Müller, C.; Kadler, M.; Ojha, R.; Schulz, R.; Trüstedt, J.; Edwards, P. G.; Ros, E.; Carpenter, B.; Angioni, R.; Blanchard, J.; Böck, M.; Burd, P. R.; Dörr, M.; Dutka, M. S.; Eberl, T.; Gulyaev, S.; Hase, H.; Horiuchi, S.; Katz, U.; Krauß, F.; Lovell, J. E. J.; Natusch, T.; Nesci, R.; Phillips, C.; Plötz, C.; Pursimo, T.; Quick, J. F. H.; Stevens, J.; Thompson, D. J.; Tingay, S. J.; Tzioumis, A. K.; Weston, S.; Wilms, J.; Zensus, J. A.

2018-02-01

Context. TANAMI is a multiwavelength program monitoring active galactic nuclei (AGN) south of - 30° declination including high-resolution very long baseline interferometry (VLBI) imaging, radio, optical/UV, X-ray, and γ-ray studies. We have previously published first-epoch8.4 GHz VLBI images of the parsec-scale structure of the initial sample. In this paper, we present images of 39 additional sources. The full sample comprises most of the radio- and γ-ray brightest AGN in the southern quarter of the sky, overlapping with the region from which high-energy (> 100 TeV) neutrino events have been found. Aims: We characterize the parsec-scale radio properties of the jets and compare them with the quasi-simultaneous Fermi/LAT γ-ray data. Furthermore, we study the jet properties of sources which are in positional coincidence with high-energy neutrino events compared to the full sample. We test the positional agreement of high-energy neutrino events with various AGN samples. Methods: TANAMI VLBI observations at 8.4 GHz are made with southern hemisphere radio telescopes located in Australia, Antarctica, Chile, New Zealand, and South Africa. Results: Our observations yield the first images of many jets below - 30° declination at milliarcsecond resolution. We find that γ-ray loud TANAMI sources tend to be more compact on parsec-scales and have higher core brightness temperatures than γ-ray faint jets, indicating higher Doppler factors. No significant structural difference is found between sources in positional coincidence with high-energy neutrino events and other TANAMI jets. The 22 γ-ray brightest AGN in the TANAMI sky show only a weak positional agreement with high-energy neutrinos demonstrating that the > 100 TeV IceCube signal is not simply dominated by a small number of the γ-ray brightest blazars. Instead, a larger number of sources have to contribute to the signal with each individual source having only a small Poisson probability for producing an event in

Hard X-ray emission mechanism of active galactic nuclei sources

International Nuclear Information System (INIS)

Liang, E.P.T.

1979-01-01

Within the framework of unsaturated Compton disk accretion onto a supermassive black hole as model for power-law active galactic nuclei X-ray sources (as opposed to the synchro-Compton model), we compare the hot inner disk model of Shapiro, Lightman, and Eardley and the disk corona model with balanced conduction and Compton losses. Both can generate electron temperatures > or approx. =10 9 K in the supermassive case but promise other observable distinctions. The sandwich configuration of the disk corona provides a natural explanation of why Comptonization is unsaturated

NEW CONSTRAINTS ON THE GALACTIC HALO MAGNETIC FIELD USING ROTATION MEASURES OF EXTRAGALACTIC SOURCES TOWARD THE OUTER GALAXY

International Nuclear Information System (INIS)

Mao, S. A.; McClure-Griffiths, N. M.; Gaensler, B. M.; Brown, J. C.; Van Eck, C. L.; Stil, J. M.; Taylor, A. R.; Haverkorn, M.; Kronberg, P. P.; Shukurov, A.

2012-01-01

We present a study of the Milky Way disk and halo magnetic field, determined from observations of Faraday rotation measure (RM) toward 641 polarized extragalactic radio sources in the Galactic longitude range 100°-117°, within 30° of the Galactic plane. For |b| –2 and –62 ± 5 rad m –2 in the northern and southern Galactic hemispheres, respectively. If the RM distribution is a signature of the large-scale field parallel to the Galactic plane, then this suggests that the halo magnetic field toward the outer Galaxy does not reverse direction across the mid-plane. The variation of RM as a function of Galactic latitude in this longitude range is such that RMs become more negative at larger |b|. This is consistent with an azimuthal magnetic field of strength 2 μG (7 μG) at a height 0.8-2 kpc above (below) the Galactic plane between the local and the Perseus spiral arm. We propose that the Milky Way could possess spiral-like halo magnetic fields similar to those observed in M51.

Design of the compact ECR ion source for heavy-ion therapy

International Nuclear Information System (INIS)

Muramatsu, M.; Kitagawa, A.; Sato, S.; Sato, Y.; Yamada, S.; Hattori, T.; Shibuya, S.

1999-01-01

Heavy ion cancer treatment is successfully being done at the Heavy Ion Medical Accelerator in Chiba (HIMAC). Design philosophy for the ion sources for medical facilities are as follows: sufficient beam intensity, a few hundred eμA; long lifetime with good stability; easy operation and easy maintenance; and compactness. In order to develop such source for future heavy-ion facilities, we have tested compact electron cyclotron resonance (ECR) ion sources using permanent magnets both for axial and radial confinement of hot electrons. Since the yield of C 2+ ion in the firstly-developed source (2.45 GHz ECR) was 15 eμA and far below the medical requirement (-150 eμA for the HIMAC), a new source has been proposed, having the frequency of 10 GHz. The extracted intensity of C 4+ (and C 2+ ) ions is expected to be higher than 200 eμA. (author)

Search for Extended Sources in the Galactic Plane Using Six Years of Fermi -Large Area Telescope Pass 8 Data above 10 GeV

International Nuclear Information System (INIS)

Ackermann, M.; Buehler, R.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Caragiulo, M.; Bloom, E. D.; Bottacini, E.; Cameron, R. A.; Bonino, R.; Brandt, T. J.; Castro, D.; Bregeon, J.; Bruel, P.; Caraveo, P. A.; Cavazzuti, E.

2017-01-01

The spatial extension of a γ -ray source is an essential ingredient to determine its spectral properties, as well as its potential multiwavelength counterpart. The capability to spatially resolve γ -ray sources is greatly improved by the newly delivered Fermi -Large Area Telescope (LAT) Pass 8 event-level analysis, which provides a greater acceptance and an improved point-spread function, two crucial factors for the detection of extended sources. Here, we present a complete search for extended sources located within 7° from the Galactic plane, using 6 yr of Fermi -LAT data above 10 GeV. We find 46 extended sources and provide their morphological and spectral characteristics. This constitutes the first catalog of hard Fermi -LAT extended sources, named the Fermi Galactic Extended Source Catalog, which allows a thorough study of the properties of the Galactic plane in the sub-TeV domain.

Search for Extended Sources in the Galactic Plane Using Six Years of Fermi -Large Area Telescope Pass 8 Data above 10 GeV

Energy Technology Data Exchange (ETDEWEB)

Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d’Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bissaldi, E.; Caragiulo, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); Bloom, E. D.; Bottacini, E.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Bonino, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino (Italy); Brandt, T. J.; Castro, D. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier (France); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133 Milano (Italy); Cavazzuti, E., E-mail: jcohen@astro.umd.edu, E-mail: elizabeth.a.hays@nasa.gov [Agenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma (Italy); and others

2017-07-10

The spatial extension of a γ -ray source is an essential ingredient to determine its spectral properties, as well as its potential multiwavelength counterpart. The capability to spatially resolve γ -ray sources is greatly improved by the newly delivered Fermi -Large Area Telescope (LAT) Pass 8 event-level analysis, which provides a greater acceptance and an improved point-spread function, two crucial factors for the detection of extended sources. Here, we present a complete search for extended sources located within 7° from the Galactic plane, using 6 yr of Fermi -LAT data above 10 GeV. We find 46 extended sources and provide their morphological and spectral characteristics. This constitutes the first catalog of hard Fermi -LAT extended sources, named the Fermi Galactic Extended Source Catalog, which allows a thorough study of the properties of the Galactic plane in the sub-TeV domain.

Study of the spectral characteristics of unidentified galactic EGRET sources. Are they pulsar-like?

Science.gov (United States)

Merck, M.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Fichtel, C. E.; Fierro, J. M.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mayer-Hasselwander, H. A.; Michelson, P. F.; von Montigny, C.; Muecke, A.; Mukherjee, R.; Nolan, P. L.; Pohl, M.; Schneid, E.; Sreekumar, P.; Thompson, D. J.; Willis, T. D.

1996-12-01

A spectral study of unidentified galactic EGRET sources was performed. The derived spectra are compared to the spectra of pulsars to test the hypothesis, that a significant fraction of these sources are Geminga like radio-quiet pulsars (Yadigaroglu & Romani 1995ApJ...449..211Y). Most of the sources show significantly different spectra than expected under this hypothesis. Of those with spectra consistent with typical pulsar spectra, four are positionally consistent with young spin-powered radio pulsars leaving only very few Geminga type candidates in the sample.

Monitoring the Galactic Centre with the Australia Telescope Compact Array

Czech Academy of Sciences Publication Activity Database

Borkar, A.; Eckart, A.; Straubmeier, C.; Kunneriath, Devaky; Jalali, B.; Sabha, N.; Shahzamanian, B.; García-Marín, M.; Valencia-S, M.; Sjouwerman, L.; Britzen, S.; Karas, Vladimír; Dovčiak, Michal; Donea, A.; Zensus, A.

2016-01-01

Roč. 458, č. 3 (2016), s. 2336-2349 ISSN 0035-8711 R&D Projects: GA ČR(CZ) GC13-00070J Institutional support: RVO:67985815 Keywords : galactic Centre * black hole Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.961, year: 2016

Mono-energy coronary angiography with a compact light source

Science.gov (United States)

Eggl, Elena; Mechlem, Korbinian; Braig, Eva; Kulpe, Stephanie; Dierolf, Martin; Günther, Benedikt; Achterhold, Klaus; Herzen, Julia; Gleich, Bernhard; Rummeny, Ernst; Noël, Peter B.; Pfeiffer, Franz; Muenzel, Daniela

2017-03-01

While conventional x-ray tube sources reliably provide high-power x-ray beams for everyday clinical practice, the broad spectra that are inherent to these sources compromise the diagnostic image quality. For a monochromatic x-ray source on the other hand, the x-ray energy can be adjusted to optimal conditions with respect to contrast and dose. However, large-scale synchrotron sources impose high spatial and financial demands, making them unsuitable for clinical practice. During the last decades, research has brought up compact synchrotron sources based on inverse Compton scattering, which deliver a highly brilliant, quasi-monochromatic, tunable x-ray beam, yet fitting into a standard laboratory. One application that could benefit from the invention of these sources in clinical practice is coronary angiography. Being an important and frequently applied diagnostic tool, a high number of complications in angiography, such as renal failure, allergic reaction, or hyperthyroidism, are caused by the large amount of iodine-based contrast agent that is required for achieving sufficient image contrast. Here we demonstrate monochromatic angiography of a porcine heart acquired at the MuCLS, the first compact synchrotron source. By means of a simulation, the CNR in a coronary angiography image achieved with the quasi-mono-energetic MuCLS spectrum is analyzed and compared to a conventional x-ray-tube spectrum. The results imply that the improved CNR achieved with a quasi-monochromatic spectrum can allow for a significant reduction of iodine contrast material.

Compact FEL-driven inverse compton scattering gamma-ray source

Energy Technology Data Exchange (ETDEWEB)

Placidi, M. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Di Mitri, S., E-mail: simone.dimitri@elettra.eu [Elettra - Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste (Italy); Pellegrini, C. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); University of California, Los Angeles, CA 90095 (United States); Penn, G. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2017-05-21

Many research and applications areas require photon sources capable of producing gamma-ray beams in the multi-MeV energy range with reasonably high fluxes and compact footprints. Besides industrial, nuclear physics and security applications, a considerable interest comes from the possibility to assess the state of conservation of cultural assets like statues, columns etc., via visualization and analysis techniques using high energy photon beams. Computed Tomography scans, widely adopted in medicine at lower photon energies, presently provide high quality three-dimensional imaging in industry and museums. We explore the feasibility of a compact source of quasi-monochromatic, multi-MeV gamma-rays based on Inverse Compton Scattering (ICS) from a high intensity ultra-violet (UV) beam generated in a free-electron laser by the electron beam itself. This scheme introduces a stronger relationship between the energy of the scattered photons and that of the electron beam, resulting in a device much more compact than a classic ICS for a given scattered energy. The same electron beam is used to produce gamma-rays in the 10–20 MeV range and UV radiation in the 10–15 eV range, in a ~4×22 m{sup 2} footprint system.

Active Galactic Nuclei: Sources for ultra high energy cosmic rays?

Energy Technology Data Exchange (ETDEWEB)

Biermann, Peter L. [MPI for Radioastronomy, Bonn (Germany); Dept. of Phys. and Astron., Univ. of Bonn (Germany); Dept. of Phys. and Astr., Univ. of Alabama, Tuscaloosa, AL (United States); Dept. of Phys., Univ. of Alabama at Huntsville, AL (United States); Inst. Nucl. Phys. FZ, Karlsruhe Inst. of Techn. (KIT) (Germany); Becker, Julia K. [Institution foer Fysik, Goeteborgs Univ. (Sweden); Dept. of Phys., Univ. Dortmund, Dortmund (Germany); Caramete, Laurentiu [MPI for Radioastronomy, Bonn (Germany); Institute for Space Studies, Bucharest (Romania); Curutiu, Alex [MPI for Radioastronomy, Bonn (Germany); Engel, Ralph [Inst. Nucl. Phys. FZ, Karlsruhe Inst. of Techn. (KIT) (Germany); Falcke, Heino [Dept. of Astrophys., IMAP, Radboud Univ., Nijmegen (Netherlands); ASTRON, Dwingeloo (Netherlands); Gergely, Laszlo A. [Dept. Appl. Sci., London South Bank University (United Kingdom); Dept. of Theoret. and Exp. Phys., Univ. of Szeged, Szeged (Hungary); Isar, P. Gina [Inst. Nucl. Phys. FZ, Karlsruhe Inst. of Techn. (KIT) (Germany); Institute for Space Studies, Bucharest (Romania); Maris, Ioana C. [Inst. Nucl. Phys. FZ, Karlsruhe Inst. of Techn. (KIT) (Germany); Meli, Athina [Physik. Inst. Univ. Erlangen-Nuernberg (Germany); Kampert, Karl-Heinz [Phys. Dept., Univ. Wuppertal (Germany); Stanev, Todor [Bartol Research Inst., Univ. of Delaware, Newark, DE (United States); Tascau, Oana [Phys. Dept., Univ. Wuppertal (Germany); Zier, Christian [MPI for Radioastronomy, Bonn (Germany); Raman Res. Inst., Bangalore (India)

2009-05-15

The origin of ultra high energy cosmic rays promises to lead us to a deeper understanding of the structure of matter. This is possible through the study of particle collisions at center-of-mass energies in interactions far larger than anything possible with the Large Hadron Collider, albeit at the substantial cost of no control over the sources and interaction sites. For the extreme energies we have to identify and understand the sources first, before trying to use them as physics laboratories. Here we describe the current stage of this exploration. The most promising contenders as sources are radio galaxies and gamma ray bursts. The sky distribution of observed events yields a hint favoring radio galaxies. Key in this quest are the intergalactic and galactic magnetic fields, whose strength and structure are not yet fully understood. Current data and statistics do not yet allow a final judgement. We outline how we may progress in the near future.

Active Galactic Nuclei: Sources for ultra high energy cosmic rays?

International Nuclear Information System (INIS)

Biermann, Peter L.; Becker, Julia K.; Caramete, Laurentiu; Curutiu, Alex; Engel, Ralph; Falcke, Heino; Gergely, Laszlo A.; Isar, P. Gina; Maris, Ioana C.; Meli, Athina; Kampert, Karl-Heinz; Stanev, Todor; Tascau, Oana; Zier, Christian

2009-01-01

The origin of ultra high energy cosmic rays promises to lead us to a deeper understanding of the structure of matter. This is possible through the study of particle collisions at center-of-mass energies in interactions far larger than anything possible with the Large Hadron Collider, albeit at the substantial cost of no control over the sources and interaction sites. For the extreme energies we have to identify and understand the sources first, before trying to use them as physics laboratories. Here we describe the current stage of this exploration. The most promising contenders as sources are radio galaxies and gamma ray bursts. The sky distribution of observed events yields a hint favoring radio galaxies. Key in this quest are the intergalactic and galactic magnetic fields, whose strength and structure are not yet fully understood. Current data and statistics do not yet allow a final judgement. We outline how we may progress in the near future.

Study with the sigma data base of the galactic bulge hard x-ray and gamma-ray sources

International Nuclear Information System (INIS)

Vargas, Marielle

1997-01-01

The Sigma coded-mask telescope on board the Granat spacecraft produces sky images in the hard X-ray and soft gamma-ray energy domain (30-1300 keV) with an angular resolution of 15 arc minutes. The observations of the 18 Angstroms x 17 Angstroms region around the Galactic Center, performed with Sigma regularly during seven years, allowed the detection of a cluster of 17 sources showing activity beyond 40 ke V. This cluster is identified with the Galactic Bulge and its core coincides with the Galactic Center. Each of these sources reveals matter accretion by a collapse star in binary system. Its nature is determined by the luminosity and the spectral behavior recorded beyond 40 keV. Three accreting black holes show peculiar transient activities and comparable flare luminosities providing a criterion to evaluate distance of other specimens located elsewhere in the Galaxy. No sign of activity has been detected from the very center of the Galaxy where a supermassive black hole would be placed and would accrete the surrounding matter. (author) [fr

Many faces of compact objects: distance, optical extinction and multi-wavelength behaviour

International Nuclear Information System (INIS)

Corbel, Stephane

1999-01-01

This thesis is devoted to a multi-wavelength study of accretion-ejection phenomena around compact stars (black holes and neutron stars). The first part of this manuscript describes problems related to the determination of the distance and the optical extinction to compact objects - fundamental parameters for the evaluation of the energy budget of these systems. To this end, the structure and the dynamics of the Galaxy are studied by observations of the atomic and molecular gas along the line of sight to compact stars. This method leads to the first evaluation of the distance to two Soft Gamma Repeaters: SGR 1806-20 and SGR 1627-41. We then draw some conclusions on the nature of these sources of recurrent gamma-ray bursts. The above method is then applied to two X-ray binaries: Cir X-1 and GX 339-4. In the second part of this thesis, we present a multi-wavelength study of the Galactic black hole candidate GX 339-4. We first discuss the characteristics of the radio emission from GX 339-4. In 1998, GX 339-4 underwent a transition to a soft-high X-ray state and observations in three wavelength regimes (radio, soft and hard X-rays) revealed new patterns of behaviour. This allowed us to constrain the region of origin of the radio emission (a compact jet) in GX 339-4 and allowed a better understanding of the physical coupling between accretion and ejection in GX 339-4. An analogy with the black hole candidate Cyg X-1 is then presented. Finally, these results are discussed in the context of micro-quasars and active galactic nuclei in order to gain a deeper insight into the accretion-ejection coupling around compact objects. (author) [fr

Positrons annihilation and the Galactic center

International Nuclear Information System (INIS)

Wallyn, Pierre

1992-01-01

The Galactic center has been observed in gamma rays, many times since more than two decades and we do not still have a full comprehensive picture of this region. It is fairly well established that the 511 keV annihilation line has two origins: a steady diffuse emission, which follows more or less the type I supernovae distribution along the Galactic plane and a variable emission coming from the positrons emitted by (at least) one compact object and annihilating in a nearby cold molecular cloud. We present here an analysis of the profiles and intensifies of the 511 keV annihilation line observed in the direction of the Galactic center. We find that a warm medium (temperature of 8000 K) can describe the annihilation of positrons from the diffuse component of the line. The high state observations of the 511 keV line can be explained if the time-variable component is coming from the annihilation of the positrons in a cold medium (temperature around 80 K). This constraint on the annihilation medium temperature supports the association with the molecular cloud G-0.86-0.08 in the direction of 1E1740.7-2942. On may 22, 1989, HEXAGONE detected a narrow 511 keV line and also a broad emission around 170 keV in the direction of the Galactic center. Two weeks before, EXITE observed in the same direction a new transient source EXS 1737.9-2952 which showed a bump around 102 keV. We propose a simple semi-quantitative model which can mimic the bumps as well as its time variations and emphasize the strong similarities between EXS1737.9-2952 and Nova Muscae. We study the behaviour of positron annihilation by charge exchange in the cold phase of the interstellar medium. We calculate formula for the slowing-down time before thermalization of positrons of a given initial energy, for different medium densities. Our scenario explains the lack of detection of the recombination lines from positronium and gives new constraints on their possible observation. (author) [fr

NuSTAR and XMM-Newton observations of 1e1743.1-2843: indications of a neutron star LMXB nature of the compact object

DEFF Research Database (Denmark)

Lotti, Simone; Natalucci, Lorenzo; Mori, Kaya

2016-01-01

We report on the results of NuSTAR and XMM-Newton observations of the persistent X-ray source 1E1743.1-2843, located in the Galactic Center region. The source was observed between 2012 September and October by NuSTAR and XMM-Newton, providing almost simultaneous observations in the hard and soft X......-ray bands. The high X-ray luminosity points to the presence of an accreting compact object. We analyze the possibilities of this accreting compact object being either a neutron star (NS) or a black hole, and conclude that the joint XMM-Newton and NuSTAR spectrum from 0.3 to 40 keV fits a blackbody spectrum...

First results from the INTEGRAL galactic plane scans

DEFF Research Database (Denmark)

Winkler, C.; Gehrels, N.; Schonfelder, V.

2003-01-01

Scans of the Galactic plane performed at regular intervals constitute a key element of the guaranteed time observations of the INTEGRAL observing programme. These scans are done for two reasons: frequent monitoring of the Galactic plane in order to detect transient sources, and time resolved mapp...... mapping of the Galactic plane in continuum and diffuse line emission. This paper describes first results obtained from the Galactic plane scans executed so far during the early phase (Dec. 2002-May 2003) of the nominal mission.......Scans of the Galactic plane performed at regular intervals constitute a key element of the guaranteed time observations of the INTEGRAL observing programme. These scans are done for two reasons: frequent monitoring of the Galactic plane in order to detect transient sources, and time resolved...

Observation of Galactic Sources of Very High Energy γ-RAYS with the Magic Telescope

Science.gov (United States)

Bartko, H.

The MAGIC telescope with its 17m diameter mirror is today the largest operating single-dish Imaging Air Cherenkov Telescope (IACT). It is located on the Canary Island La Palma, at an altitude of 2200 m above sea level, as part of the Roque de los Muchachos European Northern Observatory. The MAGIC telescope detects celestial very high energy γ-radiation in the energy band between about 50 GeV and 10 TeV. Since the autumn of 2004 MAGIC has been taking data routinely, observing various objects, like supernova remnants (SNRs), γ-ray binaries, Pulsars, Active Galactic Nuclei (AGN) and Gamma-ray Bursts (GRB). We briefly describe the observational strategy, the procedure implemented for the data analysis, and discuss the results of observations of Galactic Sources.

400 kV injector compact ECR ion source

International Nuclear Information System (INIS)

Constantin, F.; Catana, D.; Macovei, M.; Ivanov, E.

1997-01-01

Obtaining multiple ionised ions is a fundamental problem for some applications and research. Multiple ionised ions can be produced from electronic bombardment, when n·τ≥5·10 9 cm -3 · s, where n is the density of electrons (in cm -3 ) and τ is the time of interaction between electrons and ions . The relative speed of electrons and ions determines the equilibrium between the stripping process of the atom's electrons and their capture. An ion source with high ionisation efficiency and large output current is the ECR source (Electron Cyclotron Resonance). Using an ECR source with permanent magnets as ion source for the injector will lead to following advantages: - the possibility to obtain multiple ionised particles; - an increase of ion beam intensities; - the expanding of accelerator activities; - a longer working time, due to magnetron lifetime. The ECR ion source is robust, compact and capable of high intensities of extracted ion current. The large functional domain for the residual gas pressure allows the production of multiple charged ions. The source can be easily integrated in the TRILAC's injection structure. We realised a compact microwave ion source which has an axial magnetic field generated by a permanent magnet of Co-Sm. 1200 G magnetic field is greater than the 875 G magnetic field corresponding to the electron-cyclotron frequency of 2.45 GHz. The microwave generator is a magnetron (2.45 GHz and 200 W in continuos wave). The microwave is fed through a coaxial connector on the top of flange. The test was made on He gas at a pressure between 8· 10 -4 and 5·10 -2 torr. The ion beam current was measured vs. extracted potential from 3 kV to 10 kV and has a dependence according to U 3/2 law. A maximal ion current of 300 μA at 10 kV extraction potential was measured. Dimension of ECR ion source, including Einzel lens are φ=12 cm and h=16 cm. (authors)

A systematic search for dwarf counterparts to ultra compact high velocity clouds

Science.gov (United States)

Bennet, Paul; Sand, David J.; Crnojevic, Denija; Strader, Jay

2015-01-01

Observations of the Universe on scales smaller than typical, massive galaxies challenge the standard Lambda Cold Dark Matter paradigm for structure formation. It is thus imperative to discover and characterize the faintest dwarf galaxy systems, not just within the Local Group, but in relatively isolated environments as well in order to properly connect them with models of structure formation. Here we report on a systematic search of public ultraviolet and optical archives for dwarf galaxy counterparts to so-called Ultra Compact High Velocity Clouds (UCHVCs), which are compact, isolated HI sources recently found in the Galactic Arecibo L-band Feed Array-HI (GALFA-HI) and Arecibo Legacy Fast ALFA (ALFALFA-HI) surveys. Our search has uncovered at least three strong dwarf galaxy candidates, and we present their inferred star formation rate and structural properties here.

A compact time-of-flight mass spectrometer for ion source characterization

International Nuclear Information System (INIS)

Chen, L.; Wan, X.; Jin, D. Z.; Tan, X. H.; Huang, Z. X.; Tan, G. B.

2015-01-01

A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters

VERITAS Galactic Observations

Energy Technology Data Exchange (ETDEWEB)

Hughes, Gareth

2013-06-15

We report on recent Galactic results and discoveries made by the VERITAS collaboration. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is a ground-based gamma-ray observatory, located in southern Arizona, able to detect gamma rays of energies from 100 GeV up to 30 TeV. VERITAS has been fully operational since 2007 and its current sensitivity enables the detection of a 1% Crab Nebula flux at 5 sigma in under 30 hours. The observatory is well placed to view large parts of the galactic plane including its center, resulting in a strong galactic program. Objects routinely observed include Pulsars, Pulsar Wind Nebula, X-ray binaries and sources with unidentified counterparts in other wavelengths.

New Evidence for a Black Hole in the Compact Binary Cygnus X-3

Science.gov (United States)

Shrader, Chris R.; Titarchuk, Lev; Shaposhnikov, Nikolai

2010-01-01

The bright and highly variable X-ray and radio source known as Cygnus X-3 was among the first X-ray sources discovered, yet it remains in many ways an enigma. Its known to consist of a massive. Wolf-Rayet primary in an extremely tight orbit with a compact object. Yet one of the most basic of pa.ranietern the mass of the compact object - is not known. Nor is it even clear whether its is a neutron star or a black hole. In this Paper we present our analysis of the broad-band high-energy continua covering a substantial range in luminosity and spectral morphology. We apply these results to a recently identified scaling relationship which has been demonstrated to provide reliable estimates of the compact object mass in a number of accretion powered binaries. This analysis leads us to conclude that the compact object in Cygnus X-3 has a mass greater than 4.2 solar mass thus clearly indicative of a black hole and as such resolving a longstanding issue. The full range of uncertainty in our analysis and from using a. range of recently published distance estimates constrains the compact object mass to lie between 4.2 solar mass and 14.4 solar mass. Our favored estimate, based on a 9.0 kpc distance estimate is approx. l0 solar mass, with the. error margin of 3.2 solar masses. This result may thus pose challenges to shared-envelope evolutionary models of compact binaries. as well as establishing Cygnus X-3 as the first confirmed accretion-powered galactic gamma: ray source.

Magnetic field structures in active compact radio sources

International Nuclear Information System (INIS)

Jones, T.W.; Rudnick, L.; Fiedler, R.L.; Aller, H.D.; Aller, M.F.; Hodge, P.E.

1985-01-01

The analysis of simultaneous multifrequency linear polarimetry data between 1.4 GHz and 90 GHz for about 20 active, compact radio sources at six epochs from 1977 December 10 1980 July is presented. In addition, monthly 8 Ghz polarization data on the same sources were examined. The general polarization characteristics of these sources can be well described in terms of magnetic fields which are largely turbulent and slightly anisotropic. The magnetic field symmetry axes are generally aligned with the source structural axes on the milli-arcsecond scale (OJ 287 is a notable exception.) Monte Carlo calculations indicate that observed polarization variations and in particular rotator polarization events can be produced in this model as a consequence of random walks generated through evolution of the turbulent magnetic field. 43 references

Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries

Directory of Open Access Journals (Sweden)

Luc Blanchet

2014-02-01

Full Text Available To be observed and analyzed by the network of gravitational wave detectors on ground (LIGO, VIRGO, etc. and by the future detectors in space (eLISA, etc., inspiralling compact binaries -- binary star systems composed of neutron stars and/or black holes in their late stage of evolution -- require high-accuracy templates predicted by general relativity theory. The gravitational waves emitted by these very relativistic systems can be accurately modelled using a high-order post-Newtonian gravitational wave generation formalism. In this article, we present the current state of the art on post-Newtonian methods as applied to the dynamics and gravitational radiation of general matter sources (including the radiation reaction back onto the source and inspiralling compact binaries. We describe the post-Newtonian equations of motion of compact binaries and the associated Lagrangian and Hamiltonian formalisms, paying attention to the self-field regularizations at work in the calculations. Several notions of innermost circular orbits are discussed. We estimate the accuracy of the post-Newtonian approximation and make a comparison with numerical computations of the gravitational self-force for compact binaries in the small mass ratio limit. The gravitational waveform and energy flux are obtained to high post-Newtonian order and the binary's orbital phase evolution is deduced from an energy balance argument. Some landmark results are given in the case of eccentric compact binaries -- moving on quasi-elliptical orbits with non-negligible eccentricity. The spins of the two black holes play an important role in the definition of the gravitational wave templates. We investigate their imprint on the equations of motion and gravitational wave phasing up to high post-Newtonian order (restricting to spin-orbit effects which are linear in spins, and analyze the post-Newtonian spin precession equations as well as the induced precession of the orbital plane.

Models of mass segregation at the Galactic Centre

International Nuclear Information System (INIS)

Freitag, Marc; Amaro-Seoane, Pau; Kalogera, Vassiliki

2006-01-01

We study the process of mass segregation through 2-body relaxation in galactic nuclei with a central massive black hole (MBH). This study has bearing on a variety of astrophysical questions, from the distribution of X-ray binaries at the Galactic centre, to tidal disruptions of main- sequence and giant stars, to inspirals of compact objects into the MBH, an important category of events for the future space borne gravitational wave interferometer LISA. In relatively small galactic nuclei, typical hosts of MBHs with masses in the range 10 4 - 10 7 M o-dot , the relaxation induces the formation of a steep density cusp around the MBH and strong mass segregation. Using a spherical stellar dynamical Monte-Carlo code, we simulate the long-term relaxational evolution of galactic nucleus models with a spectrum of stellar masses. Our focus is the concentration of stellar black holes to the immediate vicinity of the MBH. Special attention is given to models developed to match the conditions in the Milky Way nucleus

A Compact Source of Flash-Corona Discharge for Biomedical Applications

Science.gov (United States)

Moshkunov, S. I.; Khomich, V. Yu.; Shershunova, E. A.

2018-01-01

A compact source of low-temperature plasma for biological and medical applications is proposed, which operates at kilohertz frequencies in the regime of flash-corona discharge with an energy of 0.1 mJ/pulse. The plasma source was tested in application to plasma pretreatment of green salad seeds. Plasma-treated seeds exhibited increased (by about 25%) germination speed as compared to that in the untreated control.

Changing-Look AGNs or Short-Lived Radio Sources?

Energy Technology Data Exchange (ETDEWEB)

Wołowska, Aleksandra [Toruń Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń (Poland); Kunert-Bajraszewska, Magdalena; Mooley, Kunal [Centre for Astrophysical Surveys, University of Oxford, Oxford (United Kingdom); Hallinan, Gregg, E-mail: ola@astro.umk.pl [Cahill Center for Astronomy, California Institute of Technology, Pasadena, CA (United States)

2017-11-17

The evolution of extragalactic radio sources has been a fundamental problem in the study of active galactic nuclei for many years. A standard evolutionary model has been created based on observations of a wide range of radio sources. In the general scenario of the evolution, the younger and smaller Gigahertz-Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) sources become large-scale FRI and FRII objects. However, a growing number of observations of low power radio sources suggests that the model cannot explain all their properties and there are still some aspects of the evolutionary path that remain unclear. There are indications, that some sources may be short-lived objects on timescales of 10{sup 4}–10{sup 5} years. Those objects represent a new population of active galaxies. Here, we present the discovery of several radio transient sources on timescales of 5–20 yrs, largely associated with renewed AGN (Active Galactic Nucleus) activity. These changing-look AGNs possibly represent behavior typical for many active galaxies.

DEVELOPMENT OF THE MODEL OF GALACTIC INTERSTELLAR EMISSION FOR STANDARD POINT-SOURCE ANALYSIS OF FERMI LARGE AREA TELESCOPE DATA

Energy Technology Data Exchange (ETDEWEB)

Acero, F.; Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d’Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States); Albert, A.; Baldini, L.; Bloom, E. D.; Bottacini, E.; Caliandro, G. A.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bissaldi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); Bonino, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino (Italy); Brandt, T. J.; Buson, S. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, Montpellier (France); Bruel, P., E-mail: isabelle.grenier@cea.fr, E-mail: casandjian@cea.fr [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, Palaiseau (France); and others

2016-04-01

Most of the celestial γ rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM), which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20° and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within ∼4° of the Galactic Center.

Compact neutron generator with nanotube ion source

Science.gov (United States)

Chepurnov, A. S.; Ionidi, V. Y.; Ivashchuk, O. O.; Kirsanov, M. A.; Kitsyuk, E. P.; Klenin, A. A.; Kubankin, A. S.; Nazhmudinov, R. M.; Nikulin, I. S.; Oleinik, A. N.; Pavlov, A. A.; Shchagin, A. V.; Zhukova, P. N.

2018-02-01

In this letter, we report the observation of fast neutrons generated when a positive acceleration potential is applied to an array of orientated carbon nanotubes, which are used as an ion source. The neutrons with energy of 2.45 MeV are generated as a result of D-D fusion reaction. The dependencies of the neutron yield on the value of the applied potential and residual pressure of deuterium are measured. The proposed approach is planned to be used for the development of compact neutron generators.

MILAGRO OBSERVATIONS OF MULTI-TeV EMISSION FROM GALACTIC SOURCES IN THE FERMI BRIGHT SOURCE LIST

International Nuclear Information System (INIS)

Abdo, A. A.; Linnemann, J. T.; Allen, B. T.; Chen, C.; Aune, T.; Berley, D.; Goodman, J. A.; Christopher, G. E.; Kolterman, B. E.; Mincer, A. I.; Nemethy, P.; DeYoung, T.; Dingus, B. L.; Hoffman, C. M.; Ellsworth, R. W.; Gonzalez, M. M.; Hays, E.; McEnery, J. E.; Huentemeyer, P. H.; Morgan, T.

2009-01-01

We present the result of a search of the Milagro sky map for spatial correlations with sources from a subset of the recent Fermi Bright Source List (BSL). The BSL consists of the 205 most significant sources detected above 100 MeV by the Fermi Large Area Telescope. We select sources based on their categorization in the BSL, taking all confirmed or possible Galactic sources in the field of view of Milagro. Of the 34 Fermi sources selected, 14 are observed by Milagro at a significance of 3 standard deviations or more. We conduct this search with a new analysis which employs newly optimized gamma-hadron separation and utilizes the full eight-year Milagro data set. Milagro is sensitive to gamma rays with energy from 1 to 100 TeV with a peak sensitivity from 10 to 50 TeV depending on the source spectrum and declination. These results extend the observation of these sources far above the Fermi energy band. With the new analysis and additional data, multi-TeV emission is definitively observed associated with the Fermi pulsar, J2229.0+6114, in the Boomerang pulsar wind nebula (PWN). Furthermore, an extended region of multi-TeV emission is associated with the Fermi pulsar, J0634.0+1745, the Geminga pulsar.

Compact Integrated DBR Laser Source for Absorption Lidar Instruments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to demonstrate a compact integrated laser module that addresses the requirements of the laser source in a water vapor differential absorption lidar (DIAL)...

On the nature of the galactic 2CG γ-ray sources

International Nuclear Information System (INIS)

Buccheri, R.; Morini, M.; Sacco, B.

1981-01-01

The identification of two γ-ray sources of the COS-B catalogue with radio pulsars is used as an important hint for the identification of the rest of the population. The relevant distributions of γ-ray pulsars visible at the Sun within the limiting sensitivity of COS-B are derived on the following assumptions: (i) the γ-ray luminosity is a decreasing power law of the pulsar age, as indicated by current models; (ii) the scale height of pulsars at creation is equal to that of the supernova remnants; (iii) the pulsars' birth rate and spatial distribution are those published by Taylor and Manchester (1977). As a preliminary result it is shown that 10 to 20 γ-ray pulsars may be visible from the Earth with distributional parameters not distinguishable from those of the 2CG γ-ray sources. It is suggested therefore that a significant fraction of the unidentified galactic γ-ray sources are pulsars. (author)

The DARPA compact Superconducting X-Ray Lithography Source features

International Nuclear Information System (INIS)

Heese, R.; Kalsi, S.; Leung, E.

1991-01-01

Under DARPA sponsorship, a compact Superconducting X-Ray Lithography Source (SXLS) is being designed and built by the Brookhaven National Laboratory (BNL) with industry participation from Grumman Corporation and General Dynamics. This source is optimized for lithography work for sub-micron high density computer chips, and is about the size of a billiard table (1.5 m x 4.0 m). The machine has a racetrack configuration with two 180 degree bending magnets being designed and built by General Dynamics under a subcontract with Grumman Corporation. The machine will have 18 photon ports which would deliver light peaked at a wave length of 10 Angstroms. Grumman is commercializing the SXLS device and plans to book orders for delivery of industrialized SXLS (ISXLS) versions in 1995. This paper will describe the major features of this device. The commercial machine will be equipped with a fully automated user-friendly control systems, major features of which are already working on a compact warm dipole ring at BNL. This ring has normal dipole magnets with dimensions identical to the SXLS device, and has been successfully commissioned

Beam dynamics design of an SP-FEL compact THz source

International Nuclear Information System (INIS)

Dai Dongdong; Dai Zhimin

2010-01-01

In recent years, people are looking for a new compact THz source with high emission power, one potential choice is to build small accelerator with Smith-Purcell radiation. The main difficulty is how to obtain high quality electron beam. In this paper, the beam dynamics design of a compact THz source is presented. The electron beam is produced by an electron gun and compressed by permanent magnets. The electron gun is similar to the Shanghai EBIT, but permanent magnets are used, instead of the superconducting magnets in Shanghai EBIT. With this design, we can reduce the size and cost of the whole device. Poisson/Pandira was employed to simulate and optimize the magnetic field. Egun was used to simulate the beam trajectories from the electron gun to the collector. Within 2 centimeters around the center of longitudinal magnetic field, the calculation showed that the beam satisfies to our design aim. (authors)

Evidence for Infrared-faint Radio Sources as z > 1 Radio-loud Active Galactic Nuclei

Science.gov (United States)

Huynh, Minh T.; Norris, Ray P.; Siana, Brian; Middelberg, Enno

2010-02-01

Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6-70 μm) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the spectral energy distribution of these objects shows that they are consistent with high-redshift (z >~ 1) active galactic nuclei.

The distances of the Galactic Novae

Science.gov (United States)

Ozdonmez, Aykut; Guver, Tolga; Cabrera-Lavers, Antonio; Ak, Tansel

2016-07-01

Using location of the RC stars on the CMDs obtained from the UKIDSS, VISTA and 2MASS photometry, we have derived the reddening-distance relations towards each Galactic nova for which at least one independent reddening measurement exists. We were able to determine the distances of 72 Galactic novae and set lower limits on the distances of 45 systems. The reddening curves of the systems are presented. These curves can be also used to estimate reddening or the distance of any source, whose location is close to the position of the nova in our sample. The distance measurement method in our study can be easily applicable to any source, especially for ones that concentrated along the Galactic plane.

Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries

Directory of Open Access Journals (Sweden)

Blanchet Luc

2006-06-01

Full Text Available The article reviews the current status of a theoretical approach to the problem of the emission of gravitational waves by isolated systems in the context of general relativity. Part A of the article deals with general post-Newtonian sources. The exterior field of the source is investigated by means of a combination of analytic post-Minkowskian and multipolar approximations. The physical observables in the far-zone of the source are described by a specific set of radiative multipole moments. By matching the exterior solution to the metric of the post-Newtonian source in the near-zone we obtain the explicit expressions of the source multipole moments. The relationships between the radiative and source moments involve many non-linear multipole interactions, among them those associated with the tails (and tails-of-tails of gravitational waves. Part B of the article is devoted to the application to compact binary systems. We present the equations of binary motion, and the associated Lagrangian and Hamiltonian, at the third post-Newtonian (3PN order beyond the Newtonian acceleration. The gravitational-wave energy flux, taking consistently into account the relativistic corrections in the binary moments as well as the various tail effects, is derived through 3.5PN order with respect to the quadrupole formalism. The binary's orbital phase, whose prior knowledge is crucial for searching and analyzing the signals from inspiralling compact binaries, is deduced from an energy balance argument.

Scintillating confusion: Evaluation of a technique for measuring compact structure in weak radio sources

International Nuclear Information System (INIS)

Spangler, S.R.; Cordes, J.M.; Meyers, K.A.

1979-01-01

An attractive scheme for investigating compact structure in weak radio sources is to study the scintillation properties of confusion in a large single-dish radio telescope. We have investigated the utility of this technique by observing the scintillations of 860-MHz confusion of the NRAO 300' (91 m) telescope. Analysis of these data indicated a reduction in the mean scintillation index with decreasing flux density which implied that weaker sources possessed less compact structure. More direct observations indicated that the weak sources of interest were not significantly deficient in compact structure, so the first result is probably due to properties of the IPS process in the strong scintillation regime. Our results may be due to overresolution (by the IPS process in the strong scintillation regime) of the ''hot spots'' responsible for scintillation in most strong sources at frequencies below 1000 MHz, or may indicate abnormally strong turbulence in the solar wind during August, 1977. Future applications of this method would be best conducted at lower frequencies with larger reflectors or short-spacing interferometers

The galactic contribution to IceCube's astrophysical neutrino flux

Energy Technology Data Exchange (ETDEWEB)

Denton, Peter B. [Niels Bohr International Academy, University of Copenhagen, The Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen (Denmark); Marfatia, Danny [Department of Physics and Astronomy, University of Hawaii at Manoa, 2505 Correa Rd., Honolulu, HI 96822 (United States); Weiler, Thomas J., E-mail: peterbd1@gmail.com, E-mail: dmarf8@hawaii.edu, E-mail: tom.weiler@vanderbilt.edu [Department of Physics and Astronomy, Vanderbilt University, 2301 Vanderbilt Place, Nashville, TN 37235 (United States)

2017-08-01

High energy neutrinos have been detected by IceCube, but their origin remains a mystery. Determining the sources of this flux is a crucial first step towards multi-messenger studies. In this work we systematically compare two classes of sources with the data: galactic and extragalactic. We assume that the neutrino sources are distributed according to a class of Galactic models. We build a likelihood function on an event by event basis including energy, event topology, absorption, and direction information. We present the probability that each high energy event with deposited energy E {sub dep}>60 TeV in the HESE sample is Galactic, extragalactic, or background. For Galactic models considered the Galactic fraction of the astrophysical flux has a best fit value of 1.3% and is <9.5% at 90% CL. A zero Galactic flux is allowed at <1σ.

X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

Directory of Open Access Journals (Sweden)

Kumiko Morihana

2014-12-01

Full Text Available We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE. We extracted 2,002 X-ray point sources in the Chandra Bulge Field (l =0°.113, b = 1°.424 down to ~10-14.8 ergscm-2s-1 in 2-8 keV band with the longest observation (900 ks of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard, B (soft and broad spectrum, and C (soft and peaked spectrum. In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

NEAR- AND FAR-FIELD RESPONSE TO COMPACT ACOUSTIC SOURCES IN STRATIFIED CONVECTION ZONES

International Nuclear Information System (INIS)

Cally, Paul S.

2013-01-01

The role of the acoustic continuum associated with compact sources in the Sun's interior wave field is explored for a simple polytropic model. The continuum produces a near-field acoustic structure—the so-called acoustic jacket—that cannot be represented by a superposition of discrete normal modes. Particular attention is paid to monochromatic point sources of various frequency and depth, and to the surface velocity power that results, both in the discrete f- and p-mode spectrum and in the continuum. It is shown that a major effect of the continuum is to heal the surface wave field produced by compact sources, and therefore to hide them from view. It is found that the continuous spectrum is not a significant contributor to observable inter-ridge seismic power.

A SCALING RELATION BETWEEN MEGAMASER DISK RADIUS AND BLACK HOLE MASS IN ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

Wardle, Mark; Yusef-Zadeh, Farhad

2012-01-01

Several thin, Keplerian, sub-parsec megamaser disks have been discovered in the nuclei of active galaxies and used to precisely determine the mass of their host black holes. We show that there is an empirical linear correlation between the disk radius and the black hole mass. We demonstrate that such disks are naturally formed by the partial capture of molecular clouds passing through the galactic nucleus and temporarily engulfing the central supermassive black hole. Imperfect cancellation of the angular momenta of the cloud material colliding after passing on opposite sides of the hole leads to the formation of a compact disk. The radial extent of the disk is determined by the efficiency of this process and the Bondi-Hoyle capture radius of the black hole, and naturally produces the empirical linear correlation of the radial extent of the maser distribution with black hole mass. The disk has sufficient column density to allow X-ray irradiation from the central source to generate physical and chemical conditions conducive to the formation of 22 GHz H 2 O masers. For initial cloud column densities ∼ 23.5 cm –2 the disk is non-self-gravitating, consistent with the ordered kinematics of the edge-on megamaser disks; for higher cloud columns the disk would fragment and produce a compact stellar disk similar to that observed around Sgr A* at the galactic center.

The TRIUMF compact DC H-/D- ion source

International Nuclear Information System (INIS)

Jayamanna, K.; McDonald, M.; Yuan, D.H.; Schmor, P.W.

1990-06-01

A compact dc H - /D - ion source using multicusp magnetic plasma confinement, has been experimentally studied and optimized on the TRIUMF ion source test stand. The plasma parameters have been obtained with rapid computer controlled Langmuir probe scans. The extraction electrode configuration, originally tailored to the TR30 cyclotron requirements, has been further developed. With a 12 mm diameter extraction hole this source now provides 9 mA within a normalized emittance of 0.44 π mm-mrad and can be easily modified for lower currents of smaller emittance (1 mA H - current with normalized emittance 0.12π.mm-mrad or 7 mA H - current with normalized emittance 0.34π.mm-mrad). The source has proven to have low maintenance, high reliability and long filament lifetime. This paper emphasizes basic plasma parameters which determine the efficiency of H - /D - production. Some experimental results obtained from several versions of the extraction system are also described. (Author) 6 refs., 8 figs

AN X-RAY COOLING-CORE CLUSTER SURROUNDING A LOW-POWER COMPACT STEEP SPECTRUM RADIO SOURCE 1321+045

International Nuclear Information System (INIS)

Kunert-Bajraszewska, M.; Siemiginowska, A.; Labiano, A.

2013-01-01

We discovered an X-ray cluster in a Chandra observation of the compact steep spectrum (CSS) radio source 1321+045 (z = 0.263). CSS sources are thought to be young radio objects at the beginning of their evolution and can potentially test the cluster heating process. 1321+045 is a relatively low-luminosity source and its morphology consists of two radio lobes on the opposite sides of a radio core with no evidence for jets or hotspots. The optical emission line ratios are consistent with an interstellar medium dominated by active galactic nucleus photoionization with a small contribution from star formation, and no contributions from shocks. Based on these ratios, we classify 1321+045 as a low excitation galaxy (LEG) and suggest that its radioactivity is in a coasting phase. The X-ray emission associated with the radio source is detected with 36.1 ± 8.3 counts, but the origin of this emission is highly uncertain. The current X-ray image of the cluster does not show any signatures of a radio source impact on the cluster medium. Chandra detects the cluster emission at >3σ level out to ∼60'' (240 kpc). We obtain the best-fit beta model parameters of the surface brightness profile of β = 0.58 ± 0.2 and a core radius of 9.4 +1.1 -0.9 arcsec. The average temperature of the cluster is equal to kT = 4.4 +0.5 -0.3 keV, with a temperature and cooling profile indicative of a cooling core. We measure the cluster luminosity L (0.5-2 k eV) = 3 × 10 44 erg s –1 and mass 1.5 × 10 14 M ☉

AN X-RAY COOLING-CORE CLUSTER SURROUNDING A LOW-POWER COMPACT STEEP SPECTRUM RADIO SOURCE 1321+045

Energy Technology Data Exchange (ETDEWEB)

Kunert-Bajraszewska, M. [Torun Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, NCU, Grudziacka 5, 87-100 Torun (Poland); Siemiginowska, A. [Harvard Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Labiano, A., E-mail: magda@astro.uni.torun.pl [Centro de Astrobiologia (CSIC-INTA), Carretera de Ajalvir km. 4, E-28850 Torrejon de Ardoz, Madrid (Spain)

2013-07-20

We discovered an X-ray cluster in a Chandra observation of the compact steep spectrum (CSS) radio source 1321+045 (z = 0.263). CSS sources are thought to be young radio objects at the beginning of their evolution and can potentially test the cluster heating process. 1321+045 is a relatively low-luminosity source and its morphology consists of two radio lobes on the opposite sides of a radio core with no evidence for jets or hotspots. The optical emission line ratios are consistent with an interstellar medium dominated by active galactic nucleus photoionization with a small contribution from star formation, and no contributions from shocks. Based on these ratios, we classify 1321+045 as a low excitation galaxy (LEG) and suggest that its radioactivity is in a coasting phase. The X-ray emission associated with the radio source is detected with 36.1 {+-} 8.3 counts, but the origin of this emission is highly uncertain. The current X-ray image of the cluster does not show any signatures of a radio source impact on the cluster medium. Chandra detects the cluster emission at >3{sigma} level out to {approx}60'' (240 kpc). We obtain the best-fit beta model parameters of the surface brightness profile of {beta} = 0.58 {+-} 0.2 and a core radius of 9.4{sup +1.1}{sub -0.9} arcsec. The average temperature of the cluster is equal to kT = 4.4{sup +0.5}{sub -0.3} keV, with a temperature and cooling profile indicative of a cooling core. We measure the cluster luminosity L{sub (0.5-2{sub keV)}} = 3 Multiplication-Sign 10{sup 44} erg s{sup -1} and mass 1.5 Multiplication-Sign 10{sup 14} M{sub Sun}.

The H.E.S.S. Galactic plane survey

Science.gov (United States)

H. E. S. S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bonnefoy, S.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carrigan, S.; Caroff, S.; Carosi, A.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Colafrancesco, S.; Condon, B.; Conrad, J.; Davids, I. D.; Decock, J.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'C.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Emery, G.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Gaté, F.; Giavitto, G.; Giebels, B.; Glawion, D.; Glicenstein, J. F.; Gottschall, D.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holch, T. L.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Malyshev, D.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poireau, V.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Rauth, R.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rinchiuso, L.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Safi-Harb, S.; Sahakian, V.; Saito, S.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schandri, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Shiningayamwe, K.; Simoni, R.; Sol, H.; Spanier, F.; Spir-Jacob, M.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steppa, C.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsirou, M.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Zorn, J.; Żywucka, N.

2018-04-01

We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) γ-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE γ-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of quality-selected data, covering the Galactic plane at longitudes from ℓ = 250° to 65° and latitudes |b|≤ 3°. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08° ≈ 5 arcmin mean point spread function 68% containment radius), sensitivity (≲1.5% Crab flux for point-like sources), and energy range (0.2-100 TeV). We constructed a catalog of VHE γ-ray sources from the HGPS data set with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the Galactic center region. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible

Automated detection of extended sources in radio maps: progress from the SCORPIO survey

Science.gov (United States)

Riggi, S.; Ingallinera, A.; Leto, P.; Cavallaro, F.; Bufano, F.; Schillirò, F.; Trigilio, C.; Umana, G.; Buemi, C. S.; Norris, R. P.

2016-08-01

Automated source extraction and parametrization represents a crucial challenge for the next-generation radio interferometer surveys, such as those performed with the Square Kilometre Array (SKA) and its precursors. In this paper, we present a new algorithm, called CAESAR (Compact And Extended Source Automated Recognition), to detect and parametrize extended sources in radio interferometric maps. It is based on a pre-filtering stage, allowing image denoising, compact source suppression and enhancement of diffuse emission, followed by an adaptive superpixel clustering stage for final source segmentation. A parametrization stage provides source flux information and a wide range of morphology estimators for post-processing analysis. We developed CAESAR in a modular software library, also including different methods for local background estimation and image filtering, along with alternative algorithms for both compact and diffuse source extraction. The method was applied to real radio continuum data collected at the Australian Telescope Compact Array (ATCA) within the SCORPIO project, a pathfinder of the Evolutionary Map of the Universe (EMU) survey at the Australian Square Kilometre Array Pathfinder (ASKAP). The source reconstruction capabilities were studied over different test fields in the presence of compact sources, imaging artefacts and diffuse emission from the Galactic plane and compared with existing algorithms. When compared to a human-driven analysis, the designed algorithm was found capable of detecting known target sources and regions of diffuse emission, outperforming alternative approaches over the considered fields.

NEAR- AND FAR-FIELD RESPONSE TO COMPACT ACOUSTIC SOURCES IN STRATIFIED CONVECTION ZONES

Energy Technology Data Exchange (ETDEWEB)

Cally, Paul S., E-mail: paul.cally@monash.edu [Monash Centre for Astrophysics and School of Mathematical Sciences, Monash University, Clayton, Victoria 3800 (Australia)

2013-05-01

The role of the acoustic continuum associated with compact sources in the Sun's interior wave field is explored for a simple polytropic model. The continuum produces a near-field acoustic structure-the so-called acoustic jacket-that cannot be represented by a superposition of discrete normal modes. Particular attention is paid to monochromatic point sources of various frequency and depth, and to the surface velocity power that results, both in the discrete f- and p-mode spectrum and in the continuum. It is shown that a major effect of the continuum is to heal the surface wave field produced by compact sources, and therefore to hide them from view. It is found that the continuous spectrum is not a significant contributor to observable inter-ridge seismic power.

Compact continuum radio sources in the Orion Nebula

International Nuclear Information System (INIS)

Garay, G.; Moran, J.M.; Reid, M.J.; European Southern Observatory, Garching, West Germany)

1987-01-01

The Orion Nebula was observed with the VLA in order to search for radio emission from compact H II regions indicative of embedded OB stars or from winds associated with pre-main sequence, low-mass stars. Fourteen of the 21 detected radio sources are within 30 arcsec of Omega 1 Orionis C; 13 of these objects are probably neutral condensations surrounded by ionized envelopes that are excited by the star. If the temperature of the ionized envelopes is 10,000 K and their electron densities decrease as the square of the distance from the core center, then a typical neutral condensation has a radius of 10 to the 15th cm and a peak electron density of 400,000/cu cm. Seven sources are in or near the Orion molecular cloud. Four of the sources have optical counterparts. Two are highly variable radio sources associated with X-ray sources, and two have radio spectra indicative of thermal emission. Two of the three optically invisible sources have radio emission likely to arise in a dense ionized envelope surrounding and excited by an early B-type star. 46 references

Development of 2.45GHz compact ECR ion sources with permanent magnets

International Nuclear Information System (INIS)

Tojyo, E.; Ohshiro, Y.; Oyaizu, M.; Shirakabe, Y.

1993-05-01

Two kinds of new compact ECR ion sources have been developed by use of permanent magnets only, for the purpose of acceleration tests of the 25.5MHz INS split coaxial RFQ linac and the 50MHz one. Confined magnetic fields of sources are constructed by permanent magnets only. In this paper design parameters, structures, magnetic field distributions and extracted beam properties of these sources are described briefly. (author)

A compact hard X-ray source for medical imaging and biomolecular studies

International Nuclear Information System (INIS)

Cline, D.B.; Green, M.A.; Kolonko, J.

1995-01-01

There are a large number of synchrotron light sources in the world. However, these sources are designed for physics, chemistry, and engineering studies. To our knowledge, none have been optimized for either medical imaging or biomolecular studies. There are special needs for these applications. We present here a preliminary design of a very compact source, small enough for a hospital or a biomolecular laboratory, that is suitable for these applications. (orig.)

HI Clouds Near the Galactic Center: Possible Tracers of the Nuclear Wind

Science.gov (United States)

Lockman, Felix J.; McClure-Griffiths, Naomi; DiTeodoro, Enrico

2017-01-01

We have used the Green Bank Telescope to discover more than one hundred neutral hydrogen clouds that appear to be embedded in the Fermi Bubble -- the Milky Way’s nuclear wind. With the other members of this population that were previously found with the Australia Telescope Compact Array, we now have a sample of about 200 such clouds. They are identified by their peculiar velocities. The cloud kinematics show no trace of Galactic rotation or association with the Galactic bar. Near longitude zero the clouds can have values of VLSR = +-200 km/s. No clouds have been detected with |VLSR| > 350 km/s. The clouds are concentrated toward the Galactic plane, but some are still found to |b|=10 degrees, or z > 1 kpc at the Galactic Center, where the current surveys end. These clouds are important tracers of conditions in the nuclear wind of the Milky Way.

Far infrared observations of the galactic center

International Nuclear Information System (INIS)

Gatley, I.

1977-01-01

Maps of a region 10' in diameter around the galactic center made simultaneously in three wavelength bands at 30 μm, 50 μm, and 100 μm with approximately 1' resolution are presented, and the distribution of far infrared luminosity and color temperature across this region is derived. The position of highest far infrared surface brightness coincides with the peak of the late-type stellar distribution and with the H II region Sgr A West. The high spatial and temperature resolution of the data is used to identify features of the far infrared maps with known sources of near infrared, radio continuum, and molecular emission. The emission mechanism and energy sources for the far infrared radiation are anslyzed qualitatively, and it is concluded that all of the observed far infrared radiation from the galactic center region can be attributed to thermal emission from dust heated both by the late-type stars and by the ultraviolet sources which ionize the H II regions. A self-consistent model for the far infrared emission from the galactic center region is presented. It is found that the visual extinction across the central 10 pc of the galaxy is only about 3 magnitudes, and that the dust density is fairly uniform in this region. An upper limit of 10 7 L/sub mass/ is set on the luminosity of any presently unidentified source of 0.1 to 1 μm radiation at the galactic center. Additional maps in the vicinity of the source Sgr B2 and observations of Sgr C bring the total number of H II regions within 1 0 of the galactic center studied by the present experiment to nine. The far infrared luminosity, color temperature and optical depth of these regions and the ratio of infrared flux to radio continuum flux lie in the range characteristic of spiral arm H II regions. The far infrared results are therefore consistent with the data that the galactic center H II regions are ionized by luminous, early type stars

Planck early results. XIII. Statistical properties of extragalactic radio sources in the Planck Early Release Compact Source Catalogue

DEFF Research Database (Denmark)

Lähteenmäki, A.; Poutanen, T.; Natoli, P.

2011-01-01

The data reported in Planck's Early Release Compact Source Catalogue (ERCSC) are exploited to measure the number counts (dN/dS) of extragalactic radio sources at 30, 44, 70, 100, 143 and 217 GHz. Due to the full-sky nature of the catalogue, this measurement extends to the rarest and brightest sou...

Hot-spots of radio sources in clusters of galaxies

International Nuclear Information System (INIS)

Saikia, D.J.

1979-01-01

A sample of extragalactic double radio sources is examined to test for a correlation between the prominence of compact hot-spots located at their outer edges and membership of clusters of galaxies. To minimize the effects of incompleteness in published catalogues of clusters, cluster classification is based on the number of galaxies in the neighbourhood of each source. After eliminating possible selection effects, it is found that sources in regions of high galactic density tend to have less prominent hot-spots. It is argued that the result is consistent with the 'continuous-flow' models of radio sources, but poses problems for the gravitational slingshot model. (author)

The Chandra Dust-scattering Halo of Galactic Center Transient Swift J174540.7–290015

Energy Technology Data Exchange (ETDEWEB)

Corrales, L. R. [Einstein Fellow, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI, 53706 (United States); Mon, B.; Haggard, D. [McGill Space Institute, McGill University, 3550 University Street, Montreal, QC, H3A 2A7 (Canada); Baganoff, F. K. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA, 02139 (United States); Garmire, G. [Huntingdon Institute for X-ray Astronomy, 10677 Franks Road Huntingdon, PA, 16652 (United States); Degenaar, N. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Reynolds, M. [University of Michigan, 1085 S. University, 311 West Hall, Ann Arbor, MI 48109 (United States)

2017-04-20

We report the detection of a dust-scattering halo around a recently discovered X-ray transient, Swift J174540.7–290015, which in early 2016 February underwent one of the brightest outbursts ( F {sub X} ≈ 5 × 10{sup −10} erg cm{sup −2} s{sup −1}) observed from a compact object in the Galactic Center field. We analyze four Chandra images that were taken as follow-up observations to Swift discoveries of new Galactic Center transients. After adjusting our spectral extraction for the effects of detector pile-up, we construct a point-spread function for each observation and compare it to the GC field before the outburst. We find residual surface brightness around Swift J174540.7–290015, which has a shape and temporal evolution consistent with the behavior expected from X-rays scattered by foreground dust. We examine the spectral properties of the source, which shows evidence that the object transitioned from a soft to hard spectral state as it faded below L {sub X} ∼ 10{sup 36} erg s{sup −1}. This behavior is consistent with the hypothesis that the object is a low-mass X-ray binary in the Galactic Center.

Model-independent requirements to the source of positrons in the galactic centre

International Nuclear Information System (INIS)

Aharonyan, F.A.

1986-01-01

The main requirements, following from the observational data in a wide range of electromagnetic waves, to positron source in the galactic centre are formulated. The most probable mechanism providing an efficiency of positron production of 10% is the pair production at photon-photon collisions. This mechanism can be realized a) in a thermal e + e - pair-dominated weak-relativistic plasma and b) at the development of a nonthermal electromagnetic cascade initiated by relativistic particles in the field of X-rays. Gamma-astronomical observations in the region of E γ ≥ 10 11 eV can be crucial in the choice of the model

Optimization of superconducting bending magnets for a 1.0 to 1.5 GeV compact light source

International Nuclear Information System (INIS)

Green, M.A.; Garren, A.A.

1995-06-01

Compact light sources are being proposed for protein crystallography, medical imaging, nano-machining and other areas of study that require intense sources of x rays at energies up to 35 keV. In order for a synchrotron light source to be attractive, its capital cost must, be kept low. The proposed compact light source has superconducting bending elements to bend the stored beam and produce the x rays. Additional focusing for the machine is provided by conventional quadrupoles. An important part of the cost optimization of a compact light source is the cost of the bending magnets. In the case of a machine with superconducting bending elements, the bending magnet system can represent close to half of the storage ring cost. The compact light source storage rings studied here have a range of stored electron energies from 1.0 to 1.5 GeV. For a number of reasons, it is desirable to keep the storage ring circumference below 30 meters. Cost optimization parameters include: (1) the number of superconducting bending elements in the ring, and (2) the central induction of the dipole. A machine design that features two superconducting dipoles in a single cryostat vacuum vessel is also discussed

A study of faint radio sources near the North Galactic Pole

International Nuclear Information System (INIS)

Benn, C.R.

1981-09-01

A large amount of observational data has been obtained on faint radio sources in a small area of sky near the North Galactic Pole (the 5C 12 area). This provides a new perspective (3 decades in flux density from the 3CR catalogue) on the physical properties and cosmological evolution of extragalactic radio sources. Chapter 1 introduces the problem and concludes that faint-object cosmology is best served by intensive investigation of sources in a small area of sky. An optimum area is chosen, at right ascension 12sup(h) 58sup(m) 43sup(s) and declination 35 0 14' 00'' (1950.0). Chapter 2 describes the 5C12 radio survey (complete to 9mJy apparent flux density at 408MHz) conducted with the One Mile Telescope at Cambridge. Chapter 4 describes a 4.85GHz survey to 20mJy of the area, conducted at Effelsberg. In chapter 5, a program of optical identification for the sources is described, using deep (msub(g) = 22.5, msub(y) = 20.7) Schmidt plates taken at Hale Observatories. A statistical algorithm is developed to cope with the problems of optical confusion due to radio positional errors. Chapter 6 draws on data from the previous 4, and presents results concerning radio source counts, spectral index distributions, optical identifications and clustering. (author)

Oscillating neutrinos from the Galactic center

International Nuclear Information System (INIS)

Crocker, R.M.; Volkas, R.R.; Melia, F.

1999-11-01

It has recently been demonstrated that the γ-ray emission spectrum of the EGRET-identified, central Galactic source 2EG J1746-2852 can be well fitted by positing that these photons are generated by the decay of π 0, s produced in p-p scattering at or near an energizing shock. Such scattering also produces charged pions which decay leptonically. The ratio of γ-rays to neutrinos generated by the central Galactic source may be accurately determined and a well-defined and potentially-measurable high energy neutrino flux at Earth is unavoidable. An opportunity, therefore, to detect neutrino oscillations over an unprecedented scale is offered by this source. In this paper we assess the prospects for such an observation with the generation of neutrino Cerenkov telescopes now in the planning stage. We determine that the next generation of detectors may find an oscillation signature in the Galactic Center (GC) signal, but that such an observation will probably not further constrain the oscillation parameter space mapped out by current atmospheric, solar, reactor and accelerator neutrino oscillation experiments

A VLA SURVEY FOR FAINT COMPACT RADIO SOURCES IN THE ORION NEBULA CLUSTER

Energy Technology Data Exchange (ETDEWEB)

Sheehan, Patrick D.; Eisner, Josh A. [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Mann, Rita K. [National Research Council Canada, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Williams, Jonathan P., E-mail: psheehan@email.arizona.edu [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

2016-11-10

We present Karl G. Jansky Very Large Array 1.3, 3.6, and 6 cm continuum maps of compact radio sources in the Orion Nebular Cluster (ONC). We mosaicked 34 arcmin{sup 2} at 1.3 cm, 70 arcmin{sup 2} at 3.6 cm and 109 arcmin{sup 2} at 6 cm, containing 778 near-infrared detected young stellar objects and 190 Hubble Space Telescope -identified proplyds (with significant overlap between those characterizations). We detected radio emission from 175 compact radio sources in the ONC, including 26 sources that were detected for the first time at these wavelengths. For each detected source, we fitted a simple free–free and dust emission model to characterize the radio emission. We extrapolate the free–free emission spectrum model for each source to ALMA bands to illustrate how these measurements could be used to correctly measure protoplanetary disk dust masses from submillimeter flux measurements. Finally, we compare the fluxes measured in this survey with previously measured fluxes for our targets, as well as four separate epochs of 1.3 cm data, to search for and quantify the variability of our sources.

TESTING THE GLOBAL STAR FORMATION RELATION: AN HCO+ (3-2) MAPPING STUDY OF RED MSX SOURCES IN THE BOLOCAM GALACTIC PLANE SURVEY

International Nuclear Information System (INIS)

Schenck, David E.; Shirley, Yancy L.; Reiter, Megan; Juneau, Stephanie

2011-01-01

We present an analysis of the relation between the star formation rate (SFR) and mass of dense gas in Galactic clumps and nearby galaxies. Using the bolometric luminosity as a measure of SFR and the molecular line luminosity of HCO + (3-2) as a measure of dense gas mass, we find that the relation between SFR and M dense is approximately linear. This is similar to published results derived using HCN (1-0) as a dense gas tracer. HCO + (3-2) and HCN (1-0) have similar conditions for excitation. Our work includes 16 Galactic clumps that are in both the Bolocam Galactic Plane Survey and the Red MSX Source Survey, 27 water maser sources from the literature, and the aforementioned HCN (1-0) data. Our results agree qualitatively with predictions of recent theoretical models which state that the nature of the relation should depend on how the critical density of the tracer compares with the mean density of the gas.

A COMPACT GROUP OF GALAXIES AT Z = 2.48 HOSTING AN AGN-DRIVEN OUTFLOW

Energy Technology Data Exchange (ETDEWEB)

Shih, Hsin-Yi [Gemini Observatory, 670 N Aohoku Place, Hilo, HI 96720 (United States); Stockton, Alan, E-mail: jshih@gemini.edu, E-mail: stockton@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2015-12-10

We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 10{sup 11}M{sub ⊙} and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass–metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow.

Galactic structure and gamma radiation

International Nuclear Information System (INIS)

Casse, Michel; Cesarsky, Catherine; Paul Jacques

1977-01-01

A model of spiral structure of the Galaxy is outlined from radiosynchrotron and gamma observations. The most interesting observations in the galactic context, obtained by the SAS II American satellite are concerned with the distribution of the γ photoemission at energies higher than 10 8 eV, along the galactic equator. The model proposed is in quantitative agreement with the present ideas on the spiral structure of the Galaxy, the galactic magnetic field, and the confinement of cosmic rays by the magnetic field and of the magnetic field by matter. Following the American era, the European COS-B satellite opens the European phase towards an identification of the discrete gamma radiation sources [fr

The first VLBI image of an infrared-faint radio source

Science.gov (United States)

Middelberg, E.; Norris, R. P.; Tingay, S.; Mao, M. Y.; Phillips, C. J.; Hotan, A. W.

2008-11-01

Context: We investigate the joint evolution of active galactic nuclei and star formation in the Universe. Aims: In the 1.4 GHz survey with the Australia Telescope Compact Array of the Chandra Deep Field South and the European Large Area ISO Survey - S1 we have identified a class of objects which are strong in the radio but have no detectable infrared and optical counterparts. This class has been called Infrared-Faint Radio Sources, or IFRS. 53 sources out of 2002 have been classified as IFRS. It is not known what these objects are. Methods: To address the many possible explanations as to what the nature of these objects is we have observed four sources with the Australian Long Baseline Array. Results: We have detected and imaged one of the four sources observed. Assuming that the source is at a high redshift, we find its properties in agreement with properties of Compact Steep Spectrum sources. However, due to the lack of optical and infrared data the constraints are not particularly strong.

THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS

International Nuclear Information System (INIS)

Rupke, David S. N.; Veilleux, Sylvain

2013-01-01

Massive, galaxy-scale outflows are known to be ubiquitous in major mergers of disk galaxies in the local universe. In this paper, we explore the multiphase structure and power sources of galactic winds in six ultraluminous infrared galaxies (ULIRGs) at z –1 , and the highest velocities (2000-3000 km s –1 ) are seen only in ionized gas. The outflow energy and momentum in the QSOs are difficult to produce from a starburst alone, but are consistent with the QSO contributing significantly to the driving of the flow. Finally, when all gas phases are accounted for, the outflows are massive enough to provide negative feedback to star formation.

Development of a compact permanent magnet helicon plasma source for ion beam bioengineering

Energy Technology Data Exchange (ETDEWEB)

Kerdtongmee, P.; Srinoum, D.; Nisoa, M. [Plasma Technology for Agricultural Applications Research Laboratory, School of Science, Walailak University, Nakhon Si Thammarat 80161 (Thailand); ThEP Center, CHE, 328 Si Ayutthaya Rd., Bangkok 10400 (Thailand)

2011-10-15

A compact helicon plasma source was developed as a millimeter-sized ion source for ion beam bioengineering. By employing a stacked arrangement of annular-shaped permanent magnets, a uniform axial magnetic flux density up to 2.8 kG was obtained. A cost effective 118 MHz RF generator was built for adjusting forward output power from 0 to 40 W. The load impedance and matching network were then analyzed. A single loop antenna and circuit matching elements were placed on a compact printed circuit board for 50 {Omega} impedance matching. A plasma density up to 1.1 x 10{sup 12} cm{sup -3} in the 10 mm diameter tube under the magnetic flux density was achieved with 35 W applied RF power.

Development of a compact permanent magnet helicon plasma source for ion beam bioengineering.

Science.gov (United States)

Kerdtongmee, P; Srinoum, D; Nisoa, M

2011-10-01

A compact helicon plasma source was developed as a millimeter-sized ion source for ion beam bioengineering. By employing a stacked arrangement of annular-shaped permanent magnets, a uniform axial magnetic flux density up to 2.8 kG was obtained. A cost effective 118 MHz RF generator was built for adjusting forward output power from 0 to 40 W. The load impedance and matching network were then analyzed. A single loop antenna and circuit matching elements were placed on a compact printed circuit board for 50 Ω impedance matching. A plasma density up to 1.1 × 10(12) cm(-3) in the 10 mm diameter tube under the magnetic flux density was achieved with 35 W applied RF power.

RESOLUTION OF THE COMPACT RADIO CONTINUUM SOURCES IN Arp220

International Nuclear Information System (INIS)

Batejat, Fabien; Conway, John E.; Hurley, Rossa; Parra, Rodrigo; Diamond, Philip J.; Lonsdale, Colin J.; Lonsdale, Carol J.

2011-01-01

We present 2 cm and 3.6 cm wavelength very long baseline interferometry images of the compact radio continuum sources in the nearby ultra-luminous infrared galaxy Arp220. Based on their radio spectra and variability properties, we confirm these sources to be a mixture of supernovae (SNe) and supernova remnants (SNRs). Of the 17 detected sources we resolve 7 at both wavelengths. The SNe generally only have upper size limits. In contrast all the SNRs are resolved with diameters ≥0.27 pc. This size limit is consistent with them having just entered their Sedov phase while embedded in an interstellar medium (ISM) of density 10 4 cm -3 . These objects lie on the diameter-luminosity correlation for SNRs (and so also on the diameter-surface brightness relation) and extend these correlations to very small sources. The data are consistent with the relation L∝D -9/4 . Revised equipartition arguments adjusted to a magnetic field to a relativistic particle energy density ratio of 1% combined with a reasonable synchrotron-emitting volume filling factor of 10% give estimated magnetic field strengths in the SNR shells of ∼15-50 mG. The SNR shell magnetic fields are unlikely to come from compression of ambient ISM fields and must instead be internally generated. We set an upper limit of 7 mG for the ISM magnetic field. The estimated energy in relativistic particles, 2%-20% of the explosion kinetic energy, is consistent with estimates from models that fit the IR-radio correlation in compact starburst galaxies.

A CLUSTER OF COMPACT RADIO SOURCES IN W40

International Nuclear Information System (INIS)

RodrIguez, Luis F.; Rodney, Steven A.; Reipurth, Bo

2010-01-01

We present deep 3.6 cm radio continuum observations of the H II region W40 obtained using the Very Large Array (VLA) in its A and B configurations. We detect a total of 20 compact radio sources in a region of 4' x 4', with 11 of them concentrated in a band with 30'' of extent. We also present JHK photometry of the W40 cluster taken with the QUIRC instrument on the University of Hawaii 2.2 m telescope. These data reveal that 15 of the 20 VLA sources have infrared counterparts, and 10 show radio variability with periods less than 20 days. Based on these combined radio and IR data, we propose that eight of the radio sources are candidate ultracompact H II regions, seven are likely to be young stellar objects, and two may be shocked interstellar gas.

CO Spectral Line Energy Distributions in Galactic Sources: Empirical Interpretation of Extragalactic Observations

Energy Technology Data Exchange (ETDEWEB)

Indriolo, Nick; Bergin, E. A. [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Goicoechea, J. R.; Cernicharo, J. [Grupo de Astrofísica Molecular, Instituto de Ciencia de Materiales de Madrid (CSIC) E-28049 Madrid (Spain); Gerin, M.; Gusdorf, A. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, École normale supérieure, F-75005, Paris (France); Lis, D. C. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75014, Paris (France); Schilke, P., E-mail: nindriolo@stsci.edu [I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany)

2017-02-10

The relative populations in rotational transitions of CO can be useful for inferring gas conditions and excitation mechanisms at work in the interstellar medium. We present CO emission lines from rotational transitions observed with Herschel /HIFI in the star-forming cores Orion S, Orion KL, Sgr B2(M), and W49N. Integrated line fluxes from these observations are combined with those from Herschel /PACS observations of the same sources to construct CO spectral line energy distributions (SLEDs) from 5≤ J{sub u} ≤ 48. These CO SLEDs are compared to those reported in other galaxies, with the intention of empirically determining which mechanisms dominate excitation in such systems. We find that CO SLEDs in Galactic star-forming cores cannot be used to reproduce those observed in other galaxies, although the discrepancies arise primarily as a result of beam filling factors. The much larger regions sampled by the Herschel beams at distances of several megaparsecs contain significant amounts of cooler gas, which dominate the extragalactic CO SLEDs, in contrast to observations of Galactic star-forming regions, which are focused specifically on cores containing primarily hot molecular gas.

Prospects for identifying the sources of the Galactic cosmic rays with IceCube

International Nuclear Information System (INIS)

Halzen, Francis; Kappes, Alexander; O Murchadha, Aongus

2008-01-01

We quantitatively address whether IceCube, a kilometer-scale neutrino detector under construction at the South Pole, can observe neutrinos pointing back at the accelerators of the Galactic cosmic rays. The photon flux from candidate sources identified by the Milagro detector in a survey of the TeV sky is consistent with the flux expected from a typical cosmic-ray generating supernova remnant interacting with the interstellar medium. We show here that IceCube can provide incontrovertible evidence of cosmic-ray acceleration in these sources by detecting neutrinos. We find that the signal is optimally identified by specializing to events with energies above 30 TeV where the atmospheric neutrino background is low. We conclude that evidence for a correlation between the Milagro and IceCube sky maps should be conclusive after several years.

Compact deuterium-tritium neutron generator using a novel field ionization source

Energy Technology Data Exchange (ETDEWEB)

Ellsworth, J. L., E-mail: ellsworth7@llnl.gov; Falabella, S.; Sanchez, J.; Tang, V. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Wang, H. [Department of Computer Science, Stanford University, Stanford, California 94305 (United States)

2014-11-21

Active interrogation using neutrons is an effective method for detecting shielded nuclear material. A lightweight, lunch-box-sized, battery-operated neutron source would enable new concepts of operation in the field. We have developed at-scale components for a highly portable, completely self-contained, pulsed Deuterium-Tritium (DT) neutron source producing 14 MeV neutrons with average yields of 10{sup 7} n/s. A gated, field ionization ion source using etched electrodes has been developed that produces pulsed ion currents up to 500 nA. A compact Cockcroft-Walton high voltage source is used to accelerate deuterons into a metal hydride target for neutron production. The results of full scale DT tests using the field ionization source are presented.

Diffuse γ-ray emission from galactic pulsars

International Nuclear Information System (INIS)

Calore, F.; Di Mauro, M.; Donato, F.

2014-01-01

Millisecond pulsars (MSPs) are old fast-spinning neutron stars that represent the second most abundant source population discovered by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi). As guaranteed γ-ray emitters, they might contribute non-negligibly to the diffuse emission measured at high latitudes by Fermi-LAT (i.e., the Isotropic Diffuse γ-Ray Background (IDGRB)), which is believed to arise from the superposition of several components of galactic and extragalactic origin. Additionally, γ-ray sources also contribute to the anisotropy of the IDGRB measured on small scales by Fermi-LAT. In this manuscript we aim to assess the contribution of the unresolved counterpart of the detected MSPs population to the IDGRB and the maximal fraction of the measured anisotropy produced by this source class. To this end, we model the MSPs' spatial distribution in the Galaxy and the γ-ray emission parameters by considering observational constraints coming from the Australia Telescope National Facility pulsar catalog and the Second Fermi-LAT Catalog of γ-ray pulsars. By simulating a large number of MSP populations through a Monte Carlo simulation, we compute the average diffuse emission and the anisotropy 1σ upper limit. We find that the emission from unresolved MSPs at 2 GeV, where the peak of the spectrum is located, is at most 0.9% of the measured IDGRB above 10° in latitude. The 1σ upper limit on the angular power for unresolved MSP sources turns out to be about a factor of 60 smaller than Fermi-LAT measurements above 30°. Our results indicate that this galactic source class represents a negligible contributor to the high-latitude γ-ray sky and confirm that most of the intensity and geometrical properties of the measured diffuse emission are imputable to other extragalactic source classes (e.g., blazars, misaligned active galactic nuclei, or star-forming galaxies). Nevertheless, because MSPs are more concentrated toward the

Magnetic braking in galactic flows

International Nuclear Information System (INIS)

Sparke, L.S.

1982-01-01

The nuclear fireworks of active galaxies are believed to derive their power from the kinetic energy of gas falling onto a massive central objects; mass shed from evolving galactic stars is an obvious source of fuel for this process. But this ejected material shares the galactic rotation, and a centrifugal barrier will prevent it from reaching the nucleus, if its angular momentum is not removed. This paper shows that, if the large-scale galactic magnetic field has a strong enough radial component, magnetic torques can act to spin down the infalling matter. Rotation of the interstellar gas induces a toroidal magnetic field, and Maxwell stresses remove angular momentum from the flow; gas can then fall inward to the galactic center. In this way, the monster in the nucleus can be fed on gas from a galaxy's own stars. The magnetic fields in M87 and NGC 1275, giant elliptical galaxies which are accreting from an intracluster medium, appear to be strong enough to allow magnetic braking

Compact permanent magnet H⁺ ECR ion source with pulse gas valve.

Science.gov (United States)

Iwashita, Y; Tongu, H; Fuwa, Y; Ichikawa, M

2016-02-01

Compact H(+) ECR ion source using permanent magnets is under development. Switching the hydrogen gas flow in pulse operations can reduce the gas loads to vacuum evacuation systems. A specially designed piezo gas valve chops the gas flow quickly. A 6 GHz ECR ion source equipped with the piezo gas valve is tested. The gas flow was measured by a fast ion gauge and a few ms response time is obtained.

Probing the Galactic Structure of the Milky Way with H II Regions

Science.gov (United States)

Red, Wesley Alexander; Wenger, Trey V.; Balser, Dana; Anderson, Loren; Bania, Thomas

2018-01-01

Mapping the structure of the Milky Way is challenging since we reside within the Galactic disk and distances are difficult to determine. Elemental abundances provide important constraints on theories of the formation and evolution of the Milky Way. HII regions are the brightest objects in the Galaxy at radio wavelengths and are detected across the entire Galactic disk. We use the Jansky Very Large Array (VLA) to observe the radio recombination line (RRL) and continuum emission of 120 Galactic HII regions located across the Galactic disk. In thermal equilibrium, metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. We derive the metallicity of HII regions using an empirical relation between an HII region's radio recombination line-to-continuum ratio and nebular metallicity. Here we focus on a subset of 20 HII regions from our sample that have been well studied with the Green Bank Telescope (GBT) to test our data reduction pipeline and analysis methods. Our goal is to expand this study to the Southern skies with the Australia Telescope Compact Array and create a metallicity map of the entire Galactic disk.

INVISIBLE ACTIVE GALACTIC NUCLEI. II. RADIO MORPHOLOGIES AND FIVE NEW H i 21 cm ABSORPTION LINE DETECTORS

Energy Technology Data Exchange (ETDEWEB)

Yan, Ting; Stocke, John T.; Darling, Jeremy [Center for Astrophysics and Space Astronomy, UCB 389, University of Colorado, Boulder, CO 80309-0389 (United States); Momjian, Emmanuel [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Sharma, Soniya [Research School of Astronomy and Astrophysics, The Australian National University, Mt Stromlo Observatory, ACT 2611 (Australia); Kanekar, Nissim [National Centre for Radio Astrophysics, TIFR, Post Bag 3, Ganeshkhind, Pune 411 007 (India)

2016-03-15

This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.″5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral “window” (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by

Galactic binaries with eLISA

OpenAIRE

Nelemans, G.

2013-01-01

I review what eLISA will see from Galactic binaries -- double stars with orbital periods less than a few hours and white dwarf (or neutron star/black hole) components. I discuss the currently known binaries that are guaranteed (or verification) sources and explain why the expected total number of eLISA Galactic binaries is several thousand, even though there are large uncertainties in our knowledge of this population, in particular that of the interacting AM CVn systems. I very briefly sketch...

Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Yoshimasa, E-mail: yoshimasa.ikeda@riken.jp [Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan); Taketani, Atsushi; Takamura, Masato; Sunaga, Hideyuki [Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan); Kumagai, Masayoshi [Faculty of Engineering, Tokyo City University, Setagaya, Tokyo 158-8857 (Japan); Oba, Yojiro [Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494 (Japan); Otake, Yoshie [Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan); Suzuki, Hiroshi [Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

2016-10-11

A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by a large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 min. The minimum resolution of the 110 reflection for RANS is approximately 2.5% at 8 μs of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 μs, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time by decreasing a thickness of the moderator or by applying the decoupler system or application of the angular dispersive neutron diffraction technique are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenitic phase in the dual phase mock specimen was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS has been proved to be capable for neutron engineering diffraction aiming for the easy access

A Compact, High-Flux Cold Atom Beam Source

Science.gov (United States)

Kellogg, James R.; Kohel, James M.; Thompson, Robert J.; Aveline, David C.; Yu, Nan; Schlippert, Dennis

2012-01-01

The performance of cold atom experiments relying on three-dimensional magneto-optical trap techniques can be greatly enhanced by employing a highflux cold atom beam to obtain high atom loading rates while maintaining low background pressures in the UHV MOT (ultra-high vacuum magneto-optical trap) regions. Several techniques exist for generating slow beams of cold atoms. However, one of the technically simplest approaches is a two-dimensional (2D) MOT. Such an atom source typically employs at least two orthogonal trapping beams, plus an additional longitudinal "push" beam to yield maximum atomic flux. A 2D atom source was created with angled trapping collimators that not only traps atoms in two orthogonal directions, but also provides a longitudinal pushing component that eliminates the need for an additional push beam. This development reduces the overall package size, which in turn, makes the 2D trap simpler, and requires less total optical power. The atom source is more compact than a previously published effort, and has greater than an order of magnitude improved loading performance.

Development of Compact Soft X-ray Source Based on Laser Undulator

CERN Document Server

Kuroda, Ryunosuke; Minamiguchi, S; Saitô, T; Ueyama, D; Washio, Masakazu

2004-01-01

A compact soft X-ray source is required in various research fields such as material and biological science. The laser undulator based on backward Compton scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. It is performed in a water window region (250eV - 500 eV) using the interaction between 1047 nm Nd:YLF laser and 4 MeV high quality electron beam generated from rf gun system. The range of energy in the water window region has K-shell absorption edges of Oxygen, Carbon and Nitrogen, which mainly constitute of living body. Since the absorption coefficient of water is much smaller than the protein’s coefficient in this range, a dehydration of the specimens is not necessary. As a preliminary experiment, about 300 eV X-ray generation was carried out. As next step, soft X-ray optics with zone plate was proposed for Soft X-ray microscopy. In this conference, we will report details and results of the experiment.

Compact, self-regulating nuclear power source

International Nuclear Information System (INIS)

Peterson, Otis G.; Kimpland, Robert H.

2008-01-01

An inherently safe nuclear power source has been designed, that is self-stabilizing and requires no moving mechanical components. Unlike conventional designs, the proposed reactor is self-regulating through the inherent properties of uranium hydride, which serves as a combination fuel and moderator. The temperature driven mobility of the hydrogen contained in the hydride will control the nuclear activity. If the core temperature increases over the set point, the hydrogen is driven out of the core, the moderation drops and the power production decreases. If the temperature drops, the hydrogen returns and the process is reversed. Thus the design is inherently fail-safe and requires only minimal human oversight. The compact nature and inherent safety opens the possibility for low-cost mass production and operation of the reactors. This design has the capability to dramatically alter the manner in which nuclear energy is harnessed for commercial use. (author)

Black holes in binary stellar systems and galactic nuclei

International Nuclear Information System (INIS)

Cherepashchuk, A M

2014-01-01

In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M BH =(4−20)M ⊙ ) in X-ray binary systems and of several hundred supermassive black holes (M BH =(10 6 −10 10 )M ⊙ ) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a ∗ have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a ∗ =0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths λ≲1 mm (the international program, Event Horizon Telescope). (100

Black holes in binary stellar systems and galactic nuclei

Science.gov (United States)

Cherepashchuk, A. M.

2014-04-01

In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M_BH = (4{-}20) M_\\odot) in X-ray binary systems and of several hundred supermassive black holes (M_BH = (10^{6}{-}10^{10}) M_\\odot) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a_* have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a_* = 0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths \\lambda \\lesssim 1 mm (the international program, Event Horizon Telescope).

Research opportunities with compact accelerator-driven neutron sources

Energy Technology Data Exchange (ETDEWEB)

Anderson, I.S. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Andreani, C., E-mail: carla.andreani@uniroma2.it [Università degli Studi di Roma “Tor Vergata”, Physics Department and NAST Centre, Via della Ricerca Scientifica 1, 00133 Roma (Italy); CNR-IPCF Sezione di Messina, Messina (Italy); Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma (Italy); Carpenter, J.M. [Argonne National Laboratory, Argonne, IL (United States); Festa, G., E-mail: giulia.festa@uniroma2.it [Università degli Studi di Roma “Tor Vergata”, Physics Department and NAST Centre, Via della Ricerca Scientifica 1, 00133 Roma (Italy); Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma (Italy); Gorini, G. [Università degli Studi di Milano—Bicocca, Milano (Italy); Loong, C.-K. [Università degli Studi di Roma “Tor Vergata”, Centro NAST, Via della Ricerca Scientifica 1, 00133 Roma (Italy); Senesi, R. [Università degli Studi di Roma “Tor Vergata”, Physics Department and NAST Centre, Via della Ricerca Scientifica 1, 00133 Roma (Italy); CNR-IPCF Sezione di Messina, Messina (Italy); Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma (Italy)

2016-10-13

Since the discovery of the neutron in 1932 neutron beams have been used in a very broad range of applications, As an aging fleet of nuclear reactor sources is retired the use of compact accelerator-driven neutron sources (CANS) is becoming more prevalent. CANS are playing a significant and expanding role in research and development in science and engineering, as well as in education and training. In the realm of multidisciplinary applications, CANS offer opportunities over a wide range of technical utilization, from interrogation of civil structures to medical therapy to cultural heritage study. This paper aims to provide the first comprehensive overview of the history, current status of operation, and ongoing development of CANS worldwide. The basic physics and engineering regarding neutron production by accelerators, target–moderator systems, and beam line instrumentation are introduced, followed by an extensive discussion of various evolving applications currently exploited at CANS.

Research opportunities with compact accelerator-driven neutron sources

International Nuclear Information System (INIS)

Anderson, I.S.; Andreani, C.; Carpenter, J.M.; Festa, G.; Gorini, G.; Loong, C.-K.; Senesi, R.

2016-01-01

Since the discovery of the neutron in 1932 neutron beams have been used in a very broad range of applications, As an aging fleet of nuclear reactor sources is retired the use of compact accelerator-driven neutron sources (CANS) is becoming more prevalent. CANS are playing a significant and expanding role in research and development in science and engineering, as well as in education and training. In the realm of multidisciplinary applications, CANS offer opportunities over a wide range of technical utilization, from interrogation of civil structures to medical therapy to cultural heritage study. This paper aims to provide the first comprehensive overview of the history, current status of operation, and ongoing development of CANS worldwide. The basic physics and engineering regarding neutron production by accelerators, target–moderator systems, and beam line instrumentation are introduced, followed by an extensive discussion of various evolving applications currently exploited at CANS.

Research opportunities with compact accelerator-driven neutron sources

Science.gov (United States)

Anderson, I. S.; Andreani, C.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C.-K.; Senesi, R.

2016-10-01

Since the discovery of the neutron in 1932 neutron beams have been used in a very broad range of applications, As an aging fleet of nuclear reactor sources is retired the use of compact accelerator-driven neutron sources (CANS) is becoming more prevalent. CANS are playing a significant and expanding role in research and development in science and engineering, as well as in education and training. In the realm of multidisciplinary applications, CANS offer opportunities over a wide range of technical utilization, from interrogation of civil structures to medical therapy to cultural heritage study. This paper aims to provide the first comprehensive overview of the history, current status of operation, and ongoing development of CANS worldwide. The basic physics and engineering regarding neutron production by accelerators, target-moderator systems, and beam line instrumentation are introduced, followed by an extensive discussion of various evolving applications currently exploited at CANS.

Evolution of Supernova Remnants Near the Galactic Center

Energy Technology Data Exchange (ETDEWEB)

Yalinewich, A.; Piran, T.; Sari, R. [Racah Institute of Physics, the Hebrew University, 91904, Jerusalem (Israel)

2017-03-20

Supernovae near the Galactic center (GC) evolve differently from regular Galactic supernovae. This is mainly due to the environment into which the supernova remnants (SNRs) propagate. SNRs near the GC propagate into a wind swept environment with a velocity directed away from the GC, and a graded density profile. This causes these SNRs to be non-spherical, and to evolve faster than their Galactic counterparts. We develop an analytic theory for the evolution of explosions within a stellar wind, and verify it using a hydrodynamic code. We show that such explosions can evolve in one of three possible morphologies. Using these results we discuss the association between the two SNRs (SGR East and SGR A’s bipolar radio/X-ray lobes) and the two neutron stars (the Cannonball and SGR J1745-2900) near the GC. We show that, given the morphologies of the SNR and positions of the neutron stars, the only possible association is between SGR A’s bipolar radio/X-ray lobes and SGR J1745-2900. If a compact object was created in the explosion of SGR East, it remains undetected, and the SNR of the supernova that created the Cannonball has already disappeared.

A compact neutron generator using a field ionization source.

Science.gov (United States)

Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas

2012-02-01

Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-fibers promise the high field-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of field emitters with a density up to 10(6) tips∕cm(2) and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.

Positron Transport and Annihilation in the Galactic Bulge

Directory of Open Access Journals (Sweden)

Fiona Helen Panther

2018-03-01

Full Text Available The annihilation of positrons in the Milky Way Galaxy has been observed for ∼50 years; however, the production sites of these positrons remains hard to identify. The observed morphology of positron annihilation gamma-rays provides information on the annihilation sites of these Galactic positrons. It is understood that the positrons responsible for the annihilation signal originate at MeV energies. The majority of sources of MeV positrons occupy the star-forming thin disk of the Milky Way. If positrons propagate far from their sources, we must develop accurate models of positron propagation through all interstellar medium (ISM phases in order to reveal the currently uncertain origin of these Galactic positrons. On the other hand, if positrons annihilate close to their sources, an alternative source of MeV positrons with a distribution that matches the annihilation morphology must be identified. In this work, I discuss the various models that have been developed to understand the origin of the 511 keV line from the direction of the Galactic bulge, and the propagation of positrons in the ISM.

The INTEGRAL Galactic bulge monitoring program: the first 1.5 years

NARCIS (Netherlands)

Kuulkers, E.; Shaw, S.E.; Paizis, A.; Chenevez, J.; Brandt, S.; Courvoisier, T.J.L.; Domingo, A.; Ebisawa, K.; Kretschmar, P.; Markwardt, C.B.; Mowlavi, N.; Oosterbroek, T.; Orr, A.; Rísquez, D.; Sanchez-Fernandez, C.; Wijnands, R.

2007-01-01

Aims.The Galactic bulge region is a rich host of variable high-energy point sources. Since 2005, February 17 we are monitoring the source activity in the Galactic bulge region regularly and frequently, i.e., about every three days, with the instruments onboard INTEGRAL. Thanks to the large field of

X-Ray Processing of ChaMPlane Fields: Methods and Initial Results for Selected Anti-Galactic Center Fields

Science.gov (United States)

Hong, JaeSub; van den Berg, Maureen; Schlegel, Eric M.; Grindlay, Jonathan E.; Koenig, Xavier; Laycock, Silas; Zhao, Ping

2005-12-01

We describe the X-ray analysis procedure of the ongoing Chandra Multiwavelength Plane (ChaMPlane) Survey and report the initial results from the analysis of 15 selected anti-Galactic center observations (90degusing custom-developed analysis tools appropriate for Galactic sources but also of general use: optimum photometry in crowded fields using advanced techniques for overlapping sources, rigorous astrometry and 95% error circles for combining X-ray images or matching to optical/IR images, and application of quantile analysis for spectral analysis of faint sources. We apply these techniques to 15 anti-Galactic center observations (of 14 distinct fields), in which we have detected 921 X-ray point sources. We present logN-logS distributions and quantile analysis to show that in the hard band (2-8 keV) active galactic nuclei dominate the sources. Complete analysis of all ChaMPlane anti-Galactic center fields will be given in a subsequent paper, followed by papers on sources in the Galactic center and bulge regions.

Evolution of hot galactic flows

International Nuclear Information System (INIS)

Loewenstein, M.; Mathews, W.G.

1987-01-01

The time-dependent equations describing galactic flows, including detailed models for the evolving source terms, are integrated over a Hubble time for two elliptical galaxies with total masses of 3.1 x 10 to the 12th and 8.3 x 10 to the 12th solar masses, 90 percent of which resides in extended, nonluminous halos. The standard supernova rate of Tammann and a rate 4 times smaller are considered for each galaxy model. The combination of the extended gravitational potential of the dark halo and the time-dependent source terms generally lead to the development of massive, quasi-hydrostatic, nearly isothermal distributions of gas at about 10 to the 7th K with cooling inflows inside their galactic cores. For the less massive galaxy with the higher supernova rate, however, a low-luminosity supersonic galactic wind develops. The effects of a lowered metal abundance, thermal conduction, and the absence of a massive halo are explored separately for one of the present models. The X-ray luminosities of the hot gas in the models with dark halos and the lower supernova rate are in good agreement with Einstein observations of early-type galaxies. 42 references

Interstellar scattering of the compact radio source 2005 + 403

International Nuclear Information System (INIS)

Mutel, R.L.; Lestrade, J.

1990-01-01

Analysis of Mk III VLBI visibility amplitudes of the compact radio source 2005 + 403 shows an excess at baselines greater than a few diffractive scale lengths compared with that expected from formulas using ensemble-averaged quantities and power-law turbulence with quasi-Kolmogorov spectral indices. The data are in good agreement with the 1989 analysis of Goodman and Narayan, who find that measured visibility amplitudes correspond to the average visibility regime, which differs significantly from the ensemble-averaged results for baselines much longer than one diffractive scale length. 20 refs

Theories of magnetospheres around accreting compact objects

International Nuclear Information System (INIS)

Vasyliunas, V.M.

1979-01-01

A wide class of galactic X-ray sources are believed to be binary systems where mass is flowing from a normal star to a companion that is a compact object, such as a neutron star. The strong magnetic fields of the compact object create a magnetosphere around it. We review the theoretical models developed to describe the properties of magnetospheres in such accreting binary systems. The size of the magnetosphere can be estimated from pressure balance arguments and is found to be small compared to the over-all size of the accretion region but large compared object if the latter is a neutron star. In the early models the magnetosphere was assumed to have open funnels in the polar regions, through which accreting plasma could pour in. Later, magnetically closed models were developed, with plasma entry made possible by instabilities at the magnetosphere boundary. The theory of plasma flow inside the magnetosphere has been formulated in analogy to a stellar wind with reversed flow; a complicating factor is the instability of the Alfven critical point for inflow. In the case of accretion via a well-defined disk, new problems if magnetospheric structure appear, in particular the question to what extent and by what process the magnetic fields from the compact object can penetrate into the acretion disk. Since the X-ray emission is powered by the gravitational energy released in the accretion process, mass transfer into the magnetosphere is of fundamental importance; the various proposed mechanisms are critically examined. (orig.)

NuSTAR Observations of the Compton-Thick Active Galactic Nucleus and Ultraluminous X-Ray Source Candidate in NGC 5643

DEFF Research Database (Denmark)

Annuar, A.; Gandhi, P.; Alexander, D. M.

2015-01-01

We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband s...

Gamma-ray evidence for a stellar-mass black hole near the Galatic Center

International Nuclear Information System (INIS)

Ramaty, R.; Lingenfelter, R.E.

1989-01-01

Observations at 511 keV and higher energies have provided evidence for a variable, compact source of annihilation radiation and >511-keV continuum emission at the Galactic Center or in its vicinity. The authors have reviewed this evidence. The strongest argument for the existence of this compact source is the time variation of the 511-keV line flux, inferred from observations at different times for over a decade. These observations include a recent detection of the 511-keV line showing that the compact source, after not being seen for nine years, has become active again. In addition to this compact source, there also is evidence for a distributed source of galactic 511-keV line emission. This is based on the comparison of observations with broad and narrow field- of-view detectors, as well as on a direct observation with a narrow field-of-view instrument pointing in the galactic plane away from the Galactic Center. Much remains to be learned about this emission from observations with improved angular and energy resolution. Such observations will provide new information on nucleosynthesis, supernovae, galactic structure, and the interstellar medium. However, in the present paper, the authors deal mainly with the compact source in an attempt to clarify the arguments that have led us to suggest that this object is a stellar-mass black hole. The authors review the technique that they have used to separate the compact and distributed sources, emphasizing the uncertainties caused by data obtained with very poor angular resolution. They show the time dependence of the 511-keV line emission and the >511-keV continuum and summarize the evidence that these two emissions are correlated

A 24 μm point source catalog of the galactic plane from Spitzer/MIPSGAL

Energy Technology Data Exchange (ETDEWEB)

Gutermuth, Robert A.; Heyer, Mark [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

2015-02-01

In this contribution, we describe the applied methods to construct a 24 μm based point source catalog derived from the image data of the MIPSGAL 24 μm Galactic Plane Survey and the corresponding data products. The high quality catalog product contains 933,818 sources, with a total of 1,353,228 in the full archive catalog. The source tables include positional and photometric information derived from the 24 μm images, source quality and confusion flags, and counterpart photometry from matched 2MASS, GLIMPSE, and WISE point sources. Completeness decay data cubes are constructed at 1′ angular resolution that describe the varying background levels over the MIPSGAL field and the ability to extract sources of a given magnitude from this background. The completeness decay cubes are included in the set of data products. We present the results of our efforts to verify the astrometric and photometric calibration of the catalog, and present several analyses of minor anomalies in these measurements to justify adopted mitigation strategies.

Multiwavelength observations of Active Galactic Nuclei from the radio to the hard X-rays

Science.gov (United States)

Beuchert, Tobias

2017-07-01

Active Galaxies form a peculiar type of galaxies. Their cores, the so-called "Active Galactic Nuclei" (AGN), are the most persistent luminous objects in the universe. Accretion of several solar masses per year onto black holes of Millions to Billions of solar masses drive the immense energy output of these systems, which can exceed that of the entire galaxy. The compact energy source, however, only measures about one over a Billion times that of the entire galaxy. Subject of my thesis are observations of the two main channels of energy release of selected AGN systems, both of which are encompassed by profound and yet unanswered questions. These channels are on the one hand the pronounced X-ray emission of the hot and compact accreting environment in close vicinity of the black hole, and on the other hand the radio synchrotron emission of magnetically collimated jets that are fed by portions of the accreted matter. These jets also function as effective accelerators and drive the injected matter deep into the intergalactic medium. As the circumnuclear environment of AGN is too compact to be spatially resolved in the X-rays, I show how X-ray spectroscopy can be used to: (1) understand the effects of strong gravity to trace the geometry and physics of the X-ray source and (2) more consistently quantify matter that surrounds and dynamically absorbs our direct line of sight towards the X-ray source. Second, I unveil the valuable information contained in the polarized radio light being emitted from magnetized jet outflows. In contrast to the X-ray emitting region, I am able to spatially resolve the inner parts of the jet of a prominent galaxy with help of the Very Long Baseline Array, a large network of radio telescopes. The resulting polarization maps turn out to be exceptionally promising in answering fundamental questions related to jet physics.

The Fermi Gamma Ray Space Telescope discovers the Pulsar in the Young Galactic Supernova-Remnant CTA 1

International Nuclear Information System (INIS)

Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M.G.; Bastieri, Denis; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, Elliott D.; Bogaert, G.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.

2009-01-01

Energetic young pulsars and expanding blast waves (supernova remnants, SNRs) are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. The pulsar, discovered through its gamma-ray pulsations, has a period of 316.86 ms, a period derivative of 3.614 x 10 -13 s s -1 . Its characteristic age of 10 4 years is comparable to that estimated for the SNR. It is conjectured that most unidentified Galactic gamma ray sources associated with star-forming regions and SNRs are such young pulsars

The Fermi Gamma Ray Space Telescope discovers the Pulsar in the Young Galactic Supernova-Remnant CTA 1

Energy Technology Data Exchange (ETDEWEB)

Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M.G.; Bastieri, Denis; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, Elliott D.; Bogaert, G.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.

2009-05-15

Energetic young pulsars and expanding blast waves (supernova remnants, SNRs) are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. The pulsar, discovered through its gamma-ray pulsations, has a period of 316.86 ms, a period derivative of 3.614 x 10{sup -13} s s{sup -1}. Its characteristic age of 10{sup 4} years is comparable to that estimated for the SNR. It is conjectured that most unidentified Galactic gamma ray sources associated with star-forming regions and SNRs are such young pulsars.

JVLA observations of IC 348 SW: Compact radio sources and their nature

Energy Technology Data Exchange (ETDEWEB)

Rodríguez, Luis F.; Zapata, Luis A.; Palau, Aina, E-mail: l.rodriguez@crya.unam.mx, E-mail: l.zapata@crya.unam.mx, E-mail: a.palau@crya.unam.mx [Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico)

2014-07-20

We present sensitive 2.1 and 3.3 cm Jansky Very Large Array radio continuum observations of the region IC 348 SW. We detect a total of 10 compact radio sources in the region, 7 of which are first reported here. One of the sources is associated with the remarkable periodic time-variable infrared source LRLL 54361, opening the possibility of monitoring this object at radio wavelengths. Four of the sources appear to be powering outflows in the region, including HH 211 and HH 797. In the case of the rotating outflow HH 797, we detect a double radio source at its center, separated by ∼3''. Two of the sources are associated with infrared stars that possibly have gyrosynchrotron emission produced in active magnetospheres. Finally, three of the sources are interpreted as background objects.

Radio Galaxy Zoo: compact and extended radio source classification with deep learning

Science.gov (United States)

Lukic, V.; Brüggen, M.; Banfield, J. K.; Wong, O. I.; Rudnick, L.; Norris, R. P.; Simmons, B.

2018-05-01

Machine learning techniques have been increasingly useful in astronomical applications over the last few years, for example in the morphological classification of galaxies. Convolutional neural networks have proven to be highly effective in classifying objects in image data. In the context of radio-interferometric imaging in astronomy, we looked for ways to identify multiple components of individual sources. To this effect, we design a convolutional neural network to differentiate between different morphology classes using sources from the Radio Galaxy Zoo (RGZ) citizen science project. In this first step, we focus on exploring the factors that affect the performance of such neural networks, such as the amount of training data, number and nature of layers, and the hyperparameters. We begin with a simple experiment in which we only differentiate between two extreme morphologies, using compact and multiple-component extended sources. We found that a three-convolutional layer architecture yielded very good results, achieving a classification accuracy of 97.4 per cent on a test data set. The same architecture was then tested on a four-class problem where we let the network classify sources into compact and three classes of extended sources, achieving a test accuracy of 93.5 per cent. The best-performing convolutional neural network set-up has been verified against RGZ Data Release 1 where a final test accuracy of 94.8 per cent was obtained, using both original and augmented images. The use of sigma clipping does not offer a significant benefit overall, except in cases with a small number of training images.

THE BOLOCAM GALACTIC PLANE SURVEY. II. CATALOG OF THE IMAGE DATA

International Nuclear Information System (INIS)

Rosolowsky, Erik; Dunham, Miranda K.; Evans, Neal J.; Harvey, Paul; Ginsburg, Adam; Bally, John; Battersby, Cara; Glenn, Jason; Stringfellow, Guy S.; Bradley, E. Todd; Aguirre, James; Cyganowski, Claudia; Dowell, Darren; Drosback, Meredith; Walawender, Josh; Williams, Jonathan P.

2010-01-01

We present a catalog of 8358 sources extracted from images produced by the Bolocam Galactic Plane Survey (BGPS). The BGPS is a survey of the millimeter dust continuum emission from the northern Galactic plane. The catalog sources are extracted using a custom algorithm, Bolocat, which was designed specifically to identify and characterize objects in the large-area maps generated from the Bolocam instrument. The catalog products are designed to facilitate follow-up observations of these relatively unstudied objects. The catalog is 98% complete from 0.4 Jy to 60 Jy over all object sizes for which the survey is sensitive ( -2.4±0.1 and that the mean Galactic latitude for sources is significantly below the midplane: (b) = (-0. 0 095 ± 0. 0 001).

Effects of thermal plasma on self-absorbed synchrotron sources in active galactic nuclei

International Nuclear Information System (INIS)

De Kool, M.; Begelman, M.C.

1989-01-01

The observable effects of a thermal background plasma in a self-absorbed synchrotron source are reviewed, in the context of a model for the central engine of an active galactic nucleus (AGN). Considering the effects of free-free absorption and emission, Thomson and Compton scattering, and spatial stratification, it is found that the observations set an upper limit on the thermal electron scattering optical depth in the central synchrotron-emitting region of an AGN. The upper limit, tau(max) about 1, results mainly from the apparent absence of induced Compton scattering and inverse thermal Comptonization effects. The low value of tau(max) poses some problems for nonthermal models of the AGN continuum that can be partly resolved by assuming a thin disk or layer-like geometry for the source, with (h/R) less than about 0.01. A likely site for the synchrotron-producing region seems to be the surface of an accretion disk or torus. 20 refs

Observation of galactic gamma radiation

International Nuclear Information System (INIS)

Paul, J.A.

1982-09-01

A complete and deep survey of the galactic high-energy gamma radiation is now available, thanks to the gamma-ray telescopes on board of the SAS-2 and COS-B spacecrafts. A comparison of the COS-B gamma-ray survey with a fully sampled CO survey together with an Hsub(I) survey is used to show that a simple model, in which uniformly distributed cosmic rays interact with the interstellar gas, can account for almost all the gamma-ray emission observed in the first galactic quadrant. At medium galactic latitudes, it is shown that a relationship exists between the gamma radiation and the interstellar absorption derived from galaxy counts. Therefore gamma rays from the local galactic environment can be used as a valuable probe of the content and structure of the local interstellar medium. The large scale features of the local interstellar gas are revealed, in particular wide concentrations of nearby molecular hydrogen. On a smaller scale, the detection of numerous localized gamma-ray sources focuses the attention on some particular phases of clusters of young and massive stars where diffuse processes of gamma-ray emission may also be at work

Compact quasi-monoenergetic photon sources from laser-plasma accelerators for nuclear detection and characterization

Energy Technology Data Exchange (ETDEWEB)

Geddes, Cameron G.R., E-mail: cgrgeddes@lbl.gov; Rykovanov, Sergey; Matlis, Nicholas H.; Steinke, Sven; Vay, Jean-Luc; Esarey, Eric H.; Ludewigt, Bernhard; Nakamura, Kei; Quiter, Brian J.; Schroeder, Carl B.; Toth, Csaba; Leemans, Wim P.

2015-05-01

Near-monoenergetic photon sources at MeV energies offer improved sensitivity at greatly reduced dose for active interrogation, and new capabilities in treaty verification, nondestructive assay of spent nuclear fuel and emergency response. Thomson (also referred to as Compton) scattering sources are an established method to produce appropriate photon beams. Applications are however restricted by the size of the required high-energy electron linac, scattering (photon production) system, and shielding for disposal of the high energy electron beam. Laser-plasma accelerators (LPAs) produce GeV electron beams in centimeters, using the plasma wave driven by the radiation pressure of an intense laser. Recent LPA experiments are presented which have greatly improved beam quality and efficiency, rendering them appropriate for compact high-quality photon sources based on Thomson scattering. Designs for MeV photon sources utilizing the unique properties of LPAs are presented. It is shown that control of the scattering laser, including plasma guiding, can increase photon production efficiency. This reduces scattering laser size and/or electron beam current requirements to scale compatible with the LPA. Lastly, the plasma structure can decelerate the electron beam after photon production, reducing the size of shielding required for beam disposal. Together, these techniques provide a path to a compact photon source system.

Compact sources for eyesafe illumination

Science.gov (United States)

Baranova, Nadia; Pu, Rui; Stebbins, Kenneth; Bystryak, Ilya; Rayno, Michael; Ezzo, Kevin; DePriest, Christopher

2018-02-01

Q-peak has demonstrated a compact, pulsed eyesafe laser architecture operating with >10 mJ pulse energies at repetition rates as high as 160 Hz. The design leverages an end-pumped solid-state laser geometry to produce adequate eyesafe beam quality (M2˜4), while also providing a path toward higher-density laser architectures for pulsed eyesafe applications. The baseline discussed in this paper has shown a unique capability for high-pulse repetition rates in a compact package, and offers additional potential for power scaling based on birefringence compensation. The laser consists of an actively Q-switched oscillator cavity producing pulse widths designed to fit within a volume of 3760 cm3. We will discuss details of the optical system design, modeled thermal effects and stress-induced birefringence, as well as experimental advantages of the end-pumped laser geometry, along with proposed paths to higher eyesafe pulse energies.

XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Galactic X-Ray Sources

Science.gov (United States)

Luo, Yang; Fang, Taotao; Ma, Renyi

2018-04-01

The detection of highly ionized metal absorption lines in the X-ray spectra of the Galactic X-ray binaries (XRBs) implies the distribution of hot gas along the sightline toward the background sources. However, the origin of this hot gas is still unclear: it can arise in the hot interstellar medium (ISM), or is intrinsic to the XRBs. In this paper, we present an XMM-Newton survey of the O VII absorption lines in the spectra of Galactic XRBs. A total of 33 XRBs were selected, with 29 low-mass XRBs and 4 high-mass XRBs. At a more than 3σ threshold, O VII absorption line was detected in 16 targets, among which 4 were newly discovered in this work. The average line equivalent width is centered around ∼20 mÅ. Additionally, we do not find strong correlations between the O VII EWs and the Galactic neutral absorption N H, the Galactic coordinates, or the distance of background targets. Such non-correlation may suggest contamination of the circumstellar material, or a lack of constraints on the line Doppler-b parameter. We also find that regardless of the direction of the XRBs, the O VII absorption lines are always detected when the flux of the background XRBs reaches a certain level, suggesting a uniform distribution of this hot gas. We estimate a ratio of 0.004–0.4 between the hot and neutral phases of the ISM. This is the second paper in the series following Fang et al. (2015), in which we focused on the local O VII absorption lines detected in the background AGN spectra. Detailed modeling of the hot ISM distribution will be investigated in a future paper.

Compact stellar X-ray sources

NARCIS (Netherlands)

Lewin, W.H.G.; van der Klis, M.

2006-01-01

X-ray astronomy is the prime available window on astrophysical compact objects: black holes, neutron stars and white dwarfs. In the last ten years new observational opportunities have led to an explosion of knowledge in this field. This book provides a comprehensive overview of the astrophysics of

An Active Black Hole in a Compact Dwarf

Science.gov (United States)

Kohler, Susanna

2016-05-01

A new type of galaxy has just been added to the galaxy zoo: a small, compact, and old elliptical galaxy that shows signs of a monster black hole actively accreting material in its center. What can this unusual discovery tell us about how compact elliptical galaxies form?A New Galactic BeastCompact elliptical galaxies are an extremely rare early-type dwarf galaxy. Consistent with their name, compact ellipticals are small, very compact collections of ancient stars; these galaxies exhibit a high surface brightness and arent actively forming stars.Optical view of the ancient compact elliptical galaxy SDSS J085431.18+173730.5 (center of image) in an SDSS color composite image. [Adapted from Paudel et al. 2016]Most compact ellipticals are found in dense environments, particularly around massive galaxies. This has led astronomers to believe that compact ellipticals might form via the tidal stripping of a once-large galaxy in interactions with another, massive galaxy. In this model, once the original galaxys outer layers are stripped away, the compact inner bulge component would be left behind as a compact elliptical galaxy. Recent discoveries of a few isolated compact ellipticals, however, have strained this model.Now a new galaxy has been found to confuse our classification schemes: the first-ever compact elliptical to also display signs of an active galactic nucleus. Led by Sanjaya Paudel (Korea Astronomy and Space Science Institute), a team of scientists discovered SDSS J085431.18+173730.5 serendipitously in Sloan Digital Sky Survey data. The team used SDSS images and spectroscopy in combination with data from the Canada-France-Hawaii Telescope to learn more about this unique galaxy.Puzzling CharacteristicsSDSS J085431.18+173730.5 presents an interesting conundrum. Ancient compact ellipticals are supposed to be devoid of gas, with no fuel left to trigger nuclear activity. Yet SDSS J085431.18+173730.5 clearly shows the emission lines that indicate active accretion onto

Study of X-ray and gamma ray sources observed by the SIGNE (Prognoz 6 Satellite) experiment in the regions of the galactic center and anticenter

International Nuclear Information System (INIS)

Violes, F.

1981-12-01

Characteristics of the SIGNE II MP 6 experiment are reported and procedures to obtain the fluxes detected from all the sources are described. We next present deconvolution method used to isolate the galactic center sources. In the last chapter we present and discuss the photon spectra of the sources observed by the SIGNE II MP 6 experiment [fr

Recent findings about the galactic gamma-ray sky by MAGIC

Energy Technology Data Exchange (ETDEWEB)

Strzys, Marcel C. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Collaboration: MAGIC-Collaboration

2015-07-01

The TeV sky currently consists of around 150 sources, about half of them situated within our galaxy. This group comprises various types of cosmic accelerators such as supernova remnants, pulsars, pulsar wind nebula, and binaries. From what we have observed in gamma rays so far, these sources can accelerate particles up to several hundred TeV. In this talk I will present recent results from the observation of galactic gamma-ray sources by MAGIC. This includes, among others, latest findings about the brightest, galactic gamma-ray source in the sky, the Crab nebula, results about one of the rare binary systems at TeV energies, insights into a not yet identified enigmatic source, and the discovery of the, so far, faintest PWN.

Discovery of a GeV Blazar Shining Through the Galactic Plane

Energy Technology Data Exchange (ETDEWEB)

Vandenbroucke, J.; Buehler, R.; Ajello, M.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Bellini, A.; /Padua U., Astron. Dept. /Baltimore, Space Telescope Sci.; Bolte, M.; /UC, Santa Cruz; Cheung, C.C.; /Naval Research Lab, Wash., D.C. /NAS, Washington, D.C.; Civano, F.; /Smithsonian Astrophys. Observ.; Donato, D.; /NASA, Goddard; Fuhrmann, L.; /Bonn, Max Planck Inst., Radioastron.; Funk, S.; Healey, S.E.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Hill, A.B.; /Joseph Fourier U.; Knigge, C.; /Southampton U.; Madejski, G.M.; Romani, R.W.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Santander-Garcia, M.; /IAC, La Laguna /Isaac Newton Group /Laguna U., Tenerife; Shaw, M.S.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC; Steeghs, D.; /Warwick U.; Torres, M.A.P.; /Smithsonian Astrophys. Observ.; Van Etten, A.; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Texas U., Astron. Dept.

2011-08-11

The Fermi Large Area Telescope (LAT) discovered a new gamma-ray source near the Galactic plane, Fermi J0109+6134, when it flared brightly in 2010 February. The low Galactic latitude (b = -1.2{sup o}) indicated that the source could be located within the Galaxy, which motivated rapid multi-wavelength follow-up including radio, optical, and X-ray observations. We report the results of analyzing all 19 months of LAT data for the source, and of X-ray observations with both Swift and the Chandra X-ray Observatory. We determined the source redshift, z = 0.783, using a Keck LRIS observation. Finally, we compiled a broadband spectral energy distribution (SED) from both historical and new observations contemporaneous with the 2010 February flare. The redshift, SED, optical line width, X-ray obsorption, and multi-band variability indicate that this new Gev source is a blazar seen through the Galactic plane. Because several of the optical emission lines have equivalent width > 5 {angstrom}, this blazar belongs in the flat-spectrum radio quasar category.

Galactic structure

International Nuclear Information System (INIS)

1989-01-01

The occurrence of hot, apparently normal, massive stars far from the galactic plane has been a major puzzle in an understanding of galactic structure and evolution. Such stars have been discovered and studied at the South African Astronomical Observatory (SAAO) over a number of years. During 1989 further evidence has been obtained indicating that these stars are normal, massive objects. Other studies of galactic structure conducted by the SAAO have included research on: the central bulge region of our galaxy; populations of M giants in the galaxy; a faint blue object survey; a survey of the galactic plane for distant Cepheid variables; interstellar reddening, and K-type dwarfs as tracers for the gravitational force perpendicular to the galactic plane. 1 fig

Interplanetary scintillation observations of an unbiased sample of 90 Ooty occultation radio sources at 326.5 MHz

International Nuclear Information System (INIS)

Banhatti, D.G.; Ananthakrishnan, S.

1989-01-01

We present 327-MHz interplanetary scintillation (IPS) observations of an unbiased sample of 90 extragalactic radio sources selected from the ninth Ooty lunar occultation list. The sources are brighter than 0.75 Jy at 327 MHz and lie outside the galactic plane. We derive values, the fraction of scintillating flux density, and the equivalent Gaussian diameter for the scintillating structure. Various correlations are found between the observed parameters. In particular, the scintillating component weakens and broadens with increasing largest angular size, and stronger scintillators have more compact scintillating components. (author)

Two-step design method for highly compact three-dimensional freeform optical system for LED surface light source.

Science.gov (United States)

Mao, Xianglong; Li, Hongtao; Han, Yanjun; Luo, Yi

2014-10-20

Designing an illumination system for a surface light source with a strict compactness requirement is quite challenging, especially for the general three-dimensional (3D) case. In accordance with the two key features of an expected illumination distribution, i.e., a well-controlled boundary and a precise illumination pattern, a two-step design method is proposed in this paper for highly compact 3D freeform illumination systems. In the first step, a target shape scaling strategy is combined with an iterative feedback modification algorithm to generate an optimized freeform optical system with a well-controlled boundary of the target distribution. In the second step, a set of selected radii of the system obtained in the first step are optimized to further improve the illuminating quality within the target region. The method is quite flexible and effective to design highly compact optical systems with almost no restriction on the shape of the desired target field. As examples, three highly compact freeform lenses with ratio of center height h of the lens and the maximum dimension D of the source ≤ 2.5:1 are designed for LED surface light sources to form a uniform illumination distribution on a rectangular, a cross-shaped and a complex cross pierced target plane respectively. High light control efficiency of η > 0.7 as well as low relative standard illumination deviation of RSD < 0.07 is obtained simultaneously for all the three design examples.

Theoretical galactic cosmic ray electron spectrum obtained for sources of varying geometry; Spectre theorique des electrons du rayonnement cosmique dans la galaxie obtenu pour des sources a geometrie variable

Energy Technology Data Exchange (ETDEWEB)

Cohen, M E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

Jokipii and Meyer have recently obtained an electron density energy spectrum of the cosmic rays, originating in the Galaxy, using integral solutions of the steady state transfer equations, by considering a circular cylindric galactic disc as source and approximating the resulting fourth order integral. In this report, we present general results, obtained by using an arbitrary circular cylindric source, without restricting ourselves to the galactic disc. The integrals are treated exactly. The conclusions of Jokipii and Meyer form special cases of these results. We also obtain an exponential energy variation which, at the moment, is not observed experimentally. The second part of this work deals with more complicated, but perhaps more realistic models of elliptic cylindric and ellipsoidal galactic disc sources. One may also note that a very large source concentrated in a very small region gives a spectrum not unlike that for a small source distributed throughout a large volume. Finally, it may be remarked that the model adopted is much less restrictive than the artificial conception of 'leakage time' followed by other workers. (author) [French] Jokipii et Meyer ont dernierement obtenu un spectre d'energie pour les electrons galactiques dans le rayonnement cosmique, en utilisant les solutions des equations de transfert, a l'etat stationnaire, ces dernieres etant sous forme d'integrales, en prenant une source completement diffusee dans le disque galactique, celui-ci etant hypothetiquement choisi comme circulaire et cylindrique et en faisant une approximation sur l'integrale du quatrieme degre. Dans ce rapport, nous presentons des resultats generaux obtenus en faisant appel a une source, diffusee dans un cylindre circulaire, arbitrairement choisi, c'est-a-dire sans nous restreindre au disque galactique comme source. Les integrales sont traitees d'une maniere exacte. Les conclusions de Jokipii et Meyer constituent des cas speciaux des resultats precedents. Nous obtenons

A compact soft X-ray microscope using an electrode-less Z-pinch source

Science.gov (United States)

Horne, S. F.; Silterra, J.; Holber, W.

2009-09-01

Soft X-rays (medical interest both for imaging and microdosimetry applications. X-ray sources at this low energy present a technological challenge. Synchrotrons, while very powerful and flexible, are enormously expensive national research facilities. Conventional X-ray sources based on electron bombardment can be compact and inexpensive, but low x-ray production efficiencies at low electron energies restrict this approach to very low power applications. Laser-based sources tend to be expensive and unreliable. Energetiq Technology, Inc. (Woburn, MA, USA) markets a 92 eV, 10W(2pi sr) electrode-less Z-pinch source developed for advanced semiconductor lithography. A modified version of this commercial product has produced 400 mW at 430 eV (2pi sr), appropriate for water window soft X-ray microscopy. The US NIH has funded Energetiq to design and construct a demonstration microscope using this source, coupled to a condenser optic, as the illumination system. The design of the condenser optic matches the unique characteristics of the source to the illumination requirements of the microscope, which is otherwise a conventional design. A separate program is underway to develop a microbeam system, in conjunction with the RARAF facility at Columbia University, NY, USA. The objective is to develop a focused, sub-micron beam capable of delivering > 1 Gy/second to the nucleus of a living cell. While most facilities of this type are coupled to a large and expensive particle accelerator, the Z-pinch X-ray source enables a compact, stand-alone design suitable to a small laboratory. The major technical issues in this system involve development of suitable focusing X-ray optics. Current status of these programs will be reported. (Supported by NIH grants 5R44RR022488-03 and 5R44RR023753-03)

The Atacama Cosmology Telescope: Dusty Star-Forming Galaxies and Active Galactic Nuclei in the Southern Survey

Science.gov (United States)

Marsden, Danica; Gralla, Megan; Marriage, Tobias A.; Switzer, Eric R.; Partridge, Bruce; Massardi, Marcella; Morales, Gustavo; Addison, Graeme; Bond, J. Richard; Crighton, Devin;

Prospects for compact high-intensity laser synchrotron x-ray and gamma sources

International Nuclear Information System (INIS)

Pogorelsky, I.V.

1996-11-01

A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high-brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power CO 2 laser may be used as prototype LSS brick stones. In a feasible demonstration experiment, 10-GW, 100-ps CO 2 laser beam will be brought to a head-on collision with a 10-ps, 0.5-nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 angstrom) x-rays of 10-ps pulse duration, with a flux of ∼ 10 19 photons/sec, will be produced via linear Compton backscattering. The x-ray spectrum is tunable proportionally to the e-beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 10 22 photons/sec level, after the ongoing ATF CO 2 laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact ''table-top'' LSS of monochromatic gamma radiation may become feasible

Prospects for compact high-intensity laser synchrotron x-ray and gamma sources

International Nuclear Information System (INIS)

Pogorelsky, I.V.

1997-01-01

A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high- brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high- brightness electron beam and the high-power C0 2 laser may be used as prototype LSS brick stones. In a feasible demonstration experiment, 10 GW, 100 ps C0 2 laser beam will be brought to a head-on collision with a 10 ps, 0.5 nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 A) x-rays of 10-ps pulse duration, with a flux of ∼10 19 photons/sec, will be produced via linear Compton backscattering. The x-ray spectra is tunable proportionally to the e- beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 10 22 photon/sec level, after the ongoing ATF C0 2 laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact ''table- top'' LSS of monochromatic gamma radiation may become feasible

Compact laser-produced plasma EUV sources for processing polymers and nanoimaging

International Nuclear Information System (INIS)

Fiedorowicz, H.; Bartnik, A.; Jarocki, R.; Kostecki, J.; Szczurek, M.; Wachulak, P.

2010-01-01

Complete text of publication follows. Extreme ultraviolet (EUV) can be produced form a high-temperature plasma generated by interaction of high power laser pulses with matter. Laser plasma EUV sources are considered to be used in various applications in physics, material science, biomedicine, and technology. In the paper new compact laser plasma EUV sources developed for processing polymers and imaging are presented. The sources are based on a gas puff target formed by pulsed injection of a small amount of gas under high-pressure into a laser focus region. The use of the gas puff target instead of a solid target allows for efficient generation of EUV radiation without debris production. The compact laser plasma EUV source based on a gas puff target was developed for metrology applications. The EUV source developed for processing polymers is equipped with a grazing incidence axisymmetrical ellipsoidal mirror to focus EUV radiation in the relatively broad spectral range with the strong maximum near 10 nm. The size of the focal spot is about 1.3 mm in diameter with the maximum fluence up to 70 mJ/cm 2 . EUV radiation in the wavelength range of about 5 to 50 nm is produced by irradiation of xenon or krypton gas puff target with a Nd:YAG laser operating at 10 Hz and delivering 4 ns pulses of energy up to 0.8 J per pulse. The experiments on EUV irradiation of various polymers have been performed. Modification of polymer surfaces was achieved, primarily due to direct photo-etching with EUV photons and formation of micro- and nanostructures onto the surface. The mechanism of the interaction is similar to the UV laser ablation where energetic photons cause chemical bonds of the polymer chain to be broken. However, because of very low penetration depth of EUV radiation, the interaction region is limited to a very thin surface layer (<100 nm). This makes it possible to avoid degradation of bulk material caused by deeply penetrating UV radiation. The results of the studies

THE GALFA-H I COMPACT CLOUD CATALOG

Energy Technology Data Exchange (ETDEWEB)

Saul, Destry R.; Peek, J. E. G.; Grcevich, J.; Putman, M. E.; Brown, A. R. H.; Hamden, E. T. [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Douglas, K. A. [Physics and Astronomy, University of Calgary/Dominion Radio Astrophysical Observatory, P.O. Box 248, Penticton, BC V2A 6J9 (Canada); Korpela, E. J. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Stanimirovic, S.; Lee, M.; Burkhart, B.; Pingel, N. M. [Department of Astronomy, University of Wisconsin, Madison, 475 N Charter St, Madison, WI 53703 (United States); Heiles, C. [Radio Astronomy Lab, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); Gibson, S. J. [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY 42101 (United States); Begum, A. [Indian Institute of Science Education and Research, ITI Campus (Gas Rahat) Building, Govindpura, Bhopal-23 (India); Tonnesen, S. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2012-10-10

We present a catalog of 1964 isolated, compact neutral hydrogen clouds from the Galactic Arecibo L-Band Feed Array Survey Data Release One. The clouds were identified by a custom machine-vision algorithm utilizing the difference of Gaussian kernels to search for clouds smaller than 20'. The clouds have velocities typically between |V{sub LSR}| =20 and 400 km s{sup -1}, line widths of 2.5-35 km s{sup -1}, and column densities ranging from 1 to 35 Multiplication-Sign 10{sup 18} cm{sup -2}. The distances to the clouds in this catalog may cover several orders of magnitude, so the masses may range from less than a solar mass for clouds within the Galactic disk, to greater than 10{sup 4} M{sub Sun} for high-velocity clouds (HVCs) at the tip of the Magellanic Stream. To search for trends, we separate the catalog into five populations based on position, velocity, and line width: HVCs; galaxy candidates; cold low-velocity clouds (LVCs); warm, low positive-velocity clouds in the third Galactic quadrant; and the remaining warm LVCs. The observed HVCs are found to be associated with previously identified HVC complexes. We do not observe a large population of isolated clouds at high velocities as some models predict. We see evidence for distinct histories at low velocities in detecting populations of clouds corotating with the Galactic disk and a set of clouds that is not corotating.

A Green Bank Telescope Survey of Large Galactic H II Regions

Science.gov (United States)

Anderson, L. D.; Armentrout, W. P.; Luisi, Matteo; Bania, T. M.; Balser, Dana S.; Wenger, Trey V.

2018-02-01

As part of our ongoing H II Region Discovery Survey (HRDS), we report the Green Bank Telescope detection of 148 new angularly large Galactic H II regions in radio recombination line (RRL) emission. Our targets are located at a declination of δ > -45^\\circ , which corresponds to 266^\\circ > {\\ell }> -20^\\circ at b=0^\\circ . All sources were selected from the Wide-field Infrared Survey Explorer Catalog of Galactic H II Regions, and have infrared angular diameters ≥slant 260\\prime\\prime . The Galactic distribution of these “large” H II regions is similar to that of the previously known sample of Galactic H II regions. The large H II region RRL line width and peak line intensity distributions are skewed toward lower values, compared with that of previous HRDS surveys. We discover seven sources with extremely narrow RRLs 100 {pc}, making them some of the physically largest known H II regions in the Galaxy. This survey completes the HRDS H II region census in the Northern sky, where we have discovered 887 H II regions and more than doubled the size of the previously known census of Galactic H II regions.

A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

NARCIS (Netherlands)

Banks, T.I.; Freedman, S.J.; Wallig, J.; Ybarrolaza, N.; Gando, A.; Gando, Y.; Ikeda, H.; Inoue, K.; Kishimoto, Y.; Koga, M.; Mitsui, T.; Nakamura, K.; Shimizu, I.; Shirai, J.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B.D.; Yoshida, H.; Yoshida, S.; Kozlov, A.; Grant, C.; Keefer, G.; Piepke, A.; Bloxham, T.; Fujikawa, B.K.; Han, K.; Ichimura, K.; Murayama, H.; O'Donnell, T.; Steiner, H.M.; Winslow, L.A.; Dwyer, D.A.; McKeown, R.D.; Zhang, C.; Berger, B.E.; Lane, C.E.; Maricic, J.; Miletic, T.; Batygov, M.; Learned, J.G.; Matsuno, S.; Sakai, M.; Horton-Smith, G.A.; Downum, K.E.; Gratta, G.; Efremenko, Y.; Perevozchikov, O.; Karwowski, H.J.; Markoff, D.M.; Tornow, W.; Heeger, K.M.; Detwiler, J.A.; Enomoto, S.; Decowski, M.P.

2015-01-01

We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an

Source-to-accelerator quadrupole matching section for a compact linear accelerator

Science.gov (United States)

Seidl, P. A.; Persaud, A.; Ghiorso, W.; Ji, Q.; Waldron, W. L.; Lal, A.; Vinayakumar, K. B.; Schenkel, T.

2018-05-01

Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

Galactic radio astronomy

CERN Document Server

Sofue, Yoshiaki

2017-01-01

This book is a concise primer on galactic radio astronomy for undergraduate and graduate students, and provides wide coverage of galactic astronomy and astrophysics such as the physics of interstellar matter and the dynamics and structure of the Milky Way Galaxy and galaxies. Radio astronomy and its technological development have led to significant progress in galactic astronomy and contributed to understanding interstellar matter and galactic structures. The book begins with the fundamental physics of radio-wave radiation, i.e., black body radiation, thermal emission, synchrotron radiation, and HI and molecular line emissions. The author then gives overviews of ingredients of galactic physics, including interstellar matter such as the neutral (HI), molecular hydrogen, and ionized gases, as well as magnetic fields in galaxies. In addition, more advanced topics relevant to the Galaxy and galaxies are also contained here: star formation, supernova remnants, the Galactic Center and black holes, galactic dynamics...

Transition from galactic to extra-galactic cosmic rays

International Nuclear Information System (INIS)

Aloisio, Roberto

2006-01-01

In this paper we review the main features of the observed Cosmic Rays spectrum in the energy range 10 17 eV to 10 20 eV. We present a theoretical model that explains the main observed features of the spectrum, namely the second Knee and Dip, and implies a transition from Galactic to Extra-Galactic cosmic rays at energy E ≅ 10 18 eV, with a proton dominated Extra-Galactic spectrum

Model Compaction Equation

African Journals Online (AJOL)

The currently proposed model compaction equation was derived from data sourced from the. Niger Delta and it relates porosity to depth for sandstones under hydrostatic pressure condition. The equation is useful in predicting porosity and compaction trend in hydrostatic sands of the. Niger Delta. GEOLOGICAL SETTING OF ...

Galactic water vapor emission: further observations of variability.

Science.gov (United States)

Knowles, S H; Mayer, C H; Sullivan, W T; Cheung, A C

1969-10-10

Recent observations of the 1.35-centimeter line emission of water vapor from galactic sources show short-term variability in the spectra of several sources. Two additional sources, Cygnus 1 and NGC 6334N, have been observed, and the spectra of W49 and VY Canis Majoris were measured over a wider range of radial velocity.

Does the Galactic Bulge Have Fewer Planets?

Science.gov (United States)

Kohler, Susanna

2016-12-01

The Milky Ways dense central bulge is a very different environment than the surrounding galactic disk in which we live. Do the differences affect the ability of planets to form in the bulge?Exploring Galactic PlanetsSchematic illustrating how gravitational microlensing by an extrasolar planet works. [NASA]Planet formation is a complex process with many aspects that we dont yet understand. Do environmental properties like host star metallicity, the density of nearby stars, or the intensity of the ambient radiation field affect the ability of planets to form? To answer these questions, we will ultimately need to search for planets around stars in a large variety of different environments in our galaxy.One way to detect recently formed, distant planets is by gravitational microlensing. In this process, light from a distant source star is bent by a lens star that is briefly located between us and the source. As the Earth moves, this momentary alignment causes a blip in the sources light curve that we can detect and planets hosted by the lens star can cause an additional observable bump.Artists impression of the Milky Way galaxy. The central bulge is much denserthan the surroundingdisk. [ESO/NASA/JPL-Caltech/M. Kornmesser/R. Hurt]Relative AbundancesMost source stars reside in the galactic bulge, so microlensing events can probe planetary systems at any distance between the Earth and the galactic bulge. This means that planet detections from microlensing could potentially be used to measure the relative abundances of exoplanets in different parts of our galaxy.A team of scientists led by Matthew Penny, a Sagan postdoctoral fellow at Ohio State University, set out to do just that. The group considered a sample of 31 exoplanetary systems detected by microlensing and asked the following question: are the planet abundances in the galactic bulge and the galactic disk the same?A Paucity of PlanetsTo answer this question, Penny and collaborators derived the expected

Measurement of the abundance of stellar mass compact objects in the galactic halo by detecting micro-lenses in the Large Magellanic Cloud; Mesure de l'abondance des astres sombres de masse stellaire dans le halo galactique par la recherche de phenomenes de microlentilles vers les nuages de magellan

Energy Technology Data Exchange (ETDEWEB)

Lasserre, Th

2000-05-09

Many experimental and theoretical results lead to the conclusion that at least 80 percent of the mass of our Galaxy is dark. Part of this so-called dark matter could be in the form of stellar mass compact objects, called MACHOS; these could be detected using the gravitational microlensing effect. The first generation experiments EROS1 and MACHO have strongly constrained the galactic abundance of objects lighter than 0.01 solar mass to less than 10 percent of the total mass. In parallel, the observation by the MACHO group of massive candidates (half the Sun's mass), numerous enough to constitute 50 percent of galactic dark matter, was a further motivation for the EROS group to extend this search to stellar mass objects in a second phase, EROS2. The present work deals with the analysis of 25 million stellar light curves in the Large Magellanic Cloud, observed for three years in order to extract the rare microlensing candidates and to measure the galactic halo mass fraction in the form of compact objects. After recalling the motivations of this search and the theoretical context, I describe the EROS2 experiment. The observational strategy and the photometric reduction procedures needed to deal with the 1.2 To of data are then presented. A new method to detect micro-lenses is detailed, as well as a discussion of background light curves, poorly known. We do not find enough microlensing candidates to explain the galactic rotation curve; this confirms, and improve on previous EROS1 and EROS2 results. Combining all results from EROS allows to exclude that MACHOS with a mass between 10 e-7 and 10 solar mass are important constituents of the galactic halo. This statement agrees with recent results from the MACHO group, although our interpretations differ, namely on the topics of the location of the lenses, and of a possible contamination of the microlensing ample by background phenomena. (author)

THE 37 MONTH MAXI/GSC SOURCE CATALOG OF THE HIGH GALACTIC-LATITUDE SKY

Energy Technology Data Exchange (ETDEWEB)

Hiroi, Kazuo; Ueda, Yoshihiro; Hayashida, Masaaki; Shidatsu, Megumi; Sato, Ryosuke; Kawamuro, Taiki [Department of Astronomy, Kyoto University, Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Sugizaki, Mutsumi; Serino, Motoko; Matsuoka, Masaru; Mihara, Tatehiro [Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Nakahira, Satoshi; Tomida, Hiroshi; Ueno, Shiro [ISS Science Project Office, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan); Kawai, Nobuyuki; Morii, Mikio [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Nakajima, Motoki [School of Dentistry at Matsudo, Nihon University, 2-870-1 Sakaecho-nishi, Matsudo, Chiba 101-8308 (Japan); Negoro, Hitoshi [Department of Physics, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Sakamoto, Takanori [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258 (Japan); Tsuboi, Yohko [Department of Physics, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Tsunemi, Hiroshi, E-mail: hiroi@kusastro.kyoto-u.ac.jp [Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); and others

2013-08-15

We present a catalog of high Galactic-latitude (|b| > 10 Degree-Sign ) X-ray sources detected in the first 37 months of data of the Monitor of All-sky X-ray Image/Gas Slit Camera (MAXI/GSC). To achieve the best sensitivity, we develop a background model of the GSC that well reproduces the data based on the detailed on-board calibration. Source detection is performed through image fits with a Poisson likelihood algorithm. The catalog contains 500 objects detected with significances of s{sub D,4-10keV} {>=} 7 in the 4-10 keV band. The limiting sensitivity is Almost-Equal-To 7.5 Multiplication-Sign 10{sup -12} erg cm{sup -2} s{sup -1} ( Almost-Equal-To 0.6 mCrab) in the 4-10 keV band for 50% of the survey area, which is the highest ever achieved in an all-sky survey mission covering this energy band. We summarize the statistical properties of the catalog and results from cross matching with the Swift/BAT 70 month catalog, the meta-catalog of X-ray detected clusters of galaxies, and the MAXI/GSC 7 month catalog. Our catalog lists the source name (2MAXI), position and its error, detection significances and fluxes in the 4-10 keV and 3-4 keV bands, the hardness ratio, and the basic information of the likely counterpart available for 296 sources.

Monitoring the Galactic - Search for Hard X-Ray Transients

Science.gov (United States)

Marshall, Francis

Hard X-ray transients with fluxs from ~1 to ~30 mCrab are a common feature of the galactic plane with apparent concentrations in specific regions of the plane. Concentrations in the Scutum and Carina fields probably indicate an enhancement of Be X-ray binaries along the tangent direction of two spiral arms. The frequency of outbursts suggest that at any one time 1 or 2 transients are active in the Scutum field alone. We propose weekly scans of the galactic plane to understand this population of sources. The scans will also monitor about 50 already known sources with better spectral information than available with the ASM.

A new class of galactic discrete gamma ray sources: Chaotic winds of massive stars

Science.gov (United States)

Chen, Wan; White, Richard L.

1992-01-01

We propose a new class of galactic discrete gamma-ray sources, the chaotic, high mass-loss-rate winds from luminous early-type stars. Early-type stellar winds are highly unstable due to intrinsic line-driven instabilities, and so are permeated by numerous strong shocks. These shocks can accelerate a small fraction of thermal electrons and ions to relativistic energies via the first-order Fermi mechanism. A power-law-like photon spectrum extending from keV to above 10 MeV energies is produced by inverse Compton scattering of the extremely abundant stellar UV photons by the relativistic electrons. In addition, a typical pi(sup 0)-decay gamma-ray spectrum is generated by proton-ion interactions in the densest part of the winds.

Linking optical and infrared observations with gravitational wave sources through transient variability

International Nuclear Information System (INIS)

Stubbs, C W

2008-01-01

Optical and infrared observations have thus far detected more celestial cataclysms than have been seen in gravity waves (GW). This argues that we should search for gravity wave signatures that correspond to transient variables seen at optical wavelengths, at precisely known positions. There is an unknown time delay between the optical and gravitational transient, but knowing the source location precisely specifies the corresponding time delays across the gravitational antenna network as a function of the GW-to-optical arrival time difference. Optical searches should detect virtually all supernovae that are plausible gravitational radiation sources. The transient optical signature expected from merging compact objects is not as well understood, but there are good reasons to expect detectable transient optical/IR emission from most of these sources as well. The next generation of deep wide-field surveys (for example PanSTARRS and LSST) will be sensitive to subtle optical variability, but we need to fill the 'blind spots' that exist in the galactic plane, and for optically bright transient sources. In particular, a galactic plane variability survey at λ∼ 2 μm seems worthwhile. Science would benefit from closer coordination between the various optical survey projects and the gravity wave community

Development of a compact x-ray source via laser compton scattering at KEK-LUCX

International Nuclear Information System (INIS)

Sakaue, Kazuyuki; Washio, Masakazu; Aryshev, Alexander; Araki, Sakae; Urakawa, Junji; Terunuma, Nobuhiro; Fukuda, Masafumi; Miyoshi, Toshinobu; Takeda, Ayaki

2013-01-01

The compact X-ray source based on Laser-Compton scattering (LCS) has been developed at LUCX (Laser Undulator Compact X-ray source) facility in KEK. The multi-bunch high quality electron beam produced by a standing wave 3.6 cell RF Gun and accelerated by the followed S-band normal conducting 12 cells standing wave 'Booster' linear accelerator is scattered off the laser beam stored in the optical cavity. The 4-mirror planar optical cavity with finesse 335 is used. The MCP (Micro-Channer Plate) detector as well as SOI (Silicon-On-Insulator) pixel sensor was used for scattered X-ray detection. The SOI pixel sensor has been used for LCS X-ray detection for the first time and has demonstrated high spatial resolution and high SN ratio X-ray detection that in turn lead to clearest X-ray images achieved by LCS X-ray. We have also achieved generation of 6.38x10 6 ph./sec., which is more than 30 times larger LCS X-ray flux in comparison with our previous results. The complete details of LUCX LCS X-ray source, specifications of both electron and laser beams, and the results of LCS X-ray generation experiments are reported in this paper. (author)

Study and modeling of the most energetic Active Galactic Nuclei with the Fermi satellite

International Nuclear Information System (INIS)

Sanchez, D.

2010-06-01

The Fermi satellite was launched in June 2008. The onboard LAT detector is dedicated to the study of galactic and extra-galactic gamma sources with an energy comprised between 200 MeV and 300 GeV. 1451 sources have been detected in less than 11 months. This document is divided into 6 chapters: 1) gamma astronomy, 2) the Fermi satellite, 3) the active galactic nuclei (NAG), 4) the observation of several blazars (PKS-2155-304 and PG-1553+113) and its simulation, 5) the observation of PKS-2155-304 with both RXTE and Fermi, and 6) conclusion

A compact Compton backscatter X-ray source for mammography and coronary angiography

International Nuclear Information System (INIS)

Nguyen, D.C.; Kinross-Wright, J.M.; Weber, M.E.; Volz, S.K.; Gierman, S.M.; Hayes, K.; Vernon, W.; Goldstein, D.J.

1998-01-01

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objective is to generate a large flux of tunable, monochromatic x-rays for use in mammography and coronary angiography. The approach is based on Compton backscattering of an ultraviolet solid-state laser beam against the high-brightness 20-MeV electron beams from a compact linear accelerator. The direct Compton backscatter approach failed to produce a large flux of x-rays due to the low photon flux of the scattering solid-state laser. The authors have modified the design of a compact x-ray source to the new Compton backscattering geometry with use of a regenerative amplifier free-electron laser. They have successfully demonstrated the production of a large flux of infrared photons and a high-brightness electron beam focused in both dimensions for performing Compton backscattering in a regenerative amplifier geometry

New shielding material development for compact accelerator-driven neutron source

Directory of Open Access Journals (Sweden)

Guang Hu

2017-04-01

Full Text Available The Compact Accelerator-driven Neutron Source (CANS, especially the transportable neutron source is longing for high effectiveness shielding material. For this reason, new shielding material is researched in this investigation. The component of shielding material is designed and many samples are manufactured. Then the attenuation detection experiments were carried out. In the detections, the dead time of the detector appeases when the proton beam is too strong. To grasp the linear range and nonlinear range of the detector, two currents of proton are employed in Pb attenuation detections. The transmission ratio of new shielding material, polyethylene (PE, PE + Pb, BPE + Pb is detected under suitable current of proton. Since the results of experimental neutrons and γ-rays appear as together, the MCNP and PHITS simulations are applied to assisting the analysis. The new shielding material could reduce of the weight and volume compared with BPE + Pb and PE + Pb.

Frequent VLBI Monitoring on Parsec-Scales of 450+ Extragalactic FERMI Sources at 8 and 32 GHz

Science.gov (United States)

Jacobs, Christopher S.; Majid, W. A.; Romero-Wolf, A.; García-Mirí, C.; Horiuchi, S.; Snedeker, L. G.; Sotuela, I.

2012-10-01

Executive Summary: An existing Ka-band (32 GHz, 9mm) catalog of 450+ sources is being monitored every 6-10 weeks on Giga-lambda baselines. These observations are sensitive to parsec scale activity in the AGN cores providing unique tests of gamma ray emission models. Abstract: The Fermi Large Area Telescope (LAT) has now released the 2nd catalog of high-energy gamma-ray sources (2FGL) derived from the first 24 months of mission science data with 1873 sources detected and characterized in the 100 MeV to 100 GeV range. 1017 of 1873 sources at high Galactic latitude (abs(b) > 10 degrees) are associated statistically with active galactic nuclei (AGNs). Parsec-scale VLBI measurements play an important role in characterizing the nature of the candidate AGNs by providing crucial extra information to improve the probability of correct identification - VLBI filters out objects which do not host strong compact jets at parsec scale. We are carrying out regular VLBI monitoring of 450+ compact extragalactic sources using Deep Space Network (DSN) 34-meter antennas over intercontinental baselines simultaneously at 8 and 32 GHz. In addition to precision astrometric measurements of AGN compact cores used to maintain the JPL extragalactic reference frame, this program has the potential to provide regular simultaneous flux density measurements at 8 and 32 GHz with precision level of ~20%. By providing measurements on both East-West and North-South baselines with large antennas and Gbit/s recording capability, our program can probe sources down to a flux limit of 30 mJy (10-sigma), potentially increasing the sample to a fainter population of sources. In these regards, our program complements well existing northern and southern hemisphere VLBI monitoring programs, by providing flux measurements at 32 GHz, covering a fainter population sample, and by filling the gap for sources in the -20 to -45 degree declination range. Further, our program also provides additional flexibility for

The Advanced Gamma-ray Imaging System (AGIS): Galactic Astrophysics

Science.gov (United States)

Digel, Seth William; Funk, S.; Kaaret, P. E.; Tajima, H.; AGIS Collaboration

2010-03-01

The Advanced Gamma-ray Imaging System (AGIS), a concept for a next-generation atmospheric Cherenkov telescope array, would provide unprecedented sensitivity and resolution in the energy range >50 GeV, allowing great advances in the understanding of the populations and physics of sources of high-energy gamma rays in the Milky Way. Extrapolation based on the known source classes and the performance parameters for AGIS indicates that a survey of the Galactic plane with AGIS will reveal hundreds of TeV sources in exquisite detail, for population studies of a variety of source classes, and detailed studies of individual sources. AGIS will be able to study propagation effects on the cosmic rays produced by Galactic sources by detecting the diffuse glow from their interactions in dense interstellar gas. AGIS will complement and extend results now being obtained in the GeV range with the Fermi mission, by providing superior angular resolution and sensitivity to variability on short time scales, and of course by probing energies that Fermi cannot reach.

THE BOLOCAM GALACTIC PLANE SURVEY. VIII. A MID-INFRARED KINEMATIC DISTANCE DISCRIMINATION METHOD

Energy Technology Data Exchange (ETDEWEB)

Ellsworth-Bowers, Timothy P.; Glenn, Jason; Battersby, Cara; Ginsburg, Adam; Bally, John [CASA, University of Colorado, UCB 389, University of Colorado, Boulder, CO 80309 (United States); Rosolowsky, Erik [Department of Physics and Astronomy, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC V1V 1V7 (Canada); Mairs, Steven [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 1A1 (Canada); Evans, Neal J. II [Department of Astronomy, University of Texas, 1 University Station C1400, Austin, TX 78712 (United States); Shirley, Yancy L., E-mail: timothy.ellsworthbowers@colorado.edu [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

2013-06-10

We present a new distance estimation method for dust-continuum-identified molecular cloud clumps. Recent (sub-)millimeter Galactic plane surveys have cataloged tens of thousands of these objects, plausible precursors to stellar clusters, but detailed study of their physical properties requires robust distance determinations. We derive Bayesian distance probability density functions (DPDFs) for 770 objects from the Bolocam Galactic Plane Survey in the Galactic longitude range 7. Degree-Sign 5 {<=} l {<=} 65 Degree-Sign . The DPDF formalism is based on kinematic distances, and uses any number of external data sets to place prior distance probabilities to resolve the kinematic distance ambiguity (KDA) for objects in the inner Galaxy. We present here priors related to the mid-infrared absorption of dust in dense molecular regions and the distribution of molecular gas in the Galactic disk. By assuming a numerical model of Galactic mid-infrared emission and simple radiative transfer, we match the morphology of (sub-)millimeter thermal dust emission with mid-infrared absorption to compute a prior DPDF for distance discrimination. Selecting objects first from (sub-)millimeter source catalogs avoids a bias towards the darkest infrared dark clouds (IRDCs) and extends the range of heliocentric distance probed by mid-infrared extinction and includes lower-contrast sources. We derive well-constrained KDA resolutions for 618 molecular cloud clumps, with approximately 15% placed at or beyond the tangent distance. Objects with mid-infrared contrast sufficient to be cataloged as IRDCs are generally placed at the near kinematic distance. Distance comparisons with Galactic Ring Survey KDA resolutions yield a 92% agreement. A face-on view of the Milky Way using resolved distances reveals sections of the Sagittarius and Scutum-Centaurus Arms. This KDA-resolution method for large catalogs of sources through the combination of (sub-)millimeter and mid-infrared observations of molecular

Compact X-ray source based on Compton backscattering

CERN Document Server

Bulyak, E V; Zelinsky, A; Karnaukhov, I; Kononenko, S; Lapshin, V G; Mytsykov, A; Telegin, Yu P; Khodyachikh, A; Shcherbakov, A; Molodkin, V; Nemoshkalenko, V; Shpak, A

2002-01-01

The feasibility study of an intense X-ray source based on the interaction between the electron beam in a compact storage ring and the laser pulse accumulated in an optical resonator is carried out. We propose to reconstruct the 160 MeV electron storage ring N-100, which was shutdown several years ago. A new magnetic lattice will provide a transverse of electron beam size of approx 35 mu m at the point of electron beam-laser beam interaction. The proposed facility is to generate X-ray beams of intensity approx 2.6x10 sup 1 sup 4 s sup - sup 1 and spectral brightness approx 10 sup 1 sup 2 phot/0.1%bw/s/mm sup 2 /mrad sup 2 in the energy range from 10 keV up to 0.5 MeV. These X-ray beam parameters meet the requirements for most of technological and scientific applications. Besides, we plan to use the new facility for studying the laser cooling effect.

Compact X-ray source based on Compton backscattering

Energy Technology Data Exchange (ETDEWEB)

Bulyak, E.; Gladkikh, P.; Zelinsky, A. E-mail: zelinsky@kipt.kharkov.ua; Karnaukhov, I.; Kononenko, S.; Lapshin, V.; Mytsykov, A.; Telegin, Yu.; Khodyachikh, A.; Shcherbakov, A.; Molodkin, V.; Nemoshkalenko, V.; Shpak, A

2002-07-21

The feasibility study of an intense X-ray source based on the interaction between the electron beam in a compact storage ring and the laser pulse accumulated in an optical resonator is carried out. We propose to reconstruct the 160 MeV electron storage ring N-100, which was shutdown several years ago. A new magnetic lattice will provide a transverse of electron beam size of {approx}35 {mu}m at the point of electron beam-laser beam interaction. The proposed facility is to generate X-ray beams of intensity {approx}2.6x10{sup 14} s{sup -1} and spectral brightness {approx}10{sup 12} phot/0.1%bw/s/mm{sup 2}/mrad{sup 2} in the energy range from 10 keV up to 0.5 MeV. These X-ray beam parameters meet the requirements for most of technological and scientific applications. Besides, we plan to use the new facility for studying the laser cooling effect.

Compact X-ray source at STF (Super Conducting Accelerator Test Facility)

International Nuclear Information System (INIS)

Urakawa, J

2012-01-01

KEK-STF is a super conducting linear accelerator test facility for developing accelerator technologies for the ILC (International Linear Collider). We are supported in developing advanced accelerator technologies using STF by Japanese Ministry (MEXT) for Compact high brightness X-ray source development. Since we are required to demonstrate the generation of high brightness X-ray based on inverse Compton scattering using super conducting linear accelerator and laser storage cavity technologies by October of next year (2012), the design has been fixed and the installation of accelerator components is under way. The necessary technology developments and the planned experiment are explained.

Resolving the structure of the Galactic foreground using Herschel measurements and the Kriging technique

Science.gov (United States)

Pinter, S.; Bagoly, Z.; Balázs, L. G.; Horvath, I.; Racz, I. I.; Zahorecz, S.; Tóth, L. V.

2018-05-01

Investigating the distant extragalactic Universe requires a subtraction of the Galactic foreground. One of the major difficulties deriving the fine structure of the galactic foreground is the embedded foreground and background point sources appearing in the given fields. It is especially so in the infrared. We report our study subtracting point sources from Herschel images with Kriging, an interpolation method where the interpolated values are modelled by a Gaussian process governed by prior covariances. Using the Kriging method on Herschel multi-wavelength observations the structure of the Galactic foreground can be studied with much higher resolution than previously, leading to a better foreground subtraction at the end.

Compact sources as the origin of the soft gamma-ray emission of the Milky Way

DEFF Research Database (Denmark)

Lebrun, F.; Terrier, R.; Bazzano, A.

2004-01-01

The Milky Way is known to be an abundant source of gamma-ray photons(1), now determined to be mainly diffuse in nature and resulting from interstellar processes(2). In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did...... the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium(7). Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We...

THE ARECIBO METHANOL MASER GALACTIC PLANE SURVEY. III. DISTANCES AND LUMINOSITIES

International Nuclear Information System (INIS)

Pandian, J. D.; Menten, K. M.; Goldsmith, P. F.

2009-01-01

We derive kinematic distances to the 86 6.7 GHz methanol masers discovered in the Arecibo Methanol Maser Galactic Plane Survey. The systemic velocities of the sources were derived from 13 CO (J = 2-1), CS (J = 5-4), and NH 3 observations made with the ARO Submillimeter Telescope, the APEX telescope, and the Effelsberg 100 m telescope, respectively. Kinematic distance ambiguities were resolved using H I self-absorption with H I data from the VLA Galactic Plane Survey. We observe roughly three times as many sources at the far distance compared to the near distance. The vertical distribution of the sources has a scale height of ∼ 30 pc, and is much lower than that of the Galactic thin disk. We use the distances derived in this work to determine the luminosity function of 6.7 GHz maser emission. The luminosity function has a peak at approximately 10 -6 L sun . Assuming that this luminosity function applies, the methanol maser population in the Large Magellanic Cloud and M33 is at least 4 and 14 times smaller, respectively, than in our Galaxy.

Complex organic molecules in the Galactic Centre: the N-bearing family

Science.gov (United States)

Zeng, S.; Jiménez-Serra, I.; Rivilla, V. M.; Martín, S.; Martín-Pintado, J.; Requena-Torres, M. A.; Armijos-Abendaño, J.; Riquelme, D.; Aladro, R.

2018-05-01

We present an unbiased spectral line survey toward the Galactic Centre (GC) quiescent giant molecular cloud (QGMC), G+0.693 using the GBT and IRAM 30 telescopes. Our study highlights an extremely rich organic inventory of abundant amounts of nitrogen (N)-bearing species in a source without signatures of star formation. We report the detection of 17 N-bearing species in this source, of which 8 are complex organic molecules (COMs). A comparison of the derived abundances relative to H2 is made across various galactic and extragalactic environments. We conclude that the unique chemistry in this source is likely to be dominated by low-velocity shocks with X-rays/cosmic rays also playing an important role in the chemistry. Like previous findings obtained for O-bearing molecules, our results for N-bearing species suggest a more efficient hydrogenation of these species on dust grains in G+0.693 than in hot cores in the Galactic disk, as a consequence of the low dust temperatures coupled with energetic processing by X-ray/cosmic ray radiation in the GC.

Galactic dynamics

CERN Document Server

Binney, James

2008-01-01

Since it was first published in 1987, Galactic Dynamics has become the most widely used advanced textbook on the structure and dynamics of galaxies and one of the most cited references in astrophysics. Now, in this extensively revised and updated edition, James Binney and Scott Tremaine describe the dramatic recent advances in this subject, making Galactic Dynamics the most authoritative introduction to galactic astrophysics available to advanced undergraduate students, graduate students, and researchers. Every part of the book has been thoroughly overhauled, and many section

SMM detection of diffuse Galactic 511 keV annihilation radiation

Science.gov (United States)

Share, G. H.; Kinzer, R. L.; Kurfess, J. D.; Messina, D. C.; Purcell, W. R.

1988-01-01

Observations of the 511 keV annihilation line from the vicinity of the Galactic center from October to February for 1980/1981, 1981/1982, 1982/1983, 1984/1985, and 1985/1986 are presented. The measurements were made with the gamma-ray spectrometer on the SMM. The design of the instrument and some of its properties used in the analysis are described, and the methods used for accumulating, fitting, and analyzing the data are outlined. It is shown how the Galactic 511 keV line was separated from the intense and variable background observed in orbit. The SMM observations are compared with previous measurements of annihilation radiation from the Galactic center region, and the astrophysical implications are discussed. It is argued that most of the measurements made to date suggest the presence of an extended Galactic source of annihilation radiation.

An asymmetric distribution of positrons in the Galactic disk revealed by γ-rays

International Nuclear Information System (INIS)

Weidenspointner, G.; Skinner, G.; Jean, P.; Knoedlseder, J.; Von Ballmoos, P.; Bignami, G.; Weidenspointner, G.; Diehl, R.; Strong, A.; Weidenspointner, G.; Skinner, G.; Skinner, G.; Skinner, G.; Cordier, B.; Schanne, S.; Winkler, Ch.; Bignami, G.

2008-01-01

Gamma-ray line radiation at 511 keV is the signature of electron positron annihilation. Such radiation has been known for 30 years to come from the general direction of the Galactic Centre, but the origin of the positrons has remained a mystery. Stellar nucleosynthesis, accreting compact objects, and even the annihilation of exotic dark-matter particles have all been suggested. Here we report a distinct asymmetry in the 511 keV line emission coming from the inner Galactic disk (∼ 10-50 degrees from the Galactic Centre). This asymmetry resembles an asymmetry in the distribution of low mass X-ray binaries with strong emission at photon energies ≥20 keV ('hard' LMXBs), indicating that they may be the dominant origin of the positrons. Although it had long been suspected that electron-positron pair plasmas may exist in X-ray binaries, it was not evident that many of the positrons could escape to lose energy and ultimately annihilate with electrons in the interstellar medium and thus lead to the emission of a narrow 511 keV line. For these models, our result implies that up to a few times 10 41 positrons escape per second from a typical hard LMXB. Positron production at this level from hard LMXBs in the Galactic bulge would reduce (and possibly eliminate) the need for more exotic explanations, such as those involving dark matter. (authors)

An asymmetric distribution of positrons in the Galactic disk revealed by {gamma}-rays

Energy Technology Data Exchange (ETDEWEB)

Weidenspointner, G; Skinner, G; Jean, P; Knoedlseder, J; Von Ballmoos, P; Bignami, G [UPS, CNRS, Ctr Etud Spatiale Rayonnements, Toulouse 4, (France); Weidenspointner, G; Diehl, R; Strong, A [Max Planck Inst Extraterr Phys, D-85741 Garching, (Germany); Weidenspointner, G [MPI Halbleiterlab, D-81739 Munich, (Germany); Skinner, G [NASA, CRESST, Greenbelt, MD 20771 (United States); Skinner, G [NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 (United States); Skinner, G [Univ Maryland, Dept Astron, College Pk, MD 20742 (United States); Cordier, B; Schanne, S [CEA Saclay, DSM, DAPNIA, SAp, F-91191 Gif Sur Yvette, (France); Winkler, Ch [ESA, ESTEC, SCI SA, NL-2201 AZ Noordwijk, (Netherlands); Bignami, G [IUSS, I-27100 Pavia, (Italy)

2008-07-01

Gamma-ray line radiation at 511 keV is the signature of electron positron annihilation. Such radiation has been known for 30 years to come from the general direction of the Galactic Centre, but the origin of the positrons has remained a mystery. Stellar nucleosynthesis, accreting compact objects, and even the annihilation of exotic dark-matter particles have all been suggested. Here we report a distinct asymmetry in the 511 keV line emission coming from the inner Galactic disk ({approx} 10-50 degrees from the Galactic Centre). This asymmetry resembles an asymmetry in the distribution of low mass X-ray binaries with strong emission at photon energies {>=}20 keV ('hard' LMXBs), indicating that they may be the dominant origin of the positrons. Although it had long been suspected that electron-positron pair plasmas may exist in X-ray binaries, it was not evident that many of the positrons could escape to lose energy and ultimately annihilate with electrons in the interstellar medium and thus lead to the emission of a narrow 511 keV line. For these models, our result implies that up to a few times 10{sup 41} positrons escape per second from a typical hard LMXB. Positron production at this level from hard LMXBs in the Galactic bulge would reduce (and possibly eliminate) the need for more exotic explanations, such as those involving dark matter. (authors)

The Galactic magnetic fields

International Nuclear Information System (INIS)

Han Jinlin

2006-01-01

A good progress has been made on studies of Galactic magnetic fields in last 10 years. I describe what we want to know about the Galactic magnetic fields, and then review we current knowledge about magnetic fields in the Galactic disk, the Galactic halo and the field strengths. I also listed many unsolved problems on this area

Elusive active galactic nuclei

Science.gov (United States)

Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.

2003-10-01

A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.

X-RAY PROPERTIES OF THE NORTHERN GALACTIC CAP SOURCES IN THE 58 MONTH SWIFT/BAT CATALOG

International Nuclear Information System (INIS)

Vasudevan, Ranjan V.; Mushotzky, Richard F.; Shimizu, Thomas T.; Brandt, William N.; Schneider, Donald P.; Nousek, John; Winter, Lisa M.; Baumgartner, Wayne H.

2013-01-01

We present a detailed X-ray spectral analysis of the non-beamed, hard X-ray selected active galactic nuclei (AGNs) in the northern Galactic cap of the 58 month Swift Burst Alert Telescope (Swift/BAT) catalog, consisting of 100 AGNs with b > 50°. This sky area has excellent potential for further dedicated study due to a wide range of multi-wavelength data that are already available, and we propose it as a low-redshift analog to the 'deep field' observations of AGNs at higher redshifts (e.g., CDFN/S, COSMOS, Lockman Hole). We present distributions of luminosity, absorbing column density, and other key quantities for the catalog. We use a consistent approach to fit new and archival X-ray data gathered from XMM-Newton, Swift/XRT, ASCA, and Swift/BAT. We probe to deeper redshifts than the 9 month BAT catalog ((z) = 0.043 compared to (z) = 0.03 for the 9 month catalog), and uncover a broader absorbing column density distribution. The fraction of obscured (log N H ≥ 22) objects in the sample is ∼60%, and 43%-56% of the sample exhibits 'complex' 0.4-10 keV spectra. We present the properties of iron lines, soft excesses, and ionized absorbers for the subset of objects with sufficient signal-to-noise ratio. We reinforce previous determinations of the X-ray Baldwin (Iwasawa-Taniguchi) effect for iron Kα lines. We also identify two distinct populations of sources; one in which a soft excess is well-detected and another where the soft excess is undetected, suggesting that the process responsible for producing the soft excess is not at work in all AGNs. The fraction of Compton-thick sources (log N H > 24.15) in our sample is ∼9%. We find that 'hidden/buried AGNs' (which may have a geometrically thick torus or emaciated scattering regions) constitute ∼14% of our sample, including seven objects previously not identified as hidden. Compton reflection is found to be important in a large fraction of our sample using joint XMM-Newton+BAT fits ((R) = 2.7 ± 0.75), indicating

Design parameters for a 7.2 tesla bending magnet for a 1.5 GeV compact light source

International Nuclear Information System (INIS)

Green, M.A.; Madura, D.

1995-06-01

This report describes the design for a 7.2 tesla superconducting dipole magnet for a compact synchrotron light source. The proposed magnet is a Vobly type modified picture frame dipole that has the flux returned through unsaturated iron. In this magnet, The iron in the pole pieces is highly saturated, Separately powered coils around the pole pieces are used to direct the flux lines until the flux can be returned through the unsaturated iron. The proposed dipole will develop a uniform field over a region that is 80 mm high by 130 mm wide over a range of central induction from 0.4 T to almost 8 T. Each dipole for the compact light source will have a magnetic length of about 0.38 meters

New Galactic Candidate Luminous Blue Variables and Wolf-Rayet Stars

Science.gov (United States)

Stringfellow, Guy S.; Gvaramadze, Vasilii V.; Beletsky, Yuri; Kniazev, Alexei Y.

2012-04-01

We have undertaken a near-infrared spectral survey of stars associated with compact mid-IR shells recently revealed by the MIPSGAL (24 μm) and GLIMPSE (8 μm) Spitzer surveys, whose morphologies are typical of circumstellar shells produced by massive evolved stars. Through spectral similarity with known Luminous Blue Variable (LBV) and Wolf-Rayet (WR) stars, a large population of candidate LBVs (cLBVs) and a smaller number of new WR stars are being discovered. This significantly increases the Galactic cLBV population and confirms that nebulae are inherent to most (if not all) objects of this class.

Diffuse gamma-ray emission from self-confined cosmic rays around Galactic sources

Science.gov (United States)

D'Angelo, Marta; Morlino, Giovanni; Amato, Elena; Blasi, Pasquale

2018-02-01

The propagation of particles accelerated at supernova remnant shocks and escaping the parent remnants is likely to proceed in a strongly non-linear regime, due to the efficient self-generation of Alfvén waves excited through streaming instability near the sources. Depending on the amount of neutral hydrogen present in the regions around the sites of supernova explosions, cosmic rays may accumulate an appreciable grammage in the same regions and get self-confined for non-negligible times, which in turn results in an enhanced rate of production of secondaries. Here we calculate the contribution to the diffuse gamma-ray background due to the overlap along lines of sight of several of these extended haloes as due to pion production induced by self-confined cosmic rays. We find that if the density of neutrals is low, the haloes can account for a substantial fraction of the diffuse emission observed by Fermi-Large Area Telescope (LAT), depending on the orientation of the line of sight with respect to the direction of the Galactic Centre.

Design study of the compact ERL

International Nuclear Information System (INIS)

Hajima, Ryoichi; Nakamura, Norio; Sakanaka, Shogo; Kobayashi, Yukinori

2008-02-01

Energy-recovery linac (ERL) is a promising device for future X-ray light sources, which can produce coherent X-rays and femto-second X-ray pulses. In Japan, we have organized a collaboration team, consisting of the members of KEK, JAEA, ISSP and other laboratories, toward realization of future ERL light sources, and started R and D efforts to establish accelerator technologies relevant to the ERL light source. In order to demonstrate all the accelerator technologies working together, we have decided to build a small facility, the Compact ERL. This report presents a design study of the Compact ERL, which includes R and D issues for each accelerator component, studies on the beam dynamics, performance of the Compact ERL as a light source of THz and X-ray. (author)

Neutrino fluxes from the Galactic plane and the ANTARES limit

Directory of Open Access Journals (Sweden)

Fusco Luigi Antonio

2016-01-01

Full Text Available The existence of cosmic neutrinos has been reported by the IceCube Collaboration. Though this measurement is consistent with an isotropic neutrino flux, a sub-dominant galactic component coming from extended regions such as the Galactic Plane cannot be excluded. The ANTARES detector, located in the Mediterranean Sea, is currently the largest and longest operated under-water neutrino telescope; its effective area and good exposure to the Southern Sky allow to constrain an enhanced muon neutrino emission from extended sources such as the Galactic Plane. ANTARES data from 2007 to 2013 have been analysed and upper limits on the neutrino production from the central region of our galaxy have been set.

Measurement of the 0.511 MeV #betta# ray line from the galactic center

International Nuclear Information System (INIS)

Jardim, J.O.D.; Benson, J.L.; Jardim, M.V.A.; Martin, I.M.

1981-02-01

The detection of the 0.511 MeV electron-positron annihilation line coming from the Galactic Center can provide the means to estimate the rate of positron production and to test some theoretical sources of positrons. The result of the measurements of the 0.511 MeV line flux made in a gamma-ray experiment on board a stratospheric balloon is presented. Thedetector field of view looked at the galactic longitude range-31 0 0 . The observed flux is (6.70 + - 0.85)x10 - 3 photons cm - 2 s - 1 , which is in good agreement with the expected flux when assuming that the Galactic Center is a line source emitting uniformly. (Author) [pt

The MACHO Project Sample of Galactic Bulge High-Amplitude Scuti Stars: Pulsation Behavior and Stellar Properties

International Nuclear Information System (INIS)

Bennett, D.P.; Cook, K.H.; Freeman, K.C.; Geha, M.; Griest, K.; Lehner, M.J.; Marshall, S.L.; McNamara, B.J.; Minniti, D.; Nelson, C.; Peterson, B.A.; Popowski, P.; Pratt, M.R.; Quinn, P.J.; Rodgers, A.W.; Sutherland, W.; Templeton, M.R.; Vandehei, T.; Welch, D.L.

1999-01-01

We have detected 90 objects with periods and lightcurve structure similar to those of field(delta) Scuti stars, using the Massive Compact Halo Object (MACHO) Project database of Galactic bulge photometry. If we assume similar extinction values for all candidates and absolute magnitudes similar to those of other field high-amplitude(delta) Scuti stars (HADS), the majority of these objects lie in or near the Galactic bulge. At least two of these objects are likely foreground(delta) Scuti stars, one of which may be an evolved nonradial pulsator, similar to other evolved, disk-population(delta) Scuti stars. We have analyzed the light curves of these objects and find that they are similar to the light curves of field(delta) Scuti stars and the(delta) Scuti stars found by the Optical Gravitational Lens Experiment (OGLE). However, the amplitude distribution of these sources lies between those of low- and high-amplitude(delta) Scuti stars, which suggests that they may be an intermediate population. We have found nine double-mode HADS with frequency ratios ranging from 0.75 to 0.79, four probable double- and multiple-mode objects, and another four objects with marginal detections of secondary modes. The low frequencies (5-14 cycles d(sup -1)) and the observed period ratios of(approx)0.77 suggest that the majority of these objects are evolved stars pulsating in fundamental or first overtone radial modes

Five-colour photometry of early-type stars in the direction of galactic X-ray sources

International Nuclear Information System (INIS)

Van Paradijs, J.; Van Amerongen, S.; Damen, E.; Van der Woerd, H.

1986-01-01

We present the results of five-colour photometry of 551 O- and B-type stars located in 17 fields of a few square degrees around galactic X-ray sources. From a comparison of reddening-free combinations of colour indices with theoretical values, calculated for model atmospheres of Kurucz, we derive effective temperature and surface gravity for these stars. In addition we find their absolute magnitude by combining these parameters with the results of evolutionary calculations of massive stars. These effective temperatures are in good agreement with the temperature scale of Bohm-Vitense for stars of luminosity classes II to V. For the supergiants the effective temperatures are about 40% higher. For stars of luminosity classes III to V the absolute magnitudes we find agree well with the results of independent luminosity calibrations of spectral types, but for brighter stars they deviate systematically. We suspect that the origin of these deviations lies in the failure of present low-gravity model atmospheres to represent supergiant atmospheres. We have used the photometric data to study the interstellar reddening in the direction of the X-ray sources

GALACTIC AND EXTRAGALACTIC SUPERNOVA REMNANTS AS SITES OF PARTICLE ACCELERATION

Directory of Open Access Journals (Sweden)

Manami Sasaki

2013-12-01

Full Text Available Supernova remnants, owing to their strong shock waves, are likely sources of Galactic cosmic rays. Studies of supernova remnants in X-rays and gamma rays provide us with new insights into the acceleration of particles to high energies. This paper reviews the basic physics of supernova remnant shocks and associated particle acceleration and radiation processes. In addition, the study of supernova remnant populations in nearby galaxies and the implications for Galactic cosmic ray distribution are discussed.

Custom chipset and compact module design for a 75–110 GHz laboratory signal source

International Nuclear Information System (INIS)

Morgan, Matthew A; Boyd, Tod A; Castro, Jason J

2016-01-01

We report on the development and characterization of a compact, full-waveguide bandwidth (WR-10) signal source for general-purpose testing of mm-wave components. The monolithic microwave integrated circuit (MMIC) based multichip module is designed for compactness and ease-of-use, especially in size-constrained test sets such as a wafer probe station. It takes as input a cm-wave continuous-wave (CW) reference and provides a factor of three frequency multiplication as well as amplification, output power adjustment, and in situ output power monitoring. It utilizes a number of custom MMIC chips such as a Schottky-diode limiter and a broadband mm-wave detector, both designed explicitly for this module, as well as custom millimeter-wave multipliers and amplifiers reported in previous papers. (paper)

Millimeter Wavelength Observations of Galactic Sources with the Mobile Anisotropy Telescope (MAT)

Science.gov (United States)

Cruz, K. L.; Caldwell, R.; Devlin, M. J.; Dorwart, W. B.; Herbig, T.; Miller, A. D.; Nolta, M. R.; Page, L. A.; Puchalla, J. L.; Torbet, E.; Tran, H. T.

1999-12-01

The Mobile Anisotropy Telescope (MAT) has completed two observing seasons (1997 and 1998) in Chile from the Cerro Toco site. Although the primary goal of MAT was to measure anisotropy in the Cosmic Microwave Background (CMB) radiation, the chosen observation scheme also allowed daily viewing of the Galactic Plane. We present filtered maps at 30, 40 and 144 GHz of a region of the Galactic Plane which contains several millimeter-bright regions including the Carinae nebula and IRAS 11097-6102. We report the best fit brightness temperatures as well as the total flux densities in the MAT beams (0.9, 0.6 and 0.2 degrees FWHM) . The data are calibrated with respect to Jupiter whose flux is known to better than 8% in all frequency bands. This work was funded by the National Science Foundation and the Packard Foundation.

Radio and x-ray observations of compact sources in or near supernova remnants

International Nuclear Information System (INIS)

Seaquist, E.R.; Gilmore, W.S.

1982-01-01

We present VLA multifrequency radio observations of six compact radio sources from the list of nine objects proposed by Ryle et al. [Nature 276, 571 (1978)] as a new class of radio star, possibly the stellar remnants of supernovae. We also present the results of a search for x-ray emission from four of these objects with the Einstein observatory. The radio observations provide information on spectra, polarization, time variability, angular structure, and positions for these sources. The bearing of these new data on the nature of the sources is discussed. One particularly interesting result is that the polarization and angular-size measurements are combined in an astrophysical argument to conclude that one of the sources (2013+370) is extragalactic. No x-ray emission was detected from any of the four objects observed, but an extended x-ray source was found coincident with the supernova remnant G 33.6+0.1 near 1849+005. Our measurements provide no compelling arguments to consider any of the six objects studied as radio stars

The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole

Energy Technology Data Exchange (ETDEWEB)

Witzel, G.; Sitarski, B. N.; Ghez, A. M.; Morris, M. R.; Hees, A.; Do, T.; Naoz, S.; Boehle, A.; Martinez, G.; Chappell, S.; Meyer, L.; Yelda, S.; Becklin, E. E. [Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095-1547 (United States); Lu, J. R. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Schödel, R. [Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia S/N, E-18008 Granada (Spain); Matthews, K., E-mail: witzel@astro.ucla.edu [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

2017-09-20

We present new adaptive optics (AO) imaging and spectroscopic measurements of Galactic center source G1 from W. M. Keck Observatory. Our goal is to understand its nature and relationship to G2, which is the first example of a spatially resolved object interacting with a supermassive black hole (SMBH). Both objects have been monitored with AO for the past decade (2003–2014) and are comparatively close to the black hole ( a {sub min} ∼ 200–300 au) on very eccentric orbits ( e {sub G1} ∼ 0.99; e {sub G2} ∼ 0.96). While G2 has been tracked before and during periapsis passage ( T {sub 0} ∼ 2014.2), G1 has been followed since soon after emerging from periapsis ( T {sub 0} ∼ 2001.3). Our observations of G1 double the previously reported observational time baseline, which improves its orbital parameter determinations. G1's orbital trajectory appears to be in the same plane as that of G2 but with a significantly different argument of periapsis (Δ ω = 21° ± 4°). This suggests that G1 is an independent object and not part of a gas stream containing G2, as has been proposed. Furthermore, we show for the first time that (1) G1 is extended in the epochs closest to periapsis along the direction of orbital motion, and (2) it becomes significantly smaller over time (450 au in 2004 to less than 170 au in 2009). Based on these observations, G1 appears to be the second example of an object tidally interacting with an SMBH. G1's existence 14 yr after periapsis, along with its compactness in epochs further from the time of periapsis, suggest that this source is stellar in nature.

Review of decametric radio astronomy - instruments and science

International Nuclear Information System (INIS)

Erickson, W.C.; Cane, H.V.

1987-01-01

The techniques and instruments used in Galactic and extragalactic radio astronomy at dkm wavelengths are surveyed, and typical results are summarized. Consideration is given to the large specialized phased arrays used for early surveys, the use of wideband elements to increase frequency agility, experimental VLBI observations, and limitations on ground-based observations below about 10 MHz (where the proposed LF Space Array, with resolution 0.5-5 arcmin, could make a major contribution). Observations discussed cover the Galactic center, the Galactic background radiation, SNRs, compact Galactic sources, the ISM, and large extragalactic sources. 38 references

High resolution far-infrared survey of A section of the galactic plane. I. The nature of the sources

International Nuclear Information System (INIS)

Jaffe, D.T.; Stier, M.T.; Fazio, G.G.

1982-01-01

We have surveyed a 7.5 deg 2 portion of the galactic plane between l/sup II/ = 10 0 and l/sup II/ = 16 0 at 70 μm with a 1' beam. We present far-infrared, radio continuum, and 12 CO and 13 CO line observations of the 42 far-infrared sources in the survey region. The sources range in luminosity from 4 x 10 3 to 3 x 10 6 L/sub sun/. Most are associated with 12 CO peaks. More than half of the sources have associated H 2 O maser emission. Half have associated radio continuum emission at a limit of 100 mJy. Eight sources have radio emission at weaker levels. In a number of cases, the far-infrared source is smaller than its associated radio source. This difference can be explained in the context of the ''blister'' picture of H II regions. One group of sources emits many fewer Lyman continuum photons than expected, given the far-infrared luminosities. We examine a number of possible reasons for this and conclude that the most reasonable explanation is that clusters of early type stars rather than single stars excite the far-infrared sources. We examine the energetics in the molecular clouds surrounding the infrared sources and conclude that the sources could supply the energy to explain the observed temperature structure and velocity field in the molecular gas

Development of a compact ECR ion source for various ion production

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, M., E-mail: m-mura@nirs.go.jp; Hojo, S.; Iwata, Y.; Katagiri, K.; Sakamoto, Y.; Kitagawa, A. [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Takahashi, N. [Sumitomo Heavy Industries, Ltd., 19 Natsushima, Yokosuka, Kanagawa 237-8555 (Japan); Sasaki, N.; Fukushima, K.; Takahashi, K.; Suzuki, T.; Sasano, T. [Accelerator Engineering Corporation, 3-8-5 Konakadai, Inage, Chiba 263-0043 (Japan); Uchida, T.; Yoshida, Y. [Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama 350-8585 (Japan); Hagino, S.; Nishiokada, T.; Kato, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan)

2016-02-15

There is a desire that a carbon-ion radiotherapy facility will produce various ion species for fundamental research. Although the present Kei2-type ion sources are dedicated for the carbon-ion production, a future ion source is expected that could provide: (1) carbon-ion production for medical use, (2) various ions with a charge-to-mass ratio of 1/3 for the existing Linac injector, and (3) low cost for modification. A prototype compact electron cyclotron resonance (ECR) ion source, named Kei3, based on the Kei series has been developed to correspond to the Kei2 type and to produce these various ions at the National Institute of Radiological Sciences (NIRS). The Kei3 has an outer diameter of 280 mm and a length of 1120 mm. The magnetic field is formed by the same permanent magnet as Kei2. The movable extraction electrode has been installed in order to optimize the beam extraction with various current densities. The gas-injection side of the vacuum chamber has enough space for an oven system. We measured dependence of microwave frequency, extraction voltage, and puller position. Charge state distributions of helium, carbon, nitrogen, oxygen, and neon were also measured.

Galactic sprinklers

International Nuclear Information System (INIS)

Vandeusen, W.

1984-01-01

It is believed by many astronomers that gravitation is responsible for holding a strong whirlpool of hot, dense material together at the center of the Milky Way galaxy. However, the galactic-sprinkler model suggests that the whirlpool is not being held together, and that the stars, gas and dust within the spirals are being thrown outward. It is also suggested that much of the ejected material eventually returns to the galactic center, as do stars within our stellar neighborhood. The material is believed to be subjected to extreme changes in the gravitational time rate which may cause it to follow an inbound spiral that is basically similar to the outbound spiral. Radio studies also indicate that the galactic arms on either side of the galactic center move at different velocities and in different directions with respect to our location and that the whole group of stars in the vicinity of the solar system may be moving outward from the galactic center at a velocity of about 40 kps. Through the use of velocity data in kps, and distance data in light years, the radial component of the sun's trajectory can be estimated with respect to time by a parabola. The spiral trajectory of the sun can be calculated and plotted on polar coordinates by combining both the radial component and tangential component (230 kps)

A study of electron-positron pair equilibria in models of compact X- and gamma-ray sources

International Nuclear Information System (INIS)

Bjoernsson, G.

1990-01-01

Thermal electron-positron pair equilibria in two temperature models of compact x ray and gamma ray sources are studied. The pairs are assumed to be heated by Coulomb interaction with the much hotter protons and cooled by bremsstrahlung emission, Compton scattering, and annihilation. Two parameters, the proton optical depth and the compactness, characterize each equilibrium state. It is shown that a careful account of the energy balance is very important when the stability properties of the pair equilibria in a spherical plasma cloud are determined. The equilibria are found to be unstable in a very limited range of compactness and proton optical depth. This particular instability is unlikely to be the cause of the observed variability of the compact sources and implies that it is possible to build up high pair densities by a thermal mechanism in two temperature environments. The most important result considers the effects of pairs on the structure of geometrically and effectively optically thin accretion disks. A new approach for solving for the equilibrium structure of the disks is presented. In effect, the pair equilibrium states are projected into the space spanned by the disk structure parameters. This allows a direct visualization of all possible disk solutions at once. Each solution profile needs to be calculated only once and a complete disk solution is obtained by a simple radial coordinate transformation. The disk solutions are thus seen to be scale free in terms of the radial coordinate as well as in terms of the mass of the central object and the accretion rate. Two particular disk solutions are given. It is shown that including electron-positron pairs in the disk structure calculations leads to a breakdown of the thin disk assumptions and that more detailed disk modeling is required before electron-positron pairs can be self-consistently included

Photoneutron source based on a compact 10 MeV betatron

International Nuclear Information System (INIS)

Bell, Z.W.; Chaklov, V.L.; Golovkov, V.M.

1998-01-01

Accelerator-based photoneutron sources have enjoyed wide use and offer the advantages of long term stability, ease of control and absence of radioactive materials. The authors report here measurements of the yield of photoneutrons from a neutron generator using a compact betatron (466 kg total weight, 900 by 560 by 350 mm betatron dimensions) at the Institute of Introscopy of the Tomsk Polytechnic University. Electrons were accelerated to energies up to 10 MeV and produced a bremsstrahlung beam with a dose rate of 0.16 Gy/min (at 10 MeV, 1 meter from the bremsstrahlung target) to irradiate LiD, Be, depleted U, and Pb neutron-producing targets. The angular distributions of photoneutrons produced by bremsstrahlung beams were measured with a long counter and integrated to determine neutron yield. In addition, neutron time of flight spectra were recorded from all targets using a 15 meter flight path perpendicular to the photon beam. The maximum observed yields were 5.2 x 10 4 n/rad/gram target obtained with LiD, 1.7 x 10 4 n/rad/gram from Be, 3.3 x 10 3 n/rad/gram from U, and 7.5 x 10 2 n/rad/gram from Pb. Optimization of target dimensions, shape, and positioning is expected to increase the yield from the LiD target by a factor of 35. With the increased yield, this compact betatron-based system could find application in the interrogation of waste containers for fissile material

Research and Development of Landmine Detection System by a Compact Fusion Neutron Source

International Nuclear Information System (INIS)

Yoshikawa, Kiyoshi; Masuda, Kai; Toku, Hisayuki; Nagasaki, Kazunobu; Mizutani, Toshiyuki; Takamatsu, Teruhisa; Imoto, Masaki; Yamamoto, Yasushi; Ohnishi, Masami; Osawa, Hodaka; Hotta, Eiki; Kohno, Toshiyuki; Okino, Akitoshi; Watanabe, Masato; Yamauchi, Kunihito; Yuura, Morimasa; Shiroya, Seiji; Misawa, Tsuyoshi; Mori, Takamasa

2005-01-01

Current results are described on the research and development of an advanced anti-personnel landmine detection system by using a compact discharge-type fusion neutron source called IECF (Inertial-Electrostatic Confinement Fusion). Landmines are to be identified through backscattering of neutrons, and specific-energy capture γ-rays by hydrogen and nitrogen atoms in the landmine explosives.For this purpose, improvements in the IECF were made by various methods to achieve a drastic enhancement of neutron yields of more than 10 8 n/s in pulsed operation. This required R and D on the power source, as well as analysis of envisaged detection systems with multi-sensors. The results suggest promising and practical features for humanitarian landmine detection, particularly, in Afghanistan

A compact rf driven H- ion source for linac injection

International Nuclear Information System (INIS)

Rymer, J.P.; Engeman, G.A.; Hamm, R.W.; Potter, J.M.

1991-01-01

A compact rf driven H - ion source has been developed for use as an injector for the AccSys radio frequency quadrupole (RFQ) linacs. A multicusp magnetic bucket geometry developed at Lawrence Berkeley Laboratory confines the plasma created by an antenna driven by 35 kW (peak) of pulsed rf power at 1.8 MHz. A three electrode system is used to extract and accelerate the H - beam, which is then focused into the RFQ by an einzel lens. Permanent magnets in the extraction region sweep electrons onto the second electrode at energies up to half of the full acceleration voltage. A fast pulsed valve allows the hydrogen gas supply to be pulsed, thus minimizing the average gas flow rate into the system. The design features and performance data from the prototype are discussed

A compact and continuously driven supersonic plasma and neutral source

Energy Technology Data Exchange (ETDEWEB)

Asai, T.; Itagaki, H.; Numasawa, H.; Terashima, Y.; Hirano, Y. [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan); Hirose, A. [Plasma Physics Laboratory, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada)

2010-10-15

A compact and repetitively driven plasma source has been developed by utilizing a magnetized coaxial plasma gun (MCPG) for diagnostics requiring deep penetration of a large amount of neutral flux. The system consists of a MCPG 95mm in length with a DN16 ConFlat connection port and an insulated gate bipolar transistor (IGBT) inverter power unit. The power supply consists of an array of eight IGBT units and is able to switch the discharge on and off at up to 10 kV and 600 A with a maximum repetitive frequency of 10 kHz. Multiple short duration discharge pulses maximize acceleration efficiency of the plasmoid. In the case of a 10 kHz operating frequency, helium-plasmoids in the velocity range of 20 km/s can be achieved.

A compact and continuously driven supersonic plasma and neutral source.

Science.gov (United States)

Asai, T; Itagaki, H; Numasawa, H; Terashima, Y; Hirano, Y; Hirose, A

2010-10-01

A compact and repetitively driven plasma source has been developed by utilizing a magnetized coaxial plasma gun (MCPG) for diagnostics requiring deep penetration of a large amount of neutral flux. The system consists of a MCPG 95mm in length with a DN16 ConFlat connection port and an insulated gate bipolar transistor (IGBT) inverter power unit. The power supply consists of an array of eight IGBT units and is able to switch the discharge on and off at up to 10 kV and 600 A with a maximum repetitive frequency of 10 kHz. Multiple short duration discharge pulses maximize acceleration efficiency of the plasmoid. In the case of a 10 kHz operating frequency, helium-plasmoids in the velocity range of 20 km/s can be achieved.

Experimental demonstration of a compact epithermal neutron source based on a high power laser

Science.gov (United States)

Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Raspino, D.; Ansell, S.; Wilson, L. A.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Kelleher, J.; Murphy, C. D.; Notley, M.; Rusby, D. R.; Schooneveld, E.; Borghesi, M.; McKenna, P.; Rhodes, N. J.; Neely, D.; Brenner, C. M.; Kar, S.

2017-07-01

Epithermal neutrons from pulsed-spallation sources have revolutionised neutron science allowing scientists to acquire new insight into the structure and properties of matter. Here, we demonstrate that laser driven fast (˜MeV) neutrons can be efficiently moderated to epithermal energies with intrinsically short burst durations. In a proof-of-principle experiment using a 100 TW laser, a significant epithermal neutron flux of the order of 105 n/sr/pulse in the energy range of 0.5-300 eV was measured, produced by a compact moderator deployed downstream of the laser-driven fast neutron source. The moderator used in the campaign was specifically designed, by the help of MCNPX simulations, for an efficient and directional moderation of the fast neutron spectrum produced by a laser driven source.

Development of X-ray photoelectron microscope with a compact X-ray source generated by line-focused laser irradiation

International Nuclear Information System (INIS)

Yamaguchi, N.; Takahashi, Z.; Nishimura, Y.; Watanabe, K.; Okamoto, Y.; Sakata, A.; Azuma, H.; Hara, T.

2005-01-01

A laboratory-sized X-ray photoelectron microscope was constructed using a compact X-ray source produced by line-focused laser irradiation. The system is a scanning type photoelectron microscope where X-ray beam is micro-focused via Schwarzschild optics. A compact laser-plasma X-ray source has been developed with a YAG laser, a line-focus lens assembly, an Al tape-target driver and a debris prevention system. The 13.1 nm X-ray was delivered along line plasma whose length was 0.6 or 11 mm with higher intensity than that from a point-focused source. The Schwarzschild optics having the designed demagnification of 224, which was coated with Mo/Si multilayers for 13.1 nm X-ray, was set on the beamline 1 m distant from the source. The electron energy analyser was a spherical capacitor analyser with the photoelectron image detection system that was suited for detection of vast photoelectrons excited by an X-ray pulse of ns-order duration. The spatial resolution less than 5 μm has been confirmed from the variation of As 3d electron intensity along the position of the GaAs sample coated with a photo-resist test pattern

Simulation of the annihilation emission of galactic positrons

International Nuclear Information System (INIS)

Gillard, W.

2008-01-01

Positrons annihilate in the central region of our Galaxy. This has been known since the detection of a strong emission line centered on an energy of 511 keV in the direction of the Galactic center. This gamma-ray line is emitted during the annihilation of positrons with electrons from the interstellar medium. The spectrometer SPI, onboard the INTEGRAL observatory, performed spatial and spectral analyses of the positron annihilation emission. This thesis presents a study of the Galactic positron annihilation emission based on models of the different interactions undergone by positrons in the interstellar medium. The models are relied on our present knowledge of the properties of the interstellar medium in the Galactic bulge, where most of the positrons annihilate, and of the physics of positrons (production, propagation and annihilation processes). In order to obtain constraints on the positrons sources and physical characteristics of the annihilation medium, we compared the results of the models to measurements provided by the SPI spectrometer. (author)

H II REGION DRIVEN GALACTIC BUBBLES AND THEIR RELATIONSHIP TO THE GALACTIC MAGNETIC FIELD

Energy Technology Data Exchange (ETDEWEB)

Pavel, Michael D.; Clemens, D. P., E-mail: pavelmi@bu.edu, E-mail: clemens@bu.edu [Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215 (United States)

2012-12-01

The relative alignments of mid-infrared traced Galactic bubbles are compared to the orientation of the mean Galactic magnetic field in the disk. The orientations of bubbles in the northern Galactic plane were measured and are consistent with random orientations-no preferential alignment with respect to the Galactic disk was found. A subsample of H II region driven Galactic bubbles was identified, and as a single population they show random orientations. When this subsample was further divided into subthermal and suprathermal H II regions, based on hydrogen radio recombination linewidths, the subthermal H II regions showed a marginal deviation from random orientations, but the suprathermal H II regions showed significant alignment with the Galactic plane. The mean orientation of the Galactic disk magnetic field was characterized using new near-infrared starlight polarimetry and the suprathermal H II regions were found to preferentially align with the disk magnetic field. If suprathermal linewidths are associated with younger H II regions, then the evolution of young H II regions is significantly affected by the Galactic magnetic field. As H II regions age, they cease to be strongly linked to the Galactic magnetic field, as surrounding density variations come to dominate their morphological evolution. From the new observations, the ratios of magnetic-to-ram pressures in the expanding ionization fronts were estimated for younger H II regions.

Galactic bulge preferred over dark matter for the Galactic centre gamma-ray excess

Science.gov (United States)

Macias, Oscar; Gordon, Chris; Crocker, Roland M.; Coleman, Brendan; Paterson, Dylan; Horiuchi, Shunsaku; Pohl, Martin

2018-05-01

An anomalous gamma-ray excess emission has been found in the Fermi Large Area Telescope data1 covering the centre of the Galaxy2,3. Several theories have been proposed for this `Galactic centre excess'. They include self-annihilation of dark-matter particles4, an unresolved population of millisecond pulsars5, an unresolved population of young pulsars6, or a series of burst events7. Here, we report on an analysis that exploits hydrodynamical modelling to register the position of interstellar gas associated with diffuse Galactic gamma-ray emission. We find evidence that the Galactic centre excess gamma rays are statistically better described by the stellar over-density in the Galactic bulge and the nuclear stellar bulge, rather than a spherical excess. Given its non-spherical nature, we argue that the Galactic centre excess is not a dark-matter phenomenon but rather associated with the stellar population of the Galactic bulge and the nuclear bulge.

Compact Antenna Range

Data.gov (United States)

Federal Laboratory Consortium — Facility consists of a folded compact antenna range including a computer controlled three axis position table, parabolic reflector and RF sources for the measurement...

Bubbles, jets, and clouds in active galactic nuclei

International Nuclear Information System (INIS)

Smith, M.D.; Smarr, L.; Norman, M.L.; Wilson, J.R.

1983-01-01

The Blandford and Reese 1974 fluid twin-exhaust model for jet formation is thoroughly investigated. We perform detailed analytic calculations of all aspects of the cavity-nozzle structures for the nonrelativistic case: the preshock flow, the central shock, cavity flow, and the nozzle. Our analytic results are in excellent agreement with recent sophisticated numerical calculations. We find that for a given central confining gas cloud, only a finite range of jet powers is possible. The sound speed ratio between cavity and cloud must be less than 30. Central masses of approx.10 9 M/sub sun/ within 1 pc are necessary for high-powered (10 46 ergs s -1 ) extragalactic jets. For a fixed confining cloud sound speed C 0 , there are three regimes determined by the central engine's luminosity. For low luminosity, a stream of bubbles emerges; for a middle range of luminosities, a jet forms; for too high a luminosity, large clouds are emitted. In the jet regime we find that L/sub j/approx.C 0 5 . The critical dependence of jet power on confining cloud sound speed enables a schematic picture for active galactic nuclei to be proposed. Seyfert galaxies and quasars are placed in the bubble regime. Variable compact radio sources reach the cloud regime. Evolutionary paths are suggested and may provide an indirect test for this picture

Application of a compact diode pumped solid-state laser source for quantitative laser-induced breakdown spectroscopy analysis of steel

Science.gov (United States)

Tortschanoff, Andreas; Baumgart, Marcus; Kroupa, Gerhard

2017-12-01

Laser-induced breakdown spectroscopy (LIBS) technology holds the potential for onsite real-time measurements of steel products. However, for a mobile and robust LIBS measurement system, an adequate small and ruggedized laser source is a key requirement. In this contribution, we present tests with our compact high-power laser source, which, initially, was developed for ignition applications. The CTR HiPoLas® laser is a robust diode pumped solid-state laser with a passive Q-switch with dimensions of less than 10 cm3. The laser generates 2.5-ns pulses with 30 mJ at a maximum continuous repetition rate of about 30 Hz. Feasibility of LIBS experiments with the laser source was experimentally verified with steel samples. The results show that the laser with its current optical output parameters is very well-suited for LIBS measurements. We believe that the miniaturized laser presented here will enable very compact and robust portable high-performance LIBS systems.

A compact self-flowing lithium system for use in an industrial neutron source

Science.gov (United States)

Kalathiparambil, Kishor Kumar; Szott, Matthew; Jurczyk, Brian; Ahn, Chisung; Ruzic, David

2016-10-01

A compact trench module to flow liquid lithium in closed loops for handling high heat and particle flux have been fabricated and tested at UIUC. The module was designed to demonstrate the proof of concept in utilizing liquid metals for two principal objectives: i) as self-healing low Z plasma facing components, which is expected to solve the issues facing the current high Z components and ii) using flowing lithium as an MeV-level neutron source. A continuously flowing lithium loop ensures a fresh lithium interface and also accommodate a higher concentration of D, enabling advanced D-Li reactions without using any radioactive tritium. Such a system is expected to have a base yield of 10e7 n/s. For both the applications, the key success factor of the module is attaining the necessary high flow velocity of the lithium especially over the impact area, which will be the disruptive plasma events in fusion reactors and the incident ion beam for the neutron beam source. This was achieved by the efficient shaping of the trenches to exploit the nozzle effect in liquid flow. The compactness of the module, which can also be scaled as desired, was fulfilled by the use of high Tc permanent magnets and air cooled channels attained the necessary temperature gradient for driving the lithium. The design considerations and parameters, experimental arrangements involving lithium filling and attaining flow, data and results obtained will be elaborated. DOE SBIR project DE-SC0013861.

HESS J1741-302: a hidden accelerator in the Galactic plane

Science.gov (United States)

H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Angüner, E. O.; Arakawa, M.; Armand, C.; Arrieta, M.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bonnefoy, S.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Caroff, S.; Carosi, A.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Colafrancesco, S.; Condon, B.; Conrad, J.; Davids, I. D.; Decock, J.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Donath, A.; Drury, L. O.'c.; Dyks, J.; Edwards, T.; Egberts, K.; Emery, G.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Funk, S.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Garrigoux, T.; Gaté, F.; Giavitto, G.; Glawion, D.; Glicenstein, J. F.; Gottschall, D.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holch, T. L.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Malyshev, D.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; De Naurois, M.; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poireau, V.; Prokhorov, D. A.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Rauth, R.; Reimer, A.; Reimer, O.; Renaud, M.; De Los Reyes, R.; Rieger, F.; Rinchiuso, L.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Saito, S.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Shiningayamwe, K.; Simoni, R.; Sol, H.; Spanier, F.; Spir-Jacob, M.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steppa, C.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsirou, M.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Zorn, J.; Żywucka, N.; NANTEN Collaboration; Enokiya, R.; Fukui, Y.; Hayakawa, T.; Okuda, T.; Torii, K.; Yamamoto, H.

2018-04-01

The H.E.S.S. Collaboration has discovered a new very high energy (VHE, E > 0.1 TeV) γ-ray source, HESS J1741-302, located in the Galactic plane. Despite several attempts to constrain its nature, no plausible counterpart has been found so far at X-ray and MeV/GeV γ-ray energies, and the source remains unidentified. An analysis of 145-h of observations of HESS J1741-302 at VHEs has revealed a steady and relatively weak TeV source ( 1% of the Crab Nebula flux), with a spectral index of Γ = 2.3 ± 0.2stat ± 0.2sys, extending to energies up to 10 TeV without any clear signature of a cut-off. In a hadronic scenario, such a spectrum implies an object with particle acceleration up to energies of several hundred TeV. Contrary to most H.E.S.S. unidentified sources, the angular size of HESS J1741-302 is compatible with the H.E.S.S. point spread function at VHEs, with an extension constrained to be below 0.068° at a 99% confidence level. The γ-ray emission detected by H.E.S.S. can be explained both within a hadronic scenario, due to collisions of protons with energies of hundreds of TeV with dense molecular clouds, and in a leptonic scenario, as a relic pulsar wind nebula, possibly powered by the middle-aged (20 kyr) pulsar PSR B1737-30. A binary scenario, related to the compact radio source 1LC 358.266+0.038 found to be spatially coincident with the best fit position of HESS J1741-302, is also envisaged.

A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator

International Nuclear Information System (INIS)

Waldmann, Ole; Ludewigt, Bernhard

2010-01-01

We present recent work on the development of a microwave ion source that will be used in a high-yield compact neutron generator for active interrogation applications. The sealed tube generator will be capable of producing high neutron yields, 5 · 10 11 n/s for D-T and ∼ 1 · 10 10 n/s for D-D reactions, while remaining transportable. We constructed a microwave ion source (2.45 GHz) with permanent magnets to provide the magnetic field strength of 87.5 mT necessary for satisfying the electron cyclotron resonance (ECR) condition. Microwave ion sources can produce high extracted beam currents at the low gas pressures required for sealed tube operation and at lower power levels than previously used RF-driven ion sources. A 100 mA deuterium/tritium beam will be extracted through a large slit (60 · 6 mm 2 ) to spread the beam power over a larger target area. This paper describes the design of the permanent-magnet microwave ion source and discusses the impact of the magnetic field design on the source performance. The required equivalent proton beam current density of 40 mA/cm 2 was extracted at a moderate microwave power of 400 W with an optimized magnetic field.

Performances of a Compact, High-Power WB Source with Circular Polarization

Science.gov (United States)

Delmote, P.; Pinguet, S.; Bieth, F.

This paper presents the design and the performances of an embedded high-power microwave (HPM) wideband source, developed and built at the French-German Research Institute of Saint-Louis. The system was intended for dual use, homeland security, and military applications. It is powered by a 400 kV compact Marx generator with specificities in coaxial design and low energy. The slow monopolar signal from the Marx is sharpened using a pulse-forming stage, made of a switching module pressurized with nitrogen, followed by a monopulse-to-monocycle converter. The duration and rise times of this signal could be adjusted by varying the pressure and space between electrodes. Repetitive operations were performed up to 100 Hz during 10 s without a gas flow. Two kinds of antennas can be connected to the source. The first one is a TEM horn, with an optional dielectric lens, that radiates a vertically polarized UWB short pulse. The second one is a nine-turn helix, working in Kraus monopolar axial mode and radiating a circularly polarized wideband signal along the main axis. A dedicated conical reflector increases its directivity and bandwidth. The whole source is designed to be embedded inside an aluminum trailer, powered by batteries and remote controlled through an optical fiber.

Photoneutron source based on a compact 10 MeV betatron

International Nuclear Information System (INIS)

Chakhlov, V.L.; Bell, Z.W.; Golovkov, V.M.; Shtein, M.M.

1999-01-01

Accelerator-based photoneutron sources have enjoyed wide use and offer the advantages of long term stability, ease of control and absence of radioactive materials. We report here measurements of the yield of photoneutrons from a neutron generator using a compact betatron. Electrons were accelerated to energies up to 10 MeV and produced a bremsstrahlung beam with a dose rate of 0.16 Gy/min (at 10 MeV, 1 m from the bremsstrahlung target) to irradiate LiD, Be, depleted U, and Pb neutron-producing targets. The angular distributions of photoneutrons produced by bremsstrahlung beams were measured with a 'long' counter and integrated to determine neutron yield. In addition, neutron time of flight spectra were recorded from all targets using a 15.5 m flight path perpendicular to the photon beam. The maximum observed yields were 4.6x10 7 n/s obtained with 1 kg of LiD, 5.7x10 7 n/s from a 3.3 kg Be block, 6.2x10 6 n/s from 1.5 kg of depleted U, and 7.0x10 6 n/s from 10.7 kg of Pb. Optimization of target dimensions, shape, and positioning is expected to increase the yield from the LiD target by a factor of 35, while optimization of the other targets is expected to yield at most a factor of 10. With the increased yield and a deuteride target, this compact betatron-based system could find application in the interrogation of waste containers for fissile material

Examining Sites of Recent Star Formation in the Galactic Center: A Closer Look at the Arched Filaments and H HII Regions

Science.gov (United States)

Hankins, Matthew; Herter, Terry; Lau, Ryan; Morris, Mark; Mills, Elisabeth

2018-01-01

In this dissertation presentation, we analyze mid-infrared imaging of the Arched Filaments and H HII regions in the Galactic center taken with the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST). Examining these regions are of great interest because they provide insights on star formation in the Galactic center and the interactions massive stars have with the ISM. The Arched Filaments are a collection of molecular cloud ridges which are ionized by the nearby Arches star cluster, and give the appearance of large (~25 pc) arch-like structures. The H HII regions are a collection of HII regions just to the west of the Arches cluster (~5-15 pc). The origin of the stars powering the H HII regions is uncertain, as they may have formed in a nearby molecular cloud or could be ejected members of the Arches cluster. FORCAST observations of these regions were used to study the morphology and heating structure of the HII regions, as well as constrain their luminosities.Color-temperature maps of the Arched Filaments created with the FORCAST data reveals fairly uniform dust temperatures (~70-100 K) across the length filaments. The temperature uniformity of the clouds can be explained if they are heated by the Arches cluster but are located at a larger distance from the cluster than they appear. The density of the Arched Filaments clouds was estimated from the FORCAST data and was found to be below the threshold for tidal shearing, indicating that that the clouds will be destroyed by the strong tidal field near the Galactic center. To the west of the Arched Filaments, there is an interesting collection of HII regions, referred to as the H HII regions. These regions are likely heated by massive O/B type stars, and the morphology of the dust emission associated with these objects indicate a mixture of potential in situ formation mechanisms and interlopers. Interestingly, FORCAST imaging of the H HII regions also reveal several compact sources, which may be young

A radio search for planetary nebulae near the galactic center

International Nuclear Information System (INIS)

Isaacman, R.B.

1980-01-01

Because of galactic center is a hostile environment, and because planetaries are weak radio emitters, it is not clear a priori that one expects to detect any planetary nebulae at all in the nuclear region of the Galaxy. Therefore the expected lifetime and flux density distribution of galactic center nebulae is considered. The principal observational results from the Westerbork data, and the results of some pilot observations with the Very Large Array, which were intended to distinguish planetaries from other radio sources on an individual basis are given. (Auth.)

Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

Science.gov (United States)

Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

1996-01-01

An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

Modeling of a Compact Terahertz Source based on the Two-Stream Instability

Energy Technology Data Exchange (ETDEWEB)

Svimonishvili, Tengiz [Univ. of New Mexico, Albuquerque, NM (United States)

2016-05-17

THz radiation straddles the microwave and infrared bands of the electromagnetic spectrum, thus combining the penetrating power of lower-frequency waves and imaging capabilities of higher-energy infrared radiation. THz radiation is employed in various elds such as cancer research, biology, agriculture, homeland security, and environmental monitoring. Conventional vacuum electronic sources of THz radiation (e.g., fast- and slow-wave devices) either require very small structures or are bulky and expensive to operate. Optical sources necessitate cryogenic cooling and are presently capable of producing milliwatt levels of power at THz frequencies. We propose a millimeter and sub-millimeter wave source based on a well-known phenomenon called the two-stream instability. The two-beam source relies on lowenergy and low-current electron beams for operation. Also, it is compact, simple in design, and does not contain expensive parts that require complex machining and precise alignment. In this dissertation, we perform 2-D particle-in-cell (PIC) simulations of the interaction region of the two-beam source. The interaction region consists of a beam pipe of radius ra and two electron beams of radius rb co-propagating and interacting inside the pipe. The simulations involve the interaction of unmodulated (no initial energy modulation) and modulated (energy-modulated, seeded at a given frequency) electron beams. In addition, both cold (monoenergetic) and warm (Gaussian) beams are treated.

Isotopic composition of neon in the galactic cosmic rays: a high resolution measurement

International Nuclear Information System (INIS)

Greiner, D.E.; Wiedenbeck, M.E.; Bieser, F.S.; Crawford, H.J.; Heckman, H.H.; Lindstrom, P.J.

1979-06-01

A measurement of the isotopic composition of galactic cosmic ray neon in the energy range 70 to 260 MeV/amu has been made using the U.C. Berkeley HKH instrument aboard ISEE-3. A combination of high resolution and good statistical accuracy makes possible a precise determination of the local interplanetary neon composition. We find 22 Ne/ 20 Ne = 0.64 +- 0.07 and 21 Ne/ 20 Ne < 0.30 in local interplanetary space. These ratios, when interpreted in using standard galactic propagation and solar modulation models, yield cosmic ray source abundances which are inconsistent with a solar-like source composition

Physics of compact radio sources. I. Particle acceleration and flux variations

International Nuclear Information System (INIS)

Pacholczyk, A.G.; Scott, J.S.

1976-01-01

The observed patterns of variability of compact radio sources may be explained by assuming that the radio components are plasmons containing relativistic particles, and by applying a model with the following features: (1) the plasmons are ejected at high speed into the interstellar medium in the nuclei of active galaxies: (2) ram pressure confinement of the plasmons leads to Rayleigh-Taylor and Kelvin-Helmholtz instabilities therein; (3) turbulence is thereby introduced into the plasmons; (4) the turbulence amplifies the plasmon magnetic field (for a short period) and this leads to betatron aceleration of the relativistic particles; (5) the turbulence vortices continue to accelerate the particles by the second-order Fermi acceleration mechanism. The emission patterns are the result of the combination of these accelerations and adiabatic losses

Cosmic far-infrared background at high galactic latitudes

International Nuclear Information System (INIS)

Stecker, F.W.; Puget, J.L.; Fazio, G.G.

1977-01-01

We predict far-infrared background fluxes from various cosmic sources. These fluxes lie near the high-frequency side of the blackbody radiation spectrum. These sources could account for a significant fraction of the background radiation at frequencies above 400 GHz which might be misinterpreted as a ''Comptonization'' distortion of the blackbody radiation. Particular attention is paid to the possible contributions from external galaxies, from rich clusters of galaxies, and from galactic dust emission

Cosmic far-infrared background at high galactic latitudes

International Nuclear Information System (INIS)

Stecker, F.W.; Puget, J.L.; Fazio, G.G.

1976-12-01

Far-infrared background fluxes from various cosmic sources are predicted. These fluxes lie near the high-frequency side of the blackbody radiation spectrum. These sources could account for a significant fraction of the background radiation at frequencies above 400 GHz, which might be misinterpreted as a comptonization distortion of the blackbody radiation. Particular attention is paid to the possible contributions from external galaxies, rich clusters of galaxies and from galactic dust emission

Analyzing γ rays of the Galactic Center with deep learning

Science.gov (United States)

Caron, Sascha; Gómez-Vargas, Germán A.; Hendriks, Luc; Ruiz de Austri, Roberto

2018-05-01

We present the application of convolutional neural networks to a particular problem in gamma ray astronomy. Explicitly, we use this method to investigate the origin of an excess emission of GeV γ rays in the direction of the Galactic Center, reported by several groups by analyzing Fermi-LAT data. Interpretations of this excess include γ rays created by the annihilation of dark matter particles and γ rays originating from a collection of unresolved point sources, such as millisecond pulsars. We train and test convolutional neural networks with simulated Fermi-LAT images based on point and diffuse emission models of the Galactic Center tuned to measured γ ray data. Our new method allows precise measurements of the contribution and properties of an unresolved population of γ ray point sources in the interstellar diffuse emission model. The current model predicts the fraction of unresolved point sources with an error of up to 10% and this is expected to decrease with future work.

Galactic models

International Nuclear Information System (INIS)

Buchler, J.R.; Gottesman, S.T.; Hunter, J.H. Jr.

1990-01-01

Various papers on galactic models are presented. Individual topics addressed include: observations relating to galactic mass distributions; the structure of the Galaxy; mass distribution in spiral galaxies; rotation curves of spiral galaxies in clusters; grand design, multiple arm, and flocculent spiral galaxies; observations of barred spirals; ringed galaxies; elliptical galaxies; the modal approach to models of galaxies; self-consistent models of spiral galaxies; dynamical models of spiral galaxies; N-body models. Also discussed are: two-component models of galaxies; simulations of cloudy, gaseous galactic disks; numerical experiments on the stability of hot stellar systems; instabilities of slowly rotating galaxies; spiral structure as a recurrent instability; model gas flows in selected barred spiral galaxies; bar shapes and orbital stochasticity; three-dimensional models; polar ring galaxies; dynamical models of polar rings

Compact microwave ion source

International Nuclear Information System (INIS)

Leung, K.N.; Walther, S.; Owren, H.W.

1985-05-01

A small microwave ion source has been fabricated from a quartz tube with one end enclosed by a two grid accelerator. The source is also enclosed by a cavity operated at a frequency of 2.45 GHz. Microwave power as high as 500 W can be coupled to the source plasma. The source has been operated with and without multicusp fields for different gases. In the case of hydrogen, ion current density of 200 mA/cm -2 with atomic ion species concentration as high as 80% has been extracted from the source

The Chandra Source Catalog: Source Variability

Science.gov (United States)

Nowak, Michael; Rots, A. H.; McCollough, M. L.; Primini, F. A.; Glotfelty, K. J.; Bonaventura, N. R.; Chen, J. C.; Davis, J. E.; Doe, S. M.; Evans, J. D.; Evans, I.; Fabbiano, G.; Galle, E. C.; Gibbs, D. G., II; Grier, J. D.; Hain, R.; Hall, D. M.; Harbo, P. N.; He, X.; Houck, J. C.; Karovska, M.; Lauer, J.; McDowell, J. C.; Miller, J. B.; Mitschang, A. W.; Morgan, D. L.; Nichols, J. S.; Plummer, D. A.; Refsdal, B. L.; Siemiginowska, A. L.; Sundheim, B. A.; Tibbetts, M. S.; van Stone, D. W.; Winkelman, S. L.; Zografou, P.

2009-09-01

The Chandra Source Catalog (CSC) contains fields of view that have been studied with individual, uninterrupted observations that span integration times ranging from 1 ksec to 160 ksec, and a large number of which have received (multiple) repeat observations days to years later. The CSC thus offers an unprecedented look at the variability of the X-ray sky over a broad range of time scales, and across a wide diversity of variable X-ray sources: stars in the local galactic neighborhood, galactic and extragalactic X-ray binaries, Active Galactic Nuclei, etc. Here we describe the methods used to identify and quantify source variability within a single observation, and the methods used to assess the variability of a source when detected in multiple, individual observations. Three tests are used to detect source variability within a single observation: the Kolmogorov-Smirnov test and its variant, the Kuiper test, and a Bayesian approach originally suggested by Gregory and Loredo. The latter test not only provides an indicator of variability, but is also used to create a best estimate of the variable lightcurve shape. We assess the performance of these tests via simulation of statistically stationary, variable processes with arbitrary input power spectral densities (here we concentrate on results of red noise simulations) at variety of mean count rates and fractional root mean square variabilities relevant to CSC sources. We also assess the false positive rate via simulations of constant sources whose sole source of fluctuation is Poisson noise. We compare these simulations to an assessment of the variability found in real CSC sources, and estimate the variability sensitivities of the CSC.

Sealed operation of a rf driven ion source for a compact neutron generator to be used for associated particle imaging.

Science.gov (United States)

Wu, Y; Hurley, J P; Ji, Q; Kwan, J W; Leung, K N

2010-02-01

We present the recent development of a prototype compact neutron generator to be used in conjunction with the method of associated particle imaging for the purpose of active neutron interrogation. In this paper, the performance and device specifications of these compact generators that employ rf driven ion sources will be discussed. Initial measurements of the generator performance include a beam spot size of 1 mm in diameter and a neutron yield of 2x10(5) n/s with air cooling.

IGR J17454-2919: a new X-ray transient found by INTEGRAL/JEM-X close to the Galactic Center

DEFF Research Database (Denmark)

Chenevez, Jérôme; Brandt, Søren; Budtz-Jørgensen, Carl

2014-01-01

The JEM-X twin X-ray monitors on board the INTEGRAL satellite have again detected a new X-ray transient during the latest observation of the Galactic Center region. The new source named IGR J17454-2919 is found less than 24 arcmin from the Galactic Center. The source appears in both JEM-X 3-10 ke...

Prospects for Galactic TeV Neutrino Astronomy

Energy Technology Data Exchange (ETDEWEB)

Kistler, Matthew D [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)

2007-03-15

In just the last few years, the catalog of known Galactic TeV gamma-ray sources has grown dramatically, due to the abilities of current air Cerenkov telescopes to measure both the spectrum and morphology of the TeV emission. While these properties can be very well measured, they are not necessarily sufficient to determine whether the gamma rays are produced by leptonic or hadronic processes. However, if the gamma-ray emission is hadronic, there must be an accompanying flux of neutrinos, which can be determined from the observed gamma-ray spectrum. The upcoming km3 neutrino telescopes will allow for a direct test of the gamma-ray production mechanism and the possibility of examining the highest possible energies, with important consequences for our understanding of Galactic cosmic-ray production.

Prospects for Galactic TeV Neutrino Astronomy

International Nuclear Information System (INIS)

Kistler, Matthew D

2007-01-01

In just the last few years, the catalog of known Galactic TeV gamma-ray sources has grown dramatically, due to the abilities of current air Cerenkov telescopes to measure both the spectrum and morphology of the TeV emission. While these properties can be very well measured, they are not necessarily sufficient to determine whether the gamma rays are produced by leptonic or hadronic processes. However, if the gamma-ray emission is hadronic, there must be an accompanying flux of neutrinos, which can be determined from the observed gamma-ray spectrum. The upcoming km3 neutrino telescopes will allow for a direct test of the gamma-ray production mechanism and the possibility of examining the highest possible energies, with important consequences for our understanding of Galactic cosmic-ray production

Compact source of narrow-band counterpropagating polarization-entangled photon pairs using a single dual-periodically-poled crystal

International Nuclear Information System (INIS)

Gong, Yan-Xiao; Xie, Zhen-Da; Xu, Ping; Zhu, Shi-Ning; Yu, Xiao-Qiang; Xue, Peng

2011-01-01

We propose a scheme for the generation of counterpropagating polarization-entangled photon pairs from a dual-periodically-poled crystal. Compared with the usual forward-wave-type source, this source, in the backward-wave way, has a much narrower bandwidth. With a 2-cm-long bulk crystal, the bandwidths of the example sources are estimated to be 3.6 GHz, and the spectral brightnesses are more than 100 pairs/(s GHz mW). Two concurrent quasi-phase-matched spontaneous parametric down-conversion processes in a single crystal enable our source to be compact and stable. This scheme does not rely on any state projection and applies to both degenerate and nondegenerate cases, facilitating applications of the entangled photons.

ALMA view of a massive spheroid progenitor: a compact rotating core of molecular gas in an AGN host at z = 2.226

Science.gov (United States)

Talia, M.; Pozzi, F.; Vallini, L.; Cimatti, A.; Cassata, P.; Fraternali, F.; Brusa, M.; Daddi, E.; Delvecchio, I.; Ibar, E.; Liuzzo, E.; Vignali, C.; Massardi, M.; Zamorani, G.; Gruppioni, C.; Renzini, A.; Mignoli, M.; Pozzetti, L.; Rodighiero, G.

2018-05-01

We present ALMA observations at 107.291 GHz (band 3) and 214.532 GHz (band 6) of GMASS 0953, a star-forming galaxy at z = 2.226 hosting an obscured active galactic nucleus (AGN) that has been proposed as a progenitor of compact quiescent galaxies (QGs). We measure for the first time the size of the dust and molecular gas emission of GMASS 0953 that we find to be extremely compact (˜1 kpc). This result, coupled with a very high interstellar medium (ISM) density (n ˜ 105.5 cm-3), a low gas mass fraction (˜0.2), and a short gas depletion time-scale (˜150 Myr), implies that GMASS 0953 is experiencing an episode of intense star formation in its central region that will rapidly exhaust its gas reservoirs, likely aided by AGN-induced feedback, confirming its fate as a compact QG. Kinematic analysis of the CO(6-5) line shows evidence of rapidly rotating gas (Vrot = 320^{+92}_{-53} km s-1), as observed also in a handful of similar sources at the same redshift. On-going quenching mechanisms could either destroy the rotation or leave it intact leading the galaxy to evolve into a rotating QG.

Newly discovered IRAS QSO close to the Galactic plane

International Nuclear Information System (INIS)

Strauss, M.A.; Kirhakos, S.D.; Yahil, A.

1988-01-01

CCD observations of the IRAS QSO candidate I09149-6206 performed at CTIO during December 1987 are reported, including 564-806-nm spectroscopy obtained with the 1.5-m telescope and direct UVBRI imaging obtained with the 0.91-m telescope. The data are presented in tables and graphs and characterized in detail. It is found that the source is surrounded by a faint fuzz with low surface brightness and strong forbidden O III lines. Parameters determined include redshift z = 0.0571, Galactic latitude -9.2 deg, V magnitude 13.55, Galactic reddening E(B-V) = about 0.23, and absolute V magnitude about -24.87. 33 references

The MACHO Project Sample of Galactic Bulge High-Amplitude {delta} Scuti Stars: Pulsation Behavior and Stellar Properties

Energy Technology Data Exchange (ETDEWEB)

Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Becker, A. C.; Bennett, D. P.; Cook, K. H.; Freeman, K. C.; Geha, M.; Griest, K. (and others)

2000-06-20

We have detected 90 objects with periods and light-curve structures similar to those of field {delta} Scuti stars using the Massive Compact Halo Object (MACHO) Project database of Galactic bulge photometry. If we assume similar extinction values for all candidates and absolute magnitudes similar to those of other field high-amplitude {delta} Scuti stars (HADS), the majority of these objects lie in or near the Galactic bulge. At least two of these objects are likely foreground {delta} Scuti stars, one of which may be an evolved nonradial pulsator, similar to other evolved, disk-population {delta} Scuti stars. We have analyzed the light curves of these objects and find that they are similar to the light curves of field {delta} Scuti stars and the {delta} Scuti stars found by the Optical Gravitational Lens Experiment (OGLE). However, the amplitude distribution of these sources lies between those of low- and high-amplitude {delta} Scuti stars, which suggests that they may be an intermediate population. We have found nine double-mode HADS with frequency ratios ranging from 0.75 to 0.79, four probable double- and multiple-mode objects, and another four objects with marginal detections of secondary modes. The low frequencies (5-14 cycles day-1) and the observed period ratios of {approx}0.77 suggest that the majority of these objects are evolved stars pulsating in fundamental or first overtone radial modes. (c) 2000 The American Astronomical Society.

Planets in other universes: habitability constraints on density fluctuations and galactic structure

Energy Technology Data Exchange (ETDEWEB)

Adams, Fred C.; Coppess, Katherine R. [Physics Department, University of Michigan, Ann Arbor, MI 48109 (United States); Bloch, Anthony M., E-mail: fca@umich.edu, E-mail: kcoppess@umich.edu, E-mail: abloch@umich.edu [Mathematics Department, University of Michigan, Ann Arbor, MI 48109 (United States)

2015-09-01

Motivated by the possibility that different versions of the laws of physics could be realized within other universes, this paper delineates the galactic structure parameters that allow for habitable planets and revisits constraints on the amplitude Q of the primordial density fluctuations. Previous work indicates that large values of Q lead to galaxies so dense that planetary orbits cannot survive long enough for life to develop. Small values of Q lead to delayed star formation, loosely bound galaxies, and compromised heavy element retention. This work generalizes previous treatments in the following directions: [A] We consider models for the internal structure of the galaxies, including a range of stellar densities, and find the fraction of the resulting galactic real estate that allows for stable, long-lived planetary orbits. [B] For high velocity encounters, we perform a large ensemble of numerical simulations to estimate cross sections for the disruption of planetary orbits due to interactions with passing stars. [C] We consider the background radiation fields produced by the galaxies: if a galaxy is too compact, the night sky seen from a potentially habitable planet can provide more power than the host star. [D] One consequence of intense galactic background radiation fields is that some portion of the galaxy, denoted as the Galactic Habitable Zone, will provide the right flux levels to support habitable planets for essentially any planetary orbit including freely floating bodies (but excluding close-in planets). As the value of Q increases, the fraction of stars in a galaxy that allow for (traditional) habitable planets decreases due to both orbital disruption and the intense background radiation. However, the outer parts of the galaxy always allow for habitable planets, so that the value of Q does not have a well-defined upper limit (due to scattering or radiation constraints). Moreover, some Galactic Habitable Zones are large enough to support more

Planets in other universes: habitability constraints on density fluctuations and galactic structure

International Nuclear Information System (INIS)

Adams, Fred C.; Coppess, Katherine R.; Bloch, Anthony M.

2015-01-01

Motivated by the possibility that different versions of the laws of physics could be realized within other universes, this paper delineates the galactic structure parameters that allow for habitable planets and revisits constraints on the amplitude Q of the primordial density fluctuations. Previous work indicates that large values of Q lead to galaxies so dense that planetary orbits cannot survive long enough for life to develop. Small values of Q lead to delayed star formation, loosely bound galaxies, and compromised heavy element retention. This work generalizes previous treatments in the following directions: [A] We consider models for the internal structure of the galaxies, including a range of stellar densities, and find the fraction of the resulting galactic real estate that allows for stable, long-lived planetary orbits. [B] For high velocity encounters, we perform a large ensemble of numerical simulations to estimate cross sections for the disruption of planetary orbits due to interactions with passing stars. [C] We consider the background radiation fields produced by the galaxies: if a galaxy is too compact, the night sky seen from a potentially habitable planet can provide more power than the host star. [D] One consequence of intense galactic background radiation fields is that some portion of the galaxy, denoted as the Galactic Habitable Zone, will provide the right flux levels to support habitable planets for essentially any planetary orbit including freely floating bodies (but excluding close-in planets). As the value of Q increases, the fraction of stars in a galaxy that allow for (traditional) habitable planets decreases due to both orbital disruption and the intense background radiation. However, the outer parts of the galaxy always allow for habitable planets, so that the value of Q does not have a well-defined upper limit (due to scattering or radiation constraints). Moreover, some Galactic Habitable Zones are large enough to support more

Development of compact synchrotron light source LUNA for x-ray lithography

International Nuclear Information System (INIS)

Takahashi, M.; Mandai, S.; Hoshi, Y.; Kohno, Y.

1992-01-01

A compact synchrotron light source LUNA has been developed by Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI), especially for x-ray lithography. It consists of a 45-MeV linac as an electron injector and an 800-MeV synchrotron. The peak wavelength of synchrotron radiation is around 10 A. The installation of LUNA was completed in April 1989 at the Tsuchiura Facility of IHI. The synchrotron radiation was first observed in December 1989. A stored beam current of 50 mA at 800 MeV and a lifetime over 1 h have been achieved. At present, experiments are still continuing to increase the stored current and the lifetime. X-ray lithography testing is scheduled to begin in a clean room in this facility. This paper describes the outline of LUNA and the present status

The galactic distribution of pulsars

International Nuclear Information System (INIS)

Lyne, A.G.

1981-01-01

The galactic distribution of pulsars follows the general form of many population I objects in galactocentric radius, but has a wide distribution above and below the galactic plane due to high space velocities imparted to the pulsars at birth. The evidence for this model is described and the various factors involved in estimating the total galactic population and the galactic birthrate of pulsars are discussed. The various estimates of the galactic population which cluster around 5 x 10 5 are seen to be critically dependent upon the cut-off at low luminosities and upon the value of the mean electron density within 500 pc of the Earth. Estimates of the lifetimes of pulsars are available from both the characteristic ages and proper motion measurements and both give values of about 5 million years. The implied birthrate of one in every 10 years is barely compatible with most estimates of the galactic supernova rate. (Auth.)

Critical experiments in support of the CNPS [Compact Nuclear Power Source] program

International Nuclear Information System (INIS)

Hansen, G.E.; Audas, J.H.; Martin, E.R.; Pederson, R.A.; Spriggs, G.D.; White, R.H.

1988-01-01

Zero-power static and kinetic measurements have been made on a mock-up of the Compact Nuclear Power Source (CNPS), a graphite moderated, graphite reflected, U(19.9% 235 U) fueled reactor design. Critical configurations were tracked from a first clean configuration (184 most central fuel channels filled and all control rod and heat pipe channels empty) to a fully loaded configuration (all 492 fuel channels filled, core-length stainless steel pipe in the twelve heat-pipe channels, and approximately half-core-length boron carbide in the outer 4 control rod channels. Reactor physics data such as material worths and neutron lifetime are presented only for the clean and fully loaded configurations

ENHANCED WARM H2 EMISSION IN THE COMPACT GROUP MID-INFRARED ''GREEN VALLEY''

International Nuclear Information System (INIS)

Cluver, M. E.; Ogle, P.; Guillard, P.; Appleton, P. N.; Jarrett, T. H.; Rasmussen, J.; Lisenfeld, U.; Verdes-Montenegro, L.; Antonucci, R.; Bitsakis, T.; Charmandaris, V.; Boulanger, F.; Egami, E.; Xu, C. K.; Yun, M. S.

2013-01-01

We present results from a Spitzer mid-infrared spectroscopy study of a sample of 74 galaxies located in 23 Hickson Compact Groups (HCGs), chosen to be at a dynamically active stage of H I depletion. We find evidence for enhanced warm H 2 emission (i.e., above that associated with UV excitation in star-forming regions) in 14 galaxies (∼20%), with 8 galaxies having extreme values of L(H 2 S(0)-S(3))/L(7.7 μm polycyclic aromatic hydrocarbon), in excess of 0.07. Such emission has been seen previously in the compact group HCG 92 (Stephan's Quintet), and was shown to be associated with the dissipation of mechanical energy associated with a large-scale shock caused when one group member collided, at high velocity, with tidal debris in the intragroup medium. Similarly, shock excitation or turbulent heating is likely responsible for the enhanced H 2 emission in the compact group galaxies, since other sources of heating (UV or X-ray excitation from star formation or active galactic nuclei) are insufficient to account for the observed emission. The group galaxies fall predominantly in a region of mid-infrared color-color space identified by previous studies as being connected to rapid transformations in HCG galaxy evolution. Furthermore, the majority of H 2 -enhanced galaxies lie in the optical ''green valley'' between the blue cloud and red sequence, and are primarily early-type disk systems. We suggest that H 2 -enhanced systems may represent a specific phase in the evolution of galaxies in dense environments and provide new insight into mechanisms which transform galaxies onto the optical red sequence.

Nonlinear momentum compaction and coherent synchrotron radiation at the metrology light source. Low-α commissioning and development

International Nuclear Information System (INIS)

Ries, Markus

2014-01-01

Short pulses of synchrotron radiation are becoming an increasingly demanded tool in various fields of science. The generation of short synchrotron radiation pulses can be accomplished by different accelerator-based approaches such as free electron lasers, energy recovery linacs or electron storage rings. Linear accelerator driven free electron lasers are capable of generating intense pulses in the femtosecond regime at moderate repetition rates. In comparison, electron storage rings generate pulses of lower intensity with the advantage of large repetition rates. However, electron storage rings rely on radiation emitted by the same bunch(es) every turn, which are present in an equilibrium state. Thus making the electron storage ring a yet unchallenged source of short synchrotron radiation pulses in terms of stability and reproducibility. In addition, storage rings are capable to serve a large number of users simultaneously. In general, it is possible to distinguish the user community of short pulses at electron storage rings. The first user group is interested in time-resolution applying incoherent synchrotron radiation up to the X-ray regime. The second user group makes use of coherent synchrotron radiation emitted by short bunches at wavelengths large compared to the bunch dimensions, which commonly applies up to the THz-regime. Both user groups are interested in the high average power and stability available at electron storage rings. However, there is a current limitation for stable short bunch operation of electron storage rings, which is due to an instability driven by the emission of coherent synchrotron radiation. The subject of this thesis is the operation of an electron storage ring at a low momentum compaction to generate short electron bunches as a source for coherent synchrotron radiation. For this purpose the Metrology Light Source is ideally suited, as it is the first light source designed with the ability to adjust the three leading orders of the

Propagation of Galactic Cosmic Rays and Dark Matter indirect Detection

International Nuclear Information System (INIS)

Delahaye, Timur

2010-07-01

This thesis is dedicated to the study of propagation of cosmic electrons and positrons in the Milky Way and to the indirect detection of dark matter. The existence of dark matter is a hypothesis considered as reasonable from the point of view of cosmology, astrophysics and even particle physics. Nevertheless its detection still eludes us and it is not possible to verify this hypothesis by other means than gravitational one. A possible way to detect dark matter is to look for its annihilation or decay products among Galactic cosmic rays. During the last three years, data concerning cosmic ray electrons and positrons have been accumulated and have reached a remarkable precision. Such a precision requires from us to refine the theoretical models and to quantify the errors. This thesis addresses the study of all the sources of uncertainties affecting predictions of cosmic electrons and positron fluxes, primary and secondary, classical or from exotic origin. The greatest care has been dedicated to the sources and the propagation in the Galactic halo. Moreover a study of gamma and radio emissions associated to these cosmic rays is presented, again with the will of sizing uncertainties. Finally a status of the research for detection of annihilation or decay of Galactic dark matter is presented. (author)

Simulated Galactic methanol maser distribution to constrain Milky Way parameters

Science.gov (United States)

Quiroga-Nuñez, L. H.; van Langevelde, H. J.; Reid, M. J.; Green, J. A.

2017-08-01

Context. Using trigonometric parallaxes and proper motions of masers associated with massive young stars, the Bar and Spiral Structure Legacy (BeSSeL) survey has reported the most accurate values of the Galactic parameters so far. The determination of these parameters with high accuracy has a widespread impact on Galactic and extragalactic measurements. Aims: This research is aimed at establishing the confidence with which such parameters can be determined. This is relevant for the data published in the context of the BeSSeL survey collaboration, but also for future observations, in particular from the southern hemisphere. In addition, some astrophysical properties of the masers can be constrained, notably the luminosity function. Methods: We have simulated the population of maser-bearing young stars associated with Galactic spiral structure, generating several samples and comparing them with the observed samples used in the BeSSeL survey. Consequently, we checked the determination of Galactic parameters for observational biases introduced by the sample selection. Results: Galactic parameters obtained by the BeSSeL survey do not seem to be biased by the sample selection used. In fact, the published error estimates appear to be conservative for most of the parameters. We show that future BeSSeL data and future observations with southern arrays will improve the Galactic parameters estimates and smoothly reduce their mutual correlation. Moreover, by modeling future parallax data with larger distance values and, thus, greater relative uncertainties for a larger numbers of sources, we found that parallax-distance biasing is an important issue. Hence, using fractional parallax uncertainty in the weighting of the motion data is imperative. Finally, the luminosity function for 6.7 GHz methanol masers was determined, allowing us to estimate the number of Galactic methanol masers.

Direct electron acceleration in plasma waveguides for compact high-repetition-rate x-ray sources

International Nuclear Information System (INIS)

Lin, M-W; Jovanovic, I

2014-01-01

Numerous applications in fundamental and applied research, security, and industry require robust, compact sources of x-rays, with a particular recent interest in monochromatic, spatially coherent, and ultrafast x-ray pulses in well-collimated beams. Such x-ray sources usually require production of high-quality electron beams from compact accelerators. Guiding a radially polarized laser pulse in a plasma waveguide has been proposed for realizing direct laser acceleration (DLA), where the electrons are accelerated by the axial electric field of a co-propagating laser pulse (Serafim et al 2000 IEEE Trans. Plasma Sci. 28 1190). A moderate laser peak power is required for DLA when compared to laser wakefield acceleration, thus offering the prospect for high repetition rate operation. By using a density-modulated plasma waveguide for DLA, the acceleration distance can be extended with pulse guiding, while the density-modulation with proper axial structure can realize the quasi-phase matching between the laser pulses and electrons for a net gain accumulation (York et al 2008 Phys. Rev. Lett. 100 195001; York et al 2008 J. Opt. Soc. Am. B 25 B137; Palastro et al 2008 Phys. Rev. E 77 036405). We describe the development and application of a test particle model and particle-in-cell model for DLA. Experimental setups designed for fabrication of optically tailored plasma waveguides via the ignitor-heater scheme, and for generation and characterization of radially polarized short pulses used to drive DLA, are presented. (paper)

Study of potential applications of compact ECRIS to analytical system

International Nuclear Information System (INIS)

Kidera, M.; Takahashi, K.; Seto, Y.; Kishi, S.; Enomoto, S.; Nagamatsu, T.; Tanaka, T.

2012-01-01

The objective of this study is to develop a desktop-sized system of element mass analysis (element analysis system) with a compact electron cyclotron resonance (ECR) ion source in the ionization section. This system is different from other element analysis systems in terms of the effective use of ionization by ECR plasma. A compact ECR ion source is required to fit in the desktop-sized element analysis system. This paper reporting the development of the compact ECR ion source, is followed by the associated poster. (authors)

Compact approach to fusion power reactors

International Nuclear Information System (INIS)

Hagenson, R.L.; Krakowski, R.A.; Bathke, C.G.; Miller, R.L.

1984-01-01

The potential of the Reversed-Field Pinch (RFP) for development into an efficient, compact, copper-coil fusion reactor has been quantified by comprehensive parametric tradeoff studies. These compact systems promise to be competitive in size, power density, and cost to alternative energy sources. Conceptual engineering designs that largely substantiate these promising results have since been completed. This 1000-MWe(net) design is described along with a detailed rationale and physics/technology assessment for the compact approach to fusion

Millisecond Pulsars and the Galactic Center Excess

Science.gov (United States)

Gonthier, Peter L.; Koh, Yew-Meng; Kust Harding, Alice; Ferrara, Elizabeth C.

2017-08-01

Various groups including the Fermi team have confirmed the spectrum of the gamma- ray excess in the Galactic Center (GCE). While some authors interpret the GCE as evidence for the annihilation of dark matter (DM), others have pointed out that the GCE spectrum is nearly identical to the average spectrum of Fermi millisecond pul- sars (MSP). Assuming the Galactic Center (GC) is populated by a yet unobserved source of MSPs that has similar properties to that of MSPs in the Galactic Disk (GD), we present results of a population synthesis of MSPs from the GC. We establish parameters of various models implemented in the simulation code by matching characteristics of 54 detected Fermi MSPs in the first point source catalog and 92 detected radio MSPs in a select group of thirteen radio surveys and targeting a birth rate of 45 MSPs per mega-year. As a check of our simulation, we find excellent agreement with the estimated numbers of MSPs in eight globular clusters. In order to reproduce the gamma-ray spectrum of the GCE, we need to populate the GC with 10,000 MSPs having a Navarro-Frenk-White distribution suggested by the halo density of DM. It may be possible for Fermi to detect some of these MSPs in the near future; the simulation also predicts that many GC MSPs have radio fluxes S1400above 10 �μJy observable by future pointed radio observations. We express our gratitude for the generous support of the National Science Foundation (RUI: AST-1009731), Fermi Guest Investigator Program and the NASA Astrophysics Theory and Fundamental Program (NNX09AQ71G).

Probing the Large Faraday Rotation Measure Environment of Compact Active Galactic Nuclei

Directory of Open Access Journals (Sweden)

Alice Pasetto

2018-03-01

Full Text Available Knowing how the ambient medium in the vicinity of active galactic nuclei (AGNs is shaped is crucial to understanding generally the evolution of such cosmic giants as well as AGN jet formation and launching. Thanks to the new broadband capability now available at the Jansky Very Large Array (JVLA, we can study changes in polarization properties, fractional polarization, and polarization angles, together with the total intensity spectra of a sample of 14 AGNs, within a frequency range from 1 to 12 GHz. Depolarization modeling has been performed by means of so-called “qu-fitting” to the polarized data, and a synchrotron self absorption model has been used for fitting to the total intensity data. We found complex behavior both in the polarization spectra and in the total intensity spectra, and several Faraday components with a large rotation measure (RM and several synchrotron components were needed to represent these spectra. Here, results for three targets are shown. This new method of analyzing broadband polarization data through qu-fitting successfully maps the complex surroundings of unresolved objects.

The KMOS3D Survey: Rotating Compact Star-forming Galaxies and the Decomposition of Integrated Line Widths

Science.gov (United States)

Wisnioski, E.; Mendel, J. T.; Förster Schreiber, N. M.; Genzel, R.; Wilman, D.; Wuyts, S.; Belli, S.; Beifiori, A.; Bender, R.; Brammer, G.; Chan, J.; Davies, R. I.; Davies, R. L.; Fabricius, M.; Fossati, M.; Galametz, A.; Lang, P.; Lutz, D.; Nelson, E. J.; Momcheva, I.; Rosario, D.; Saglia, R.; Tacconi, L. J.; Tadaki, K.; Übler, H.; van Dokkum, P. G.

2018-03-01

Using integral field spectroscopy, we investigate the kinematic properties of 35 massive centrally dense and compact star-forming galaxies (SFGs; {log}{\\overline{M}}* [{M}ȯ ]=11.1, {log}({{{Σ }}}1{kpc}[{M}ȯ {kpc}}-2])> 9.5, {log}({M}* /{r}e1.5[{M}ȯ {kpc}}-1.5])> 10.3) at z ∼ 0.7–3.7 within the KMOS3D survey. We spatially resolve 23 compact SFGs and find that the majority are dominated by rotational motions with velocities ranging from 95 to 500 km s‑1. The range of rotation velocities is reflected in a similar range of integrated Hα line widths, 75–400 km s‑1, consistent with the kinematic properties of mass-matched extended galaxies from the full KMOS3D sample. The fraction of compact SFGs that are classified as “rotation-dominated” or “disklike” also mirrors the fractions of the full KMOS3D sample. We show that integrated line-of-sight gas velocity dispersions from KMOS3D are best approximated by a linear combination of their rotation and turbulent velocities with a lesser but still significant contribution from galactic-scale winds. The Hα exponential disk sizes of compact SFGs are, on average, 2.5 ± 0.2 kpc, 1–2× the continuum sizes, in agreement with previous work. The compact SFGs have a 1.4× higher active galactic nucleus (AGN) incidence than the full KMOS3D sample at fixed stellar mass with an average AGN fraction of 76%. Given their high and centrally concentrated stellar masses, as well as stellar-to-dynamical mass ratios close to unity, the compact SFGs are likely to have low molecular gas fractions and to quench on a short timescale unless replenished with inflowing gas. The rotation in these compact systems suggests that their direct descendants are rotating passive galaxies. Based on observations obtained at the Very Large Telescope (VLT) of the European Southern Observatory (ESO), Paranal, Chile (ESO program IDs 092A-0091, 093.A-0079, 094.A-0217, 095.A-0047, 096.A-0025, 097.A-0028, and 098.A-0045).

X-ray polarimetry. [aboard Ariel 5 and OSO 8 for observation of galactic sources

Science.gov (United States)

Long, K. S.; Chanan, G. A.; Helfand, D. J.; Ku, W. H.-M.; Novick, R.

1979-01-01

The method by which the Bragg-crystal X-ray polarimeters aboard Ariel 5 and OSO 8 operate is briefly described, and some results obtained with these instruments for six Galactic X-ray sources are summarized. A precision measurement of the linear polarization in the Crab Nebula at energies of 2.6 and 5.2 keV is presented. Evidence is given for polarization in Sco X-1, Cyg X-2, Cen X-3, and the X-ray transient A0620-00. The determined or estimated polarizations are approximately 19.2% at 2.6 keV and 19.5% at 5.2 keV for the Crab Nebula, 1.1% at 2.6 keV and 2.4% at 5.2 keV for Sco X-1, 2.5% at 2.6 keV and 9.8% at 5.2 keV for Cyg X-1, an upper limit of 13.5% for A0620-00, an upper limit of 13.5% to the time-averaged polarization of Cen X-3, and an apparent value of about 5% for Cyg X-2.

Analysis of nearly simultaneous x-ray and optical observations of active galactic nuclei

International Nuclear Information System (INIS)

Webb, J.R.

1988-01-01

Rosemary Hill optical and EINSTEIN X-ray observations of a sample of 36 galactic nuclei (AGN) were reduced and analyzed. Seventy-two x-ray observations of these sources were reduced, nineteen of which yielded spectral information. Of these spectra observations, significant hydrogen column densities above the galactic value were required for nine of the active galactic nuclei. X-ray variability was detected in eight of the eleven sources which were observed more than once by EINSTEIN. Correlations between the x-ray and optical luminosities were investigated using the Jefferys method of least squares. This method allows for errors in both variables. The results indicate a strong correlation between the x-ray and optical luminosities for the entire sample. Division of the sample into groups with similar optical variability characteristics show that the less violently violent variable AGN are more highly correlated than the violently variable blazars. Infrared and radio observations were combined with the x-ray and optical observations of six AGN. These sources were modelled in terms of the synchrotron-self-Compton model. The turnover frequency falls between the infrared and radio data and reliable estimates of this parameter are difficult to estimate. Therefore the results were found as a function of the turnover frequency. Four sources required relativistic bulk motion or beaming. Multifrequency spectra made at different times for one individual source, 0235+164, required different amounts of beaming to satisfy the x-ray observations. Sizes of the emitting regions for the sources modelled ranged from 0.5 parsec to 1.0 parsec

PROPERTIES OF THE COMPACT H II REGION COMPLEX G-0.02-0.07

International Nuclear Information System (INIS)

Mills, E.; Morris, M. R.; Lang, C. C.; Dong, H.; Wang, Q. D.; Cotera, A.; Stolovy, S. R.

2011-01-01

We present new extinction maps and high-resolution Paschen-alpha images of G-0.02-0.07, a complex of compact H II regions located adjacent to the M-0.02-0.07 giant molecular cloud, 6 pc in projection from the center of the Galaxy. These H II regions, which lie in projection just outside the boundary of the Sgr A East supernova remnant, represent one of the most recent episodes of star formation in the central parsecs of the Galaxy. The 1.87 μm extinctions of regions A, B, and C are almost identical, approximately 3.7 mag. Region D, in contrast, has a peak extinction of A 1.87 = 5.9 mag. Adopting an extinction law specific to the Galactic center, we find that these extinctions correspond to visual extinctions of A V = 45 and A V = 71. The similar and uniform extinctions of regions A, B, and C are consistent with that expected for foreground extinction in the direction of the Galactic center, suggesting that they lie at the front side of the M-0.02-0.07 molecular cloud. Region D is more compact, has a higher extinction, and is thus suspected to be younger and embedded in a dense core in a compressed ridge on the western edge of this cloud.

Simple, compact, high brightness source for x-ray lithography and x-ray radiography

International Nuclear Information System (INIS)

Hawryluk, A.M.

1986-01-01

A simple, compact, high brightness x-ray source has recently been built. This source utilizes a commercially available, cylindrical geometry electron beam evaporator, which has been modified to enhance the thermal cooling to the anode. Cooling is accomplished by using standard, low-conductivity laboratory water, with an inlet pressure of less than 50 psi, and a flow rate of approx.0.3 gal/min. The anode is an inverted cone geometry for efficient cooling. The x-ray source has a measured sub-millimeter spot size (FWHM). The anode has been operated at 1 KW e-beam power (10 KV, 100 ma). Higher operating levels will be investigated. A variety of different x-ray lines can be obtained by the simple interchange of anodes of different materials. Typical anodes are made from easily machined metals, or materials which are vacuum deposited onto a copper anode. Typically, a few microns of material is sufficient to stop 10 KV electrons without significantly decreasing the thermal conductivity through the anode. The small size and high brightness of this source make it useful for step and repeat exposures over several square centimeter areas, especially in a research laboratory environment. For an aluminum anode, the estimated Al-K x-ray flux at 10 cms from the source is 70 μW/cm 2

KECK OBSERVATIONS OF THE GALACTIC CENTER SOURCE G2: GAS CLOUD OR STAR?

Energy Technology Data Exchange (ETDEWEB)

Phifer, K.; Meyer, L.; Ghez, A. M.; Witzel, G.; Yelda, S.; Boehle, A.; Morris, M. R.; Becklin, E. E. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Do, T. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, M5S 3H4 (Canada); Lu, J. R. [Institute for Astronomy, University of Hawaii, Hilo, HI 96720 (United States); Matthews, K., E-mail: ghez@astro.ucla.edu [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

2013-08-10

We present new observations and analysis of G2-the intriguing red emission-line object which is quickly approaching the Galaxy's central black hole. The observations were obtained with the laser guide star adaptive optics systems on the W. M. Keck I and II telescopes (2006-2012) and include spectroscopy (R {approx} 3600) centered on the hydrogen Br{gamma} line as well as K' (2.1 {mu}m) and L' (3.8 {mu}m) imaging. Analysis of these observations shows the Br{gamma} line emission has a positional offset from the L' continuum. This offset is likely due to background source confusion at L'. We therefore present the first orbital solution derived from Br{gamma} line astrometry, which, when coupled with radial velocity measurements, results in a later time of closest approach (2014.21 {+-} 0.14), closer periastron (130 AU, 1600 R{sub s}), and higher eccentricity (0.9814 {+-} 0.0060) compared to a solution using L' astrometry. It is shown that G2 has no K' counterpart down to K' {approx} 20 mag. G2's L' continuum and the Br{gamma} line emission appears unresolved in almost all epochs, which implies that the bulk of the emission resides in a compact region. The observations altogether suggest that while G2 has a gaseous component that is tidally interacting with the central black hole, there is likely a central star providing the self-gravity necessary to sustain the compact nature of this object.

Infrared study of seven possible compact H II regions

International Nuclear Information System (INIS)

Sibille, F.; Lunel, M.; Bergeat, J.

1976-01-01

We report observations of seven possible compact H II regions in the infrared with the hydrogen spectrum in order to derive extinction and emission measures. The emission measure is compared with available radio data. For two sources, agreement is found between radio and infrared data. Infrared excess is found in four sources, its origin is discussed. Two sources cannot be interpreted as compact H II regions. (orig.) [de

TeV Gamma Rays From Galactic Center Pulsars

Energy Technology Data Exchange (ETDEWEB)

Hooper, Dan [Fermilab; Cholis, Ilias [Johns Hopkins U.; Linden, Tim [Ohio State U., CCAPP

2017-05-25

Measurements of the nearby pulsars Geminga and B0656+14 by the HAWC and Milagro telescopes have revealed the presence of bright TeV-emitting halos surrounding these objects. If young and middle-aged pulsars near the Galactic Center transfer a similar fraction of their energy into TeV photons, then these sources could dominate the emission that is observed by HESS and other ground-based telescopes from the innermost ~10^2 parsecs of the Milky Way. In particular, both the spectral shape and the angular extent of this emission is consistent with TeV halos produced by a population of pulsars. The overall flux of this emission requires a birth rate of ~100-1000 neutron stars per Myr near the Galactic Center, in good agreement with recent estimates.

Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

Energy Technology Data Exchange (ETDEWEB)

Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

2010-12-15

Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

Monitoring and Mapping the Galactic Bulge

Science.gov (United States)

Markwardt, Craig

Both neutron star and black hole binary transients are providing some of the most exciting RXTE science, and fortunately many are concentrated in the galactic bulge region. We propose to continue our twice weekly PCA scans of the region, which cover about 500 sq deg. The observations will be sensitive to new sources at the ~1 mCrab level (a factor of 10-60 more sensitive than the ASM in the region). We have had success finding new sources and new types of variability, including three millisecond pulsars, and new increased solid angle will improve the chances of finding more in the final RXTE years. We will continue efforts to search for variability in new and known sources. Companion follow-up proposals would be triggered by the results.

Angular Spectra of Polarized Galactic Foregrounds

OpenAIRE

Cho, Jung; Lazarian, A.

2003-01-01

It is believed that magnetic field lines are twisted and bend by turbulent motions in the Galaxy. Therefore, both Galactic synchrotron emission and thermal emission from dust reflects statistics of Galactic turbulence. Our simple model of Galactic turbulence, motivated by results of our simulations, predicts that Galactic disk and halo exhibit different angular power spectra. We show that observed angular spectra of synchrotron emission are compatible with our model. We also show that our mod...

A transient, flat spectrum radio pulsar near the Galactic Centre

Science.gov (United States)

Dexter, J.; Degenaar, N.; Kerr, M.; Deller, A.; Deneva, J.; Lazarus, P.; Kramer, M.; Champion, D.; Karuppusamy, R.

2017-06-01

Recent studies have shown possible connections between highly magnetized neutron stars ('magnetars'), whose X-ray emission is too bright to be powered by rotational energy, and ordinary radio pulsars. In addition to the magnetar SGR J1745-2900, one of the radio pulsars in the Galactic Centre (GC) region, PSR J1746-2850, had timing properties implying a large magnetic field strength and young age, as well as a flat spectrum. All characteristics are similar to those of rare, transient, radio-loud magnetars. Using several deep non-detections from the literature and two new detections, we show that this pulsar is also transient in the radio. Both the flat spectrum and large amplitude variability are inconsistent with the light curves and spectral indices of three radio pulsars with high magnetic field strengths. We further use frequent, deep archival imaging observations of the GC in the past 15 yr to rule out a possible X-ray outburst with a luminosity exceeding the rotational spin-down rate. This source, either a transient magnetar without any detected X-ray counterpart or a young, strongly magnetized radio pulsar producing magnetar-like radio emission, further blurs the line between the two categories. We discuss the implications of this object for the radio emission mechanism in magnetars and for star and compact object formation in the GC.

The end of the galactic cosmic ray spectrum

Energy Technology Data Exchange (ETDEWEB)

Stanev, Todor [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

2007-03-15

We discuss the region of transition between galactic and extragalactic cosmic rays. The exact shapes and compositions of these two components contains information about important parameters of powerful astrophysical sources and the conditions in extragalactic space as well as for the cosmological evolution of the sources of high energy cosmic rays. Several types of experimental data, including the exact shape of the ultrahigh energy cosmic rays, their chemical composition and their anisotropy, and the fluxes of cosmogenic neutrinos have to be included in the solution of this problem.

A high resolution atlas of the galactic plane at 12 microns and 25 microns

Science.gov (United States)

Price, Stephan D.; Korte, Rose M.; Sample, Rebecca S.; Kennealy, John P.; Gonsalves, Robert A.

1994-01-01

High resolution images of the 12 micron and 25 micron IRAS survey data from each HCON crossing the Galactic Plane are being created for those regions that the original IRAS processing labeled as confused. This encompasses the area within 100 deg longitude of the Galactic Center and within 3 deg to 10 deg of the Plane. The procedures used to create the images preserve the spatial resolution inherent in the IRAS instrument. The images are separated into diffuse and point source components and candidate sources are extracted from the point source image after non-linear spatial sharpening. Fluxes are estimated by convolving the candidate sources with the point response function and cross-correlating with the original point source image. A source is considered real if it is seen on at least two HCON's with a rather generous flux match but a stringent position criterion. A number of fields spanning a range of source densities from low to high have been examined. Initial analysis indicates that the imaging and extraction works quite well up to a source density of about 100 sources per square degree or down to roughly 0.8 Janskys.

Design of a compact synchrotron light source for medical applications at NIRS

International Nuclear Information System (INIS)

Torikoshi, M.; Endo, M.; Kumada, M.; Noda, K.; Yamada, S.; Kawachi, K.

1998-01-01

A synchrotron light source dedicated to medical applications is required to be compact for installation in limited spaces at hospitals. The NIRS storage ring, with a circumference of 44.8 m, is designed to accelerate electrons up to 1.8 GeV and to store a beam of 400 mA. The ring is composed of superconducting bending magnets for downsizing. A beam of 300 MeV is injected into the ring from a microtron operated at an L-band RF frequency. There are two superconducting multipole wigglers with nine poles and a maximum field of 8 T, which can produce a photon flux of about 1.4 x 10 13 photons s -1 mrad -1 (0.1% bandwidth) -1 at 33 keV used for coronary angiography

Radio observations of a galactic high energy gamma-ray source

Energy Technology Data Exchange (ETDEWEB)

Giacani, E.; Rovero, A.C. [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina)

2001-10-01

PSR B1706-44 is one of the very few galactic pulsars that has been discovered at TeV energies. PSR B1706-44 has been also detected in the X-ray domain. It has been suggested that the high energy radiation could be due to inverse Compton radiation from a pulsar wind nebula (PWN). It was reported on VLA high-resolution observations of a region around the pulsar PSR B1706-44 at 1.4, 4.8 and 8.4 GHz. The pulsar appears embedded in a synchrotron nebula. It was proposed that this synchrotron nebula is the radio counterpart of the high energy emission powered by the spin-down energy of the pulsar.

THE COMPACT, TIME-VARIABLE RADIO SOURCE PROJECTED INSIDE W3(OH): EVIDENCE FOR A PHOTOEVAPORATED DISK?

International Nuclear Information System (INIS)

Dzib, Sergio A.; Rodríguez-Garza, Carolina B.; Rodríguez, Luis F.; Kurtz, Stan E.; Loinard, Laurent; Zapata, Luis A.; Lizano, Susana

2013-01-01

We present new Karl G. Jansky Very Large Array (VLA) observations of the compact (∼0.''05), time-variable radio source projected near the center of the ultracompact H II region W3(OH). The analysis of our new data as well as of VLA archival observations confirms the variability of the source on timescales of years and for a given epoch indicates a spectral index of α = 1.3 ± 0.3 (S ν ∝ν α ). This spectral index and the brightness temperature of the source (∼6500 K) suggest that we are most likely detecting partially optically thick free-free radiation. The radio source is probably associated with the ionizing star of W3(OH), but an interpretation in terms of an ionized stellar wind fails because the detected flux densities are orders of magnitude larger than expected. We discuss several scenarios and tentatively propose that the radio emission could arise in a static ionized atmosphere around a fossil photoevaporated disk

A compact SR light source for x-ray lithography 'AURORA'

International Nuclear Information System (INIS)

Toba, Y.

1990-01-01

A compact synchrotron radiation (SR) light source called AURORA has been developed for industrial use. It is specially designed for X-ray lithography. AURORA consists of a storage ring, injector microtron and SR light beam lines. The storage ring is a superconducting single magnet machine, designed to accelerate a 150 MeV electron beam to 650 MeV and to store as high as 300 mA current. The injector is a racetrack microtron (RTM) producing a pulsed 150 MeV beam. As many as 16 SR light beam channels are available for AURORA. Prototypes of the storage ring and RTM are constructed, and beam commissioning is performed. A hundred and fifty MeV electron beam of a pulsed current 10 μA from the RTM is successfully injected to the ring and accelerated to 600 MeV and 10 mA current stored with a lifetime of more than 20 hours. The half-integer method investigated is shown to work well with the injection efficiency being found to be very high. Improvement of the design is now under way. (N.K.)

A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

Science.gov (United States)

Banks, T. I.; Freedman, S. J.; Wallig, J.; Ybarrolaza, N.; Gando, A.; Gando, Y.; Ikeda, H.; Inoue, K.; Kishimoto, Y.; Koga, M.; Mitsui, T.; Nakamura, K.; Shimizu, I.; Shirai, J.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B. D.; Yoshida, H.; Yoshida, S.; Kozlov, A.; Grant, C.; Keefer, G.; Piepke, A.; Bloxham, T.; Fujikawa, B. K.; Han, K.; Ichimura, K.; Murayama, H.; O`Donnell, T.; Steiner, H. M.; Winslow, L. A.; Dwyer, D. A.; McKeown, R. D.; Zhang, C.; Berger, B. E.; Lane, C. E.; Maricic, J.; Miletic, T.; Batygov, M.; Learned, J. G.; Matsuno, S.; Sakai, M.; Horton-Smith, G. A.; Downum, K. E.; Gratta, G.; Efremenko, Y.; Perevozchikov, O.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Heeger, K. M.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.

2015-01-01

We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable's motion, and the system was controlled via a graphical user interface.

A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

Energy Technology Data Exchange (ETDEWEB)

Banks, T.I., E-mail: tbanks@berkeley.edu [Physics Department, University of California, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Freedman, S.J. [Physics Department, University of California, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Wallig, J.; Ybarrolaza, N. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gando, A.; Gando, Y.; Ikeda, H. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); Inoue, K. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Kishimoto, Y. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); Koga, M. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Mitsui, T. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); Nakamura, K. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Shimizu, I.; Shirai, J.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B.D. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan); and others

2015-01-01

We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable's motion, and the system was controlled via a graphical user interface.

Compact, integrable, and long life time Raman multiline UV-Vis source based on hypocycloid core Kagome HC-PCF

Science.gov (United States)

Chafer, M.; Lekiefs, Q.; Gorse, A.; Beaudou, B.; Debord, B.; Gérôme, F.; Benabid, F.

2017-02-01

Raman-gas filled HC-PCF has proved to be an outstanding Raman-convertor, as illustrated by the generation of more than 5 octaves wide Raman comb using a hydrogen-filled Kagome HC-PCF pumped with high power picosecond-laser, or the generation of multiline Raman-source in the UV-Vis using a very compact system pumped with micro-chip laser. Whilst these demonstrations are promising, a principal challenge for the industrialization of such a Raman source is its lifetime as the H2 diffusion through silica is high enough to leak out from the fiber within only a few months. Here, we report on a HC-PCF based Raman multiline source with a very long life-span. The system consists of hydrogen filled ultra-low loss HC-PCF contained in highly sealed box, coined CombBox, and pumped with a 532 nm micro-chip laser. This combination is a turnkey multiline Raman-source with a "shoe box" size. The CombBox is a robust and compact component that can be integrated and pumped with any common pulsed laser. When pumped with a 32 mW average power and 1 ns frequency-doubled Nd:Yag microchip laser, this Raman-source generates 24 lines spanning from 355 to 745 nm, and a peak power density per line of 260 mW/nm for the strongest lines. Both the output power and the spectrum remained constant over its monitoring duration of more than six months. The spectrum of this multiline laser superimposes with no less than 17 absorption peaks of fluorescent dyes from the Alexa Fluor family used as biological markers.

RF power source for the compact linear collider test facility (CTF3)

CERN Document Server

McMonagle, G; Brown, Peter; Carron, G; Hanni, R; Mourier, J; Rossat, G; Syratchev, I V; Tanner, L; Thorndahl, L

2004-01-01

The CERN CTF3 facility will test and demonstrate many vital components of CLIC (Compact Linear Collider). This paper describes the pulsed RF power source at 2998.55 MHz for the drive-beam accelerator (DBA), which produces a beam with an energy of 150 MeV and a current of 3.5 Amps. Where possible, existing equipment from the LEP preinjector, especially the modulators and klystrons, is being used and upgraded to achieve this goal. A high power RF pulse compression system is used at the output of each klystron, which requires sophisticated RF phase programming on the low level side to achieve the required RF pulse. In addition to the 3 GHz system two pulsed RF sources operating at 1.5 GHz are being built. The first is a wide-band, low power, travelling wave tube (TWT) for the subharmonic buncher (SHB) system that produces a train of "phase coded" subpulses as part of the injector scheme. The second is a high power narrow band system to produce 20 MW RF power to the 1.5 GHz RF deflectors in the delay loop situate...

Focusing and transport of high-intensity multi-MeV proton bunches from a compact laser-driven source

Science.gov (United States)

Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Frydrych, S.; Kroll, F.; Joost, M.; Al-Omari, H.; Blažević, A.; Zielbauer, B.; Hofmann, I.; Bagnoud, V.; Cowan, T. E.; Roth, M.

2013-10-01

Laser ion acceleration provides for compact, high-intensity ion sources in the multi-MeV range. Using a pulsed high-field solenoid, for the first time high-intensity laser-accelerated proton bunches could be selected from the continuous exponential spectrum and delivered to large distances, containing more than 109 particles in a narrow energy interval around a central energy of 9.4 MeV and showing ≤30mrad envelope divergence. The bunches of only a few nanoseconds bunch duration were characterized 2.2 m behind the laser-plasma source with respect to arrival time, energy width, and intensity as well as spatial and temporal bunch profile.

EVN observations of low-luminosity flat-spectrum active galactic nuclei

NARCIS (Netherlands)

Caccianiga, A; Marcha, MJM; Thean, A; Dennett-Thorpe, J

2001-01-01

We present and discuss the results of very-long baseline interferometry (VLBI, EVN) observations of three low-luminosity (P-5GHz <10(25) W Hz(-1)) broad emission line active galactic nuclei (AGNs) carefully selected from a sample of flat-spectrum radio sources (CLASS). Based on the total and the

Search for gamma-ray spectral modulations in Galactic pulsars

Science.gov (United States)

Majumdar, Jhilik; Calore, Francesca; Horns, Dieter

2018-04-01

Well-motivated extensions of the standard model predict ultra-light and fundamental pseudo-scalar particles (e.g., axions or axion-like particles: ALPs). Similarly to the Primakoff-effect for axions, ALPs can mix with photons and consequently be searched for in laboratory experiments and with astrophysical observations. Here, we search for energy-dependent modulations of high-energy gamma-ray spectra that are tell-tale signatures of photon-ALPs mixing. To this end, we analyze the data recorded with the Fermi-LAT from Galactic pulsars selected to have a line of sight crossing spiral arms at a large pitch angle. The large-scale Galactic magnetic field traces the shape of spiral arms, such that a sizable photon-ALP conversion probability is expected for the sources considered. For the nearby Vela pulsar, the energy spectrum is well described by a smooth model spectrum (a power-law with a sub-exponential cut-off) while for the six selected Galactic pulsars, a common fit of the ALPs parameters improves the goodness of fit in comparison to a smooth model spectrum with a significance of 4.6 σ. We determine the most-likely values for mass ma and coupling gaγγ to be ma=(3.6‑0.2 stat.+0.5 stat.± 0.2syst. ) neV and gaγγ=(2.3‑0.4stat.+0.3 stat.± 0.4syst.)× 10‑10 GeV‑1. In the error budget, we consider instrumental effects, scaling of the adopted Galactic magnetic field model (± 20 %), and uncertainties on the distance of individual sources. The best-fit parameters are by a factor of ≈ 3 larger than the current best limit on solar ALPs generation obtained with the CAST helioscope, although known modifications of the photon-ALP mixing in the high density solar environment could provide a plausible explanation for the apparent tension between the helioscope bound and the indication for photon-ALPs mixing reported here.

Simulating deep surveys of the Galactic Plane with the Advanced Gamma-ray Imaging System (AGIS)

Science.gov (United States)

Funk, Stefan; Digel, Seth

2009-05-01

The pioneering survey of the Galactic plane by H.E.S.S., together with the northern complement now underway with VERITAS, has shown the inner Milky Way to be rich in TeV-emitting sources; new source classes have been found among the H.E.S.S. detections and unidentified sources remain. In order to explore optimizations of the design of an Advanced Gamma-ray Imaging System (AGIS)-like instrument for survey science, we constructed a model of the flux and size distributions of Galactic TeV sources, normalized to the H.E.S.S. sources but extrapolated to lower flux levels. We investigated potential outcomes from a survey with the order of magnitude improvement in sensitivity and attendant improvement in angular resolution planned for AGIS. Studies of individual sources and populations found with such a sensitivity survey will advance understanding of astrophysical particle acceleration, source populations, and even high-energy cosmic rays via detection of the low-level TeV diffuse emission in regions of high cosmic-ray densitiy.

The Galactic Distribution of Planets via Spitzer Microlensing Parallax

Science.gov (United States)

Gould, Andrew; Yee, Jennifer; Carey, Sean; Shvartzvald, Yossi

2018-05-01

We will measure the Galactic distribution of planets by obtaining 'microlens parallaxes' of about 200 events, including 3 planetary events, from the comparison of microlens lightcurves observed from Spitzer and Earth, which are separated by >1.5 AU in projection. The proposed observations are part of a campaign that we have conducted with Spitzer since 2014. The planets expected to be identified in this campaign when combined with previous work will yield a first statistically significant measurement of the frequency of planets in the Galactic bulge versus the Galactic disk. As we have demonstrated in three previous programs, the difference in these lightcurves yields both the 'microlens parallax' (ratio of the lens-source relative parallax) to the Einstein radius, and the direction of lens-source relative motion. For planetary events, this measurement directly yields the mass and distance of the planet. This proposal is significantly more sensitive to planets than previous work because it takes advantage of the KMTNet observing strategy that covers >85 sq.deg t >0.4/hr cadence, 24/7 from 3 southern observatories and a alert system KMTNet is implementing for 2019. This same observing program also provides a unique probe of dark objects. It will yield an improved measurement of the isolated-brown-dwarf mass function. Thirteen percent of the observations will specifically target binaries, which will probe systems with dark components (brown dwarfs, neutron stars, black holes) that are difficult or impossible to investigate by other methods. The observations and methods from this work are a test bed for WFIRST microlensing.

Consistency between the luminosity function of resolved millisecond pulsars and the galactic center excess

Energy Technology Data Exchange (ETDEWEB)

Ploeg, Harrison; Gordon, Chris [Department of Physics and Astronomy, Rutherford Building, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand); Crocker, Roland [Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, Cotter Road, Weston Creek (Australia); Macias, Oscar, E-mail: harrison.ploeg@pg.canterbury.ac.nz, E-mail: chris.gordon@canterbury.ac.nz, E-mail: Roland.Crocker@anu.edu.au, E-mail: oscar.macias@vt.edu [Center for Neutrino Physics, Department of Physics, Virginia Tech, 850 West Campus Drive, Blacksburg, VA 24061 (United States)

2017-08-01

Fermi Large Area Telescope data reveal an excess of GeV gamma rays from the direction of the Galactic Center and bulge. Several explanations have been proposed for this excess including an unresolved population of millisecond pulsars (MSPs) and self-annihilating dark matter. It has been claimed that a key discriminant for or against the MSP explanation can be extracted from the properties of the luminosity function describing this source population. Specifically, is the luminosity function of the putative MSPs in the Galactic Center consistent with that characterizing the resolved MSPs in the Galactic disk? To investigate this we have used a Bayesian Markov Chain Monte Carlo to evaluate the posterior distribution of the parameters of the MSP luminosity function describing both resolved MSPs and the Galactic Center excess. At variance with some other claims, our analysis reveals that, within current uncertainties, both data sets can be well fit with the same luminosity function.

A comment on the emission from the Galactic Center as seen by the Fermi telescope

International Nuclear Information System (INIS)

Boyarsky, Alexey; Malyshev, Denys; Ruchayskiy, Oleg

2011-01-01

In the recent paper of Hooper and Goodenough (2010) it was reported that γ-ray emission from the Galactic Center region contains an excess compared to the contributions from the large-scale diffuse emission and known point sources. This excess was argued to be consistent with a signal from annihilation of Dark Matter with a power law density profile. We reanalyze the Fermi data and find instead that it is consistent with the “standard model” of diffuse emission and of known point sources. The main reason for the discrepancy with the interpretation of Hooper and Goodenough (2010) is different (as compared to the previous works) spectrum of the point source at the Galactic Center assumed by Hooper and Goodenough (2010) . We discuss possible reasons for such an interpretation.

Local Swift-BAT active galactic nuclei prefer circumnuclear star formation

Science.gov (United States)

Lutz, D.; Shimizu, T.; Davies, R. I.; Herrera-Camus, R.; Sturm, E.; Tacconi, L. J.; Veilleux, S.

2018-01-01

We use Herschel data to analyze the size of the far-infrared 70 μm emission for z BAT selected active galactic nuclei (AGN), and 515 comparison galaxies that are not detected by BAT. For modest far-infrared luminosities 8.5 BAT hosts that is only half that of comparison galaxies of same far-infrared luminosity. The result mostly reflects a more compact distribution of star formation (and hence gas) in the AGN hosts, but compact AGN heated dust may contribute in some extremely AGN dominated systems. Our findings are in support of an AGN-host coevolution where accretion onto the central black hole and star formation are fed from the same gas reservoir, with more efficient black hole feeding if that reservoir is more concentrated. The significant scatter in the far-infrared sizes emphasizes that we are mostly probing spatial scales much larger than those of actual accretion, and that rapid accretion variations can smear the distinction between the AGN and comparison categories. Large samples are hence needed to detect structural differences that favor feeding of the black hole. No size difference between AGN host and comparison galaxies is observed at higher far-infrared luminosities log(LFIR [L⊙]) > 10.5 (star formation rates ≳6 M⊙ yr-1), possibly because these are typically reached in more compact regions. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A9

X-ray photoelectron microscope with a compact x-ray source generated by line-focused laser irradiation

International Nuclear Information System (INIS)

Yamaguchi, N.; Okamoto, Y.; Hara, T.; Takahashi, Z.; Nishimura, Y.; Sakata, A.; Watanabe, K.; Azuma, H.

2004-01-01

Full text: A laboratory-sized microscopic system of x-ray photoelectrons has been developing using a compact x-ray source produced by line-focused laser irradiation. The system is a scanning type photoelectron microscope where x-ray beam is micro-focused via a Schwartzschild optics. A compact laser-plasma x-ray source has been developed with a YAG laser system, a line-focus lens system, a tape-target driving system and a debris prevention system, that was operated at repetition rate of 10 Hz or 50 Hz. X-rays were delivered along line plasma whose length was 0.6 to 11 mm with higher intensity than that from a point-focused source. Because the transition line of Al V (13.1 nm) was prominent in the soft x-ray spectrum when the Al tape target irradiated at the lower power density of 10 11 W/cm 2 , the 13.1 nm x-ray was used as an excitation source. The Schwartzschild optics was set on the beamline at a distance about 1 m from the source, which was coated with Mo/Si multilayers for 13.1 nm x-ray. The designed demagnification is 224 that was confirmed in the previous experiment. Therefore, an x-ray micro spot of sub-micron size can be formed on a sample surface when the source size is less than about 0.2 mm. Samples were set on a two-axis high-precision piezo stage mounted to a four-axis manipulator. The electron energy analyzer was a spherical capacitor analyzer with mean diameter of 279.4 mm. The electron detector was a microchannel plate (MCP) with a phosphor screen and the optical image of electrons on the exit plane of the analyzer was taken and recorded by using an ultra low dark noise CCD camera, that was suited for detection of vast photoelectrons excited by x-ray pulse of ns-order duration. We performed spatial resolution test measurements by using a GaAs wafer coated with photo-resist that formed a stripe pattern. The spatial resolution less than 3 micron has been obtained from the variation of As 3d electron intensity along the position of the GaAs sample

Research and development of a compact fusion neutron source for humanitarian landmine detection

International Nuclear Information System (INIS)

Yoshikawa, K.; Masuda, K.; Yamamoto, Y.; Takamatsu, T.; Toku, H.; Nagasaki, K.; Hotta, E.; Yamauchi, K.; Ohnishi, M.; Osawa, H.

2005-01-01

Research and development of the advanced anti-personnel landmine detection system by using a compact discharge-type D-D fusion neutron source called IECF (Inertial-Electrostatic Confinement Fusion) are described. Landmines are to be identified through increased backscattering of neutrons by the hydrogen atoms, and specific-energy capture γ-ray emission by hydrogen and nitrogen atoms with thermalized neutrons in the landmine explosives. For this purpose, improvements of the IECF device were studied for drastic enhancement of neutron production rates of more than 10 8 n/s in pulsed operation including R and D of robust power sources, as well as analyses of envisaged detection system with multi-sensors in parallel in order to show promising and practical features of this detection system for humanitarian landmine detection, particularly, in the aridic, or dry Afghanistan deserted area, where the soil moisture remains between 3-8%, which eventually enables effectively detection of hydrogen anomaly inherent in the landmine explosives. In this paper, improvements of the IECF are focused to be described. (author)

The diversity of neutron stars: Nearby thermally emitting neutron stars and the compact central objects in supernova remnants

Science.gov (United States)

Kaplan, David L.

Neutron stars are invaluable tools for exploring stellar death, the physics of ultra-dense matter, and the effects of extremely strong magnetic fields. The observed population of neutron stars is dominated by the > 1000 radio pulsars, but there are distinct sub-populations that, while fewer in number, can have significant impact on our understanding of the issues mentioned above. These populations are the nearby isolated neutron stars discovered by ROSAT, and the central compact objects in supernova remnants. The studies of both of these populations have been greatly accelerated in recent years through observations with the Chandra X-ray Observatory and the XMM-Newton telescope. First, we discuss radio, optical, and X-ray observations of the nearby neutron stars aimed at determining their relation to the Galactic neutron star population and at unraveling their complex physical processes by determining the basic astronomical parameters that define the population -- instances, ages, and magnetic fields -- the uncertainties in which limit any attempt to derive basic physical parameters for these objects. We conclude that these sources are 10^6 year-old cooling neutron stars with magnetic fields above 10^13 G. Second, we describe the hollow supernova remnant problem: why many of the supernova remnants in the Galaxy have no indication central neutron stars. We have undertaken an X-ray census of neutron stars in a volume-limited sample of Galactic supernova remnants, and from it conclude that either many supernovae do not produce neutron stars contrary to expectation, or that neutron stars can have a wide range in cooling behavior that makes many sources disappear from the X-ray sky.

A Chandra Observation of the Ultraluminous Infrared Galaxy IRAS 19254-7245 (The Superantennae): X-Ray Emission from the Compton-Thick Active Galactic Nucleus and the Diffuse Starburst

Science.gov (United States)

Jia, Jianjun; Ptak, Andrew; Heckman, Timothy M.; Braito, Valentina; Reeves, James

2012-01-01

We present a Chandra observation of IRAS 19254-7245, a nearby ultraluminous infrared galaxy also known as the Superantennae. The high spatial resolution of Chandra allows us to disentangle for the first time the diffuse starburst (SB) emission from the embedded Compton-thick active galactic nucleus (AGN) in the southern nucleus. No AGN activity is detected in the northern nucleus. The 2-10 keV spectrum of the AGN emission is fitted by a flat power law (TAU = 1.3) and an He-like Fe Kalpha line with equivalent width 1.5 keV, consistent with previous observations. The Fe K line profile could be resolved as a blend of a neutral 6.4 keV line and an ionized 6.7 keV (He-like) or 6.9 keV (H-like) line. Variability of the neutral line is detected compared with the previous XMM-Newton and Suzaku observations, demonstrating the compact size of the iron line emission. The spectrum of the galaxy-scale extended emission excluding the AGN and other bright point sources is fitted with a thermal component with a best-fit kT of approximately 0.8 keV. The 2-10 keV luminosity of the extended emission is about one order of magnitude lower than that of the AGN. The basic physical and structural properties of the extended emission are fully consistent with a galactic wind being driven by the SB. A candidate ultraluminous X-ray source is detected 8 south of the southern nucleus. The 0.3 - 10 keV luminosity of this off-nuclear point source is approximately 6 x 10(exp 40) erg per second if the emission is isotropic and the source is associated with the Superantennae.

RADIO AND MID-INFRARED PROPERTIES OF COMPACT STARBURSTS: DISTANCING THEMSELVES FROM THE MAIN SEQUENCE

Energy Technology Data Exchange (ETDEWEB)

Murphy, E. J. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Stierwalt, S.; Armus, L. [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States); Condon, J. J. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Evans, A. S., E-mail: emurphy@obs.carnegiescience.edu [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States)

2013-05-01

We investigate the relationship between 8.44 GHz brightness temperatures and 1.4 to 8.44 GHz radio spectral indices with 6.2 {mu}m polycyclic aromatic hydrocarbon (PAH) emission and 9.7 {mu}m silicate absorption features for a sample of 36 local luminous and ultraluminous infrared galaxies. We find that galaxies having small 6.2 {mu}m PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44 GHz brightness temperatures are also identified as AGN via their small 6.2 {mu}m PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44 GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations additionally suggest that the dust obscuration in these galaxies must largely be coming from the vicinity of the compact starburst itself, and is not distributed throughout the (foreground) disk of the galaxy. Finally, we investigate the location of these infrared-bright systems relative to the main sequence (star formation rate versus stellar mass) of star-forming galaxies in the local universe. We find that the radio spectral indices of galaxies flatten with increasing distance above the main sequence, or in other words, with increasing specific star formation rate. This indicates that galaxies located above the main sequence, having high specific star formation rates, are typically compact starbursts hosting deeply embedded star formation that becomes more optically thick in the radio and infrared with increased distance above the main sequence.

Small Galactic H II regions. II. The molecular clouds and star formation

International Nuclear Information System (INIS)

Hunter, D.A.; Thronson, H.A. Jr.; Wilton, C.

1990-01-01

CO maps of molecular clouds associated with 11 small Galactic H II regions are presented and compared with IR images obtained by IRAS. The molecular masses of the clouds are computed and compared with the masses of the stellar content. The mapped clouds have masses of 1000-60,000 solar and are typical of the more numerous, smaller Galactic molecular clouds. All of the clouds have recently made massive OB stars, and many have complex spatial and kinematic structures. The coincidence of IRAS sources and CO peaks suggests that many of the clouds have sites of star formation other than the optically visible H II region. Star-formation efficiencies are uncertain, with values for the clouds ranging from 0.02 to 0.6 with an average value of 0.2. There is no trend of the upper stellar mass limit with Galactic radius and with molecular cloud mass. 53 refs

TEV GAMMA-RAY OBSERVATIONS OF THE GALACTIC CENTER RIDGE BY VERITAS

Energy Technology Data Exchange (ETDEWEB)

Archer, A.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Bird, R.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Buchovecky, M. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cardenzana, J. V; Eisch, J. D. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Chen, X. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm (Germany); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Feng, Q.; Finley, J. P. [Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States); Fleischhack, H. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Flinders, A. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Fortson, L., E-mail: asmith44@umd.edu [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); and others

2016-04-20

The Galactic Center ridge has been observed extensively in the past by both GeV and TeV gamma-ray instruments revealing a wealth of structure, including a diffuse component and the point sources G0.9+0.1 (a composite supernova remnant) and Sgr A* (believed to be associated with the supermassive black hole located at the center of our Galaxy). Previous very high energy (VHE) gamma-ray observations with the H.E.S.S. experiment have also detected an extended TeV gamma-ray component along the Galactic plane in the >300 GeV gamma-ray regime. Here we report on observations of the Galactic Center ridge from 2010 to 2014 by the VERITAS telescope array in the >2 TeV energy range. From these observations we (1) provide improved measurements of the differential energy spectrum for Sgr A* in the >2 TeV gamma-ray regime, (2) provide a detection in the >2 TeV gamma-ray emission from the composite SNR G0.9+0.1 and an improved determination of its multi-TeV gamma-ray energy spectrum, and (3) report on the detection of VER J1746-289, a localized enhancement of >2 TeV gamma-ray emission along the Galactic plane.

Comparison of the distribution of galactic γ-radiation and radio synchrotron radiation

International Nuclear Information System (INIS)

Haslam, C.G.T.; Stoffel, H.; Kearsey, S.; Osborne, J.L.; Phillipps, S.

1981-01-01

The new all-sky survey of continuum radio emission at 408 MHz of Haslam et al. (1981) is used to compare the distribution of radio emission in a band along the galactic equator for b 0 , but a longer tail than a Gaussian, for the combined data from 70 MeV-5 GeV. This has been used to convolve the 408 MHz data, and to produce a contour map and the cuts and averages corresponding to those given by Mayer-Hasselwander. The average intensities along the galactic plane for b 0 are given. The latitude profiles show that in three dimensions the gamma-ray and synchrotron emissivities are not proportional. However, in the Galactic plane the two emissivities can be in approximately constant ratio although there seems to be more structure in the gamma-ray emission. This implies that the square of the galactic magnetic field, B 2 is proportional to gas density under the right conditions. If the emission were dominated by discrete sources their number density would have to follow closely the product of cosmic ray density and B 2 . (U.K.)

The Galactic Center View with Simbol-X

Science.gov (United States)

Raimondi, L.; Malaguti, G.; Angelini, L.; Cappi, M.; Grandi, P.; Palumbo, G. G. C.; Puccetti, S.

2009-05-01

The nature of the hard X-ray emission above 3 keV of the Galactic Centre (GC) is still source of controversy. Recent observations with Chandra are consistent with either a population of discrete sources or with a diffuse non thermal emission or, most likely, a combination of the two. The Simbol-X mission will be equipped with a grazing incident telescope imaging up to ~80 keV, providing an improvement of three orders of magnitude in sensitivity and angular resolution compared with the instruments that have operated so far above 10 keV. This capability will enable to directly disentangle between the discrete source versus the diffuse emission scenarios. This is demonstrated by the Simbol-X simulations of the GC shown here, where the input model includes a list of both diffuse and point sources (both resolved and unresolved) using the input spectrum observed with presently operating X-ray telescopes.

Compact range for variable-zone measurements

Science.gov (United States)

Burnside, Walter D.; Rudduck, Roger C.; Yu, Jiunn S.

1988-08-02

A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector.

Focusing and transport of high-intensity multi-MeV proton bunches from a compact laser-driven source

Directory of Open Access Journals (Sweden)

S. Busold

2013-10-01

Full Text Available Laser ion acceleration provides for compact, high-intensity ion sources in the multi-MeV range. Using a pulsed high-field solenoid, for the first time high-intensity laser-accelerated proton bunches could be selected from the continuous exponential spectrum and delivered to large distances, containing more than 10^{9} particles in a narrow energy interval around a central energy of 9.4 MeV and showing ≤30  mrad envelope divergence. The bunches of only a few nanoseconds bunch duration were characterized 2.2 m behind the laser-plasma source with respect to arrival time, energy width, and intensity as well as spatial and temporal bunch profile.

THE COMPACT, TIME-VARIABLE RADIO SOURCE PROJECTED INSIDE W3(OH): EVIDENCE FOR A PHOTOEVAPORATED DISK?

Energy Technology Data Exchange (ETDEWEB)

Dzib, Sergio A.; Rodriguez-Garza, Carolina B.; Rodriguez, Luis F.; Kurtz, Stan E.; Loinard, Laurent; Zapata, Luis A.; Lizano, Susana, E-mail: s.dzib@crya.unam.mx [Centro de Radiostronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia 58089 (Mexico)

2013-08-01

We present new Karl G. Jansky Very Large Array (VLA) observations of the compact ({approx}0.''05), time-variable radio source projected near the center of the ultracompact H II region W3(OH). The analysis of our new data as well as of VLA archival observations confirms the variability of the source on timescales of years and for a given epoch indicates a spectral index of {alpha} = 1.3 {+-} 0.3 (S{sub {nu}}{proportional_to}{nu}{sup {alpha}}). This spectral index and the brightness temperature of the source ({approx}6500 K) suggest that we are most likely detecting partially optically thick free-free radiation. The radio source is probably associated with the ionizing star of W3(OH), but an interpretation in terms of an ionized stellar wind fails because the detected flux densities are orders of magnitude larger than expected. We discuss several scenarios and tentatively propose that the radio emission could arise in a static ionized atmosphere around a fossil photoevaporated disk.

A Compact 5 MeV S-Band Electron Linac Based X-Ray Source for Industrial Radiography

CERN Document Server

Auditore, Lucrezia; De Pasquale, Domenico; Emanuele, Umberto; Italiano, Antonio; Trifirò, Antonio; Trimarchi, Marina

2005-01-01

A compact and reliable X-ray source, based on a 5 MeV, 1 kW, S-band electron linac, has been set up at the Dipartimento di Fisica, Universit\\'a di Messina. This source, coupled with a GOS scintillator screen and a CCD camera, represents an innovative transportable system for industrial radiography and X-ray tomography. Optimization of the parameters influencing the e-gamma conversion and the X-ray beam characteristics have been studied by means of the MCNP-4C2 code. The converter choice is the result of the study of the e-gamma conversion performances for different materials and materials thicknesses. Also the converter position with respect to the linac exit window was studied. The chosen converter consists in a Ta-Cu target inserted close to the linac window. The Cu layer acts as a filter both on the electrons from the source and on the low energy X-rays. The X-ray beam angular profile was studied by means of GafChromic films with and without collimation. In the final source project, a collimation system pr...

Dark matter and pulsar model constraints from Galactic center Fermi/LAT γ-ray observations

Science.gov (United States)

Gordon, Chris; Macias, Oscar

2014-05-01

Employing Fermi/LAT γ-ray observations, several independent groups have found excess extended γ-ray emission at the Galactic center (GC). Both, annihilating dark matter (DM) or a population of ~ 103 unresolved millisecond pulsars (MSPs) are regarded as well motivated possible explanations. However, there is significant uncertainties in the diffuse Galactic background at the GC. We have performed a revaluation of these two models for the extended γ-ray source at the GC by accounting for the systematic uncertainties of the Galactic diffuse emission model. We also marginalize over point source and diffuse background parameters in the region of interest. We show that the excess emission is significantly more extended than a point source. We find that the DM (or pulsar population) signal is larger than the systematic errors and therefore proceed to determine the sectors of parameter space that provide an acceptable fit to the data. We found that a population of several thousand MSPs with parameters consistent with the average spectral shape of Fermi/LAT measured MSPs was able to fit the GC excess emission. For DM, we found that a pure τ+τ- annihilation channel is not a good fit to the data. But a mixture of τ+τ- and bb with a of order the thermal relic value and a DM mass of around 20 to 60 GeV provides an adequate fit.

The transition from galactic to extragalactic cosmic rays

Energy Technology Data Exchange (ETDEWEB)

Stanev, Todor [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

2007-06-15

We discuss the region of transition between galactic and extragalactic cosmic rays. The exact shapes and compositions of these two components contain information about important parameters of powerful astrophysical sources and the conditions in extragalactic space. Several types of experimental data, including the exact shape of the ultrahigh energy cosmic rays, their chemical composition and their anisotropy, and the fluxes of cosmogenic neutrinos have to be included in the solution of this problem.

ASGARD: A LARGE SURVEY FOR SLOW GALACTIC RADIO TRANSIENTS. I. OVERVIEW AND FIRST RESULTS

Energy Technology Data Exchange (ETDEWEB)

Williams, Peter K. G.; Bower, Geoffrey C.; Croft, Steve; Keating, Garrett K.; Law, Casey J.; Wright, Melvyn C. H., E-mail: pwilliams@astro.berkeley.edu [Department of Astronomy, B-20 Hearst Field Annex 3411, University of California, Berkeley, CA 94720-3411 (United States)

2013-01-10

Searches for slow radio transients and variables have generally focused on extragalactic populations, and the basic parameters of Galactic populations remain poorly characterized. We present a large 3 GHz survey performed with the Allen Telescope Array (ATA) that aims to improve this situation: ASGARD, the ATA Survey of Galactic Radio Dynamism. ASGARD observations spanned two years with weekly visits to 23 deg{sup 2} in two fields in the Galactic plane, totaling 900 hr of integration time on science fields and making it significantly larger than previous efforts. The typical blind unresolved source detection limit was 10 mJy. We describe the observations and data analysis techniques in detail, demonstrating our ability to create accurate wide-field images while effectively modeling and subtracting large-scale radio emission, allowing standard transient-and-variability analysis techniques to be used. We present early results from the analysis of two pointings: one centered on the microquasar Cygnus X-3 and one overlapping the Kepler field of view (l = 76 Degree-Sign , b = +13. Degree-Sign 5). Our results include images, catalog statistics, completeness functions, variability measurements, and a transient search. Out of 134 sources detected in these pointings, the only compellingly variable one is Cygnus X-3, and no transients are detected. We estimate number counts for potential Galactic radio transients and compare our current limits to previous work and our projection for the fully analyzed ASGARD data set.

Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW

CERN Document Server

Kazarezov, Ivan; Balakin, Vladimir E; Bryazgin, Alex; Bulatov, Alexandre; Glazkov, Ivan; Kokin, Evgeny; Krainov, Gennady; Kuznetsov, Gennady I; Molokoedov, Andrey; Tuvik, Alfred

2005-01-01

The paper describes a compact electron beam source with average electron energy of 200 keV. The source operates with pulse power up to 2 MW under average power not higher than 2 kW, pulsed beam current up to 10 A, pulse duration up to 2 mks, and repetition rate up to 5 kHz. The electron beam is extracted through aluminium-beryllium alloy foil. The pulse duration and repetition rate can be changed from control desk. High-voltage generator for the source with output voltage up to 220 kV is realized using the voltage-doubling circuit which consists of 30 sections. The insulation type - gas, SF6 under pressure of 8 atm. The cooling of the foil supporting tubes is provided by a water-alcohol mixture from an independent source. The beam output window dimensions are 180?75 mm, the energy spread in the beam +10/-30%, the source weight is 80 kg.

A low-latitude southern atlas of galactic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Poeppel, W G.L. [Instituto Argentino de Radioastronomia, Villa Elisa, Buenos Aires, Argentina; Olano, C A [Rio Grande do Sul, Universidade Federal, Porto Alegre, Brazil

1979-01-01

An atlas of 21 cm line profiles is described, which was made using a 30 m radio telescope with angular resolution of 0.5 deg, to study the properties of the low latitude H I gas excluding the complexity of the galactic plane. The results of the atlas itself are presented in two sets of diagrams: average profiles for each point, and contour maps. Analyses of the data have centered on an anomalous velocity cloud near galactic longitude (1) equals 349 deg, and latitude (b) equals plus 3 deg, strong kinematic asymmetries of the interstellar gas in the region of 1 between 348 and 12 deg and b between plus 3 and plus 17 deg, with positive radial velocities predominant, caused by a very intense source seemingly identical to Lindblad's (1967) feature A, and a comparative study of optical and radioastronomical data of the section of Gould's belt from 1 equals 300 to 12 deg.

The Gaia-ESO Survey: Lithium enrichment histories of the Galactic thick and thin disc

Science.gov (United States)

Fu, X.; Romano, D.; Bragaglia, A.; Mucciarelli, A.; Lind, K.; Delgado Mena, E.; Sousa, S. G.; Randich, S.; Bressan, A.; Sbordone, L.; Martell, S.; Korn, A. J.; Abia, C.; Smiljanic, R.; Jofré, P.; Pancino, E.; Tautvaišienė, G.; Tang, B.; Magrini, L.; Lanzafame, A. C.; Carraro, G.; Bensby, T.; Damiani, F.; Alfaro, E. J.; Flaccomio, E.; Morbidelli, L.; Zaggia, S.; Lardo, C.; Monaco, L.; Frasca, A.; Donati, P.; Drazdauskas, A.; Chorniy, Y.; Bayo, A.; Kordopatis, G.

2018-02-01

Lithium abundance in most of the warm metal-poor main sequence stars shows a constarnt plateau (A(Li) 2.2 dex) and then the upper envelope of the lithium vs. metallicity distribution increases as we approach solar metallicity. Meteorites, which carry information about the chemical composition of the interstellar medium (ISM) at the solar system formation time, show a lithium abundance A(Li) 3.26 dex. This pattern reflects the Li enrichment history of the ISM during the Galaxy lifetime. After the initial Li production in big bang nucleosynthesis, the sources of the enrichment include asymptotic giant branch (AGB) stars, low-mass red giants, novae, type II supernovae, and Galactic cosmic rays. The total amount of enriched Li is sensitive to the relative contribution of these sources. Thus different Li enrichment histories are expected in the Galactic thick and thin disc. We investigate the main sequence stars observed with UVES in Gaia-ESO Survey iDR4 catalogue and find a Li-anticorrelation independent of [Fe/H], Teff, and log(g). Since in stellar evolution different α enhancements at the same metallicity do not lead to a measurable Li abundance change, the anticorrelation indicates that more Li is produced during the Galactic thin disc phase than during the Galactic thick disc phase. We also find a correlation between the abundance of Li and s-process elements Ba and Y, and they both decrease above the solar metallicity, which can be explained in the framework of the adopted Galactic chemical evolution models. The full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A38

A compact electron gun using field emitter array

International Nuclear Information System (INIS)

Asakawa, M.R.; Ikeda, A.; Miyabe, N.; Yamaguchi, S.; Kusaba, M.; Tsunawaki, Y.

2008-01-01

A compact electron gun using field emitter array has been developed. With a simple triode configuration consisting of FEA, mid-electrode and anode electrode, the electron gun produces a parallel beam with a diameter of 0.5 mm. This electron gun is applicable for compact radiation sources such as Cherenkov free-electron lasers

RESOLVING THE GEOMETRY OF THE INNERMOST RELATIVISTIC JETS IN ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Algaba, J. C.; Lee, S. S. [Korea Astronomy and Space Science Institute, 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Nakamura, M.; Asada, K., E-mail: algaba@kasi.re.kr [Academia Sinica, Institute of Astronomy and Astrophysics, 11F of Astronomy-Mathematics Building, AS/NTU. No.1, Section 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C (China)

2017-01-01

In the current paradigm, it is believed that the compact VLBI radio core of radio-loud active galactic nuclei (AGNs) represents the innermost upstream regions of relativistic outflows. These regions of AGN jets have generally been modeled by a conical outflow with a roughly constant opening angle and flow speed. Nonetheless, some works suggest that a parabolic geometry would be more appropriate to fit the high energy spectral distribution properties and it has been recently found that, at least in some nearby radio galaxies, the geometry of the innermost regions of the jet is parabolic. We compile here multi-frequency core sizes of archival data to investigate the typically unresolved upstream regions of the jet geometry of a sample of 56 radio-loud AGNs. Data combined from the sources considered here are not consistent with the classic picture of a conical jet starting in the vicinity of the super-massive black hole (SMBH), and may exclude a pure parabolic outflow solution, but rather suggest an intermediate solution with quasi-parabolic streams, which are frequently seen in numerical simulations. Inspection of the large opening angles near the SMBH and the range of the Lorentz factors derived from our results support our analyses. Our result suggests that the conical jet paradigm in AGNs needs to be re-examined by millimeter/sub-millimeter VLBI observations.

Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre.

Science.gov (United States)

Doeleman, Sheperd S; Weintroub, Jonathan; Rogers, Alan E E; Plambeck, Richard; Freund, Robert; Tilanus, Remo P J; Friberg, Per; Ziurys, Lucy M; Moran, James M; Corey, Brian; Young, Ken H; Smythe, Daniel L; Titus, Michael; Marrone, Daniel P; Cappallo, Roger J; Bock, Douglas C-J; Bower, Geoffrey C; Chamberlin, Richard; Davis, Gary R; Krichbaum, Thomas P; Lamb, James; Maness, Holly; Niell, Arthur E; Roy, Alan; Strittmatter, Peter; Werthimer, Daniel; Whitney, Alan R; Woody, David

2008-09-04

The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation. Sagittarius A* (Sgr A*), the compact source of radio, infrared and X-ray emission at the centre of the Milky Way, is the closest example of this phenomenon, with an estimated black hole mass that is 4,000,000 times that of the Sun. A long-standing astronomical goal is to resolve structures in the innermost accretion flow surrounding Sgr A*, where strong gravitational fields will distort the appearance of radiation emitted near the black hole. Radio observations at wavelengths of 3.5 mm and 7 mm have detected intrinsic structure in Sgr A*, but the spatial resolution of observations at these wavelengths is limited by interstellar scattering. Here we report observations at a wavelength of 1.3 mm that set a size of 37(+16)(-10) microarcseconds on the intrinsic diameter of Sgr A*. This is less than the expected apparent size of the event horizon of the presumed black hole, suggesting that the bulk of Sgr A* emission may not be centred on the black hole, but arises in the surrounding accretion flow.

Widespread rotationally hot hydronium ion in the galactic interstellar medium

International Nuclear Information System (INIS)

Lis, D. C.; Phillips, T. G.; Schilke, P.; Comito, C.; Higgins, R.

2014-01-01

We present new Herschel observations of the (6,6) and (9,9) inversion transitions of the hydronium ion toward Sagittarius B2(N) and W31C. Sensitive observations toward Sagittarius B2(N) show that the high, ∼500 K, rotational temperatures characterizing the population of the highly excited metastable H 3 O + rotational levels are present over a wide range of velocities corresponding to the Sagittarius B2 envelope, as well as the foreground gas clouds between the Sun and the source. Observations of the same lines toward W31C, a line of sight that does not intersect the Central Molecular Zone but instead traces quiescent gas in the Galactic disk, also imply a high rotational temperature of ∼380 K, well in excess of the kinetic temperature of the diffuse Galactic interstellar medium. While it is plausible that some fraction of the molecular gas may be heated to such high temperatures in the active environment of the Galactic center, characterized by high X-ray and cosmic-ray fluxes, shocks, and high degree of turbulence, this is unlikely in the largely quiescent environment of the Galactic disk clouds. We suggest instead that the highly excited states of the hydronium ion are populated mainly by exoergic chemical formation processes and the temperature describing the rotational level population does not represent the physical temperature of the medium. The same arguments may be applicable to other symmetric top rotors, such as ammonia. This offers a simple explanation of the long-standing puzzle of the presence of a pervasive, hot molecular gas component in the central region of the Milky Way. Moreover, our observations suggest that this is a universal process not limited to the active environments associated with galactic nuclei.

THE VLA SURVEY OF CHANDRA DEEP FIELD SOUTH. V. EVOLUTION AND LUMINOSITY FUNCTIONS OF SUB-MILLIJANSKY RADIO SOURCES AND THE ISSUE OF RADIO EMISSION IN RADIO-QUIET ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

Padovani, P.; Mainieri, V.; Rosati, P.; Miller, N.; Kellermann, K. I.; Tozzi, P.

2011-01-01

We present the evolutionary properties and luminosity functions of the radio sources belonging to the Chandra Deep Field South Very Large Array survey, which reaches a flux density limit at 1.4 GHz of 43 μJy at the field center and redshift ∼5 and which includes the first radio-selected complete sample of radio-quiet active galactic nuclei (AGNs). We use a new, comprehensive classification scheme based on radio, far- and near-IR, optical, and X-ray data to disentangle star-forming galaxies (SFGs) from AGNs and radio-quiet from radio-loud AGNs. We confirm our previous result that SFGs become dominant only below 0.1 mJy. The sub-millijansky radio sky turns out to be a complex mix of SFGs and radio-quiet AGNs evolving at a similar, strong rate; non-evolving low-luminosity radio galaxies; and declining radio powerful (P ∼> 3 x 10 24 W Hz -1 ) AGNs. Our results suggest that radio emission from radio-quiet AGNs is closely related to star formation. The detection of compact, high brightness temperature cores in several nearby radio-quiet AGNs can be explained by the coexistence of two components, one non-evolving and AGN related and one evolving and star formation related. Radio-quiet AGNs are an important class of sub-millijansky sources, accounting for ∼30% of the sample and ∼60% of all AGNs, and outnumbering radio-loud AGNs at ∼< 0.1 mJy. This implies that future, large area sub-millijansky surveys, given the appropriate ancillary multiwavelength data, have the potential of being able to assemble vast samples of radio-quiet AGNs, bypassing the problems of obscuration that plague the optical and soft X-ray bands.

Investigation of pressing of molybdenum powder compacts

International Nuclear Information System (INIS)

Mymrin, S.A.; Kuznetsov, V.Eh.; Yampol'skij, M.L.; Leonov, S.A.; Mikhridinov, R.M.; Korzukhin, V.A.

1990-01-01

Results of an experimental investigation into pressing of compacts of MCh type molybdenum powders using the industrial equipment are presented. To measure the density of powder molybdenum billets a radioisotopic density meter with cesium-137 is used as radioactive gamma radiation source. The dependence of the produced billet density on the specific compacting pressure at different values of the powder bulk density is ascertained

Simulating Galaxies and Active Galactic Nuclei in the LSST Image Simulation Effort

NARCIS (Netherlands)

Pizagno II, Jim; Ahmad, Z.; Bankert, J.; Bard, D.; Connolly, A.; Chang, C.; Gibson, R. R.; Gilmore, K.; Grace, E.; Hannel, M.; Jernigan, J. G.; Jones, L.; Kahn, S. M.; Krughoff, S. K.; Lorenz, S.; Marshall, S.; Shmakova, S. M.; Sylvestri, N.; Todd, N.; Young, M.

We present an extragalactic source catalog, which includes galaxies and Active Galactic Nuclei, that is used for the Large Survey Synoptic Telescope Imaging Simulation effort. The galaxies are taken from the De Lucia et. al. (2006) semi-analytic modeling (SAM) of the Millennium Simulation. The LSST

DNA strand breaks induced by soft X-ray pulses from a compact laser plasma source

Science.gov (United States)

Adjei, Daniel; Wiechec, Anna; Wachulak, Przemyslaw; Ayele, Mesfin Getachew; Lekki, Janusz; Kwiatek, Wojciech M.; Bartnik, Andrzej; Davídková, Marie; Vyšín, Luděk; Juha, Libor; Pina, Ladislav; Fiedorowicz, Henryk

2016-03-01

Application of a compact laser plasma source of soft X-rays in radiobiology studies is demonstrated. The source is based on a laser produced plasma as a result of irradiation of a double-stream gas puff target with nanosecond laser pulses from a commercially available Nd:YAG laser. The source allows irradiation of samples with soft X-ray pulses in the "water window" spectral range (wavelength: 2.3-4.4 nm; photon energy: 280-560 eV) in vacuum or a helium atmosphere at very high-dose rates and doses exceeding the kGy level. Single-strand breaks (SSB) and double-strand breaks (DBS) induced in DNA plasmids pBR322 and pUC19 have been measured. The different conformations of the plasmid DNA were separated by agarose gel electrophoresis. An exponential decrease in the supercoiled form with an increase in linear and relaxed forms of the plasmids has been observed as a function of increasing photon fluence. Significant difference between SSB and DSB in case of wet and dry samples was observed that is connected with the production of free radicals in the wet sample by soft X-ray photons and subsequent affecting the plasmid DNA. Therefore, the new source was validated to be useful for radiobiology experiments.

Cosmic ray acceleration by large scale galactic shocks

International Nuclear Information System (INIS)

Cesarsky, C.J.; Lagage, P.O.

1987-01-01

The mechanism of diffusive shock acceleration may account for the existence of galactic cosmic rays detailed application to stellar wind shocks and especially to supernova shocks have been developed. Existing models can usually deal with the energetics or the spectral slope, but the observed energy range of cosmic rays is not explained. Therefore it seems worthwhile to examine the effect that large scale, long-lived galactic shocks may have on galactic cosmic rays, in the frame of the diffusive shock acceleration mechanism. Large scale fast shocks can only be expected to exist in the galactic halo. We consider three situations where they may arise: expansion of a supernova shock in the halo, galactic wind, galactic infall; and discuss the possible existence of these shocks and their role in accelerating cosmic rays

Structure and content of the galaxy and galactic gamma rays

International Nuclear Information System (INIS)

1976-01-01

The conference included papers on γ-ray pulsars, galactic diffuse flux and surveys, radio surveys of external galaxies, galactic distribution of pulsars, and galactic gamma emission. Galactic structure drawing on all branches of galactic astronomy is discussed. New and unpublished material is included

The present status of a compact synchrotron radiation source LUNA of IHI

International Nuclear Information System (INIS)

Marushita, Motoharu; Oishi, Masaya; Takahashi, Mitsuyuki; Komatsu, Takahito; Mandai, Shinichi

1993-01-01

Synchrotron radiation is expected to apply to many fields of science and industry and we are specially interested in availability of SR for X-ray lithography. This paper presents the characteristics, the design parameters, the features and current status of LUNA. Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI) has developed a compact synchrotron radiation source 'LUNA' for lithography and has successfully stored beam current at full energy. LUNA consists of a 45 MeV linear accelerator as an electron injector and an 800 MeV synchrotron as a storage ring. The construction of LUNA has been completed in April 1989 at IHI Tsuchiura facility near Tsukuba. Synchrotron Radiation was first observed at December 1989. The design goal, which is to store beam current of 50 mA with the beam lifetime of over 30 minutes, has been successfully achieved in March 1991. At present the stored beam current is 80 mA with the beam lifetime of over 5 hours. (author)

Structure and content of the galaxy and galactic gamma rays

Energy Technology Data Exchange (ETDEWEB)

1976-01-01

The conference included papers on ..gamma..-ray pulsars, galactic diffuse flux and surveys, radio surveys of external galaxies, galactic distribution of pulsars, and galactic gamma emission. Galactic structure drawing on all branches of galactic astronomy is discussed. New and unpublished material is included. (JFP)

Portable compact multifunction IR calibrator

International Nuclear Information System (INIS)

Wyatt, C.L.; Jacobsen, L.; Steed, A.

1988-01-01

A compact portable multifunction calibrator designed for future sensor systems is described which enables a linearity calibration for all detectors simultaneously using a near small-area source, a high-resolution mapping of the focal plane with 10 microrad setability and with a blur of less than 100 microrad, system spectral response calibration (radiometer) using a Michelson interferometer source, relative spectral response (spectrometer) using high-temperature external commercial blackbody simulators, and an absolute calibration using an internal low-temperature extended-area source. 5 references

Monitoring and Mapping the Galactic Bulge (core Program)

Science.gov (United States)

Both neutron star and black hole binary transients are providing some of the most exciting RXTE science, and fortunately many are concentrated in the galactic bulge region. We propose to continue our twice weekly PCA scans of the region, which cover about 500 sq deg. The observations will be sensitive to new sources at the ~1 mCrab level (a factor of 10-60 more sensitive than the ASM in the region). We have had success finding new sources and new types of variability, including three millisecond pulsars, and new increased solid angle will improve the chances of finding more in the final RXTE years. We will continue efforts to search for variability in new and known sources. Companion follow-up proposals would be triggered by the results.

High-resolution observations of low-luminosity gigahertz-peaked spectrum and compact steep-spectrum sources

Science.gov (United States)

Collier, J. D.; Tingay, S. J.; Callingham, J. R.; Norris, R. P.; Filipović, M. D.; Galvin, T. J.; Huynh, M. T.; Intema, H. T.; Marvil, J.; O'Brien, A. N.; Roper, Q.; Sirothia, S.; Tothill, N. F. H.; Bell, M. E.; For, B.-Q.; Gaensler, B. M.; Hancock, P. J.; Hindson, L.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kapińska, A. D.; Lenc, E.; Morgan, J.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B.; Wu, C.; Zheng, Q.; Heywood, I.; Popping, A.

2018-06-01

We present very long baseline interferometry observations of a faint and low-luminosity (L1.4 GHz GPS) and compact steep-spectrum (CSS) sample. We select eight sources from deep radio observations that have radio spectra characteristic of a GPS or CSS source and an angular size of θ ≲ 2 arcsec, and detect six of them with the Australian Long Baseline Array. We determine their linear sizes, and model their radio spectra using synchrotron self-absorption (SSA) and free-free absorption (FFA) models. We derive statistical model ages, based on a fitted scaling relation, and spectral ages, based on the radio spectrum, which are generally consistent with the hypothesis that GPS and CSS sources are young and evolving. We resolve the morphology of one CSS source with a radio luminosity of 10^{25} W Hz^{-1}, and find what appear to be two hotspots spanning 1.7 kpc. We find that our sources follow the turnover-linear size relation, and that both homogeneous SSA and an inhomogeneous FFA model can account for the spectra with observable turnovers. All but one of the FFA models do not require a spectral break to account for the radio spectrum, while all but one of the alternative SSA and power-law models do require a spectral break to account for the radio spectrum. We conclude that our low-luminosity sample is similar to brighter samples in terms of their spectral shape, turnover frequencies, linear sizes, and ages, but cannot test for a difference in morphology.

Gravitational waves from double white dwarfs and AM CVn binaries

International Nuclear Information System (INIS)

Nelemans, Gijs

2003-01-01

I give a brief overview of our model for the galactic population of compact binaries that is used to predict the low-frequency gravitational wave signal from the galaxy, and discuss recent observational developments that will enable us to test and improve this model. The SPY project will discover some 150 new close double white dwarfs and, recently, two ROSAT sources turned out to be new AM CVn candidates, one with an orbital period of only 5 min. I give an update on the expected binaries that will be resolved by LISA and discuss what we can learn about the galactic population of compact binaries once LISA gives her first results

The Fermi Galactic Center GeV Excess and Implications for Dark Matter

Energy Technology Data Exchange (ETDEWEB)

Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States); Albert, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d’Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bissaldi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); Blandford, R. D.; Bloom, E. D.; Bottacini, E. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Bonino, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier (France); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Collaboration: (The Fermi LAT Collaboration); and others

2017-05-01

The region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what is expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the GeV excess using 6.5 yr of data from the Fermi Large Area Telescope. We characterize the uncertainty of the GC excess spectrum and morphology due to uncertainties in cosmic-ray source distributions and propagation, uncertainties in the distribution of interstellar gas in the Milky Way, and uncertainties due to a potential contribution from the Fermi bubbles. We also evaluate uncertainties in the excess properties due to resolved point sources of gamma rays. The GC is of particular interest, as it would be expected to have the brightest signal from annihilation of weakly interacting massive dark matter (DM) particles. However, control regions along the Galactic plane, where a DM signal is not expected, show excesses of similar amplitude relative to the local background. Based on the magnitude of the systematic uncertainties, we conservatively report upper limits for the annihilation cross-section as a function of particle mass and annihilation channel.

Visibility of Active Galactic Nuclei in the Illustris Simulation

Science.gov (United States)

Hutchinson-Smith, Tenley; Kelley, Luke; Moreno, Jorge; Hernquist, Lars; Illustris Collaboration

2018-01-01

Active galactic nuclei (AGN) are the very bright, luminous regions surrounding supermassive black holes (SMBH) located at the centers of galaxies. Supermassive black holes are the source of AGN feedback, which occurs once the SMBH reaches a certain critical mass. Almost all large galaxies contain a SMBH, but SMBH binaries are extremely rare. Finding these binary systems are important because it can be a source of gravitational waves if the two SMBH collide. In order to study supermassive black holes, astronomers will often rely on the AGN’s light in order to locate them, but this can be difficult due to the extinction of light caused by the dust and gas surrounding the AGN. My research project focuses on determining the fraction of light we can observe from galactic centers using the Illustris simulation, one of the most advanced cosmological simulations of the universe which was created using a hydrodynamic code and consists of a moving mesh. Measuring the fraction of light observable from galactic centers will help us know what fraction of the time we can observe dual and binary AGN in different galaxies, which would also imply a binary SMBH system. In order to find how much light is being blocked or scattered by the gas and dust surrounding the AGN, we calculated the density of the gas and dust along the lines of sight. I present results including the density of gas along different lines of sight and how it correlates with the image of the galaxy. Future steps include taking an average of the column densities for all the galaxies in Illustris and studying them as a function of galaxy type (before merger, during merger, and post-merger), which will give us information on how this can also affect the AGN luminosity.

Dark matter and pulsar model constraints from Galactic Center Fermi-LAT gamma-ray observations

Science.gov (United States)

Gordon, Chris; Macías, Oscar

2013-10-01

Employing Fermi-LAT gamma-ray observations, several independent groups have found excess extended gamma-ray emission at the Galactic Center (GC). Both annihilating dark matter (DM) or a population of ˜103 unresolved millisecond pulsars (MSPs) are regarded as well-motivated possible explanations. However, there are significant uncertainties in the diffuse galactic background at the GC. We have performed a revaluation of these two models for the extended gamma-ray source at the GC by accounting for the systematic uncertainties of the Galactic diffuse emission model. We also marginalize over point-source and diffuse background parameters in the region of interest. We show that the excess emission is significantly more extended than a point source. We find that the DM (or pulsar-population) signal is larger than the systematic errors and therefore proceed to determine the sectors of parameter space that provide an acceptable fit to the data. We find that a population of 1000-2000 MSPs with parameters consistent with the average spectral shape of Fermi-LAT measured MSPs is able to fit the GC excess emission. For DM, we find that a pure τ+τ- annihilation channel is not a good fit to the data. But a mixture of τ+τ- and bb¯ with a ⟨σv⟩ of order the thermal relic value and a DM mass of around 20 to 60 GeV provides an adequate fit.

Sagittarius A* as an origin of the Galactic PeV cosmic rays?

Energy Technology Data Exchange (ETDEWEB)

Fujita, Yutaka [Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Murase, Kohta; Kimura, Shigeo S., E-mail: fujita@vega.ess.sci.osaka-u.ac.jp, E-mail: murase@psu.edu, E-mail: szk323@psu.edu [Center for Particle and Gravitational Astrophysics, Department of Physics, Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

2017-04-01

Supernova remnants (SNRs) have commonly been considered as a source of the observed PeV cosmic rays (CRs) or a Galactic PeV particle accelerator ('Pevatron'). In this work, we study Sagittarius A* (Sgr A*), which is the low-luminosity active galactic nucleus of the Milky Way Galaxy, as another possible canditate of the Pevatron, because it sometimes became very active in the past. We assume that a large number of PeV CRs were injected by Sgr A* at the outburst about 10{sup 7} yr ago when the Fermi bubbles were created. We constrain the diffusion coefficient for the CRs in the Galactic halo on the condition that the CRs have arrived on the Earth by now, while a fairly large fraction of them have escaped from the halo. Based on a diffusion-halo model, we solve a diffusion equation for the CRs and compare the results with the CR spectrum on the Earth. The observed small anisotropy of the arrival directions of CRs may be explained if the diffusion coefficient in the Galactic disk is smaller than that in the halo. Our model predicts that a boron-to-carbon ratio should be energy-independent around the knee, where the CRs from Sgr A* become dominant. It is unlikely that the spectrum of the CRs accelerated at the outburst is represented by a power-law similar to the one for those responsible for the gamma-ray emission from the central molecular zone (CMZ) around the Galactic center.

Fossil imprint of a powerful flare at the galactic center along the Magellanic stream

Energy Technology Data Exchange (ETDEWEB)

Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006 (Australia); Maloney, Philip R. [CASA, University of Colorado, Boulder, CO 80309-0389 (United States); Sutherland, Ralph S. [Mount Stromlo Observatory, Australia National University, Woden, ACT 2611 (Australia); Madsen, G. J. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

2013-11-20

give rise to a polar angle dependence in the Hα emission. Thus it is plausible that the Stream Hα emission arose from a 'Seyfert flare' that was active 1-3 Myr ago, consistent with the cosmic ray lifetime in the Fermi bubbles. Sgr A{sup *} activity today is greatly suppressed (70-80 dB) relative to the Seyfert outburst. The rapid change over a huge dynamic range in ionizing luminosity argues for a compact UV source with an extremely efficient (presumably magneto-hydrodynamic) 'drip line' onto the accretion disk.

The radio properties of infrared-faint radio sources

Science.gov (United States)

Middelberg, E.; Norris, R. P.; Hales, C. A.; Seymour, N.; Johnston-Hollitt, M.; Huynh, M. T.; Lenc, E.; Mao, M. Y.

2011-02-01

Context. Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4 GHz, but that are invisible at 3.6 μm when using sensitive Spitzer observations with μJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. Aims: High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. Methods: We imaged a sample of 17 IFRS at 4.8 GHz and 8.6 GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. Results: We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spectral indices larger than -0.7. We also find that, given the IR non-detections, the ratio of 1.4 GHz flux density to 3.6 μm flux density is very high, and this puts them into the same regime as high-redshift radio galaxies. Conclusions: The evidence that IFRS are predominantly high-redshift sources driven by active galactic nuclei (AGN) is strong, even though not all IFRS may be caused by the same phenomenon. Compared to the rare and painstakingly collected high-redshift radio galaxies, IFRS appear to be much more abundant, but less luminous, AGN-driven galaxies at similar cosmological distances.

The Smith Cloud: surviving a high-speed transit of the Galactic disc

Science.gov (United States)

Tepper-García, Thor; Bland-Hawthorn, Joss

2018-02-01

The origin and survival of the Smith high-velocity H I cloud has so far defied explanation. This object has several remarkable properties: (i) its prograde orbit is ≈100 km s-1 faster than the underlying Galactic rotation; (ii) its total gas mass (≳ 4 × 106 M⊙) exceeds the mass of all other high-velocity clouds (HVCs) outside of the Magellanic Stream; (iii) its head-tail morphology extends to the Galactic H I disc, indicating some sort of interaction. The Smith Cloud's kinetic energy rules out models based on ejection from the disc. We construct a dynamically self-consistent, multi-phase model of the Galaxy with a view to exploring whether the Smith Cloud can be understood in terms of an infalling, compact HVC that has transited the Galactic disc. We show that while a dark-matter (DM) free HVC of sufficient mass and density can reach the disc, it does not survive the transit. The most important ingredient to survival during a transit is a confining DM subhalo around the cloud; radiative gas cooling and high spatial resolution (≲ 10pc) are also essential. In our model, the cloud develops a head-tail morphology within ∼10 Myr before and after its first disc crossing; after the event, the tail is left behind and accretes on to the disc within ∼400 Myr. In our interpretation, the Smith Cloud corresponds to a gas 'streamer' that detaches, falls back and fades after the DM subhalo, distorted by the disc passage, has moved on. We conclude that subhaloes with MDM ≲ 109 M⊙ have accreted ∼109 M⊙ of gas into the Galaxy over cosmic time - a small fraction of the total baryon budget.

Variations in the small-scale galactic magnetic field and short time-scale intensity variations of extragalactic radio sources

International Nuclear Information System (INIS)

Simonetti, J.H.

1985-01-01

Structure functions of the Faraday rotation measures (RMs) of extragalactic radio sources are used to investigate variations in the interstellar magnetic field on length scales of approx.0.01 to 100 pc. Model structure functions derived assuming a power-law power spectrum of irregularities in n/sub e/B, are compared with those observed. The results indicate an outer angular scale for RM variations of approximately less than or equal to 5 0 and evidence for RM variations on scales as small as 1'. Differences in the variance of n/sub e/B fluctuations for various lines of sight through the Galaxy are found. Comparison of pulsar scintillations in right- and left-circular polarizations yield an upper limit to the variations in n/sub e/ on a length scale of approx.10 11 cm. RMs were determined through high-velocity molecular flows in galactic star-formation regions, with the goal of constraining magnetic fields in and near the flows. RMs of 7 extragalactic sources with a approx.20 arcmin wide area seen through Cep A, fall in two groups separated by approx.150 rad m -2 - large given our knowledge of RM variations on small angular scales and possibly a result of the anisotropy of the high-velocity material

ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

Energy Technology Data Exchange (ETDEWEB)

McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Lockman, F. J. [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States); Dickey, J. M. [School of Physics and Mathematics, University of Tasmania, TAS 7001 (Australia); Gaensler, B. M.; Green, A. J., E-mail: naomi.mcclure-griffiths@csiro.au [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

2013-06-10

We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

International Nuclear Information System (INIS)

McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S.; Lockman, F. J.; Dickey, J. M.; Gaensler, B. M.; Green, A. J.

2013-01-01

We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of ∼14 km s –1 , and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at ∼200 km s –1 in a Galactic wind.

Compact portable electric power sources

Energy Technology Data Exchange (ETDEWEB)

Fry, D.N.; Holcomb, D.E.; Munro, J.K.; Oakes, L.C.; Matson, M.J.

1997-02-01

This report provides an overview of recent advances in portable electric power source (PEPS) technology and an assessment of emerging PEPS technologies that may meet US Special Operations Command`s (SOCOM) needs in the next 1--2- and 3--5-year time frames. The assessment was performed through a literature search and interviews with experts in various laboratories and companies. Nineteen PEPS technologies were reviewed and characterized as (1) PEPSs that meet SOCOM requirements; (2) PEPSs that could fulfill requirements for special field conditions and locations; (3) potentially high-payoff sources that require additional R and D; and (4) sources unlikely to meet present SOCOM requirements. 6 figs., 10 tabs.

Pressing device for producing compacts from source material in powder form in particular pulverized nuclear reactor fuel

International Nuclear Information System (INIS)

Heller, G.; Adelmann, M.; Konigs, W.; Wendorf, W.

1984-01-01

Pressing device for producing compacts from source material in powder form, in particular pulverized nuclear reactor fuel having a die-plate contained in platen and a bore associated with a ram, for receiving source material powder, a filling shoe, and a reservoir for powder connected by a hose to the filling shoe. The device is characterized by a passing wheel in the filling shoe as filling aid means; a tube containing a feedscrew disposed between the reservoir and hose as metering means; the reservoir having a bottom part with a can type place-on part with an opening eccentric to the axis; a coupling part and a cover part are placed on the open part of the can, these parts are also provided with a passageway to the feedscrew eccentric to the longitudinal axis

Gamma-ray and X-ray emission from the Galactic centre: hints on the nuclear star cluster formation history

Science.gov (United States)

Arca-Sedda, Manuel; Kocsis, Bence; Brandt, Timothy D.

2018-06-01

The Milky Way centre exhibits an intense flux in the gamma and X-ray bands, whose origin is partly ascribed to the possible presence of a large population of millisecond pulsars (MSPs) and cataclysmic variables (CVs), respectively. However, the number of sources required to generate such an excess is much larger than what is expected from in situ star formation and evolution, opening a series of questions about the formation history of the Galactic nucleus. In this paper we make use of direct N-body simulations to investigate whether these sources could have been brought to the Galactic centre by a population of star clusters that underwent orbital decay and formed the Galactic nuclear star cluster (NSC). Our results suggest that the gamma ray emission is compatible with a population of MSPs that were mass segregated in their parent clusters, while the X-ray emission is consistent with a population of CVs born via dynamical interactions in dense star clusters. Combining observations with our modelling, we explore how the observed γ ray flux can be related to different NSC formation scenarios. Finally, we show that the high-energy emission coming from the galactic central regions can be used to detect black holes heavier than 105M⊙ in nearby dwarf galaxies.

Development and studies on a compact electron cyclotron resonance plasma source

Science.gov (United States)

Ganguli, A.; Tarey, R. D.; Arora, N.; Narayanan, R.

2016-04-01

It is well known that electron cyclotron resonance (ECR) produced plasmas are efficient, high-density plasma sources and have many industrial applications. The concept of a portable compact ECR plasma source (CEPS) would thus become important from an application point of view. This paper gives details of such a CEPS that is both portable and easily mountable on a chamber of any size. It uses a fully integrated microwave line operating at 2.45 GHz, up to 800 W, cw. The required magnetic field is produced by a set of suitably designed NdFeB ring magnets; the device has an overall length of  ≈60 cm and weighs  ≈14 kg including the permanent magnets. The CEPS was attached to a small experimental chamber to judge its efficacy for plasma production. In the pressure range of 0.5-10 mTorr and microwave power of  ≈400-500 W the experiments indicate that the CEPS is capable of producing high-density plasma (≈9  ×  1011-1012 cm-3) with bulk electron temperature in the range  ≈2-3 eV. In addition, a warm electron population with density and temperature in the range ≈7  ×  108-109 cm-3 and  ≈45-80 eV, respectively has been detected. This warm population plays an important role at high pressures in maintaining the high-density plasma, when plasma flow from the CEPS into the test chamber is strongly affected.

The design of 28 GHz ECR Ion Source for the Compact Linear Accelerator in Korea

International Nuclear Information System (INIS)

MiSook, Won; ByoungSeob, Lee; JinYong, Park; DongJun Park; JongPil, Kim; JongSeong, Bae; JungKeum, Ahn; SonJong, Wang; Nakagawa, T.

2012-01-01

The construction of a compact linear accelerator is in progress by Korea Basic Science Institute. The main capability of this facility is the production of multiply ionized metal clusters and the generation more intense beams of highly charged ions for material, medical and nuclear physical research. To produce the intense beam of highly charged ions, we will construct an Electron Cyclotron Resonance Ion Source (ECRIS) using 28 GHz microwaves. For this ECRIS, the design of a superconducting magnet, microwave inlet, beam extraction and plasma chamber was completed. Also we are constructing a superconducting magnet system. In this poster, we will report the current status of development of our 28 GHz ECRIS. (authors)

INFERRING THE GALACTIC POTENTIAL WITH GAIA AND FRIENDS: SYNERGIES WITH OTHER SURVEYS

Energy Technology Data Exchange (ETDEWEB)

Sanderson, Robyn E., E-mail: robyn@astro.columbia.edu [Department of Astronomy, Columbia University, New York, NY 10027 (United States)

2016-02-10

In the coming decade, the Gaia satellite will precisely measure the positions and velocities of millions of stars in the Galactic halo, including stars in many tidal streams. These streams, the products of hierarchical accretion of satellite galaxies by the Milky Way (MW), can be used to infer the Galactic gravitational potential thanks to their initial compactness in phase space. Plans for observations to extend Gaia’s radial velocity (RV) measurements to faint stars, and to determine precise distances to RR Lyrae in streams, would further extend the power of Gaia’s kinematic catalog to characterize the MW’s potential at large Galactocentric distances. In this work I explore the impact of these extra data on the ability to fit the potential using the method of action clustering, which statistically maximizes the information content (clumpiness) of the action space of tidal streams, eliminating the need to determine stream membership for individual stars. Using a mock halo in a toy spherical potential, updated post-launch error models for Gaia, and estimates for RV and distance errors for the tracers to be followed up, I show that combining either form of additional information with the Gaia catalog greatly reduces the bias in determining the scale radius and total mass of the Galaxy compared to the use of Gaia data alone.

Compact laser-diode-based femtosecond sources

International Nuclear Information System (INIS)

Brown, C T A; Cataluna, M A; Lagatsky, A A; Rafailov, E U; Agate, M B; Leburn, C G; Sibbett, W

2004-01-01

This paper describes the development of compact femtosecond laser systems that are capable of being directly pumped by laser diodes or are based directly on laser diodes. The paper demonstrates the latest results in a highly efficient vibronic based gain medium and a diode-pumped Yb:KYW laser is reported that has a wall plug efficiency >14%. A Cr 4+ :YAG oscillator is described that generates transform-limited pulses of 81 fs duration at a pulse repetition frequency of >4 GHz. The development of Cr 3+ :LiSAF lasers that can be operated using power supplies based on batteries is briefly discussed. We also present a summary of work being carried out on the generation of fs-pulses from laser diodes and discuss the important issues in this area. Finally, we outline results obtained on the generation of pulses as short as 550 fs directly from a two-section quantum dot laser without any external pulse compression

The galactic distribution of pulsars

International Nuclear Information System (INIS)

Lyne, A.G.

1982-01-01

The galactic distribution of pulsars follows the general form of many population I objects in galactocentric radius, but has a wide distribution above and below the plane due to high space velocities imparted to the pulsars at birth. Statistical studies of the properties of large numbers of pulsars and proper motion measurements demonstrate that the effective magnetic dipole moments decay on a timescale of about 8 million years. This work provides a better knowledge of pulsar evolution and ages and shows that a birthrate of one pulsar every 20 to 50 years is required to sustain the observed galactic population of 300,000. This rate is comparable with most recent estimates of the galactic supernova rate, but requires nearly all supernovae to produce active pulsars. (orig.)

Strong Support for the Millisecond Pulsar Origin of the Galactic Center GeV Excess.

Science.gov (United States)

Bartels, Richard; Krishnamurthy, Suraj; Weniger, Christoph

2016-02-05

Using γ-ray data from the Fermi Large Area Telescope, various groups have identified a clear excess emission in the Inner Galaxy, at energies around a few GeV. This excess resembles remarkably well a signal from dark-matter annihilation. One of the most compelling astrophysical interpretations is that the excess is caused by the combined effect of a previously undetected population of dim γ-ray sources. Because of their spectral similarity, the best candidates are millisecond pulsars. Here, we search for this hypothetical source population, using a novel approach based on wavelet decomposition of the γ-ray sky and the statistics of Gaussian random fields. Using almost seven years of Fermi-LAT data, we detect a clustering of photons as predicted for the hypothetical population of millisecond pulsar, with a statistical significance of 10.0σ. For plausible values of the luminosity function, this population explains 100% of the observed excess emission. We argue that other extragalactic or Galactic sources, a mismodeling of Galactic diffuse emission, or the thick-disk population of pulsars are unlikely to account for this observation.

Possible galactic origin of. gamma. -ray bursts

Energy Technology Data Exchange (ETDEWEB)

Manchanda, R K; Ramsden, D [Southampton Univ. (UK). Dept. of Physics

1977-03-31

It is stated that extragalactic models for the origin of non-solar ..gamma..-ray bursts include supernova bursts in remote galaxies, and the collapse of the cores of active stars, whilst galactic models are based on flare stars, thermonuclear explosions in neutron stars and the sudden accretion of cometary gas on to neutron stars. The acceptability of any of these models may be tested by the observed size spectrum of the ..gamma..-ray bursts. The extragalactic models predict a power law spectrum with number index -1.5, whilst for the galactic models the number index will be -1. Experimental data on ..gamma..-ray bursts is, however, still meagre, and so far only 44 confirmed events have been recorded by satellite-borne instruments. The number spectrum of the observed ..gamma..-ray bursts indicates that the observed distribution for events with an energy < 10/sup -4/ erg/cm/sup 2/ is flat; this makes the choice of any model completely arbitrary. An analysis of the observed ..gamma..-ray events is here presented that suggests very interesting possibilities for their origin. There appears to be a preferred mean energy for ..gamma..-ray bursts; some 90% of the recorded events show a mean energy between 5 x 10/sup -5/ and 5 x 10/sup -4/ erg/cm/sup 2/, contrary to the predicted characteristics of the number spectrum of various models. A remarkable similarity is found between the distribution of ..gamma..-ray bursts and that of supernova remnants, suggesting a genetic relationship between the two and the galactic origin of the ..gamma..-ray bursts, and the burst source could be identified with completely run down neutron stars, formed during supernova explosions.

Compact electron storage rings

International Nuclear Information System (INIS)

Williams, G.P.

1987-01-01

There have been many recent developments in the area of compact storage rings. Such rings would have critical wavelengths of typically 10 A, achieved with beam energies of several hundreds of MeV and superconducting dipole fields of around 5 Tesla. Although the primary motivation for progress in this area is that of commercial x-ray lithography, such sources might be an attractive source for college campuses to operate. They would be useful for many programs in materials science, solid state, x-ray microscopy and other biological areas. We discuss the properties of such sources and review developments around the world, primarily in the USA, japan and W. Germany

Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

Energy Technology Data Exchange (ETDEWEB)

Callingham, J. R.; Gaensler, B. M.; Sadler, E. M.; Lenc, E. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Ekers, R. D.; Bell, M. E. [CSIRO Astronomy and Space Science (CASS), Marsfield, NSW 2122 (Australia); Line, J. L. B.; Hancock, P. J.; Kapińska, A. D.; McKinley, B.; Procopio, P. [ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO) (Australia); Hurley-Walker, N.; Tingay, S. J.; Franzen, T. M. O.; Morgan, J. [International Centre for Radio Astronomy Research (ICRAR), Curtin University, Bentley, WA 6102 (Australia); Dwarakanath, K. S. [Raman Research Institute (RRI), Bangalore 560080 (India); For, B.-Q. [International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia, Crawley, WA 6009 (Australia); Hindson, L.; Johnston-Hollitt, M. [School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140 (New Zealand); Offringa, A. R., E-mail: joseph.callingham@sydney.edu.au [Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo (Netherlands); and others

2017-02-20

We present a sample of 1483 sources that display spectral peaks between 72 MHz and 1.4 GHz, selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The GLEAM survey is the widest fractional bandwidth all-sky survey to date, ideal for identifying peaked-spectrum sources at low radio frequencies. Our peaked-spectrum sources are the low-frequency analogs of gigahertz-peaked spectrum (GPS) and compact-steep spectrum (CSS) sources, which have been hypothesized to be the precursors to massive radio galaxies. Our sample more than doubles the number of known peaked-spectrum candidates, and 95% of our sample have a newly characterized spectral peak. We highlight that some GPS sources peaking above 5 GHz have had multiple epochs of nuclear activity, and we demonstrate the possibility of identifying high-redshift ( z > 2) galaxies via steep optically thin spectral indices and low observed peak frequencies. The distribution of the optically thick spectral indices of our sample is consistent with past GPS/CSS samples but with a large dispersion, suggesting that the spectral peak is a product of an inhomogeneous environment that is individualistic. We find no dependence of observed peak frequency with redshift, consistent with the peaked-spectrum sample comprising both local CSS sources and high-redshift GPS sources. The 5 GHz luminosity distribution lacks the brightest GPS and CSS sources of previous samples, implying that a convolution of source evolution and redshift influences the type of peaked-spectrum sources identified below 1 GHz. Finally, we discuss sources with optically thick spectral indices that exceed the synchrotron self-absorption limit.

An Integrated Picture of Star Formation, Metallicity Evolution, and Galactic Stellar Mass Assembly

Science.gov (United States)

Cowie, L. L.; Barger, A. J.

2008-10-01

We present an integrated study of star formation and galactic stellar mass assembly from z = 0.05 to 1.5 and galactic metallicity evolution from z = 0.05 to 0.9 using a very large and highly spectroscopically complete sample selected by rest-frame NIR bolometric flux in the GOODS-N. We assume a Salpeter IMF and fit Bruzual & Charlot models to compute the galactic stellar masses and extinctions. We determine the expected formed stellar mass density growth rates produced by star formation and compare them with the growth rates measured from the formed stellar mass functions by mass interval. We show that the growth rates match if the IMF is slightly increased from the Salpeter IMF at intermediate masses (~10 M⊙). We investigate the evolution of galaxy color, spectral type, and morphology with mass and redshift and the evolution of mass with environment. We find that applying extinction corrections is critical when analyzing galaxy colors; e.g., nearly all of the galaxies in the green valley are 24 μm sources, but after correcting for extinction, the bulk of the 24 μm sources lie in the blue cloud. We find an evolution of the metallicity-mass relation corresponding to a decrease of 0.21 +/- 0.03 dex between the local value and the value at z = 0.77 in the 1010-1011 M⊙ range. We use the metallicity evolution to estimate the gas mass of the galaxies, which we compare with the galactic stellar mass assembly and star formation histories. Overall, our measurements are consistent with a galaxy evolution process dominated by episodic bursts of star formation and where star formation in the most massive galaxies (gtrsim1011 M⊙) ceases at z Technology, the University of California, and NASA and was made possible by the generous financial support of the W. M. Keck Foundation.

Comparison of Model Prediction With Measurements of Galactic Background Noise at L-Band

DEFF Research Database (Denmark)

Le Vine, David M.; Abraham, Saji; Kerr, Yann H.

2005-01-01

The spectral window at L-band (1.413 GHz) is important for passive remote sensing of surface parameters such as soil moisture and sea surface salinity that are needed to understand the hydrological cycle and ocean circulation. Radiation from celestial sources (mostly galactic) is strong in this w...

Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope

Energy Technology Data Exchange (ETDEWEB)

Hooper, Dan; /Fermilab /Chicago U., Astron. Astrophys. Ctr.; Goodenough, Lisa; /New York U.

2010-10-01

We analyze the first two years of data from the Fermi Gamma Ray Space Telescope from the direction of the inner 10{sup o} around the Galactic Center with the intention of constraining, or finding evidence of, annihilating dark matter. We find that the morphology and spectrum of the emission between 1.25{sup o} and 10{sup o} from the Galactic Center is well described by a the processes of decaying pions produced in cosmic ray collisions with gas, and the inverse Compton scattering of cosmic ray electrons in both the disk and bulge of the Inner Galaxy, along with gamma rays from known points sources in the region. The observed spectrum and morphology of the emission within approximately 1.25{sup o} ({approx}175 parsecs) of the Galactic Center, in contrast, cannot be accounted for by these processes or known sources. We find that an additional component of gamma ray emission is clearly present which is highly concentrated around the Galactic Center, but is not point-like in nature. The observed morphology of this component is consistent with that predicted from annihilating dark matter with a cusped (and possibly adiabatically contracted) halo distribution ({rho} {proportional_to} r{sup -1.34{+-}0.04}). The observed spectrum of this component, which peaks at energies between 2-4 GeV (in E{sup 2} units), is well fit by that predicted for a 7.3-9.2 GeV dark matter particle annihilating primarily to tau leptons with a cross section in the range of <{sigma}{nu}> = 3.3 x 10{sup -27} to 1.5 x 10{sup -26} cm{sup 3}/s, depending on how the dark matter distribution is normalized. We discuss other possible sources for this component, but argue that they are unlikely to account for the observed emission.

A Compact Group of Galaxies at z = 2.48 Hosting an AGN-driven Outflow

Science.gov (United States)

Shih, Hsin-Yi; Stockton, Alan

2015-12-01

We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 1011M⊙ and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass-metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The work is also based, in part, on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Compact XFEL and AMO sciences: SACLA and SCSS

International Nuclear Information System (INIS)

Yabashi, M; Tanaka, H; Tanaka, T; Tomizawa, H; Nagasono, M; Ishikawa, T; Harries, J R; Hikosaka, Y; Hishikawa, A; Nagaya, K; Saito, N; Shigemasa, E; Yamanouchi, K; Ueda, K; Togashi, T

2013-01-01

The concept, design and performance of Japan's compact free-electron laser (FEL) facilities, the SPring-8 Compact SASE Source test accelerator (SCSS) and SPring-8 Angstrom Compact free electron LAser (SACLA), and their applications in mainly atomic, molecular and optical science are reviewed. At SCSS, intense, ultrafast FEL pulses at extreme ultraviolet (EUV) wavelengths have been utilized for investigating various multi-photon processes in atoms, molecules and clusters by means of ion and electron spectroscopy. The quantum optical effect superfluorescence has been observed with EUV excitation. A pump–probe technique combining FEL pulses with near infrared laser pulses has been realized to study the ultrafast dynamics of atoms, molecules and clusters in the sub-picosecond regime. At SACLA, deep inner-shell multi-photon ionization by intense x-ray FEL pulses has been investigated. The development of seeded FEL sources for producing transversely and temporally coherent light, as well as the expected impact on advanced science are discussed. (invited paper)

Comment on "Characterizing the population of pulsars in the Galactic bulge with the Fermi large area telescope" [arXiv:1705.00009v1

Science.gov (United States)

Bartels, Richard; Hooper, Dan; Linden, Tim; Mishra-Sharma, Siddharth; Rodd, Nicholas L.; Safdi, Benjamin R.; Slatyer, Tracy R.

2018-06-01

The Fermi-LAT Collaboration recently presented a new catalog of gamma-ray sources located within the 40 ° × 40 ° region around the Galactic Center Ajello et al. (2017) - the Second Fermi Inner Galaxy (2FIG) catalog. Utilizing this catalog, they analyzed models for the spatial distribution and luminosity function of sources with a pulsar-like gamma-ray spectrum. Ajello et al. (2017) v1 also claimed to detect, in addition to a disk-like population of pulsar-like sources, an approximately 7 σ preference for an additional centrally concentrated population of pulsar-like sources, which they referred to as a "Galactic Bulge" population. Such a population would be of great interest, as it would support a pulsar interpretation of the gamma-ray excess that has long been observed in this region. In an effort to further explore the implications of this new source catalog, we attempted to reproduce the results presented by the Fermi-LAT Collaboration, but failed to do so. Mimicking as closely as possible the analysis techniques undertaken in Ajello et al. (2017), we instead find that our likelihood analysis favors a very different spatial distribution and luminosity function for these sources. Most notably, our results do not exhibit a strong preference for a "Galactic Bulge" population of pulsars. Furthermore, we find that masking the regions immediately surrounding each of the 2FIG pulsar candidates does not significantly impact the spectrum or intensity of the Galactic Center gamma-ray excess. Although these results refute the claim of strong evidence for a centrally concentrated pulsar population presented in Ajello et al. (2017), they neither rule out nor provide support for the possibility that the Galactic Center excess is generated by a population of low-luminosity and currently largely unobserved pulsars. In a spirit of maximal openness and transparency, we have made our analysis code available at https://github.com/bsafdi/GCE-2FIG.

G25.5 + 0.2: a very young supernova remnant or a galactic planetary nebula?

International Nuclear Information System (INIS)

White, R.L.; Becker, R.H.

1990-01-01

G25.5 + 0.2, a radio source suggested by previous authors to be a very young galactic supernova remnant, is more likely to be a planetary nebula. Its IRAS colours and fluxes and its radio spectrum and morphology are all consistent with the properties of planetary nebulae; its radio flux and distance imply a large mass of ionized gas, which is expected from a Type I planetary nebula lying in the galactic plane. We suggest some definitive observations which should be able to determine whether this interesting object is a planetary nebula or a supernova remnant. (author)

Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust

DEFF Research Database (Denmark)

Cardoso, J. F.; Delabrouille, J.; Ganga, K.

2015-01-01

measurements toward extragalactic sources. These components bear resemblance along the Galactic plane and in some regions such as the Fan and North Polar Spur regions. The poor match observed in other regions shows, however, that dust, cosmic-ray electrons, and thermal electrons generally sample different...

Limb darkening of a K giant in the galactic bulge : Planet photometry of MACHO 97-BLG-28

NARCIS (Netherlands)

Albrow, MD; Beaulieu, JP; Caldwell, JAR; Dominik, M; Greenhill, J; Hill, K; Kane, S; Martin, R; Menzies, J; Pel, JW; Pollard, K; Sackett, PD; Sahu, KC; Vermaak, P; Watson, R; Williams, A; Sahu, MS

1999-01-01

We present the PLANET photometric data set(10) for the binary-lens microlensing event MACHO 97-BLG-28, consisting of 696 I- and V-band measurements, and analyze it to determine the radial surface brightness profile of the Galactic bulge source star. The microlensed source, demonstrated to be a K

Compact sub-nanosecond pulse seed source with diode laser driven by a high-speed circuit

Science.gov (United States)

Wang, Xiaoqian; Wang, Bo; Wang, Junhua; Cheng, Wenyong

2018-06-01

A compact sub-nanosecond pulse seed source with 1550 nm diode laser (DL) was obtained by employing a high-speed circuit. The circuit mainly consisted of a short pulse generator and a short pulse driver. The short pulse generator, making up of a complex programmable logic device (CPLD), a level translator, two programmable delay chips and an AND gate chip, output a triggering signal to control metal-oxide-semiconductor field-effect transistor (MOSFET) switch of the short pulse driver. The MOSFET switch with fast rising time and falling time both shorter than 1 ns drove the DL to emit short optical pulses. Performances of the pulse seed source were tested. The results showed that continuously adjustable repetition frequency ranging from 500 kHz to 100 MHz and pulse duration in the range of 538 ps to 10 ns were obtained, respectively. 537 μW output was obtained at the highest repetition frequency of 100 MHz with the shortest pulse duration of 538 ps. These seed pulses were injected into an fiber amplifier, and no optical pulse distortions were found.

Interpretation of astrophysical neutrinos observed by IceCube experiment by setting Galactic and extra-Galactic spectral components

CERN Document Server

Marinelli, Antonio; Grasso, Dario; Urbano, Alfredo; Valli, Mauro

2016-01-01

The last IceCube catalog of High Energy Starting Events (HESE) obtained with a livetime of 1347 days comprises 54 neutrino events equally-distributed between the three families with energies between 25 TeV and few PeVs. Considering the homogeneous flavors distribution (1:1:1) and the spectral features of these neutrinos the IceCube collaboration claims the astrophysical origin of these events with more than $5\\sigma$. The spatial distribution of cited events does not show a clear correlation with known astrophysical accelerators leaving opened both the Galactic and the extra-Galactic origin interpretations. Here, we compute the neutrino diffuse emission of our Galaxy on the basis of a recently proposed phenomenological model characterized by radially-dependent cosmic-ray (CR) transport properties. We show that the astrophysical spectrum measured by IceCube experiment can be well explained adding to the diffuse Galactic neutrino flux (obtained with this new model) a extra-Galactic component derived from the as...

THE BOLOCAM GALACTIC PLANE SURVEY. XI. TEMPERATURES AND SUBSTRUCTURE OF GALACTIC CLUMPS BASED ON 350 μM OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Merello, Manuel; Evans II, Neal J. [The University of Texas at Austin, Department of Astronomy, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States); Shirley, Yancy L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Rosolowsky, Erik [Department of Physics, 4-181 CCIS, University of Alberta, Edmonton, AB T6G 2E1 (Canada); Ginsburg, Adam [European Southern Observatory, ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-95748 Garching bei Munchen (Germany); Bally, John [CASA, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Battersby, Cara; Dunham, Michael M., E-mail: manuel@astro.as.utexas.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138 (United States)

2015-05-15

We present 107 maps of continuum emission at 350 μm from Galactic molecular clumps. Observed sources were mainly selected from the Bolocam Galactic Plane Survey (BGPS) catalog, with three additional maps covering star-forming regions in the outer Galaxy. The higher resolution of the SHARC-II images (8.″5 beam) compared with the 1.1 mm images from BGPS (33″ beam) allowed us to identify a large population of smaller substructures within the clumps. A catalog is presented for the 1386 sources extracted from the 350 μm maps. The color temperature distribution of clumps based on the two wavelengths has a median of 13.3 K and mean of 16.3 ± 0.4 K, assuming an opacity law index of 1.7. For the structures with good determination of color temperatures, the mean ratio of gas temperature, determined from NH{sub 3} observations, to dust color temperature is 0.88 and the median ratio is 0.76. About half the clumps have more than 2 substructures and 22 clumps have more than 10. The fraction of the mass in dense substructures seen at 350 μm compared to the mass of their parental clump is ∼0.19, and the surface densities of these substructures are, on average, 2.2 times those seen in the clumps identified at 1.1 mm. For a well-characterized sample, 88 structures (31%) exceed a surface density of 0.2 g cm{sup −2}, and 18 (6%) exceed 1.0 g cm{sup −2}, thresholds for massive star formation suggested by theorists.

A COMPARISON OF FAR-IR AND H I AS REDDENING PREDICTORS AT HIGH GALACTIC LATITUDE

International Nuclear Information System (INIS)

Peek, J. E. G.

2013-01-01

Both the Galactic 21 cm line flux from neutral hydrogen (H I) in interstellar medium and the far-infrared (FIR) emission from Galactic dust grains have been used to estimate the strength of Galactic reddening of distant sources. In this work we use a collection of uniform color distant galaxies as color standards to determine whether the H I method or the FIR method is superior. We find that the two methods both produce reasonably accurate maps, but that both show significant errors as compared to the typical color of the background galaxies. We find that a mixture of the FIR and H I maps in roughly a 2-to-1 ratio is clearly superior to either map alone. We recommend that future reddening maps should use both sets of data, and that well-constructed FIR and H I maps should both be vigorously pursued.

OGLE-III MICROLENSING EVENTS AND THE STRUCTURE OF THE GALACTIC BULGE

Energy Technology Data Exchange (ETDEWEB)

Wyrzykowski, Łukasz; Rynkiewicz, Alicja E.; Skowron, Jan; Kozłowski, Szymon; Udalski, Andrzej; Szymański, Michał K.; Kubiak, Marcin; Soszyński, Igor; Pietrzyński, Grzegorz; Poleski, Radosław; Pietrukowicz, Paweł; Pawlak, Michał, E-mail: lw@astrouw.edu.pl [Warsaw University Astronomical Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)

2015-01-01

We present and study the largest and most comprehensive catalog of microlensing events ever constructed. The sample of standard microlensing events comprises 3718 unique events from 2001-2009 with 1409 events that had not been detected before in real-time by the Early Warning System of the Optical Gravitational Lensing Experiment. The search pipeline uses machine learning algorithms to help find rare phenomena among 150 million objects and to derive the detection efficiency. Applications of the catalog can be numerous, from analyzing individual events to large statistical studies of the Galactic mass, kinematics distributions, and planetary abundances. We derive maps of the mean Einstein ring crossing time of events spanning 31 deg{sup 2} toward the Galactic center and compare the observed distributions with the most recent models. We find good agreement within the observed region and we see the signature of the tilt of the bar in the microlensing data. However, the asymmetry of the mean timescales seems to rise more steeply than predicted, indicating either a somewhat different orientation of the bar or a larger bar width. The map of events with sources in the Galactic bulge shows a dependence of the mean timescale on the Galactic latitude, signaling an increasing contribution from disk lenses closer to the plane relative to the height of the disk. Our data present a perfect set for comparing and enhancing new models of the central parts of the Milky Way and creating a three-dimensional picture of the Galaxy.

The galactic distribution of Wolf-Rayet stars

International Nuclear Information System (INIS)

Hidayat, B.; Supelli, K.; Hucht, K.A. van der

1982-01-01

On the basis of the most recent compilation of narrow-band photometry and absolute visual magnitudes of Wolf-Rayet stars, and adopting a normal interstellar extinction law in all directions, the galactic distribution of 132 of the 159 known galactic WR stars is presented and discussed. The spiral structure is found to be more clearly pronounced than in earlier studies. Furthermore the authors find an indication of two spiral arms at r=4 and 6 kpc. There appears to be an asymmetry of the z-distribution of single stars with respect to galactic longitude. The location of the WC8.5 and WC9 stars between 4.5 and 9 kpc from the galactic center is discussed in the context of Maeder's red supergiant to WR star scenario. (Auth.)

Spitzer Digs Up Galactic Fossil

Science.gov (United States)

2004-01-01

[figure removed for brevity, see original site] Figure 1 [figure removed for brevity, see original site] Figure 2 This false-color image taken by NASA's Spitzer Space Telescope shows a globular cluster previously hidden in the dusty plane of our Milky Way galaxy. Globular clusters are compact bundles of old stars that date back to the birth of our galaxy, 13 or so billion years ago. Astronomers use these galactic 'fossils' as tools for studying the age and formation of the Milky Way. Most clusters orbit around the center of the galaxy well above its dust-enshrouded disc, or plane, while making brief, repeated passes through the plane that each last about a million years. Spitzer, with infrared eyes that can see into the dusty galactic plane, first spotted the newfound cluster during its current pass. A visible-light image (inset of Figure 1) shows only a dark patch of sky. The red streak behind the core of the cluster is a dust cloud, which may indicate the cluster's interaction with the Milky Way. Alternatively, this cloud may lie coincidentally along Spitzer's line of sight. Follow-up observations with the University of Wyoming Infrared Observatory helped set the distance of the new cluster at about 9,000 light-years from Earth - closer than most clusters - and set the mass at the equivalent of 300,000 Suns. The cluster's apparent size, as viewed from Earth, is comparable to a grain of rice held at arm's length. It is located in the constellation Aquila. Astronomers believe that this cluster may be one of the last in our galaxy to be uncovered. This image composite was taken on April 21, 2004, by Spitzer's infrared array camera. It is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red). Galactic Fossil Found Behind Curtain of Dust In Figure 2, the image mosaic shows the same patch of sky in various wavelengths of light. While the visible-light image (left) shows a dark sky speckled

Galactic Winds and the Role Played by Massive Stars

Science.gov (United States)

Heckman, Timothy M.; Thompson, Todd A.

Galactic winds from star-forming galaxies play at key role in the evolution of galaxies and the intergalactic medium. They transport metals out of galaxies, chemically enriching the intergalactic medium and modifying the chemical evolution of galaxies. They affect the surrounding interstellar and circumgalactic media, thereby influencing the growth of galaxies though gas accretion and star formation. In this contribution we first summarize the physical mechanisms by which the momentum and energy output from a population of massive stars and associated supernovae can drive galactic winds. We use the prototypical example of M 82 to illustrate the multiphase nature of galactic winds. We then describe how the basic properties of galactic winds are derived from the data, and summarize how the properties of galactic winds vary systematically with the properties of the galaxies that launch them. We conclude with a brief discussion of the broad implications of galactic winds.

Study and modeling of the most energetic Active Galactic Nuclei with the Fermi satellite; Etude et modelisation des noyaux actifs de galaxie les plus energetiques avec le satellite Fermi

Energy Technology Data Exchange (ETDEWEB)

Sanchez, D.

2010-06-15

The Fermi satellite was launched in June 2008. The onboard LAT detector is dedicated to the study of galactic and extra-galactic gamma sources with an energy comprised between 200 MeV and 300 GeV. 1451 sources have been detected in less than 11 months. This document is divided into 6 chapters: 1) gamma astronomy, 2) the Fermi satellite, 3) the active galactic nuclei (NAG), 4) the observation of several blazars (PKS-2155-304 and PG-1553+113) and its simulation, 5) the observation of PKS-2155-304 with both RXTE and Fermi, and 6) conclusion

Proper Motions and Structural Parameters of the Galactic Globular Cluster M71

Energy Technology Data Exchange (ETDEWEB)

Cadelano, M.; Dalessandro, E.; Ferraro, F. R.; Miocchi, P.; Lanzoni, B.; Pallanca, C. [Dipartimento di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Massari, D. [INAF—Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)

2017-02-20

By exploiting two ACS/ HST data sets separated by a temporal baseline of ∼7 years, we have determined the relative stellar proper motions (PMs; providing membership) and the absolute PM of the Galactic globular cluster M71. The absolute PM has been used to reconstruct the cluster orbit within a Galactic, three-component, axisymmetric potential. M71 turns out to be in a low-latitude disk-like orbit inside the Galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. Since large differential reddening is known to affect this system, we took advantage of near-infrared, ground-based observations to re-determine the cluster center and density profile from direct star counts. The new structural parameters turn out to be significantly different from the ones quoted in the literature. In particular, M71 has a core and a half-mass radii almost 50% larger than previously thought. Finally, we estimate that the initial mass of M71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of X-ray sources.

The first fermi-lat catalog of sources above 10 GeV

Energy Technology Data Exchange (ETDEWEB)

Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Bernieri, E.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D' Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Franckowiak, A.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hewitt, J.; Hill, A. B.; Horan, D.; Hughes, R. E.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Massaro, E.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Orienti, M.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Saz Parkinson, P. M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stawarz, Łukasz; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.

2013-11-14

We present a catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first three years of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of >10GeV sources (1FHL) has 514 sources. For each source we present location, spectrum, a measure of variability, and associations with cataloged sources at other wavelengths. We found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, we find 20 (12) to have significant pulsations in the range >10GeV (>25GeV). In this work we also report that, at energies above 10 GeV, unresolved sources account for 27+/-8 % of the isotropic gamma-ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. We also highlight the subset of the 1FHL sources that are best candidates for detection at energies above 50-100 GeV with current and future ground-based gamma-ray observatories.

MODIFIED GRAVITY SPINS UP GALACTIC HALOS

Energy Technology Data Exchange (ETDEWEB)

Lee, Jounghun [Astronomy Program, Department of Physics and Astronomy, FPRD, Seoul National University, Seoul 151-747 (Korea, Republic of); Zhao, Gong-Bo [National Astronomy Observatories, Chinese Academy of Science, Beijing 100012 (China); Li, Baojiu [Institute of Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Koyama, Kazuya, E-mail: jounghun@astro.snu.ac.kr [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)

2013-01-20

We investigate the effect of modified gravity on the specific angular momentum of galactic halos by analyzing the halo catalogs at z = 0 from high-resolution N-body simulations for a f(R) gravity model that meets the solar-system constraint. It is shown that the galactic halos in the f(R) gravity model tend to acquire significantly higher specific angular momentum than those in the standard {Lambda}CDM model. The largest difference in the specific angular momentum distribution between these two models occurs for the case of isolated galactic halos with mass less than 10{sup 11} h {sup -1} M {sub Sun }, which are likely least shielded by the chameleon screening mechanism. As the specific angular momentum of galactic halos is rather insensitive to other cosmological parameters, it can in principle be an independent discriminator of modified gravity. We speculate a possibility of using the relative abundance of low surface brightness galaxies (LSBGs) as a test of general relativity given that the formation of the LSBGs occurs in fast spinning dark halos.

A simple scheme for injection and extraction in compact rings

International Nuclear Information System (INIS)

Xu, H. S.; Huang, W. H.; Tang, C. X.

2014-01-01

There has been great interest in building compact synchrotrons for various applications, for example, inverse Compton scattering X-ray sources. However, the beam injection and extraction in compact rings require careful design for the lack of space. In this paper, we propose a simple combined injection-extraction scheme exploiting the fringe field of existing dipole magnets instead of additional septum magnets. This scheme is illustrated by using the 4.8 m ring proposed for Tsinghua Thomson scattering X-ray source as an example. Particle tracking is applied to demonstrate the validity of this scheme

Trek and ECCO: Abundance measurements of ultraheavy galactic cosmic rays

International Nuclear Information System (INIS)

Westphal, Andrew J.

2000-01-01

Using the Trek detector, we have measured the abundances of the heaviest elements (with Z>70) in the galactic cosmic rays with sufficient charge resolution to resolve the even-Z elements. We find that the abundance of Pb compared to Pt is ∼3 times lower than the value expected from the most widely-held class of models of the origin of galactic cosmic ray nuclei, that is, origination in a partially ionized medium with solar-like composition. The low abundance of Pb is, however, consistent with the interstellar gas and dust model of Meyer, Drury and Ellison, and with a source enriched in r-process material, proposed by Binns et al. A high-resolution, high-statistics measurement of the abundances of the individual actinides would distinguish between these models. This is the goal of ECCO, the Extremely Heavy Cosmic-ray Composition Observer, which we plan to deploy on the International Space Station

The pulsar contribution to the diffuse galactic gamma-ray emission

DEFF Research Database (Denmark)

Pohl, M.; Kanbach, G.; Hunter, S.D.

1997-01-01

There is active interest in the extent to which unresolved gamma-ray pulsars contribute to the Galactic diffuse emission, and in whether unresolved gamma-ray pulsars could be responsible for the excess of diffuse Galactic emission above 1 GeV that has been observed by EGRET. The diffuse gamma......-ray intensity due to unresolved pulsars is directly linked to the number of objects that should be observed in the EGRET data. We can therefore use our knowledge of the unidentified EGRET sources to constrain model parameters like the pulsar birthrate and their beaming angle. This analysis is based only...... on the properties of the six pulsars that have been identified in the EGRET data and is independent of choice of a pulsar emission model. We find that pulsars contribute very little to the diffuse emission at lower energies, whereas above 1 GeV they can account for 18% of the observed intensity in selected regions...

Analysis of laboratory compaction methods of roller compacted concrete

Science.gov (United States)

Trtík, Tomáš; Chylík, Roman; Bílý, Petr; Fládr, Josef

2017-09-01

Roller-Compacted Concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for laying of asphalt road layers. One of the problems connected with this technology is preparation of representative samples in the laboratory. The aim of this work was to analyse two methods of preparation of RCC laboratory samples with bulk density as the comparative parameter. The first method used dynamic compaction by pneumatic hammer. The second method of compaction had a static character. The specimens were loaded by precisely defined force in laboratory loading machine to create the same conditions as during static rolling (in the Czech Republic, only static rolling is commonly used). Bulk densities obtained by the two compaction methods were compared with core drills extracted from real RCC structure. The results have shown that the samples produced by pneumatic hammer tend to overestimate the bulk density of the material. For both compaction methods, immediate bearing index test was performed to verify the quality of compaction. A fundamental difference between static and dynamic compaction was identified. In static compaction, initial resistance to penetration of the mandrel was higher, after exceeding certain limit the resistance was constant. This means that the samples were well compacted just on the surface. Specimens made by pneumatic hammer actively resisted throughout the test, the whole volume was uniformly compacted.

A Search for New Galactic Magnetars in Archival Chandra and XMM-Newton Observations

Science.gov (United States)

Muno, M. P.; Gaensler, B. M.; Nechita, A.; Miller, J. M.; Slane, P. O.

2008-06-01

We present constraints on the number of Galactic magnetars, which we have established by searching for sources with periodic variability in 506 archival Chandra observations and 441 archival XMM-Newton observations of the Galactic plane (| b| fall within our survey, then there are 59+ 92-32 in the Galaxy. Barely detectable magnetars (LX = 3 × 1033 ergs s-1 and Arms = 15% ) could have been identified throughout ≈0.4% of the spiral arms. The lack of new examples implies that birth rate of magnetars is between 0.003 and 0.06 yr-1. Therefore, the birth rate of magnetars is at least 10% of that for normal radio pulsars, and could exceed that value, unless transient magnetars are active for gtrsim105 yr.

Habitable Evaporated Cores and the Occurrence of Panspermia Near the Galactic Center

Science.gov (United States)

Chen, Howard; Forbes, John C.; Loeb, Abraham

2018-03-01

Black holes growing via the accretion of gas emit radiation that can photoevaporate the atmospheres of nearby planets. Here, we couple planetary structural evolution models of sub-Neptune-mass planets to the growth of the Milky Way’s central supermassive black hole, Sgr A*, and investigate how planetary evolution is influenced by quasar activity. We find that, out to ∼20 pc from Sgr A*, the XUV flux emitted during its quasar phase can remove several percent of a planet’s H/He envelope by mass; in many cases, this removal results in bare rocky cores, many of which are situated in the habitable zones of G-type stars. Near the Galactic Center, the erosion of sub-Neptune-sized planets may be one of the most prevalent channels by which terrestrial super-Earths are created. As such, the planet population demographics may be quite different close to Sgr A* than in the galactic outskirts. The high stellar densities in this region (about seven orders of magnitude greater than the solar neighborhood) imply that the distance between neighboring rocky worlds is short (500–5000 au). The proximity between potentially habitable terrestrial planets may enable the onset of widespread interstellar panspermia near the nuclei of our galaxy. More generally, we predict these phenomena to be ubiquitous for planets in nuclear star clusters and ultra-compact dwarfs. Globular clusters, on the other hand, are less affected by the central black holes.

The Galactic Club or Galactic Cliques? Exploring the limits of interstellar hegemony and the Zoo Hypothesis

Science.gov (United States)

Forgan, Duncan H.

2017-10-01

The Zoo solution to Fermi's Paradox proposes that extraterrestrial intelligences (ETIs) have agreed to not contact the Earth. The strength of this solution depends on the ability for ETIs to come to agreement, and establish/police treaties as part of a so-called `Galactic Club'. These activities are principally limited by the causal connectivity of a civilization to its neighbours at its inception, i.e. whether it comes to prominence being aware of other ETIs and any treaties or agreements in place. If even one civilization is not causally connected to the other members of a treaty, then they are free to operate beyond it and contact the Earth if wished, which makes the Zoo solution `soft'. We should therefore consider how likely this scenario is, as this will give us a sense of the Zoo solution's softness, or general validity. We implement a simple toy model of ETIs arising in a Galactic Habitable Zone, and calculate the properties of the groups of culturally connected civilizations established therein. We show that for most choices of civilization parameters, the number of culturally connected groups is >1, meaning that the Galaxy is composed of multiple Galactic Cliques rather than a single Galactic Club. We find in our models for a single Galactic Club to establish interstellar hegemony, the number of civilizations must be relatively large, the mean civilization lifetime must be several millions of years, and the inter-arrival time between civilizations must be a few million years or less.

Galactic Habitable Zone and Astrobiological Complexity

Science.gov (United States)

Vukotic, B.

2012-12-01

This is a short thesis description and for the sake of brevity most things are left out. For more details, those interested are further directed to the thesis related papers in this article reference list. Thesis itself is available at the University of Belgrade library "Svetozar Markovic" (Serbian version only). In this thesis we study the astrobiological history of the Galactic habitable zone through the means of numerical modeling. First group of simulations are unidimensional (time-axis) toy models examine the influence of global regulation mechanisms (gamma-ray bursts and supernovae) on temporal evolution of Galactic astrobiological complexity. It is shown that under the assumption of global regulation classical anti SETI arguments can be undermined. Second group of simulations are more complex bidimensional probabilistic cellular automata models of the Galactic thin disk. They confirm the findings of the toy models and give some insights into the spatial clustering of astrobiological complexity. As a new emerging multidisciplinary science the basic concepts of astrobiology are poorly understood and although all the simulations present here do not include some basic physics (such as Galactic kinematics and dynamics), the input parameters are somewhat arbitrary and could use a future refinement (such as the boundaries of the Galactic habitable zone). This is the cause for low weight and high uncertainty in the output results of the simulations. However, the probabilistic cellular automata has shown as a highly adaptable modeling platform that can simulate various class of astrobiological models with great ease.

Gravitational Waves and Multi-Messenger Astronomy

Science.gov (United States)

Centrella, Joan M.

2010-01-01

Gravitational waves are produced by a wide variety of sources throughout the cosmos, including the mergers of black hole and neutron star binaries/compact objects spiraling into central black holes in galactic nuclei, close compact binaries/and phase transitions and quantum fluctuations in the early universe. Observing these signals can bring new, and often very precise, information about their sources across vast stretches of cosmic time. In this talk we will focus on thee opening of this gravitational-wave window on the universe, highlighting new opportunities for discovery and multi-messenger astronomy.

FORMATION OF ULTRA-COMPACT BLUE DWARF GALAXIES AND THEIR EVOLUTION INTO NUCLEATED DWARFS

International Nuclear Information System (INIS)

Bekki, Kenji

2015-01-01

We propose that there is an evolutionary link between ultra-compact blue dwarf galaxies (UCBDs) with active star formation and nucleated dwarfs based on the results of numerical simulations of dwarf–dwarf merging. We consider the observational fact that low-mass dwarfs can be very gas-rich, and thereby investigate the dynamical and chemical evolution of very gas-rich, dissipative dwarf–dwarf mergers. We find that the remnants of dwarf–dwarf mergers can be dominated by new stellar populations formed from the triggered starbursts and consequently can have blue colors and higher metallicities (Z ∼ [0.2–1]Z ⊙ ). We also find that the remnants of these mergers can have rather high mass densities (10 4 M ⊙ pc −3 ) within the central 10 pc and small half-light radii (40−100 pc). The radial stellar structures of some merger remnants are similar to those of nucleated dwarfs. Star formation can continue in nuclear gas disks (R < 100 pc) surrounding stellar galactic nuclei (SGNs) so that the SGNs can finally have multiple stellar populations with different ages and metallicities. These very compact blue remnants can be identified as UCBDs soon after merging and as nucleated dwarfs after the young stars fade. We discuss these results in the context of the origins of metal-rich ultra-compact dwarfs and SGNs

FORMATION OF ULTRA-COMPACT BLUE DWARF GALAXIES AND THEIR EVOLUTION INTO NUCLEATED DWARFS

Energy Technology Data Exchange (ETDEWEB)

Bekki, Kenji [ICRAR, M468, The University of Western Australia 35 Stirling Highway, Crawley Western Australia, 6009 (Australia)

2015-10-10

We propose that there is an evolutionary link between ultra-compact blue dwarf galaxies (UCBDs) with active star formation and nucleated dwarfs based on the results of numerical simulations of dwarf–dwarf merging. We consider the observational fact that low-mass dwarfs can be very gas-rich, and thereby investigate the dynamical and chemical evolution of very gas-rich, dissipative dwarf–dwarf mergers. We find that the remnants of dwarf–dwarf mergers can be dominated by new stellar populations formed from the triggered starbursts and consequently can have blue colors and higher metallicities (Z ∼ [0.2–1]Z{sub ⊙}). We also find that the remnants of these mergers can have rather high mass densities (10{sup 4} M{sub ⊙} pc{sup −3}) within the central 10 pc and small half-light radii (40−100 pc). The radial stellar structures of some merger remnants are similar to those of nucleated dwarfs. Star formation can continue in nuclear gas disks (R < 100 pc) surrounding stellar galactic nuclei (SGNs) so that the SGNs can finally have multiple stellar populations with different ages and metallicities. These very compact blue remnants can be identified as UCBDs soon after merging and as nucleated dwarfs after the young stars fade. We discuss these results in the context of the origins of metal-rich ultra-compact dwarfs and SGNs.

Supernovae-generated high-velocity compact clouds

Science.gov (United States)

Yalinewich, A.; Beniamini, P.

2018-05-01

Context. A previous study claimed the discovery of an intermediate-mass black hole (IMBH). This hypothetical black hole was invoked in order to explain the high-velocity dispersion in one of several dense molecular clouds near the Galactic center. The same study considered the possibility that this cloud was due to a supernova explosion, but disqualified this scenario because no X-rays were detected. Aims: We here check whether a supernova explosion could have produced that cloud, and whether this explanation is more likely than an IMBH. More specifically, we wish to determine whether a supernova inside a dense molecular cloud would emit in the X-rays. Methods: We have approached this problem from two different directions. First, we performed an analytic calculation to determine the cooling rate by thermal bremsstrahlung and compared this time to the lifetime of the cloud. Second, we estimated the creation rate of these dense clouds in the central molecular zone (CMZ) region near the Galactic center, where they were observed. Based on this rate, we can place lower bounds on the total mass of IMBHs and clouds and compare this to the masses of the components of the CMZ. Results: We find that the cooling time of the supernova remnant inside a molecular cloud is shorter than its dynamical time. This means that the temperature in such a remnant would be much lower than that of a typical supernova remnant. At such a low temperature, the remnant is not expected to emit in the X-rays. We also find that to explain the rate at which such dense clouds are created requires fine-tuning the number of IMBHs. Conclusions: We find the supernova model to be a more likely explanation for the formation of high-velocity compact clouds than an IMBH.

A search for TeV gamma-ray emission from SNRs, pulsars and unidentified GeV sources in the Galactic plane in the longitude range between -2 deg and 85 deg.

Science.gov (United States)

Aharonian, F. A.; Akhperjanian, A. G.; Beilicke, M.; Bernloehr, K.; Bojahr, H.; Bolz, O.; Boerst, H.; Coarasa, T.; Contreras, J. L.; Cortina, J.; Denninghoff, S.; Fonseca, V.; Girma, M.; Goetting, N.; Heinzelmann, G.; Hermann, G.; Heusler, A.; Hofmann, W.; Horns, D.; Jung, I.; Kankanyan, R.; Kestel, M.; Kettler, J.; Kohnle, A.; Konopelko, A.; Kornmeyer, H.; Kranich, D.; Krawczynski, H.; Lampeitl, H.; Lopez, M.; Lorenz, E.; Lucarelli, F.; Mang, O.; Meyer, H.; Mirzoyan, R.; Moralejo, A.; Ona, E.; Panter, M.; Plyasheshnikov, A.; Puehlhofer, G.; Rauterberg, G.; Reyes, R.; Rhode, W.; Ripken, J.; Roehring, A.; Rowell, G. P.; Sahakian, V.; Samorski, M.; Schilling, M.; Siems, M.; Sobzynska, D.; Stamm, W.; Tluczykont, M.; Voelk, H. J.; Wiedner, C. A.; Wittek, W.

2002-12-01

Using the HEGRA system of imaging atmospheric Cherenkov telescopes, one quarter of the Galactic plane (-2o < l < 85o) was surveyed for TeV gamma-ray emission from point sources and moderately extended sources (φ <= 0.8o). The region covered includes 86 known pulsars (PSR), 63 known supernova remnants (SNR) and nine GeV sources, representing a significant fraction of the known populations. No evidence for emission of TeV gamma radiation was detected, and upper limits range from 0.15 Crab units up to several Crab units, depending on the observation time and zenith angles covered. The ensemble sums over selected SNR and pulsar subsamples and over the GeV-sources yield no indication of emission from these potential sources. The upper limit for the SNR population is 6.7% of the Crab flux and for the pulsar ensemble is 3.6% of the Crab flux.

INTEGRAL/IBIS observations of the Galactic center region at the epoch of the short Fermi/LAT flare

DEFF Research Database (Denmark)

Fiocchi, M.; Sanchez-Fernandez, C.; Natalucci, L.

2011-01-01

, the second one was selected because the source position was most optimal, i.e., about 6-8 degrees off-axis, the closest to the Galactic center region. The second slot is only a few hours apart from the Swift/XRT observation of SAX J1747.0-2853 (ATEL #3163), during which very bright emission from this source...

CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z ∼ 2

International Nuclear Information System (INIS)

Barro, Guillermo; Faber, S. M.; Koo, David C.; Kocevski, Dale D.; Trump, Jonathan R.; Mozena, Mark; McGrath, Elizabeth; Cheung, Edmond; Fang, Jerome; Pérez-González, Pablo G.; Williams, Christina C.; Van der Wel, Arjen; Wuyts, Stijn; Bell, Eric F.; Croton, Darren J.; Ceverino, Daniel; Dekel, Avishai; Ashby, M. L. N.; Ferguson, Henry C.; Fontana, Adriano

2013-01-01

We combine high-resolution Hubble Space Telescope/WFC3 images with multi-wavelength photometry to track the evolution of structure and activity of massive (M * > 10 10 M ☉ ) galaxies at redshifts z = 1.4-3 in two fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We detect compact, star-forming galaxies (cSFGs) whose number densities, masses, sizes, and star formation rates (SFRs) qualify them as likely progenitors of compact, quiescent, massive galaxies (cQGs) at z = 1.5-3. At z ∼> 2, cSFGs present SFR = 100-200 M ☉ yr –1 , yet their specific star formation rates (sSFR ∼ 10 –9 yr –1 ) are typically half that of other massive SFGs at the same epoch, and host X-ray luminous active galactic nuclei (AGNs) 30 times (∼30%) more frequently. These properties suggest that cSFGs are formed by gas-rich processes (mergers or disk-instabilities) that induce a compact starburst and feed an AGN, which, in turn, quench the star formation on dynamical timescales (few 10 8 yr). The cSFGs are continuously being formed at z = 2-3 and fade to cQGs down to z ∼ 1.5. After this epoch, cSFGs are rare, thereby truncating the formation of new cQGs. Meanwhile, down to z = 1, existing cQGs continue to enlarge to match local QGs in size, while less-gas-rich mergers and other secular mechanisms shepherd (larger) SFGs as later arrivals to the red sequence. In summary, we propose two evolutionary tracks of QG formation: an early (z ∼> 2), formation path of rapidly quenched cSFGs fading into cQGs that later enlarge within the quiescent phase, and a late-arrival (z ∼< 2) path in which larger SFGs form extended QGs without passing through a compact state.

The inner 300 parsecs of the Milky Way seen by H.E.S.S.: a Pevatron in the Galactic Centre

Directory of Open Access Journals (Sweden)

Moulin Emmanuel

2017-01-01

Full Text Available The Galactic Centre region has been observed by the High Energy Stereoscopic System (H.E.S.S. array of ground-based Cherenkov telescopes since 2004 leading to the detection of the very-high-energy γ-ray source HESS J1745-290 spatially coincident with the supermassive black hole Sagittarius A*. Diffuse TeV gamma-ray emission has been detected along the Galactic plane, most likely due to hadronic cosmic-ray interactions with the dense gas of the Central Molecular Zone. The rich 2004-2013 dataset permits detailed spectral and morphological studies of the diffuse emission in the inner 300 pc of the Galactic Centre region. The new results provide an important statement regarding the location and origin of the accelerator of PeV protons. The H.E.S.S. observations of the Pevatron are discussed in the context of the origin of Galactic cosmic rays.

Serially Connected Micro Amorphous Silicon Solar Cells for Compact High-Voltage Sources

Directory of Open Access Journals (Sweden)

Jiyoon Nam

2016-01-01

Full Text Available We demonstrate a compact amorphous silicon (a-Si solar module to be used as high-voltage power supply. In comparison with the organic solar module, the main advantages of the a-Si solar module are its compatibility with photolithography techniques and relatively high power conversion efficiency. The open circuit voltage of a-Si solar cells can be easily controlled by serially interconnecting a-Si solar cells. Moreover, the a-Si solar module can be easily patterned by photolithography in any desired shapes with high areal densities. Using the photolithographic technique, we fabricate a compact a-Si solar module with noticeable photovoltaic characteristics as compared with the reported values for high-voltage power supplies.

Imaging and polarimetry of the Galactic Centre in the near-infrared

Energy Technology Data Exchange (ETDEWEB)

Bailey, J; Hough, J H; Axon, D J

1984-06-01

Infrared images of the Galactic Centre with 2.25 arcsec resolution have been obtained at wavelengths of 1.64 ..mu..m (H), 2.2 ..mu..m (K), 3.8 ..mu..m (L') and 4.8 ..mu..m (M). From these, the positions, magnitudes and colours for 35 sources have been measured. The observed sources can be divided into two classes: those whose colours are typical of reddened stars and those with much redder colours which dominate at 3.8 and 4.8 ..mu..m whose infrared radiation is due to dust emission. Polarization measurements for a number of the brighter sources have been made at J, H, and K. Most of the sources with stellar colours show wavelength dependence typical of interstellar polarization with polarizations at K of about 6 per cent.

Imaging and polarimetry of the Galactic Centre in the near-infrared

International Nuclear Information System (INIS)

Bailey, J.; Hough, J.H.; Axon, D.J.

1984-01-01

Infrared images of the Galactic Centre with 2.25 arcsec resolution have been obtained at wavelengths of 1.64 μm (H), 2.2 μm (K), 3.8 μm (L') and 4.8 μm (M). From these, the positions, magnitudes and colours for 35 sources have been measured. The observed sources can be divided into two classes: those whose colours are typical of reddened stars and those with much redder colours which dominate at 3.8 and 4.8 μm whose infrared radiation is due to dust emission. Polarization measurements for a number of the brighter sources have been made at J, H, and K. Most of the sources with stellar colours show wavelength dependence typical of interstellar polarization with polarizations at K of about 6 per cent. (author)

Toward a compact fibered squeezing parametric source.

Science.gov (United States)

Brieussel, Alexandre; Ott, Konstantin; Joos, Maxime; Treps, Nicolas; Fabre, Claude

2018-03-15

In this work, we investigate three different compact fibered systems generating vacuum squeezing that involve optical cavities limited by the end surface of a fiber and by a curved mirror and containing a thin parametric crystal. These systems have the advantage to couple squeezed states directly to a fiber, allowing the user to benefit from the flexibility of fibers in the use of squeezing. Three types of fibers are investigated: standard single-mode fibers, photonic-crystal large-mode-area single-mode fibers, and short multimode fibers taped to a single-mode fiber. The observed squeezing is modest (-0.56  dB, -0.9  dB, -1  dB), but these experiments open the way for miniaturized squeezing devices that could be a very interesting advantage in scaling up quantum systems for quantum processing, opening new perspectives in the domain of integrated quantum optics.

Compact 80-keV neutral-beam module

International Nuclear Information System (INIS)

Molvik, A.W.; Baird, E.D.; Berkner, K.H.; Cooper, W.S.; Duffy, T.J.; Ehlers, K.W.; Fink, J.; Garner, D.; Wilder, C.

1977-01-01

A compact and maintainable source of 80-keV neutral beams that focus to a high power density is required for the Mirror Fusion Test Facility (MFTF). In the new source being designed and built to meet these requirements, the cross-sectional area is reduced in two ways: by immersing the source in a vacuum where high voltage can be held over smaller distances and by redesigning grid supporting structures. Reliability is increased by reducing the electric fields everywhere else below those present between grids and by design innovations. The latter include techniques to reduce stray magnetic field and disperse gas uniformly, all metal-ceramic construction, and a 60-kV shield enclosing all 80-kV electrodes. Wherever possible, we have attempted to simplify the construction. We expect to solve problems that arise during testing either with add-on fixes or with the techniques already tested successfully on the Lawrence Berkeley Laboratory (LBL) 120-keV source. Easy maintenance is obtained by a compact isolation valve and by modular construction. Curving both the grid wires and their holders provides focusing in two planes

X-Ray Timing and Spectral Observations of Galactic Black Hole Candidate XTE J1550--564 During Outburst

Energy Technology Data Exchange (ETDEWEB)

Reilly, Kaice T

2002-12-11

Soft X-ray transients (SXTs), a sub-class of low-mass X-ray binaries (LMXBs), provide a unique opportunity to test General Relativity and to probe fundamental physics under conditions terrestrially unattainable. SXT outbursts are of great interest because they allow the study of LMXBs under a wide range of accretion rates. The majority of known SXTs contain black holes, therefore SXT outbursts are key to understanding accretion physics around black holes and in active galactic nuclei, which are thought to contain supermassive, M {approx} 10{sup 6} - 10{sup 10} M{circle_dot}, where M{circle_dot} is one solar mass, central compact objects. These compact objects are most likely black holes, which exhibit, on a much larger scale, accretion physics similar to that around black holes in SXTs. In this work, the timing and spectral properties of the SXT and microquasar XTE J1550-564 during outburst are studied. Observations made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS) are emphasized. USA data show a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing USA flux and a fractional rms amplitude which is correlated with the USA hardness ratio (4-16 keV/1-4 keV). Several high-frequency quasi-periodic oscillations (HFQPOs) were detected by the Rossi X-ray Timing Explorer (RXTE), during periods where the LFQPO is seen to be weakening or not detectable at all. The evolution of the USA hardness ratio with time and source flux is examined. The hardness-intensity diagram shows counterclockwise cyclical evolution and possibly indicates the presence of two independent accretion flows: a geometrically thin, optically thick accretion disk and a hot sub-Keplerian flow.

AN ABSENCE OF FAST RADIO BURSTS AT INTERMEDIATE GALACTIC LATITUDES

Energy Technology Data Exchange (ETDEWEB)

Petroff, E.; Van Straten, W.; Bailes, M.; Barr, E. D.; Coster, P.; Flynn, C.; Keane, E. F. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Johnston, S. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Bates, S. D.; Keith, M. J.; Kramer, M.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, University of Manchester, Alan Turing Building, Oxford Road, Manchester M13 9PL (United Kingdom); Bhat, N. D. R. [ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), 44 Rosehill Street, Redfern, NSW 2016 (Australia); Burgay, M.; Possenti, A.; Tiburzi, C. [INAF—Osservatorio Astronomico di Cagliari, Via della Scienza, I-09047 Selargius (Italy); Burke-Spolaor, S. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91104 (United States); Champion, D.; Ng, C. [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Levin, L., E-mail: epetroff@astro.swin.edu.au [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); and others

2014-07-10

Fast radio bursts (FRBs) are an emerging class of bright, highly dispersed radio pulses. Recent work by Thornton et al. has revealed a population of FRBs in the High Time Resolution Universe (HTRU) survey at high Galactic latitudes. A variety of progenitors have been proposed, including cataclysmic events at cosmological distances, Galactic flare stars, and terrestrial radio frequency interference. Here we report on a search for FRBs at intermediate Galactic latitudes (–15° Galactic models—must be included to ease the discrepancy between the detection rates at high and low Galactic latitudes. A revised rate estimate or another strong and heretofore unknown selection effect in Galactic latitude would provide closer agreement between the surveys' detection rates. The dearth of detections at low Galactic latitude disfavors a Galactic origin for these bursts.