Multi-mode radio frequency device

DOEpatents

Gilbert, Ronald W [Morgan Hill, CA; Carrender, Curtis Lee [Morgan Hill, CA; Anderson, Gordon A [Benton City, WA; Steele, Kerry D [Kennewick, WA

2007-02-13

A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

A giant radio flare from Cygnus X-3 with associated γ-ray emission

NASA Astrophysics Data System (ADS)

Corbel, S.; Dubus, G.; Tomsick, J. A.; Szostek, A.; Corbet, R. H. D.; Miller-Jones, J. C. A.; Richards, J. L.; Pooley, G.; Trushkin, S.; Dubois, R.; Hill, A. B.; Kerr, M.; Max-Moerbeck, W.; Readhead, A. C. S.; Bodaghee, A.; Tudose, V.; Parent, D.; Wilms, J.; Pottschmidt, K.

2012-04-01

With frequent flaring activity of its relativistic jets, Cygnus X-3 (Cyg X-3) is one of the most active microquasars and is the only Galactic black hole candidate with confirmed high-energy γ-ray emission, thanks to detections by Fermi Large Area Telescope (Fermi/LAT) and AGILE. In 2011, Cyg X-3 was observed to transit to a soft X-ray state, which is known to be associated with high-energy γ-ray emission. We present the results of a multiwavelength campaign covering a quenched state, when radio emission from Cyg X-3 is at its weakest and the X-ray spectrum is very soft. A giant (˜20 Jy) optically thin radio flare marks the end of the quenched state, accompanied by rising non-thermal hard X-rays. Fermi/LAT observations (E≥ 100 MeV) reveal renewed γ-ray activity associated with this giant radio flare, suggesting a common origin for all non-thermal components. In addition, current observations unambiguously show that the γ-ray emission is not exclusively related to the rare giant radio flares. A three-week period of γ-ray emission is also detected when Cyg X-3 was weakly flaring in radio, right before transition to the radio quenched state. No γ-rays are observed during the ˜1-month long quenched state, when the radio flux is weakest. Our results suggest transitions into and out of the ultrasoft X-ray (radio-quenched) state trigger γ-ray emission, implying a connection to the accretion process, and also that the γ-ray activity is related to the level of radio flux (and possibly shock formation), strengthening the connection to the relativistic jets.

A Giant Radio Flare from Cygnus X-3 with Associated Gamma-Ray Emission

NASA Technical Reports Server (NTRS)

Corbel, S.; Dubus, G.; Tomsick, J. A.; Szostek, A.; Corbet, R. H. D.; Miller-Jones, J. C. A.; Richards, J. L.; Pooley, G.; Trushkin, S.; Dubois, R.;

Radio Imaging Observations of Solar Activity Cycle and Its Anomaly

NASA Astrophysics Data System (ADS)

Shibasaki, K.

2011-12-01

The 24th solar activity cycle has started and relative sunspot numbers are increasing. However, their rate of increase is rather slow compared to previous cycles. Active region sizes are small, lifetime is short, and big (X-class) flares are rare so far. We study this anomalous situation using data from Nobeyama Radioheliograph (NoRH). Radio imaging observations have been done by NoRH since 1992. Nearly 20 years of daily radio images of the Sun at 17 GHz are used to synthesize a radio butterfly diagram. Due to stable operation of the instrument and a robust calibration method, uniform datasets are available covering the whole period of observation. The radio butterfly diagram shows bright features corresponding to active region belts and their migration toward low latitude as the solar cycle progresses. In the present solar activity cycle (24), increase of radio brightness is delayed and slow. There are also bright features around both poles (polar brightening). Their brightness show solar cycle dependence but peaks around solar minimum. Comparison between the last minimum and the previous one shows decrease of its brightness. This corresponds to weakening of polar magnetic field activity between them. In the northern pole, polar brightening is already weakened in 2011, which means it is close to solar maximum in the northern hemisphere. Southern pole does not show such feature yet. Slow rise of activity in active region belt, weakening of polar activity during the minimum, and large north-south asymmetry in polar activity imply that global solar activity and its synchronization are weakening.

A Question of Interference: FM Radio's Early Struggle for Survival 1934-1945.

ERIC Educational Resources Information Center

Zenaty, Jayne W.

This paper explores FM radio's struggle for survival in the 1940s, focusing primarily on the impact of Federal Communications Commission (FCC) decision making and on the influence and activities of the well-established radio corporations, primarily the Radio Corporation of America (RCA). It describes the invention of FM radio by Edwin H. Armstrong…

Radio Jove: Jupiter Radio Astronomy for Citizens

NASA Astrophysics Data System (ADS)

Higgins, Charles; Thieman, J. R.; Flagg, R.; Reyes, F. J.; Sky, J.; Greenman, W.; Brown, J.; Typinski, D.; Ashcraft, T.; Mount, A.

2014-01-01

Radio JOVE is a hands-on educational activity that brings the radio sounds of the Sun, Jupiter, the Milky Way Galaxy, and terrestrial radio noise to students, teachers, and the general public. Participants may build a simple radio telescope kit, make scientific observations, and interact with professional radio observatories in real-time over the Internet. Our website (http://radiojove.gsfc.nasa.gov) includes science information, construction manuals, observing guides, and education resources for teachers and students. Radio Jove is continually expanding its participants with over 1800 kits sold to more than 70 countries worldwide. Recently some of our most dedicated observers have upgraded their Radio Jove antennas to semi-professional observatories. We have spectrographs and wide band antennas, some with 8 MHz bandwidth and some with dual polarization capabilities. In an effort to add to the science literature, these observers are coordinating their efforts to pursue some basic questions about Jupiter’s radio emissions (radio source locations, spectral structure, long term changes, etc.). We can compare signal and ionosphere variations using the many Radio Jove observers at different locations. Observers are also working with members of the Long Wavelength Array Station 1 (LWA1) radio telescope to coordinate observations of Jupiter; Radio Jove is planning to make coordinated observations while the Juno Mission is active beginning in 2015. The Radio Jove program is overviewed, its hardware and software are highlighted, recent sample observations are shown, and we demonstrate that we are capable of real citizen science.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1994-01-01

This quarterly publication provides archival reports on developments in programs in space communications, radio navigation, radio science, and ground-based radio and radar astronomy. It reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standardization activities at the Jet Propulsion Laboratory for space data and information systems.

The Radio JOVE Project: Inexpensive Radio Astronomy for the Classroom

NASA Astrophysics Data System (ADS)

Thieman, J. R.; Higgins, C. A.; Pine, W.

2000-12-01

Radio JOVE is an interactive, hands-on educational activity for learning the scientific method through the medium of radio astronomy observations of Jupiter and the sun. Students build a radio telescope from a relatively inexpensive non-profit kit (about \\$125) and use it to record data, analyze the data, and share the results with others. Alternatively, for no cost, the students can record and analyze data from remote radio telescopes connected to the Web. The project is a useful adjunct to activities in optical astronomy since students should recognize that we learn about the Universe through more than just the optical spectrum. In addition to supplementing knowledge of Jupiter and the sun, the project teaches about charged particles and magnetic fields. Building of the kit is also a mini-course in electronics. The Radio JOVE website (http://radiojove.gsfc.nasa.gov) contains science information, instruction manuals, observing guides, software, and education resources for students and teachers.

Sensitive radio survey of obscured quasar candidates

NASA Astrophysics Data System (ADS)

Alexandroff, Rachael M.; Zakamska, Nadia L.; van Velzen, Sjoert; Greene, Jenny E.; Strauss, Michael A.

2016-12-01

We study the radio properties of moderately obscured quasars in samples at both low (z ˜ 0.5) and high (z ˜ 2.5) redshift to understand the role of radio activity in accretion, using the Karl G. Jansky Very Large Array (VLA) at 6.0 GHz and 1.4 GHz. Our z ˜ 2.5 sample consists of optically selected obscured quasar candidates, all of which are radio-quiet, with typical radio luminosities of νLν[1.4 GHz] ≲ 1040 erg s-1. Only a single source is individually detected in our deep (rms˜10 μJy) exposures. This population would not be identified by radio-based selection methods used for distinguishing dusty star-forming galaxies and obscured active nuclei. In our pilot A-array study of z ˜ 0.5 radio-quiet quasars, we spatially resolve four of five objects on scales ˜5 kpc and find they have steep spectral indices with an average value of α = -0.75. Therefore, radio emission in these sources could be due to jet-driven or radiatively driven bubbles interacting with interstellar material on the scale of the host galaxy. Finally, we also study the additional population of ˜200 faint ( ˜ 40 μJy-40 mJy) field radio sources observed over ˜120 arcmin2 of our data. 60 per cent of these detections (excluding our original targets) are matched in the Sloan Digital Sky Survey (SDSS) and/or Wide-Field Infrared Survey Explorer (WISE) and are, in roughly equal shares, active galactic nuclei (AGN) at a broad range of redshifts, passive galaxies with no other signs of nuclear activity and infrared-bright but optically faint sources. Spectroscopically or photometrically confirmed star-forming galaxies constitute only a small minority of the matches. Such sensitive radio surveys allow us to address important questions of AGN evolution and evaluate the AGN contribution to the radio-quiet sky.

Radio emission in the directions of cD and related galaxies in poor clusters. III. VLA observations at 20 cm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burns, J.O.; White, R.A.; Hough, D.H.

1981-01-01

VLA radio maps and optical identifications of a sample of sources in the directions of 21 Yerkes poor cluster fields are presented. The majority of the cluster radio sources are associated with the dominant D or cD galaxies (approx.70%). Our analysis of dominant galaxies in rich and poor clusters indicates that these giant galaxies are much more often radio emitters (approx.25% of cD's are radio active in the poor clusters), have steeper radio spectra, and have simpler radio morphologies (i.e., double or other linear structure) than other less bright ellipticals. A strong continuum of radio properties in cD galaxies ismore » seen from rich to poor clusters. We speculate that the location of these dominant galaxies at the cluster centers (i.e., at the bottom of a deep, isolated gravitational potential well) is the crucial factor in explaining their multifrequency activity. We briefly discuss galaxy cannibalism and gas infall models as fueling mechanisms for the observed radio and x-ray emission.« less

Radio emission in the directions of cD and related galaxies in poor clusters. III - VLA observations at 20 cm

NASA Technical Reports Server (NTRS)

Burns, J. O.; White, R. A.; Hough, D. H.

1981-01-01

VLA radio maps and optical identifications of a sample of sources in the directions of 21 Yerkes poor cluster fields are presented. The majority of the cluster radio sources are associated with the dominant D or cD galaxies (approximately 70 percent). Our analysis of dominant galaxies in rich and poor clusters indicates that these giant galaxies are much more often radio emitters (approximately 25 percent of cD's are radio active in the poor clusters), have steeper radio spectra, and have simpler radio morphologies (i.e., double or other linear structure) than other less bright ellipticals. A strong continuum of radio properties in cD galaxies is seen from rich to poor clusters. It is speculated that the location of these dominant galaxies at the cluster centers (i.e., at the bottom of a deep, isolated gravitational potential well) is the crucial factor in explaining their multifrequency activity. Galaxy cannibalism and gas infall models as fueling mechanisms for the observed radio and X-ray emission are discussed

Radio Jove: Citizen Science for Jupiter Radio Astronomy

NASA Astrophysics Data System (ADS)

Higgins, C. A.; Thieman, J.; Reyes, F. J.; Typinski, D.; Flagg, R. F.; Greenman, W.; Brown, J.; Ashcraft, T.; Sky, J.; Cecconi, B.; Garcia, L. N.

2016-12-01

The Radio Jove Project (http://radiojove.gsfc.nasa.gov) has been operating as an educational activity for 18 years to introduce radio astronomy activities to students, teachers, and the general public. Participants may build a simple radio telescope kit, make scientific observations, and interact with radio observatories in real-time over the Internet. Recently some of our dedicated citizen science observers have upgraded their systems to better study radio emission from Jupiter and the Sun by adding dual-polarization spectrographs and wide-band antennas in the frequency range of 15-30 MHz. Some of these observations are being used in conjunction with professional telescopes such as the Long Wavelength Array (LWA), the Nancay Decametric Array, and the Ukrainian URAN2 Radio Telescope. In particular, there is an effort to support the Juno Mission radio waves instrument at Jupiter by using citizen science ground-based data for comparison and polarization verification. These data will be archived through a Virtual European Solar and Planetary Access (VESPA) archive (https://voparis-radiojove.obspm.fr/radiojove/welcome) for use by the amateur and professional radio science community. We overview the program and display recent observations that will be of interest to the science community.

COLA. III. Radio Detection of Active Galactic Nucleus in Compact Moderate Luminosity Infrared Galaxies

NASA Astrophysics Data System (ADS)

Parra, R.; Conway, J. E.; Aalto, S.; Appleton, P. N.; Norris, R. P.; Pihlström, Y. M.; Kewley, L. J.

2010-09-01

We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L IR = 1011.01 L sun) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~1021 W Hz-1) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.

The Miners' Radio Stations in Bolivia: A Culture of Resistance.

ERIC Educational Resources Information Center

O'Connor, Alan

1990-01-01

Examines local community radio stations in rural regions of Bolivia. Finds that active miners' radio has flourished as an entertainment and political medium and that, through their radio stations, miners' organizations have played an important role in shaping the political position of the Bolivian union movement. (KEH)

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1985-01-01

Reports on developments in space communications, radio navigation, radio science, and ground-based radio astronomy are presented. Activities of the Deep Space Network (DSN) are reported in the areas of planning, supporting research and technology, implementation and operations. The application of radio interferometry at microwave frequencies for geodynamic measurements is also discussed.

Accurate radio and optical positions for the radio star HD 36705 (AB Doradus)

NASA Technical Reports Server (NTRS)

White, Graeme L.; Jauncey, David L.; Batty, Michael J.; Peters, W. L.; Gulkis, S.

1988-01-01

Arc-second position measurements of the active star HD 36705 (AB Dor) and of the variable radio source found nearby are presented. These measurements show that the radio source is clearly identified with HD 36705 and not with the nearby red-dwarf star Rst 137B.

Renewed Radio Activity of Age 370 years in the Extragalactic Source 0108+388

NASA Astrophysics Data System (ADS)

Owsianik, I.; Conway, J. E.; Polatidis, A. G.

1998-08-01

We present the results of multi-epoch global VLBI observations of the Compact Symmetric Object (CSO) 0108+388 at 5 GHz. Analysis of data spread over 12 years shows strong evidence for an increase in the separation of the outer components at a rate of 0.197+/-0.026 h(-1) c. Given an overall size of 22.2 h(-1) pc this implies a kinematic age of only 367+/-48 yrs. This result strongly supports the idea that radio emission in Compact Symmetric Objects arises from recently activated radio sources. The presence of weak radio emission on kpc-scales in 0108+388 suggests recurrent activity in this source, and that we are observing it just as a new period of activity is beginning.

LOFAR/H-ATLAS: the low-frequency radio luminosity-star formation rate relation

NASA Astrophysics Data System (ADS)

Gürkan, G.; Hardcastle, M. J.; Smith, D. J. B.; Best, P. N.; Bourne, N.; Calistro-Rivera, G.; Heald, G.; Jarvis, M. J.; Prandoni, I.; Röttgering, H. J. A.; Sabater, J.; Shimwell, T.; Tasse, C.; Williams, W. L.

2018-04-01

Radio emission is a key indicator of star formation activity in galaxies, but the radio luminosity-star formation relation has to date been studied almost exclusively at frequencies of 1.4 GHz or above. At lower radio frequencies, the effects of thermal radio emission are greatly reduced, and so we would expect the radio emission observed to be completely dominated by synchrotron radiation from supernova-generated cosmic rays. As part of the LOFAR Surveys Key Science project, the Herschel-ATLAS NGP field has been surveyed with LOFAR at an effective frequency of 150 MHz. We select a sample from the MPA-JHU catalogue of Sloan Digital Sky Survey galaxies in this area: the combination of Herschel, optical and mid-infrared data enable us to derive star formation rates (SFRs) for our sources using spectral energy distribution fitting, allowing a detailed study of the low-frequency radio luminosity-star formation relation in the nearby Universe. For those objects selected as star-forming galaxies (SFGs) using optical emission line diagnostics, we find a tight relationship between the 150 MHz radio luminosity (L150) and SFR. Interestingly, we find that a single power-law relationship between L150 and SFR is not a good description of all SFGs: a broken power-law model provides a better fit. This may indicate an additional mechanism for the generation of radio-emitting cosmic rays. Also, at given SFR, the radio luminosity depends on the stellar mass of the galaxy. Objects that were not classified as SFGs have higher 150-MHz radio luminosity than would be expected given their SFR, implying an important role for low-level active galactic nucleus activity.

Solar-geophysical data number 499, March 1986. Part 1: (Prompt reports). Data for February 1986, January 1986 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E. (Editor)

1986-01-01

Solar-Geophysical Data Number 499, March 1986, Part 1 (Prompt Reports); Data for February 1986, January 1986 and Late Data, contains the following: Detailed index for 1985 to 1986; Data for February 1986--(IUWDS alert periods (Advance and worldwide), Solar activity indices, Solar flares, Solar radio emission, Vostok inferred interplanetary magnetic field polarity, Stanford mean solar magnetic field); data for January 1986--(Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices, Radio propagation indices); Late data-(Solar active regions, Solar radio spectral observations Culgoora, Cosmic ray measurements by neutron monitor, Calcium plage data).

Quantification of Rock Damage from Small Explosions and Its Effect on Shear-Wave Generation

DTIC Science & Technology

2009-06-15

close to a nearby cell /radio tower and the active quarry wall to detonate our planned 400 lb explosions. Core drilling at an alternative test site...Figure ) was conducted further away from the active quarry wall and a nearby cell /radio tower. The alternative site would be far enough away from...returned into the original location (Figure ). In order to reduce the projected ground vibrations at the cell /radio tower and high wall of the active

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padovani, P.; Mainieri, V.; Rosati, P.

2011-10-10

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 {mu}Jy at the field center and redshift {approx}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-millijanskymore » 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 {approx}> 3 x 10{sup 24} W Hz{sup -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 {approx}30% of the sample and {approx}60% of all AGNs, and outnumbering radio-loud AGNs at {approx}< 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.« less

Particle content, radio-galaxy morphology, and jet power: all radio-loud AGN are not equal

NASA Astrophysics Data System (ADS)

Croston, J. H.; Ineson, J.; Hardcastle, M. J.

2018-05-01

Ongoing and future radio surveys aim to trace the evolution of black hole growth and feedback from active galactic nuclei (AGNs) throughout cosmic time; however, there remain major uncertainties in translating radio luminosity functions into a reliable assessment of the energy input as a function of galaxy and/or dark matter halo mass. A crucial and long-standing problem is the composition of the radio-lobe plasma that traces AGN jet activity. In this paper, we carry out a systematic comparison of the plasma conditions in Fanaroff & Riley class I and II radio galaxies to demonstrate conclusively that their internal composition is systematically different. This difference is best explained by the presence of an energetically dominant proton population in the FRI, but not the FRII radio galaxies. We show that, as expected from this systematic difference in particle content, radio morphology also affects the jet-power/radio-luminosity relationship, with FRII radio galaxies having a significantly lower ratio of jet power to radio luminosity than the FRI cluster radio sources used to derive jet-power scaling relations via X-ray cavity measurements. Finally, we also demonstrate conclusively that lobe composition is unconnected to accretion mode (optical excitation class): the internal conditions of low- and high-excitation FRII radio lobes are indistinguishable. We conclude that inferences of population-wide AGN impact require careful assessment of the contribution of different jet subclasses, particularly given the increased diversity of jet evolutionary states expected to be present in deep, low-frequency radio surveys such as the LOFAR Two-Metre Sky Survey.

The Telecommunications and Data Acquisition Report. [Deep Space Network

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1988-01-01

In space communications, radio navigation, radio science, and ground based radio and radar astronomy, activities of the Deep Space Network and its associated Ground Communications Facility in planning, in supporting research and technology, in implementation, and in operations are reported. Also included is TDA funded activity at JPL on data and information systems and reimbursable DSN work performed for other space agencies through NASA.

Automated isotope identification algorithm using artificial neural networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamuda, Mark; Stinnett, Jacob; Sullivan, Clair

There is a need to develop an algorithm that can determine the relative activities of radio-isotopes in a large dataset of low-resolution gamma-ray spectra that contains a mixture of many radio-isotopes. Low-resolution gamma-ray spectra that contain mixtures of radio-isotopes often exhibit feature over-lap, requiring algorithms that can analyze these features when overlap occurs. While machine learning and pattern recognition algorithms have shown promise for the problem of radio-isotope identification, their ability to identify and quantify mixtures of radio-isotopes has not been studied. Because machine learning algorithms use abstract features of the spectrum, such as the shape of overlapping peaks andmore » Compton continuum, they are a natural choice for analyzing radio-isotope mixtures. An artificial neural network (ANN) has be trained to calculate the relative activities of 32 radio-isotopes in a spectrum. Furthermore, the ANN is trained with simulated gamma-ray spectra, allowing easy expansion of the library of target radio-isotopes. In this paper we present our initial algorithms based on an ANN and evaluate them against a series measured and simulated spectra.« less

Automated isotope identification algorithm using artificial neural networks

DOE PAGES

Kamuda, Mark; Stinnett, Jacob; Sullivan, Clair

2017-04-12

There is a need to develop an algorithm that can determine the relative activities of radio-isotopes in a large dataset of low-resolution gamma-ray spectra that contains a mixture of many radio-isotopes. Low-resolution gamma-ray spectra that contain mixtures of radio-isotopes often exhibit feature over-lap, requiring algorithms that can analyze these features when overlap occurs. While machine learning and pattern recognition algorithms have shown promise for the problem of radio-isotope identification, their ability to identify and quantify mixtures of radio-isotopes has not been studied. Because machine learning algorithms use abstract features of the spectrum, such as the shape of overlapping peaks andmore » Compton continuum, they are a natural choice for analyzing radio-isotope mixtures. An artificial neural network (ANN) has be trained to calculate the relative activities of 32 radio-isotopes in a spectrum. Furthermore, the ANN is trained with simulated gamma-ray spectra, allowing easy expansion of the library of target radio-isotopes. In this paper we present our initial algorithms based on an ANN and evaluate them against a series measured and simulated spectra.« less

Winds as the origin of radio emission in z = 2.5 radio-quiet extremely red quasars

NASA Astrophysics Data System (ADS)

Hwang, Hsiang-Chih; Zakamska, Nadia L.; Alexandroff, Rachael M.; Hamann, Fred; Greene, Jenny E.; Perrotta, Serena; Richards, Gordon T.

2018-06-01

Most active galactic nuclei (AGNs) are radio quiet, and the origin of their radio emission is not well understood. One hypothesis is that this radio emission is a byproduct of quasar-driven winds. In this paper, we present the radio properties of 108 extremely red quasars (ERQs) at z = 2-4. ERQs are among the most luminous quasars (Lbol ˜ 1047-48 erg s-1) in the Universe, with signatures of extreme (≫1000 km s-1) outflows in their [O III]λ5007 Å emission, making them the best subjects to seek the connection between radio and outflow activities. All ERQs but one are unresolved in the radio on ˜10 kpc scales, and the median radio luminosity of ERQs is νLν[6 GHz] = 1041.0 erg s-1, in the radio-quiet regime, but 1-2 orders of magnitude higher than that of other quasar samples. The radio spectra are steep, with a mean spectral index <α> = -1.0. In addition, ERQs neatly follow the extrapolation of the low-redshift correlation between radio luminosity and the velocity dispersion of [O III]-emitting ionized gas. Uncollimated winds, with a power of one per cent of the bolometric luminosity, can account for all these observations. Such winds would interact with and shock the gas around the quasar and in the host galaxy, resulting in acceleration of relativistic particles and the consequent synchrotron emission observed in the radio. Our observations support the picture in which ERQs are signposts of extremely powerful episodes of quasar feedback, and quasar-driven winds as a contributor of the radio emission in the intermediate regime of radio luminosity νLν = 1039-1042 erg s-1.

COLA. III. RADIO DETECTION OF ACTIVE GALACTIC NUCLEUS IN COMPACT MODERATE LUMINOSITY INFRARED GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parra, R.; Conway, J. E.; Aalto, S.

2010-09-01

We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L{sub IR} = 10{sup 11.01} L{sub sun}) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores ({approx}10{sup 21} W Hz{sup -1}) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whosemore » VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.« less

Solar-Geophysical Data Number 496, February 1986. Part 1: (Prompt reports). Data for January 1986,December 1985 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E.

1986-01-01

Solar-Geophysical Data Number 498, February 1986, Part 1 (Prompt Reports), Data for January 1986, December 1985 and Late Data contains the following:detailed index for 1985-86; data for January 1986--(IUWDS alert periods (advanced and worldwide), Solar activity indices, Solar flares, Solar radio emission, Vostok inferred interplanetary magnetic field polarity, Stanford mean solar magnetic field); data for December 1985--(Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices, Radio propagation indices); late data--(Solar radio emission Nancay interferometric chart December 1985, Solar radio spectral observations Culgoora May 1985, Geomagnetic indices sudden commencements November 1985, Calcium plage data).

The BL LAC phenomenon: X-ray observations of transition objects and determination of the x-ray spectrum of a complete sample of flat-spectrum radio sources

NASA Technical Reports Server (NTRS)

Worrall, Diana M.

1994-01-01

This report summarizes the activities related to two ROSAT investigations: (1) x-ray properties of radio galaxies thought to contain BL Lac type nuclei; and (2) x-ray spectra of a complete sample of flat-spectrum radio sources. The following papers describing the research are provided as attachments: Multiple X-ray Emission Components in Low Power Radio Galaxies; New X-ray Results on Radio Galaxies; Analysis Techniques for a Multiwavelength Study of Radio Galaxies; Separation of X-ray Emission Components in Radio Galaxies; X-ray Emission in Powerful Radio Galaxies and Quasars; Extended and Compact X-ray Emission in Powerful Radio Galaxies; and X-ray Spectra of a Complete Sample of Extragalactic Core-dominated Radio Sources.

Prospects and limitations for use of frequency spectrum from 40 to 300 GHz

NASA Technical Reports Server (NTRS)

Catoe, C. E.

1979-01-01

The existing and future use of the electromagnetic spectrum from 40 to 300 gigahertz is discussed. The activities envisioned for this segment of the electromagnetic spectrum fall generically into two basic categories: communications and remote sensing. The communications services considered for this region are focused on the existing and future frequency allocations that are required for terrestrial radio services, space to ground radio services, space to space radio services, and space to deep space radio services. The remote sensing services considered for this region are divided into two groups of activities: earth viewing and space viewing.

An overview and guide: planning instructional radio.

PubMed

Imhoof, M

1984-03-01

Successful instructional radio projects require both comprehensive and complex planning. The instructional radio planning team needs to have knowledge and capabilities in several technical, social, and educational areas. Among other skills, the team must understand radio, curriculum design, the subject matter being taught, research and evaluation, and the environment in which the project operates. Once a basic approach to educational planning has been selected and broad educational goals set, radio may be selected as a cost effective means of achieving some of the goals. Assuming radio is a wise choice, there are still several factors which must be analyzed by a team member who is a radio specialist. The most obvious consideration is the inventory and evaluation of the facilities: studios; broadcast, recording, and transmission equipment; classroom radios; and so on. Capabilities of broadcast personnel are another consideration. Initial radio lessons need to teach the learners how to listen to the radio if they have no previous experience with institutional radio broadcasts. A captive, inschool audience ready to listen to radio instructions requires a different use of the medium than a noncaptive audience. With the noncaptive audience, the educational broadcaster must compete with entertaining choices from other media and popular activities and pastimes of the community. The most complex knowledge and analysis required in planning instructional radio concerns the relationship of the content to the medium. Environmental factors are important in planning educational programs. The physical environment may present several constraints on the learning experience and the use of radio. The most obvious is the effect of climate and terrain on the quality of radio reception. The physical environment is easily studied through experience in the target area, but this knowledge plays a significant role in designing effective learning materials for specific learners. Social activities utilized in broadcasts which are contrary to the learners' experience will at best seem strange and at worst be incomprehensible. Curriculum development in an instructional radio project adds more complexity to the planner's task. The most important information needed is whether a new curriculum is to be developed or whether the existing curriculum is to be adapted for radio. Another major analysis task is relating the curriculum to the medium. The project planning team needs to understand the research aims and evaluation methods in instructional radio projects. Sometimes an outside evaluation specialist or team is employed, but in many projects the planning team is responsible for implementing the research design, carrying out the development activities, gathering data, and evaluating the project. Subject matter testing is another technical area of expertise needed by the project team.

A census of radio-selected AGNs on the COSMOS field and of their FIR properties

NASA Astrophysics Data System (ADS)

Magliocchetti, M.; Popesso, P.; Brusa, M.; Salvato, M.

2018-01-01

We use the new catalogue by Laigle et al. to provide a full census of VLA-COSMOS radio sources. We identify 90 per cent of such sources and sub-divide them into active galactic nuclei (AGNs) and star-forming galaxies on the basis of their radio luminosity. The AGN sample is complete with respect to radio selection at all z ≲ 3.5. Out of 704 AGNs, 272 have a counterpart in the Herschel maps. By exploiting the better statistics of the new sample, we confirm the results of Magliocchetti et al.: the probability for a radio-selected AGN to be detected at far-infrared (FIR) wavelengths is both a function of radio luminosity and redshift, whereby powerful sources are more likely FIR emitters at earlier epochs. Such an emission is due to star-forming processes within the host galaxy. FIR emitters and non-FIR emitters only differentiate in the z ≲ 1 universe. At higher redshifts, they are indistinguishable from each other, as there is no difference between FIR-emitting AGNs and star-forming galaxies. Lastly, we focus on radio AGNs which show AGN emission at other wavelengths. We find that mid-infrared (MIR) emission is mainly associated with ongoing star formation and with sources which are smaller, younger and more radio luminous than the average parent population. X-ray emitters instead preferentially appear in more massive and older galaxies. We can therefore envisage an evolutionary track whereby the first phase of a radio-active AGN and of its host galaxy is associated with MIR emission, while at later stages the source becomes only active at radio wavelengths and possibly also in the X-ray.

ISSPO Educational Outreach through Educational Program Cooperation

NASA Technical Reports Server (NTRS)

Conley, Carolynn

2004-01-01

The International Space Station Program Office (ISSPO) has organized a consolidated program to provide communication, education, and outreach to the general public. Existing space station education programs, including amateur radio activities on ISS done voluntarily by the crew members, can be linked to additional classroom and field activities, multiplying the impact of this very scarce and valuable Station resource. Linkages could be created between programs such as Starshine, Space Camp Turkey, MISSES/PCSAT2, and Amateur Radio on ISS. In addition, Amateur radio provides a means of introducing school children to technical hardware and concepts while being fun for the youthful mind. Amateur radio can reach the worldwide community while remaining within very affordable budgets of schools and individuals. When the radio communication is coupled with the Internet, the effect is even greater. People in many diverse areas of the world have access to the internet or radio.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1993-01-01

Reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) are provided. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other agencies through NASA.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1994-01-01

Reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) are provided. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other agencies through NASA.

Solar-geophysical data number 493, September 1985. Part 1: (Prompt reports). Data for August 1985, July 1985 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E. (Editor)

1985-01-01

Topics covered include: detailed index for 1985; data for August 1985--(IUWDS alert periods (Advanced and Worldwide), solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field); (solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements by neutron monitor, geomagnetic indices, radio propagation indices); and late data--calcium plage data.

Solar-geophysical data number 494, October 1985. Part 1: (Prompt reports). Data for September 1985, August 1985 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E. (Editor)

1985-01-01

Data for August and September 1985 on IUWDS alert periods (advance and worldwide), solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic fields, solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements, geomagnetic indices, radio porpagation indices, inferred interplanetary magnetic field polarity, preliminary solar proton event list, and calcium plage are presented.

Seasonal variations of mesopause temperature and the amplitude of the VLF signals of the Novosibirsk radio station during 2009-2016

NASA Astrophysics Data System (ADS)

Korsakov, Alexey; Kozlov, Vladimir; Ammosova, Anastasia; Ammosov, Petr; Gavrilyeva, Galina; Koltovskoi, Igor; Pavlov, Yegor

2017-10-01

Dynamics of seasonal variations of the amplitude of the VLF radio signal received in Yakutsk from the navigation station near Novosibirsk and the P-branches of the OH band (6-2) radiation intensity in the wavelength range 835 - 853 nm are considered. The radiation variations give information about mesopause region measured at the Maimaga station (130 km from Yakutsk). The observation from 2009 to 2016 covers period with minimum and maximum solar activity. The mesopause temperature and the VLF signal increase with increasing solar flux F10.7 in winter. The mesopause temperature seasonal variations and the VLF signal strength for the Novosibirsk-Yakutsk path are regularly inverted from year to year. By decade data averaging the VLF radio signal strength dependence on the temperature of the atmosphere at the OH excitation height can be expressed by a linear function. The coefficient of determination: R2 = 0.59, the anticorrelation coefficient: r10 = - 0.77. The variations of the VLF radio noise and the radio station signal for the eight-year interval are similar to solar activity (F10.7 index). The signal level of the radio station and radio noise registered in the winter is more sensitive to variations of F10.7 index in 24th solar cycle activity.

Goldstone-Apple Valley Radio Telescope System Theory of Operation

NASA Technical Reports Server (NTRS)

Stephan, George R.

1997-01-01

The purpose of this learning module is to enable learners to describe how the Goldstone-Apple Valley Radio Telescope (GAVRT) system functions in support of Apple Valley Science and Technology Center's (AVSTC) client schools' radio astronomy activities.

Relationship Between the Radio Bursts from the Sun and Ionospheric Propagation

NASA Astrophysics Data System (ADS)

West, Mary Lou; Frissell, N.; Papalos, M.

2006-12-01

We are monitoring the sun’s radio activity at 20.1 MHz with a Radio Jove rig, and have begun to monitor the Earth’s ionosphere for HF radio propagation using the worldwide network of beacons set up by the Northern California DX Foundation. These 18 beacons transmit at 14.1, 18.11, 21.15, 24.93, and 28.2 MHz on a 3 minute cadence and allow ham radio operators to judge the radio propagation characteristics to distant lands easily. Although the solar activity cycle is now near its bottom, there are occasional outbursts, some spectacular. August 29, 2006, was such a day, prompting the Radio Jove community to post ten times the usual number of reports to the archive at Goddard Space Flight Center. The next day the Earth’s ionosphere suddenly blossomed with HF openings without any X-ray flares reported. The delay time of 26 hours from the most energetic radio event indicated a velocity of 1600 km/s, normal for a coronal mass ejection. Several other events have also shown delays of about 24 hours from the radio sun to the ionosphere, and are especially noticeable at the higher frequency bands and on the events list of the Space Environment Center of NOAA. The 20.1 MHz monitors may serve as a method to predict radio propagation properties of the ionosphere more quickly than previous methods.

Reflections on works by I.S.Shklovsky regarding the nature of radio galaxies

NASA Astrophysics Data System (ADS)

Komberg, B. V.; Zhuravlev, V. I.

The paper is a brief overview of the works by Iosif S. Shklovsky (1916-1985), carried out over almost 30 years (1955-1985), on the nature of activity (primarily in the radio frequency range) in nuclei of some galaxies. Worthy of note is Shklovsky's pioneering work of 1962, in which he made an attempt to consider possible evolutionary tracks of extragalactic radio sources by constructing an analog of the Herzsprung-Russel diagram for stars (radio luminosity at 160 MHz was taken instead of optical luminosity; total radio size at the same frequency, as the other parameter). Later works by other authors are also discussed, where similar diagrams were plotted using a larger observational material. Special attention is paid to the evolution of Shklovsky's views regarding the possible ways of gas getting into radio galaxies' central regions, followed by high-velocity ejections of magnetized plasmons from their nuclei. Shklovsky's assumptions were mainly based on the observational data for the properties of the closest radio galaxy, NGC 4486 (Virgo A, M87), which he believed to be the same reference standard for extragalactic radio astronomy as the Crab Nebula for galactic radio astronomy. Shklovsky's approach to the recurrence of the activity phenomenon in galactic nuclei and the one-sided character of radio ejections from them is discussed. Modern views on these issues are also briefly considered.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1993-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA.

Cooperation Helps Power Saving

DTIC Science & Technology

2009-04-07

the destination node hears the poll, the link between the two nodes is activated. In the original STEM, two radios working on two separate channels... hears the poll, the link between the two nodes is activated. In the original STEM, two radios working on two separate chan- nels are used: one radio is...Computer and Communications Societies. Proceedings. IEEE, vol. 3, pp. 1548–1557 vol.3, 2001. [2] R . Kravets and P. Krishnan, “Application-driven power

AGN Feedback And Evolution of Radio Sources: Discovery of An X-Ray Cluster Associated With Z=1 Quasar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemiginowska, Aneta; /Harvard-Smithsonian Ctr. Astrophys.; Cheung, C.C.

2006-01-11

We report the first significant detection of an X-ray cluster associated with a powerful (L{sub bol} {approx} 10{sup 47} erg sec{sup -1}) radio-loud quasar at high redshift (z=1.06). Diffuse X-ray emission is detected out to {approx} 120 kpc from the CSS quasar 3C 186. A strong Fe-line emission at the z{sub rest} = 1.06 confirms its thermal nature. We find that the CSS radio source is highly overpressured with respect to the thermal cluster medium by 2-3 orders of magnitude. This provides direct observational evidence that the radio source is not thermally confined as posited in the ''frustrated'' scenario formore » CSS sources. Instead, the radio source may be young and at an early stage of its evolution. This source provides the first detection of the AGN in outburst in the center of a cooling flow cluster. Powerful radio sources are thought to be triggered by the cooling flows. The evidence for the AGN activity and intermittent outbursts comes from the X-ray morphology of low redshift clusters, which usually do not harbour quasars. 3C186 is a young active radio source which can supply the energy into the cluster and potentially prevent its cooling. We discuss energetics related to the quasar activity and the cluster cooling flow, and possible feedback between the evolving radio source and the cluster.« less

AGN ACTIVITY AND IGM HEATING IN THE FOSSIL CLUSTER RX J1416.4+2315

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miraghaei, H.; Khosroshahi, H. G.; Abbassi, S.

2015-12-15

We study active galactic nucleus (AGN) activity in the fossil galaxy cluster RX J1416.4+2315. Radio observations were carried out using the Giant Metrewave Radio Telescope at two frequencies, 1420 and 610 MHz. A weak radio lobe that extends from the central nucleus is detected in the 610 MHz map. Assuming the radio lobe originated from the central AGN, we show that the energy injection into the intergalactic medium is only sufficient to heat up the central 50 kpc within the cluster core, while the cooling radius is larger (∼130 kpc). In the hardness ratio map, three low energy cavities havemore » been identified. No radio emission is detected for these regions. We evaluated the power required to inflate the cavities and showed that the total energy budget is sufficient to offset the radiative cooling. We showed that the initial conditions would change the results remarkably. Furthermore, the efficiency of the Bondi accretion in powering the AGN has been estimated.« less

The Cost-Effectiveness of Interactive Radio Instruction for Improving Primary School Instruction in Honduras, Bolivia and Lesotho.

ERIC Educational Resources Information Center

Tilson, Thomas D.; And Others

Findings are presented from studies on the use of radio for teaching primary school children mathematics in Honduras and Bolivia and English as a Second Language in Lesotho. Interactive radio instruction (IRI) is so called because of the active participation of the students. Although lessons are presented by conventional radio, scripts are written…

Nature of radio feature formed by re-started jet activity in 3C 84 and its relation with γ-ray emissions

NASA Astrophysics Data System (ADS)

Nagai, H.; Chida, H.; Kino, M.; Orienti, M.; D'Ammando, F.; Giovannini, G.; Hiura, K.

2016-02-01

Re-started jet activity occurred in the bright nearby radio source 3C 84 in about 2005. The re-started jet is forming a prominent component (namely C3) at the tip of jet. The component has showed an increase in radio flux density for more than 7 years while the radio spectrum remains optically thin. This suggests that the component is the head of a radio lobe including a hotspot where the particle acceleration occurs. Thus, 3C 84 is a unique laboratory to study the physical properties at the very early stage of radio source evolution. Another important aspect is that high energy and very high energy γ-ray emissions are detected from this source. The quest for the site of γ-ray emission is quite important to obtain a better understanding of γ-ray emission mechanisms in radio galaxies. In this paper, we review the observational results from very long baseline interferometry (VLBI) monitoring of 3C 84 reported in series of our previous papers. We argue the nature of re-started jet/radio lobe and its relation with high-energy emission.

47 CFR 90.31 - Scope.

Code of Federal Regulations, 2010 CFR

2010-10-01

... licensing of the radio communications of entities engaged in commercial activities, engaged in clergy... FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO..., permissible communications and classes and number of stations, and any special requirements are set forth in...

A VLA radio continuum survey of active late-type giants in binary systems - Preliminary results

NASA Technical Reports Server (NTRS)

Drake, S. A.; Simon, T.; Linsky, J. L.

1985-01-01

Preliminary results of a 6 cm continuum survey using the NRAO VLA of binary systems with 10-100 day orbital period containing an 'active' giant component are reported. The results show that strong radio continuum emission at centimeter wavelengths is a common but not universal property of this class of stars. Possible correlations between radio luminosity and other properties, such as X-ray luminosity, rotational period, and type of companion are discussed. Several binary systems which have been detected for the first time as radio sources are reported, and sensitive upper limits are presented for five other systems, including Capella.

47 CFR 95.1 - The General Mobile Radio Service (GMRS).

Code of Federal Regulations, 2010 CFR

2010-10-01

...-way communications to facilitate the activities of licensees and their immediate family members. Each... Section 95.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO... radio service authorized for system licensees to provide communication service to subscribers in a...

Learning radio astronomy by doing radio astronomy

NASA Astrophysics Data System (ADS)

Vaquerizo Gallego, J. A.

2011-11-01

PARTNeR (Proyecto Académico con el Radio Telescopio de NASA en Robledo, Academic Project with the NASA Radio Telescope at Robledo) is an educational program that allows high school and undergraduate students to control a 34 meter radio telescope and conduct radio astronomical observations via the internet. High-school teachers who join the project take a course to learn about the science of radio astronomy and how to use the antenna as an educational resource. Also, teachers are provided with learning activities they can do with their students and focused on the classroom implementation of the project within an interdisciplinary framework. PARTNeR provides students with firsthand experience in radio astronomy science. Thus, remote radio astronomical observations allow students to learn with a first rate scientific equipment the basics of radio astronomy research, aiming to arouse scientific careers and positive attitudes toward science. In this contribution we show the current observational programs and some recent results.

Radio to gamma-ray variability study of blazar S5 0716+714

DOE PAGES

Rani, B.; Krichbaum, T. P.; Fuhrmann, L.; ...

2013-03-13

In this paper, we present the results of a series of radio, optical, X-ray, and γ-ray observations of the BL Lac object S50716+714 carried out between April 2007 and January 2011. The multifrequency observations were obtained using several ground- and space-based facilities. The intense optical monitoring of the source reveals faster repetitive variations superimposed on a long-term variability trend on a time scale of ~350 days. Episodes of fast variability recur on time scales of ~60-70 days. The intense and simultaneous activity at optical and γ-ray frequencies favors the synchrotron self-Compton mechanism for the production of the high-energy emission. Twomore » major low-peaking radio flares were observed during this high optical/γ-ray activity period. The radio flares are characterized by a rising and a decaying stage and agrees with the formation of a shock and its evolution. We found that the evolution of the radio flares requires a geometrical variation in addition to intrinsic variations of the source. Different estimates yield robust and self-consistent lower limits of δ ≥ 20 and equipartition magnetic field B eq ≥ 0.36 G. Causality arguments constrain the size of emission region θ ≤ 0.004 mas. We found a significant correlation between flux variations at radio frequencies with those at optical and γ-rays. Theoptical/GeV flux variations lead the radio variability by ~65 days. The longer time delays between low-peaking radio outbursts and optical flares imply that optical flares are the precursors of radio ones. An orphan X-ray flare challenges the simple, one-zone emission models, rendering them too simple. Finally, here we also describe the spectral energy distribution modeling of the source from simultaneous data taken through different activity periods.« less

Solar-geophysical data number 490, June 1985. Part 1: (Prompt reports). Data for May 1985, April 1985 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E. (Editor)

1985-01-01

Contents include: detailed index for 1984 to 1985; data for May 1985--(IUWDS alert periods (Advance and Worldwide) solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field); data for April 1985--(solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements by neutron monitor, geomagnetic indices, radio propagation indices); and late data--(geomagnetic indices, cosmic rays, calcium plage data).

FR II radio galaxies in the Sloan Digital Sky Survey: observational facts

NASA Astrophysics Data System (ADS)

Kozieł-Wierzbowska, D.; Stasińska, G.

2011-08-01

Starting from the Cambridge Catalogues of radio sources, we have created a sample of 401 Fanaroff-Riley type II (FR II) radio sources that have counterparts in the main galaxy sample of the seventh Data release of the Sloan Digital Sky Survey (SDSS) and analyse their radio and optical properties. We find that the luminosity in the Hα line - which we argue gives a better measure of the total emission-line flux than the widely used luminosity in [O III]- is strongly correlated with the radio luminosity P1.4 GHz. We show that the absence of emission lines in about one third of our sample is likely due to a detection threshold and not to a lack of optical activity. We also find a very strong correlation between the values of LHα and P1.4 GHz when scaled by ‘MBH’, an estimate of the black hole mass. We find that the properties of FR II galaxies are mainly driven by the Eddington parameter LHα/‘MBH’ or, equivalently, P1.4 GHz/‘MBH’. Radio galaxies with hotspots are found among the ones with the highest values of P1.4 GHz/‘MBH’. Compared to classical active galactic nuclei (AGN) hosts in the main galaxy sample of the SDSS, our FR II galaxies show a larger proportion of objects with very hard ionizing radiation field and large ionization parameter. A few objects are, on the contrary, ionized by a softer radiation field. Two of them have double-peaked emission lines and deserve more attention. We find that the black hole masses and stellar masses in FR II galaxies are very closely related: ‘MBH’∝M1.13* with very little scatter. A comparison sample of line-less galaxies in the SDSS follows exactly the same relation, although the masses are, on average, smaller. This suggests that the FR II radio phenomenon occurs in normal elliptical galaxies, preferentially in the most massive ones. Although most FR II galaxies are old, some contain traces of young stellar populations. Such young populations are not seen in normal line-less galaxies, suggesting that the radio (and optical) activity in some FR II galaxies may be triggered by recent star formation. The ‘MBH’-M* relation in a comparison sample of radio-quiet AGN hosts from the SDSS is very different, suggesting that galaxies which are still forming stars are also still building their central black holes. Globally, our study indicates that, while radio and optical activity are strongly related in FR II galaxies, the features of the optical activity in FR IIs are distinct from those of the bulk of radio-quiet active galaxies. An appendix (available as Supporting Information with the online version of the article) gives the radio maps of our FR II galaxies, superimposed on the SDSS images, and the parameters derived for our analysis that were not publicly available.

Radio stars observed in the LAMOST spectral survey

NASA Astrophysics Data System (ADS)

Zhang, Li-Yun; Yue, Qiang; Lu, Hong-Peng; Han, Xian-Ming L.; Zhang, Yong; Shi, Jian-Rong; Wang, Yue-Fei; Hou, Yong-Hui; Zi-Huang, Cao

2017-09-01

Radio stars have attracted astronomers’ attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 (DR2), published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5‧‧ and LAMOST objects classified as stars. We calculated the equivalent widths (EWs) of the Ca ii H&K, Hδ, Hγ, Hβ, Hα and Ca ii IRT lines by integrating the line profiles. Using the EWs of the Hα line, we detected 147 active stellar spectra of 89 objects having emissions above the Hα continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca ii IRT lines. The low value of the EW8542/EW8498 ratio for these 14 radio stars possibly alludes to chromospheric plage regions.

Solar-geophysical data number 479, July 1984. Part 1: (Prompt reports). Data for June 1984, May 1984 and later data

NASA Technical Reports Server (NTRS)

Coffey, H. E. (Editor)

1984-01-01

Solar and geophysical data for May and June 1984 are reported. Topics include: detailed index for 1983/1984; data for June 1984 (solar activity indices, solar flares, solar radio emission, mean solar magnetic field, boulder geomagnetic substorm log); data for May 1984 (solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements by neutron monitor, geomagnetic indices, radio propagation indices); and late data (geomagnetic indices March and April 1984 sudden commencements/solar flare effects, cosmic ray measurements by neutron monitor, and solar active regions).

FR0CAT: a FIRST catalog of FR 0 radio galaxies

NASA Astrophysics Data System (ADS)

Baldi, R. D.; Capetti, A.; Massaro, F.

2018-01-01

With the aim of exploring the properties of the class of FR 0 radio galaxies, we selected a sample of 108 compact radio sources, called FR0CAT, by combining observations from the NVSS, FIRST, and SDSS surveys. We included in the catalog sources with redshift ≤0.05, with a radio size ≲5 kpc, and with an optical spectrum characteristic of low-excitation galaxies. Their radio luminosities at 1.4 GHz are in the range 1038 ≲ νL1.4 ≲ 1040 erg s-1. The FR0CAT hosts are mostly (86%) luminous (-21 ≳ Mr ≳ -23) red early-type galaxies with black hole masses 108 ≲ MBH ≲ 109M⊙. These properties are similar to those seen for the hosts of FR I radio galaxies, but they are on average a factor 1.6 less massive. The number density of FR0CAT sources is 5 times higher than that of FR Is, and thus they represent the dominant population of radio sources in the local Universe. Different scenarios are considered to account for the smaller sizes and larger abundance of FR 0s with respect to FR Is. An age-size scenario that considers FR 0s as young radio galaxies that will all eventually evolve into extended radio sources cannot be reconciled with the large space density of FR 0s. However, the radio activity recurrence, with the duration of the active phase covering a wide range of values and with short active periods strongly favored with respect to longer ones, might account for their large density number. Alternatively, the jet properties of FR 0s might be intrinsically different from those of the FR Is, the former class having lower bulk Lorentz factors, possibly due to lower black hole spins. Our study indicates that FR 0s and FR I/IIs can be interpreted as two extremes of a continuous population of radio sources that is characterized by a broad distribution of sizes and luminosities of their extended radio emission, but shares a single class of host galaxies.

A Student's Hands-on Introduction to Radio Astronomy With the Simple Construction, Operation and Testing, Utilizing Commonly Available Materials, of a Functioning Solar Radio Telescope

NASA Astrophysics Data System (ADS)

Knight, D.

2016-12-01

Our study of the Sun, an object that provides life to this planet but also is a serious threat to the existence we now enjoy, is frequently limited in hands-on activities by the unavailability of the necessary observational tools. While small optical telescopes are more easily obtained, telescopes that work the other regions of the electromagnetic spectrum, such as the radio frequencies, are unusual. Radio emissions from solar storms, however, can be "viewed" by a student constructing a simple, tunable and inexpensive radio telescope designed to receive the most common radio frequencies broadcast from the Sun during such a storm. The apparatus employs normally available materials and technology in new purposes. Utilizing this telescope, students have the ability to test and modify its design for changes in frequency and signal amplitude, and therefore examine a wide spectrum of radio emission emanating from our star. This engaging introduction to radio electronics not only involves the study of the electrical circuit involved, but also sets the student up for detailed study in the form of specific research projects focusing on solar activity in the radio wavelengths. So far, my students have been actively involved in varying the electrical properties of a simple one-transistor circuit that selects the observational frequencies of the solar radio telescope they have constructed. Student research projects also have examined antenna design in terms of directionality and signal strength gain. In the future, collaboration is possible to link student observers in different locations on this planet, allowing for significant peer evaluation and cooperation. NASA's "Project Jove", a program that Sonoma Valley High School and Robert Ferguson Observatory have been connected with since about the year 2000, already has a worldwide collaboration network in place for similar student-operated radio telescopes for primarily studying Jupiter. Because of the higher frequencies with most of the solar storm radio spectrum, our apparatus is correspondingly much smaller and easier to manipulate, thus promoting student research on a much larger scale.

50 CFR 300.37 - Radio monitoring.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Radio monitoring. 300.37 Section 300.37 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.37 Radio monitoring. The international distress frequency, 2.182 mHz...

50 CFR 300.37 - Radio monitoring.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 11 2012-10-01 2012-10-01 false Radio monitoring. 300.37 Section 300.37 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.37 Radio monitoring. The international distress frequency, 2.182 mHz...

50 CFR 300.37 - Radio monitoring.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Radio monitoring. 300.37 Section 300.37 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.37 Radio monitoring. The international distress frequency, 2.182 mHz...

50 CFR 300.37 - Radio monitoring.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 11 2014-10-01 2014-10-01 false Radio monitoring. 300.37 Section 300.37 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.37 Radio monitoring. The international distress frequency, 2.182 mHz...

50 CFR 300.37 - Radio monitoring.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Radio monitoring. 300.37 Section 300.37 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.37 Radio monitoring. The international distress frequency, 2.182 mHz...

Variability of fractal dimension of solar radio flux

NASA Astrophysics Data System (ADS)

Bhatt, Hitaishi; Sharma, Som Kumar; Trivedi, Rupal; Vats, Hari Om

2018-04-01

In the present communication, the variation of the fractal dimension of solar radio flux is reported. Solar radio flux observations on a day to day basis at 410, 1415, 2695, 4995, and 8800 MHz are used in this study. The data were recorded at Learmonth Solar Observatory, Australia from 1988 to 2009 covering an epoch of two solar activity cycles (22 yr). The fractal dimension is calculated for the listed frequencies for this period. The fractal dimension, being a measure of randomness, represents variability of solar radio flux at shorter time-scales. The contour plot of fractal dimension on a grid of years versus radio frequency suggests high correlation with solar activity. Fractal dimension increases with increasing frequency suggests randomness increases towards the inner corona. This study also shows that the low frequency is more affected by solar activity (at low frequency fractal dimension difference between solar maximum and solar minimum is 0.42) whereas, the higher frequency is less affected by solar activity (here fractal dimension difference between solar maximum and solar minimum is 0.07). A good positive correlation is found between fractal dimension averaged over all frequencies and yearly averaged sunspot number (Pearson's coefficient is 0.87).

STEREO/Waves Education and Public Outreach

NASA Astrophysics Data System (ADS)

MacDowall, R. J.; Bougeret, J.; Bale, S. D.; Goetz, K.; Kaiser, M. L.

2005-05-01

We present the education and public outreach plan and activities of the STEREO Waves (aka SWAVES) investigation. SWAVES measures radio emissions from the solar corona, interplanetary medium, and terrestrial magnetosphere, as well as in situ waves in the solar wind. In addition to the web site components that display stereo/multi-spacecraft data in a graphical form and explain the science and instruments, we will focus on the following three areas of EPO: class-room demonstrations using models of the STEREO spacecraft with battery powered radio receivers (and speakers) to illustrate spacecraft radio direction finding, teacher developed and tested class-room activities using SWAVES solar radio observations to motivate geometry and trigonometry, and sound-based delivery of characteristic radio and plasma wave events from the SWAVES web site for accessibility and esthetic reasons. Examples of each element will be demonstrated.

`Zwicky's Nonet': a compact merging ensemble of nine galaxies and 4C 35.06, a peculiar radio galaxy with dancing radio jets

NASA Astrophysics Data System (ADS)

Biju, K. G.; Bagchi, Joydeep; Ishwara-Chandra, C. H.; Pandey-Pommier, M.; Jacob, Joe; Patil, M. K.; Kumar, P. Sunil; Pandge, Mahadev; Dabhade, Pratik; Gaikwad, Madhuri; Dhurde, Samir; Abraham, Sheelu; Vivek, M.; Mahabal, Ashish A.; Djorgovski, S. G.

2017-10-01

We report the results of our radio, optical and infrared studies of a peculiar radio source 4C 35.06, an extended radio-loud active galactic nucleus (AGN) at the centre of galaxy cluster Abell 407 (z = 0.047). The central region of this cluster hosts a remarkably tight ensemble of nine galaxies, the spectra of which resemble those of passive red ellipticals, embedded within a diffuse stellar halo of ˜1 arcmin size. This system (named 'Zwicky's Nonet') provides unique and compelling evidence for a multiple-nucleus cD galaxy precursor. Multifrequency radio observations of 4C 35.06 with the Giant Meterwave Radio Telescope (GMRT) at 610, 235 and 150 MHz reveal a system of 400-kpc scale helically twisted and kinked radio jets and outer diffuse lobes. The outer extremities of jets contain extremely steep-spectrum (spectral index -1.7 to -2.5) relic/fossil radio plasma with a spectral age of a few ×(107-108) yr. Such ultra-steep spectrum relic radio lobes without definitive hotspots are rare and they provide an opportunity to understand the life cycle of relativistic jets and physics of black hole mergers in dense environments. We interpret our observations of this radio source in the context of growth of its central black hole, triggering of its AGN activity and jet precession, all possibly caused by galaxy mergers in this dense galactic system. A slow conical precession of the jet axis due to gravitational perturbation between interacting black holes is invoked to explain the unusual jet morphology.

A Radio Astronomy Curriculum for STARLAB

NASA Astrophysics Data System (ADS)

Boltuch, D.; Hund, L.; Buck, S.; Fultz, C.; Smith, T.; Harris, R.; Castelaz, M. W.; Moffett, D.; LaFratta, M.; Walsh, L.

2005-12-01

We present elements of a curriculum that will accompany the STARLAB module "Sensing the Radio Sky" a portable planetarium program and projection of the radio sky. The curriculum will serve to familiarize high school students to a set of topics in radio astronomy. The curriculum includes lessons and activities addressing several topics related to radio astronomy and the Milky Way that consists of two main resources: a manual and a multimedia website. It is designed to accommodate a wide variety of possible uses and time constraints. The manufacturer of STARLAB, Learning Technologies, Inc. produces a short manual to accompany each presentation for the STARLAB. The "Sensing the Radio Sky" manual we have created includes the mandatory, minimum background information that students need to understand radio astronomy. It briefly discusses waves and electromagnetic radiation, similarities and differences between optical and radio astronomy, probable misconceptions about radio astronomy, how radio images are produced, synchrotron radiation in the Milky Way, and galactic coordinates. It also includes a script that presenters can choose to follow inside the STARLAB, a lesson plan for teachers, and activities for students to complete before and after the STARLAB experience that mirror the scientific method. The multimedia website includes more detailed information about electromagnetic radiation and a more detailed comparison of optical and radio astronomy. It also discusses the life cycles of stars, radiation from a variety of specific sources, and pulsars, as each relates to radio astronomy. The five highly detailed lessons are pulled together in sixth "overview lesson", intended for use by teachers who want to present more than the basic material in the manual, but do not have the classroom time to teach all five of the in-depth lessons. . We acknowledge support from the NSF Internship in Public Science Education Program grant number 0324729.

Remnant radio-loud AGN in the Herschel-ATLAS field

NASA Astrophysics Data System (ADS)

Mahatma, V. H.; Hardcastle, M. J.; Williams, W. L.; Brienza, M.; Brüggen, M.; Croston, J. H.; Gurkan, G.; Harwood, J. J.; Kunert-Bajraszewska, M.; Morganti, R.; Röttgering, H. J. A.; Shimwell, T. W.; Tasse, C.

2018-04-01

Only a small fraction of observed active galactic nuclei (AGN) display large-scale radio emission associated with jets, yet these radio-loud AGN have become increasingly important in models of galaxy evolution. In determining the dynamics and energetics of the radio sources over cosmic time, a key question concerns what happens when their jets switch off. The resulting `remnant' radio-loud AGN have been surprisingly evasive in past radio surveys, and therefore statistical information on the population of radio-loud AGN in their dying phase is limited. In this paper, with the recent developments of Low-Frequency Array (LOFAR) and the Very Large Array, we are able to provide a systematically selected sample of remnant radio-loud AGN in the Herschel-ATLAS field. Using a simple core-detection method, we constrain the upper limit on the fraction of remnants in our radio-loud AGN sample to 9 per cent, implying that the extended lobe emission fades rapidly once the core/jets turn off. We also find that our remnant sample has a wide range of spectral indices (-1.5≤slant α ^{1400}_{150}≤slant -0.5), confirming that the lobes of some remnants may possess flat spectra at low frequencies just as active sources do. We suggest that, even with the unprecedented sensitivity of LOFAR, our sample may still only contain the youngest of the remnant population.

Control of active reflector system for radio telescope

NASA Astrophysics Data System (ADS)

Zhou, Guo-hua; Li, Guo-ping; Zhang, Yong; Zhang, Zhen-chao

2016-10-01

According to the control requirements of the active reflector surface in the 110 m radio telescope at QiTai(QTT) Xinjiang, a new displacement actuator and a new displacement control system were designed and manufactured and then their characteristics were tested by a dual-frequency laser interferometer in the micro-displacement laboratory. The displacement actuator was designed by a scheme of high precision worm and roller screw structures, and the displacement control system was based on a ARM micro-processor. Finally, the S curve acceleration control methods were used to design the hardware platform and software algorithm for the active reflection surface of the control system. The test experiments were performed based on the laser metrology system on an active reflector close-loop antenna prototype for large radio telescope. Experimental results indicate that it achieves a 30 mm working stroke and 5 μm RMS motion resolution. The accuracy (standard deviation) is 3.67 mm, and the error between the determined and theoretical values is 0.04% when the rated load is 300 kg, the step is 2 mm and the stroke is 30mm. Furthermore, the active reflector integrated system was tested by the laser sensors with the accuracy of 0.25 μm RMS on 4-panel radio telescope prototype, the measurement results show that the integrated precision of the active reflector closed-loop control system is less than 5 μm RMS, and well satisfies the technical requirements of active reflector control system of the QTT radio telescope in 3 mm wavelength.

X-ray study of a sample of FR0 radio galaxies: unveiling the nature of the central engine

NASA Astrophysics Data System (ADS)

Torresi, E.; Grandi, P.; Capetti, A.; Baldi, R. D.; Giovannini, G.

2018-06-01

Fanaroff-Riley type 0 radio galaxies (FR0s) are compact radio sources that represent the bulk of the radio-loud active galactic nuclei (AGN) population, but they are still poorly understood. Pilot studies on these sources have been already performed at radio and optical wavelengths: here we present the first X-ray study of a sample of 19 FR0 radio galaxies selected from the Sloan Digital Sky Survey/NRAO VLA Sky Survey/Faint Images of the Radio Sky at Twenty-cm sample of Best & Heckman, with redshift ≤0.15, radio size ≤10 kpc, and optically classified as low-excitation galaxies. The X-ray spectra are modelled with a power-law component absorbed by Galactic column density with, in some cases, a contribution from thermal extended gas. The X-ray photons are likely produced by the jet as attested by the observed correlation between X-ray (2-10 keV) and radio (5 GHz) luminosities, similar to Fanaroff-Riley type I radio galaxies (FRIs). The estimated Eddington-scaled luminosities indicate a low accretion rate. Overall, we find that the X-ray properties of FR0s are indistinguishable from those of FRIs, thus adding another similarity between AGN associated with compact and extended radio sources. A comparison between FR0s and low-luminosity BL Lacs rules out important beaming effects in the X-ray emission of the compact radio galaxies. FR0s have different X-ray properties with respect to young radio sources (e.g. gigahertz-peaked spectrum/compact steep spectrum sources), generally characterized by higher X-ray luminosities and more complex spectra. In conclusion, the paucity of extended radio emission in FR0s is probably related to the intrinsic properties of their jets that prevent the formation of extended structures, and/or to intermittent activity of their engines.

Empirical Calibration of Small Explosion Seismic And Acoustic Phenomenology in New England

DTIC Science & Technology

2008-10-31

site was too close to a nearby cell /radio tower and the active quarry wall to detonate our planned 400 lb explosions. Core drilling at an...alternative test site (Figure 52) was conducted further away from the active quarry wall and a nearby cell /radio tower. The alternative site would be far...experiment was returned into the original location (Figure 52). In order to reduce the projected ground vibrations at the cell /radio tower and high

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1991-01-01

This quarterly publication provides archival reports on developments in programs managed by the Jet Propulsion Laboratory's (JPL's) Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on the activities of the Deep Space Network (DSN) in planning, in supporting research and technology, in implementation, and in operations. Also included is standards activity at JPL for space data, information systems, and reimbursable DSN work performed for other space agencies through NASA.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1990-01-01

Archival reports on developments in programs managed by the Jet Propulsion Laboratory's (JPL) Office of Telecommunications and Data Acquisition (TDA) are given. Space communications, radio navigation, radio science, and ground-based radio and radar astronomy, activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, supporting research and technology, implementation, and operations are reported. Also included is TDA-funded activity at JPL on data and information systems and reimbursable Deep Space Network (DSN) work performed for other space agencies through NASA.

The Telecommunications and Data Acquisition

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1992-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC).

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

NASA Astrophysics Data System (ADS)

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.

EVIDENCE FOR INFRARED-FAINT RADIO SOURCES AS z > 1 RADIO-LOUD ACTIVE GALACTIC NUCLEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2010-02-10

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 {mu}m) 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 {approx}> 1) active galactic nuclei.

First direct comparison of high and low ionization line kinematics in active galactic nuclei

NASA Technical Reports Server (NTRS)

Sulentic, J. W.; Marziani, P.; Dultzin-Hacyan, D.; Calvani, M.; Moles, M.

1995-01-01

We present first results of a comparison of emission line shift properties for the high (HILs) and low (LILs) ionization lines in 43 low-reshift quasars. We identify a core sample of C IV lambda 1549 and hydrogen beta profiles with a wide distribution of red- and blueshifts (less than or equal to +/- 1000 km/sec). We also identify two tails in this distribution: one with large hydrogen beta redshifts (greater than or equal to 2000 km/sec) and another with large C IV blueshifts (greater than or equal to 1500 km/sec). The tails are mutually exclusive. All objects with extreme hydrogen beta redshift are radio loud, and all objects with extreme C IV blueshift are radio quiet. The core samples of smaller shifts can be most simply divided into: (1) hydrogen beta - a redshifted radio-loud population (related to the tail) and a radio-quiet population with mean shift near zero, and (2) C IV - a blueshifted radio-quiet population (related to the tail) and a radio-loud population with mean shift near zero. The results suggest fundamentally different kinematics for the HILs and LILs. They also suggest very different kinematics for radio-loud and radio-quiet active galactic nuclei. They also favor a predominance of radial motion in a large fraction of the sample.

The difference between radio-loud and radio-quiet active galaxies

NASA Astrophysics Data System (ADS)

Wilson, A. S.; Colbert, E. J. M.

1995-01-01

The recent development of unified theories of active galactic nuclei (AGNs) has indicated that there are two physically distinct classes of these objects--radio-loud and radio-quiet. Despite differences, the (probable) thermal emissions from the AGNs (continua and lines from X-ray to infrared wavelengths) are quite similar to the two classes of object. We argue that this last result suggests that the black hole masses and mass accretion rates in the two classes are not greatly different, and that the difference between the classes is associated with the spin of the black hole. We assume that the normal process of accretion through a disk does not lead to rapidly spinning holes and propose that galaxies (e.g., spirals) which have not suffered a recent major merger event contain nonrotating or only slowly rotating black holes. When two such galaxies merge, the two black holes are known to form a binary and we assume that they eventually coalesce. The ratio of the number of radio-loud to radio-quiet AGNs at a given thermal (e.g., optical) luminosity is determined by the galaxy merger rate. Comparisons between the predicted and observed radio luminosity functions constrain the efficiencies with which jet power is extracted from the spinning hole and radio emission is produced by the jet.

EUV and Magnetic Activities Associated with Type-I Solar Radio Bursts

NASA Astrophysics Data System (ADS)

Li, C. Y.; Chen, Y.; Wang, B.; Ruan, G. P.; Feng, S. W.; Du, G. H.; Kong, X. L.

2017-06-01

Type-I bursts ( i.e. noise storms) are the earliest-known type of solar radio emission at the meter wavelength. They are believed to be excited by non-thermal energetic electrons accelerated in the corona. The underlying dynamic process and exact emission mechanism still remain unresolved. Here, with a combined analysis of extreme ultraviolet (EUV), radio and photospheric magnetic field data of unprecedented quality recorded during a type-I storm on 30 July 2011, we identify a good correlation between the radio bursts and the co-spatial EUV and magnetic activities. The EUV activities manifest themselves as three major brightening stripes above a region adjacent to a compact sunspot, while the magnetic field there presents multiple moving magnetic features (MMFs) with persistent coalescence or cancelation and a morphologically similar three-part distribution. We find that the type-I intensities are correlated with those of the EUV emissions at various wavelengths with a correlation coefficient of 0.7 - 0.8. In addition, in the region between the brightening EUV stripes and the radio sources there appear consistent dynamic motions with a series of bi-directional flows, suggesting ongoing small-scale reconnection there. Mainly based on the induced connection between the magnetic motion at the photosphere and the EUV and radio activities in the corona, we suggest that the observed type-I noise storms and the EUV brightening activities are the consequence of small-scale magnetic reconnection driven by MMFs. This is in support of the original proposal made by Bentley et al. ( Solar Phys. 193, 227, 2000).

Analysis and Modeling of Jovian Radio Emissions Observed by Galileo

NASA Technical Reports Server (NTRS)

Menietti, J. D.

2003-01-01

Our studies of Jovian radio emission have resulted in the publication of five papers in refereed journals, with three additional papers in progress. The topics of these papers include the study of narrow-band kilometric radio emission; the apparent control of radio emission by Callisto; quasi-periodic radio emission; hectometric attenuation lanes and their relationship to Io volcanic activity; and modeling of HOM attenuation lanes using ray tracing. A further study of the control of radio emission by Jovian satellites is currently in progress. Abstracts of each of these papers are contained in the Appendix. A list of the publication titles are also included.

Sampling strategies for radio-tracking coyotes

USGS Publications Warehouse

Smith, G.J.; Cary, J.R.; Rongstad, O.J.

1981-01-01

Ten coyotes radio-tracked for 24 h periods were most active at night and moved little during daylight hours. Home-range size determined from radio-locations of 3 adult coyotes increased with the number of locations until an asymptote was reached at about 35-40 independent day locations or 3 6 nights of hourly radio-locations. Activity of the coyote did not affect the asymptotic nature of the home-range calculations, but home-range sizes determined from more than 3 nights of hourly locations were considerably larger than home-range sizes determined from daylight locations. Coyote home-range sizes were calculated from daylight locations, full-night tracking periods, and half-night tracking periods. Full- and half-lnight sampling strategies involved obtaining hourly radio-locations during 12 and 6 h periods, respectively. The half-night sampling strategy was the best compromise for our needs, as it adequately indexed the home-range size, reduced time and energy spent, and standardized the area calculation without requiring the researcher to become completely nocturnal. Sight tracking also provided information about coyote activity and sociability.

ON THE BRIGHTNESS AND WAITING-TIME DISTRIBUTIONS OF A TYPE III RADIO STORM OBSERVED BY STEREO/WAVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eastwood, J. P.; Hudson, H. S.; Krucker, S.

2010-01-10

Type III solar radio storms, observed at frequencies below {approx}16 MHz by space-borne radio experiments, correspond to the quasi-continuous, bursty emission of electron beams onto open field lines above active regions. The mechanisms by which a storm can persist in some cases for more than a solar rotation whilst exhibiting considerable radio activity are poorly understood. To address this issue, the statistical properties of a type III storm observed by the STEREO/WAVES radio experiment are presented, examining both the brightness distribution and (for the first time) the waiting-time distribution (WTD). Single power-law behavior is observed in the number distribution asmore » a function of brightness; the power-law index is {approx}2.1 and is largely independent of frequency. The WTD is found to be consistent with a piecewise-constant Poisson process. This indicates that during the storm individual type III bursts occur independently and suggests that the storm dynamics are consistent with avalanche-type behavior in the underlying active region.« less

Children's Stories through the Air: Librarian-Broadcasters, 1922-1941

ERIC Educational Resources Information Center

Welch, Cindy C.

2012-01-01

Children's librarians were active radio broadcasters as early as 1922, when American commercial radio was just beginning. As they utilized the new technology of radio to promote reading, literature and outreach, they transferred techniques and materials already familiar from their work in neighborhood libraries. This article documents children's…

Preference and Utilities for Prostate Cancer Screening and Treatment: Assessment of the Underlying Decision Making Process

DTIC Science & Technology

2005-01-01

Watkins-Bruner, Deborah radio advertisements was overwhelming! In between radio ads we continued to recruit through outreach activities and advertising ...in local newspapers. E. Conclusions: Radio advertisement has proved to be a very effective media for recruitment of our control sample. F. References

Ain't no Crab, PWN Got a Brand New Bag: Correlated Radio and X-ray Structures in Pulsar Wind Nebulae

NASA Astrophysics Data System (ADS)

Roberts, M. S. E.; Lyutikov, M.; Gaensler, B. M.; Brogan, C. L.; Tam, C. R.; Romani, R. W.

2005-04-01

The traditional view of radio pulsar wind nebulae (PWN), encouraged by the Crab nebula's X-ray and radio morphologies, is that they are a result of the integrated history of their pulsars' wind. The radio emission should therefore be largely unaffected by recent pulsar activity, and hence minimally correlated with structures in the X-ray nebulae. Observations of several PWN, both stationary and rapidly moving, now show clear morphological relationships between structures in the radio and X-ray with radio intensity variations on the order of unity. We present high-resolution X-ray and radio images of several PWN of both types and discuss the morphological relationships between the two wavebands.

Large-Scale Outflows in Seyfert Galaxies

NASA Astrophysics Data System (ADS)

Colbert, E. J. M.; Baum, S. A.

1995-12-01

\\catcode`\\@=11 \\ialign{m @th#1hfil ##hfil \\crcr#2\\crcr\\sim\\crcr}}} \\catcode`\\@=12 Highly collimated outflows extend out to Mpc scales in many radio-loud active galaxies. In Seyfert galaxies, which are radio-quiet, the outflows extend out to kpc scales and do not appear to be as highly collimated. In order to study the nature of large-scale (>~1 kpc) outflows in Seyferts, we have conducted optical, radio and X-ray surveys of a distance-limited sample of 22 edge-on Seyfert galaxies. Results of the optical emission-line imaging and spectroscopic survey imply that large-scale outflows are present in >~{{1} /{4}} of all Seyferts. The radio (VLA) and X-ray (ROSAT) surveys show that large-scale radio and X-ray emission is present at about the same frequency. Kinetic luminosities of the outflows in Seyferts are comparable to those in starburst-driven superwinds. Large-scale radio sources in Seyferts appear diffuse, but do not resemble radio halos found in some edge-on starburst galaxies (e.g. M82). We discuss the feasibility of the outflows being powered by the active nucleus (e.g. a jet) or a circumnuclear starburst.

EVA Radio DRATS 2011 Report

NASA Technical Reports Server (NTRS)

Swank, Aaron J.; Bakula, Casey J.

2012-01-01

In the Fall of 2011, National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) participated in the Desert Research and Technology Studies (DRATS) field experiments held near Flagstaff, Arizona. The objective of the DRATS outing is to provide analog mission testing of candidate technologies for space exploration, especially those technologies applicable to human exploration of extra- terrestrial rocky bodies. These activities are performed at locations with similarities to extra-terrestrial conditions. This report describes the Extravehicular Activity (EVA) Dual-Band Radio Communication System which was demonstrated during the 2011 outing. The EVA radio system is designed to transport both voice and telemetry data through a mobile ad hoc wireless network and employs a dual-band radio configuration. Some key characteristics of this system include: 1. Dual-band radio configuration. 2. Intelligent switching between two different capability wireless networks. 3. Self-healing network. 4. Simultaneous data and voice communication.

Radio AGN in the local universe: unification, triggering and evolution

NASA Astrophysics Data System (ADS)

Tadhunter, Clive

2016-06-01

Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (L_{1.4 GHz} > 10^{24} W Hz^{-1}) are a key sub-class of the overall AGN population. Recently their study has benefitted dramatically from the availability of high-quality data covering the X-ray to far-IR wavelength range obtained with the current generation of ground- and space-based telescope facilities. Reflecting this progress, here I review our current state of understanding of the population of radio AGN at low and intermediate redshifts (z < 0.7), concentrating on their nuclear AGN and host galaxy properties, and covering three interlocking themes: the classification of radio AGN and its interpretation; the triggering and fuelling of the jet and AGN activity; and the evolution of the host galaxies. I show that much of the observed diversity in the AGN properties of radio AGN can be explained in terms of a combination of orientation/anisotropy, mass accretion rate, and variability effects. The detailed morphologies of the host galaxies are consistent with the triggering of strong-line radio galaxies (SLRG) in galaxy mergers. However, the star formation properties and cool ISM contents suggest that the triggering mergers are relatively minor in terms of their gas masses in most cases, and would not lead to major growth of the supermassive black holes and stellar bulges; therefore, apart from a minority (<20 %) that show evidence for higher star formation rates and more massive cool ISM reservoirs, the SLRG represent late-time re-triggering of activity in mature giant elliptical galaxies. In contrast, the host and environmental properties of weak-line radio galaxies (WLRG) with Fanaroff-Riley class I radio morphologies are consistent with more gradual fuelling of the activity via gas accretion at low rates onto the supermassive black holes.

On the unity of activity in galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowan-Robinson, M.

1977-05-01

A scheme is presented which unites quasars, radio galaxies, N galaxies, and Seyfert galaxies into a single picture of activity in galaxies. Probability functions are given for optical and radio cores, and extended radio sources (in the case of ellipticals), for both spirals and ellipticals. Activity occurs in galaxies of all luminosities, but the strength of it is made proportional to galaxy luminosity. It is assumed that there is dust surrounding the optical cores, to explain the strong infrared emission in Seyferts.Quasars may, in this picture, occur in both spirals and ellipticals, and in fact most optically selected QSOs aremore » predicted to be in spirals.« less

Exploring the multiband emission of TXS 0536+145: the most distant -γray flaring blazar

DOE PAGES

Orienti, M.; D'Ammando, F.; Giroletti, M.; ...

2014-09-15

We report results of a multi-band monitoring campaign of the flat spectrum radio quasar TXS 0536+145 at redshift 2.69. This source was detected during a very high γ-ray activity state in 2012 March by the Large Area Telescope on board Fermi, becoming the γ-ray flaring blazar at the highest redshift detected so far. At the peak of the flare the source reached an apparent isotropic γ-ray luminosity of 6.6×1049 erg s-1 which is comparable to the values achieved by the most luminous blazars. This activity triggered radio-to-X-rays monitoring observations by Swift, Very Long Baseline Array, European VLBI Network, and Medicinamore » single-dish telescope. Significant variability was observed from radio to X-rays supporting the identification of the γ-ray source with TXS 0536+145. Both the radio and γ-ray light curves show a similar behaviour, with the γ-rays leading the radio variability with a time lag of about 4-6 months. The luminosity increase is associated with a flattening of the radio spectrum. No new superluminal component associated with the flare was detected in high resolution parsec-scale radio images. During the flare the γ-ray spectrum seems to deviate from a power law, showing a curvature that was not present during the average activity state. The γ-ray properties of TXS 0536+145 are consistent with those shown by the high-redshift γ-ray blazar population.« less

Exploring the multiband emission of TXS 0536+145: the most distant γ-ray flaring blazar

NASA Astrophysics Data System (ADS)

Orienti, M.; D'Ammando, F.; Giroletti, M.; Finke, J.; Ajello, M.; Dallacasa, D.; Venturi, T.

2014-11-01

We report results of a multiband monitoring campaign of the flat spectrum radio quasar TXS 0536+145 at redshift 2.69. This source was detected during a very high γ-ray activity state in 2012 March by the Large Area Telescope on board Fermi, becoming the γ-ray flaring blazar at the highest redshift detected so far. At the peak of the flare the source reached an apparent isotropic γ-ray luminosity of 6.6 × 1049 erg s-1 which is comparable to the values achieved by the most luminous blazars. This activity triggered radio-to-X-rays monitoring observations by Swift, Very Long Baseline Array, European VLBI Network, and Medicina single-dish telescope. Significant variability was observed from radio to X-rays supporting the identification of the γ-ray source with TXS 0536+145. Both the radio and γ-ray light curves show a similar behaviour, with the γ-rays leading the radio variability with a time lag of about 4-6 months. The luminosity increase is associated with a flattening of the radio spectrum. No new superluminal component associated with the flare was detected in high-resolution parsec-scale radio images. During the flare the γ-ray spectrum seems to deviate from a power law, showing a curvature that was not present during the average activity state. The γ-ray properties of TXS 0536+145 are consistent with those shown by the high-redshift γ-ray blazar population.

The Jet-driven Outflow in the Radio Galaxy SDSS J1517+3353: Implications for Double-peaked Narrow-line Active Galactic Nucleus

NASA Astrophysics Data System (ADS)

Rosario, D. J.; Shields, G. A.; Taylor, G. B.; Salviander, S.; Smith, K. L.

2010-06-01

We report on the study of an intriguing active galaxy that was selected as a potential multiple supermassive black hole merger in the early-type host SDSS J151709.20+335324.7 (z = 0.135) from a complete search for double-peaked [O III] lines from the SDSS spectroscopic quasi-stellar object (QSO) database. Ground-based SDSS imaging reveals two blue structures on either side of the photometric center of the host galaxy, separated from each other by about 5.7 kpc. From a combination of SDSS fiber and Keck/HIRES long-slit spectroscopy, it is demonstrated that, in addition to these two features, a third distinct structure surrounds the nucleus of the host galaxy. All three structures exhibit highly ionized line emission with line ratios characteristic of Seyfert II active galactic nuclei. The analysis of spatially resolved emission-line profiles from the HIRES spectrum reveal three distinct kinematic subcomponents, one at rest and the other two moving at -350 km s-1 and 500 km s-1 with respect to the systemic velocity of the host galaxy. A comparison of imaging and spectral data confirm a strong association between the kinematic components and the spatial knots, which implies a highly disturbed and complex active region in this object. A comparative analysis of the broadband positions, colors, kinematics, and spectral properties of the knots in this system lead to two plausible explanations: (1) a multiple active galactic nucleus (AGN) produced due to a massive dry merger, or (2) a very powerful radio jet-driven outflow. Subsequent VLA radio imaging reveals a clear jet aligned with the emission-line gas, confirming the latter explanation. We use the broadband radio measurements to examine the impact of the jet on the interstellar medium of the host galaxy, and find that the energy in the radio lobes can heat a significant fraction of the gas to the virial temperature. Finally, we discuss tests that may help future surveys distinguish between jet-driven kinematics and true black-hole binaries. J1517+3353 is a remarkable laboratory for AGN feedback and warrants deeper follow-up study. In the Appendix, we present high-resolution radio imaging of a second AGN with double-peaked [O III] lines, SDSS J112939.78+605742.6, which shows a sub-arcsecond radio jet. If the double-peaked nature of the narrow lines in radio-loud AGNs are generally due to radio jet interactions, we suggest that extended radio structure should be expected in most of such systems.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1983-01-01

Developments in programs in telecommunication and data acquisition in space communications, radio navigation, radio science, and ground based radio astronomy are reported. Activities of the deep space network (DSN) and its associated ground communication facility (GCF) in planning, supporting research and technology, implementation, and in operations are outlined. The publication of reports on the application of radio interferometry at microwave frequencies for geodynamic measurements are presented. Implementation and operation for searching the microwave spectrum is reported.

LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift

NASA Astrophysics Data System (ADS)

Brienza, M.; Godfrey, L.; Morganti, R.; Vilchez, N.; Maddox, N.; Murgia, M.; Orru, E.; Shulevski, A.; Best, P. N.; Brüggen, M.; Harwood, J. J.; Jamrozy, M.; Jarvis, M. J.; Mahony, E. K.; McKean, J.; Röttgering, H. J. A.

2016-01-01

Context. Remnant radio galaxies represent the final dying phase of radio galaxy evolution in which the jets are no longer active. Remnants are rare in flux-limited samples, comprising at most a few percent. As a result of their rarity and because they are difficult to identify, this dying phase remains poorly understood and the luminosity evolution is largely unconstrained. Aims: Here we present the discovery and detailed analysis of a large (700 kpc) remnant radio galaxy with a low surface brightness that has been identified in LOFAR images at 150 MHz. Methods: By combining LOFAR data with new follow-up Westerbork observations and archival data at higher frequencies, we investigated the source morphology and spectral properties from 116 to 4850 MHz. By modelling the radio spectrum, we probed characteristic timescales of the radio activity. Results: The source has a relatively smooth, diffuse, amorphous appearance together with a very weak central compact core that is associated with the host galaxy located at z = 0.051. From our ageing and morphological analysis it is clear that the nuclear engine is currently switched off or, at most, active at a very low power state. We find that the source has remained visible in the remnant phase for about 60 Myr, significantly longer than its active phase of 15 Myr, despite being located outside a cluster. The host galaxy is currently interacting with another galaxy located at a projected separation of 15 kpc and a radial velocity offset of ~ 300 km s-1. This interaction may have played a role in the triggering and/or shut-down of the radio jets. Conclusions: The spectral shape of this remnant radio galaxy differs from most of the previously identified remnant sources, which show steep or curved spectra at low to intermediate frequencies. Our results demonstrate that remnant radio galaxies can show a wide range of evolutionary paths and spectral properties. In light of this finding and in preparation for new-generation deep low-frequency surveys, we discuss the selection criteria to be used to select representative samples of these sources.

Star-formation in the central kpc of the starburst/LINER galaxy NGC 1614

NASA Astrophysics Data System (ADS)

Olsson, E.; Aalto, S.; Thomasson, M.; Beswick, R.

2010-04-01

Aims: The aim is to investigate the star-formation and LINER (low ionization nuclear emission line region) activity within the central kiloparsec of the galaxy NGC 1614. In this paper the radio continuum morphology, which provides a tracer of both nuclear and star-formation activity, and the distribution and dynamics of the cold molecular and atomic gas feeding this activity, are studied. In particular, the nature of an R ≈ 300 pc nuclear ring of star-formation and its relationship to the LINER activity in NGC 1614 is addressed. Methods: A high angular resolution, multi-wavelength study of the LINER galaxy NGC 1614 has been performed. Deep observations of the CO 1-0 spectral line were performed using the Owens Valley Radio Observatory (OVRO). These data have been complemented by extensive multi-frequency radio continuum and Hi absorption observations using the Very Large Array (VLA) and Multi-Element Radio Linked Interferometer Network (MERLIN). Results: Toward the center of NGC 1614, we have detected a ring of radio continuum emission with a radius of 300 pc. This ring is coincident with previous radio and Paα observations. The dynamical mass of the ring based on Hi absorption is 3.1 × 109 M⊙. The peak of the integrated CO 1-0 emission is shifted by 1” to the north-west of the ring center. An upper limit to the molecular gas mass in the ring region is ~1.7 × 109 M⊙. Inside the ring, there is a north to south elongated 1.4 GHz radio continuum feature, with a nuclear peak. This peak is also seen in the 5 GHz radio continuum and in the CO. Conclusions: We suggest that the R = 300 pc star forming ring represents the radius of a dynamical resonance - as an alternative to the scenario that the starburst is propagating outwards from the center into a molecular ring. The ring-like appearance is probably part of a spiral structure. Substantial amounts of molecular gas have passed the radius of the ring and reached the nuclear region. The nuclear peak seen in 5 GHz radio continuum and CO is likely related to previous star formation, where all molecular gas was not consumed. The LINER-like optical spectrum observed in NGC 1614 may be due to nuclear starburst activity, and not to an active galactic nucleus (AGN). Although the presence of an AGN cannot be excluded.

Fermi Large Area Telescope Observations Of Misaligned Active Galactic Nuclei

DOE PAGES

Abdo, A. A.

2010-08-13

Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a γ-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sourcesmore » associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The γ-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the γ-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the γ-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the γ-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.« less

Discovery of Misaligned Radio Emission in Galaxy Cluster Zw CL 2971

NASA Astrophysics Data System (ADS)

Wallack, Nicole; Migliore, C.; Resnick, A.; White, T.; Liu, C.

2014-01-01

In a search for green valley galaxies with radio loud active galactic nuclei (AGN), we found one such object that may be associated with the cluster of galaxies Zw CL 2971 (z = 0.098). Serendipitously, we found in this cluster a strong bent-jet radio source associated with the cluster's central dominant (cD) elliptical galaxy. The center of the cD galaxy is coincident (0.35 arcsecond) with the second brightest spot of radio continuum emission (34.3 mJy as measured by FIRST), but the brightest radio hotspot (66.8 mJy) is offset by 4.6 arcseconds 9 kpc at the redshift of the cluster) and has no visible counterpart. Furthermore, the optical spectrum of the cD galaxy has only weak emission lines, suggesting the absence of a currently active nucleus. It is possible that the counterpart is optically faint (possibly due to a recently completed duty cycle) or is not visible due to movement or position. If the radio source is a distant background object, then the brighter jet is most likely magnified by gravitational lensing. If the radio source is located at the redshift of the cluster, then the brighter radio jet trails backward toward and past the cD galaxy to a distance of ~120 kpc, while the fainter jet is bent at a nearly orthogonal angle, ~40 kpc away from the brightest radio hotspot, in the opposite direction. These geometric offsets could be used to constrain the duty cycle history of the AGN creating the radio emission, as well as the dynamical properties of the intracluster medium.

Fermi Large Area Telescope Observations of Misaligned Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Celotti, A.; Charles, E.; Chekhtman, A.; Chen, A. W.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Conrad, J.; Davis, D. S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Malaguti, G.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Migliori, G.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nestoras, I.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Persic, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reyes, L. C.; Roth, M.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vilchez, N.; Villata, M.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

2010-09-01

Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a γ-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sources associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The γ-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the γ-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the γ-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the γ-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.

Revealing two radio-active galactic nuclei extremely near PSR J0437-4715

NASA Astrophysics Data System (ADS)

Li, Zhixuan; Yang, Jun; An, Tao; Paragi, Zsolt; Deller, Adam; Reynolds, Cormac; Hong, Xiaoyu; Wang, Jiancheng; Ding, Hao; Xia, Bo; Yan, Zhen; Guo, Li

2018-05-01

Newton's gravitational constant G may vary with time at an extremely low level. The time variability of G will affect the orbital motion of a millisecond pulsar in a binary system and cause a tiny difference between the orbital period-dependent measurement of the kinematic distance and the direct measurement of the annual parallax distance. PSR J0437-4715 is the nearest millisecond pulsar and the brightest at radio wavelengths. To explore the feasibility of achieving a parallax distance accuracy of one light-year, comparable to the recent timing result, with the technique of differential astrometry, we searched for compact radio sources quite close to PSR J0437-4715. Using existing data from the Very Large Array and the Australia Telescope Compact Array, we detected two sources with flat spectra, relatively stable flux densities of 0.9 and 1.0 mJy at 8.4 GHz and separations of 13 and 45 arcsec. With a network consisting of the Long Baseline Array and the Kunming 40-m radio telescope, we found that both sources have a point-like structure and a brightness temperature of ≥107 K. According to these radio inputs and the absence of counterparts in other bands, we argue that they are most likely the compact radio cores of extragalactic active galactic nuclei, rather than Galactic radio stars. The finding of these two radio active galactic nuclei will enable us to achieve a sub-pc distance accuracy with in-beam phase-referencing very-long-baseline interferometric observations and provide one of the most stringent constraints on the time variability of G in the near future.

Using the Medium to Teach the Medium: Radio Broadcasting.

ERIC Educational Resources Information Center

Ryland, Edwin H.

Effective broadcast education should get students to perform professionally in broadcast situations with a minimum of guidance. To do this, class assignments should include either activities similar to commercial work or on-the-job experiences at the campus or local commercial radio stations. The possibilities for such activities and experiences…

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1989-01-01

Developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) are provided. Activities of the Deep Space Network and its associated Ground Communications Facility in planning, in supporting research and technology, in implementation, and in operations are reported in space communications, radio navigation, radio science, and ground-based radio and radar astronomy.

The Telecommunications and Data Acquisition Progress Report 42-123

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1995-01-01

The progress of research programs monitored by the Jet Propulsion Laboratory's Telecommunications and Mission Operations Directorate (TMOD) are presented in this quarterly document. Areas monitored include space communications, radio navigation, radio science, ground-based radio and radar astronomy, information systems, and all other communication and research technology activities for the Deep Space Network (DSN).

Jamaican Call-In Radio: A Uses and Gratification Analysis.

ERIC Educational Resources Information Center

Surlin, Stuart H.

Noting that radio call-in programs seem to contain the elements for active audience involvement and participation, a study was conducted to examine the hypothesis that information gain and surveillance are the primary gratifications sought through call-in radio programs, especially in a culture that has a strong oral tradition and relatively few…

From Radio with Love: An Overview of the Role of Radio Observations in Understanding High-Energy Emission from Active Galaxies

NASA Technical Reports Server (NTRS)

Ojha, Roopesh

2012-01-01

The gamma-ray satellite Fermi and the ground based TeV facilities MAGIC, VERITAS and HESS have ushered in a new era in the observation of high-energy emission from active galaxies. The energy budgets of these objects have a major contribution from gamma-rays and it is simply not possible to understand their physics without high-energy observations. Though the exact mechanisms for high-energy production in galaxies remains an open question, gamma-rays typically result from interactions between high-energy particles. Via different interactions these same particles can produce radio emission. Thus the non-thermal nature of gamma-ray emission practically guarantees that high-energy emitters are also radio loud. Aside from their obvious role as a component of multiwavelength analysis, radio observations provide two crucial elements essential to understanding the source structure and physical processes of high-energy emitters: very high timing resolution and very high spatial resolution. A brief overview of the unique role played by radio observations in unraveling the mysteries of the high energy Universe as presented here.

BLAZAR SPECTRAL PROPERTIES AT 74 MHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; Funk, S.; Giroletti, M.

2013-10-01

Blazars are the most extreme class of active galactic nuclei. Despite a previous investigation at 102 MHz for a small sample of BL Lac objects and our recent analysis of blazars detected in the Westerbork Northern Sky Survey, a systematic study of the blazar spectral properties at frequencies below 100 MHz has been never carried out. In this paper, we present the first analysis of the radio spectral behavior of blazars based on the recent Very Large Array Low-frequency Sky Survey (VLSS) at 74 MHz. We search for blazar counterparts in the VLSS catalog, confirming that they are detected atmore » 74 MHz. We then show that blazars present radio-flat spectra (i.e., radio spectral indices of ∼0.5) when evaluated, which also about an order of magnitude in frequency lower than previous analyses. Finally, we discuss the implications of our findings in the context of the blazars-radio galaxies connection since the low-frequency radio data provide a new diagnostic tool to verify the expectations of the unification scenario for radio-loud active galaxies.« less

Discovery of radio emission from the brown dwarf LP944-20.

PubMed

Berger, E; Ball, S; Becker, K M; Clarke, M; Frail, D A; Fukuda, T A; Hoffman, I M; Mellon, R; Momjian, E; Murphy, N W; Teng, S H; Woodruff, T; Zauderer, B A; Zavala, R T

2001-03-15

Brown dwarfs are not massive enough to sustain thermonuclear fusion of hydrogen at their centres, but are distinguished from gas-giant planets by their ability to burn deuterium. Brown dwarfs older than approximately 10 Myr are expected to possess short-lived magnetic fields and to emit radio and X-rays only very weakly from their coronae. An X-ray flare was recently detected on the brown dwarf LP944-20, whereas previous searches for optical activity (and one X-ray search) yielded negative results. Here we report the discovery of quiescent and flaring radio emission from LP944-20, with luminosities several orders of magnitude larger than predicted by the empirical relation between the X-ray and radio luminosities that has been found for many types of stars. Interpreting the radio data within the context of synchrotron emission, we show that LP944-20 has an unusually weak magnetic field in comparison to active M-dwarf stars, which might explain the previous null optical and X-ray results, as well as the strength of the radio emissions compared to those at X-ray wavelengths.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1991-01-01

A compilation is presented of articles on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition. In space communications, radio navigation, radio science, and ground based radio and radar astronomy, activities of the Deep Space Network are reported in planning, in supporting research and technology, in implementation, and in operations. Also included is standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. In the search for extraterrestrial intelligence (SETI), implementation and operations are reported for searching the microwave spectrum.

THE COMPLEX NORTH TRANSITION REGION OF CENTAURUS A: RADIO STRUCTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neff, Susan G.; Eilek, Jean A.; Owen, Frazer N., E-mail: susan.g.neff@nasa.gov

2015-04-01

We present deep radio images of the inner ∼50 kpc of Centaurus A, taken with the Karl G. Jansky Very Large Array at 90 cm. We focus on the Transition Regions between the inner galaxy—including the active nucleus, inner radio lobes, and star-forming disk—and the outer radio lobes. We detect previously unknown extended emission around the Inner Lobes, including radio emission from the star-forming disk. We find that the radio-loud part of the North Transition Region (NTR), known as the North Middle Lobe, is significantly overpressured relative to the surrounding interstellar medium. We see no evidence for a collimated flow from themore » active galactic nucleus through this region. Our images show that the structure identified by Morganti et al. as a possible large-scale jet appears to be part of a narrow ridge of emission within the broader, diffuse, radio-loud region. This knotty radio ridge is coincident with other striking phenomena: compact X-ray knots, ionized gas filaments, and streams of young stars. Several short-lived phenomena in the NTR, as well as the frequent re-energization required by the Outer Lobes, suggest that energy must be flowing through both Transition Regions at the present epoch. We suggest that the energy flow is in the form of a galactic wind.« less

Continuum radiation from active galactic nuclei: A statistical study

NASA Technical Reports Server (NTRS)

Isobe, T.; Feigelson, E. D.; Singh, K. P.; Kembhavi, A.

1986-01-01

The physics of the continuum spectrum of active galactic nuclei (AGNs) was examined using a large data set and rigorous statistical methods. A data base was constructed for 469 objects which include radio selected quasars, optically selected quasars, X-ray selected AGNs, BL Lac objects, and optically unidentified compact radio sources. Each object has measurements of its radio, optical, X-ray core continuum luminosity, though many of them are upper limits. Since many radio sources have extended components, the core component were carefully selected out from the total radio luminosity. With survival analysis statistical methods, which can treat upper limits correctly, these data can yield better statistical results than those previously obtained. A variety of statistical tests are performed, such as the comparison of the luminosity functions in different subsamples, and linear regressions of luminosities in different bands. Interpretation of the results leads to the following tentative conclusions: the main emission mechanism of optically selected quasars and X-ray selected AGNs is thermal, while that of BL Lac objects is synchrotron; radio selected quasars may have two different emission mechanisms in the X-ray band; BL Lac objects appear to be special cases of the radio selected quasars; some compact radio sources show the possibility of synchrotron self-Compton (SSC) in the optical band; and the spectral index between the optical and the X-ray bands depends on the optical luminosity.

Soft γ-ray selected radio galaxies: favouring giant size discovery

NASA Astrophysics Data System (ADS)

Bassani, L.; Venturi, T.; Molina, M.; Malizia, A.; Dallacasa, D.; Panessa, F.; Bazzano, A.; Ubertini, P.

2016-09-01

Using the recent INTEGRAL/IBIS and Swift/BAT surveys we have extracted a sample of 64 confirmed plus three candidate radio galaxies selected in the soft gamma-ray band. The sample covers all optical classes and is dominated by objects showing a Fanaroff-Riley type II radio morphology; a large fraction (70 per cent) of the sample is made of `radiative mode' or high-excitation radio galaxies. We measured the source size on images from the NRAO VLA Sky Survey, the Faint Images of the Radio Sky at twenty-cm and the Sydney University Molonglo Sky Survey images and have compared our findings with data in the literature obtaining a good match. We surprisingly found that the soft gamma-ray selection favours the detection of large size radio galaxies: 60 per cent of objects in the sample have size greater than 0.4 Mpc while around 22 per cent reach dimension above 0.7 Mpc at which point they are classified as giant radio galaxies (GRGs), the largest and most energetic single entities in the Universe. Their fraction among soft gamma-ray selected radio galaxies is significantly larger than typically found in radio surveys, where only a few per cent of objects (1-6 per cent) are GRGs. This may partly be due to observational biases affecting radio surveys more than soft gamma-ray surveys, thus disfavouring the detection of GRGs at lower frequencies. The main reasons and/or conditions leading to the formation of these large radio structures are still unclear with many parameters such as high jet power, long activity time and surrounding environment all playing a role; the first two may be linked to the type of active galactic nucleus discussed in this work and partly explain the high fraction of GRGs found in the present sample. Our result suggests that high energy surveys may be a more efficient way than radio surveys to find these peculiar objects.

Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ran; Wu, Xue-Bing; Jiang, Linhua

We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas ×5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 ± 9.0 μ Jy beam{sup −1} and a total flux density of 88 ± 19 μ Jy. The position of themore » radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 ± 3.5) mas × (3.1 ± 1.7) mas. This corresponds to a physical scale of (40 ± 20) pc × (18 ± 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T {sub B} = (1.6 ± 1.2) × 10{sup 7} K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.« less

Optical identification of radio-loud active galactic nuclei in the ROSAT-Green-Bank sample with SDSS spectroscopy

NASA Astrophysics Data System (ADS)

Wang, De-Liang; Wang, Jian-Guo; Dong, Xiao-Bo

2009-10-01

Results of extended and refined optical identification of 181 radio/X-ray sources in the RASS-Green Bank (RGB) catalog are presented (Brinkmann et al. 1997) which have been spectroscopically observed in the Sloan Digital Sky Survey (SDSS) DR5. The SDSS spectra of the optical counterparts are modeled in a careful and self-consistent way by incorporating the host galaxy's starlight. Optical emission line parameters are presented, which are derived accurately and reliably, along with the radio 1.4-5 GHz spectral indices estimated using (non-simultaneous) archival data. For 72 sources, the identifications are presented for the first time. It is confirmed that the majority of strong radio/X-ray emitters are radio-loud active galactic nuclei (AGNs), particularly blazars. Taking advantage of the high spectral quality and resolution and our refined spectral modeling, we are able to disentangle narrow line radio galaxies (NLRGs), as vaguely termed in most previous identification work, into Seyfert II galaxies and LINERs (low-ionization nuclear emission regions), based on the standard emission line diagnostics. The NLRGs in the RGB sample, mostly belonging to 'weak line radio galaxies', are found to have optical spectra consistent predominantly with LINERs, and only a small fraction with Seyfert II galaxies. A small number of LINERs have radio power as high as 1023 - 1026 W Hz-1 at 5 GHz, being among the strongest radio emitting LINERs known so far. Two sources are identified with radio-loud narrow line Seyfert 1 galaxies (NLS1s), a class of rare objects. The presence is also confirmed of flat-spectrum radio quasars whose radio-optical-X-ray effective spectral indices are similar to those of High-energy peaked BL Lacs (HBLs), as suggested by Padovani et al., although it is still a debate as to whether this is the case for their actual spectral energy distributions.

Gravitational lensing of active galactic nuclei.

PubMed

Hewitt, J N

1995-12-05

Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes.

THE VLA-COSMOS PERSPECTIVE ON THE INFRARED-RADIO RELATION. I. NEW CONSTRAINTS ON SELECTION BIASES AND THE NON-EVOLUTION OF THE INFRARED/RADIO PROPERTIES OF STAR-FORMING AND ACTIVE GALACTIC NUCLEUS GALAXIES AT INTERMEDIATE AND HIGH REDSHIFT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargent, M. T.; Schinnerer, E.; MartInez-Sansigre, A.

2010-02-01

VLA 1.4 GHz ({sigma}{approx} 0.012 mJy) and MIPS 24 and 70 {mu}m ({sigma}{approx} 0.02 and 1.7 mJy, respectively) observations covering the 2 deg{sup 2} COSMOS field are combined with an extensive multiwavelength data set to study the evolution of the infrared (IR)-radio relation at intermediate and high redshift. With {approx}4500 sources-of which {approx}30% have spectroscopic redshifts-the current sample is significantly larger than previous ones used for the same purpose. Both monochromatic IR/radio flux ratios (q {sub 24} and q {sub 70}), as well as the ratio of the total IR and the 1.4 GHz luminosity (q {sub TIR}), are usedmore » as indicators for the IR/radio properties of star-forming galaxies and active galactic nuclei (AGNs). Using a sample jointly selected at IR and radio wavelengths in order to reduce selection biases, we provide firm support for previous findings that the IR-radio relation remains unchanged out to at least z{approx} 1.4. Moreover, based on data from {approx}150 objects we also find that the local relation likely still holds at zin [2.5, 5]. At redshift z< 1.4, we observe that radio-quiet AGNs populate the locus of the IR-radio relation in similar numbers as star-forming sources. In our analysis, we employ the methods of survival analysis in order to ensure a statistically sound treatment of flux limits arising from non-detections. We determine the observed shift in average IR/radio properties of IR- and radio-selected populations and show that it can reconcile apparently discrepant measurements presented in the literature. Finally, we also investigate variations of the IR/radio ratio with IR and radio luminosity and find that it hardly varies with IR luminosity but is a decreasing function of radio luminosity.« less

Four hot DOGs in the microwave

NASA Astrophysics Data System (ADS)

Frey, Sándor; Paragi, Zsolt; Gabányi, Krisztina Éva; An, Tao

2016-01-01

Hot dust-obscured galaxies (hot DOGs) are a rare class of hyperluminous infrared galaxies identified with the Wide-field Infrared Survey Explorer (WISE) satellite. The majority of them are at high redshifts (z ˜ 2-3), at the peak epoch of star formation in the Universe. Infrared, optical, radio, and X-ray data suggest that hot DOGs contain heavily obscured, extremely luminous active galactic nuclei (AGN). This class may represent a short phase in the life of the galaxies, signifying the transition from starburst- to AGN-dominated phases. Hot DOGs are typically radio-quiet, but some of them show mJy-level emission in the radio (microwave) band. We observed four hot DOGs using the technique of very long baseline interferometry (VLBI). The 1.7 GHz observations with the European VLBI Network (EVN) revealed weak radio features in all sources. The radio is free from dust obscuration and, at such high redshifts, VLBI is sensitive only to compact structures that are characteristic of AGN activity. In two cases (WISE J0757+5113, WISE J1603+2745), the flux density of the VLBI-detected components is much smaller than the total flux density, suggesting that ˜70-90 per cent of the radio emission, while still dominated by AGN, originates from angular scales larger than that probed by the EVN. The source WISE J1146+4129 appears a candidate compact symmetric object, and WISE J1814+3412 shows a 5.1 kpc double structure, reminiscent of hotspots in a medium-sized symmetric object. Our observations support that AGN residing in hot DOGs may be genuine young radio sources where starburst and AGN activities coexist.

Automatic recognition of coronal type II radio bursts: The ARBIS 2 method and first observations

NASA Astrophysics Data System (ADS)

Lobzin, Vasili; Cairns, Iver; Robinson, Peter; Steward, Graham; Patterson, Garth

Major space weather events such as solar flares and coronal mass ejections are usually accompa-nied by solar radio bursts, which can potentially be used for real-time space weather forecasts. Type II radio bursts are produced near the local plasma frequency and its harmonic by fast electrons accelerated by a shock wave moving through the corona and solar wind with a typi-cal speed of 1000 km s-1 . The coronal bursts have dynamic spectra with frequency gradually falling with time and durations of several minutes. We present a new method developed to de-tect type II coronal radio bursts automatically and describe its implementation in an extended Automated Radio Burst Identification System (ARBIS 2). Preliminary tests of the method with spectra obtained in 2002 show that the performance of the current implementation is quite high, ˜ 80%, while the probability of false positives is reasonably low, with one false positive per 100-200 hr for high solar activity and less than one false event per 10000 hr for low solar activity periods. The first automatically detected coronal type II radio bursts are also presented. ARBIS 2 is now operational with IPS Radio and Space Services, providing email alerts and event lists internationally.

8-12 GHz Radio Observations of Flare Activity On M dwarf CN Leo

NASA Astrophysics Data System (ADS)

Wofford, Alia; Villadsen, Jackie; Quintana, Elisa; Barclay, Thomas; Thackeray, Beverly

2018-01-01

Red dwarfs are cool stars that make up 70% of all stars. Red dwarfs can be utilized to detect potentially habitable planets but they have particularly strong magnetic activity that can be detrimental to orbiting planets’ atmospheres and habitability. A coronal mass ejection (CME) is an eruption of magnetized plasma from the star that is ejected into the interplanetary medium which can erode a planet’s atmosphere daily. Based on the sun CMEs are expected to produce very bright radio bursts along with optical flares. We are using M dwarf CN Leo, a well studied flare star that was in the K2 campaign field in summer 2017, as a template to understand the relationship between radio and optical flares and the space weather conditions impacting M dwarf planets. Using radio frequencies ranging from 0.22 GHz-12 GHz we search for simultaneous radio bursts and optical flares to infer if CMEs, flares or aurorae are occurring on the star. I will present the 8-12 GHz radio data from eight 1.5-hour observations with simultaneous optical data. CN Leo produced a bright non-thermal radio flare that lasted approximately for a day during two consecutive observations, with a gyrosynchrotron emission mechanism.

The dust masses of powerful radio galaxies: clues to the triggering of their activity

NASA Astrophysics Data System (ADS)

Tadhunter, C.; Dicken, D.; Morganti, R.; Konyves, V.; Ysard, N.; Nesvadba, N.; Ramos Almeida, C.

2014-11-01

We use deep Herschel Space Observatory observations of a 90 per cent complete sample of 32 intermediate-redshift 2Jy radio galaxies (0.05 < z < 0.7) with strong emission lines to estimate the dust masses of their host galaxies and thereby investigate the triggering mechanisms for their quasar-like AGN. The dust masses derived for the radio galaxies (7.2 × 105 < Md < 2.6 × 108 M⊙) are intermediate between those of quiescent elliptical galaxies on the one hand, and ultraluminous infrared galaxies (ULIRGs) on the other. Consistent with simple models for the co-evolution of supermassive black holes and their host galaxies, these results suggest that most radio galaxies represent the late time re-triggering of AGN activity via mergers between the host giant elliptical galaxies and companion galaxies with relatively low gas masses. However, a minority of the radio galaxies in our sample (˜20 per cent) have high, ULIRG-like dust masses, along with evidence for prodigious star formation activity. The latter objects are more likely to have been triggered in major, gas-rich mergers that represent a rapid growth phase for both their host galaxies and their supermassive black holes.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1983-01-01

Archival reports on developments in programs managed by JPL's office of Telecommunications and Data Acquisition (TDA) are presented. In space communications, radio navigation, radio science, and ground-based radio astronomy, it reports on activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, in supporting research and technology, in implementation, and in operations.

Radio Waves and Curriculum Pathways: Jamaican "At Risk" Learners Construct Media

ERIC Educational Resources Information Center

Feraria, Paulette J.

2018-01-01

This paper explores radio play as an alternative space for learning language and literacy for Jamaican students labeled as 'at-risk' learners. Through the creation of a make-believe radio station in the classroom, students developed oral language skills as a necessary precursor for social literacy. They connected reading and writing activities and…

RadioActive101 Practices

ERIC Educational Resources Information Center

Brites, Maria José; Ravenscroft, Andrew; Dellow, James; Rainey, Colin; Jorge, Ana; Santos, Sílvio Correia; Rees, Angela; Auwärter, Andreas; Catalão, Daniel; Balica, Magda; Camilleri, Anthony F.

2014-01-01

In keeping with the overarching RadioActive101 (RA101) spirit and ethos, this report is the product of collaborative and joined-up thinking from within the European consortium spread across five countries. As such, it is not simply a single voice reporting on the experiences and knowledge gained during the project. Rather it is a range of…

A MATLAB Library for Rapid Prototyping of Wireless Communications Algorithms with the Universal Software Radio Peripheral (USRP) Radio Family

DTIC Science & Technology

2013-06-01

Radio is a software development toolkit that provides signal processing blocks to drive the SDR. GNU Radio has many strong points – it is actively...maintained with a large user base, new capabilities are constantly being added, and compiled C code is fast for many real-time applications such as...programming interface (API) makes learning the architecture a daunting task, even for the experienced software developer. This requirement poses many

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1983-01-01

This publication reports on developments in programs managed by JPL's office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground based radio astronomy, it reports on activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, in supporting research and technology, in implementation and in operations. In geodynamics, the publication reports on the application of radio interferometry at microwave frequencies for geodynamic measurements. This publication also reports on implementation and operations for searching the microwave spectrum.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1991-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN). Also included is standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. In the search for extraterrestrial intelligence (SETI), 'The TDA Progress Report' reports on implementation and operations for searching the microwave spectrum. In solar system radar, it reports on the uses of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets. In radio astronomy, the areas of support include spectroscopy, very long baseline interferometry, and astrometry.

Fermi gamma-ray imaging of a radio galaxy.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cavazzuti, E; Cecchi, C; Celik, O; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Colafrancesco, S; Cominsky, L R; Conrad, J; Costamante, L; Cutini, S; Davis, D S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Finke, J; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Georganopoulos, M; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Romani, R W; Roth, M; Ryde, F; Sadrozinski, H F-W; Sambruna, R; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stawarz, Ł; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M; Hardcastle, M J; Kazanas, D

2010-05-07

The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (greater than one-half) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton-scattered relic radiation from the cosmic microwave background, with additional contribution at higher energies from the infrared-to-optical extragalactic background light. These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, as well as a promising method to probe the cosmic relic photon fields.

Chasing Low Frequency Radio Bursts from Magnetically Active Stars

NASA Astrophysics Data System (ADS)

Lynch, Christene; Murphy, Tara; Kaplan, David

2017-05-01

Flaring activity is a common characteristic of magnetically active stars. These events produce emission throughout the electromagnetic spectrum, implying a range of physical processes. A number of objects exhibit short-duration, narrow band, and highly circularly polarised (reaching 100%) radio bursts. The observed polarisation and frequency-time structure of these bursts points to a coherent emission mechanism such as the electron cyclotron maser. Due to the stochastic nature of these bursts and the sensitivity of current instruments, the number of stars where coherent emission has been detected is few, with numbers limited to a few tens of objects. Observations of a wider sample of active stars are necessary in order to establish the percentage that exhibit coherent radio bursts and to relate the observed emission characteristics to stellar magnetic properties. New wide-field, low frequency radio telescopes will probe a frequency regime that is mostly unexplored for many magnetically active stars and where coherent radio emissions are expected to be more numerous. M dwarf stars are of particular interest as they are currently favoured as most likely to host habitable planets. Yet the extreme magnetic activity observed for some M dwarf stars places some doubt on the ability of orbiting planets to host life. This presentation reports the first results from a targeted Murchison Widefield Array survey of M dwarf stars that were previously detected at 100 - 200 MHz using single dish telescopes. We will discuss robust flare-rate measurements over a high dynamic range of flare properties, as well as investigate the physical mechanism(s) behind the flares.

Information Content in Radio Waves: Student Investigations in Radio Science

NASA Astrophysics Data System (ADS)

Jacobs, K.; Scaduto, T.

2013-12-01

We describe an inquiry-based instructional unit on information content in radio waves, created in the summer of 2013 as part of a MIT Haystack Observatory (Westford, MA) NSF Research Experiences for Teachers (RET) program. This topic is current and highly relevant, addressing science and technical aspects from radio astronomy, geodesy, and atmospheric research areas as well as Next Generation Science Standards (NGSS). Projects and activities range from simple classroom demonstrations and group investigations, to long term research projects incorporating data acquisition from both student-built instrumentation as well as online databases. Each of the core lessons is applied to one of the primary research centers at Haystack through an inquiry project that builds on previously developed units through the MIT Haystack RET program. In radio astronomy, students investigate the application of a simple and inexpensive software defined radio chip (RTL-SDR) for use in systems implementing a small and very small radio telescope (SRT and VSRT). Both of these systems allow students to explore fundamental principles of radio waves and interferometry as applied to radio astronomy. In ionospheric research, students track solar storms from the initial coronal mass ejection (using Solar Dynamics Observatory images) to the resulting variability in total electron density concentrations using data from the community standard Madrigal distributed database system maintained by MIT Haystack. Finally, students get to explore very long-baseline interferometry as it is used in geodetic studies by measuring crustal plate displacements over time. Alignment to NextGen standards is provided for each lesson and activity with emphasis on HS-PS4 'Waves and Their Applications in Technologies for Information Transfer'.

A New Radio Loudness Diagnostic for Active Galaxies: A Radio-to-Mid-Infrared Parameter

NASA Technical Reports Server (NTRS)

Melendez, Marcio B.; Kraemer, S. B.; Schmitt, H. R.

2010-01-01

We have studied the relationship between the nuclear (high-resolution) radio emission, at 8.4GHz (3.6cm) and 1.4GHz (20cm), the [O IV) (gamma)25.89 micron, [Ne III] (gamma)l5.56 micron and [Ne II] (gamma)l2.81 micron emission lines and the black hole mass accretion rate for a sample of Seyfert galaxies. In order to characterize the radio contribution for the Seyfert nuclei we used the 8.4 GHz/[O IV] ratio, assuming that [0 IV] scales with the luminosity of the active galactic nuclei (AGN). From this we find that Seyfert 1 s (i.e. Seyfert 1.0s, 1.2s and 1.5s) and Seyfert 2s (i.e. Seyfert 1.8s, 1.9s and 2.0s) have similar radio contributions, relative to the AGN. On the other hand, sources in which the [Ne u] emission is dominated either by the AGN or star formation have statistically different radio contributions, with star formation dominated sources more 'radio loud', by a factor of approx.2.8 on average, than AGN dominated sources. We show that star formation dominated sources with relatively larger radio contribution have smaller mass accretion rates. Overall, we suggest that 8.4 GHz/[O IV], or alternatively, 1.4 GHz/[O IV] ratios, can be used to characterize the radio contribution, relative to the AGN, without the limitation of previous methods that rely on optical observables. Key words: Galaxy: stellar content - galaxies: Seyfert - infrared: galaxies

Radio Properties of the BAT AGNs: the FIR-radio Relation, the Fundamental Plane, and the Main Sequence of Star Formation

NASA Astrophysics Data System (ADS)

Smith, Krista Lynne; Mushotzky, Richard F.; Vogel, Stuart; Shimizu, Thomas T.; Miller, Neal

2016-12-01

We conducted 22 GHz 1″ JVLA imaging of 70 radio-quiet active galactic nuclei (AGNs) from the Swift-BAT survey. We find radio cores in all but three objects. The radio morphologies of the sample fall into three groups: compact and core-dominated, extended, and jet-like. We spatially decompose each image into core flux and extended flux, and compare the extended radio emission with that predicted from previous Herschel observations using the canonical FIR-radio relation. After removing the AGN contribution to the FIR and radio flux densities, we find that the relation holds remarkably well despite the potentially different star formation physics in the circumnuclear environment. We also compare our core radio flux densities with predictions of coronal models and scale-invariant jet models for the origin of radio emission in radio-quiet AGNs, and find general consistency with both models. However, we find that the L R/L X relation does not distinguish between star formation and non-relativistic AGN-driven outflows as the origin of radio emission in radio-quiet AGNs. Finally, we examine where objects with different radio morphologies fall in relation to the main sequence (MS) of star formation, and conclude that those AGNs that fall below the MS, as X-ray selected AGNs have been found to do, have core-dominated or jet-like 22 GHz morphologies.

The evolution of transmission security functions in modern military wideband radios

NASA Astrophysics Data System (ADS)

Matyszkiel, R.; Kaniewski, P.; Kustra, M.; Jach, J.

2017-04-01

Rapid development of advanced military command and control systems results in a dynamic growth in demand for data rate. One of the methods that make it possible to deal with the problem of limited capacity of military wireless systems is the use of broadband radios. Another one is the increase in the capacity of narrowband radios by implementing advanced modulation systems. Apart from remarkable benefits, such as the increase in system bit rate, there are also certain limitations since such radios are more sensitive to radio-electronic countermeasures, and the operation in the broad band makes it easier for the enemy to detect the radio emission. In such a situation, it is essential to define again and implement the transmission security functions into modern radios consistently. In this article, some current NATO activities are discussed, regarding the definitions of transmission security functions and the way of implementing them in radios, while paying special attention to a new element, that is to AIE radio cryptography (On Air Encryption). In the paper, the authors present an exemplary implementation of the functions in the Cognitive Radio Demonstrator using R-450C radio, the results of the examinations as well as the conclusions.

Development of an Interdisciplinary STEM Classroom Activity for Radio Receiver Technology

NASA Astrophysics Data System (ADS)

Davis, Kristina

2015-01-01

Introduction The development of a mini STEM-based classroom activity designed to integrate these two fields into one project for middle school aged students is presented here. This lesson involves small groups of students constructing a small AM radio receivers. The lesson surrounding the activity focuses on both the physical nature of electromagnetic and AC waves, circuit design, practical applications to AM radio broadcasting, and research applications of radio telescopes. These tools have shown a significant increase in the lesson's primary concept understanding among 6th grade students, as well as net positive STEM awareness and enthusiasm.Content The primary teaching point for the students to consider and learn during this lesson is 'How does scientific application influence engineering design, and vice versa?' The lesson surrounds the hands-on activity of having students construct their own AM radio receiver. Wave theory and the use of radio instruments for astronomy research are also taught in a traditional lecture format. The activity is designed to complement middle school curriculum, although it has been tested and found suitable for high school and older students as well as the general public.Evaluation and ImpactThe evaluation tool that used for the student groups in this project was a Fryer chart, which is a four panel chart with the main topic listed in the center and a single question in each of the four panels. The students are asked to answer the questions in the chart before and after they participate in the lesson activity, each time in a different colored pencil so that the scores can be given to each student before and after they participated in the activity. Student scores improved from 4.5 to 17.9 out of a total of 20 possible points. This is an overall increase of 67% of the total possible points. The questions asked on the quiz cover the range of wave theory, circuit design, and scientific explanation. This factor of improvement shows that the lesson designed for this fellowship project is effective at teaching students about each of those concepts with a single teaching activity.

The IRAS galaxy 0421+040P06: An active spiral (?) galaxy with extended radio lobes

NASA Technical Reports Server (NTRS)

Beichman, C. A.; Wynn-Williams, C. G.; Lonsdale, C. J.; Persson, S. E.; Heasley, J. N.; Miley, G. K.; Soifer, B. T.; Neugebauer, G.; Becklin, E. E.; Houck, J. R.

1984-01-01

The infrared bright galaxy 0421+040P06 detected by IRAS at 25 and 60 microns was studied at optical, infrared, and radio wavelength. It is a luminous galaxy with apparent spiral structure emitting 4 x 10 to the 37th power from far-infrared to optical wavelengths. Optical spectroscopy reveals a Seyfert 2 emission line spectrum, making 0421+040P06 the first active galaxy selected from an unbiased infrared survey of galaxies. The fact that this galaxy shows a flatter energy distribution with more 25 micron emission than other galaxies in the infrared sample may be related to the presence of an intense active nucleus. The radio observations reveal the presence of a non-thermal source that, at 6 cm, shows a prominent double lobed structure 20 to 30 kpc in size extending beyond the optical confines of the galaxy. The radio source is three to ten times larger than structures previously seen in spiral galaxies.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1994-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Telecommunications and Mission Operations Directorate (TMOD), which now includes the former Telecommunications and Data Acquisition (TDA) Office. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DS) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC).

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1993-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The papers included in this document cover satellite tracking and ground-based navigation, spacecraft-ground communications, and optical communication systems for the Deep Space Network.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1995-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Telecommunications and Mission Operations Directorate (TMOD), which now includes the former Telecommunications and Data Acquisition (TDA) Office. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC).

Radio Disappearance of the Magnetar XTE J1810-197 and Continued X-ray Timing

NASA Astrophysics Data System (ADS)

Camilo, F.; Ransom, S. M.; Halpern, J. P.; Alford, J. A. J.; Cognard, I.; Reynolds, J. E.; Johnston, S.; Sarkissian, J.; van Straten, W.

2016-04-01

We report on timing, flux density, and polarimetric observations of the transient magnetar and 5.54 s radio pulsar XTE J1810-197 using the Green Bank, Nançay, and Parkes radio telescopes beginning in early 2006, until its sudden disappearance as a radio source in late 2008. Repeated observations through 2016 have not detected radio pulsations again. The torque on the neutron star, as inferred from its rotation frequency derivative \\dot{ν }, decreased in an unsteady manner by a factor of three in the first year of radio monitoring, until approximately mid-2007. By contrast, during its final year as a detectable radio source, the torque decreased steadily by only 9%. The period-averaged flux density, after decreasing by a factor of 20 during the first 10 months of radio monitoring, remained relatively steady in the next 22 months, at an average of 0.7 ± 0.3 mJy at 1.4 GHz, while still showing day-to-day fluctuations by factors of a few. There is evidence that during this last phase of radio activity the magnetar had a steep radio spectrum, in contrast to earlier flat-spectrum behavior. No secular decrease presaged its radio demise. During this time, the pulse profile continued to display large variations; polarimetry, including of a new profile component, indicates that the magnetic geometry remained consistent with that of earlier times. We supplement these results with X-ray timing of the pulsar from its outburst in 2003 up to 2014. For the first 4 years, XTE J1810-197 experienced non-monotonic excursions in frequency derivative by at least a factor of eight. But since 2007, its \\dot{ν } has remained relatively stable near its minimum observed value. The only apparent event in the X-ray record that is possibly contemporaneous with the radio shutdown is a decrease of ≈20% in the hot-spot flux in 2008-2009, to a stable, minimum value. However, the permanence of the high-amplitude, thermal X-ray pulse, even after the (unexplained) radio demise, implies continuing magnetar activity.

Ir A.H. de Voogt: life and career of a radio pioneer

NASA Astrophysics Data System (ADS)

Strom, R. G.

2007-06-01

There are probably few radio astronomers who would be able to recall A.H. de Voogt, which is unfortunate, but at the same time unsurprising: for he published no original astronomical research, never carried out pioneering observations, nor is his name linked to either theoretical or instrumental breakthroughs. Yet he was described by the man who first observed the 21 cm hydrogen line from the Netherlands as a radio astronomy pioneer, at the very birth of the Dutch effort. He was, moreover, a trail blazer at the cutting edge of radio, not once but twice in his career. Without him it is unlikely that the 21 cm line would have been observed in the Netherlands in 1951, and arguably the H I mapping of the Milky Way under Jan Oort's leadership would have taken place much later, if at all. Radio astronomy observing itself might well have been compromised by interference had it not been for De Voogt's foresight. \\ Anthonet Hugo de Voogt (1892-1969) built, while still a teenager, one of the very first amateur radio stations (call letters VO: *** -/- - -) in Holland, earned the radio-telegrapher's diploma during his student days, and was intimately involved in the foundation of the Dutch Society for Radio-Telegraphy in 1916. Until the 1920s, he was very active in amateur radio and astronomy circles. Trained in electrical engineering at Delft, he joined the PTT (Post Office) as a telegraph engineer in 1919, worked his way through the ranks to become head of the telephone district of Breda in 1939, and was promoted to head the PTT Radio Service just days after the end of the war. As his department was responsible for overseas radio communication, he initiated a research effort to study radio propagation in the ionosphere and the effects of solar activity. To this end, he rescued a number of Würzburg-Riese 7.5-m radar antennas abandoned at the end of the war, made one available for Jan Oort's H I work, and launched a series of radio astronomical initiatives. His group also built a number of antennas, monitored solar emission, and participated in the International Geophysical Year (1957-1958).

78 FR 30268 - Information Collection Activity; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-22

... $5 million in grant funds available to facilitate the expansion of NOAA Weather Radio system coverage... space and other site resources to establish new rural NOAA Weather Radio transmitters. Eligible...

Performance Evaluation and Comparative Analysis of SubCarrier Modulation Wake-up Radio Systems for Energy-Efficient Wireless Sensor Networks

PubMed Central

Oller, Joaquim; Demirkol, Ilker; Casademont, Jordi; Paradells, Josep; Gamm, Gerd Ulrich; Reindl, Leonhard

2014-01-01

Energy-efficient communication is one of the main concerns of wireless sensor networks nowadays. A commonly employed approach for achieving energy efficiency has been the use of duty-cycled operation of the radio, where the node's transceiver is turned off and on regularly, listening to the radio channel for possible incoming communication during its on-state. Nonetheless, such a paradigm performs poorly for scenarios of low or bursty traffic because of unnecessary activations of the radio transceiver. As an alternative technology, Wake-up Radio (WuR) systems present a promising energy-efficient network operation, where target devices are only activated in an on-demand fashion by means of a special radio signal and a WuR receiver. In this paper, we analyze a novel wake-up radio approach that integrates both data communication and wake-up functionalities into one platform, providing a reconfigurable radio operation. Through physical experiments, we characterize the delay, current consumption and overall operational range performance of this approach under different transmit power levels. We also present an actual single-hop WuR application scenario, as well as demonstrate the first true multi-hop capabilities of a WuR platform and simulate its performance in a multi-hop scenario. Finally, by thorough qualitative comparisons to the most relevant WuR proposals in the literature, we state that the proposed WuR system stands out as a strong candidate for any application requiring energy-efficient wireless sensor node communications. PMID:24451452

AH-1S communication switch integration program

NASA Technical Reports Server (NTRS)

Haworth, Loran; Szoboszlay, Zoltan; Shively, Robert; Bick, Frank J.

1989-01-01

The C-6533/ARC communication system as installed on the test AH-1E Cobra helicopter was modified to allow discrete radio selection of all aircraft radios at the cyclic radio/intercommunication system switch. The current Cobra-fleet use of the C-6533 system is cumbersome, particularly during low-altitude operations. Operationally, the current system C-6533 configuration and design requires the pilot to estimate when he can safely remove his hand from an active flight control to select radios during low-altitude flight. The pilot must then physically remove his hand from the flight control, look inside the cockpit to select and verify the radio selection and then effect the selected radio transmission by activating the radio/ICS switch on the cyclic. This condition is potentially hazardous, especially during low-level flight at night in degraded weather. To improve pilot performance, communications effectiveness, and safety, manprint principles were utilized in the selection of a design modification. The modified C-6533 design was kept as basic as possible for potential Cobra-fleet modification. The communications system was modified and the design was subsequently flight-tested by the U.S. Army Aeroflightdynamics Directorate and NASA at the NASA Ames Research Center, Mountain View, California. The design modification enables the Cobra pilot to maintain hands-on flight controls while selecting radios during nap-of-the-Earth (NOE) flight without looking inside the cockpit which resulted in reduced pilot workload ratings, better pilot handling quality ratings and increased flight safety for the NOE flight environment.

Performance evaluation and comparative analysis of SubCarrier Modulation Wake-up Radio systems for energy-efficient wireless sensor networks.

PubMed

Oller, Joaquim; Demirkol, Ilker; Casademont, Jordi; Paradells, Josep; Gamm, Gerd Ulrich; Reindl, Leonhard

2013-12-19

Energy-efficient communication is one of the main concerns of wireless sensor networks nowadays. A commonly employed approach for achieving energy efficiency has been the use of duty-cycled operation of the radio, where the node's transceiver is turned off and on regularly, listening to the radio channel for possible incoming communication during its on-state. Nonetheless, such a paradigm performs poorly for scenarios of low or bursty traffic because of unnecessary activations of the radio transceiver. As an alternative technology, Wake-up Radio (WuR) systems present a promising energy-efficient network operation, where target devices are only activated in an on-demand fashion by means of a special radio signal and a WuR receiver. In this paper, we analyze a novel wake-up radio approach that integrates both data communication and wake-up functionalities into one platform, providing a reconfigurable radio operation. Through physical experiments, we characterize the delay, current consumption and overall operational range performance of this approach under different transmit power levels. We also present an actual single-hop WuR application scenario, as well as demonstrate the first true multi-hop capabilities of a WuR platform and simulate its performance in a multi-hop scenario. Finally, by thorough qualitative comparisons to the most relevant WuR proposals in the literature, we state that the proposed WuR system stands out as a strong candidate for any application requiring energy-efficient wireless sensor node communications.

Radio and γ-ray follow-up of the exceptionally high-activity state of PKS 1510-089 in 2011

DOE PAGES

Orienti, M.; Koyama, S.; D'Ammando, F.; ...

2012-11-09

In this paper, we investigate the radio and γ-ray variability of the flat spectrum radio quasar PKS 1510-089 in the time range between 2010 November and 2012 January. In this period the source showed an intense activity, with two major γ-ray flares detected in 2011 July and October. During the latter episode both the γ-ray and the radio flux density reached their historical peak. Multiwavelength analysis shows a rotation of about 380° of the optical polarization angle close in time with the rapid and strong γ-ray flare in 2011 July. An enhancement of the optical emission and an increase ofmore » the fractional polarization both in the optical and in radio bands are observed about three weeks later, close in time with another γ-ray outburst. On the other hand, after 2011 September a huge radio outburst has been detected, first in the millimetre regime followed with some time delay at centimetre down to decimetre wavelengths. This radio flare is characterized by a rising and a decaying stage, in agreement with the formation of a shock and its evolution, as a consequence of expansion and radiative cooling. Lastly, if the γ-ray flare observed in 2011 October is related to this radio outburst, then this strongly indicates that the region responsible for the γ-ray variability is not within the broad line, but a few parsecs downstream along the jet.« less

Meteor Shower observations from the Indian Sub-Continent (Visual Photographic and Radio)

NASA Astrophysics Data System (ADS)

Dabhade, R.; Savant, V.; Belapure, J.

2011-01-01

We review the present status of meteor shower observing from the Indian sub-continent. Some amateur groups are active in visual observations, although they are restricted by the lack of good observing sites. Ham radio appears to be promising as a technique to monitor the major meteor showers in this region. We present radio observations of the 2006 Quadrantids.

Post-Coma Persons Emerged from a Minimally Conscious State and Showing Multiple Disabilities Learn to Manage a Radio-Listening Activity

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Colonna, Fabio; Buonocunto, Francesca; Sacco, Valentina; Megna, Marisa; Oliva, Doretta

2012-01-01

This study assessed microswitch-based technology to enable three post-coma adults, who had emerged from a minimally conscious state but presented motor and communication disabilities, to operate a radio device. The material involved a modified radio device, a microprocessor-based electronic control unit, a personal microswitch, and an amplified…

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

NASA Astrophysics Data System (ADS)

Kapińska, A. D.; Terentev, I.; Wong, O. I.; Shabala, S. S.; Andernach, H.; Rudnick, L.; Storer, L.; Banfield, J. K.; Willett, K. W.; de Gasperin, F.; Lintott, C. J.; López-Sánchez, Á. R.; Middelberg, E.; Norris, R. P.; Schawinski, K.; Seymour, N.; Simmons, B.

2017-12-01

Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a large-scale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies ({L}{median}=4.7× {10}24 W Hz-1 sr-1) at redshifts 0.14< z< 1.0. Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high- and two as low-excitation galaxies. Two candidate HyMoRS are giant (> 1 Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

[Sentinel node detection using optonuclear probe (gamma and fluorescence) after green indocyanine and radio-isotope injections].

PubMed

Poumellec, M-A; Dejode, M; Figl, A; Darcourt, J; Haudebourg, J; Sabah, Y; Voury, A; Martaens, A; Barranger, E

2016-04-01

Assess the biopsy's feasibility of the sentinel lymph node biopsy (SLNB) using optonuclear probe after of indocyanine green (ICG) and radio-isotope (RI) injections. Twenty-one patients with a localized breast cancer and unsuspicious axillary nodes underwent a SLNB after both injections of ICG and radio-isotope. One or more SLN were identified on the 21 patients (identification rate of 100%). The median number SLN was 2 (1-3). Twenty SLN were both radio-actives and fluorescents (54.1%), 11 fluorescent only (29.7%) and 6 were only radio-actives (16.2%). Seven patients had a metastatic SLN (8 SLN overall). Among them, only one had a micrometastasic SLN, 5 others had a macrometastatic SLN and one patient had two macrometastatic SLNs. Among the 8 metastatic SLN, 5 were both fluorescent and radioactive, 2 were only fluorescent and 1 was only radioactive. Detection SLN using optonuclear probe after indocyanine green and radio-isotope injections is effective and could be, after validation by randomized trial, a reliable alternative to the blue dye injection for teams who consider that combined detection as the reference. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

A Submillimeter Perspective on the Goods Fields. II. The High Radio Power Population in the Goods-N

NASA Astrophysics Data System (ADS)

Barger, A. J.; Cowie, L. L.; Owen, F. N.; Hsu, L.-Y.; Wang, W.-H.

2017-01-01

We use ultradeep 20 cm data from the Karl G. Jansky Very Large Array and 850 μm data from SCUBA-2 and the Submillimeter Array of an 124 arcmin2 region of the Chandra Deep Field-north to analyze the high radio power ({P}20{cm}> {10}31 erg s-1 Hz-1) population. We find that 20 (42 ± 9%) of the spectroscopically identified z> 0.8 sources have consistent star formation rates (SFRs) inferred from both submillimeter and radio observations, while the remaining sources have lower (mostly undetected) submillimeter fluxes, suggesting that active galactic nucleus (AGN) activity dominates the radio power in these sources. We develop a classification scheme based on the ratio of submillimeter flux to radio power versus radio power and find that it agrees with AGN and star-forming galaxy classifications from Very Long Baseline Interferometry. Our results provide support for an extremely rapid drop in the number of high SFR galaxies above about a thousand solar masses per year (Kroupa initial mass function) and for the locally determined relation between X-ray luminosity and radio power for star-forming galaxies applying at high redshifts and high radio powers. We measure far-infrared (FIR) luminosities and find that some AGNs lie on the FIR-radio correlation, while others scatter below. The AGNs that lie on the correlation appear to do so based on their emission from the AGN torus. We measure a median radio size of 1.″0 ± 0.3 for the star-forming galaxies. The radio sizes of the star-forming galaxies are generally larger than those of the AGNs. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

The Radio Luminosity Function and Galaxy Evolution in the Coma Cluster

NASA Technical Reports Server (NTRS)

Miller, Neal A.; Hornschemeier, Ann E.; Mabasher, Bahram; Brudgesm Terrry J.; Hudson, Michael J.; Marzke, Ronald O.; Smith, Russell J.

2008-01-01

We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 (mu)Jy per 4.4" beam, we identify 249 radio sources with optical counterparts brighter than r = 22 (equivalent to M(sub r) = -13 for cluster member galaxies). Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are restricted to radio luminosities between about 10(exp 21) and 10(exp 22) W/Hz, an interesting result given that star formation dominates field radio luminosity functions below about 10(exp 23) W/Hz. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr less than or equals -20.5) make the largest contribution to the radio luminosity function at both the high (> approx. 3x10(exp 22) W/Hz) and low (< approx. 10(exp 21) W/Hz) ends. Through a stacking analysis of these optically-bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3x10(exp 19) W/Hz. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (M(sub r) approx. equals -14) dwarf ellipticals hosting strong radio AGN.

DEEP CHANDRA X-RAY IMAGING OF A NEARBY RADIO GALAXY 4C+29.30: X-RAY/RADIO CONNECTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemiginowska, Aneta; Aldcroft, Thomas L.; Burke, D. J.

2012-05-10

We report results from our deep Chandra X-ray observations of a nearby radio galaxy, 4C+29.30 (z = 0.0647). The Chandra image resolves structures on sub-arcsec to arcsec scales, revealing complex X-ray morphology and detecting the main radio features: the nucleus, a jet, hotspots, and lobes. The nucleus is absorbed (N{sub H} {approx_equal} 3.95{sup +0.27}{sub -0.33} Multiplication-Sign 10{sup 23} cm{sup -2}) with an unabsorbed luminosity of L{sub 2-10keV} {approx_equal} (5.08 {+-} 0.52) Multiplication-Sign 10{sup 43} erg s{sup -1} characteristic of Type 2 active galactic nuclei. Regions of soft (<2 keV) X-ray emission that trace the hot interstellar medium (ISM) are correlatedmore » with radio structures along the main radio axis, indicating a strong relation between the two. The X-ray emission extends beyond the radio source and correlates with the morphology of optical-line-emitting regions. We measured the ISM temperature in several regions across the galaxy to be kT {approx_equal} 0.5 keV, with slightly higher temperatures (of a few keV) in the center and in the vicinity of the radio hotspots. Assuming that these regions were heated by weak shocks driven by the expanding radio source, we estimated the corresponding Mach number of 1.6 in the southern regions. The thermal pressure of the X-ray-emitting gas in the outermost regions suggests that the hot ISM is slightly underpressured with respect to the cold optical-line-emitting gas and radio-emitting plasma, which both seem to be in a rough pressure equilibrium. We conclude that 4C+29.30 displays a complex view of interactions between the jet-driven radio outflow and host galaxy environment, signaling feedback processes closely associated with the central active nucleus.« less

Creating a Collaborative "Hot Clock": Using Smart Phones to Motivate Students' Learning in News Interviewing and Reporting

ERIC Educational Resources Information Center

Wei, Fang-Yi Flora

2016-01-01

This unit activity is integrated into the chapters on radio of the appropriate course--Survey of Mass Media, Broadcast Journalism, News Writing, Media Programing, or Communication Technology. Employing the concept of a "hot-clock radio format," the purpose of this unit activity is to motivate students' collaborative learning in news…

Gravitational lensing of active galactic nuclei.

PubMed Central

Hewitt, J N

1995-01-01

Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes. PMID:11607613

The Great Astronomical Ear.

ERIC Educational Resources Information Center

Hiatt, Blanchard

1980-01-01

Presents a description of the world's largest radio/radar antenna, the Areciba Observatory in Puerto Rico. Activities at the observatory are discussed as well as the scientific research in the field of radio astronomy. (SA)

The dependence of the soft X ray spectral slope with radio property, luminosity, and redshift, for a large sample of AGN from the Einstein IPC data base

NASA Technical Reports Server (NTRS)

Brunner, H.; Worrall, D. M.; Wilkes, Belinda J.; Elvis, Martin

1989-01-01

The dependence of the soft X-ray spectral slope on radio, optical and X-ray properties, and on redshift are reported for a large sample of Active Galactic Nuclei (AGN). The sample includes 317 optically and radio-selected AGN from a preliminary version of the Einstein Imaging Proportional Counter (IPC) quasar and AGN data base. The main results are: the difference in X-ray slope between radio-loud and radio-quiet AGN were confirmed for an independent and much larger sample of sources; a difference in X-ray slope between flat and steep radio spectrum AGN is observed only in high luminosity sub-sample; in flat radio spectrum AGNs there is an indication for a dependence of the X-ray spectral index on X-ray luminosity redshift and alpha sub 0x.

The importance of Radio Quiet Zone (RQZ) for radio astronomy

NASA Astrophysics Data System (ADS)

Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin

2013-05-01

Most of radio observatories are located in isolated areas. Since radio sources from the universe is very weak, astronomer need to avoid radio frequency interference (RFI) from active spectrum users and radio noise produced by human made (telecommunication, mobile phone, microwave user and many more. There are many observatories around the world are surrounded by a Radio Quiet Zone (RQZ), which is it was set up using public or state laws. A Radio Quiet Zone normally consists of two areas: an exclusive area in which totally radio emissions are forbidden, with restrictions for residents and business developments, and a larger (radius up to 100 km above) coordination area where the power of radio transmission limits to threshold levels. Geographical Information System (GIS) can be used as a powerful tool in mapping large areas with varying RQZ profiles. In this paper, we report the initial testing of the usage of this system in order to identify the areas were suitable for Radio Quiet Zone. Among the important parameters used to develop the database for our GIS are population density, information on TV and telecommunication (mobile phones) transmitters, road networks (highway), and contour shielding. We will also use other information gathered from on-site RFI level measurements on selected 'best' areas generated by the GIS. The intention is to find the best site for the purpose of establishing first radio quiet zones for radio telescope in Malaysia.

The Cosmic History of Hot Gas Cooling and Radio AGN Activity in Massive Early-Type Galaxies

NASA Technical Reports Server (NTRS)

Danielson, A. L. R.; Lehmer, B. D.; Alexander, D. M.; Brandt, W. M.; Luo, B.; Miller, N.; Xue, Y. Q.; Stott, J. P.

2012-01-01

We study the X-ray properties of 393 optically selected early-type galaxies (ETGs) over the redshift range of z approx equals 0.0-1.2 in the Chandra Deep Fields. To measure the average X-ray properties of the ETG population, we use X-ray stacking analyses with a subset of 158 passive ETGs (148 of which were individually undetected in X-ray). This ETG subset was constructed to span the redshift ranges of z = 0.1-1.2 in the approx equals 4 Ms CDF-S and approx equals 2 Ms CDF-N and z = 0.1-0.6 in the approx equals 250 ks E-CDF-S where the contribution from individually undetected AGNs is expected to be negligible in our stacking. We find that 55 of the ETGs are detected individually in the X-rays, and 12 of these galaxies have properties consistent with being passive hot-gas dominated systems (i.e., systems not dominated by an X-ray bright Active Galactic Nucleus; AGN). On the basis of our analyses, we find little evolution in the mean 0.5-2 keY to B-band luminosity ratio (L(sub x) /L(sub Beta) varies as [1 +z]) since z approx equals 1.2, implying that some heating mechanism prevents the gas from cooling in these systems. We consider that feedback from radio-mode AGN activity could be responsible for heating the gas. We select radio AGNs in the ETG population using their far-infrared/radio flux ratio. Our radio observations allow us to constrain the duty cycle history of radio AGN activity in our ETG sample. We estimate that if scaling relations between radio and mechanical power hold out to z approx equals 1.2 for the ETG population being studied here, the average mechanical power from AGN activity is a factor of approx equals1.4 -- 2.6 times larger than the average radiative cooling power from hot gas over the redshift range z approx equals 0-1.2. The excess of inferred AGN mechanical power from these ETGs is consistent with that found in the local Universe for similar types of galaxies.

Low-Frequency Radio Bursts and Space Weather

NASA Technical Reports Server (NTRS)

Gopalswamy, N.

2016-01-01

Low-frequency radio phenomena are due to the presence of nonthermal electrons in the interplanetary (IP) medium. Understanding these phenomena is important in characterizing the space environment near Earth and other destinations in the solar system. Substantial progress has been made in the past two decades, because of the continuous and uniform data sets available from space-based radio and white-light instrumentation. This paper highlights some recent results obtained on IP radio phenomena. In particular, the source of type IV radio bursts, the behavior of type III storms, shock propagation in the IP medium, and the solar-cycle variation of type II radio bursts are considered. All these phenomena are closely related to solar eruptions and active region evolution. The results presented were obtained by combining data from the Wind and SOHO missions.

FRESH ACTIVITY IN OLD SYSTEMS: RADIO AGNs IN FOSSIL GROUPS OF GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hess, Kelley M.; Wilcots, Eric M.; Hartwick, Victoria L., E-mail: hess@ast.uct.ac.za, E-mail: ewilcots@astro.wisc.edu, E-mail: vhartwick@wisc.edu

2012-08-15

We present the first systematic 1.4 GHz Very Large Array radio continuum survey of fossil galaxy group candidates. These are virialized systems believed to have assembled over a gigayear in the past through the merging of galaxy group members into a single, isolated, massive elliptical galaxy and featuring an extended hot X-ray halo. We use new photometric and spectroscopic data from Sloan Digital Sky Survey Data Release 7 to determine that three of the candidates are clearly not fossil groups. Of the remaining 30 candidates, 67% contain a radio-loud (L{sub 1.4GHz} > 10{sup 23} W Hz{sup -1}) active galactic nucleusmore » (AGN) at the center of their dominant elliptical galaxy. We find a weak correlation between the radio luminosity of the AGN and the X-ray luminosity of the halo suggesting that the AGN contributes to energy deposition into the intragroup medium. We only find a correlation between the radio and optical luminosity of the central elliptical galaxy when we include X-ray-selected, elliptically dominated non-fossil groups, indicating a weak relationship between AGN strength and the mass assembly history of the groups. The dominant elliptical galaxy of fossil groups is on average roughly an order of magnitude more luminous than normal group elliptical galaxies in optical, X-ray, and radio luminosities and our findings are consistent with previous results that the radio-loud fraction in elliptical galaxies is linked to the stellar mass of a population. The current level of activity in fossil groups suggests that AGN fueling continues long after the last major merger. We discuss several possibilities for fueling the AGN at the present epoch.« less

On the population of remnant Fanaroff-Riley type II radio galaxies and implications for radio source dynamics

NASA Astrophysics Data System (ADS)

Godfrey, L. E. H.; Morganti, R.; Brienza, M.

2017-10-01

The purpose of this work is two-fold: (1) to quantify the occurrence of ultrasteep spectrum remnant Fanaroff-Riley type II (FRII) radio galaxies in a 74 MHz flux-limited sample, and (2) perform Monte Carlo simulations of the population of active and remnant FRII radio galaxies to confront models of remnant lobe evolution, and to provide guidance for further investigation of remnant radio galaxies. We find that fewer than 2 per cent of FRII radio galaxies with S74 MHz > 1.5 Jy are candidate ultrasteep spectrum remnants, where we define ultrasteep spectrum as α _74 MHz^1400 MHz > 1.2. Our Monte Carlo simulations demonstrate that models involving Sedov-like expansion in the remnant phase, resulting in rapid adiabatic energy losses, are consistent with this upper limit, and predict the existence of nearly twice as many remnants with normal (not ultrasteep) spectra in the observed frequency range as there are ultrasteep spectrum remnants. This model also predicts an ultrasteep remnant fraction approaching 10 per cent at redshifts z < 0.5. Importantly, this model implies the lobes remain overpressured with respect to the ambient medium well after their active lifetime, in contrast with existing observational evidence that many FRII radio galaxy lobes reach pressure equilibrium with the external medium whilst still in the active phase. The predicted age distribution of remnants is a steeply decreasing function of age. In other words, young remnants are expected to be much more common than old remnants in flux-limited samples. For this reason, incorporating higher frequency data ≳5 GHz will be of great benefit to future studies of the remnant population.

Magnetic Dynamos and X-Ray Activity in Ultracool Dwarfs (UCDs): Surprises in the Radio Band

NASA Astrophysics Data System (ADS)

Williams, Peter K.; Cook, B. A.; Berger, E.

2014-01-01

Radio observations established early on that some brown dwarfs host kilogauss magnetic fields, despite their low temperatures and the absence of the shearing tachocline that is believed to be key to the solar dynamo. The observed radio emission is often surprisingly bright, exceeding the standard magnetic radio/X-ray (Güdel-Benz) relation by as much as five orders of magnitude. This effect is still not satisfactorily explained. In an attempt to improve matters, we have constructed and analyzed a comprehensive database of ultracool dwarfs with both radio and X-ray data, including new observations of seven targets with Chandra and the upgraded VLA. While all of the newly-observed objects were detected in the X-ray, only one was detected in the radio. These new targets are thus consistent with the standard relation, in striking contrast with some previous data. Some pairs of dwarfs with outwardly similar characteristics (spectral type, v sin i) have dramatically different emission properties, with radio/X-ray ratios that differ by two orders of magnitude. These results suggest that there is dramatic variance in ultracool magnetic activity. As we also discuss in a companion poster examining the relation between rotation and activity, variation in the topology of the magnetic field may explain the data. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution. We also acknowledge support from the NSF through Grant AST-1008361 and from NASA through Chandra Award Number G02-13007A issued by the Chandra X-ray Observatory Center, operated by the Smithsonian Astrophysical Observatory and NASA under contract NAS8-03060.

Radio galaxies dominate the high-energy diffuse gamma-ray background

DOE PAGES

Hooper, Dan; Linden, Tim; Lopez, Alejandro

2016-08-09

It has been suggested that unresolved radio galaxies and radio quasars (sometimes referred to as misaligned active galactic nuclei) could be responsible for a significant fraction of the observed diffuse gamma-ray background. In this study, we use the latest data from the Fermi Gamma-Ray Space Telescope to characterize the gamma-ray emission from a sample of 51 radio galaxies. In addition to those sources that had previously been detected using Fermi data, we report here the first statistically significant detection of gamma-ray emission from the radio galaxies 3C 212, 3C 411, and B3 0309+411B. Combining this information with the radio fluxes,more » radio luminosity function, and redshift distribution of this source class, we find that radio galaxies dominate the diffuse gamma-ray background, generating 77.2(+25.4)(-9.4)% of this emission at energies above ~1 GeV . We discuss the implications of this result and point out that it provides support for scenarios in which IceCube's high-energy astrophysical neutrinos also originate from the same population of radio galaxies.« less

On the Evolution of the Cores of Radio Sources and Their Extended Radio Emission

NASA Astrophysics Data System (ADS)

Yuan, Zunli; Wang, Jiancheng

2012-01-01

The work in this paper aims at determining the evolution and possible co-evolution of radio-loud active galactic nuclei (AGNs) and their cores via their radio luminosity functions (i.e., total and core RLFs, respectively). Using a large combined sample of 1063 radio-loud AGNs selected at low radio frequency, we investigate the RLF at 408 MHz of steep-spectrum radio sources. Our results support a luminosity-dependent evolution. Using core flux density data of the complete sample 3CRR, we investigate the core RLF at 5.0 GHz. Based on the combined sample with incomplete core flux data, we also estimate the core RLF using a modified factor of completeness. Both results are consistent and show that the comoving number density of radio cores displays a persistent decline with redshift, implying a negative density evolution. We find that the core RLF is obviously different from the total RLF at the 408 MHz band which is mainly contributed by extended lobes, implying that the cores and extended lobes could not be co-evolving at radio emission.

Future Trends in Solar Radio Astronomy and Coronal Magnetic-Field Measurements

NASA Astrophysics Data System (ADS)

Fleishman, Gregory; Nita, Gelu; Gary, Dale

Solar radio astronomy has an amazingly rich, but yet largely unexploited, potential for probing the solar corona and chromosphere. Radio emission offers multiple ways of detecting and tracking electron beams, studying chromospheric and coronal thermal structure, plasma processes, particle acceleration, and measuring magnetic fields. To turn the mentioned potential into real routine diagnostics, two major components are needed: (1) well-calibrated observations with high spatial, spectral, and temporal resolutions and (2) accurate and reliable theoretical models and fast numerical tools capable of recovering the emission source parameters from the radio data. This report gives a brief overview of the new, expanded, and planned radio facilities, such as Expanded Owens Valley Solar Array (EOVSA), Jansky Very Large Array (JVLA), Chinese Solar Radio Heliograph (CSRH), Upgraded Siberian Solar Radio Telescope (USSRT), and Frequency Agile Solar Radiotelescope (FASR) with the emphasis on their ability to measure the coronal magnetic fields in active regions and flares. In particular, we emphasize the new tools for 3D modeling of the radio emission and forward fitting tools in development needed to derive the magnetic field data from the radio measurements.

On the origins of part-time radio pulsars

NASA Astrophysics Data System (ADS)

Zhang, Bing; Gil, Janusz; Dyks, Jaroslaw

2007-01-01

Growing evidence suggests that some radio pulsars only act sporadically. These `part-time' pulsars include long-term nulls, quasi-periodic radio flares in PSR B1931+24, as well as the so-called Rotating Radio Transients (RRATs). Based on the assumption that these objects are isolated neutron stars similar to conventional radio pulsars, we discuss two possible interpretations to the phenomenon. The first interpretation suggests that these objects are pulsars slightly below the radio emission `death line', which become occasionally active only when the conditions for pair production and coherent emission are satisfied. The second interpretation invokes a radio emission direction reversal in conventional pulsars, as has been introduced to interpret the peculiar mode changing phenomenon in PSR B1822-09. In this picture, our line of sight misses the main radio emission beam of the pulsar but happens to sweep the emission beam when the radio emission direction is reversed. These part-time pulsars are therefore the other half of `nulling' pulsars. We suggest that X-ray observations may provide clues to differentiate between these two possibilities.

Fermi Gamma-Ray Imaging of a Radio Galaxy

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-04-01

The Fermi Gamma-ray Space Telescope has detected the γ-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved γ-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy γ-rays, the lobe flux constitutes a considerable portion (greater than one-half) of the total source emission. The γ-ray emission from the lobes is interpreted as inverse Compton–scattered relic radiation from the cosmic microwave background, with additional contribution at higher energies from the infrared-to-optical extragalactic background light. In conclusion, these measurements provide γ-raymore » constraints on the magnetic field and particle energy content in radio galaxy lobes, as well as a promising method to probe the cosmic relic photon fields.« less

AGN jets under the microscope: A divide? Doctoral Thesis Award Lecture 2011

NASA Astrophysics Data System (ADS)

Karouzos, M.; Britzen, S.; Witzel, A.; Zensus, A. J.; Eckart, A.

2012-06-01

A new paradigm for active galactic jet kinematics has emerged through detailed investigations of BL Lac objects using very long baseline radio interferometry. In this new scheme, most, if not all, jet components appear to remain stationary with respect to the core but show significant non-radial motions. This paper presents results from our kinematic investigation of the jets of a statistically complete sample of radio-loud flat-spectrum active galaxies, focusing on the comparison between the jet kinematic properties of BL Lacs and flat-spectrum radio-quasars. It is shown that there is a statistically significant difference between the kinematics of the two AGN classes, with BL Lacs showing more bent jets, that are wider and show slower movement along the jet axis, compared to flat-spectrum radio-quasars. This is interpreted as evidence for helically structured jets.

DISCOVERY OF γ -RAY EMISSION FROM THE RADIO-INTERMEDIATE QUASAR III ZW 2: VIOLENT JET ACTIVITY WITH INTRADAY γ -RAY VARIABILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Neng-Hui; Xin, Yu-Liang; Fan, Yi-Zhong

2016-10-01

III Zw 2 is the prototype of radio-intermediate quasars. Although there is the evidence of possessing strong jet, significant γ -ray emission has not been reported before. In this work, we carry out a detailed analysis of the latest Fermi -LAT Pass  8 data. No significant γ -ray signal has been detected in the time-averaged 7-year Fermi -LAT data of III Zw 2; however, we have identified two distinct γ -ray flares with isotropic luminosities of ∼10{sup 45} erg s{sup −1}. Multiwavelength data analysis (also including the optical photometric observations from Yunnan Observatories) are presented and the main finding ismore » simultaneous optical and γ -ray flares of III Zw 2 appearing in 2009 November. Violent γ -ray variability with a doubling timescale of 2.5 hr was detected in another γ -ray flare in May 2010, for which the 3-hr γ -ray peak flux is ∼250 times of the average flux in 7 years. Rather similar behaviors are observed in blazars and the blazar model can reasonably reproduce the spectral energy distribution of III Zw 2 in a wide energy range, strongly suggesting that its central engine resembles that of blazars. In view of its core, which shares radio similarities with young radio sources, together with weak extended radio lobe emission, we suggest that III Zw 2 harbors a recurrent activity core and thus serves as a valuable target for investigating the fueling and triggering of the activity in radio-loud active galactic nuclei.« less

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1987-01-01

Archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) are provided. Activities of the Deep Space Network (DSN) in space communications, radio navigation, radio science, and ground-based radio astronomy are reported. Also included are the plans, supporting research and technology, implementation and operations for the Ground Communications Facility (GCF). In geodynamics, the publication reports on the application of radio interferometry at microwave frequencies for geodynamic measurements. In the search for extraterrestrial intelligence (SETI), it reports on implementation and operations for searching the microwave spectrum.

The Radio-X-ray Relation in Cool Stars: Are We Headed Toward a Divorce?

NASA Astrophysics Data System (ADS)

Forbrich, J.; Wolk, S. J.; Güdel, M.; Benz, A.; Osten, R.; Linsky, J. L.; McLean, M.; Loinard, L.; Berger, E.

2011-12-01

This splinter session was devoted to reviewing our current knowledge of correlated X-ray and radio emission from cool stars in order to prepare for new large radio observatories such as the EVLA. A key interest was to discuss why the X-ray and radio luminosities of some cool stars are in clear breach of a correlation that holds for other active stars, the so-called Güdel-Benz relation. This article summarizes the contributions whereas the actual presentations can be accessed on the splinter website.

A physical classification scheme for blazars

NASA Astrophysics Data System (ADS)

Landt, Hermine; Padovani, Paolo; Perlman, Eric S.; Giommi, Paolo

2004-06-01

Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars based on the strength of their emission lines. This is performed rather arbitrarily by defining a diagonal line in the Ca H&K break value-equivalent width plane, following Marchã et al. We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS) and 2-Jy radio survey and find a significant bimodality for the narrow emission line [OIII]λ5007. This suggests the presence of two physically distinct classes of radio-loud active galactic nuclei (AGN). We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII]λ5007-[OII]λ3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars.

The February 15 2011 CME-CME interaction and possibly associated radio emission

NASA Astrophysics Data System (ADS)

Magdalenic, Jasmina; Temmer, Manuela; Krupar, Vratislav; Marque, Christophe; Veronig, Astrid; Eastwood, Jonathan

2017-04-01

On February 15, 2011 a particular, continuum-like radio emission was observed by STEREO WAVES and WIND WAVES spacecraft. The radio event appeared to be associated with the complex interaction of two coronal mass ejections (CMEs) successively launched (February 14 and February 15) from the same active region. Although the CME-CME interaction was widely studied (e.g. Temmer et al., 2014, Maricic et al., 2014, Mishra & Srivastava, 2014) none of the analyses confirmed an association with the continuum-like radio emission. The usual method of establishing temporal coincidence of radio continuum and a CME-CME interaction is not applicable in this event due to a complex and long-lasting interaction of the CMEs. Therefore, we performed radio triangulation studies (see also Magdalenic et al., 2014) which provided us with the 3D source positions of the radio emission. Comparison of the positions of radio sources and the reconstructed positions of the interacting CMEs, shows that the source position of the continuum-like radio emission is about 0.5 AU away from the interacting CMEs. We can therefore concluded that, in this event, the continuum-like emission is not the radio signature of the CME-CME interaction.

RADIO PROPERTIES OF THE BAT AGNs: THE FIR–RADIO RELATION, THE FUNDAMENTAL PLANE, AND THE MAIN SEQUENCE OF STAR FORMATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Krista Lynne; Mushotzky, Richard F.; Vogel, Stuart

We conducted 22 GHz 1″ JVLA imaging of 70 radio-quiet active galactic nuclei (AGNs) from the Swift -BAT survey. We find radio cores in all but three objects. The radio morphologies of the sample fall into three groups: compact and core-dominated, extended, and jet-like. We spatially decompose each image into core flux and extended flux, and compare the extended radio emission with that predicted from previous Herschel observations using the canonical FIR–radio relation. After removing the AGN contribution to the FIR and radio flux densities, we find that the relation holds remarkably well despite the potentially different star formation physics inmore » the circumnuclear environment. We also compare our core radio flux densities with predictions of coronal models and scale-invariant jet models for the origin of radio emission in radio-quiet AGNs, and find general consistency with both models. However, we find that the L {sub R}/ L {sub X} relation does not distinguish between star formation and non-relativistic AGN-driven outflows as the origin of radio emission in radio-quiet AGNs. Finally, we examine where objects with different radio morphologies fall in relation to the main sequence (MS) of star formation, and conclude that those AGNs that fall below the MS, as X-ray selected AGNs have been found to do, have core-dominated or jet-like 22 GHz morphologies.« less

The Radio JOVE Project

NASA Astrophysics Data System (ADS)

Garcia, L.; Thieman, J.; Higgins, C.

1999-09-01

Radio JOVE is an interactive educational activity which brings the radio sounds of Jupiter and the Sun to students, teachers, and the general public. This is accomplished through the construction of a simple radio telescope kit and the use of a real-time radio observatory on the Internet. Our website (http://radiojove.gsfc.nasa.gov/) will contain science information, instruction manuals, observing guides, and education resources for students and teachers. Our target audience is high school science classes, but subjects can be tailored to college undergraduate physics and astronomy courses or even to middle school science classes. The goals of the project are: 1) Educate people about planetary and solar radio astronomy, space physics, and the scientific method 2) Provide teachers and students with a hands-on radio astronomy exercise as a science curriculum support activity by building and using a simple radio telescope receiver/antenna kit 3) Create the first ever online radio observatory which provides real-time data for those with internet access 4) Allow interactions among participating schools by facilitating exchanges of ideas, data, and observing experiences. Our current funding will allow us to impact 100 schools by partially subsidizing their participation in the program. We expect to expand well beyond this number as publicity and general interest increase. Additional schools are welcome to fully participate, but we will not be able to subsidize their kit purchases. We hope to make a wide impact among the schools by advertising through appropriate newsletters, space grant consortia, the INSPIRE project (http://image.gsfc.nasa.gov/poetry/inspire/), electronic links, and science and education meetings. We would like to acknoledge support from the NASA/GSFC Director's Discretionary Fund, the STScI IDEAS grant program and the NASA/GSFC Space Science Data Operations Office.

Teaching where there are no schools.

PubMed

Helwig, J F; Friend, J

1985-01-01

An experimental project designed to investigate the feasibility of using radio as a medium of instruction in the teaching of elementary school mathematics, the Radio Mathematics Project, which was located in Nicaragua from mid-1974 to early 1979, developed mathematics lessons for the first 4 years of elementary school. These lessons -- daily radio broadcasts plus postbroadcast activities conducted by the classroom teachers -- proved to be successful in improving the students' mathematics achievement. The cost of widescale implementation of the materials was estimated to be well within Nicaragua's budget. The success of the project can be attributed largely to the innovative style of the broadcast lessons, a style characterized as "interactive" in recognition of its mimicry of a conversation between students and teacher. The interactive lesson style is easily adapted to the teaching of many other subjects and has been used, with minor modifications, to teach English as a 2nd language and initial reading. In all these settings, the lessons provide daily instruction and are intended to replace rather than supplement existing instruction in the subject matter. Each lesson consists of a broadcast portion of the lesson carries the major burden of instruction. The interactive radio lessons are designed to provide direct instruction to the students. The radio teachers explain concepts, provide examples, and guide the students in the completion of exercises. The students listening to the radio lessons are expected to participate actively. After every student response, the radio gives the correct response so that the children can immediately compare their own responses with the correct one. Segmented structure is characteristic of the radio lessons used in all 3 projects mentioned. Radio Math's lessons are reinforced by rigorous research to validate their teaching effectiveness.

Radio continuum properties of luminous infrared galaxies. Identifying the presence of an AGN in the radio

NASA Astrophysics Data System (ADS)

Vardoulaki, E.; Charmandaris, V.; Murphy, E. J.; Diaz-Santos, T.; Armus, L.; Evans, A. S.; Mazzarella, J. M.; Privon, G. C.; Stierwalt, S.; Barcos-Muñoz, L.

2015-02-01

Context. Luminous infrared galaxies (LIRGs) are systems enshrouded in dust, which absorbs most of their optical/UV emission and radiates it again in the mid- and far-infrared. Radio observations are largely unaffected by dust obscuration, enabling us to study the central regions of LIRGs in an unbiased manner. Aims: The main goal of this project is to examine how the radio properties of local LIRGs relate to their infrared spectral characteristics. Here we present an analysis of the radio continuum properties of a subset of the Great Observatories All-sky LIRG Survey (GOALS), which consists of 202 nearby systems (z< 0.088). Our radio sample consists of 35 systems, containing 46 individual galaxies, that were observed at both 1.49 and 8.44 GHz with the VLA with a resolution of about 1 arcsec (FWHM). The aim of the project is to use the radio imagery to probe the central kpc of these LIRGs in search of active galactic nuclei (AGN). Methods: We used the archival data at 1.49 and 8.44 GHz to create radio-spectral-index maps using the standard relation between flux density Sν and frequency ν, Sν ~ ν- α, where α is the radio spectral index. By studying the spatial variations in α, we classified the objects as radio-AGN, radio-SB, and AGN/SB (a mixture). We identified the presence of an active nucleus using the radio morphology, deviations from the radio/infrared correlation, and spatially resolved spectral index maps, and then correlated this to the usual mid-infrared ([NeV]/[NeII] and [OIV]/[NeII] line ratios and equivalent width of the 6.2 μm PAH feature) and optical (BPT diagram) AGN diagnostics. Results: We find that 21 out of the 46 objects in our sample (~45%) are radio-AGN, 9 out of the 46 (~20%) are classified as starbursts (SB) based on the radio analysis, and 16 (~35%) are AGN/SB. After comparing to other AGN diagnostics we find 3 objects out of the 46 (~7%) that are identified as AGN based on the radio analysis, but are not classified as such based on the mid-infrared and optical AGN diagnostics presented in this study. Appendix A is available in electronic form at http://www.aanda.orgVLA images as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/A4

Radio afterglow rebrightening: evidence for multiple active phases in gamma-ray burst central engines

NASA Astrophysics Data System (ADS)

Li, Long-Biao; Zhang, Zhi-Bin; Rice, Jared

2015-09-01

The rebrightening phenomenon is an interesting feature in some X-ray, optical, and radio afterglows of gamma-ray bursts (GRBs). Here, we propose a possible energy-supply assumption to explain the rebrightenings of radio afterglows, in which the central engine with multiple active phases can supply at least two GRB pulses in a typical GRB duration time. Considering the case of double pulses supplied by the central engine, the double pulses have separate physical parameters, except for the number density of the surrounding interstellar medium (ISM). Their independent radio afterglows are integrated by the ground detectors to form the rebrightening phenomenon. In this Letter, we firstly simulate diverse rebrightening light curves under consideration of different and independent physical parameters. Using this assumption, we also give our best fit to the radio afterglow of GRB 970508 at three frequencies of 1.43, 4.86, and 8.46 GHz. We suggest that the central engine may be active continuously at a timescale longer than that of a typical GRB duration time as many authors have suggested (e.g., Zhang et al., Astrophys. J. 787:66, 2014; Gao and Mészáros, Astrophys. J. 802:90, 2015), and that it may supply enough energy to cause the long-lasting rebrightenings observed in some GRB afterglows.

1.4 GHz on the Fundamental Plane of black hole activity

NASA Astrophysics Data System (ADS)

Saikia, Payaswini; Körding, Elmar; Dibi, Salome

2018-06-01

The Fundamental Plane (FP) of black hole activity is an empirical relationship between the O III/X-ray luminosity depicting the accretion power, the radio luminosity as a probe of the instantaneous jet power and the mass of the black hole. For the first time, we use the 1.4 GHz FIRST radio luminosities on the optical FP, to investigate whether or not Faint Images of the Radio Sky at Twenty-Centimetres (FIRST) fluxes can trace nuclear activity. We use an SDSS-FIRST cross-correlated sample of 10 149 active galaxies and analyse their positioning on the optical FP. We focus on various reasons that can cause the discrepancy between the observed FIRST radio fluxes and the theoretically expected core radio fluxes, and show that FIRST fluxes are heavily contaminated by non-nuclear, extended components and other environmental factors. We show that the subsample of `compact sources', which should have negligible lobe contribution, statistically follow the FP when corrected for relativistic beaming, while all the other sources lie above the plane. The sample of low-ionization nuclear emission-line regions (LINERs), which should have negligible lobe and beaming contribution, also follow the FP. A combined fit of the low-luminosity AGN and the X-ray binaries, with the LINERs, results in the relation log LR = 0.77 log L_{O III} + 0.69 log M. Assuming that the original FP relation is correct, we conclude that 1.4 GHz FIRST fluxes do not trace the pure `core' jet and instantaneous nuclear activity in the AGN, and one needs to be careful while using it on the FP of black hole activity.

Lunar Radio Telescopes: A Staged Approach for Lunar Science, Heliophysics, Astrobiology, Cosmology, and Exploration

NASA Technical Reports Server (NTRS)

Lazio, Joseph; Bowman, Judd D.; Burns, Jack O.; Farrell, W. M.; Jones, D. L.; Kasper, J. C.; MacDowall, R. J.; Stewart, K. P.; Weiler, K.

2012-01-01

Observations with radio telescopes address key problems in cosmology, astrobiology, heliophysics, and planetary science including the first light in the Universe (Cosmic Dawn), magnetic fields of extrasolar planets, particle acceleration mechanisms, and the lunar ionosphere. The Moon is a unique science platform because it allows access to radio frequencies that do not penetrate the Earth's ionosphere and because its far side is shielded from intense terrestrial emissions. The instrument packages and infrastructure needed for radio telescopes can be transported and deployed as part of Exploration activities, and the resulting science measurements may inform Exploration (e.g., measurements of lunar surface charging). An illustrative roadmap for the staged deployment of lunar radio telescopes

VizieR Online Data Catalog: Blazars equivalent widths and radio luminosity (Landt+, 2004)

NASA Astrophysics Data System (ADS)

Landt, H.; Padovani, P.; Perlman, E. S.; Giommi, P.

2004-07-01

Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars based on the strength of their emission lines. This is performed rather arbitrarily by defining a diagonal line in the Ca H&K break value-equivalent width plane, following Marcha et al. (1996MNRAS.281..425M). We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS, Cat. and ) and 2-Jy radio survey and find a significant bimodality for the narrow emission line [OIII]{lambda}5007. This suggests the presence of two physically distinct classes of radio-loud active galactic nuclei (AGN). We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII]{lambda}5007-[OII]{lambda}3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars. (4 data files).

47 CFR 214.4 - Planned actions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... COORDINATION OF THE RADIO SPECTRUM DURING A WARTIME EMERGENCY § 214.4 Planned actions. (a) Whenever it is... the use of the radio spectrum in areas of active combat, where such control is necessary to the...

Tunable radio-frequency photonic filter based on an actively mode-locked fiber laser.

PubMed

Ortigosa-Blanch, A; Mora, J; Capmany, J; Ortega, B; Pastor, D

2006-03-15

We propose the use of an actively mode-locked fiber laser as a multitap optical source for a microwave photonic filter. The fiber laser provides multiple optical taps with an optical frequency separation equal to the external driving radio-frequency signal of the laser that governs its repetition rate. All the optical taps show equal polarization and an overall Gaussian apodization, which reduces the sidelobes. We demonstrate continuous tunability of the filter by changing the external driving radio-frequency signal of the laser, which shows good fine tunability in the operating range of the laser from 5 to 10 GHz.

Radio detections of southern ultracool dwarfs

NASA Astrophysics Data System (ADS)

Lynch, C.; Murphy, T.; Ravi, V.; Hobbs, G.; Lo, K.; Ward, C.

2016-04-01

We report the results of a volume-limited survey using the Australia Telescope Compact Array to search for transient and quiescent radio emission from 15 Southern hemisphere ultracool dwarfs. We detect radio emission from 2MASSW J0004348-404405 increasing the number of radio loud ultracool dwarfs to 22. We also observe radio emission from 2MASS J10481463-3956062 and 2MASSI J0339352-352544, two sources with previous radio detections. The radio emission from the three detected sources shows no variability or flare emission. Modelling this quiescent emission we find that it is consistent with optically thin gyrosynchrotron emission from a magnetosphere with an emitting region radius of (1-2)R*, magnetic field inclination 20°-80°, field strength ˜10-200 G, and power-law electron density ˜104-108 cm-3. Additionally, we place upper limits on four ultracool dwarfs with no previous radio observations. This increases the number of ultracool dwarfs studied at radio frequencies to 222. Analysing general trends of the radio emission for this sample of 15 sources, we find that the radio activity increases for later spectral types and more rapidly rotating objects. Furthermore, comparing the ratio of the radio to X-ray luminosities for these sources, we find 2MASS J10481463-3956062 and 2MASSI J0339352-352544 violate the Güdel-Benz relation by more than two orders of magnitude.

Radio Selection of the Most Distant Galaxy Clusters

NASA Astrophysics Data System (ADS)

Daddi, E.; Jin, S.; Strazzullo, V.; Sargent, M. T.; Wang, T.; Ferrari, C.; Schinnerer, E.; Smolčić, V.; Calabró, A.; Coogan, R.; Delhaize, J.; Delvecchio, I.; Elbaz, D.; Gobat, R.; Gu, Q.; Liu, D.; Novak, M.; Valentino, F.

2017-09-01

We show that the most distant X-ray-detected cluster known to date, Cl J1001 at {z}{spec}=2.506, hosts a strong overdensity of radio sources. Six of them are individually detected (within 10\\prime\\prime ) in deep 0\\buildrel{\\prime\\prime}\\over{.} 75 resolution VLA 3 GHz imaging, with {S}3{GHz}> 8 μ {Jy}. Of the six, an active galactic nucleus (AGN) likely affects the radio emission in two galaxies, while star formation is the dominant source powering the remaining four. We searched for cluster candidates over the full COSMOS 2 deg2 field using radio-detected 3 GHz sources and looking for peaks in {{{Σ }}}5 density maps. Cl J1001 is the strongest overdensity by far with > 10σ , with a simple {z}{phot}> 1.5 preselection. A cruder photometric rejection of z< 1 radio foregrounds leaves Cl J1001 as the second strongest overdensity, while even using all radio sources Cl J1001 remains among the four strongest projected overdensities. We conclude that there are great prospects for future deep and wide-area radio surveys to discover large samples of the first generation of forming galaxy clusters. In these remarkable structures, widespread star formation and AGN activity of massive galaxy cluster members, residing within the inner cluster core, will ultimately lead to radio continuum as one of the most effective means for their identification, with detection rates expected in the ballpark of 0.1-1 per square degree at z≳ 2.5. Samples of hundreds such high-redshift clusters could potentially constrain cosmological parameters and test cluster and galaxy formation models.

VizieR Online Data Catalog: Star formation in active and normal galaxies (Tsai+, 2015)

NASA Astrophysics Data System (ADS)

Tsai, M.; Hwang, C.-Y.

2015-11-01

We selected 104 active galaxies from the lists of Melendez et al. (2010MNRAS.406..493M), Condon et al. 1991 (cat. J/ApJ/378/65), and Ho & Ulvestad 2001 (cat. J/ApJS/133/77). Most of the sources are identified as Active Galactic Nuclei (AGNs), and a few of them are classified as Luminous InfraRed Galaxies (LIRGs). We obtained 3.6 and 8μm infrared images of these galaxies from the Spitzer Archive (http://sha.ipac.caltech.edu/applications/Spitzer/SHA/) and 8GHz images from the VLA archive (http://archive.nrao.edu/archive/archiveimage.html). We also selected a nearby AGN sub-sample containing 21 radio-selected AGNs for further spatial analysis. We selected 25 nearby AGNs exhibiting no detected radio emission in order to compare with the results of the radio-selected sources. For comparison, we also selected normal galaxies with distances less than 15Mpc from the catalog of Tully 1994 (see cat. VII/145). We only selected the galaxies that have Spitzer archive data and are not identified as AGNs in either the Veron-Cetty & Veron 2006 (see cat. VII/258) AGN catalog or in the NED database (http://ned.ipac.caltech.edu/). Our results for the radio-selected and the non-radio-selected active galaxies are listed in Table1, and those for the normal galaxies are listed in Table2. (2 data files).

The Structure of Solar Active Regions

NASA Astrophysics Data System (ADS)

Vourlidas, A.; Bastian, T. S.

1992-05-01

In past years, x-ray observations of solar active regions have lead to the expectation of greater brightness temperatures at radio wavelengths than those typically observed. It has been suggested that cool plasma in the corona along the line of sight attenuates radio emission via free-free absorption. If such plasma is present, it has consequences for both the microwave spectrum and its polarization properties. In order to test these ideas, high quality radio and x-ray maps are required. We present a comprehensive set of observations of a large solar active region (NOAO/USAF number 5131) made during the IAU sanctioned International Solar Month in September, 1988. The VLA was used to image the Sun in the 90, 20, 6 and 3.6 cm bands between 1--4 September. To improve the image quality we used the technique of frequency synthesis at 3.6, 6 and 20 cm. The final maps are among the best in dynamic range yet obtained. In addition to the radio maps, the data base includes images from the SMM XRP in Fe XVII, magnetograms, and Hα observations. We reconcile the x-ray and radio observations with a simple model which differs somewhat from past models. Rather than relying on a screen of cool plasma between the source and the observer, we take explicit account of the highly inhomogeneous structure of solar active regions. We briefly compare and contrast the consequences of this model with existing models.

Recurrent active regions related to metric radio continuum emissions and the interplanetary magnetic sector structure

NASA Technical Reports Server (NTRS)

Sakurai, K.

1972-01-01

Active heliographic longitudes at the sun are investigated by using the observational data for long-lived metric continuum noise sources. It is shown that, for the period from 1963 to 1969, the number of such longitudes was four in general and these longitudes were very stable for this radio activity since 1963. A discussion is given on the relationship between those longitudes and the sector structure of the interplanetary magnetic field.

Solar radio continuum storms

NASA Technical Reports Server (NTRS)

1974-01-01

Radio noise continuum emission observed in metric and decametric wave frequencies is discussed. The radio noise is associated with actively varying sunspot groups accompanied by the S-component of microwave radio emissions. It is shown that the S-component emission in microwave frequencies generally occurs several days before the emission of the noise continuum storms of lower frequencies. It is likely that energetic electrons, 10 to 100 Kev, accelerated in association with the variation of sunspot magnetic fields, are the sources of the radio emissions. A model is considered to explain the relation of burst storms on radio noise. An analysis of the role of energetic electrons on the emissions of both noise continuum and type III burst storms is presented. It is shown that instabilities associated with the electrons and their relation to their own stabilizing effects are important in interpreting both of these storms.

Near Earth space sporadic radio emission busts occurring during sunrise

NASA Technical Reports Server (NTRS)

Dudnik, A. V.; Zaljubovsky, I. I.; Kartashev, V. M.; Lasarev, A. V.; Shmatko, E. S.

1985-01-01

During the period of low solar activity at sunrise the effect of sporadic high frequency near Earth space radio emission was experimentally discovered at middle latitudes. The possible mechanism of its origin is discussed.

Characterizing Interference in Radio Astronomy Observations through Active and Unsupervised Learning

NASA Technical Reports Server (NTRS)

Doran, G.

2013-01-01

In the process of observing signals from astronomical sources, radio astronomers must mitigate the effects of manmade radio sources such as cell phones, satellites, aircraft, and observatory equipment. Radio frequency interference (RFI) often occurs as short bursts (< 1 ms) across a broad range of frequencies, and can be confused with signals from sources of interest such as pulsars. With ever-increasing volumes of data being produced by observatories, automated strategies are required to detect, classify, and characterize these short "transient" RFI events. We investigate an active learning approach in which an astronomer labels events that are most confusing to a classifier, minimizing the human effort required for classification. We also explore the use of unsupervised clustering techniques, which automatically group events into classes without user input. We apply these techniques to data from the Parkes Multibeam Pulsar Survey to characterize several million detected RFI events from over a thousand hours of observation.

Major and Daytime Meteor Showers using Global Radio Meteor Observations covering the period 2001-2016

NASA Astrophysics Data System (ADS)

Ogawa, Hiroshi; Steyaert, Christian

2017-10-01

With radio, it is possible to observe meteor activity even in bad weather and during daytime. The research in this paper succeeded in detecting the important stream features, such as peak time, peak level and FWHM (Full Width Half Maximum) in not only major streams but also daytime meteor showers, using worldwide radio forward scattering data covering the period 2001-2016.

Performance Analysis on the Coexistence of Multiple Cognitive Radio Networks

DTIC Science & Technology

2015-05-28

the scarce spectrum resources. Cognitive radio is a key in minimizing the spectral congestion through its adaptability, where the radio parameters...static allocation of spectrum results in congestion in some parts of the spectrum and non use in some others, therefore, spectra utilization is...well as the secondary user (SU) activities in multiple CR networks. It is shown that the scheduler provided much needed gain during congestions . However

Amateur Radio On The International Space Station (ARISS) - The First Educational Outreach Program On ISS

NASA Technical Reports Server (NTRS)

Conley, Carolynn Lee; Bauer, Frank H.; Brown, Deborah A.; White, Rosalie

2002-01-01

Amateur Radio on the International Space Station (ARISS) represents the first educational outreach program that is flying on the International Space Station (ISS). The astronauts and cosmonauts will work hard on the International Space Station, but they plan to take some time off for educational activities with schools. The National Aeronautics and Space Administration s (NASA s) Education Division is a major supporter and sponsor of this student outreach activity on the ISS. This meets NASA s educational mission objective: To inspire the next generation of explorers.. .as only NASA can. The amateur radio community is helping to enrich the experience of those visiting and living on the station as well as the students on Earth. Through ARISS sponsored hardware and activities, students on Earth get a first-hand feel of what it is like to live and work in space. This paper will discuss the educational outreach accomplishments of ARISS, the school contact process, the ARISS international cooperation and volunteers, and ISS Ham radio plans for the future.

X-ray inverse Compton emission from the radio halo of M87

NASA Technical Reports Server (NTRS)

Feigelson, E. D.

1984-01-01

A significant fraction of known galaxies contain an active galactic nucleus (AGN) at their cores, the site of violent activity and non-stellar radiation seen across the entire electromagnetic spectrum. This activity is thought to be due to the accretion of gas onto a massive black hole. A fraction of AGNs also eject collimated beams of energetic material, usually seen by virtue of its synchrotron emission in the radio band. Efforts to study these jets from AGNs in the X-ray band with the Einstein Observatory has led to several detections, most notably the jets in the nearby radio galaxies Centaurus A and Virgo A = M87. In their study of M87, Schreier, Gorenstein and Feigelson (1982) noted that, in addition to the synchrotron jet 10"-20" from the nucleus, X-rays appear to be generated in the diffuse radio halo 2'-5' from the nucleus. This finding may be particularly important as it may constitute the first known case of X-ray inverse Compton emission from AGN ejecta, allowing for the first time direct determination of the magnetic field strengths.

Discovery of a red quasar with recurrent activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandi, S.; Baes, M.; Gentile, G.

2014-07-01

We report a new double-double radio quasar (DDRQ) J0746+4526 which exhibits two cycles of episodic activity. From radio continuum observations at 607 MHz using the Giant Metrewave Radio Telescope and 1400 MHz from the Faint Images of the Radio Sky at Twenty-cm survey we confirm its episodic nature. We examine the Sloan Digital Sky Survey (SDSS) optical spectrum and estimate the black hole mass to be (8.2 ± 0.3)×10{sup 7} M {sub ☉} from its observed Mg II emission line, and the Eddington ratio to be 0.03. The black hole mass is significantly smaller than for the other reported DDRQ,more » J0935+0204, while the Eddington ratios are comparable. The SDSS spectrum is significantly red-continuum-dominated, suggesting that it is highly obscured with E(B – V){sub host} = 0.70 ± 0.16 mag. This high obscuration further indicates the existence of a large quantity of dust and gas along the line of sight, which may have a key role in triggering the recurrent jet activity in such objects.« less

X-RAYS FROM A RADIO-LOUD COMPACT BROAD ABSORPTION LINE QUASAR 1045+352 AND THE NATURE OF OUTFLOWS IN RADIO-LOUD BROAD ABSORPTION LINE QUASARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunert-Bajraszewska, Magdalena; Katarzynski, Krzysztof; Siemiginowska, Aneta

2009-11-10

We present new results on X-ray properties of radio-loud broad absorption line (BAL) quasars and focus on broadband spectral properties of a high-ionization BAL (HiBAL) compact steep spectrum (CSS) radio-loud quasar 1045+352. This HiBAL quasar has a very complex radio morphology indicating either strong interactions between a radio jet and the surrounding interstellar medium or a possible re-start of the jet activity. We detected 1045+352 quasar in a short 5 ksec Chandra ACIS-S observation. We applied theoretical models to explain spectral energy distribution of 1045+352 and argue that non-thermal, inverse-Compton (IC) emission from the innermost parts of the radio jetmore » can account for a large fraction of the observed X-ray emission. In our analysis, we also consider a scenario in which the observed X-ray emission from radio-loud BAL quasars can be a sum of IC jet X-ray emission and optically thin corona X-ray emission. We compiled a sample of radio-loud BAL quasars that were observed in X-rays to date and report no correlation between their X-ray and radio luminosity. However, the radio-loud BAL quasars show a large range of X-ray luminosities and absorption columns. This is consistent with the results obtained earlier for radio-quiet BAL quasars and may indicate an orientation effect in BAL quasars or more complex dependence between X-ray emission, radio emission, and an orientation based on the radio morphology.« less

When all else fails: 21st century Amateur Radio as an emergency communications medium.

PubMed

Nollet, Kenneth E; Ohto, Hitoshi

2013-12-01

Twenty-first century demand for radio spectrum continues to increase with the explosive growth of wireless devices, but authorities reserve slices of the spectrum for licensed Amateur Radio operators, recognizing their value to the public, particularly with respect to providing emergency communications. Blood banking and transfusion medicine are among the specialties that should also recognize the value of Amateur Radio as an emergency communications medium, because blood collection, testing, processing, storage, and transfusion are life-saving activities that in modern times can be separated by considerable distance. Copyright © 2013 Elsevier Ltd. All rights reserved.

On the Nature of Part-Time Radio Pulsars

NASA Astrophysics Data System (ADS)

Li, Xiang-Dong

2006-08-01

The recent discovery of rotating radio transients and the quasi-periodicity of pulsar activity in the radio pulsar PSR B1931+24 has challenged the conventional theory of radio pulsar emission. Here we suggest that these phenomena could be due to the interaction between the neutron star magnetosphere and the surrounding debris disk. The pattern of pulsar emission depends on whether the disk can penetrate the light cylinder and efficiently quench the processes of particle production and acceleration inside the magnetospheric gap. A precessing disk may naturally account for the switch-on/off behavior in PSR B1931+24.

Occultations of Astrophysical Radio Sources as Probes of Planetary Environments: A Case Study of Jupiter and Possible Applications to Exoplanets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Withers, Paul; Vogt, Marissa F.

Properties of planetary atmospheres, ionospheres, and magnetospheres are difficult to measure from Earth. Radio occultations are a common method for measuring these properties, but they traditionally rely on radio transmissions from a spacecraft near the planet. Here, we explore whether occultations of radio emissions from a distant astrophysical radio source can be used to measure magnetic field strength, plasma density, and neutral density around planets. In a theoretical case study of Jupiter, we find that significant changes in polarization angle due to Faraday rotation occur for radio signals that pass within 10 Jupiter radii of the planet and that significantmore » changes in frequency and power occur from radio signals that pass through the neutral atmosphere. There are sufficient candidate radio sources, such as pulsars, active galactic nuclei, and masers, that occultations are likely to occur at least once per year. For pulsars, time delays in the arrival of their emitted pulses can be used to measure plasma density. Exoplanets, whose physical properties are very challenging to observe, may also occult distant astrophysical radio sources, such as their parent stars.« less

Long-term radio and X-ray evolution of the tidal disruption event ASASSN-14li

NASA Astrophysics Data System (ADS)

Bright, J. S.; Fender, R. P.; Motta, S. E.; Mooley, K.; Perrott, Y. C.; van Velzen, S.; Carey, S.; Hickish, J.; Razavi-Ghods, N.; Titterington, D.; Scott, P.; Grainge, K.; Scaife, A.; Cantwell, T.; Rumsey, C.

2018-04-01

We report on late time radio and X-ray observations of the tidal disruption event candidate ASASSN-14li, covering the first 1000 d of the decay phase. For the first ˜200 d the radio and X-ray emission fade in concert. This phase is better fitted by an exponential decay at X-ray wavelengths, while the radio emission is well described by either an exponential or the canonical t-5/3 decay assumed for tidal disruption events. The correlation between radio and X-ray emission during this period can be fitted as L_R∝ L_X^{1.9± 0.2}. After 400 d the radio emission at 15.5 GHz has reached a plateau level of 244 ± 8 μJy which it maintains for at least the next 600 d, while the X-ray emission continues to fade exponentially. This steady level of radio emission is likely due to relic radio lobes from the weak AGN-like activity implied by historical radio observations. We note that while most existing models are based upon the evolution of ejecta which are decoupled from the central black hole, the radio-X-ray correlation during the declining phase is also consistent with core-jet emission coupled to a radiatively efficient accretion flow.

Radio imaging of the very-high-energy gamma-ray emission region in the central engine of a radio galaxy.

PubMed

Acciari, V A; Aliu, E; Arlen, T; Bautista, M; Beilicke, M; Benbow, W; Bradbury, S M; Buckley, J H; Bugaev, V; Butt, Y; Byrum, K; Cannon, A; Celik, O; Cesarini, A; Chow, Y C; Ciupik, L; Cogan, P; Cui, W; Dickherber, R; Fegan, S J; Finley, J P; Fortin, P; Fortson, L; Furniss, A; Gall, D; Gillanders, G H; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, P; Karlsson, N; Kieda, D; Kildea, J; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; LeBohec, S; Maier, G; McCann, A; McCutcheon, M; Millis, J; Moriarty, P; Ong, R A; Otte, A N; Pandel, D; Perkins, J S; Petry, D; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Roache, E; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Swordy, S P; Theiling, M; Toner, J A; Varlotta, A; Vincent, S; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Williams, D A; Wissel, S; Wood, M; Walker, R C; Davies, F; Hardee, P E; Junor, W; Ly, C; Aharonian, F; Akhperjanian, A G; Anton, G; Barres de Almeida, U; Bazer-Bachi, A R; Becherini, Y; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Borrel, V; Brucker, J; Brun, F; Brun, P; Bühler, R; Bulik, T; Büsching, I; Boutelier, T; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L-M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Füssling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göhring, D; Hauser, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kendziorra, E; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Keogh, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Lamanna, G; Lenain, J-P; Lohse, T; Marandon, V; Martin, J M; Martineau-Huynh, O; Marcowith, A; Maurin, D; McComb, T J L; Medina, M C; Moderski, R; Moulin, E; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; de Oña Wilhelmi, E; Orford, K J; Ostrowski, M; Panter, M; Paz Arribas, M; Pedaletti, G; Pelletier, G; Petrucci, P-O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schröder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Spangler, D; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Superina, G; Szostek, A; Tam, P H; Tavernet, J-P; Terrier, R; Tibolla, O; Tluczykont, M; van Eldik, C; Vasileiadis, G; Venter, C; Venter, L; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A; Anderhub, H; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Balestra, S; Barrio, J A; Bastieri, D; Becerra González, J; Becker, J K; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Bock, R K; Bonnoli, G; Bordas, P; Borla Tridon, D; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Britvitch, I; Camara, M; Carmona, E; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Curtef, V; Dazzi, F; De Angelis, A; De Cea del Pozo, E; Delgado Mendez, C; De los Reyes, R; De Lotto, B; De Maria, M; De Sabata, F; Dominguez, A; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; García López, R J; Garczarczyk, M; Gaug, M; Goebel, F; Hadasch, D; Hayashida, M; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hsu, C C; Jogler, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Oya, I; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Prada, F; Prandini, E; Puchades, N; Reichardt, I; Rhode, W; Ribó, M; Rico, J; Rissi, M; Robert, A; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sanchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schweizer, T; Shayduk, M; Shore, S N; Sidro, N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Stamerra, A; Stark, L S; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Torres, D F; Turini, N; Vankov, H; Wagner, R M; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J

2009-07-24

The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.

Crowd-Sourced Radio Science at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Fry, C. D.; McTernan, J. K.; Suggs, R. M.; Rawlins, L.; Krause, L. H.; Gallagher, D. L.; Adams, M. L.

2018-01-01

August 21, 2017 provided a unique opportunity to investigate the effects of the total solar eclipse on high frequency (HF) radio propagation and ionospheric variability. In Marshall Space Flight Center's partnership with the US Space and Rocket Center (USSRC) and Austin Peay State University (APSU), we engaged citizen scientists and students in an investigation of the effects of an eclipse on the mid-latitude ionosphere. Activities included fieldwork and station-based data collection of HF Amateur Radio frequency bands and VLF radio waves before, during, and after the eclipse to build a continuous record of changing propagation conditions as the moon's shadow marched across the United States. Post-eclipse radio propagation analysis provided insights into ionospheric variability due to the eclipse.

THE LOW-FREQUENCY RADIO CATALOG OF FLAT-SPECTRUM SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; Giroletti, M.; D'Abrusco, R.

A well known property of the γ-ray sources detected by Cos-B in the 1970s, by the Compton Gamma-Ray Observatory in the 1990s, and recently by the Fermi observations is the presence of radio counterparts, particularly for those associated with extragalactic objects. This observational evidence is the basis of the radio-γ-ray connection established for the class of active galactic nuclei known as blazars. In particular, the main spectral property of the radio counterparts associated with γ-ray blazars is that they show a flat spectrum in the GHz frequency range. Our recent analysis dedicated to search blazar-like candidates as potential counterparts formore » the unidentified γ-ray sources allowed us to extend the radio-γ-ray connection in the MHz regime. We also showed that blazars below 1 GHz maintain flat radio spectra. Thus, on the basis of these new results, we assembled a low-frequency radio catalog of flat-spectrum sources built by combining the radio observations of the Westerbork Northern Sky Survey and of the Westerbork in the southern hemisphere catalog with those of the NRAO Very Large Array Sky survey (NVSS). This could be used in the future to search for new, unknown blazar-like counterparts of γ-ray sources. First, we found NVSS counterparts of Westerbork Synthesis Radio Telescope radio sources, and then we selected flat-spectrum radio sources according to a new spectral criterion, specifically defined for radio observations performed below 1 GHz. We also described the main properties of the catalog listing 28,358 radio sources and their logN-logS distributions. Finally, a comparison with the Green Bank 6 cm radio source catalog was performed to investigate the spectral shape of the low-frequency flat-spectrum radio sources at higher frequencies.« less

Observatories and Telescopes of Modern Times

NASA Astrophysics Data System (ADS)

Leverington, David

2016-11-01

Preface; Part I. Optical Observatories: 1. Palomar Mountain Observatory; 2. The United States Optical Observatory; 3. From the Next Generation Telescope to Gemini and SOAR; 4. Competing primary mirror designs; 5. Active optics, adaptive optics and other technical innovations; 6. European Northern Observatory and Calar Alto; 7. European Southern Observatory; 8. Mauna Kea Observatory; 9. Australian optical observatories; 10. Mount Hopkins' Whipple Observatory and the MMT; 11. Apache Point Observatory; 12. Carnegie Southern Observatory (Las Campanas); 13. Mount Graham International Optical Observatory; 14. Modern optical interferometers; 15. Solar observatories; Part II. Radio Observatories: 16. Australian radio observatories; 17. Cambridge Mullard Radio Observatory; 18. Jodrell Bank; 19. Early radio observatories away from the Australian-British axis; 20. The American National Radio Astronomy Observatory; 21. Owens Valley and Mauna Kea; 22. Further North and Central American observatories; 23. Further European and Asian radio observatories; 24. ALMA and the South Pole; Name index; Optical observatory and telescope index; Radio observatory and telescope index; General index.

The new 64m Sardinia Radio Telescope and VLBI facilities in Italy

NASA Astrophysics Data System (ADS)

Giovannini, Gabriele; Feretti, Luigina; Prandoni, Isabella; Giroletti, Marcello

2015-08-01

The Sardinia Radio Telescope (SRT) is a new major radio astronomical facility available in Italy for single dish and interferometric observations. It represents a flexible instrument for Radio Astronomy, Geodynamical studies and Space Science, either in single dish or VLBI mode. The SRT combines a 64m steerable collecting area, one of the largest all over the World with state-of-the-art technology (including an active surface) to enable high efficiency observations up to the 3-mm band.This new radio telescope together with the two 32m antennas in Noto and Medicina can be used for VLBI observations on a national basis (VLBIT). Data can be correlated in a short time (in real time soon) thanks to fiber-optics connection among the radio telescopes and the software correlator installed at the Radio Astronomy Institute in Bologna (IRA/INAF). In the poster I will present capabilities of the SRT telescope as well as the VLBIT project and I will shortly discuss the scientific prospects of the VLBIT.

Radio Source Morphology: 'nature or nuture'?

NASA Astrophysics Data System (ADS)

Banfield, Julie; Emonts, Bjorn; O'Sullivan, Shane

2012-10-01

Radio sources, emanating from supermassive black-holes in the centres of active galaxies, display a large variety of morphological properties. It is a long-standing debate to what extent the differences between various types of radio sources are due to intrinsic properties of the central engine (`nature') or due to the properties of the interstellar medium that surrounds the central engine and host galaxy (`nurture'). Settling this `nature vs. nurture' debate for nearby radio galaxies, which can be studied in great detail, is vital for understanding the properties and evolution of radio galaxies throughout the Universe. We propose to observe the radio galaxy NGC 612 where previous observations have detected the presence of a large-scale HI bridge between the host galaxy and a nearby galaxy NGC 619. We request a total of 13 hrs in the 750m array-configuration to determine whether or not the 100 kpc-scale radio source morphology is directly related to the intergalactic distribution of neutral hydrogen gas.

H I absorption in nearby compact radio galaxies

NASA Astrophysics Data System (ADS)

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 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak optical depths (3-87 per cent). Of the detections, 71 per cent exhibit asymmetric, broad (ΔvFWHM > 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.

Extreme Radio Flares and Associated X-Ray Variability from Young Stellar Objects in the Orion Nebula Cluster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forbrich, Jan; Reid, Mark J.; Wolk, Scott J.

Young stellar objects are known to exhibit strong radio variability on timescales of weeks to months, and a few reports have documented extreme radio flares with at least an order of magnitude change in flux density on timescales of hours to days. However, there have been few constraints on the occurrence rate of such radio flares or on the correlation with pre-main sequence X-ray flares, although such correlations are known for the Sun and nearby active stars. Here we report simultaneous deep VLA radio and Chandra X-ray observations of the Orion Nebula Cluster, targeting hundreds of sources to look formore » the occurrence rate of extreme radio variability and potential correlation with the most extreme X-ray variability. We identify 13 radio sources with extreme radio variability, with some showing an order of magnitude change in flux density in less than 30 minutes. All of these sources show X-ray emission and variability, but we find clear correlations with extreme radio flaring only on timescales <1 hr. Strong X-ray variability does not predict the extreme radio sources and vice versa. Radio flares thus provide us with a new perspective on high-energy processes in YSOs and the irradiation of their protoplanetary disks. Finally, our results highlight implications for interferometric imaging of sources violating the constant-sky assumption.« less

Galaxy-wide radio-induced feedback in a radio-quiet quasar

NASA Astrophysics Data System (ADS)

Villar-Martín, M.; Emonts, B.; Cabrera Lavers, A.; Tadhunter, C.; Mukherjee, D.; Humphrey, A.; Rodríguez Zaurín, J.; Ramos Almeida, C.; Pérez Torres, M.; Bessiere, P.

2017-12-01

We report the discovery of a radio-quiet type 2 quasar (SDSS J165315.06+234943.0 nicknamed the 'Beetle' at z = 0.103) with unambiguous evidence for active galactic nucleus (AGN) radio-induced feedback acting across a total extension of ∼46 kpc and up to ∼26 kpc from the AGN. To the best of our knowledge, this is the first radio-quiet system where radio-induced feedback has been securely identified at ≫several kpc from the AGN. The morphological, ionization and kinematic properties of the extended ionized gas are correlated with the radio structures. We find along the radio axis (a) enhancement of the optical line emission at the location of the radio hotspots (b) turbulent gas kinematics (FWHM ∼ 380-470 km s-1) across the entire spatial range circumscribed by them (c) ionization minima for the turbulent gas at the location of the hot spots, (d) high temperature Te ≳ 1.9 × 104 K at the NE hotspot. Turbulent gas is also found far from the radio axis, ∼25 kpc in the perpendicular direction. We propose a scenario in which the radio structures have perforated the interstellar medium of the galaxy and escaped into the circumgalactic medium. While advancing, they have interacted with in situ gas modifying its properties. Our results show that jets of modest power can be the dominant feedback mechanism acting across huge volumes in radio-quiet systems, including highly accreting luminous AGNs, where radiative mode feedback may be expected.

Radio and X-ray structure of Centaurus A

NASA Technical Reports Server (NTRS)

Feigelson, E. D.

1982-01-01

Recent studies of the nearby radio galaxy Centaurus A with the Very Large Array and the Einstein X-Ray Observatory reveal complex radio and X-ray structures. A prominent one-sided jet comprised of resolved knots located 0.2-6 kpc from the nucleus is seen in both radio and X-rays. The X-ray emission is probably synchrotron, requiring in situ reacceleration up to about ten million. Inverse Compton emission is not a likely explanation though a thermal model in which the nucleus ejects dense 100,000 solar mass clouds cannot be excluded. An elongated X-ray region is also found near the 'middle' radio lobe and optical HII regions about 30 kpc NE of the nucleus. Conditions around the active nucleus, the absence of X-rays from the inner radio lobes, and X-ray evidence for a hot interstellar medium are briefly discussed

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1991-01-01

This quarterly reports on space communications, radio navigation, radio science, and ground based radio and radar astronomy in connection with the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and in operations. Also included is standards activity at JPL for space data and information systems and DSN work. Specific areas of research are: Tracking and ground based navigation; Spacecraft and ground communications; Station control and system technology; DSN Systems Implementation; and DSN Operations.

FPGA applications for single dish activity at Medicina radio telescopes

NASA Astrophysics Data System (ADS)

Bartolini, M.; Naldi, G.; Mattana, A.; Maccaferri, A.; De Biaggi, M.

FPGA technologies are gaining major attention in the recent years in the field of radio astronomy. At Medicina radio telescopes, FPGAs have been used in the last ten years for a number of purposes and in this article we will take into exam the applications developed and installed for the Medicina Single Dish 32m Antenna: these range from high performance digital signal processing to instrument control developed on top of smaller FPGAs.

Health promoting community radio in rural Bali: an impact evaluation.

PubMed

Waters, D; James, R; Darby, J

2011-01-01

This article reports and discusses the process and key recommendations of an evaluation of a community oriented radio station in a rural village in Bali, Indonesia. Community development and health promotion strategies were adopted with the purpose of positively impacting the health and social needs of the local community. The essential element of participation in communication for development was extended to the choice of an evaluation methodology that facilitated community empowerment. The Most Significant Change method was utilised to interview 74 participants (combination of individual interview and focus groups) and to provide the basis for the community itself to identify what it considered to be significant change brought about by the on-air and off-air interventions delivered by the radio station. The 2007 study found that, in contrast to the findings of a needs assessment in 2004, the community now largely valued the input of the radio station with community members stating they were 'very proud of the radio station'. Changes in community perceptions are considered attributable to the radio station adopting a health promotion/community development approach to a combination of on-air programming to support off-air activities within the community. The radio station is in a valuable position to continue making a positive contribution to the village of Tulikup and to the wider region of Bali. Heartline Bali FM made a positive impact on the quality of life of local people through a combination of strategically designed on- and off-air activities based on a community development and community participation approach to radio programming. Most Significant Change evaluation extended and strengthened the participatory dynamic of the 3 year project.

A Search for FRB 121102-like Persistent Radio-luminous Sources—Candidates and Implications for the FRB Rate and Searches

NASA Astrophysics Data System (ADS)

Ofek, Eran O.

2017-09-01

The localization of the repeating fast radio burst (FRB), FRB 121102, suggests that it is associated with a persistent radio-luminous compact source in the FRB host galaxy. Using the FIRST radio catalog, I present a search for luminous persistent sources in nearby galaxies, with radio luminosities > 10 % of the FRB 121102 persistent source luminosity. The galaxy sample contains about 30% of the total galaxy g-band luminosity within < 108 Mpc, in a footprint of 10,600 deg2. After rejecting sources likely due to active galactic nuclei activity or background sources, I am left with 11 candidates that are presumably associated with galactic disks or star-formation regions. At least some of these candidates are likely to be due to chance alignment. In addition, I find 85 sources within 1\\prime\\prime of galactic nuclei. Assuming that the radio persistent sources are not related to galactic nuclei and that they follow the galaxy g-band light, the 11 sources imply a 95% confidence upper limit on the space density of luminous persistent sources of ≲ 5× {10}-5 Mpc-3, and that at any given time only a small fraction of galaxies host a radio-luminous persistent source (≲ {10}-3 {L}* -1). Assuming a persistent source lifetime of 100 years, this implies a birth rate of ≲ 5× {10}-7 yr-1 Mpc-3. Given the FRB volumetric rate, and assuming that all FRBs repeat and are associated with persistent radio sources, this sets a lower limit on the rate of FRB events per persistent source of ≳ 0.8 yr-1. I argue that these 11 candidates are good targets for FRB searches and I estimate the FRB event rate from these candidates.

Tracking system analytic calibration activities for the Mariner Mars 1971 mission

NASA Technical Reports Server (NTRS)

Madrid, G. A.; Chao, C. C.; Fliegel, H. F.; Leavitt, R. K.; Mottinger, N. A.; Winn, F. B.; Wimberly, R. N.; Yip, K. B.; Zielenbach, J. W.

1974-01-01

Data covering various planning aspects of Mariner Mars 1971 mission are summarized. Data cover calibrating procedures for tracking stations, radio signal propagation in the troposphere, effects of charged particles on radio transmission, orbit calculation, and data smoothing.

47 CFR 74.634 - Remote control operation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... control system must be designed, installed, and protected so that the transmitter can only be activated or... ensure proper operation. (3) The remote control system must be designed to prevent inadvertent...

47 CFR 74.634 - Remote control operation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... control system must be designed, installed, and protected so that the transmitter can only be activated or... ensure proper operation. (3) The remote control system must be designed to prevent inadvertent...

47 CFR 74.634 - Remote control operation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... control system must be designed, installed, and protected so that the transmitter can only be activated or... ensure proper operation. (3) The remote control system must be designed to prevent inadvertent...

47 CFR 74.634 - Remote control operation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... control system must be designed, installed, and protected so that the transmitter can only be activated or... ensure proper operation. (3) The remote control system must be designed to prevent inadvertent...

47 CFR 74.634 - Remote control operation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... control system must be designed, installed, and protected so that the transmitter can only be activated or... ensure proper operation. (3) The remote control system must be designed to prevent inadvertent...

Waves in Space Plasmas (WISP)

NASA Technical Reports Server (NTRS)

Calvert, Wynne

1994-01-01

Activities under this project have included participation in the Waves in Space Plasmas (WISP) program, a study of the data processing requirements for WISP, and theoretical studies of radio sounding, ducting, and magnetoionic theory. An analysis of radio sounding in the magnetosphere was prepared.

The Spectrum Landscape: Prospects for Terrestrial Radio Astronomy

NASA Astrophysics Data System (ADS)

Liszt, Harvey Steven

2018-01-01

Radio astronomers work within broad constraints imposed by commercial and other non-astronomical uses of the radio spectrum, somewhat modified to accommodate astronomy’s particular needs through the provision of radio quiet zones, radio frequency allocations, coordination agreements and other devices of spectrum management. As radio astronomers increase the instantaneous bandwidth, frequency coverage and sensitivity of their instruments, these external constraints, and not the limitations of their own instruments, will increasingly be the greatest obstacles to radio astronomy’s ability to observe the cosmos from the surface of the Earth. Therefore, prospects for future radio astronomy operations are contingent on situational awareness and planning for the impact of non-astronomical uses of the radio frequency spectrum. New radio astronomy instruments will have to incorporate adaptive reactions to external developments, and radio astronomers should be encouraged to think in untraditional ways. Increased attention to spectrum management is one of these. In this talk I’ll recap some recent developments such as the proliferation of 76 – 81 GHz car radar and orbiting earth-mapping radars, either of which can burn out a radio astronomy receiver. I’ll summarize present trends for non-astronomical radio spectrum use that will be coming to fruition in the next decade or so, categorized into terrestrial fixed and mobile, airborne and space-borne uses, sub-divided by waveband from the cm to the sub-mm. I’ll discuss how they will impact terrestrial radio astronomy and the various ways in which radio astronomy should be prepared to react. Protective developments must occur both within radio astronomy’s own domain – designing, siting and constructing its instruments and mitigating unavoidable RFI – and facing outward toward the community of other spectrum users. Engagement with spectrum management is no panacea but it is an important means, and perhaps the only means, by which radio astronomy can take an active role in shaping its terrestrial environment.

Radio Counterparts of Compact Binary Mergers Detectable in Gravitational Waves: A Simulation for an Optimized Survey

NASA Astrophysics Data System (ADS)

Hotokezaka, K.; Nissanke, S.; Hallinan, G.; Lazio, T. J. W.; Nakar, E.; Piran, T.

2016-11-01

Mergers of binary neutron stars and black hole-neutron star binaries produce gravitational-wave (GW) emission and outflows with significant kinetic energies. These outflows result in radio emissions through synchrotron radiation. We explore the detectability of these synchrotron-generated radio signals by follow-up observations of GW merger events lacking a detection of electromagnetic counterparts in other wavelengths. We model radio light curves arising from (I) sub-relativistic merger ejecta and (II) ultra-relativistic jets. The former produce radio remnants on timescales of a few years and the latter produce γ-ray bursts in the direction of the jet and orphan-radio afterglows extending over wider angles on timescales of weeks. Based on the derived light curves, we suggest an optimized survey at 1.4 GHz with five epochs separated by a logarithmic time interval. We estimate the detectability of the radio counterparts of simulated GW-merger events to be detected by advanced LIGO and Virgo by current and future radio facilities. The detectable distances for these GW merger events could be as high as 1 Gpc. Around 20%-60% of the long-lasting radio remnants will be detectable in the case of the moderate kinetic energy of 3\\cdot {10}50 erg and a circum-merger density of 0.1 {{cm}}-3 or larger, while 5%-20% of the orphan-radio afterglows with kinetic energy of 1048 erg will be detectable. The detection likelihood increases if one focuses on the well-localizable GW events. We discuss the background noise due to radio fluxes of host galaxies and false positives arising from extragalactic radio transients and variable active galactic nuclei, and we show that the quiet radio transient sky is of great advantage when searching for the radio counterparts.

A Robust Crowdsourcing-Based Indoor Localization System.

PubMed

Zhou, Baoding; Li, Qingquan; Mao, Qingzhou; Tu, Wei

2017-04-14

WiFi fingerprinting-based indoor localization has been widely used due to its simplicity and can be implemented on the smartphones. The major drawback of WiFi fingerprinting is that the radio map construction is very labor-intensive and time-consuming. Another drawback of WiFi fingerprinting is the Received Signal Strength (RSS) variance problem, caused by environmental changes and device diversity. RSS variance severely degrades the localization accuracy. In this paper, we propose a robust crowdsourcing-based indoor localization system (RCILS). RCILS can automatically construct the radio map using crowdsourcing data collected by smartphones. RCILS abstracts the indoor map as the semantics graph in which the edges are the possible user paths and the vertexes are the location where users may take special activities. RCILS extracts the activity sequence contained in the trajectories by activity detection and pedestrian dead-reckoning. Based on the semantics graph and activity sequence, crowdsourcing trajectories can be located and a radio map is constructed based on the localization results. For the RSS variance problem, RCILS uses the trajectory fingerprint model for indoor localization. During online localization, RCILS obtains an RSS sequence and realizes localization by matching the RSS sequence with the radio map. To evaluate RCILS, we apply RCILS in an office building. Experiment results demonstrate the efficiency and robustness of RCILS.

A Robust Crowdsourcing-Based Indoor Localization System

PubMed Central

Zhou, Baoding; Li, Qingquan; Mao, Qingzhou; Tu, Wei

2017-01-01

WiFi fingerprinting-based indoor localization has been widely used due to its simplicity and can be implemented on the smartphones. The major drawback of WiFi fingerprinting is that the radio map construction is very labor-intensive and time-consuming. Another drawback of WiFi fingerprinting is the Received Signal Strength (RSS) variance problem, caused by environmental changes and device diversity. RSS variance severely degrades the localization accuracy. In this paper, we propose a robust crowdsourcing-based indoor localization system (RCILS). RCILS can automatically construct the radio map using crowdsourcing data collected by smartphones. RCILS abstracts the indoor map as the semantics graph in which the edges are the possible user paths and the vertexes are the location where users may take special activities. RCILS extracts the activity sequence contained in the trajectories by activity detection and pedestrian dead-reckoning. Based on the semantics graph and activity sequence, crowdsourcing trajectories can be located and a radio map is constructed based on the localization results. For the RSS variance problem, RCILS uses the trajectory fingerprint model for indoor localization. During online localization, RCILS obtains an RSS sequence and realizes localization by matching the RSS sequence with the radio map. To evaluate RCILS, we apply RCILS in an office building. Experiment results demonstrate the efficiency and robustness of RCILS. PMID:28420108

Activities of the International Radio Medical Centre (C.I.R.M.) in Rome during the last five years (1996-2000). Centro Internazionale Radio Medico.

PubMed

Amenta, F; Dauri, A

2001-01-01

This paper reviews medical activity provided from 1996 to 2000 by the International Radio Medical Centre (Centro Internazionale Radio Medico, C.I.R.M.). C.I.R.M. is a non-profit organization headquartered in Rome and providing freely telemedical advice to ships flying of any flag navigating on all seas of the world, to civil airplanes and to small Italian islands. From 1996 to 2000 C.I.R.M. has assisted 4,982 patients, 4,686 of which (94%) on board ships, 85 on airplanes and 206 on small Italian islands. More than 65% of requests of telemedical advice received by C.I.R.M. were from non-Italian ships. This indicates the really international nature of C.I.R.M.'s activity. The largest number of medical requests come from the Atlantic Ocean, followed by the Mediterranean sea, Indian Ocean and Pacific Ocean. In terms of pathologies assisted, accidents took the first place, followed as main pathologies by gastrointestinal disorders, cardiovascular pathologies, respiratory disorders, infectious and parasitic diseases and nervous system complaints. Analysis of the outcome of C.I.R.M.'s medical activity showed that more than 50% of patients assisted were recovered or improved while assisted by the Centre.

Duty-cycle and energetics of remnant radio-loud AGN

NASA Astrophysics Data System (ADS)

Turner, Ross J.

2018-05-01

Deriving the energetics of remnant and restarted active galactic nuclei (AGNs) is much more challenging than for active sources due to the complexity in accurately determining the time since the nucleus switched-off. I resolve this problem using a new approach that combines spectral ageing and dynamical models to tightly constrain the energetics and duty-cycles of dying sources. Fitting the shape of the integrated radio spectrum yields the fraction of the source age the nucleus is active; this, in addition to the flux density, source size, axis ratio, and properties of the host environment, provides a constraint on dynamical models describing the remnant radio source. This technique is used to derive the intrinsic properties of the well-studied remnant radio source B2 0924+30. This object is found to spend 50_{-12}^{+14} Myr in the active phase and a further 28_{-5}^{+6} Myr in the quiescent phase, have a jet kinetic power of 3.6_{-1.7}^{+3.0}× 10^{37} W, and a lobe magnetic field strength below equipartition at the 8σ level. The integrated spectra of restarted and intermittent radio sources are found to yield a `steep-shallow' shape when the previous outburst occurred within 100 Myr. The duty-cycle of B2 0924+30 is hence constrained to be δ < 0.15 by fitting the shortest time to the previous comparable outburst that does not appreciably modify the remnant spectrum. The time-averaged feedback energy imparted by AGNs into their host galaxy environments can in this manner be quantified.

The Search for Stellar Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Villadsen, Jacqueline; Hallinan, Gregg; Monroe, Ryan; Bourke, Stephen; Starburst Program Team

2017-01-01

Coronal mass ejections (CMEs) may dramatically impact habitability and atmospheric composition of planets around magnetically active stars, including young solar analogs and many M dwarfs. Theoretical predictions of such effects are limited by the lack of observations of stellar CMEs. My thesis addresses this gap through a search for the spectral and spatial radio signatures of CMEs on active M dwarfs.Solar CMEs produce radio bursts with a distinctive spectral signature, narrow-band plasma emission that drifts to lower frequency as a CME expands outward. To search for analogous events on nearby stars, I worked on system design, software, and commissioning for the Starburst project, a wideband single-baseline radio interferometry backend dedicated to stellar observations. In addition, I led a survey of nearby active M dwarfs with the Karl G. Jansky Very Large Array (JVLA), detecting 12 bright (>10 mJy) radio bursts in 58 hours. This survey’s ultra-wide bandwidth (0.23-6.0 GHz) dynamic spectroscopy, unprecedented for stellar observations, revealed diverse behavior in the time-frequency plane. Flare star UV Ceti produced complex, luminous events reminiscent of brown dwarf aurorae; AD Leo sustained long-duration, intense, narrow-band "storms"; and YZ CMi emitted a burst with substructure with rapid frequency drift, resembling solar Type III bursts, which are attributed to electrons moving at speeds of order 10% of the speed of light.To search for the spatial signature of CMEs, I led 8.5-GHz observations with the Very Long Baseline Array simultaneous to 24 hours of the JVLA survey. This program detected non-thermal continuum emission from the stars in all epochs, as well as continuum flares on AD Leo and coherent bursts on UV Ceti, enabling measurement of the spatial offset between flaring and quiescent emission.These observations demonstrate the diversity of stellar transients that can be expected in time-domain radio surveys, especially with the advent of large low-frequency radio telescopes. Wide bandwidth radio dynamic spectroscopy, complemented by high-resolution imaging of the radio corona, is a powerful technique for detecting stellar eruptions and characterizing dynamic processes in the stellar corona.

The Search for Stellar Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Villadsen, Jacqueline Rose

2017-05-01

Coronal mass ejections (CMEs) may dramatically impact habitability and atmospheric composition of planets around magnetically active stars, including young solar analogs and many M dwarfs. Theoretical predictions of such effects are limited by the lack of observations of stellar CMEs. This thesis addresses this gap through a search for the spectral and spatial radio signatures of CMEs on active M dwarfs. Solar CMEs produce radio bursts with a distinctive spectral signature, narrow-band plasma emission that drifts to lower frequency as a CME expands outward. To search for analogous events on nearby stars, I worked on system design, software, and commissioning for the Starburst project, a wideband single-baseline radio interferometry backend dedicated to stellar observations. In addition, I led a survey of nearby active M dwarfs with the Karl G. Jansky Very Large Array (VLA), detecting coherent radio bursts in 13 out of 23 epochs, over a total of 58 hours. This survey's ultra-wide bandwidth (0.23-6.0 GHz) dynamic spectroscopy, unprecedented for stellar observations, revealed diverse behavior in the time-frequency plane. Flare star UV Ceti produced complex, luminous events reminiscent of brown dwarf aurorae; AD Leo sustained long-duration, intense, narrow-band "storms"; and YZ CMi emitted a burst with substructure with rapid frequency drift, resembling solar Type III bursts, which are attributed to electrons moving at speeds of order 10% of the speed of light. To search for the spatial signature of CMEs, I led 8.5-GHz observations with the Very Long Baseline Array simultaneous to 24 hours of the VLA survey. This program detected non-thermal continuum emission from the stars in all epochs, as well as continuum flares on AD Leo and coherent bursts on UV Ceti, enabling measurement of the spatial offset between flaring and quiescent emission. These observations demonstrate the diversity of stellar transients that can be expected in time-domain radio surveys, especially with the advent of large low-frequency radio telescopes. Wide bandwidth radio dynamic spectroscopy, complemented by high-resolution imaging of the radio corona, is a powerful technique for detecting stellar eruptions and characterizing dynamic processes in the stellar corona.

Effects of different radio-opacifying agents on physicochemical and biological properties of a novel root-end filling material

PubMed Central

Lü, Xiao-Ying; Liu, Gen-Di

2018-01-01

Background/Purpose Radio-opacity is an essential attribute of ideal root-end filling materials because it is important for clinicians to observe root canal filling and to facilitate the follow-up instructions. The novel root-end filling material (NRFM) has good cytocompatibility and physicochemical properties but low intrinsic radio-opacity value. To improve its radio-opacity value, three novel radio-opaque root-end filling materials (NRRFMs) were developed by adding barium sulphate (NRFM-Ba), bismuth trioxide (NRFM-Bi) and zirconium dioxide (NRFM-Zr) to NRFM, respectively. The purpose of this study was to identify the suitable radio-opacifier for NRFM through evaluating their physicochemical and biological properties, in comparison with NRFM and glass ionomer cement (GIC). Methods NRRFMs were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectrophotometry (FTIR). Physicochemical properties including setting time, compressive strength, porosity, pH variation, solubility, washout resistance, contact angle and radiopacity were investigated. Cytocompatibility of both freshly mixed and set NRRFMs was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Alkaline phosphatase (ALP) activity assay and alizarin red staining were used to investigate the osteogenic differentiation potential of NRFM-Zr. Data were analyzed using two-way ANOVA (pH variation, solubility and ALP activity) and one-way ANOVA (for the other variables). Results (1) NRRFMs were primarily composed of hydroxyapatite, calcium carboxylate salt and the corresponding radio-opacity agents (barium sulphate, bismuth trioxide or zirconium dioxide). (2) Besides similar physicochemical properties in terms of setting time, pH variation, solubility, washout resistance and contact angle to NRFM, NRFM-Bi and NRFM-Zr exhibited lower porosity and greater compressive strength after being set for 7 days and their radio-opacity were greater than the 3 mm aluminium thickness specified in ISO 6876 (2001). (3) MTT assay revealed that freshly mixed and set NRFM-Zr presented better cell viability than NRFM-Ba and NRFM-Bi at 24 hours and 48 hours (P<0.05). (4) NRFM-Zr significantly enhanced ALP activity and calcium formation of human osteoblast-like Saos-2 cells when compared with negative group and GIC (P<0.05). Conclusion NRFM-Zr presents desirable physicochemical and biological properties, thus zirconium dioxide may be a suitable radio-opacifier for NRFM. PMID:29420559

Effects of different radio-opacifying agents on physicochemical and biological properties of a novel root-end filling material.

PubMed

Chen, Yao-Zhong; Lü, Xiao-Ying; Liu, Gen-Di

2018-01-01

Radio-opacity is an essential attribute of ideal root-end filling materials because it is important for clinicians to observe root canal filling and to facilitate the follow-up instructions. The novel root-end filling material (NRFM) has good cytocompatibility and physicochemical properties but low intrinsic radio-opacity value. To improve its radio-opacity value, three novel radio-opaque root-end filling materials (NRRFMs) were developed by adding barium sulphate (NRFM-Ba), bismuth trioxide (NRFM-Bi) and zirconium dioxide (NRFM-Zr) to NRFM, respectively. The purpose of this study was to identify the suitable radio-opacifier for NRFM through evaluating their physicochemical and biological properties, in comparison with NRFM and glass ionomer cement (GIC). NRRFMs were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectrophotometry (FTIR). Physicochemical properties including setting time, compressive strength, porosity, pH variation, solubility, washout resistance, contact angle and radiopacity were investigated. Cytocompatibility of both freshly mixed and set NRRFMs was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Alkaline phosphatase (ALP) activity assay and alizarin red staining were used to investigate the osteogenic differentiation potential of NRFM-Zr. Data were analyzed using two-way ANOVA (pH variation, solubility and ALP activity) and one-way ANOVA (for the other variables). (1) NRRFMs were primarily composed of hydroxyapatite, calcium carboxylate salt and the corresponding radio-opacity agents (barium sulphate, bismuth trioxide or zirconium dioxide). (2) Besides similar physicochemical properties in terms of setting time, pH variation, solubility, washout resistance and contact angle to NRFM, NRFM-Bi and NRFM-Zr exhibited lower porosity and greater compressive strength after being set for 7 days and their radio-opacity were greater than the 3 mm aluminium thickness specified in ISO 6876 (2001). (3) MTT assay revealed that freshly mixed and set NRFM-Zr presented better cell viability than NRFM-Ba and NRFM-Bi at 24 hours and 48 hours (P<0.05). (4) NRFM-Zr significantly enhanced ALP activity and calcium formation of human osteoblast-like Saos-2 cells when compared with negative group and GIC (P<0.05). NRFM-Zr presents desirable physicochemical and biological properties, thus zirconium dioxide may be a suitable radio-opacifier for NRFM.

Remote Observational Techniques in Education

NASA Astrophysics Data System (ADS)

Thieman, J.; Mayo, L.

2002-09-01

The ability to observe celestial objects remotely is making a major impact into classroom access to astronomical instrumentation previously impossible to encorporate into curriculum. Two programs, Radio Jove and Telescopes In Education have made important contributions in this field. Radio JOVE is an interactive, hands-on, educational activity for learning the scientific method through the medium of radio observations of Jupiter, the Sun, and the galactic radio background. Students build radio receivers from relatively inexpensive non-profit kits (about \\$125 plus shipping) and use them to record data, analyze the data, and share the results with others. Alternatively, for no cost, the students can record and analyze data from remote radio receivers connected to the web. The projects are useful adjuncts to activities in optical observing since students should recognize that we learn about the universe through more than just the optical spectrum. The projects are mini-electronics courses and also teach about charged particles and magnetic fields. The Radio JOVE web site (http://radiojove.gsfc.nasa.gov) should be consulted for further information. The NASA-sponsored Telescopes In Education (TIE) network (http://tie.jpl.nasa.gov) has been wildly successful in engaging the K-12 education community in real-time, hands-on, interactive astronomy activities. Hundreds of schools in the US, Australia, Canada, England, and Japan have participated in the TIE program, remotely controlling the 24-inch telescope at the Mount Wilson Observatory from their classrooms. In recent years, several (approximately 20 to date) other telescopes have been, or are in the process of being, outfitted for remote use as TIE affiliates. These telescopesare integrated seamlessly into one virtual observatory providing the services required to operate this facility, including a scheduling service, tools for data manipulation, an online proposal review environment, an online "Virtual TIE Student Ap J" for publication of results, and access to related educational materials provided by the TIE community.

47 CFR 90.20 - Public Safety Pool.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Safety Pool to operate radio stations for transmission of communications essential to official activities... operate stations for transmission of communications essential for the delivery or rendition of emergency... Public Safety Pool to operate radio stations for transmission of communications, as listed below. When...

47 CFR 95.1105 - Eligibility.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO... health care providers are authorized by rule to operate transmitters in the Wireless Medical Telemetry... authorized health care providers. No entity that is a foreign government or which is active in the capacity...

47 CFR 95.1105 - Eligibility.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO... health care providers are authorized by rule to operate transmitters in the Wireless Medical Telemetry... authorized health care providers. No entity that is a foreign government or which is active in the capacity...

Models of Uranium continuum radio emission

NASA Technical Reports Server (NTRS)

Romig, Joseph H.; Evans, David R.; Sawyer, Constance B.; Schweitzer, Andrea E.; Warwick, James W.

1987-01-01

Uranium continuum radio emission detected by the Voyager 2 Planetary Radio Astronomy experiment during the January 1986 encounter is considered. The continuum emissions comprised four components (equatorial emissions, anomaly emissions, strong nightside emissions, and weak nightside emissions) associated with different sources. The equatorial emissions appeared most prominently during the days before closest approach and extended from 40 kHz or below to about 120 kHz. The anomaly emissions were seen about 12 hours before closest approach and extended to about 250 kHz. The agreement found between Miranda's phase and strong radio emission at 20.4 kHz, just after closest approach, suggests intense dynamic activity on the Miranda L shell.

Giant Low Surface Brightness Galaxies

NASA Astrophysics Data System (ADS)

Mishra, Alka; Kantharia, Nimisha G.; Das, Mousumi

2018-04-01

In this paper, we present radio observations of the giant low surface brightness (LSB) galaxies made using the Giant Metrewave Radio Telescope (GMRT). LSB galaxies are generally large, dark matter dominated spirals that have low star formation efficiencies and large HI gas disks. Their properties suggest that they are less evolved compared to high surface brightness galaxies. We present GMRT emission maps of LSB galaxies with an optically-identified active nucleus. Using our radio data and archival near-infrared (2MASS) and near-ultraviolet (GALEX) data, we studied morphology and star formation efficiencies in these galaxies. All the galaxies show radio continuum emission mostly associated with the centre of the galaxy.

Development of an Automatic Echo-counting Program for HROFFT Spectrograms

NASA Astrophysics Data System (ADS)

Noguchi, Kazuya; Yamamoto, Masa-Yuki

2008-06-01

Radio meteor observations by Ham-band beacon or FM radio broadcasts using “Ham-band Radio meteor Observation Fast Fourier Transform” (HROFFT) an automatic operating software have been performed widely in recent days. Previously, counting of meteor echoes on the spectrograms of radio meteor observation was performed manually by observers. In the present paper, we introduce an automatic meteor echo counting software application. Although output images of the HROFFT contain both the features of meteor echoes and those of various types of noises, a newly developed image processing technique has been applied, resulting in software that enables a useful auto-counting tool. There exists a slight error in the processing on spectrograms when the observation site is affected by many disturbing noises. Nevertheless, comparison between software and manual counting revealed an agreement of almost 90%. Therefore, we can easily obtain a dataset of detection time, duration time, signal strength, and Doppler shift of each meteor echo from the HROFFT spectrograms. Using this software, statistical analyses of meteor activities is based on the results obtained at many Ham-band Radio meteor Observation (HRO) sites throughout the world, resulting in a very useful “standard” for monitoring meteor stream activities in real time.

Jets, arcs, and shocks: NGC 5195 at radio wavelengths

NASA Astrophysics Data System (ADS)

Rampadarath, H.; Soria, R.; Urquhart, R.; Argo, M. K.; Brightman, M.; Lacey, C. K.; Schlegel, E. M.; Beswick, R. J.; Baldi, R. D.; Muxlow, T. W. B.; McHardy, I. M.; Williams, D. R. A.; Dumas, G.

2018-05-01

We studied the nearby, interacting galaxy NGC 5195 (M 51b) in the radio, optical and X-ray bands. We mapped the extended, low-surface-brightness features of its radio-continuum emission; determined the energy content of its complex structure of shock-ionized gas; constrained the current activity level of its supermassive nuclear black hole. In particular, we combined data from the European Very Long Baseline Interferometry Network (˜1-pc scale), from our new e-MERLIN observations (˜10-pc scale), and from the Very Large Array (˜100-1000-pc scale), to obtain a global picture of energy injection in this galaxy. We put an upper limit to the luminosity of the (undetected) flat-spectrum radio core. We find steep-spectrum, extended emission within 10 pc of the nuclear position, consistent with optically thin synchrotron emission from nuclear star formation or from an outflow powered by an active galactic nucleus (AGN). A linear spur of radio emission juts out of the nuclear source towards the kpc-scale arcs (detected in radio, Hα and X-ray bands). From the size, shock velocity, and Balmer line luminosity of the kpc-scale bubble, we estimate that it was inflated by a long-term-average mechanical power ˜3-6 × 1041 erg s-1 over the last 3-6 Myr. This is an order of magnitude more power than can be provided by the current level of star formation, and by the current accretion power of the supermassive black hole. We argue that a jet-inflated bubble scenario associated with previous episodes of AGN activity is the most likely explanation for the kpc-scale structures.

Unveiling the AGN in IC 883: discovery of a parsec-scale radio jet

NASA Astrophysics Data System (ADS)

Romero-Cañizales, C.; Alberdi, A.; Ricci, C.; Arévalo, P.; Pérez-Torres, M. Á.; Conway, J. E.; Beswick, R. J.; Bondi, M.; Muxlow, T. W. B.; Argo, M. K.; Bauer, F. E.; Efstathiou, A.; Herrero-Illana, R.; Mattila, S.; Ryder, S. D.

2017-05-01

IC 883 is a luminous infrared galaxy (LIRG) classified as a starburst-active galactic nucleus (AGN) composite. In a previous study, we detected a low-luminosity AGN (LLAGN) radio candidate. Here, we report on our radio follow-up at three frequencies that provides direct and unequivocal evidence of the AGN activity in IC 883. Our analysis of archival X-ray data, together with the detection of a transient radio source with luminosity typical of bright supernovae, gives further evidence of the ongoing star formation activity, which dominates the energetics of the system. At sub-parsec scales, the radio nucleus has a core-jet morphology with the jet being a newly ejected component showing a subluminal proper motion of 0.6-1 c. The AGN contributes less than 2 per cent of the total IR luminosity of the system. The corresponding Eddington factor is ˜10-3, suggesting this is a low-accretion rate engine, as often found in LLAGNs. However, its high bolometric luminosity (˜1044 erg s-1) agrees better with a normal AGN. This apparent discrepancy may just be an indication of the transition nature of the nucleus from a system dominated by star formation, to an AGN-dominated system. The nucleus has a strongly inverted spectrum and a turnover at ˜4.4 GHz, thus qualifying as a candidate for the least luminous (L5.0 GHz ˜ 6.3 × 1028 erg s-1 Hz-1) and one of the youngest (˜3 × 103 yr) gigahertz-peaked spectrum (GPS) sources. If the GPS origin for the IC 883 nucleus is confirmed, then advanced mergers in the LIRG category are potentially key environments to unveil the evolution of GPS sources into more powerful radio galaxies.

Mpc-scale diffuse radio emission in two massive cool-core clusters of galaxies

NASA Astrophysics Data System (ADS)

Sommer, Martin W.; Basu, Kaustuv; Intema, Huib; Pacaud, Florian; Bonafede, Annalisa; Babul, Arif; Bertoldi, Frank

2017-04-01

Radio haloes are diffuse synchrotron sources on scales of ˜1 Mpc that are found in merging clusters of galaxies, and are believed to be powered by electrons re-accelerated by merger-driven turbulence. We present measurements of extended radio emission on similarly large scales in two clusters of galaxies hosting cool cores: Abell 2390 and Abell 2261. The analysis is based on interferometric imaging with the Karl G. Jansky Very Large Array, Very Large Array and Giant Metrewave Radio Telescope. We present detailed radio images of the targets, subtract the compact emission components and measure the spectral indices for the diffuse components. The radio emission in A2390 extends beyond a known sloshing-like brightness discontinuity, and has a very steep in-band spectral slope at 1.5 GHz that is similar to some known ultrasteep spectrum radio haloes. The diffuse signal in A2261 is more extended than in A2390 but has lower luminosity. X-ray morphological indicators, derived from XMM-Newton X-ray data, place these clusters in the category of relaxed or regular systems, although some asymmetric features that can indicate past minor mergers are seen in the X-ray brightness images. If these two Mpc-scale radio sources are categorized as giant radio haloes, they question the common assumption of radio haloes occurring exclusively in clusters undergoing violent merging activity, in addition to commonly used criteria for distinguishing between radio haloes and minihaloes.

Inverse Compton X-Ray Halos Around High-z Radio Galaxies: A Feedback Mechanism Powered by Far-Infrared Starbursts or the Cosmic Microwave Background?

NASA Technical Reports Server (NTRS)

Small, Ian; Blundell, Katherine M.; Lehmer, B. D.; Alexander, D. M.

2012-01-01

We report the detection of extended X-ray emission around two powerful radio galaxies at z approx. 3.6 (4C 03.24 and 4C 19.71) and use these to investigate the origin of extended, inverse Compton (IC) powered X-ray halos at high redshifts. The halos have X-ray luminosities of L(sub X) approx. 3 x 10(exp 44) erg/s and sizes of approx.60 kpc. Their morphologies are broadly similar to the approx.60 kpc long radio lobes around these galaxies suggesting they are formed from IC scattering by relativistic electrons in the radio lobes, of either cosmic microwave background (CMB) photons or far-infrared photons from the dust-obscured starbursts in these galaxies. These observations double the number of z > 3 radio galaxies with X-ray-detected IC halos. We compare the IC X-ray-to-radio luminosity ratios for the two new detections to the two previously detected z approx. 3.8 radio galaxies. Given the similar redshifts, we would expect comparable X-ray IC luminosities if millimeter photons from the CMB are the dominant seed field for the IC emission (assuming all four galaxies have similar ages and jet powers). Instead we see that the two z approx. 3.6 radio galaxies, which are 4 fainter in the far-infrared than those at z 3.8, also have approx.4x fainter X-ray IC emission. Including data for a further six z > or approx. 2 radio sources with detected IC X-ray halos from the literature, we suggest that in the more compact, majority of radio sources, those with lobe sizes < or approx.100-200 kpc, the bulk of the IC emission may be driven by scattering of locally produced far-infrared photons from luminous, dust-obscured starbursts within these galaxies, rather than millimeter photons from the CMB. The resulting X-ray emission appears sufficient to ionize the gas on approx.100-200 kpc scales around these systems and thus helps form the extended, kinematically quiescent Ly(alpha) emission line halos found around some of these systems. The starburst and active galactic nucleus activity in these galaxies are thus combining to produce an even more effective and widespread "feedback" process, acting on the long-term gas reservoir for the galaxy, than either individually could achieve. If episodic radio activity and co-eval starbursts are common in massive, high-redshift galaxies, then this IC-feedback mechanism may play a role in affecting the star formation histories of the most massive galaxies at the present day.

The case for electron re-acceleration at galaxy cluster shocks

NASA Astrophysics Data System (ADS)

van Weeren, Reinout J.; Andrade-Santos, Felipe; Dawson, William A.; Golovich, Nathan; Lal, Dharam V.; Kang, Hyesung; Ryu, Dongsu; Brìggen, Marcus; Ogrean, Georgiana A.; Forman, William R.; Jones, Christine; Placco, Vinicius M.; Santucci, Rafael M.; Wittman, David; Jee, M. James; Kraft, Ralph P.; Sobral, David; Stroe, Andra; Fogarty, Kevin

2017-01-01

On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio sources have been found1,2 . Also known as radio relics, these regions of diffuse radio emission are thought to trace relativistic electrons in the intracluster plasma accelerated by low-Mach-number shocks generated by cluster-cluster merger events 3 . A long-standing problem is how low-Mach-number shocks can accelerate electrons so efficiently to explain the observed radio relics. Here, we report the discovery of a direct connection between a radio relic and a radio galaxy in the merging galaxy cluster Abell 3411-3412 by combining radio, X-ray and optical observations. This discovery indicates that fossil relativistic electrons from active galactic nuclei are re-accelerated at cluster shocks. It also implies that radio galaxies play an important role in governing the non-thermal component of the intracluster medium in merging clusters.

The case for electron re-acceleration at galaxy cluster shocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Weeren, Reinout J.; Andrade-Santos, Felipe; Dawson, William A.

On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio sources have been found. Also known as radio relics, these regions of diffuse radio emission are thought to trace relativistic electrons in the intracluster plasma accelerated by low-Mach-number shocks generated by cluster–cluster merger events. A long-standing problem is how low-Mach-number shocks can acceleratemore » electrons so efficiently to explain the observed radio relics. Here, we report the discovery of a direct connection between a radio relic and a radio galaxy in the merging galaxy cluster Abell 3411–3412 by combining radio, X-ray and optical observations. This discovery indicates that fossil relativistic electrons from active galactic nuclei are re-accelerated at cluster shocks. Lastly, it also implies that radio galaxies play an important role in governing the non-thermal component of the intracluster medium in merging clusters.« less

The case for electron re-acceleration at galaxy cluster shocks

DOE PAGES

van Weeren, Reinout J.; Andrade-Santos, Felipe; Dawson, William A.; ...

2017-01-04

On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio sources have been found. Also known as radio relics, these regions of diffuse radio emission are thought to trace relativistic electrons in the intracluster plasma accelerated by low-Mach-number shocks generated by cluster–cluster merger events. A long-standing problem is how low-Mach-number shocks can acceleratemore » electrons so efficiently to explain the observed radio relics. Here, we report the discovery of a direct connection between a radio relic and a radio galaxy in the merging galaxy cluster Abell 3411–3412 by combining radio, X-ray and optical observations. This discovery indicates that fossil relativistic electrons from active galactic nuclei are re-accelerated at cluster shocks. Lastly, it also implies that radio galaxies play an important role in governing the non-thermal component of the intracluster medium in merging clusters.« less

Constraints on submicrojansky radio number counts based on evolving VLA-COSMOS luminosity functions

NASA Astrophysics Data System (ADS)

Novak, M.; Smolčić, V.; Schinnerer, E.; Zamorani, G.; Delvecchio, I.; Bondi, M.; Delhaize, J.

2018-06-01

We present an investigation of radio luminosity functions (LFs) and number counts based on the Karl G. Jansky Very Large Array-COSMOS 3 GHz Large Project. The radio-selected sample of 7826 galaxies with robust optical/near-infrared counterparts with excellent photometric coverage allows us to construct the total radio LF since z 5.7. Using the Markov chain Monte Carlo algorithm, we fit the redshift dependent pure luminosity evolution model to the data and compare it with previously published VLA-COSMOS LFs obtained on individual populations of radio-selected star-forming galaxies and galaxies hosting active galactic nuclei classified on the basis of presence or absence of a radio excess with respect to the star-formation rates derived from the infrared emission. We find they are in excellent agreement, thus showing the reliability of the radio excess method in selecting these two galaxy populations at radio wavelengths. We study radio number counts down to submicrojansky levels drawn from different models of evolving LFs. We show that our evolving LFs are able to reproduce the observed radio sky brightness, even though we rely on extrapolations toward the faint end. Our results also imply that no new radio-emitting galaxy population is present below 1 μJy. Our work suggests that selecting galaxies with radio flux densities between 0.1 and 10 μJy will yield a star-forming galaxy in 90-95% of the cases with a high percentage of these galaxies existing around a redshift of z 2, thus providing useful constraints for planned surveys with the Square Kilometer Array and its precursors.

Galaxy Evolution in the Reddest Possible Filter

NASA Astrophysics Data System (ADS)

Richards, E. A.

We describe an observational programme aimed at understanding the radio emission from distant, rapidly evolving galaxy populations. These observations were carried out at 1.4 and 8.5 GHz with the VLA, centred on the Hubble Deep Field, obtaining limiting flux densities of 40 and 8 μJy respectively. The differential count of the radio sources is marginally sub-Euclidean to the completeness limits (γ = - 2.4 +/- 0.1) and fluctuation analysis suggests nearly 60 sources per arcmin^2 at the 1 μJy level. Using high-resolution 1.4 GHz observations obtained with MERLIN, we resolve all radio sources detected in the VLA complete sample and measure a median angular size for the microjansky radio population of 1-2``. This clue, coupled with the steep spectral index of the 1.4 GHz selected sample, suggests diffuse synchrotron radiation in z ~ 1 galactic discs. The wide-field HST and ground-based optical exposures show that the radio sources are identified primarily with disc systems composed of irregulars, peculiars, interacting/merging galaxies and a few isolated field spirals. Only 20% of the radio sources can be attributed to AGN - the majority are probably associated with starburst activity. The available redshifts range from 0.1 to 3, with a mean of about 0.8. We are plrobably witnessing a major episode of starburst activity in these luminous (L > L_*) systems, occasionally accompanied by an embedded AGN. About 20% of the radio sources remain unidentified to I = 26-28 in the HDF and flanking fields. Several of these objects have extremely red counterparts. We suggest that these are high-redshift dusty protogalaxies.

The environmental properties of radio-emitting AGN

NASA Astrophysics Data System (ADS)

Magliocchetti, M.; Popesso, P.; Brusa, M.; Salvato, M.

2018-05-01

We study the environmental properties of z≲ 1.2 radio-selected AGN belonging to the ˜2 deg2 of the COSMOS field, finding that about 20% of them appear within overdense structures. AGN with P_{1.4 GHz}>10^{23.5} W Hz^{-1} sr^{-1} are twice more likely to be found in clusters with respect to fainter sources (˜38% vs ˜15%), just as radio-selected AGN with stellar masses M* > 1011M⊙ are twice more likely to be found in overdense environments with respect to objects of lower mass (˜24% vs ˜11%). Comparisons with galaxy samples further suggest that radio-selected AGN of large stellar mass tend to avoid underdense environments more than normal galaxies with the same stellar content. Stellar masses also seem to determine the location of radio-active AGN within clusters: ˜100% of the sources found as satellite galaxies have M* < 1011.3M⊙, while ˜100% of the AGN coinciding with a cluster central galaxy have M* > 1011M⊙. No different location within the cluster is instead observed for AGN of various radio luminosities. Radio AGN which also emit in the MIR show a marked preference to be found as isolated galaxies (˜70%) at variance with those also active in the X-ray which all seem to reside within overdensities. What emerges from our work is a scenario whereby physical processes on sub-pc and kpc scales (e.g. emission respectively related to the AGN and to star formation) are strongly interconnected with the large-scale environment of the AGN itself.

Long-term multiwavelength studies of high-redshift blazar 0836+710

DOE PAGES

Akyuz, A.; Thompson, D. J.; Donato, D.; ...

2013-07-30

The observation of γ-ray flares from blazar 0836+710 in 2011, following a period of quiescence, offered an opportunity to study correlated activity at different wavelengths for a high-redshift (z = 2.218) active galactic nucleus. Here, optical and radio monitoring, plus Fermi-LAT γ-ray monitoring provided 20082–2012 coverage, while Swift offered auxiliary optical, ultraviolet, and X-ray information. Other contemporaneous observations were used to construct a broad-band spectral energy distribution. As a result, there is evidence of correlation but not a measurable lag between the optical and γ-ray flaring emission. In contrast, there is no clear correlation between radio and γ-ray activity, indicatingmore » radio emission regions that are unrelated to the parts of the jet that produce the γ rays. In conclusion, the γ-ray energy spectrum is unusual in showing a change of shape from a power law to a curved spectrum when going from the quiescent state to the active state.« less

Interstellar scintillation as the origin of the rapid radio variability of the quasar J1819+3845.

PubMed

Dennett-Thorpe, J; de Bruyn, A G

2002-01-03

The liberation of gravitational energy as matter falls onto a supermassive black hole at the centre of a galaxy is believed to explain the high luminosity of quasars. The variability of this emission from quasars and other types of active galactic nuclei can provide information on the size of the emitting regions and the physical process of fuelling the black hole. Some active galactic nuclei are variable at optical (and shorter) wavelengths, and display radio outbursts over years and decades. These active galactic nuclei often also show faster intraday variability at radio wavelengths. The origin of this rapid variability has been extensively debated, but a correlation between optical and radio variations in some sources suggests that both are intrinsic. This would, however, require radiation brightness temperatures that seem physically implausible, leading to the suggestion that the rapid variations are caused by scattering of the emission by the interstellar medium inside our Galaxy. Here we show that the rapid variations in the extreme case of quasar J1819+3845 (ref. 10) indeed arise from interstellar scintillation. The transverse velocity of the scattering material reveals the presence of plasma with a surprisingly high velocity close to the Solar System.

The effect of various parameters of large scale radio propagation models on improving performance mobile communications

NASA Astrophysics Data System (ADS)

Pinem, M.; Fauzi, R.

2018-02-01

One technique for ensuring continuity of wireless communication services and keeping a smooth transition on mobile communication networks is the soft handover technique. In the Soft Handover (SHO) technique the inclusion and reduction of Base Station from the set of active sets is determined by initiation triggers. One of the initiation triggers is based on the strong reception signal. In this paper we observed the influence of parameters of large-scale radio propagation models to improve the performance of mobile communications. The observation parameters for characterizing the performance of the specified mobile system are Drop Call, Radio Link Degradation Rate and Average Size of Active Set (AS). The simulated results show that the increase in altitude of Base Station (BS) Antenna and Mobile Station (MS) Antenna contributes to the improvement of signal power reception level so as to improve Radio Link quality and increase the average size of Active Set and reduce the average Drop Call rate. It was also found that Hata’s propagation model contributed significantly to improvements in system performance parameters compared to Okumura’s propagation model and Lee’s propagation model.

Effects of the 2017 Solar Eclipse on HF Radio Propagation and the D-Region Ionosphere: Citizen Science Investigation

NASA Astrophysics Data System (ADS)

Fry, C. D.; Adams, M.; Gallagher, D. L.; Habash Krause, L.; Rawlins, L.; Suggs, R. M.; Anderson, S. C.

2017-12-01

August 21, 2017 provided a unique opportunity to investigate the effects of the total solar eclipse on high frequency (HF) radio propagation and ionospheric variability. In Marshall Space Flight Center's partnership with the US Space and Rocket Center (USSRC) and Austin Peay State University (APSU), we engaged students and citizen scientists in an investigation of the eclipse effects on the mid-latitude ionosphere. The Amateur Radio community has developed several automated receiving and reporting networks that draw from widely-distributed, automated and manual radio stations to build a near-real time, global picture of changing radio propagation conditions. We used these networks and employed HF radio propagation modeling in our investigation. A Ham Radio Science Citizen Investigation (HamSCI) collaboration with the American Radio Relay League (ARRL) ensured that many thousands of amateur radio operators would be "on the air" communicating on eclipse day, promising an extremely large quantity of data would be collected. Activities included implementing and configuring software, monitoring the HF Amateur Radio frequency bands and collecting radio transmission data on days before, the day of, and days after the eclipse to build a continuous record of changing propagation conditions as the moon's shadow marched across the United States. Our expectations were the D-Region ionosphere would be most impacted by the eclipse, enabling over-the-horizon radio propagation on lower HF frequencies (3.5 and 7 MHz) that are typically closed during the middle of the day. Post-eclipse radio propagation analysis provided insights into ionospheric variability due to the eclipse. We report on results, interpretation, and conclusions of these investigations.

Tracking Galaxy Evolution Through Low-Frequency Radio Continuum Observations using SKA and Citizen-Science Research using Multi-Wavelength Data

NASA Astrophysics Data System (ADS)

Hota, Ananda; Konar, C.; Stalin, C. S.; Vaddi, Sravani; Mohanty, Pradeepta K.; Dabhade, Pratik; Dharmik Bhoga, Sai Arun; Rajoria, Megha; Sethi, Sagar

2016-12-01

We present a brief review of progress in the understanding of general spiral and elliptical galaxies, through merger, star formation and AGN activities. With reference to case studies performed with the GMRT, we highlight the unique aspects of studying galaxies in the radio wavelengths where powerful quasars and bright radio galaxies are traditionally the dominating subjects. Though AGN or quasar activity is extremely energetic, it is extremely short-lived. This justify focussing on transitional galaxies to find relic-evidences of the immediate past AGN-feedback which decide the future course of evolution of a galaxy. Relic radio lobes can be best detected in low frequency observations with the GMRT, LOFAR and in future SKA. The age of these relic radio plasma can be as old as a few hundred Myr. There is a huge gap between this and what is found in optical bands. The very first relic-evidences of a past quasar activity (Hanny's Voorwerp) was discovered in 2007 by a Galaxy Zoo citizen-scientist, a school teacher, in the optical bands. This relic is around a few tens of thousand years old. More discoveries needed to match these time-scales with star formation time-scales in AGN host galaxies to better understand black hole galaxy co-evolution process via feedback-driven quenching of star formation. It is now well-accepted that discovery and characterization of such faint fuzzy relic features can be more efficiently done by human eye than a machine. Radio interferometry images are more complicated than optical and need the citizen-scientists to be trained. RAD@home, the only Indian citizen-science research project in astronomy, analysing TIFR GMRT Sky Survey (TGSS) 150 MHz data and observing from the Giant Meterwave Radio Telescope (GMRT), was launched in April 2013. Unique, zero-infrastructure zero-funded design of RAD@home as a collaboratory of 69 trained e-astronomers is briefly described. Some of the new-found objects like episodic radio galaxies, radio-jet and companion galaxy interaction, radio galaxy bent by motion of the intra-filament medium in a Mpc-scale galaxy filament etc. are briefly presented as demonstration of its potential. Citizen-science has not only opened up a new way for astronomy research but also possibly the only promising way to extract maximum science out of the Big Data in the SKA-era. This possibly can convert the Big Data problem into a prospect. Citizen-science can contribute to the knowledge creation in never-seen-before speed and in approach. As it is based on internet, it can provide an equal opportunity of academic-growth to people even in the under-developed regions where we always need to put our optical and radio telescopes. This can liberate the research-activity of city-based research-institutes out of the four brick walls and alleviate various socio-economic and geo-political constraints on growth of citizens educated in undergraduate-level science but located in remote areas.

Defense Logistics: A Completed Comprehensive Strategy is Needed to Guide DOD’s In-Transit Visibility Efforts

DTIC Science & Technology

2013-02-01

Defense Logistics List of Abbreviations aRFID active radio frequency identification DOD Department of Defense RFID...The Navy and the Air Force each have their own Active Radio Frequency Identification ( aRFID ) Migration Program. These two programs are included...with the aRFID Program and the aRFID Infrastructure, respectively and are therefore not listed in the table. Appendix III: Comments from the

Solar radio continuum storms and a breathing magnetic field model

NASA Technical Reports Server (NTRS)

1975-01-01

Radio noise continuum emissions observed in metric and decametric wave frequencies are, in general, associated with actively varying sunspot groups accompanied by the S-component of microwave radio emissions. These continuum emission sources, often called type I storm sources, are often associated with type III burst storm activity from metric to hectometric wave frequencies. This storm activity is, therefore, closely connected with the development of these continuum emission sources. It is shown that the S-component emission in microwave frequencies generally precedes, by several days, the emission of these noise continuum storms of lower frequencies. In order for these storms to develop, the growth of sunspot groups into complex types is very important in addition to the increase of the average magnetic field intensity and area of these groups. After giving a review on the theory of these noise continuum storm emissions, a model is briefly considered to explain the relation of the emissions to the storms.

Cygnus X-3 Returns to an Active State

NASA Astrophysics Data System (ADS)

McCollough, Michael L.; Koljonen, Karri; Gurwell, Mark A.; Trushkin, Sergei; Pooley, Guy G.

2017-08-01

Cygnus X-3 is a well-known microquasar composed of a mass-donating Wolf-Rayet star and a compact object. Recently, Cygnus X-3 has been in a quiescent state for an extended period of time (2011-2016) but returned to an active state on two occasions during 2016/2017 including quenched/hypersoft states, gamma-ray emission, and major radio flares. During these two periods of activity, we undertook multi-wavelength observing campaigns with observations in the radio (RATAN-600, AMI-LA, Metsähovi), submillimeter (SMA, EHT), X-ray (Swift/XRT, MAXI), hard X-ray (Swift/BAT, NuSTAR), and gamma-ray (AGILE, Fermi, VERITAS). At the peak of the major radio flare in April 2017 observations were made with VERITAS (TeV), NuSTAR (hard X-ray), and the Event Horizon Telescope (submillimeter). In this presentation, I will review these observing campaigns and the insights they provide about Cygnus X-3.

Carbon Beam Radio-Therapy and Research Activities at HIMAC

NASA Astrophysics Data System (ADS)

Kanazawa, Mitsutaka

2007-05-01

Radio-therapy with carbon ion beam has been carried out since 1994 at HIMAC (Heavy Ion Medical Accelerator in Chiba) in NIRS (National Institute of Radiological Sciences). Now, many types of tumors can be treated with carbon beam with excellent local controls of the tumors. Stimulated with good clinical results, requirement of the dedicated compact facility for carbon beam radio-therapy is increased. To realize this requirement, design study of the facility and the R&D's of the key components in this design are promoted by NIRS. According successful results of these activities, the dedicated compact facility will be realized in Gunma University. In this facility, the established irradiation method is expected to use, which is passive irradiation method with wobbler magnets and ridge filter. In this presentation, above R&D's will be presented together with clinical results and basic research activities at HIMAC.

A Search for X-ray Emission from the First Magnetically Active T Dwarf

NASA Astrophysics Data System (ADS)

Williams, Peter

2015-09-01

Ultracool dwarfs (spectral types >M7) were long expected to be magnetically inactive, but concerted X-ray and radio observations (mostly by our group) have led to the discovery of magnetic activity and a characterization of its basic properties. We have recently discovered periodic radio bursts from the T6.5 dwarf 2MASS 1047+21, by far the coolest (900 K) substellar object detected in the radio, implying high levels of magnetic activity well into the brown dwarf regime and making it a uniquely compelling target in the challenging search for ultracool X-ray emission. We propose a 40 ks observation with ACIS-S and the VLA that will cover 6 full rotations, place the deepest constraints on X-ray luminosity to date, and may lead to the first detection of X-ray emission from a T dwarf.

Remote enzyme activation using gold coated magnetite as antennae for radio frequency fields

NASA Astrophysics Data System (ADS)

Collins, Christian B.; Ackerson, Christopher J.

2018-02-01

The emerging field of remote enzyme activation, or the ability to remotely turn thermophilic increase enzyme activity, could be a valuable tool for understanding cellular processes. Through exploitation of the temperature dependence of enzymatic processes and high thermal stability of thermophilic enzymes these experiments utilize nanoparticles as `antennae' that convert radiofrequency (RF) radiation into local heat, increasing activity of the enzymes without increasing the temperature of the surrounding bulk solution. To investigate this possible tool, thermolysin, a metalloprotease was covalently conjugated to 4nm gold coated magnetite particles via peptide bond formation with the protecting ligand shell. RF stimulated protease activity at 17.76 MHz in a solenoid shaped antenna, utilizing both electric and magnetic field interactions was investigated. On average 40 percent higher protease activity was observed in the radio frequency fields then when bulk heating the sample to the same temperature. This is attributed to electrophoretic motion of the nanoparticle enzyme conjugates and local regions of heat generated by the relaxation of the magnetite cores with the oscillating field. Radio frequency local heating of nanoparticles conjugated to enzymes as demonstrated could be useful in the activation of specific enzymes in complex cellular environments.

75 FR 2481 - Submission for OMB; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-15

... audience size and composition for broadcasts; and assess signal reception, credibility and relevance of... announces that the information collection activity titled, ``Surveys and Other Audience Research for Radio... to the burden hours. Title: Interviews and Other Audience Research for Radio and TV Marti. Abstract...

REGENERATION AND REACTIVATION OF CARBON ADSORBENTS BY RADIO FREQUENCY INDUCTION HEATING

EPA Science Inventory

1. Electrical Properties of Adsorbents: We measured the electric permittivity of four commercially available carbon adsorbents (supplied by Wesvaco Inc) over the radio frequency range (1 to 40 MHz). Westvaco is by far the largest volume supplier of activated carbon...

NEW CLASS OF VERY HIGH ENERGY {gamma}-RAY EMITTERS: RADIO-DARK MINI SHELLS SURROUNDING ACTIVE GALACTIC NUCLEUS JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kino, Motoki; Ito, Hirotaka; Kawakatu, Nozomu

We explore non-thermal emission from a shocked interstellar medium, which is identified as an expanding shell, driven by a relativistic jet in active galactic nuclei (AGNs). In this work, we particularly focus on parsec-scale size mini shells surrounding mini radio lobes. From the radio to X-ray band, the mini radio lobe emission dominates the faint emission from the mini shell. On the other hand, we find that inverse-Compton (IC) emission from the shell can overwhelm the associated lobe emission at the very high energy (VHE; E > 100 GeV) {gamma}-ray range, because energy densities of synchrotron photons from the lobemore » and/or soft photons from the AGN nucleus are large and IC scattering works effectively. The predicted IC emission from nearby mini shells can be detected with the Cherenkov Telescope Array and they are potentially a new class of VHE {gamma}-ray emitters.« less

Advances in solar radio astronomy

NASA Technical Reports Server (NTRS)

Kundu, M. R.

1982-01-01

The status of the observations and interpretations of the sun's radio emission covering the entire radio spectrum from millimeter wavelengths to hectometer and kilometer wavelengths is reviewed. Emphasis is given to the progress made in solar radio physics as a result of recent advances in plasma and radiation theory. It is noted that the capability now exists of observing the sun with a spatial resolution of approximately a second of arc and a temporal resolution of about a millisecond at centimeter wavelengths and of obtaining fast multifrequency two-dimensional pictures of the sun at meter and decameter wavelengths. A summary is given of the properties of nonflaring active regions at millimeter, centimeter, and meter-decameter wavelengths. The properties of centimeter wave bursts are discussed in connection with the high spatial resolution observations. The observations of the preflare build-up of an active region are reviewed. High spatial resolution observations (a few seconds of arc to approximately 1 arcsec) are discussed, with particular attention given to the one- and two-dimensional maps of centimeter-wavelength burst sources.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1992-01-01

Archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) are provided. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, in supporting research and technology, in implementation, and in operations. Also included is standards activity at JPL for space data and information. In the search for extraterrestrial intelligence (SETI), the TDA Progress Report reports on implementation and operations for searching the microwave spectrum. Topics covered include tracking and ground-based navigation; communications, spacecraft-ground; station control and system technology; capabilities for new projects; network upgrade and sustaining; network operations and operations support; and TDA program management and analysis.

Centaurus A, the core of the problem

NASA Technical Reports Server (NTRS)

Tingay, S. J.; Jauncey, D. L.; Preston, R. A.; Reynolds, J. E.; Meier, D. L.; Tzioumis, A. K.; Jones, D. L.; King, E. A.; Amy, S. W.; Biggs, J. D.

1994-01-01

The bright, peculiar elliptical galaxy Centaurus A (NGC 5128, PKS 1322-427) was one of the first extragalactic radio sources to be optically identified (Bolton et al. 1949). At a distance of 4 Mpc, Centaurus A is the closest active radio galaxy and affords the highest linear imaging resolution (1 mas approximately equal to 0.02 pc) and hence the best prospects for studying an active nucleus close to the central radio source. We present the results of multi-epoch, 8.4-GHz, very long baseline interferometry (VLBI), imaging observations of the nucleus made over the past three years. The nucleus possesses a core-jet structure where the inner portion of the jet shows apparent linear motion with a velocity substantially less than the speed of light.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1992-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, in supporting research and technology, in implementation, and in operations. Also included is standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Operations (OSO). The TDA Office also performs work funded by two other NASA program offices through and with the cooperation of the OSO. These are the Orbital Debris Radar Program and 21st Century Communication Studies.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, Edward C. (Editor)

1993-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) in the following areas: space communications, radio navigation, radio science, and ground-based radio and radar astronomy. This document also reports on the activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC). The TDA Office also performs work funded by another NASA program office through and with the cooperation of OSC. This is the Orbital Debris Radar Program with the Office of Space Systems Development.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1995-01-01

This quarterly publiction provides archival reports on developments in programs managed by JPL Telecommunications and Mission Operations Directorate (TMOD), which now includes the former communications and Data Acquisition (TDA) Office. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The Orbital Debris Radar Program, funded by the Office of Space Systems Development, makes use of the planetary radar capability when the antennas are configured at science instruments making direct observations of planets, their satellites, and asteroids of our solar system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dowla, F

Long-range, ultra-wideband (UWB), passive radio frequency (RF) tags are key components in Radio Frequency IDentification (RFID) system that will revolutionize inventory control and tracking applications. Unlike conventional, battery-operated (active) RFID tags, LLNL's small UWB tags, called 'UTag', operate at long range (up to 20 meters) in harsh, cluttered environments. Because they are battery-less (that is, passive), they have practically infinite lifetimes without human intervention, and they are lower in cost to manufacture and maintain than active RFID tags. These robust, energy-efficient passive tags are remotely powered by UWB radio signals, which are much more difficult to detect, intercept, and jammore » than conventional narrowband frequencies. The features of long range, battery-less, and low cost give UTag significant advantage over other existing RFID tags.« less

Amateur Planetary Radio Data Archived for Science and Education: Radio Jove

NASA Astrophysics Data System (ADS)

Thieman, J.; Cecconi, B.; Sky, J.; Garcia, L. N.; King, T. A.; Higgins, C. A.; Fung, S. F.

2015-12-01

The Radio Jove Project is a hands-on educational activity in which students, teachers, and the general public build simple radio telescopes, usually from a kit, to observe single frequency decameter wavelength radio emissions from Jupiter, the Sun, the galaxy, and the Earth usually with simple dipole antennas. Some of the amateur observers have upgraded their receivers to spectrographs and their antennas have become more sophisticated as well. The data records compare favorably to more sophisticated professional radio telescopes such as the Long Wavelength Array (LWA) and the Nancay Decametric Array. Since these data are often carefully calibrated and recorded around the clock in widely scattered locations they represent a valuable database useful not only to amateur radio astronomers but to the professional science community as well. Some interesting phenomena have been noted in the data that are of interest to the professionals familiar with such records. The continuous monitoring of radio emissions from Jupiter could serve as useful "ground truth" data during the coming Juno mission's radio observations of Jupiter. Radio Jove has long maintained an archive for thousands of Radio Jove observations, but the database was intended for use by the Radio Jove participants only. Now, increased scientific interest in the use of these data has resulted in several proposals to translate the data into a science community data format standard and store the data in professional archives. Progress is being made in translating Radio Jove data to the Common Data Format (CDF) and also in generating new observations in that format as well. Metadata describing the Radio Jove data would follow the Space Physics Archive Search and Extract (SPASE) standard. The proposed archive to be used for long term preservation would be the Planetary Data System (PDS). Data sharing would be achieved through the PDS and the Paris Astronomical Data Centre (PADC) and the Virtual Wave Observatory (VWO). We believe that Radio Jove represents another fertile area for citizen science to contribute to overall scientific investigation.

Radio astronomy

NASA Technical Reports Server (NTRS)

Kellermann, Kenneth I.; Heeschen, David; Backer, Donald C.; Cohen, Marshall H.; Davis, Michael; Depater, Imke; Deyoung, David; Dulk, George A.; Fisher, J. R.; Goss, W. Miller

1991-01-01

The following subject areas are covered: (1) scientific opportunities (millimeter and sub-millimeter wavelength astronomy; meter to hectometer astronomy; the Sun, stars, pulsars, interstellar masers, and extrasolar planets; the planets, asteroids, and comets; radio galaxies, quasars, and cosmology; and challenges for radio astronomy in the 1990's); (2) recommendations for new facilities (the millimeter arrays, medium scale instruments, and small-scale projects); (3) continuing activities and maintenance, upgrading of telescopes and instrumentation; (4) long range programs and technology development; and (5) social, political, and organizational considerations.

Activity of radio-tagged black-footed ferrets

USGS Publications Warehouse

Biggins, Dean E.; Shroeder, Max H.; Forrest, Steven C.; Richardson, Louise

1986-01-01

Activity of two radio-tagged black-footed ferrets (Mustela nigripes) was investigated during October-November 1981 (an adult male monitored for 16 days), and during August-November 1982 (a young female monitored for 101 days). Aboveground activity of the male averaged 2.95 hr/night, 15% of the total time monitored. From 22 September to 5 November, aboveground activity of the female averaged 1.9 hours; 26% of the time she was stationary and 74% of the time she was moving. During August the juvenile female emerged at least once on 93% of the nights. She was least active in November. Both animals were primarily nocturnal (although daylight activity was not uncommon), and timing of nightly activity was similar, peaking from 0100 to 0359.

The Influence of Western Radio on the Democratization of Soviet Youth.

ERIC Educational Resources Information Center

Manaev, Oleg

1991-01-01

Finds that the openness toward broadcasts from Radio Liberty and other Western stations during perestroika has only increased the level of distrust of the Soviet media by those teenagers who tend to be poorly adapted to the established social activities of their peers. (PRA)

Interpreting radiative efficiency in radio-loud AGNs

NASA Astrophysics Data System (ADS)

Hardcastle, Martin

2018-04-01

Radiative efficiency in radio-loud active galactic nuclei is governed by the accretion rate onto the central black hole rather than directly by the type of accreted matter; while it correlates with real differences in host galaxies and environments, it does not provide unambiguous information about particular objects.

Warkworth 12-m VLBI Station: WARK12M

NASA Technical Reports Server (NTRS)

Weston, Stuart; Takiguchi, Hiroshi; Natusch, Tim; Woodburn, Lewis; Gulyaev, Sergei

2013-01-01

The Warkworth 12-m radio telescope is operated by the Institute for Radio Astronomy and Space Research (IRASR) at AUT University, Auckland, New Zealand. Here we review the characteristics of the 12-m VLBI station and report on a number of activities and technical developments in 2012.

Kashima 34-m Radio Telescope

NASA Technical Reports Server (NTRS)

Sekido, Mamoru; Kawai, Eiji

2013-01-01

The Kashima 34-m radio telescope has been continuously operated and maintained by the National Institute of Information and Communications Technology (NICT) as a facility of the Kashima Space Technology Center (KSTC) in Japan. This brief report summarizes the status of this telescope, the staff, and activities during 2012.

Low-mass Active Galactic Nuclei on the Fundamental Plane of Black Hole Activity

NASA Astrophysics Data System (ADS)

Qian, Lei; Dong, Xiao-Bo; Xie, Fu-Guo; Liu, Wenjuan; Li, Di

2018-06-01

It is widely known that in active galactic nuclei (AGNs) and black hole X-ray binaries (BHXBs), there is a tight correlation among their radio luminosity (L R ), X-ray luminosity (L X), and BH mass ({M}BH}), the so-called “fundamental plane” (FP) of BH activity. Yet the supporting data are very limited in the {M}BH} regime between stellar mass (i.e., BHXBs) and 106.5 {M}ȯ (namely, the lower bound of supermassive BHs in common AGNs). In this work, we developed a new method to measure the 1.4 GHz flux directly from the images of the VLA FIRST survey, and apply it to the type-1 low-mass AGNs in the Dong et al. sample. As a result, we obtained 19 new low-mass AGNs for FP research with both {M}BH} estimates ({M}BH} ≈ 105.5–6.5 {M}ȯ ), reliable X-ray measurements, and (candidate) radio detections, tripling the number of such candidate sources in the literature. Most (if not all) of the low-mass AGNs follow the standard radio/X-ray correlation and the universal FP relation fitted with the combined data set of BHXBs and supermassive AGNs by Gültekin et al.; the consistency in the radio/X-ray correlation slope among those accretion systems supports the picture that the accretion and ejection (jet) processes are quite similar in all accretion systems of different {M}BH}. In view of the FP relation, we speculate that the radio loudness { \\mathcal R } (i.e., the luminosity ratio of the jet to the accretion disk) of AGNs depends not only on Eddington ratio, but probably also on {M}BH}.

Assessing the effects of timing irregularities on radio pulsars anomalous braking indices

NASA Astrophysics Data System (ADS)

Chukwude, A. E.; Chidi Odo, Finbarr

2016-10-01

We investigate the statistical effects of non-discrete timing irregularities on observed radio pulsar braking indices using correlations between the second derivative of the measured anomalous frequency (̈νobs) and some parameters that have been widely used to quantify pulsar timing fluctuations (the timing activity parameter (A), the amount of timing fluctuations absorbed by the cubic term (σR23) and a measure of pulsar rotational stability (σz)) in a large sample of 366 Jodrell Bank Observatory radio pulsars. The result demonstrates that anomalous braking indices are largely artifacts produced by aggregations of fluctuations that occur within or outside the pulsar system. For a subsample of 223 normal radio pulsars whose observed timing activity appeared consistent with instabilities in rotation of the underlying neutron stars (or timing noise) over timescales of ˜ 10 - 40 yr, |̈νobs| strongly correlates (with correlation coefficient |r| ˜ 0.80 - 0.90) with the pulsar timing activity parameters and spin-down properties. On the other hand, no meaningful correlations (r < 0.3) were found between ̈νobs and the timing activity diagnostics and spin-down parameters in the remaining 143 objects, whose timing activity appears significantly dominated by white noise fluctuations. The current result can be better understood if the timing noise in isolated pulsars originates from intrinsic spin-down processes of the underlying neutron stars, but white noise fluctuations largely arise from processes external to the pulsar system.

The 60 micron to 20 centimeter infrared-to-radio ratio within spiral galaxies

NASA Technical Reports Server (NTRS)

Bicay, M. D.; Helou, G.

1990-01-01

A detailed comparison is presented of the distribution of 60 micron IR and 20 cm radio continuum emission within 25 galaxies, mostly disk spirals. Local maxima in the thermal IR and nonthermal radio emission are found to be spatially coincident on scales of less than about 0.4 kpc in the nearest sample galaxies. The IR-red disk in normal spirals appears to be characterized by a shorter scale length than that of the radio continuum disk, suggesting that the IR-to-radio ratio should decrease as a function of radius. A model that successfully accounts for the observations is introduced which is based on the assumptions of steady-state star formation activity within the disk on kpc scales and a tight coupling between the origins of the dust-heating radiation and the radio-emitting cosmic-ray electrons. The underlying source is described as an exponential disk. The results also suggest that a random walk process cannot by itself describe the temporal evolution of cosmic rays.

Planck intermediate results: XLV. Radio spectra of northern extragalactic radio sources

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Aller, H. D.; ...

2016-12-12

Continuum spectra covering centimetre to submillimetre wavelengths are presented in this paper for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37 GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at highmore » frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Finally, variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.« less

Planck intermediate results. XLV. Radio spectra of northern extragalactic radio sources

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Aller, H. D.; Aller, M. F.; Arnaud, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Burigana, C.; Calabrese, E.; Catalano, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombo, L. P. L.; Couchot, F.; 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.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gurwell, M. A.; Hansen, F. K.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hobson, M.; Hornstrup, A.; Hovatta, T.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Järvelä, E.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Max-Moerbeck, W.; Meinhold, P. R.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Mingaliev, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nati, F.; Natoli, P.; Nieppola, E.; Noviello, F.; Novikov, D.; Novikov, I.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Ramakrishnan, V.; Rastorgueva-Foi, E. A.; S Readhead, A. C.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Richards, J. L.; Ristorcelli, I.; Rocha, G.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Savelainen, M.; Savini, G.; Scott, D.; Sotnikova, Y.; Stolyarov, V.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tammi, J.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tornikoski, M.; Tristram, M.; Tucci, M.; Türler, M.; Valenziano, L.; Valiviita, J.; Valtaoja, E.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wehrle, A. E.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-12-01

Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37 GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at high frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.

Photometric redshifts for the next generation of deep radio continuum surveys - I. Template fitting

NASA Astrophysics Data System (ADS)

Duncan, Kenneth J.; Brown, Michael J. I.; Williams, Wendy L.; Best, Philip N.; Buat, Veronique; Burgarella, Denis; Jarvis, Matt J.; Małek, Katarzyna; Oliver, S. J.; Röttgering, Huub J. A.; Smith, Daniel J. B.

2018-01-01

We present a study of photometric redshift performance for galaxies and active galactic nuclei detected in deep radio continuum surveys. Using two multiwavelength data sets, over the NOAO Deep Wide Field Survey Boötes and COSMOS fields, we assess photometric redshift (photo-z) performance for a sample of ∼4500 radio continuum sources with spectroscopic redshifts relative to those of ∼63 000 non-radio-detected sources in the same fields. We investigate the performance of three photometric redshift template sets as a function of redshift, radio luminosity and infrared/X-ray properties. We find that no single template library is able to provide the best performance across all subsets of the radio-detected population, with variation in the optimum template set both between subsets and between fields. Through a hierarchical Bayesian combination of the photo-z estimates from all three template sets, we are able to produce a consensus photo-z estimate that equals or improves upon the performance of any individual template set.

Planck intermediate results: XLV. Radio spectra of northern extragalactic radio sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aghanim, N.; Aller, H. D.

Continuum spectra covering centimetre to submillimetre wavelengths are presented in this paper for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37 GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at highmore » frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Finally, variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.« less

Tracking of an electron beam through the solar corona with LOFAR

NASA Astrophysics Data System (ADS)

Mann, G.; Breitling, F.; Vocks, C.; Aurass, H.; Steinmetz, M.; Strassmeier, K. G.; Bisi, M. M.; Fallows, R. A.; Gallagher, P.; Kerdraon, A.; Mackinnon, A.; Magdalenic, J.; Rucker, H.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Best, P.; Bîrzan, L.; Bonafede, A.; Broderick, J. W.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Corstanje, A.; Gasperin, F. de; Geus, E. de; Deller, A.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; van Haarlem, M.; Hassall, T. E.; Heald, G.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Horneffer, A.; Juette, E.; Karastergiou, A.; Klijn, W. F. A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Maat, P.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Rafferty, D.; Reich, W.; Röttgering, H.; Scaife, A. M. M.; Schwarz, D. J.; Serylak, M.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; van Weeren, R. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, J. A.

2018-03-01

The Sun's activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spectra. They are usually interpreted as signatures of beams of energetic electrons propagating along coronal magnetic field lines. Here we present novel interferometric LOFAR (LOw Frequency ARray) observations of three solar type-III radio bursts and their reverse bursts with high spectral, spatial, and temporal resolution. They are consistent with a propagation of the radio sources along the coronal magnetic field lines with nonuniform speed. Hence, the type-III radio bursts cannot be generated by a monoenergetic electron beam, but by an ensemble of energetic electrons with a spread distribution in velocity and energy. Additionally, the density profile along the propagation path is derived in the corona. It agrees well with three-fold coronal density model by (1961, ApJ, 133, 983).

Influence of January 2009 stratospheric warming on HF radio wave propagation in the low-latitude ionosphere

NASA Astrophysics Data System (ADS)

Kotova, Darya; Klimenko, Maksim; Klimenko, Vladimir; Zaharov, Veniamin; Bessarab, Fedor; Korenkov, Yuriy

2016-12-01

We have considered the influence of the January 23-27, 2009 sudden stratospheric warming (SSW) event on HF radio wave propagation in the equatorial ionosphere. This event took place during extremely low solar and geomagnetic activity. We use the simulation results obtained with the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) for simulating environmental changes during the SSW event. We both qualitatively and quantitatively reproduced total electron content disturbances obtained from global ground network receiver observations of GPS navigation satellite signals, by setting an additional electric potential and TIME-GCM model output at a height of 80 km. In order to study the influence of this SSW event on HF radio wave propagation and attenuation, we used the numerical model of radio wave propagation based on geometrical optics approximation. It is shown that the sudden stratospheric warming leads to radio signal attenuation and deterioration of radio communication in the daytime equatorial ionosphere.

RFID Transponders' Radio Frequency Emissions in Aircraft Communication and Navigation Radio Bands

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Williams, Reuben A.; Koppen, Sandra V.; Salud, Maria Theresa P.

2006-01-01

Radiated emissions in aircraft communication and navigation bands are measured from several active radio frequency identification (RFID) tags. The individual tags are different in design and operations. They may also operate in different frequency bands. The process for measuring the emissions is discussed, and includes tag interrogation, reverberation chamber testing, and instrument settings selection. The measurement results are described and compared against aircraft emission limits. In addition, interference path loss for the cargo bays of passenger aircraft is measured. Cargo bay path loss is more appropriate for RFID tags than passenger cabin path loss. The path loss data are reported for several aircraft radio systems on a Boeing 747 and an Airbus A320.

Radio astronomy Explorer-B postlaunch attitude operations analysis

NASA Technical Reports Server (NTRS)

Werking, R. D.; Berg, R.; Brokke, K.; Hattox, T.; Lerner, G.; Stewart, D.; Williams, R.

1974-01-01

The attitude support activities of the Radio Astronomy Explorer-B are reported. The performance of the spacecraft hardware and software are discussed along with details of the mission events, from launch through main boom deployment. Reproductions of displays are presented which were used during support activities. The interactive graphics proved the support function by providing the quality control necessary to ensure mission success in an environment where flight simulated ground testing of spacecraft hardware cannot be performed.

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

DOE PAGES

van Weeren, R. J.; Ogrean, G. A.; Jones, C.; ...

2017-01-31

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ~0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. Here, we detect a density discontinuity north-northeast of this core, which we speculatemore » is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.« less

How safe is tuning a radio?: using the radio tuning task as a benchmark for distracted driving.

PubMed

Lee, Ja Young; Lee, John D; Bärgman, Jonas; Lee, Joonbum; Reimer, Bryan

2018-01-01

Drivers engage in non-driving tasks while driving, such as interactions entertainment systems. Studies have identified glance patterns related to such interactions, and manual radio tuning has been used as a reference task to set an upper bound on the acceptable demand of interactions. Consequently, some view the risk associated with radio tuning as defining the upper limit of glance measures associated with visual-manual in-vehicle activities. However, we have little knowledge about the actual degree of crash risk that radio tuning poses and, by extension, the risk of tasks that have similar glance patterns as the radio tuning task. In the current study, we use counterfactual simulation to take the glance patterns for manual radio tuning tasks from an on-road experiment and apply these patterns to lead-vehicle events observed in naturalistic driving studies. We then quantify how often the glance patterns from radio tuning are associated with rear-end crashes, compared to driving only situations. We used the pre-crash kinematics from 34 crash events from the SHRP2 naturalistic driving study to investigate the effect of radio tuning in crash-imminent situations, and we also investigated the effect of radio tuning on 2,475 routine braking events from the Safety Pilot project. The counterfactual simulation showed that off-road glances transform some near-crashes that could have been avoided into crashes, and glance patterns observed in on-road radio tuning experiment produced 2.85-5.00 times more crashes than baseline driving. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

NASA Astrophysics Data System (ADS)

van Weeren, R. J.; Ogrean, G. A.; Jones, C.; Forman, W. R.; Andrade-Santos, F.; Pearce, Connor J. J.; Bonafede, A.; Brüggen, M.; Bulbul, E.; Clarke, T. E.; Churazov, E.; David, L.; Dawson, W. A.; Donahue, M.; Goulding, A.; Kraft, R. P.; Mason, B.; Merten, J.; Mroczkowski, T.; Nulsen, P. E. J.; Rosati, P.; Roediger, E.; Randall, S. W.; Sayers, J.; Umetsu, K.; Vikhlinin, A.; Zitrin, A.

2017-02-01

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ˜0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeast of this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100-300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Weeren, R. J.; Jones, C.; Forman, W. R.

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeast of this core, which we speculate ismore » associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.« less

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Weeren, R. J.; Ogrean, G. A.; Jones, C.

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ~0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. Here, we detect a density discontinuity north-northeast of this core, which we speculatemore » is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.« less

GREEN BANK TELESCOPE AND SWIFT X-RAY TELESCOPE OBSERVATIONS OF THE GALACTIC CENTER RADIO MAGNETAR SGR J1745–2900

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lynch, Ryan S.; Archibald, Robert F.; Kaspi, Victoria M.

We present results from eight months of Green Bank Telescope 8.7 GHz observations and nearly 18 months of Swift X-ray telescope observations of the radio magnetar SGR J1745–2900. We tracked the radio and X-ray flux density, polarization properties, profile evolution, rotation, and single-pulse behavior. We identified two main periods of activity. The first is characterized by approximately 5.5 months of relatively stable evolution in radio flux density, rotation, and profile shape, while in the second these properties varied substantially. Specifically, a third profile component emerged and the radio flux also became more variable. The single pulse properties also changed, mostmore » notably with a larger fraction of pulses with pulse widths ∼5–20 ms in the erratic state. Bright single pulses are well described by a log-normal energy distribution at low energies, but with an excess at high energies. The 2–10 keV flux decayed steadily since the initial X-ray outburst, while the radio flux remained stable to within ∼20% during the stable state. A joint pulsar timing analysis of the radio and X-ray data shows a level of timing noise unprecedented in a radio magnetar, though during the time covered by the radio data alone the timing noise was at a level similar to that observed in other radio magnetars. While SGR J1745–2900 is similar to other radio magnetars in many regards, it differs by having experienced a period of relative stability in the radio that now appears to have ended, while the X-ray properties evolved independently.« less

HamSCI: The Ham Radio Science Citizen Investigation

NASA Astrophysics Data System (ADS)

Frissell, N. A.; Moses, M. L.; Earle, G. D.; McGwier, R. W.; Miller, E. S.; Kaeppler, S. R.; Silver, H. W.; Ceglia, F.; Pascoe, D.; Sinanis, N.; Smith, P.; Williams, R.; Shovkoplyas, A.; Gerrard, A. J.

2016-12-01

Amateur (or "ham") radio operators are individuals with a non-pecuniary interest in radio technology, engineering, communications, science, and public service. They are licensed by their national governments to transmit on amateur radio frequencies. In many jurisdictions, there is no age requirement for a ham radio license, and operators from diverse backgrounds participate. There are more than 740,000 hams in the US, and over 3 million (estimated) worldwide. Many amateur communications are conducted using transionospheric links and thus affected by space weather and ionospheric processes. Recent technological advances have enabled the development of automated ham radio observation networks (e.g. the Reverse Beacon Network, www.reversebeacon.net) and specialized operating modes for the study of weak-signal propagation. The data from these networks have been shown to be useful for the study of ionospheric processes. In order to connect professional researchers with the volunteer-based ham radio community, HamSCI (Ham Radio Science Citizen Investigation, www.hamsci.org) has been established. HamSCI is a platform for publicizing and promoting projects that are consistent with the following objectives: (1) Advance scientific research and understanding through amateur radio activities. (2) Encourage the development of new technologies to support this research. (3) Provide educational opportunities for the amateur community and the general public. HamSCI researchers are working with the American Radio Relay League (ARRL, www.arrl.org) to publicize these objectives and recruit interested hams. The ARRL is the US national organization for amateur radio with a membership of over 170,000 and a monthly magazine, QST. HamSCI is currently preparing to support ionospheric research connected to the 21 Aug 2017 Total Solar Eclipse by expanding coverage of the Reverse Beacon Network and organizing a large-scale ham radio operating event ("QSO Party") to generate data during the eclipse.

The column density distribution of hard X-ray radio galaxies

NASA Astrophysics Data System (ADS)

Panessa, F.; Bassani, L.; Landi, R.; Bazzano, A.; Dallacasa, D.; La Franca, F.; Malizia, A.; Venturi, T.; Ubertini, P.

2016-09-01

In order to investigate the role of absorption in active galactic nuclei (AGN) with jets, we have studied the column density distribution of a hard X-ray selected sample of radio galaxies, derived from the INTEGRAL/Imager on Board the Integral Satellite (IBIS) and Swift/The Burst Alert Telescope (BAT) AGN catalogues (˜7-10 per cent of the total AGN population). The 64 radio galaxies have a typical FR II radio morphology and are characterized by high 20-100 keV luminosities (from 1042 to 1046 erg s-1) and high Eddington ratios (log LBol/LEdd typically larger than ˜0.01). The observed fraction of absorbed AGN (NH > 1022 cm-2) is around 40 per cent among the total sample, and ˜75 per cent among type 2 AGN. The majority of obscured AGN are narrow-line objects, while unobscured AGN are broad-line objects, obeying to the zeroth-order predictions of unified models. A significant anti-correlation between the radio core dominance parameter and the X-ray column density is found. The observed fraction of Compton thick AGN is ˜2-3 per cent, in comparison with the 5-7 per cent found in radio-quiet hard X-ray selected AGN. We have estimated the absorption and Compton thick fractions in a hard X-ray sample containing both radio galaxies and non-radio galaxies and therefore affected by the same selection biases. No statistical significant difference was found in the absorption properties of radio galaxies and non-radio galaxies sample. In particular, the Compton thick objects are likely missing in both samples and the fraction of obscured radio galaxies appears to decrease with luminosity as observed in hard X-ray non-radio galaxies.

Abell 1033: birth of a radio phoenix

DOE PAGES

de Gasperin, F.; Ogrean, G. A.; van Weeren, R. J.; ...

2015-02-26

We report that extended steep-spectrum radio emission in a galaxy cluster is usually associated with a recent merger. However, given the complex scenario of galaxy cluster mergers, many of the discovered sources hardly fit into the strict boundaries of a precise taxonomy. This is especially true for radio phoenixes that do not have very well defined observational criteria. Radio phoenixes are aged radio galaxy lobes whose emission is reactivated by compression or other mechanisms. Here in this paper, we present the detection of a radio phoenix close to the moment of its formation. The source is located in Abell 1033,more » a peculiar galaxy cluster which underwent a recent merger. To support our claim, we present unpublished Westerbork Synthesis Radio Telescope and Chandra observations together with archival data from the Very Large Array and the Sloan Digital Sky Survey. We discover the presence of two subclusters displaced along the N–S direction. The two subclusters probably underwent a recent merger which is the cause of a moderately perturbed X-ray brightness distribution. A steep-spectrum extended radio source very close to an active galactic nucleus (AGN) is proposed to be a newly born radio phoenix: the AGN lobes have been displaced/compressed by shocks formed during the merger event. This scenario explains the source location, morphology, spectral index, and brightness. Finally, we show evidence of a density discontinuity close to the radio phoenix and discuss the consequences of its presence.« less

A Media Mix Test of Paid Radio Advertising for Armed Services Recruitment. Volume II.

DTIC Science & Technology

1976-05-01

This was a test of the effectiveness of paid radio recruiting advertising . The four active military services (Army, Navy, Air Force, Marine Corps...service, awareness and knowledge of specific programs and benefits offered by individual services and awareness of armed forces advertising . (Author)

A Media MIX Test of Paid Radio Advertising for Armed Services Recruitment. Volume 3. Addendum.

DTIC Science & Technology

1976-07-01

This was a test of the effectiveness of paid radio recruiting advertising . The four active military services (Army, Navy, Air Force, Marine Corps...service, awareness and knowledge of specific programs and benefits offered by individual services and awareness of armed forces advertising . (Author)

Hartebeesthoek Radio Astronomy Observatory (HartRAO)

NASA Technical Reports Server (NTRS)

Nickola, Marisa; Gaylard, Mike; Quick, Jonathan; Combrinck, Ludwig

2013-01-01

HartRAO provides the only fiducial geodetic site in Africa, and it participates in global networks for VLBI, GNSS, SLR, and DORIS. This report provides an overview of geodetic VLBI activities at HartRAO during 2012, including the conversion of a 15-m alt-az radio telescope to an operational geodetic VLBI antenna.

Goldstone radio spectrum protection. [deep space network

NASA Technical Reports Server (NTRS)

Gaudian, B. A.; Cushman, R. B.

1980-01-01

Potential electromagnetic interference to the Goldstone tracking receivers due to neighboring military installations is discussed. Coordination of the military and NASA Goldstone activities in the Mojave Desert area is seen to be an effective method to protect the Goldstone radio spectrum while maintaining compatible operations for the military and Goldstone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Gasperin, F.; Ogrean, G. A.; van Weeren, R. J.

We report that extended steep-spectrum radio emission in a galaxy cluster is usually associated with a recent merger. However, given the complex scenario of galaxy cluster mergers, many of the discovered sources hardly fit into the strict boundaries of a precise taxonomy. This is especially true for radio phoenixes that do not have very well defined observational criteria. Radio phoenixes are aged radio galaxy lobes whose emission is reactivated by compression or other mechanisms. Here in this paper, we present the detection of a radio phoenix close to the moment of its formation. The source is located in Abell 1033,more » a peculiar galaxy cluster which underwent a recent merger. To support our claim, we present unpublished Westerbork Synthesis Radio Telescope and Chandra observations together with archival data from the Very Large Array and the Sloan Digital Sky Survey. We discover the presence of two subclusters displaced along the N–S direction. The two subclusters probably underwent a recent merger which is the cause of a moderately perturbed X-ray brightness distribution. A steep-spectrum extended radio source very close to an active galactic nucleus (AGN) is proposed to be a newly born radio phoenix: the AGN lobes have been displaced/compressed by shocks formed during the merger event. This scenario explains the source location, morphology, spectral index, and brightness. Finally, we show evidence of a density discontinuity close to the radio phoenix and discuss the consequences of its presence.« less

A direct localization of a fast radio burst and its host.

PubMed

Chatterjee, S; Law, C J; Wharton, R S; Burke-Spolaor, S; Hessels, J W T; Bower, G C; Cordes, J M; Tendulkar, S P; Bassa, C G; Demorest, P; Butler, B J; Seymour, A; Scholz, P; Abruzzo, M W; Bogdanov, S; Kaspi, V M; Keimpema, A; Lazio, T J W; Marcote, B; McLaughlin, M A; Paragi, Z; Ransom, S M; Rupen, M; Spitler, L G; van Langevelde, H J

2017-01-04

Fast radio bursts are astronomical radio flashes of unknown physical nature with durations of milliseconds. Their dispersive arrival times suggest an extragalactic origin and imply radio luminosities that are orders of magnitude larger than those of all known short-duration radio transients. So far all fast radio bursts have been detected with large single-dish telescopes with arcminute localizations, and attempts to identify their counterparts (source or host galaxy) have relied on the contemporaneous variability of field sources or the presence of peculiar field stars or galaxies. These attempts have not resulted in an unambiguous association with a host or multi-wavelength counterpart. Here we report the subarcsecond localization of the fast radio burst FRB 121102, the only known repeating burst source, using high-time-resolution radio interferometric observations that directly image the bursts. Our precise localization reveals that FRB 121102 originates within 100 milliarcseconds of a faint 180-microJansky persistent radio source with a continuum spectrum that is consistent with non-thermal emission, and a faint (twenty-fifth magnitude) optical counterpart. The flux density of the persistent radio source varies by around ten per cent on day timescales, and very long baseline radio interferometry yields an angular size of less than 1.7 milliarcseconds. Our observations are inconsistent with the fast radio burst having a Galactic origin or its source being located within a prominent star-forming galaxy. Instead, the source appears to be co-located with a low-luminosity active galactic nucleus or a previously unknown type of extragalactic source. Localization and identification of a host or counterpart has been essential to understanding the origins and physics of other kinds of transient events, including gamma-ray bursts and tidal disruption events. However, if other fast radio bursts have similarly faint radio and optical counterparts, our findings imply that direct subarcsecond localizations may be the only way to provide reliable associations.

Black Hole Demographics in and Nuclear Properties of Nearby Low Luminosity Radio Galaxies; Connections to Radio Activity?

NASA Technical Reports Server (NTRS)

Baum, S. A.; Kleijn, G. A. Verdoes; Xu, C.; ODea, C. P.; deZeeuw, P. T.

2004-01-01

We combine the results of an HST STIS and WFPC study of a complete sample of 21 nearby UGC low luminosity radio galaxies with the results of a radio VLA and VLBA study of the same sample. We examine the relationship between the stellar and gaseous properties of the galaxies on tens to hundreds of parsec scale with the properties of the radio jets on the same scale. From the VLA and VLBA data we constrain the physics of the outflowing radio plasma from the tens of parsecs to hundreds of kiloparsec scales. From the WFPC2 H alpha and dust images and the STIS kinematics of the near nuclear gas we obtain constraints on the orientation of near nuclear disks of gas and measures of the nuclear stellar, continuum point source, and line emission fluxes. Under the statistically supported assumption that the radio jet issues perpendicular to the disk, we use the orientation of the optical (large scale accretion?) disks to constrain the three-dimensional orientation of the radio ejection. From HST/STIS spectroscopy of the near-nuclear emission line gas we obtain measures/limits on the black hole masses. We examine correlations between the VLBA and VLA-scale radio emission, the nuclear line emission, and the nuclear optical and radio continuum emission. Though our sample is relatively small, it is uniquely well defined, spans a narrow range in redshift and we have a consistent set of high resolution data with which to carefully examine these relationships. We use the combined radio and optical data to: 1) Constrain the orientation, physics, and bulk outflow speed of the radio plasma; 2) Put limits on the mass accretion rate and study the relationship between black hole mass, radio luminosity, and near nuclear gaseous content; 3) Provide insight into the relationship between BL Lac objects and low luminosity radio galaxies.

The Gamma-Ray Emitting Radio-Loud Narrow-Line Seyfert 1 Galaxy PKS 2004-447 II. The Radio View

NASA Technical Reports Server (NTRS)

Schulz, R.; Kreikenbohm, A.; Kadler, M.; Ojha, R.; Ros, E.; Stevens, J.; Edwards, P. G.; Carpenter, B.; Elsaesser, D.; Gehrels, N.;

Periodic optical variability of radio-detected ultracool dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harding, L. K.; Golden, A.; Singh, Navtej

2013-12-20

A fraction of very low mass stars and brown dwarfs are known to be radio active, in some cases producing periodic pulses. Extensive studies of two such objects have also revealed optical periodic variability, and the nature of this variability remains unclear. Here, we report on multi-epoch optical photometric monitoring of six radio-detected dwarfs, spanning the ∼M8-L3.5 spectral range, conducted to investigate the ubiquity of periodic optical variability in radio-detected ultracool dwarfs. This survey is the most sensitive ground-based study carried out to date in search of periodic optical variability from late-type dwarfs, where we obtained 250 hr of monitoring,more » delivering photometric precision as low as ∼0.15%. Five of the six targets exhibit clear periodicity, in all cases likely associated with the rotation period of the dwarf, with a marginal detection found for the sixth. Our data points to a likely association between radio and optical periodic variability in late-M/early-L dwarfs, although the underlying physical cause of this correlation remains unclear. In one case, we have multiple epochs of monitoring of the archetype of pulsing radio dwarfs, the M9 TVLM 513–46546, spanning a period of 5 yr, which is sufficiently stable in phase to allow us to establish a period of 1.95958 ± 0.00005 hr. This phase stability may be associated with a large-scale stable magnetic field, further strengthening the correlation between radio activity and periodic optical variability. Finally, we find a tentative spin-orbit alignment of one component of the very low mass binary, LP 349–25.« less

On the radio properties of the intermediate-mass black hole candidate ESO 243-49 HLX-1

NASA Astrophysics Data System (ADS)

Cseh, D.; Webb, N. A.; Godet, O.; Barret, D.; Corbel, S.; Coriat, M.; Falcke, H.; Farrell, S. A.; Körding, E.; Lenc, E.; Wrobel, J. M.

2015-02-01

We present follow-up radio observations of ESO 243-49 HLX-1 from 2012 using the Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large Array (VLA). We report the detection of radio emission at the location of HLX-1 during its hard X-ray state using the ATCA. Assuming that the `Fundamental Plane' of accreting black holes is applicable, we provide an independent estimate of the black hole mass of M_{BH}≤ 2.8^{+7.5}_{-2.1} × 106 M⊙ at 90 per cent confidence. However, we argue that the detected radio emission is likely to be Doppler-boosted and our mass estimate is an upper limit. We discuss other possible origins of the radio emission such as being due to a radio nebula, star formation, or later interaction of the flares with the large-scale environment. None of these were found adequate. The VLA observations were carried out during the X-ray outburst. However, no new radio flare was detected, possibly due to a sparse time sampling. The deepest, combined VLA data suggest a variable radio source and we briefly discuss the properties of the previously detected flares and compare them with microquasars and active galactic nuclei.

The Identification of EGRET Sources with Flat-Spectrum Radio Sources

NASA Astrophysics Data System (ADS)

Mattox, J. R.; Schachter, J.; Molnar, L.; Hartman, R. C.; Patnaik, A. R.

1997-05-01

We present a method to assess the reliability of the identification of EGRET sources with extragalactic radio sources. We verify that EGRET is detecting the blazar class of active galactic nuclei (AGNs). However, many published identifications are found to be questionable. We provide a table of 42 blazars that we expect to be robust identifications of EGRET sources. This includes one previously unidentified EGRET source, the lensed AGN PKS 1830-210, near the direction of the Galactic center. We provide the best available positions for 16 more radio sources that are also potential identifications for previously unidentified EGRET sources. All high Galactic latitude EGRET sources (|b| > 3°) that demonstrate significant variability can be identified with flat-spectrum radio sources. This suggests that EGRET is not detecting any type of AGN other than blazars. This identification method has been used to establish with 99.998% confidence that the peak γ-ray flux of a blazar is correlated with its average 5 GHz radio flux. An even better correlation is seen between γ-ray flux and the 2.29 GHz flux density measured with VLBI at the base of the radio jet. Also, using high-confidence identifications, we find that the radio sources identified with EGRET sources have greater correlated VLBI flux densities than the parent population of flat radio spectrum sources.

THE {gamma}-RAY EMISSION REGION IN THE FANAROFF-RILEY II RADIO GALAXY 3C 111

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grandi, P.; Torresi, E.; Stanghellini, C., E-mail: grandi@iasfbo.inaf.it, E-mail: torresi@iasfbo.inaf.it, E-mail: cstan@ira.inaf.it

The broad-line radio galaxy 3C 111, characterized by a Fanaroff-Riley II (FRII) radio morphology, is one of the sources of the misaligned active galactic nucleus sample, consisting of radio galaxies and steep spectrum radio quasars, recently detected by the Fermi Large Area Telescope (LAT). Our analysis of the 24 month {gamma}-ray light curve shows that 3C 111 was only occasionally detected at high energies. It was bright at the end of 2008 and faint, below the Fermi-LAT sensitivity threshold, for the rest of the time. A multifrequency campaign of 3C 111, ongoing in the same period, revealed an increase ofmore » the millimeter, optical, and X-ray fluxes in 2008 September-November, interpreted by Chatterjee et al. as due to the passage of a superluminal knot through the jet core. The temporal coincidence of the millimeter-optical-X-ray outburst with the GeV activity suggests a cospatiality of the events, allowing, for the first time, the localization of the {gamma}-ray dissipative zone in an FRII jet. We argue that the GeV photons of 3C 111 are produced in a compact region confined within 0.1 pc and at a distance of about 0.3 pc from the black hole.« less

Tuning Into Brown Dwarfs: Long-Term Radio Monitoring of Two Very Low Mass Dwarfs

NASA Astrophysics Data System (ADS)

Van Linge, Russell; Burgasser, Adam J.; Melis, Carl; Williams, Peter K. G.

2017-01-01

The very lowest-mass (VLM) stars and brown dwarfs, with effective temperatures T < 3000 K, exhibit mixed magnetic activity trends, with H-alpha and X-ray emission that declines rapidly beyond type M7/M8, but persistent radio emission in roughly 10-20% of sources. The dozen or so VLM radio emitters known show a broad range of emission characteristics and time-dependent behavior, including steady persistent emission, periodic oscillations, periodic polarized bursts, and aperiodic flares. Understanding the evolution of these variability patterns, and in particular whether they undergo solar-like cycles, requires long-term monitoring. We report the results of a long-term JVLA monitoring program of two magnetically-active VLM dwarf binaries, the young M7 2MASS 1314+1320AB and older L5 2MASS 1315-2649AB. On the bi-weekly cadence, 2MASS 1314 continues to show variability by revealing regular flaring while 2MASS 1315 continues to be a quiescent emitter. On the daily time scale, both sources show a mean flux density that can vary significantly just over a few days. These results suggest long-term radio behavior in radio-emitting VLM dwarfs is just as diverse and complex as short-term behavior.

Red Geyser: A New Class of Galaxy with Large-scale AGN-driven Winds

NASA Astrophysics Data System (ADS)

Roy, Namrata; Bundy, Kevin; Cheung, Edmond; MaNGA Team

2018-01-01

A new class of quiescent (non-star-forming) galaxies harboring possible AGN-driven winds have been discovered using the spatially resolved optical spectroscopy from the ongoing SDSS-IV MaNGA (Sloan Digital Sky Survey-IV Mapping Nearby Galaxies at Apache Point Observatory) survey. These galaxies named "red geysers" constitute 5%-10% of the local quiescent galaxy population and are characterized by narrow bisymmetric ionized gas emission patterns. These enhanced patterns are seen in equivalent width maps of Hα, [OIII] and other strong emission lines. They are co-aligned with the ionized gas velocity gradients but significantly misaligned with stellar velocity gradients. They also show very high gas velocity dispersions (~200 km/s). Considering these observations in light of models of the gravitational potential, Cheung et al. argued that red geysers host large-scale AGN-driven winds of ionized gas that may play a role in suppressing star formation at late times. In this work, we test the hypothesis that AGN activity is ultimately responsible for the red geyser phenomenon. We compare the nuclear radio activity of the red geysers to a matched control sample of galaxies of similar stellar mass, redshift, rest frame NUV–r color and axis ratio. and additionally, control for the presence of ionized gas. We have used 1.4 GHz radio continuum data from the VLA FIRST Survey to stack the radio flux from the red geyser sample and control sample. We find that the red geysers have a higher average radio flux than the control galaxies at > 3σ significance. Our sample is restricted to rest-frame NUV–r color > 5, thus ruling out possible radio emission due to star formation activity. We conclude that red geysers are associated with more active AGN, supporting a feedback picture in which episodic AGN activity drives large-scale but relatively weak ionized winds in many in many early-type galaxies.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1994-01-01

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC). The TDA Office also performs work funded by other NASA program offices through and with the cooperation of OSC. Finally, tasks funded under the JPL Director's Discretionary Fund and the Caltech President's Fund that involve the TDA Office are included.

A periodically active pulsar giving insight into magnetospheric physics.

PubMed

Kramer, M; Lyne, A G; O'Brien, J T; Jordan, C A; Lorimer, D R

2006-04-28

PSR B1931+24 (J1933+2421) behaves as an ordinary isolated radio pulsar during active phases that are 5 to 10 days long. However, when the radio emission ceases, it switches off in less than 10 seconds and remains undetectable for the next 25 to 35 days, then switches on again. This pattern repeats quasi-periodically. The origin of this behavior is unclear. Even more remarkably, the pulsar rotation slows down 50% faster when it is on than when it is off. This indicates a massive increase in magnetospheric currents when the pulsar switches on, proving that pulsar wind plays a substantial role in pulsar spin-down. This allows us, for the first time, to estimate the magnetospheric currents in a pulsar magnetosphere during the occurrence of radio emission.

VLA Detects Unexplained Radio Emission From Three Brown Dwarfs

NASA Astrophysics Data System (ADS)

2005-01-01

Astronomers have discovered three brown dwarfs -- enigmatic objects that are neither stars nor planets -- emitting radio waves that scientists cannot explain. The three newly-discovered radio-emitting brown dwarfs were found as part of a systematic study of nearby brown dwarfs using the National Science Foundation's Very Large Array (VLA) radio telescope. The VLA The Very Large Array CREDIT: NRAO/AUI/NSF (Click on image for VLA gallery) Until 2001, scientists believed that brown dwarfs, which are intermediate in mass between stars and planets, could not emit detectable amounts of radio waves. That year, summer students at the VLA made the first discovery of radio emission from a brown dwarf. Subsequently, as many as a half- dozen more radio-emitting brown dwarfs were discovered. "It clearly had become time to make a systematic study and try to find out just what percentage of brown dwarfs are emitting radio waves," said Rachel Osten, an astronomer at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia. Osten was assisted in the project in the summer of 2004 by Lynnae Quick, a student at North Carolina Agricultural and Technical State University; Tim Bastian, also an astronomer at NRAO; and Suzanne Hawley, an astronomer at the University of Washington. The research team presented their results to the American Astronomical Society's meeting in San Diego, CA. The three new detections of radio-emitting brown dwarfs are just the first results from the systematic study, which aims to observe all the known brown dwarfs within about 45 light-years of Earth. "We want to be able to say definitively just how common radio emission is among brown dwarfs," Osten explained. The study involves observing 65 individual brown dwarfs, so these new detections represent just the beginning of the results expected from the study. Brown dwarfs are too big to be planets but too small to be true stars, as they have too little mass to trigger hydrogen fusion reactions at their cores, the source of the energy output in larger stars. With roughly 15 to 80 times the mass of Jupiter, the largest planet in our Solar System, brown dwarfs had long been thought to exist, but proved difficult to find. Astronomers found the first brown dwarf in 1995, and a few hundred now are known. The type of radio emission seen in the brown dwarfs arises in more-massive stars as a result of plasma interacting with the star's magnetic field. However, astronomers have noted that this type of activity declines in less-massive stars. This is why they expected brown dwarfs, with masses less than that of any star, to lack radio emission. Surprisingly, based on discoveries since 2001, it now appears that radio-emitting magnetic activity may actually become more common in these very low-mass objects. "We don't have an explanation for this," Osten said. The scientists hope that brown-dwarf radio emission may give them a new tool for analysis. "Since both stars and the planets in our Solar System produce radio emission, detailed study of the radio emission properties of these brown dwarfs may enable us to distinguish where the boundary between stellar and planetary behavior occurs in these not-quite-stars, not-quite-planets," Osten explained. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

A strong radio brightening at the jet base of M 87 during the elevated very high energy gamma-ray state in 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hada, K.; Giroletti, M.; Giovannini, G.

2014-06-20

We report our intensive, high angular resolution radio monitoring observations of the jet in M 87 with the VLBI Exploration of Radio Astrometry (VERA) and the European VLBI Network (EVN) from 2011 February to 2012 October, together with contemporaneous high-energy (100 MeV 100 GeV) γ rays by VERITAS. We detected a remarkable (up to ∼70%) increase of the radio flux density from the unresolved jet base (radio core) with VERA at 22 and 43 GHz coincident with the VHE activity. Meanwhile, we confirmed with EVN at 5 GHz that the peculiar knot, HST-1, which is an alternative favored γ-ray productionmore » site located at ≳120 pc from the nucleus, remained quiescent in terms of its flux density and structure. These results in the radio bands strongly suggest that the VHE γ-ray activity in 2012 originates in the jet base within 0.03 pc or 56 Schwarzschild radii (the VERA spatial resolution of 0.4 mas at 43 GHz) from the central supermassive black hole. We further conducted VERA astrometry for the M 87 core at six epochs during the flaring period, and detected core shifts between 22 and 43 GHz, a mean value of which is similar to that measured in the previous astrometric measurements. We also discovered a clear frequency-dependent evolution of the radio core flare at 43, 22, and 5 GHz; the radio flux density increased more rapidly at higher frequencies with a larger amplitude, and the light curves clearly showed a time-lag between the peaks at 22 and 43 GHz, the value of which is constrained to be within ∼35-124 days. This indicates that a new radio-emitting component was created near the black hole in the period of the VHE event, and then propagated outward with progressively decreasing synchrotron opacity. By combining the obtained core shift and time-lag, we estimated an apparent speed of the newborn component propagating through the opaque region between the cores at 22 and 43 GHz. We derived a sub-luminal speed (less than ∼0.2c) for this component. This value is significantly slower than the super-luminal (∼1.1c) features that appeared from the core during the prominent VHE flaring event in 2008, suggesting that stronger VHE activity can be associated with the production of a higher Lorentz factor jet in M 87.« less

THE ABSENCE OF RADIO EMISSION FROM THE GLOBULAR CLUSTER G1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller-Jones, J. C. A.; Wrobel, J. M.; Sivakoff, G. R.

2012-08-10

The detections of both X-ray and radio emission from the cluster G1 in M31 have provided strong support for existing dynamical evidence for an intermediate-mass black hole (IMBH) of mass (1.8 {+-} 0.5) Multiplication-Sign 10{sup 4} M{sub Sun} at the cluster center. However, given the relatively low significance and astrometric accuracy of the radio detection, and the non-simultaneity of the X-ray and radio measurements, this identification required further confirmation. Here we present deep, high angular resolution, strictly simultaneous X-ray and radio observations of G1. While the X-ray emission (L{sub X} = 1.74{sup +0.53}{sub -0.44} Multiplication-Sign 10{sup 36} (d/750 kpc){sup 2}more » erg s{sup -1} in the 0.5-10 keV band) remained fully consistent with previous observations, we detected no radio emission from the cluster center down to a 3{sigma} upper limit of 4.7 {mu}Jy beam{sup -1}. Our favored explanation for the previous radio detection is flaring activity from a black hole low-mass X-ray binary (LMXB). We performed a new regression of the 'Fundamental Plane' of black hole activity, valid for determining black hole mass from radio and X-ray observations of sub-Eddington black holes, finding log M{sub BH} = (1.638 {+-} 0.070)log L{sub R} - (1.136 {+-} 0.077)log L{sub X} - (6.863 {+-} 0.790), with an empirically determined uncertainty of 0.44 dex. This constrains the mass of the X-ray source in G1, if a black hole, to be <9.7 Multiplication-Sign 10{sup 3} M{sub Sun} at 95% confidence, suggesting that it is a persistent LMXB. This annuls what was previously the most convincing evidence from radiation for an IMBH in the Local Group, though the evidence for an IMBH in G1 from velocity dispersion measurements remains unaffected by these results.« less

VLA observations of a complete sample of extragalactic X-ray sources. II

NASA Technical Reports Server (NTRS)

Schild, R.; Zamorani, G.; Gioia, I. M.; Feigelson, E. D.; Maccacaro, T.

1983-01-01

A complete sample of 35 X-ray selected sources found with the Einstein Observatory has been observed with the Very Large Array at 6 cm to investigate the relationship between radio and X-ray emission in extragalactic objects. Detections include three active galactic nuclei (AGNs), two clusters or groups of galaxies, two individual galaxies, and two BL Lac objects. The frequency of radio emission in X-ray selected AGNs is compared with that of optically selected quasars using the integral radio-optical luminosity function. The result suggests that the probability for X-ray selected quasars to be radio sources is higher than for those optically selected. No obvious correlation is found in the sample between the richness of X-ray luminosity of the cluster and the presence of a galaxy with radio luminosity at 5 GHz larger than 10 to the 30th ergs/s/Hz.

Radioelectronics and space exploration

NASA Astrophysics Data System (ADS)

Sarafanov, T.; Bogoroditskiy, Y.; Milyukov, I.

1985-03-01

Citing the 23 years since Yuriy Gagarin's first radio transmission from outer space, the developments in radio communications and their role in mission control are summarized. Use of satellites for radio and television links with ground stations are an important part of information exchange. Construction and preventive maintenance activities by Soviet cosmonauts, use of radio technology for docking procedures and the reliability of such equipment, and the growing role of computer technology in space vehicles with human crews and pilotless craft are discussed. Automatic interplanetary vehicles that have landed on the moon, Mars and Venus, as well as artificial earth satellites, are facilitating weather and communication advances. Mock space equipment using radio and computer technology is of great importance for training cosmonauts. Despite all these practical applications, optimum utilization of automated equipment has yet to be achieved, and offers further challenge to Soviet and other engineers and technicians.

A Case for Radio Galaxies as the Sources of IceCube's Astrophysical Neutrino Flux

DOE PAGES

Hooper, Dan

2016-09-01

Here, we present an argument that radio galaxies (active galaxies with mis-aligned jets) are likely to be the primary sources of the high-energy astrophysical neutrinos observed by IceCube. In particular, if the gamma-ray emission observed from radio galaxies is generated through the interactions of cosmic-ray protons with gas, these interactions can also produce a population of neutrinos with a flux and spectral shape similar to that measured by IceCube. We present a simple physical model in which high-energy cosmic rays are confined within the volumes of radio galaxies, where they interact with gas to generate the observed diffuse fluxes ofmore » neutrinos and gamma rays. In addition to simultaneously accounting for the observations of Fermi and IceCube, radio galaxies in this model also represent an attractive class of sources for the highest energy cosmic rays.« less

Effects of the 2017 Solar Eclipse on HF Radio Propagation and the D-Region Ionosphere: Citizen Science Investigation

NASA Technical Reports Server (NTRS)

Fry, C. D.; Rawlins, L.; Krause, L. H.; Suggs, R. M.; McTernan, J. K.; Adams, M. L.; Gallagher, D. L.; Anderson, Scott; Allsbrooks, Robert IV

2017-01-01

August 21, 2017 provided a unique opportunity to investigate the effects of the total solar eclipse on high frequency (HF) radio propagation and ionospheric variability. In Marshall Space Flight Center's partnership with the US Space and Rocket Center (USSRC) and Austin Peay State University (APSU), we engaged students and citizen scientists in an investigation of the eclipse effects on the mid-latitude ionosphere. Activities included implementing and configuring software, monitoring the HF Amateur Radio frequency bands and collecting radio transmission data on days before, the day of, and days after the eclipse to build a continuous record of changing propagation conditions as the moon's shadow marched across the United States. Post-eclipse radio propagation analysis provided insights into ionospheric variability due to the eclipse. We report on results, interpretation, and conclusions of these investigations.

Physics of the Solar Active Regions from Radio Observations

NASA Astrophysics Data System (ADS)

Gelfreikh, G. B.

1999-12-01

Localized increase of the magnetic field observed by routine methods on the photosphere result in the growth of a number of active processes in the solar atmosphere and the heliosphere. These localized regions of increased magnetic field are called active regions (AR). The main processes of transfer, accumulation and release of energy in an AR is, however, out of scope of photospheric observations being essentially a 3D-process and happening either under photosphere or up in the corona. So, to investigate these plasma structures and processes we are bound to use either extrapolation of optical observational methods or observations in EUV, X-rays and radio. In this review, we stress and illustrate the input to the problem gained from radio astronomical methods and discuss possible future development of their applicatications. Historically speaking each new step in developing radio technique of observations resulted in detecting some new physics of ARs. The most significant progress in the last few years in radio diagnostics of the plasma structures of magnetospheres of the solar ARs is connected with the developing of the 2D full disk analysis on regular basis made at Nobeyama and detailed multichannel spectral-polarization (but one-dimensional and one per day) solar observations at the RATAN-600. In this report the bulk of attention is paid to the new approach to the study of solar activity gained with the Nobeyama radioheliograph and analyzing the ways for future progress. The most important new features of the multicomponent radio sources of the ARs studied using Nobeyama radioheliograph are as follow: 1. The analysis of magnetic field structures in solar corona above sunspot with 2000 G. Their temporal evolution and fluctuations with the periods around 3 and 5 minutes, due to MHD-waves in sunspot magnetic tubes and surrounding plasma. These investigations are certainly based on an analysis of thermal cyclotron emission of lower corona and CCTR above sunspot umbra. 2. Magnetography of the solar active regions presenting the weak magnetic fields (with the sensitivity of several G) reflecting longitude component of the magnetic field in chromosphere and corona and solar faculae structure. The method is based on an analysis of the weak polarization (of the order of 1% or less). 3. An analysis of the structure, temperature, and density of arches seen above neutral magnetic field lines (seen in most ARs with spots and without ones). 4. Study of temporal and spatial behavior of inversion of the sign of the circular polarization with the result of magnetography of the solar corona. 5. An analysis of the solar activity at high heliographic latitudes, observed mostly as polar faculae (increased brightness structures having counterparts in optical white light observations). In modern study of the solar activity analysis of the activity of polar zones are of principal importance. Nobeyama probably presents the most reliable way to study this. The above points present not exactly completed results but rather the directions for future studies. These should use full time coverage of observations at different phases of the solar activity and combination of observations with other radio, optical, EUV and X-ray observations whenever possible.

Fermi LAT detection of an increase of gamma-ray activity of S5 1044+71

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2014-01-01

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar S5 1044+71 (also known as 2FGL J1048.3+7144, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 162.1150829 deg, Dec: 71.7266494 deg (J2000; Johnston et al. 1995, AJ, 110, 880) at redshift z=1.15 (Polatidis et al.

Fermi LAT detection of a continuing increase of gamma-ray activity of CTA 102

NASA Astrophysics Data System (ADS)

Orienti, M.; D'Ammando, F.

2012-09-01

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar CTA 102 (also known as 2FGL J2232.4+1143, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 338.1517038 deg, Dec: 11.7308067 deg (J2000, Johnston et al. 1995, AJ, 110, 880) at redshift z=1.037 (Schmidt 1965, ApJ, 141, 1295).

Stellar Dynamics and Star Formation Histories of z ∼ 1 Radio-loud Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barišić, Ivana; Van der Wel, Arjen; Chauké, Priscilla

We investigate the stellar kinematics and stellar populations of 58 radio-loud galaxies of intermediate luminosities ( L {sub 3} {sub GHz} > 10{sup 23} W Hz{sup −1}) at 0.6 < z < 1. This sample is constructed by cross-matching galaxies from the deep VLT/VIMOS LEGA-C spectroscopic survey with the VLA 3 GHz data set. The LEGA-C continuum spectra reveal for the first time stellar velocity dispersions and age indicators of z ∼ 1 radio galaxies. We find that z ∼ 1 radio-loud active galactic nucleus (AGN) occur exclusively in predominantly old galaxies with high velocity dispersions: σ {sub *} >more » 175 km s{sup −1}, corresponding to black hole masses in excess of 10{sup 8} M {sub ⊙}. Furthermore, we confirm that at a fixed stellar mass the fraction of radio-loud AGN at z ∼ 1 is five to 10 times higher than in the local universe, suggesting that quiescent, massive galaxies at z ∼ 1 switch on as radio AGN on average once every Gyr. Our results strengthen the existing evidence for a link between high black hole masses, radio loudness, and quiescence at z ∼ 1.« less

SBS 0846+513: a New Gamma-ray Emitting Narrow-line Seyfert 1 Galaxy

NASA Technical Reports Server (NTRS)

D'Ammando, F.; Orienti, M.; Finke, J.; Raiteri, C. M.; Angelakis, E.; Fuhrmann, L.; Giroletti, M.; Hovatta, T.; Max-Moerbeck, W.; Perkins, J. S.;

The Spotted Active Binary UX Arietis

NASA Astrophysics Data System (ADS)

Hummel, Christian

2018-04-01

UX Arietis is one of the most active members of the RS CVn class of binaries in which spin-up of a sub-giant/giant star by a close companion led to the creation of magnetic fields which in turn are responsible for the radio and X-ray flares of UX Ariestis as well as its photometric variability. We observed this binary with the MIRC beam combiner at the CHARA array and made images of a single large spot rotating in and out of view over a month in 2012. A precise orbit was derived using the Wilson-Devinney code to account for the effect of the spot on the measured visibilities. Archival and new radial velocities taken at the NOT were also corrected for spot activity and allowed us to determine precise stellar masses and luminosities for the components. Consistency with the predicted locations in the HR-diagram is achieved after a careful analysis of the effect of spots. The orbit can be used to establish the relative locations of the stellar components at times when radio observations by Ros and Massi (2007) with the VLBA detected two radio components moving around each other. We tentatively conclude that radio emission in UX Arietis flows along magnetic flux tubes between the stars.

Solar--geophysical data. Prompt reports. [Number 405, May 1978. Data for A/pril 1978--March 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coffey, H.E.

1978-05-01

This prompt report provides data for April 1978 on alert period, daily solar indices, solar flares, solar radio waves, solar x-ray radiation, coronal holes, inferred IP magnetic field polarities, mean solar magnetic field, solar wind measurements, geomagnetic substorms, and magnetograms of geomagnetic storm. It also provides data for March 1978 on daily solar activity center, sudden ionospheric disturbances, solar x-ray radiation, solar radio waves, cosmic rays, geomagnetic indices and radio propagation indices. A new data page lists the North American magnetometer network.

Effect exerted by a radio wave electromagnetic field on the rheological properties of water and portland-cement systems

NASA Astrophysics Data System (ADS)

Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Koshevar, V. D.; Shkadretsova, V. G.; Goncharik, S. V.; Chubrik, N. I.; Orlovich, A. I.

2013-09-01

We have studied the effect of the regimes of high-frequency (radio wave) electromagnetic treatment of gauging water on the process of structurization and on the technological characteristics of portland-cement systems. It has been established that the radio wave electromagnetic activation of water leads to a reduction in its surface tension, dynamic viscosity, and shear stress, as well as intensifies the formation of coagulation structures in a portlandcement slurry and aids in increasing the mobility of cement-sand mixtures.

A luminous hot accretion flow in the low-luminosity active galactic nucleus NGC 7213

NASA Astrophysics Data System (ADS)

Xie, Fu-Guo; Zdziarski, Andrzej A.; Ma, Renyi; Yang, Qi-Xiang

2016-12-01

The active galactic nucleus (AGN) NGC 7213 shows a complex correlation between the monochromatic radio luminosity LR and the 2-10 keV X-ray luminosity LX, I.e. the correlation is unusually weak with p ˜ 0 (in the form L_R∝ L_X^p) when LX is below a critical luminosity, and steep with p > 1 when LX is above that luminosity. Such a hybrid correlation in individual AGNs is unexpected as it deviates from the Fundamental Plane of AGN activity. Interestingly, a similar correlation pattern is observed in the black hole X-ray binary H1743-322, where it has been modelled by switching between different modes of accretion. We propose that the flat LR-LX correlation of NGC 7213 is due to the presence of a luminous hot accretion flow, an accretion model whose radiative efficiency is sensitive to the accretion rate. Given the low luminosity of the source, LX ˜ 10-4 of the Eddington luminosity, the viscosity parameter is determined to be small, α ≈ 0.01. We also modelled the broad-band spectrum from radio to γ-rays, the time lag between the radio and X-ray light curves, and the implied size and the Lorentz factor of the radio jet. We predict that NGC 7213 will enter into a two-phase accretion regime when LX ≳ 1.5 × 1042 erg s- 1. When this happens, we predict a softening of the X-ray spectrum with the increasing flux and a steep radio/X-ray correlation.

Infrared-faint radio sources in the SERVS deep fields. Pinpointing AGNs at high redshift

NASA Astrophysics Data System (ADS)

Maini, A.; Prandoni, I.; Norris, R. P.; Spitler, L. R.; Mignano, A.; Lacy, M.; Morganti, R.

2016-12-01

Context. Infrared-faint radio sources (IFRS) represent an unexpected class of objects which are relatively bright at radio wavelength, but unusually faint at infrared (IR) and optical wavelengths. A recent and extensive campaign on the radio-brightest IFRSs (S1.4 GHz≳ 10 mJy) has provided evidence that most of them (if not all) contain an active galactic nuclei (AGN). Still uncertain is the nature of the radio-faintest IFRSs (S1.4 GHz≲ 1 mJy). Aims: The scope of this paper is to assess the nature of the radio-faintest IFRSs, testing their classification and improving the knowledge of their IR properties by making use of the most sensitive IR survey available so far: the Spitzer Extragalactic Representative Volume Survey (SERVS). We also explore how the criteria of IFRSs can be fine-tuned to pinpoint radio-loud AGNs at very high redshift (z > 4). Methods: We analysed a number of IFRS samples identified in SERVS fields, including a new sample (21 sources) extracted from the Lockman Hole. 3.6 and 4.5 μm IR counterparts of the 64 sources located in the SERVS fields were searched for and, when detected, their IR properties were studied. Results: We compared the radio/IR properties of the IR-detected IFRSs with those expected for a number of known classes of objects. We found that IR-detected IFRSs are mostly consistent with a mixture of high-redshift (z ≳ 3) radio-loud AGNs. The faintest ones (S1.4 GHz 100 μJy), however, could be also associated with nearer (z 2) dust-enshrouded star-burst galaxies. We also argue that, while IFRSs with radio-to-IR ratios >500 can very efficiently pinpoint radio-loud AGNs at redshift 2 < z < 4, lower radio-to-IR ratios ( 100-200) are expected for higher redshift radio-loud AGNs.

CURIE: Cubesat Radio Interferometry Experiment

NASA Astrophysics Data System (ADS)

Sundkvist, D. J.; Saint-Hilaire, P.; Bain, H. M.; Bale, S. D.; Bonnell, J. W.; Hurford, G. J.; Maruca, B.; Martinez Oliveros, J. C.; Pulupa, M.

2016-12-01

The CUbesat Radio Interferometry Experiment (CURIE) is a proposed two-element radio interferometer, based on proven and developed digital radio receivers and designed to fit within a Cubesat platform. CURIE will launch as a 6U Cubesat and then separate into two 3U Cubesats once in orbit. CURIE measures radio waves from 0.1-19MHz, which must be measured from space, as those frequencies fall below the cutoff imposed by Earth's ionosphere. The principal science objective for CURIE is to use radio interferometry to study radio burst emissions from solar eruptive events such as flares and coronal mass ejections (CMEs) in the inner heliosphere, providing observations important for our understanding of the heliospheric space weather environment. The influence of space weather can be felt at Earth and other planets, as radiation levels increase and lead to auroral activity and geomagnetic effects. CURIE will be able to determine the location and size of radio burst source regions and then to track their movement outward from the Sun. In addition to the primary objective CURIE will measure the gradients of the local ionospheric density and electron temperature on the spatial scale of a few kilometers, as well as create an improved map of the radio sky at these unexplored frequencies. A space based radio interferometry observatory has long been envisioned, in orbit around the Earth or the Moon, or on the far side of the Moon. Beyond its important science objectives, CURIE will prove that the concept of a dedicated space-based interferometer can be realized by using relatively cheap Cubesats. CURIE will therefore not only provide new important science results but also serve as a pathfinder in the development of new space-based radio observation techniques for helio- and astro-physics.

FR-type radio sources in COSMOS: relation of radio structure to size, accretion modes and large-scale environment

NASA Astrophysics Data System (ADS)

Vardoulaki, Eleni; Faustino Jimenez Andrade, Eric; Delvecchio, Ivan; Karim, Alexander; Smolčić, Vernesa; Magnelli, Benjamin; Bertoldi, Frank; Schinnener, Eva; Sargent, Mark; Finoguenov, Alexis; VLA COSMOS Team

2018-01-01

The radio sources associated with active galactic nuclei (AGN) can exhibit a variety of radio structures, from simple to more complex, giving rise to a variety of classification schemes. The question which still remains open, given deeper surveys revealing new populations of radio sources, is whether this plethora of radio structures can be attributed to the physical properties of the host or to the environment. Here we present an analysis on the radio structure of radio-selected AGN from the VLA-COSMOS Large Project at 3 GHz (JVLA-COSMOS; Smolčić et al.) in relation to: 1) their linear projected size, 2) the Eddington ratio, and 3) the environment their hosts lie within. We classify these as FRI (jet-like) and FRII (lobe-like) based on the FR-type classification scheme, and compare them to a sample of jet-less radio AGN in JVLA-COSMOS. We measure their linear projected sizes using a semi-automatic machine learning technique. Their Eddington ratios are calculated from X-ray data available for COSMOS. As environmental probes we take the X-ray groups (hundreds kpc) and the density fields (~Mpc-scale) in COSMOS. We find that FRII radio sources are on average larger than FRIs, which agrees with literature. But contrary to past studies, we find no dichotomy in FR objects in JVLA-COSMOS given their Eddington ratios, as on average they exhibit similar values. Furthermore our results show that the large-scale environment does not explain the observed dichotomy in lobe- and jet-like FR-type objects as both types are found on similar environments, but it does affect the shape of the radio structure introducing bents for objects closer to the centre of an X-ray group.

Session 21.3 - Radio and Optical Site Protection

NASA Astrophysics Data System (ADS)

Sefako, Ramotholo

2016-10-01

Advancement in radio technology means that radio astronomy has to share the radio spectrum with many other non-astronomical activities, majority of which increase radio frequency interference (RFI), and therefore detrimentally affecting the radio observations at the observatory sites. Major radio facilities such as the SKA, in both South Africa and Australia, and the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China will be very sensitive, and therefore require protection against RFI. In the case of optical astronomy, the growing urbanisation and industrialisation led to optical astronomy becoming impossible near major cities due to light and dust pollution. Major optical and IR observatories are forced to be far away in remote areas, where light pollution is not yet extreme. The same is true for radio observatories, which have to be sited away from highly RFI affected areas near populated regions and major cities. In this review, based on the Focus Meeting 21 (FM21) oral presentations at the IAU General Assembly on 11 August 2015, we give an overview of the mechanisms that have evolved to provide statutory protection for radio astronomy observing, successes (e.g at 21 cm HI line), defeats and challenges at other parts of the spectrum. We discuss the available legislative initiatives to protect the radio astronomy sites for large projects like SKA (in Australia and South Africa), and FAST against the RFI. For optical protection, we look at light pollution with examples of its effect at Xinglong observing station of the National Astronomical Observatories of China (NAOC), Ali Observatory in Tibet, and Asiago Observatory in Italy, as well as the effect of conversion from low pressure sodium lighting to LEDs in the County of Hawaii.

Radio-loudness in black hole transients: evidence for an inclination effect

NASA Astrophysics Data System (ADS)

Motta, S. E.; Casella, P.; Fender, R.

2018-06-01

Accreting stellar-mass black holes appear to populate two branches in a radio:X-ray luminosity plane. We have investigated the X-ray variability properties of a large number of black hole low-mass X-ray binaries, with the aim of unveiling the physical reasons underlying the radio-loud/radio-quiet nature of these sources, in the context of the known accretion-ejection connection. A reconsideration of the available radio and X-ray data from a sample of black hole X-ray binaries confirms that being radio-quiet is the more normal mode of behaviour for black hole binaries. In the light of this we chose to test, once more, the hypothesis that radio loudness could be a consequence of the inclination of the X-ray binary. We compared the slope of the `hard-line' (an approximately linear correlation between X-ray count rate and rms variability, visible in the hard states of active black holes), the orbital inclination, and the radio-nature of the sources of our sample. We found that high-inclination objects show steeper hard-lines than low-inclination objects, and tend to display a radio-quiet nature (with the only exception of V404 Cyg), as opposed to low-inclination objects, which appear to be radio-loud(er). While in need of further confirmation, our results suggest that - contrary to what has been believed for years - the radio-loud/quiet nature of black-hole low mass X-ray binaries might be an inclination effect, rather than an intrinsic source property. This would solve an important issue in the context of the inflow-outflow connection, thus providing significant constraints to the models for the launch of hard-state compact jets.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1987-01-01

This quarterly publication (July-September 1987) provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio astronomy, it reports on activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, in supporting research and technology, in implementation, and in operations. This work is performed for NASA's Office of Space Tracking and Data Systems (OSTDS). In geodynamics, the publication reports on the application of radio interferometry at microwave frequencies for geodynamic measurements. In the Search for Extraterrestrial Intelligence (SETI), it reports on implementation and operations for searching the microwave spectrum. The latter two programs are performed for NASA's Office of Space Science and Applications (OSSA).

Multiband observations of Cygnus A: A study of pressure balance in the core of a powerful radio galaxy

NASA Technical Reports Server (NTRS)

Carilli, Chris; Conner, Sam; Dreher, John; Perley, Rick

1990-01-01

Cygnus A is a powerful double radio source associated with a giant elliptical galaxy at the center of a poor cluster of galaxies. The radio source also sits within the core radius of a dense, cooling flow, x ray emitting cluster gas. Optical spectroscopy and narrow band imaging have revealed copious amounts of narrow line emission from the inner 20 kpc of the associated galaxy. Researchers assume H sub o = 75 km sec (-1) Mpc(-1). Discussed here are the pressures in the three components of the Interstellar Medium (ISM) (i.e., the radio, x ray, and line emitting fluids) within a radius of about 15 kpc of the active nucleus of the Cygnus A galaxy.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1986-01-01

This quarterly publication (July-Sept. 1986) provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio astronomy, it reports on activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, in supporting research and technology, in implementation, and in operations. This work is performed for NASA's Office of Space Tracking and Data Systems (OSTDS). In geodynamics, the publication reports on the application of radio interferometry at microwave frequencies for geodynamic measurements. In the search for extraterrestrial intelligence (SETI), it reports on implementation and operations for searching the microwave spectrum. The latter two programs are performed for NASA's Office of Space Science and Applications (OSSA).

Arduino Based Weather Monitoring Telemetry System Using NRF24L01+

NASA Astrophysics Data System (ADS)

Sidqi, Rafi; Rio Rynaldo, Bagus; Hadi Suroso, Satya; Firmansyah, Rifqi

2018-04-01

Abstract-Weather is an important part of the natural environment, thus knowing weather information is needed before doing activity. The main purpose of this research was to develop a weather monitoring system which capable to transmit weather data via radio frequency by using nRF24L01+ 2,4GHz radio module. This research implement Arduino UNO as the main controller of the system which send data wirelessly using the radio module and received by a receiver system. Received data then logged and displayed using a Graphical User Interface on a personal computer. Test and experiment result show that the system was able to transmit weather data via radio wave with maximum transmitting range of 32 meters.

Summary Statistics of CPB-Qualified Public Radio Stations: Fiscal Year 1971.

ERIC Educational Resources Information Center

Lee, S. Young; Pedone, Ronald J.

Basic statistics on finance, employment, and broadcast and production activities of 103 Corporation for Public Broadcasting (CPB)--qualified radio stations in the United States and Puerto Rico for Fiscal Year 1971 are collected. The first section of the report deals with total funds, income, direct operating costs, capital expenditures, and other…

Developing hot air assisted radio frequency drying for in-shell Macadamia nuts

USDA-ARS?s Scientific Manuscript database

Dehydration offers a means of preserving foods in a stable and safe condition as it reduces water activity and extends shelf-life of perishable agricultural products. The purpose of this study was to develop radio frequency (RF) drying protocols for in-shell macadamia nuts based on conventional hot ...

77 FR 39797 - Pipeline Safety: Information Collection Activities

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-05

... (IC) to help determine the effectiveness of PHMSA's 811 Public Service Announcement (PSA) campaign. In...'' toll-free telephone number, PHMSA produced a 30-second video PSA, a 30-second radio PSA and a 60-second radio PSA. All were produced in both English and Spanish and are available in several formats for...

Sporadic radio emission connected with a definite manifestation of solar activity in the near Earth space

NASA Technical Reports Server (NTRS)

Dudnic, A. V.; Zaljubovski, I. I.; Kartashev, V. M.; Shmatko, E. S.

1985-01-01

Sporadic radio emission of near Earth space at the frequency of 38 MHz is shown to appear in the event of a rapid development of instabilities in the ionospheric plasma. The instabilities are generated due to primary ionospheric disturbances occurring under the influence of solar chromospheric flares.

A New Peak of Leonids observed by Radio Technics

NASA Astrophysics Data System (ADS)

Suzuki, K.; Maegawa, K.; Minagawa, Y.

Radio meteor observations with amateur ham radio wave have been carried out in Japan since August, 1996, by using forward-scattered meteor echoes of VHF radio waves (53.75MHz, 50W, CW) transmitted in Sabae, Fukui prefecture. A strong activity of Leonids was observed between 22h and 01h on November 16/17 (UT), 1996. The hourly rate of long duration echoes reached over 50 times larger than in non-shower period and 1.2 to 1.5 times larger than that at the normal maximum of Leonids, respectively. This enhanced activity occurred at a solar longitude (SL) of 234.95 plus or minus 0.05 degrees (2000.0 eq.), and is probably different from normal peak of Leonids at 235.45 plus or minus 0.05 degrees(2000.0 eq.) observed in 1990's. A corresponding peak in 1995 was also reported by visual meteor observation by many observers in Japan. The ascending node of Comet Tempel-Tuttle in 1966 was at 235.11 degrees in SL, and is closer to the new peak than the normal one (at 235.45 degrees in SL).

POWERFUL ACTIVITY IN THE BRIGHT AGES. I. A VISIBLE/IR SURVEY OF HIGH REDSHIFT 3C RADIO GALAXIES AND QUASARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hilbert, B.; Chiaberge, M.; Kotyla, J. P.

2016-07-01

We present new rest-frame UV and visible observations of 22 high- z (1 < z < 2.5) 3C radio galaxies and QSOs obtained with the Hubble Space Telescope ’s Wide Field Camera 3 instrument. Using a custom data reduction strategy in order to assure the removal of cosmic rays, persistence signal, and other data artifacts, we have produced high-quality science-ready images of the targets and their local environments. We observe targets with regions of UV emission suggestive of active star formation. In addition, several targets exhibit highly distorted host galaxy morphologies in the rest frame visible images. Photometric analyses revealmore » that brighter QSOs generally tend to be redder than their dimmer counterparts. Using emission line fluxes from the literature, we estimate that emission line contamination is relatively small in the rest frame UV images for the QSOs. Using archival VLA data, we have also created radio map overlays for each of our targets, allowing for analysis of the optical and radio axes alignment.« less

X-ray spectra and time variability of active galactic nuclei

NASA Technical Reports Server (NTRS)

Mushotzky, R. F.

1984-01-01

The X-ray spectra of broad line active galactic nuclei (AGN) of all types (Seyfert I's, NELG's, broadline radio galaxies) are well fit by a power law in the .5 to 100 keV band of man energy slope alpha = .68 + or - .15. There is, as yet, no strong evidence for time variability of this slope in a given object. The constraints that this places on simple models of the central energy source are discussed. BL Lac objects have quite different X-ray spectral properties and show pronounced X-ray spectral variability. On time scales longer than 12 hours most radio quiet AGN do not show strong, delta I/I .5, variability. The probability of variability of these AGN seems to be inversely related to their luminosity. However characteristics timescales for variability have not been measured for many objects. This general lack of variability may imply that most AGN are well below the Eddington limit. Radio bright AGN tend to be more variable than radio quiet AGN on long, tau approx 6 month, timescales.

Population density effect on radio frequencies interference (RFI) in radio astronomy

NASA Astrophysics Data System (ADS)

Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin; Hassan, Mohd Saiful Rizal; Rosli, Zulfazli; Hamidi, Zety Shahrizat

2012-06-01

Radio astronomical observation is infected by wide range of Radio Frequency Interference (RFI). We will also use information gathered from on-site RFI level measurements on selected 'good' areas generated by this study. After investigating a few suitable sites we will commence to the site and construct the RFI observation. Eventually, the best area we will be deciding from the observations soon. The result of this experiment will support our planning to build the first radio telescope in Malaysia. Radio observatories normally are located in remote area, in order to combat RFI from active spectrum users and radio noise produced in industrial or residential areas. The other solution for this problem is regulating the use of radio frequencies in the country (spectrum management). Measurement of RFI level on potential radio astronomical site can be done to measure the RFI levels at sites. Seven sites are chosen divide by three group, which is A, B and C. In this paper, we report the initial testing RFI survey for overall spectrum (0-2GHz) for those sites. The averaged RFI level above noise level at the three group sites are 19.0 (+/-1.79) dBm, 19.5 (+/-3.71) dBm and 17.0 (+/-3.71) dBm and the averaged RFI level above noise level for without main peaks are 20.1 (+/-1.77) dBm, 19.6 (+/-3.65) dBm and 17.2 (+/-1.43) dBm respectively.

A catalogue of faint local radio AGN and the properties of their host galaxies

NASA Astrophysics Data System (ADS)

Lofthouse, E. K.; Kaviraj, S.; Smith, D. JB; Hardcastle, M. J.

2018-05-01

We present a catalogue of local (z < 0.1) galaxies that contain faint AGN. We select these objects by identifying galaxies that exhibit a significant excess in their radio luminosities, compared to what is expected from the observed levels of star-formation activity in these systems. This is achieved by comparing the optical (spectroscopic) star formation rate (SFR) to the 1.4 GHz luminosity measured from the FIRST survey. The majority of the AGN identified in this study are fainter than those in previous work, such as in the Best and Heckman (2012) catalogue. We show that these faint AGN make a non-negligible contribution to the radio luminosity function at low luminosities (below 1022.5 W Hz-1), and host ˜13 per cent of the local radio luminosity budget. Their host galaxies are predominantly high stellar-mass systems (with a median stellar mass of 1011M⊙), are found across a range of environments (but typically in denser environments than star-forming galaxies) and have early-type morphologies. This study demonstrates a general technique to identify AGN in galaxy populations where reliable optical SFRs can be extracted using spectro-photometry and where radio data are also available so that a radio excess can be measured. Our results also demonstrate that it is unsafe to infer SFRs from radio emission alone, even if bright AGN have been excluded from a sample, since there is a significant population of faint radio AGN which may contaminate the radio-derived SFRs.

Space Telecommunications Radio Architecture (STRS)

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.

2006-01-01

A software defined radio (SDR) architecture used in space-based platforms proposes to standardize certain aspects of radio development such as interface definitions, functional control and execution, and application software and firmware development. NASA has charted a team to develop an open software defined radio hardware and software architecture to support NASA missions and determine the viability of an Agency-wide Standard. A draft concept of the proposed standard has been released and discussed among organizations in the SDR community. Appropriate leveraging of the JTRS SCA, OMG's SWRadio Architecture and other aspects are considered. A standard radio architecture offers potential value by employing common waveform software instantiation, operation, testing and software maintenance. While software defined radios offer greater flexibility, they also poses challenges to the radio development for the space environment in terms of size, mass and power consumption and available technology. An SDR architecture for space must recognize and address the constraints of space flight hardware, and systems along with flight heritage and culture. NASA is actively participating in the development of technology and standards related to software defined radios. As NASA considers a standard radio architecture for space communications, input and coordination from government agencies, the industry, academia, and standards bodies is key to a successful architecture. The unique aspects of space require thorough investigation of relevant terrestrial technologies properly adapted to space. The talk will describe NASA s current effort to investigate SDR applications to space missions and a brief overview of a candidate architecture under consideration for space based platforms.

Space Telecommunications Radio Architecture (STRS): Technical Overview

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.

2006-01-01

A software defined radio (SDR) architecture used in space-based platforms proposes to standardize certain aspects of radio development such as interface definitions, functional control and execution, and application software and firmware development. NASA has charted a team to develop an open software defined radio hardware and software architecture to support NASA missions and determine the viability of an Agency-wide Standard. A draft concept of the proposed standard has been released and discussed among organizations in the SDR community. Appropriate leveraging of the JTRS SCA, OMG s SWRadio Architecture and other aspects are considered. A standard radio architecture offers potential value by employing common waveform software instantiation, operation, testing and software maintenance. While software defined radios offer greater flexibility, they also poses challenges to the radio development for the space environment in terms of size, mass and power consumption and available technology. An SDR architecture for space must recognize and address the constraints of space flight hardware, and systems along with flight heritage and culture. NASA is actively participating in the development of technology and standards related to software defined radios. As NASA considers a standard radio architecture for space communications, input and coordination from government agencies, the industry, academia, and standards bodies is key to a successful architecture. The unique aspects of space require thorough investigation of relevant terrestrial technologies properly adapted to space. The talk will describe NASA's current effort to investigate SDR applications to space missions and a brief overview of a candidate architecture under consideration for space based platforms.

NASA's SDR Standard: Space Telecommunications Radio System

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.; Johnson, Sandra K.

2007-01-01

A software defined radio (SDR) architecture used in space-based platforms proposes to standardize certain aspects of radio development such as interface definitions, functional control and execution, and application software and firmware development. NASA has charted a team to develop an open software defined radio hardware and software architecture to support NASA missions and determine the viability of an Agency-wide Standard. A draft concept of the proposed standard has been released and discussed among organizations in the SDR community. Appropriate leveraging of the JTRS SCA, OMG s SWRadio Architecture and other aspects are considered. A standard radio architecture offers potential value by employing common waveform software instantiation, operation, testing and software maintenance. While software defined radios offer greater flexibility, they also poses challenges to the radio development for the space environment in terms of size, mass and power consumption and available technology. An SDR architecture for space must recognize and address the constraints of space flight hardware, and systems along with flight heritage and culture. NASA is actively participating in the development of technology and standards related to software defined radios. As NASA considers a standard radio architecture for space communications, input and coordination from government agencies, the industry, academia, and standards bodies is key to a successful architecture. The unique aspects of space require thorough investigation of relevant terrestrial technologies properly adapted to space. The talk will describe NASA s current effort to investigate SDR applications to space missions and a brief overview of a candidate architecture under consideration for space based platforms.

Gas kinematics in powerful radio galaxies at z 2: Energy supply from star formation, AGN, and radio jets⋆

NASA Astrophysics Data System (ADS)

Nesvadba, N. P. H.; Drouart, G.; De Breuck, C.; Best, P.; Seymour, N.; Vernet, J.

2017-04-01

We compare the kinetic energy and momentum injection rates from intense star formation, bolometric AGN radiation, and radio jets with the kinetic energy and momentum observed in the warm ionized gas in 24 powerful radio galaxies at z 2. These galaxies are among our best candidates for being massive galaxies near the end of their active formation period, when intense star formation, quasar activity, and powerful radio jets all co-exist. All galaxies have VLT/SINFONI imaging spectroscopy of the rest-frame optical line emission, showing extended emission-line regions with large velocity offsets (up to 1500 km s-1) and line widths (typically 800-1000 km s-1) consistent with very turbulent, often outflowing gas. As part of the HeRGÉ sample, they also have FIR estimates of the star formation and quasar activity obtained with Herschel/PACS and SPIRE, which enables us to measure the relative energy and momentum release from each of the three main sources of feedback in massive, star-forming AGN host galaxies during their most rapid formation phase. We find that star formation falls short by factors 10-1000 of providing the energy and momentum necessary to power the observed gas kinematics. The obscured quasars in the nuclei of these galaxies provide enough energy and momentum in about half of the sample, however, only if both are transferred to the gas relatively efficiently. We compare with theoretical and observational constraints on the efficiency of the energy and momentum transfer from jet and AGN radiation, which favors the radio jets as main drivers of the gas kinematics. Based on observations carried out with the Very Large Telescope of ESO under Program IDs 079.A-0617, 084.A-0324, 085.A-0897, and 090.A-0614.Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

The First VLBI Detection of a Spiral DRAGN Core

NASA Astrophysics Data System (ADS)

Mao, Minnie Y.; Blanchard, Jay M.; Owen, Frazer; Sjouwerman, Loránt O.; Singh, Vikram; Scaife, Anna; Paragi, Zsolt; Norris, Ray P.; Momjian, Emmanuel; Johnson, Gia; Browne, Ian

2018-05-01

We present the first observation of 0313-192, the archetypal spiral DRAGN, at VLBI resolutions. Spiral DRAGNs are Double Radio Sources Associated with Galactic Nuclei (DRAGNs) that are hosted by spiral galaxies. 0313-192 is an edge-on spiral galaxy that appears to host a 360 kpc double-lobed radio source. The core of this galaxy is clearly detected at L, S, and X-bands using the VLBA, signifying an ongoing active nucleus in the galaxy. This rules out the possibility that the spiral DRAGN is merely a chance alignment. The radio core has L1.4 GHz ˜ 3.0 × 1023 W Hz-1. Radio components are detected to the South-West of the core, but there are no detections of a counterjet. Assuming a symmetric, relativistic jet, we estimate an upper limit to the inclination angle of θ ≲ 72 degrees. The VLBI-detected radio jet components are extremely well-aligned with the larger-scale radio source suggested little to no jet disruption or interaction with the ISM of the host galaxy.

The first VLBI detection of a spiral DRAGN core

NASA Astrophysics Data System (ADS)

Mao, Minnie Y.; Blanchard, Jay M.; Owen, Frazer; Sjouwerman, Loránt O.; Singh, Vikram; Scaife, Anna; Paragi, Zsolt; Norris, Ray P.; Momjian, Emmanuel; Johnson, Gia; Browne, Ian

2018-07-01

We present the first observation of 0313-192, the archetypal spiral DRAGN, at very long baseline interferometry (VLBI) resolutions. Spiral DRAGNs are Double-lobed Radio sources Associated with Galactic Nuclei (DRAGNs) that are hosted by spiral galaxies. 0313-192 is an edge-on spiral galaxy that appears to host a 360 kpc double-lobed radio source. The core of this galaxy is clearly detected at L, S, and X bands using the Very Long Baseline Array, signifying an ongoing active nucleus in the galaxy. This rules out the possibility that the spiral DRAGN is merely a chance alignment. The radio core has L1.4 GHz ˜ 3.0 × 1023 W Hz-1. Radio components are detected to the south-west of the core, but there are no detections of a counterjet. Assuming a symmetric, relativistic jet, we estimate an upper limit to the inclination angle of θ ≲ 72 deg. The VLBI-detected radio jet components are extremely well aligned with the larger scale radio source suggesting little to no jet disruption or interaction with the interstellar medium of the host galaxy.

Properties of Radio Sources in the FRB 121102 Field

NASA Astrophysics Data System (ADS)

Bower, Geoffrey C.; Chatterjee, Shami; Wharton, Robert; Law, Casey J.; Hessels, Jason; Spolaor, Sarah; Abruzzo, Matthew W.; Bassa, Cees; Butler, Bryan J.; Cordes, James M.; Demorest, Paul; Kaspi, Victoria M.; McLaughlin, Maura; Ransom, Scott M.; Scholz, Paul; Seymour, Andrew; Spitler, Laura; Tendulkar, Shriharsh P.; PALFA Survey; VLA+AO FRB121102 Simultaneous Campaign Team; EVN FRB121102 Campaign Team; Realfast Team

2017-01-01

Fast radio bursts are millisecond duration radio pulses of unknown origin. With dispersion measures substantially in excess of expected Galactic contributions, FRBs are inferred to originate extragalactically, implying very high luminosities. Models include a wide range of high energy systems such as magnetars, merging neutron star binaries, black holes, and strong stellar magnetic fields driving coherent radio emission. Central to the mystery of FRB origins are the absence of confirmed host objects at any wavelength. This is primarily the result of the poor localization from single dish detection of FRBs. Of the approximately 20 known examples, only one, FRB 121102, has been observed to repeat. This repetition presents an opportunity for detailed follow-up if interferometric localization to arcsecond accuracy can be obtained. The Very Large Array has previously been used to localize individual pulses from pulsars and rotating radio transients to arcsecond localizaiton. We present here the results of radio observations of the field of FRB 121102 that permit us to constrain models of possible progenitors of this bursting source. These observations can characterize active galactic nuclei, stars, and other progenitor objects.

JVLA Observations of Young Brown Dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

We present sensitive 3.0 cm JVLA radio continuum observations of six regions of low-mass star formation that include twelve young brown dwarfs (BDs) and four young BD candidates. We detect a total of 49 compact radio sources in the fields observed, of which 24 have no reported counterparts and are considered new detections. Twelve of the radio sources show variability in timescales of weeks to months, suggesting gyrosynchrotron emission produced in active magnetospheres. Only one of the target BDs, FU Tau A, was detected. However, we detected radio emission associated with two of the BD candidates, WL 20S and CHLTmore » 2. The radio flux densities of the sources associated with these BD candidates are more than an order of magnitude larger than expected for a BD and suggest a revision of their classification. In contrast, FU Tau A falls on the well-known correlation between radio luminosity and bolometric luminosity, suggesting that the emission comes from a thermal jet and that this BD seems to be forming as a scaled-down version of low-mass stars.« less

SPA Meteor Section Results: 2006

NASA Astrophysics Data System (ADS)

McBeath, Alastair

2010-12-01

A summary of the main analyzed results and other information provided to the SPA Meteor Section from 2006 is presented and discussed. Events covered include: the radio Quadrantid maximum on January 3/4; an impressive fireball seen from parts of England, Belgium and the Netherlands at 22h53m51s UT on July 18, which was imaged from three EFN stations as well; the Southern delta-Aquarid and alpha-Capricornid activity from late July and early August; the radio Perseid maxima on August 12/13; confirmation that the October 5/6 video-meteor outburst was not observed by radio; visual and radio findings from the strong, bright-meteor, Orionid return in October; another impressive UK-observed fireball on November 1/2, with an oil painting of the event as seen from London; the Leonids, which produced a strong visual maximum around 04h-05h UT on November 18/19 that was recorded much less clearly by radio; radio and visual reports from the Geminids, with a note regarding NASA-observed Geminid lunar impact flashes; and the Ursid outburst recorded by various techniques on December 22.

SBS 0846+513: a new γ-ray-emitting narrow-line Seyfert 1 galaxy

DOE PAGES

D'Ammando, F.; Orienti, M.; Finke, J.; ...

2012-10-11

In this paper, we report Fermi Large Area Telescope (LAT) observations of the radio-loud active galactic nucleus SBS 0846+513 (z = 0.5835), optically classified as a narrow-line Seyfert 1 galaxy, together with new and archival radio-to-X-ray data. The source was not active at γ-ray energies during the first two years of Fermi operation. A significant increase in activity was observed during 2010 October–2011 August. In particular, a strong γ-ray flare was observed in 2011 June reaching an isotropic γ-ray luminosity (0.1–300 GeV) of 1.0 × 10 48 erg s -1, comparable to that of the brightest flat spectrum radio quasars,more » and showing spectral evolution in γ rays. An apparent superluminal velocity of (8.2 ± 1.5)c in the jet was inferred from 2011 to 2012 Very Long Baseline Array (VLBA) images, suggesting the presence of a highly relativistic jet. Finally, both the power released by this object during the flaring activity and the apparent superluminal velocity are strong indications of the presence of a relativistic jet as powerful as those of blazars. In addition, variability and spectral properties in radio and γ-ray bands indicate blazar-like behaviour, suggesting that, except for some distinct optical characteristics, SBS 0846+513 could be considered as a young blazar at the low end of the blazar's black hole mass distribution.« less

An infrared jet in Centaurus A - A link to the extranuclear activity in distant radio galaxies?

NASA Technical Reports Server (NTRS)

Joy, Marshall; Harvey, P. M.; Tollestrup, E. V.; Sellgren, K.; Mcgregor, P. J.

1991-01-01

High-resolution NIR images of the visually obscured central region of Centaurus A (NGC 5128) were obtained with the University of Texas array camera on the AAT in June 1988, in order to investigate the effect of the active nucleus on the surrounding galaxy. The J (1.25 micron), H (1.65 micron), and K (2.2 micron) images of the central 40 arcsec of the galaxy revealed an emission feature extending about 10 arcsec northeast of the nucleus at the same position angle as the X-ray and radio jets. This jet is most prominent at the 1.25 micron wavelength, where its brightness was comparable to that of the nucleus. The observed properties of the 'infrared jet' were found to be similar to those seen in distant radio sources.

Multiwavelength and Statistical Research in Space Astrophysics

NASA Technical Reports Server (NTRS)

Feigelson, Eric D.

1997-01-01

The accomplishments in the following three research areas are summarized: multiwavelength study of active galactic nuclei; magnetic activity of young stellar objects; and statistical methodology for astronomical data analysis. The research is largely based on observations of the ROSAT and ASCA X-ray observatories, complemented by ground-based optical and radio studies. Major findings include: discovery of inverse Compton X-ray emission from radio galaxy lobes; creation of the largest and least biased available sample of BL Lac objects; characterization of X-ray and nonthermal radio emission from T Tauri stars; obtaining an improved census of young stars in a star forming region and modeling the star formation history and kinematics; discovery of X-ray emission from protostars; development of linear regression methods and codes for interpreting astronomical data; and organization of the first cross-disciplinary conferences for astronomers and statisticians.

Nuclear Radio Jet from a Low-luminosity Active Galactic Nucleus in NGC 4258

NASA Astrophysics Data System (ADS)

Doi, Akihiro; Kohno, Kotaro; Nakanishi, Kouichiro; Kameno, Seiji; Inoue, Makoto; Hada, Kazuhiro; Sorai, Kazuo

2013-03-01

The nearby low-luminosity active galactic nucleus (LLAGN) NGC 4258 has a weak radio continuum component at the galactic center. We investigate its radio spectral properties on the basis of our new observations using the Nobeyama Millimeter Array at 100 GHz and archival data from the Very Large Array at 1.7-43 GHz and the James Clerk Maxwell telescope at 347 GHz. The NGC 4258 nuclear component exhibits (1) an intra-month variable and complicated spectral feature at 5-22 GHz and (2) a slightly inverted spectrum at 5-100 GHz (α ~ 0.3; F νvpropνα) in time-averaged flux densities, which are also apparent in the closest LLAGN M81. These similarities between NGC 4258 and M81 in radio spectral natures in addition to previously known core shift in their AU-scale jet structures produce evidence that the same mechanism drives their nuclei. We interpret the observed spectral property as the superposition of emission spectra originating at different locations with frequency-dependent opacity along the nuclear jet. Quantitative differences between NGC 4258 and M81 in terms of jet/counter jet ratio, radio loudness, and degree of core shift can be consistently understood by fairly relativistic speeds (Γ >~ 3) of jets and their quite different inclinations. The picture established from the two closest LLAGNs is useful for understanding the physical origin of unresolved and flat/inverted spectrum radio cores that are prevalently found in LLAGNs, including Sgr A*, with starved supermassive black holes in the present-day universe.

Up and Down the Black Hole Radio/X-Ray Correlation: The 2017 Mini-outbursts from Swift J1753.5-0127

NASA Astrophysics Data System (ADS)

Plotkin, R. M.; Bright, J.; Miller-Jones, J. C. A.; Shaw, A. W.; Tomsick, J. A.; Russell, T. D.; Zhang, G.-B.; Russell, D. M.; Fender, R. P.; Homan, J.; Atri, P.; Bernardini, F.; Gelfand, J. D.; Lewis, F.; Cantwell, T. M.; Carey, S. H.; Grainge, K. J. B.; Hickish, J.; Perrott, Y. C.; Razavi-Ghods, N.; Scaife, A. M. M.; Scott, P. F.; Titterington, D. J.

2017-10-01

The candidate black hole X-ray binary Swift J1753.5-0127 faded to quiescence in 2016 November after a prolonged outburst that was discovered in 2005. Nearly three months later, the system displayed renewed activity that lasted through 2017 July. Here, we present radio and X-ray monitoring over ≈ 3 months of the renewed activity to study the coupling between the jet and the inner regions of the disk/jet system. Our observations cover low X-ray luminosities that have not historically been well-sampled ({L}{{X}}≈ 2× {10}33{--}{10}36 {erg} {{{s}}}-1; 1-10 keV), including time periods when the system was both brightening and fading. At these low luminosities, Swift J1753.5-0127 occupies a parameter space in the radio/X-ray luminosity plane that is comparable to “canonical” systems (e.g., GX 339-4), regardless of whether the system was brightening or fading, even though during its ≳11 year outburst, Swift J1753.5-0127 emitted less radio emission from its jet than expected. We discuss implications for the existence of a single radio/X-ray luminosity correlation for black hole X-ray binaries at the lowest luminosities ({L}{{X}}≲ {10}35 {erg} {{{s}}}-1), and we compare to supermassive black holes. Our campaign includes the lowest luminosity quasi-simultaneous radio/X-ray detection to date for a black hole X-ray binary during its rise out of quiescence, thanks to early notification from optical monitoring combined with fast responses from sensitive multiwavelength facilities.

The two-stage origin of bright rings in extended radio lobes

NASA Astrophysics Data System (ADS)

Morrison, P.; Sadun, A.

1996-01-01

A few strong radio sources show unusual large-intensity features (up to 100- or 200-kpc scale) within their extended lobes. These appear in the plane of the sky as nearly circular rings, but physically they are actually spherical shells. Two such sources, HerA (3C348) and 3C310, are analysed in terms of their similarly uniform kinematics. Such objects do not easily fit into the Fanaroff-Riley scheme for jet and lobe sources. We model these sources by a two-stage account of their dynamics. Long ago, acoustic waves (or weak shocks) were excited again and again to form sphere after sphere in the pre-existing thermal galactic wind. They all arose at one spot along the jet axis at the edge of the galaxy, to drift with the wind, expanding uniformly at the speed of sound in the near-isothermal gas. The wind flows out supersonically at about Mach 5. In a much later second stage, a new and much faster flow of relativistic plasma is energized by the active nucleus deep within the galaxy. That plasma jet swiftly forms the radio lobe and infuses it with radio electrons. The new plasma fills in locally the low-pressure portions of each drifting acoustic shell. The shells then appear as a procession of radio rings, with modest intensity contrast and an understandable polarization. Both of these radio ring sources appear to have optically double active nuclei. Perhaps periodic tidal forces determine the density modulations during the older outflow that gave rise to the several drifting shells.

Review of Space VLBI RadioAstron studies of AGN

NASA Astrophysics Data System (ADS)

Gurvits, Leonid; Kovalev, Yuri

2016-07-01

Space VLBI offers an unrivalled resolution in studies of the AGN phenomena. Since 2011, the Russia-led SVLBI mission RadioAstron conducts observations at 92, 18, 6 and 1.3 cm with baselines an order of magnitude longer than the Earth diameter, therefore offering an order of magnitude "sharper" view at the brightest radio sources than achieved with Earth-based VLBI systems. In our presentation we will review the current status of the RadioAstron's scientific programme. Over the first 4.5 years of the in-orbit operations, the mission achieved successful VLBI detections of extragalactic continuum radio sources at all four observing bands. To date, detections on SVLBI baselines have been obtained for more than 150 AGN's at projected baselines up to 350 000 km (about 28 Earth diameters, ED). The highest resolution achieved is 14 microarcscends from 1.3 cm observations. RadioAstron is an international project; it conducts observations with up to 30 Earth-based radio telescopes located on different continents. We will review results of total intensity and polarisation imaging with extreme angular resolution of blazars and nearby active galaxies. We will also discuss typical and maximum brightness temperatures of blazar cores from the AGN Survey obtained with RadioAstron. Physical implications for the AGN jets formation, magnetic field and emission mechanism will be discussed on the basis of the results obtained to date.

An MF/HF radio array for radio and radar imaging of the ionosphere

NASA Astrophysics Data System (ADS)

Isham, Brett; Gustavsson, Bjorn; Belyey, Vasyl; Bullett, Terrence

2016-07-01

The Aguadilla Radio Array will be installed at the Interamerican University Aguadilla Campus, located in northwestern Puerto Rico. The array is intended for broad-band medium and high-frequency (MF/HF, roughly 2 to 25 MHz) radio and bistatic radar observations of the ionosphere. The main array consists of 20 antenna elements, arranged in a semi-random pattern providing a good distribution of baseline vectors, with 6-meter minimum spacing to eliminate spacial aliasing. A relocatable 6-element array is also being developed, in which each element consists of a crossed pair of active electric dipoles and all associated electronics for phase-coherent radio measurements. A primary scientific goal of the array is to create images of the region of ionospheric radio emissions stimulated by the new Arecibo Observatory high-power high-frequency radio transmitter. A second primary goal is the study of ionospheric structure and dynamics via coherent radar imaging of the ionosphere in collaboration with the University of Colorado / NOAA Versatile Interferometric Pulsed Ionospheric Radar (VIPIR), located at the USGS San Juan Observatory in Cayey, Puerto Rico. In addition to ionospheric research in collaboration with the Cayey and Arecibo Observatories, the goals of the project include the development of radio sounding, polarization, interferometry, and imaging techniques, and training of students at the university and high school levels.

Obituary: Daniel E. Harris (1934 - 2015)

NASA Astrophysics Data System (ADS)

Madrid, Juan P.; Massaro, Francesco; Cheung, Teddy

Our friend and colleague, Daniel E. Harris, died on December 6th 2015. Dan was a passionate astronomer and world traveller. He led a rich and scientifically productive life until the end. Dan was the first person to receive a PhD in radio astronomy at Caltech where he was a student of John Bolton, one of the fathers of Radio Astronomy and the founder of the Owens Valley Radio Observatory that Dan used for his thesis and first publications. One of Dan's first projects was with Jim Roberts to measure improved positions and flux densities for radio sources in the newly released 3C catalog. During this study, Dan discovered the first flat spectrum radio sources, which he named CTA 21, CTA 26, and CTA 102 and which were later identified as quasars. His PhD thesis resulted in the then definitive study of the evolution of supernova remnants. Later Dan worked on radio galaxies and active galactic nuclei (AGN) first at radio and then at X-ray wavelengths with the Einstein, ROSAT, and Chandra Observatories where he pioneered the new field of relativistic X-ray jets and how they relate to radio galaxies and AGN. After graduating from Caltech in 1961, Dan wanted to see the world. Beginning in 1962, Dan lived in Bologna, Italy, where he worked with Professor Marcello Ceccarelli and the radio astronomy group and was active in the construction of the Northern Cross Radio Observatory ("la Croce"), the first Italian radio telescope. He left Bologna in the Spring of 1964 as his friends remember him to "divenir del mondo esperto e de li vizi umani e del valore"1, as he joined V. Radhakrishnan (Rad) and Dave Morris to sail in a 36-ft trimaran from England to Puerto Rico where he took a position at the Arecibo Observatory working with Marshall Cohen on interplanetary scintillations. After five years at the Arecibo Observatory, Dan went on to work at the Argentinian Institute of Radio Astronomy, Harvard University, the Dwingeloo Radio Observatory in the Netherlands, and at the Dominion Radio Observatory in Penticton, Canada. He finally returned to the U.S. in 1980 and spent the next 35 years at the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Massachusetts. One of Dan's most memorable attributes was his cheerful enjoyment of life. Dan was the life of the party; he was joyful, open and friendly. Dan enjoyed good food, drinks, and conversations with friends and strangers alike. Dan belonged to a time prior to big egos when scientific discoveries seemed to be made by the curious, adventurous, and non-conformists. Dan's free spirit manifested itself in his publications. Dan was a rigorous scientist who was not afraid of writing his papers with a hint of good humour. When presenting new radio measurements Dan went for "descriptive names" to describe radio maps2 such as the "original," the "goldfish," the "double," the "beaver," the "bean." At a recent IAU symposium held in the Galápagos Islands, where many of his colleagues and friends gathered to celebrate his 80th birthday, Dan's talk was entitled: "Slugs and Snails and Puppy Dog Tails: jets from an unconventional angle." As Dan worked with observatories outside the university system he was not officially a faculty member, but he mentored and collaborated with many younger researchers. This younger crowd that with sadness write these lines, always looked up to Dan as a role model in life as well as science, and will most of all miss his steadfast support. He was always ready to share his experience, expertise, and data. Even after leaving his full-time position with Chandra, Dan never retired. He kept working part-time at the SAO where he continued his research and was awarded competitive grants, telescope time, published, and led collaborations. Dan also worked for peace causes throughout his life. Dan joined the tax resistance movement during the Vietnam war, a movement of hundreds of thousands of Americans who refused to pay a portion of their income tax to the government in order to defund the war. He was also an active member of the organization that published the Astronomers and the Arms Race Newsletter. As a concerned scientist, Dan advocated against the star wars agenda and the militarization of space during the eighties. Dan was an active member of the AAS and frequent participant at meetings. The last meeting he attended was the 2015 Seattle one where he presented a talk and chaired a session. His presence at the 2015 meeting is a testament of his unwavering energy. Dan is survived by his wife Barbara, three children: Justine, Seth, and Leila, and four grandchildren.

Project Radio JOVE: Hands-On Radio Astronomy for the Classroom

NASA Astrophysics Data System (ADS)

Thieman, J. R.; Higgins, C. A.

2000-10-01

Radio Jove is a relatively new educational project to involve secondary school students in collecting and analyzing observations of the natural radio emissions of the planet Jupiter and the Sun. Participating students get hands-on experience in gathering and working with space science data. They obtain the data by either building a radio receiver and antenna and making observations with their equipment, or by remotely using professional radio telescopes through the web. They can then compare their results with other schools who had also observed and come to conclusions concerning the nature of the radio sources and how the radio waves propagate to Earth. Thus, they fully follow the method of scientific inquiry used by radio astronomers to study our solar system. (National Science Content Standard A: Science as Inquiry) More than 200 kits have been distributed thus far to schools and individuals as a result of the project. With the coming Cassini flyby of Jupiter we will be advocating a campaign in which many of the schools involved in the project will be observing at times of scientific interest. While Galileo and Cassini are monitoring Jovian radio emissions at lower frequencies, the schools will be observing at frequencies of 20.1 MHz (kit-based observations) or the frequencies available through the professional radio telescopes connected on-line. The aim will be to get a thorough picture of the levels of activity at Jupiter during the flyby period and how the radio signals are received at different observing stations around the world. An archive of observations submitted by the schools will be maintained at Goddard Space Flight Center and there will also be an archive of the professional telescopes data at the University of Florida. We hope that many students will have the feeling of being a part of the planetary exploration program as a result.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1984-01-01

Activities in space communication, radio navigation, radio science, and ground-based astronomy are reported. Advanced systems for the Deep Space Network and its Ground-Communications Facility are discussed including station control and system technology. Network sustaining as well as data and information systems are covered. Studies of geodynamics, investigations of the microwave spectrum, and the search for extraterrestrial intelligence are reported.

Radio Non-Detection of the Currently Outbursting Transient Source in NGC 6440

NASA Astrophysics Data System (ADS)

Tetarenko, A. J.; Bahramian, A.; Sivakoff, G. R.; Heinke, C. O.; Shaw, A. W.; Wijnands, R.; Degenaar, N.; Miller-Jones, J. C. A.; Kuulkers, R. Plotkin E.; Chomiuk, L.; Strader, J.; Tremou, E.; Kennea, J. A.; Altamirano, D.; in't Zand, J. J. M.; Deller, A.; Maccarone, T. J.

2017-10-01

We report follow-up VLA radio observations of NGC 6440, which has recently shown evidence of transient X-ray activity (ATel #10821, #10826). Our VLA observations occurred on 2017 Oct 11, with scans on source between 01:07:09 - 02:48:18 UTC (MJD = 58037.0466 - 58037.1169), in X band (8 - 12 GHz).

Solar-geophysical data number 496, December 1985. Part 1: (Prompt reports). Data for November 1985, October 1985 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E. (Editor)

1985-01-01

Data for November 1985 on IUWDS alert period; solar activity indices, solar flares, solar radio emission, VOSTOK inferred interplanetary magnetic field polarity, Stanford mean solar magnetic field, sudden ionospheric disturbances, cosmic ray measurements, geomagnetic indices, solar radio spectral observations, and calcium plage are presented.

The Diffusion and Impact of Radio Frequency Identification in Supply Chains: A Multi-Method Approach

ERIC Educational Resources Information Center

Wu, Xiaoran

2012-01-01

As a promising and emerging technology for supply chain management, Radio Frequency Identification (RFID) is a new alternative to existing tracking technologies and also allows a range of internal control and supply chain coordination. RFID has generated a significant amount of interest and activities from both practitioners and researchers in…

The γ-ray emission region in the Fanaroff-Riley II radio galaxy 3C 111

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grandi, P.; Torresi, E.; Stanghellini, C.

The broad-line radio galaxy 3C 111, characterized by a Fanaroff-Riley II (FRII) radio morphology, is one of the sources of the misaligned active galactic nucleus sample, consisting of radio galaxies and steep spectrum radio quasars, recently detected by the Fermi Large Area Telescope (LAT). In this analysis of the 24 month γ-ray light curve shows that 3C 111 was only occasionally detected at high energies. It was bright at the end of 2008 and faint, below the Fermi-LAT sensitivity threshold, for the rest of the time. A multifrequency campaign of 3C 111, ongoing in the same period, revealed an increasemore » of the millimeter, optical, and X-ray fluxes in 2008 September-November, interpreted by Chatterjee et al. as due to the passage of a superluminal knot through the jet core. Furthermore, the temporal coincidence of the millimeter-optical-X-ray outburst with the GeV activity suggests a cospatiality of the events, allowing, for the first time, the localization of the γ-ray dissipative zone in an FRII jet. Here, we argue that the GeV photons of 3C 111 are produced in a compact region confined within 0.1 pc and at a distance of about 0.3 pc from the black hole.« less

The γ-ray emission region in the Fanaroff-Riley II radio galaxy 3C 111

DOE PAGES

Grandi, P.; Torresi, E.; Stanghellini, C.

2012-04-30

The broad-line radio galaxy 3C 111, characterized by a Fanaroff-Riley II (FRII) radio morphology, is one of the sources of the misaligned active galactic nucleus sample, consisting of radio galaxies and steep spectrum radio quasars, recently detected by the Fermi Large Area Telescope (LAT). In this analysis of the 24 month γ-ray light curve shows that 3C 111 was only occasionally detected at high energies. It was bright at the end of 2008 and faint, below the Fermi-LAT sensitivity threshold, for the rest of the time. A multifrequency campaign of 3C 111, ongoing in the same period, revealed an increasemore » of the millimeter, optical, and X-ray fluxes in 2008 September-November, interpreted by Chatterjee et al. as due to the passage of a superluminal knot through the jet core. Furthermore, the temporal coincidence of the millimeter-optical-X-ray outburst with the GeV activity suggests a cospatiality of the events, allowing, for the first time, the localization of the γ-ray dissipative zone in an FRII jet. Here, we argue that the GeV photons of 3C 111 are produced in a compact region confined within 0.1 pc and at a distance of about 0.3 pc from the black hole.« less

High Resolution Rapid Response Observations of Compact Radio Sources with the Ceduna Hobart Interferometer (CHI)

NASA Technical Reports Server (NTRS)

Blanchard, Jay M.; Lovell, James E. J.; Ojha, Roopesh; Kadler, Matthias; Dickey, John M.; Edwards, Philip G.

2011-01-01

Context. Frequent, simultaneous observations across the electromagnetic spectrum are essential to the study of a range of astrophysical phenomena including Active Galactic Nuclei. A key tool of such studies is the ability to observe an object when it flares i.e. exhibits a rapid and significant increase in its flux density. Aims. We describe the specific observational procedures and the calibration techniques that have been developed and tested to create a single baseline radio interferometer. that can rapidly observe a flaring object. This is the only facility that is dedicated to rapid high resolution radio observations of an object south of -30 degrees declination. An immediate application is to provide rapid contemporaneous radio coverage of AGN flaring at y-ray frequencies detected by the Fermi Gamma-ray Space Telescope. Methods. A single baseline interferometer was formed with radio telescopes in Hobart, Tasmania and Ceduna, South Australia. A software correlator was set up at the University of Tasmania to correlate these data. Results. Measurements of the flux densities of flaring objects can be made using our observing strategy within half an hour of a triggering event. These observations can be calibrated with amplitude errors better than 20%. Lower limits to the brightness temperatures of the sources can also be calculated using CHI. Key words. instrumentation:interferometers - galaxies:active - galaxies:jets - galaxies:nuclei quasars:general gamma rays:galaxies- 1.

Peering through Jupiter’s clouds with radio spectral imaging

NASA Astrophysics Data System (ADS)

de Pater, Imke; Sault, R. J.; Butler, Bryan; DeBoer, David; Wong, Michael H.

2016-06-01

Radio wavelengths can probe altitudes in Jupiter’s atmosphere below its visible cloud layers. We used the Very Large Array to map this unexplored region down to ~8 bar, ~100 kilometers below the visible clouds. Our maps reveal a dynamically active planet at pressures less than 2 to 3 bar. A radio-hot belt exists, consisting of relatively transparent regions (a low ammonia concentration, NH3 being the dominant source of opacity) probing depths to over ~8 bar; these regions probably coincide with 5-micrometer hot spots. Just to the south we distinguish an equatorial wave, bringing up ammonia gas from Jupiter’s deep atmosphere. This wave has been theorized to produce the 5-micrometer hot spots; we observed the predicted radio counterpart of such hot spots.

Disaster Radio for Communication of Vital Messages and Health-Related Information: Experiences From the Haiyan Typhoon, the Philippines.

PubMed

Hugelius, Karin; Gifford, Mervyn; Örtenwall, Per; Adolfsson, Annsofie

2016-08-01

Crisis communication is seen as an integrated and essential part of disaster management measures. After Typhoon Haiyan (Yolanda) in the Philippines 2013, radio was used to broadcast information to the affected community. The aim of this study was to describe how disaster radio was used to communicate vital messages and health-related information to the public in one affected region after Typhoon Haiyan. Mixed-methods analysis using qualitative content analysis and descriptive statistics was used to analyze 2587 logged radio log files. Radio was used to give general information and to demonstrate the capability of officials to manage the situation, to encourage, to promote recovery and foster a sense of hope, and to give practical advice and encourage self-activity. The content and focus of the messages changed over time. Encouraging messages were the most frequently broadcast messages. Health-related messages were a minor part of all information broadcast and gaps in the broadcast over time were found. Disaster radio can serve as a transmitter of vital messages including health-related information and psychological support in disaster areas. The present study indicated the potential for increased use. The perception, impact, and use of disaster radio need to be further evaluated. (Disaster Med Public Health Preparedness. 2016;10:591-597).

A hot X-ray filament associated with A3017 galaxy cluster

NASA Astrophysics Data System (ADS)

Parekh, V.; Durret, F.; Padmanabh, P.; Pandge, M. B.

2017-09-01

Recent simulations and observations have shown large-scale filaments in the cosmic web connecting nodes, with accreting materials (baryonic and dark matter) flowing through them. Current high-sensitivity observations also show that the propagation of shocks through filaments can heat them up and make filaments visible between two or more galaxy clusters or around massive clusters, based on optical and/or X-ray observations. We are reporting here the special case of the cluster A3017 associated with a hot filament. The temperature of the filament is 3.4^{-0.77}_{+1.30} keV and its length is ∼1 Mpc. We have analysed its archival Chandra data and report various properties. We also analysed GMRT 235/610 MHz radio data. Radio observations have revealed symmetric two-sided lobes that fill cavities in the A3017 cluster core region, associated with central active galactic nucleus. In the radio map, we also noticed a peculiar linear vertical radio structure in the X-ray filament region which might be associated with a cosmic filament shock. This radio structure could be a radio phoenix or old plasma where an old relativistic population is re-accelerated by shock propagation. Finally, we put an upper limit on the radio luminosity of the filament region.

Radio emission in Mercury magnetosphere

NASA Astrophysics Data System (ADS)

Varela, J.; Reville, V.; Brun, A. S.; Pantellini, F.; Zarka, P.

2016-10-01

Context. Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field (IMF) on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the magnetohydrodynamic code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the IMF orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka et al. (2001, Astrophys. Space Sci., 277, 293), Zarka (2007, Planet. Space Sci., 55, 598) to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydrodynamic parameters of the solar wind, IMF orientations and intensities, that allow us to calculate the dissipated power distribution and infer the existence of radio emission hot spots on the planet day side, and to calculate the integrated radio emission of the Hermean magnetosphere. Results: The obtained radio emission distribution of dissipated power is determined by the IMF orientation (associated with the reconnection regions in the magnetosphere), although the radio emission strength is dependent on the IMF intensity and solar wind hydro parameters. The calculated total radio emission level is in agreement with the one estimated in Zarka et al. (2001, Astrophys. Space Sci., 277, 293) , between 5 × 105 and 2 × 106 W.

A combined radio and GeV γ-ray view of the 2012 and 2013 flares of Mrk 421

DOE PAGES

Hovatta, Talvikki; Petropoulou, M.; Richards, J. L.; ...

2015-03-09

In 2012 Markarian 421 underwent the largest flare ever observed in this blazar at radio frequencies. In the present study, we start exploring this unique event and compare it to a less extreme event in 2013. We use 15 GHz radio data obtained with the Owens Valley Radio Observatory 40-m telescope, 95 GHz millimetre data from the Combined Array for Research in Millimeter-Wave Astronomy, and GeV γ-ray data from the Fermi Gamma-ray Space Telescope. Here, the radio light curves during the flaring periods in 2012 and 2013 have very different appearances, in both shape and peak flux density. Assuming thatmore » the radio and γ-ray flares are physically connected, we attempt to model the most prominent sub-flares of the 2012 and 2013 activity periods by using the simplest possible theoretical framework. We first fit a one-zone synchrotron self-Compton (SSC) model to the less extreme 2013 flare and estimate parameters describing the emission region. We then model the major γ-ray and radio flares of 2012 using the same framework. The 2012 γ-ray flare shows two distinct spikes of similar amplitude, so we examine scenarios associating the radio flare with each spike in turn. In the first scenario, we cannot explain the sharp radio flare with a simple SSC model, but we can accommodate this by adding plausible time variations to the Doppler beaming factor. In the second scenario, a varying Doppler factor is not needed, but the SSC model parameters require fine-tuning. Both alternatives indicate that the sharp radio flare, if physically connected to the preceding γ-ray flares, can be reproduced only for a very specific choice of parameters.« less

INTERSTELLAR SCINTILLATION AND THE RADIO COUNTERPART OF THE FAST RADIO BURST FRB 150418

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akiyama, Kazunori; Johnson, Michael D., E-mail: kazu@haystack.mit.edu

Keane et al. have recently reported the discovery of a new fast radio burst (FRB), FRB 150418, with a promising radio counterpart at 5.5 and 7.5 GHz—a rapidly decaying source, falling from 200–300 μ Jy to 100 μ Jy on timescales of ∼6 days. This transient source may be associated with an elliptical galaxy at redshift z = 0.492, providing the first firm spectroscopic redshift for an FRB and the ability to estimate the density of baryons in the intergalactic medium via the combination of known redshift and radio dispersion of the FRB. An alternative explanation, first suggested by Williamsmore » and Berger, is that the identified counterpart may instead be a compact active galactic nucleus (AGN). The putative counterpart’s variation may then instead be extrinsic, caused by refractive scintillation in the ionized interstellar medium of the Milky Way, which would invalidate the association with FRB 150418. We examine this latter explanation in detail and show that the reported observations are consistent with scintillating radio emission from the core of a radio-loud AGN having a brightness temperature T {sub b} ≳ 10{sup 9} K. Using numerical simulations of the expected scattering for the line of sight to FRB 150418, we provide example images and light curves of such an AGN at 5.5 and 7.5 GHz. These results can be compared with continued radio monitoring to conclusively determine the importance of scintillation for the observed radio variability, and they show that scintillation is a critical consideration for continued searches for FRB counterparts at radio wavelengths.« less

Fermi LAT detection of renewed gamma-ray flaring activity from the radio galaxy NGC 1275 (Perseus A)

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2013-01-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed GeV gamma-ray flaring activity from a source positionally consistent with NGC 1275 (also known as 2FGL J0319.8+4130, Nolan et al. 2012, ApJS, 199, 31, as Perseus A and 3C 84) a radio galaxy located at the center of the Perseus galaxy cluster (see also Abdo et al. 2009, ApJ, 699, 31).

Solar-Geophysical Data Number 497, January 1986. Part 1: (Prompt reports). Date for December 1985, November 1985 and late data

NASA Technical Reports Server (NTRS)

Coffey, H. E.

1986-01-01

Solar-Geophysical Data Number 497, January 1986, Part 1 (prompt reports); Data for December 1985, November 1985 and Late Data contains the Data for December 1985-(IUWDS alert periods (advance and worldwide), solar activity indices, Solar flares, Vostok inferred interplanetary magnetic field polarity, Stanford mean solar magnetic field); data for November 1985-(solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements by neutron monitor, geomagnetic indices, radio propagation indices); and late data-(geomagnetic indices, calcium plage data).

Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norin, L.; Leyser, T. B.; Nordblad, E.

2009-02-13

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

PubMed

Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

2009-02-13

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

A Strong Radio Brightening at the Jet Base of M 87 during the Elevated Very High Energy Gamma-Ray State in 2012

NASA Astrophysics Data System (ADS)

Hada, K.; Giroletti, M.; Kino, M.; Giovannini, G.; D'Ammando, F.; Cheung, C. C.; Beilicke, M.; Nagai, H.; Doi, A.; Akiyama, K.; Honma, M.; Niinuma, K.; Casadio, C.; Orienti, M.; Krawczynski, H.; Gómez, J. L.; Sawada-Satoh, S.; Koyama, S.; Cesarini, A.; Nakahara, S.; Gurwell, M. A.

2014-06-01

We report our intensive, high angular resolution radio monitoring observations of the jet in M 87 with the VLBI Exploration of Radio Astrometry (VERA) and the European VLBI Network (EVN) from 2011 February to 2012 October, together with contemporaneous high-energy (100 MeV 100 GeV) γ rays by VERITAS. We detected a remarkable (up to ~70%) increase of the radio flux density from the unresolved jet base (radio core) with VERA at 22 and 43 GHz coincident with the VHE activity. Meanwhile, we confirmed with EVN at 5 GHz that the peculiar knot, HST-1, which is an alternative favored γ-ray production site located at gsim120 pc from the nucleus, remained quiescent in terms of its flux density and structure. These results in the radio bands strongly suggest that the VHE γ-ray activity in 2012 originates in the jet base within 0.03 pc or 56 Schwarzschild radii (the VERA spatial resolution of 0.4 mas at 43 GHz) from the central supermassive black hole. We further conducted VERA astrometry for the M 87 core at six epochs during the flaring period, and detected core shifts between 22 and 43 GHz, a mean value of which is similar to that measured in the previous astrometric measurements. We also discovered a clear frequency-dependent evolution of the radio core flare at 43, 22, and 5 GHz the radio flux density increased more rapidly at higher frequencies with a larger amplitude, and the light curves clearly showed a time-lag between the peaks at 22 and 43 GHz, the value of which is constrained to be within ~35-124 days. This indicates that a new radio-emitting component was created near the black hole in the period of the VHE event, and then propagated outward with progressively decreasing synchrotron opacity. By combining the obtained core shift and time-lag, we estimated an apparent speed of the newborn component propagating through the opaque region between the cores at 22 and 43 GHz. We derived a sub-luminal speed (less than ~0.2c) for this component. This value is significantly slower than the super-luminal (~1.1c) features that appeared from the core during the prominent VHE flaring event in 2008, suggesting that stronger VHE activity can be associated with the production of a higher Lorentz factor jet in M 87.

A Strong Radio Brightening At The Jet Base Of M 87 During The Elevated Very High Energy Gamma-Ray State In 2012

DOE PAGES

Hada, K.; Giroletti, M.; Kino, M.; ...

2014-06-04

We report our intensive, high-angular-resolution radio monitoring observations of the jet in M 87 with the VLBI Exploration of Radio Astrometry (VERA) and the European VLBI Network (EVN) from February 2011 to October 2012, together with contemporaneous high-energy (HE; 100 MeV< E <100 GeV) -ray light curves obtained by the Fermi Large Area Telescope (LAT). During this period (specifically from February 2012 to March 2012), an elevated level of the M 87 flux is reported at very-high-energy (VHE; E > 100 GeV) -rays by VERITAS. We detected a remarkable (up to ~70%) increase of the radio flux density from themore » unresolved jet base (radio core) with VERA at 22 and 43 GHz coincident with the VHE activity. Meanwhile, we confirmed with EVN at 5 GHz that the peculiar knot HST-1, which is an alternative favored -ray production site located at &120 pc from the nucleus, remained quiescent in terms of its flux density and structure. These results in the radio bands strongly suggest that the VHE -ray activity in 2012 originates in the jet base within 0.03 pc or 56 Schwarzschild radii (the VERA spatial resolution of 0.4 mas at 43 GHz) from the central supermassive black hole. We further conducted VERA astrometry for the M 87 core at six epochs during the flaring period, and detected core shifts between 22 and 43 GHz, a mean value of which is similar to that measured in the previous astrometric measurements. We also discovered a clear frequency-dependent evolution of the radio core flare at 43, 22 and 5 GHz; the radio flux density increased more rapidly at higher frequencies with a larger amplitude, and the light curves clearly showed a time-lag between the peaks at 22 and 43 GHz, the value of which is constrained to be within ~ 35 - 124 days. This indicates that a new radio-emitting component was created near the black hole in the period of the VHE event, and then propagated outward with progressively decreasing synchrotron opacity. By combining the obtained core shift and time-lag, we estimated an apparent speed of the newborn component propagating through the opaque region between the cores at 22 and 43 GHz. We derived a sub-luminal speed (less than ~0.2c) for this component. This value is significantly slower than the super-luminal (~1.1c) features that appeared from the core during the prominent VHE flaring event in 2008, suggesting that the stronger VHE activity can be associated with the production of the higher Lorentz factor jet in M 87.« less

Tracing Evolution of Starbursts and AGNs using Ultra-deep Radio and mm/smm Surveys

NASA Astrophysics Data System (ADS)

Yun, Min S.; Gim, Hansung; Morrison, Glenn; Hales, Christopher A.; Momjian, Emmanuel; Owen, Frazer; Kellermann, Ken; Aretxaga, Itziar; Giavalisco, Mauro; Hughes, David; Lowenthal, James; Miller, Neal; Kawabe, Ryohei; Kohno, Kotaro

2015-08-01

There is growing evidence supporting a rapid build up of metals among massive galaxies during their rapid growth via an intense starburst in the early epochs. These star formation activities may be largely obscured in the UV and optical light, as in the local universe. If the growth of supermassive blackholes occurs at or nearly the same time, the accompanying AGN activity may also be heavily obscured. Ultra-deep surveys in the radio and far-infrared can offer extinction-free view of these systems, and the advent of new facilities such as the Jansky VLA, ALMA, and LMT now allows us to probe directly the population of starburst galaxies that are responsible for the bulk of the stellar mass build-up during the epoch of galaxy growth (SFR > 10-100 M⊙/yr at z≈2 or earlier). We will present our analysis of the properties of the micro-Jansky radio sources identified by new Jansky VLA surveys of the GOODS and COSMOS fields using the rich archival data already available (Herschel, Spitzer, Chandra, ALMA, LMT, etc.). Specifically, we find evidence for two populations of microJy radio sources with distinct spectral index distribution. We explore whether this reflects differences in the underlying powering mechanisms by examining their radio-FIR correlation and X-ray properties. We also find the previously reported apparent systematic change in the "q-value" with increasing redshift, and we examine the reality of this trend in some detail. Finally, we will also examine the spatial extent of activities for a subset of the sample where high angular resolution (better than 1") information is available.

The Possible Submillimeter Bump and Accretion-jet in the Central Supermassive Black Hole of NGC 4993

NASA Astrophysics Data System (ADS)

Wu, Qingwen; Feng, Jianchao; Fan, Xuliang

2018-03-01

NGC 4993, as a host galaxy of the electromagnetic counterpart of the first gravitational-wave detection of a binary neutron-star merger, was observed by many powerful telescopes from radio to γ-ray wavebands. The weak nuclear activities of NGC 4993 suggest that it is a low-luminosity active galactic nuclei (LLAGNs). We build the multiwaveband spectral energy distributions (SEDs) of NGC 4993 from the literature. We find that the radio spectrum at ∼100–300 GHz is much steeper than that of the low-frequency waveband (e.g., 6–100 GHz), where this break was also found in the supermassive black holes (SMBHs) in our galaxy center (Sgr A*), and in some other nearby AGNs. The radio emission above and below this break may have different physical origins, which provide an opportunity to probe the accretion and jet properties. We model the multiwaveband SEDs of NGC 4993 with an advection-dominated accretion flow (ADAF) jet model. We find that the high-frequency steep radio emission at the millimeter waveband is consistent with the prediction of the ADAF, while the low-frequency flat radio spectrum is better fitted by the jet. Furthermore, the X-ray emission can also be simultaneously explained by the ADAF model. From the model fits, we estimate important parameters of the central engine (e.g., the accretion rate near the horizon of the black hole and the mass-loss rate in the jet) for NGC 4993. This result strengthens the theory that the millimeter, submillimeter, and deep X-ray observations are crucial to understanding the weak or quiescent activities in SMBH systems. Further simultaneous millimeter and X-ray monitoring of this kind of LLAGN will help us to better understand the physical origin of multiwaveband emission.

A State Change In The Missing Link Binary Pulsar System Psr J1023+0038

DOE PAGES

Stappers, B. W.; Archibald, A. M.; Hessels, J. W. T.; ...

2014-07-01

We present radio, X-ray, and γ-ray observations which reveal that the binary millisecond pulsar / low-mass X-ray binary transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently the system harbored a bright millisecond radio pulsar, the radio pulsations at frequencies between 300 to 5000MHz have now become undetectable. Concurrent with this radio disappearance, the γ-ray flux of the system has quintupled. We conclude that, though the radio pulsar is currently not detectable, the pulsar mechanism is still active and the pulsar wind, as well as a newly formed accretion disk, are together providing the necessary conditionsmore » to create the γ-ray increase. The system is the first example of a transient, compact, low-mass γ-ray binary and will continue to provide an exceptional test bed for better understanding the formation of millisecond pulsars as well as accretion onto neutron stars in general.« less

Automated cross-identifying radio to infrared surveys using the LRPY algorithm: a case study

NASA Astrophysics Data System (ADS)

Weston, S. D.; Seymour, N.; Gulyaev, S.; Norris, R. P.; Banfield, J.; Vaccari, M.; Hopkins, A. M.; Franzen, T. M. O.

2018-02-01

Cross-identifying complex radio sources with optical or infra red (IR) counterparts in surveys such as the Australia Telescope Large Area Survey (ATLAS) has traditionally been performed manually. However, with new surveys from the Australian Square Kilometre Array Pathfinder detecting many tens of millions of radio sources, such an approach is no longer feasible. This paper presents new software (LRPY - Likelihood Ratio in PYTHON) to automate the process of cross-identifying radio sources with catalogues at other wavelengths. LRPY implements the likelihood ratio (LR) technique with a modification to account for two galaxies contributing to a sole measured radio component. We demonstrate LRPY by applying it to ATLAS DR3 and a Spitzer-based multiwavelength fusion catalogue, identifying 3848 matched sources via our LR-based selection criteria. A subset of 1987 sources have flux density values for all IRAC bands which allow us to use criteria to distinguish between active galactic nuclei (AGNs) and star-forming galaxies (SFG). We find that 936 radio sources ( ≈ 47 per cent) meet both of the Lacy and Stern AGN selection criteria. Of the matched sources, 295 have spectroscopic redshifts and we examine the radio to IR flux ratio versus redshift, proposing an AGN selection criterion below the Elvis radio-loud AGN limit for this dataset. Taking the union of all three AGNs selection criteria we identify 956 as AGNs ( ≈ 48 per cent). From this dataset, we find a decreasing fraction of AGNs with lower radio flux densities consistent with other results in the literature.

JVLA 1.5 GHz Continuum Observation of CLASH Clusters. I. Radio Properties of the BCGs

NASA Astrophysics Data System (ADS)

Yu, Heng; Tozzi, Paolo; van Weeren, Reinout; Liuzzo, Elisabetta; Giovannini, Gabriele; Donahue, Megan; Balestra, Italo; Rosati, Piero; Aravena, Manuel

2018-02-01

We present high-resolution (∼1″), 1.5 GHz continuum observations of the brightest cluster galaxies (BCGs) of 13 CLASH (Cluster Lensing And Supernova survey with Hubble) clusters at 0.18< z< 0.69 with the Karl G. Jansky Very Large Array (JVLA). Radio emission is clearly detected and characterized for 11 BCGs, while for two of them we obtain only upper limits to their radio flux (< 0.1 mJy at 5σ confidence level). We also consider five additional clusters whose BCG is detected in FIRST or NVSS. We find radio powers in the range from 2× {10}23 to ∼ {10}26 {{W}} {{Hz}}-1 and radio spectral indices {α }1.530 (defined as the slope between 1.5 and 30 GHz) distributed from ∼ -1 to ‑0.25 around the central value < α > =-0.68. The radio emission from the BCGs is resolved in three cases (Abell 383, MACS J1931, and RX J2129), and unresolved or marginally resolved in the remaining eight cases observed with JVLA. In all the cases the BCGs are consistent with being powered by active galactic nuclei. The radio power shows a positive correlation with the BCG star formation rate, and a negative correlation with the central entropy of the surrounding intracluster medium (ICM) except in two cases (MACS J1206 and CL J1226). Finally, over the restricted range in radio power sampled by the CLASH BCGs, we observe a significant scatter between the radio power and the average mechanical power stored in the ICM cavities.

Software Defined Radio Standard Architecture and its Application to NASA Space Missions

NASA Technical Reports Server (NTRS)

Andro, Monty; Reinhart, Richard C.

2006-01-01

A software defined radio (SDR) architecture used in space-based platforms proposes to standardize certain aspects of radio development such as interface definitions, functional control and execution, and application software and firmware development. NASA has charted a team to develop an open software defined radio hardware and software architecture to support NASA missions and determine the viability of an Agency-wide Standard. A draft concept of the proposed standard has been released and discussed among organizations in the SDR community. Appropriate leveraging of the JTRS SCA, OMG's SWRadio Architecture and other aspects are considered. A standard radio architecture offers potential value by employing common waveform software instantiation, operation, testing and software maintenance. While software defined radios offer greater flexibility, they also poses challenges to the radio development for the space environment in terms of size, mass and power consumption and available technology. An SDR architecture for space must recognize and address the constraints of space flight hardware, and systems along with flight heritage and culture. NASA is actively participating in the development of technology and standards related to software defined radios. As NASA considers a standard radio architecture for space communications, input and coordination from government agencies, the industry, academia, and standards bodies is key to a successful architecture. The unique aspects of space require thorough investigation of relevant terrestrial technologies properly adapted to space. The talk will describe NASA's current effort to investigate SDR applications to space missions and a brief overview of a candidate architecture under consideration for space based platforms.

Electronically shielded solid state charged particle detector

DOEpatents

Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.

1996-08-20

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite. 1 fig.

Electronically shielded solid state charged particle detector

DOEpatents

Balmer, David K.; Haverty, Thomas W.; Nordin, Carl W.; Tyree, William H.

1996-08-20

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite.

Accretion and Outflows in X-ray Binaries: What's Really Going on During X-ray Quiescence

NASA Astrophysics Data System (ADS)

MacDonald, Rachel K. D.; Bailyn, Charles D.; Buxton, Michelle

2015-01-01

X-ray binaries, consisting of a star and a stellar-mass black hole, are wonderful laboratories for studying accretion and outflows. They evolve on timescales quite accessible to us, unlike their supermassive cousins, and allow the possibility of gaining a deeper understanding of these two common astrophysical processes. Different wavelength regimes reveal different aspects of the systems: radio emission is largely generated by outflows and jets, X-ray emission by inner accretion flows, and optical/infrared (OIR) emission by the outer disk and companion star. The search for relationships between these different wavelengths is thus an area of active research, aiming to reveal deeper connections between accretion and outflows.Initial evidence for a strong, tight correlation between radio and X-ray emission has weakened as further observations and newly-discovered sources have been obtained. This has led to discussions of multiple tracks or clusters, or the possibility that no overall relation exists for the currently-known population of X-ray binaries. Our ability to distinguish among these options is hampered by a relative lack of observations at lower luminosities, and especially of truly X-ray quiescent (non-outbursting) systems. Although X-ray binaries spend the bulk of their existence in quiescence, few quiescent sources have been observed and multiple observations of individual sources are largely nonexistent. Here we discuss new observations of the lowest-luminosity quiescent X-ray binary, A0620-00, and the place this object occupies in investigations of the radio/X-ray plane. For the first time, we also incorporate simultaneous OIR data with the radio and X-ray data.In December 2013 we took simultaneous observations of A0620-00 in the X-ray (Chandra), the radio (EVLA), and the OIR (SMARTS 1.3m). These X-ray and radio data allowed us to investigate similarities among quiescent X-ray binaries, and changes over time for this individual object, in the radio/X-ray plane. In addition, our OIR observations allowed us to examine the radio and X-ray information in relation to the different OIR states of behavior (passive and active) known to exist during X-ray quiescence.

PARTNeR for Teaching and Learning Radio Astronomy Basics

NASA Astrophysics Data System (ADS)

Vaquerizo, Juan Ángel

2010-10-01

NASA has three satellite tracking stations around the world: CDSCC (Canberra, Australia), GDSCC (Goldstone, USA) and MDSCC (Madrid, Spain). One of the antennas located at MDSCC, DSS-61, is not used for satellite tracking any more and thanks to an agreement between INTA (Instituto Nacional de TA~l'cnica Aeroespacial) and NASA, it has been turned into an educational radio telescope. PARTNeR (Proyecto Académico con el RadioTelescopio de NASA en Robledo, Academic Project with the NASA Radio Telescope at Robledo) is a High School and University radio astronomy educational program that allows teachers and students to control this 34-meter radio telescope and conduct radio astronomical observations via the Internet. As radio astronomy is not a popular subject and astronomy has little presence in the High School Curriculum, teachers need specific training in those subjects to implement PARTNeR. Thus, High School teachers joining the project take a course to learn about the science of radio astronomy and how to use the antenna in their classrooms. Also, teachers are provided with some learning activities they can do with their students. These lesson plans are focused on the implementation of the project within an interdisciplinary framework. All educational resources are available on PARTNeR website. PARTNeR is an inquiry based approach to science education. Nowadays, students can join in three different observational programmes: variability studies in quasars, studies of radio-bursts in X-ray binaries (microquasars), and mapping of radio sources in the galactic plane. Nevertheless, any other project can be held after an evaluation by the scientific committee. The operational phase of the project started in the academic year 2003-04. Since then, 85 High Schools, seven Universities and six societies of amateur astronomers have been involved in the project. During the 2004-09 period, 103 High School teachers from Spain and Portugal have attended the training courses, and 105 radio astronomical remote observations have been performed with users. Until now, more than 2,000 students have been involved in radio astronomical observations.

Multifrequency studies of the narrow-line Seyfert 1 galaxy SBS 0846+513

DOE PAGES

D'Ammando, F.; Orienti, M.; Finke, J.; ...

2013-09-16

Here, the narrow-line Seyfert 1 galaxy SBS 0846+513 was first detected by the Large Area Telescope on board Fermi in 2011 June–July when it underwent a period of flaring activity. Since then, as Fermi continues to accumulate data on this source, its flux has been monitored on a daily basis. Two further γ-ray flaring episodes from SBS 0846+513 were observed in 2012 May and August, reaching a daily peak flux integrated above 100 MeV of (50 ± 12) × 10 –8 ph cm –2 s –1, and (73 ± 14) × 10 –8 ph cm –2 s –1 on Maymore » 24 and August 7, respectively. Three outbursts were detected at 15 GHz by the Owens Valley Radio Observatory 40 m telescope in 2012 May, 2012 October and 2013 January, suggesting a complex connection with the γ-ray activity. The most likely scenario suggests that the 2012 May γ-ray flare may not be directly related to the radio activity observed over the same period, while the two γ-ray flaring episodes may be related to the radio activity observed at 15 GHz in 2012 October and 2013 January. The γ-ray flare in 2012 May triggered Swift observations that confirmed that SBS 0846+513 was also exhibiting high activity in the optical, UV and X-ray bands, thus providing a firm identification between the γ-ray source and the lower energy counterpart. We compared the spectral energy distribution (SED) of the flaring state in 2012 May with that of a quiescent state. The two SEDs, modelled as an external Compton component of seed photons from a dust torus, could be fitted by changing the electron distribution parameters as well as the magnetic field. No significant evidence of thermal emission from the accretion disc has been observed. Interestingly, in the 5 GHz radio luminosity versus synchrotron peak frequency plot SBS 0846+513 seems to lie in the flat spectrum radio quasar part of the so-called ‘blazar sequence’.« less

Fornax A, Centaurus A other radio galaxies as sources of ultra-high energy cosmic rays

NASA Astrophysics Data System (ADS)

Matthews, J. H.; Bell, A. R.; Blundell, K. M.; Araudo, A. T.

2018-06-01

The origin of ultra-high energy cosmic rays (UHECRs) is still unknown. It has recently been proposed that UHECR anisotropies can be attributed to starburst galaxies or active galactic nuclei. We suggest that the latter is more likely and that giant-lobed radio galaxies such as Centaurus A and Fornax A can explain the data.

Boundary Layer Remote Sensing with Combined Active and Passive Techniques: GPS Radio Occultation and High-Resolution Stereo Imaging (WindCam) Small Satellite Concept

NASA Technical Reports Server (NTRS)

Mannucci, A.J.; Wu, D.L.; Teixeira, J.; Ao, C.O.; Xie, F.; Diner, D.J.; Wood, R.; Turk, Joe

2012-01-01

Objective: significant progress in understanding low-cloud boundary layer processes. This is the Single largest uncertainty in climate projections. Radio occultation has unique features suited to boundary layer remote sensing (1) Cloud penetrating (2) Very high vertical resolution (approximately 50m-100m) (3) Sensitivity to thermodynamic variables

[Activities of Texas University

NASA Technical Reports Server (NTRS)

Oliversen, R. (Technical Monitor); Wills, Beverley J.; Wills, D.

2003-01-01

All the principal investigator's current projects investigate aspects of radio-loud, radio-quiet, BAL QSOs, and buried (IRAS-selected) QSOs and the relationships among these different classes, with the aim of probing the nature of accretion onto the massive central black hole - via relativistic jets, X-ray and optical absorption outflows, and the kinematics of the surrounding gas whose emission lines are excited by the accretion continuum.

SOME APPLICATIONS TO TELEVISION AND RADIO TO THE TEACHING OF ENGLISH AS A SECOND LANGUAGE IN NORTHERN NIGERIA.

ERIC Educational Resources Information Center

KINCAID, R. THOMAS

THIS REPORT PRESENTS A DESCRIPTION OF THE ACTIVITIES, ACCOMPLISHMENTS, HOST GOVERNMENT CONTRIBUTIONS, PROBLEMS, AND RECOMMENDATIONS MADE CONCERNING THE TWO-YEAR PROJECT (NOVEMBER 1, 1966 TO 1967) IN WHICH TELEVISION AND RADIO WERE USED AS MEDIA FOR TEACHING ENGLISH AS A SECOND LANGUAGE IN NORTHERN NIGERIA. A SERIES OF TELECASTS (EIGHT 20-MINUTE…

1997 Technology Applications Report,

DTIC Science & Technology

1997-01-01

handle high -power loads at microwave radio frequencies , microwave vacuum tubes remain the chosen technology to amplify high power. Aria Microwave...structure called the active RF cavity amplifier (ARFCA). With this design , the amplifier handles high -power loads at radio and microwave frequencies ...developed this technology using BMDO-funded modeling methods designed to simulate the dynamics of large space-based structures. Because it increases

13. VIEW OF CONTROL CONSOLE CURRENTLY USED ON OCCASION FOR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. VIEW OF CONTROL CONSOLE CURRENTLY USED ON OCCASION FOR AMATUER RADIO AND TO PERIODICALLY ACTIVE STATION KPS. NOTE CLOCK ON WALL. SHADED PORTIONS ON 24HR CLOCK (15-18 AND 45-48 MINUTES) INDICATED MINUTES EACH HOUR WHEN STATIONS WOULD NOT TRANSMIT AND LISTEN FOR WEAK DISTRESS SIGNALS. - Marconi Radio Sites, Receiving, Point Reyes Station, Marin County, CA

Exploring the Variability of the Flat-spectrum Radio Source 1633+382. II. Physical Properties

NASA Astrophysics Data System (ADS)

Algaba, Juan-Carlos; Lee, Sang-Sung; Rani, Bindu; Kim, Dae-Won; Kino, Motoki; Hodgson, Jeffrey; Zhao, Guang-Yao; Byun, Do-Young; Gurwell, Mark; Kang, Sin-Cheol; Kim, Jae-Young; Kim, Jeong-Sook; Kim, Soon-Wook; Park, Jong-Ho; Trippe, Sascha; Wajima, Kiyoaki

2018-06-01

The flat-spectrum radio quasar 1633+382 (4C 38.41) showed a significant increase of its radio flux density during the period 2012 March–2015 August, which correlates with γ-ray flaring activity. Multi-frequency simultaneous very long baseline interferometry (VLBI) observations were conducted as part of the interferometric monitoring of gamma-ray bright active galactic nuclei (iMOGABA) program and supplemented with additional radio monitoring observations with the OVRO 40 m telescope, the Boston University VLBI program, and the Submillimeter Array. The epochs of the maxima for the two largest γ-ray flares coincide with the ejection of two respective new VLBI components. Analysis of the spectral energy distribution indicates a higher turnover frequency after the flaring events. The evolution of the flare in the turnover frequency-turnover flux density plane probes the adiabatic losses in agreement with the shock-in-jet model. The derived synchrotron self-absorption magnetic fields, of the order of 0.1 mG, do not seem to change dramatically during the flares, and are much weaker, by a factor 104, than the estimated equipartition magnetic fields, indicating that the source of the flare may be associated with a particle-dominated emitting region.

N V Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) yesterday, today, tomorrow

NASA Astrophysics Data System (ADS)

Kuznetsov, V. D.

2015-06-01

This paper describes the basic and applied research rationale for the organization of IZMIRAN and provides insight into the 75 years of the Institute's activities and development. Historically, early magnetic measurements in Russia were developed largely to meet the Navy's navigation needs and were, more generally, stimulated by the Peter the Great decrees and by the foundation of the St. Petersburg Academy of Sciences in 1724. The paper examines the roles of the early Academicians in developing geomagnetism and making magnetic measurements a common practice in Russia. The need for stable radio communications prompted ionospheric and radio wave propagation research. The advent of the space era and the 1957-1958 International Geophysical Year Project greatly impacted the development of IZMIRAN and spurred the creation of a number of geophysical research institutes throughout the country. Currently, the research topics at IZMIRAN range widely from geomagnetism to solar-terrestrial physics to the ionosphere and radio wave propagation, and its primary application areas are the study and forecast of space weather, an increasingly important determining factor in ever-expanding ground- and space-based technologies (space navigation and communications, space activities, etc.).

RAiSE III: 3C radio AGN energetics and composition

NASA Astrophysics Data System (ADS)

Turner, Ross J.; Shabala, Stanislav S.; Krause, Martin G. H.

2018-03-01

Kinetic jet power estimates based exclusively on observed monochromatic radio luminosities are highly uncertain due to confounding variables and a lack of knowledge about some aspects of the physics of active galactic nuclei (AGNs). We propose a new methodology to calculate the jet powers of the largest, most powerful radio sources based on combinations of their size, lobe luminosity, and shape of their radio spectrum; this approach avoids the uncertainties encountered by previous relationships. The outputs of our model are calibrated using hydrodynamical simulations and tested against independent X-ray inverse-Compton measurements. The jet powers and lobe magnetic field strengths of radio sources are found to be recovered using solely the lobe luminosity and spectral curvature, enabling the intrinsic properties of unresolved high-redshift sources to be inferred. By contrast, the radio source ages cannot be estimated without knowledge of the lobe volumes. The monochromatic lobe luminosity alone is incapable of accurately estimating the jet power or source age without knowledge of the lobe magnetic field strength and size, respectively. We find that, on average, the lobes of the Third Cambridge Catalogue of Radio Sources (3C) have magnetic field strengths approximately a factor three lower than the equipartition value, inconsistent with equal energy in the particles and the fields at the 5σ level. The particle content of 3C radio lobes is discussed in the context of complementary observations; we do not find evidence favouring an energetically dominant proton population.

Juno Listens to Jupiter Auroras Sing

NASA Image and Video Library

2016-09-02

During its close flyby of Jupiter on August 27, 2016, the Waves instrument on NASA's Juno spacecraft received radio signals associated with the giant planet's very intense auroras. This video displays these radio emissions in a format similar to a voiceprint, showing the intensity of radio waves as a function of frequency and time. The largest intensities are indicated in warmer colors. The frequency range of these signals is from 7 to 140 kilohertz. Radio astronomers call these "kilometric emissions" because their wavelengths are about a kilometer long. The time span of this data is 13 hours, beginning shortly after Juno's closest approach to Jupiter. Accompanying this data display is an audio rendition of the radio emissions, shifted into a lower register since the radio waves are well above the audio frequency range. In the video, a cursor moves from left to right to mark the time as the sounds are heard. These radio emissions were among the first observed by early radio astronomers in the 1950s. However, until now, they had not been observed from closely above the auroras themselves. From its polar orbit vantage point, Juno has -- for the first time -- enabled observations of these emissions from very close range. The Juno team believes that Juno flew directly through the source regions for some of these emissions during this flyby, which was Juno's first with its sensors actively collecting data. A movie is available at http://photojournal.jpl.nasa.gov/catalog/PIA21037

The Radio-Loud Narrow-Line Quasar SDSS J172206.03+565451.6

NASA Astrophysics Data System (ADS)

Komossa, Stefanie; Voges, Wolfgang; Adorf, Hans-Martin; Xu, Dawei; Mathur, Smita; Anderson, Scott F.

2006-03-01

We report identification of the radio-loud narrow-line quasar SDSS J172206.03+565451.6, which we found in the course of a search for radio-loud narrow-line active galactic nuclei (AGNs). SDSS J172206.03+565451.6 is only about the fourth securely identified radio-loud narrow-line quasar and the second-most radio loud, with a radio index R1.4~100-700. Its black hole mass, MBH~=(2-3)×107 Msolar estimated from Hβ line width and 5100 Å luminosity, is unusually small given its radio loudness, and the combination of mass and radio index puts SDSS J172206.03+565451.6 in a scarcely populated region of MBH-R diagrams. SDSS J172206.03+565451.6 is a classical narrow-line Seyfert 1-type object with FWHMHβ~=1490 km s-1, an intensity ratio of [O III]/Hβ~=0.7, and Fe II emission complexes with Fe II λ4570/Hβ~=0.7. The ionization parameter of its narrow-line region, estimated from the line ratio [O II]/[O III], is similar to Seyferts, and its high ratio of [Ne V]/[Ne III] indicates a strong EUV-to-soft X-ray excess. We advertise the combined usage of [O II]/[O III] and [Ne V]/[Ne III] diagrams as a useful diagnostic tool to estimate ionization parameters and to constrain the EUV-soft X-ray continuum shape relatively independently from other parameters.

Engendering Climate Information Networks in Africa: Case Studies of Digital and FM Radio for Disseminating Disaster Early Warnings to Women and Youth

NASA Astrophysics Data System (ADS)

Stewart, M. M.; Pratt, M.

2002-05-01

This paper examines the effectiveness of FM and digital radio in disseminating weather and climate information to remote rural populations in Niger and Uganda. In Niger, poor communications infrastructure necessitated the establishment of a basic radio system as a first step towards disseminating climate information. Dissemination via digital radio is limited, in this context, by lack of technical support and the difficulty of maintaining computer equipment in the hot and dusty climate. Community FM stations have supported a range of mitigation activities that reduced vulnerability in all sites studied. Digital radio proved a more effective tool for disseminating climate information in Uganda, where technical knowledge is more prevalent and infrastructure networks are stronger. The primary challenge in Uganda lies in maintaining equipment in remote locations and disseminating information to a wider audience by linking with FM radio. Climate and weather information is already demonstrating positive impacts on agricultural production in Uganda, health and civil society in Niger, and on vulnerability reduction in both countries. Radio,particularly FM, was an excellent medium for disseminating information to women, youth, and other hard to reach populations. Discussion will focus on recommendations for improving the effectiveness of both systems and for practically linking FM and digital dissemination systems for better communication of climate information. Implications of the case studies will also be discussed in the context of digital and FM radio as media for disseminating other types of scientific information.

A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN Hosted by NGC 404

NASA Astrophysics Data System (ADS)

Nyland, Kristina; Davis, Timothy A.; Nguyen, Dieu D.; Seth, Anil; Wrobel, Joan M.; Kamble, Atish; Lacy, Mark; Alatalo, Katherine; Karovska, Margarita; Maksym, W. Peter; Mukherjee, Dipanjan; Young, Lisa M.

2017-08-01

The nearby dwarf galaxy NGC 404 harbors a low-luminosity active galactic nucleus powered by the lowest-mass (<150,000 M ⊙) central massive black hole (MBH), with a dynamical mass constraint, currently known, thus providing a rare low-redshift analog to the MBH “seeds” that formed in the early universe. Here, we present new imaging of the nucleus of NGC 404 at 12-18 GHz with the Karl G. Jansky Very Large Array (VLA) and observations of the CO(2-1) line with the Atacama Large Millimeter/Submillimeter Array (ALMA). For the first time, we have successfully resolved the nuclear radio emission, revealing a centrally peaked, extended source spanning 17 pc. Combined with previous VLA observations, our new data place a tight constraint on the radio spectral index and indicate an optically thin synchrotron origin for the emission. The peak of the resolved radio source coincides with the dynamical center of NGC 404, the center of a rotating disk of molecular gas, and the position of a compact, hard X-ray source. We also present evidence for shocks in the NGC 404 nucleus from archival narrowband HST imaging, Chandra X-ray data, and Spitzer mid-infrared spectroscopy, and discuss possible origins for the shock excitation. Given the morphology, location, and steep spectral index of the resolved radio source, as well as constraints on nuclear star formation from the ALMA CO(2-1) data, we find the most likely scenario for the origin of the radio source in the center of NGC 404 to be a radio outflow associated with a confined jet driven by the active nucleus.

A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN Hosted by NGC 404

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nyland, Kristina; Lacy, Mark; Davis, Timothy A.

The nearby dwarf galaxy NGC 404 harbors a low-luminosity active galactic nucleus powered by the lowest-mass (<150,000 M {sub ⊙}) central massive black hole (MBH), with a dynamical mass constraint, currently known, thus providing a rare low-redshift analog to the MBH “seeds” that formed in the early universe. Here, we present new imaging of the nucleus of NGC 404 at 12–18 GHz with the Karl G. Jansky Very Large Array (VLA) and observations of the CO(2–1) line with the Atacama Large Millimeter/Submillimeter Array (ALMA). For the first time, we have successfully resolved the nuclear radio emission, revealing a centrally peaked,more » extended source spanning 17 pc. Combined with previous VLA observations, our new data place a tight constraint on the radio spectral index and indicate an optically thin synchrotron origin for the emission. The peak of the resolved radio source coincides with the dynamical center of NGC 404, the center of a rotating disk of molecular gas, and the position of a compact, hard X-ray source. We also present evidence for shocks in the NGC 404 nucleus from archival narrowband HST imaging, Chandra X-ray data, and Spitzer mid-infrared spectroscopy, and discuss possible origins for the shock excitation. Given the morphology, location, and steep spectral index of the resolved radio source, as well as constraints on nuclear star formation from the ALMA CO(2–1) data, we find the most likely scenario for the origin of the radio source in the center of NGC 404 to be a radio outflow associated with a confined jet driven by the active nucleus.« less

VARIABLE AND POLARIZED RADIO EMISSION FROM THE T6 BROWN DWARF WISEP J112254.73+255021.5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, P. K. G.; Berger, E.; Gizis, J. E., E-mail: pwilliams@cfa.harvard.edu

2017-01-10

Route and Wolszczan recently detected five radio bursts from the T6 dwarf WISEP J112254.73+255021.5 and used the timing of these events to propose that this object rotates with an ultra-short period of ∼17.3 minutes. We conducted follow-up observations with the Very Large Array and Gemini-North but found no evidence for this periodicity. We do, however, observe variable, highly circularly polarized radio emission. Assuming that the radio emission of this T dwarf is periodically variable on ∼hour timescales, like other radio-active ultracool dwarfs, we infer a likely period of 116 minutes. However, our observation lasted only 162 minutes and so more data are needed to test thismore » hypothesis. The handedness of the circular polarization switches twice and there is no evidence for any unpolarized emission component, the first time such a phenomenology has been observed in radio studies of very low-mass stars and brown dwarfs. We suggest that the object’s magnetic dipole axis may be highly misaligned relative to its rotation axis.« less

Li/BCX (thionyl chloride) battery for the NASA AN/PRC-112 survival radio

NASA Astrophysics Data System (ADS)

Ebel, Steven J.; Clark, W. D. K.; Eberhard, D. P.; Darcy, Eric C.

1992-02-01

As part of the NASA contingency planning related to aborting a launch after liftoff, an emergency radio is required for use by the crew when they return to Earth at some unplanned location. The power source for the radio must be able to satisfy the performance requirements for the radio's mission as well as be compatible with in-cabin storage in the space shuttle. The radio needs a base load power of about 1 W with capability to handle power spikes greater then 6.5 W. A slightly enlarged battery pack using the Li/BCX chemistry in C-size cells was developed that meets these power levels and extends the operational life of the radio by over a factor of four compared to its operation using a Li/SO2 cell battery pack. In addition, the cells meet the requirements for the Li/BCX cells used for extra-vehicular activities by the crew of the shuttle. One of the major qualifying tests is the ability of the cells to withstand exposure to high temperature (149 C) without leaking. Electrical performance and thermal abuse test data will be presented for the cells.

Li/BCX (thionyl chloride) battery for the NASA AN/PRC-112 survival radio

NASA Technical Reports Server (NTRS)

Ebel, Steven J.; Clark, W. D. K.; Eberhard, D. P.; Darcy, Eric C.

1992-01-01

As part of the NASA contingency planning related to aborting a launch after liftoff, an emergency radio is required for use by the crew when they return to Earth at some unplanned location. The power source for the radio must be able to satisfy the performance requirements for the radio's mission as well as be compatible with in-cabin storage in the space shuttle. The radio needs a base load power of about 1 W with capability to handle power spikes greater then 6.5 W. A slightly enlarged battery pack using the Li/BCX chemistry in C-size cells was developed that meets these power levels and extends the operational life of the radio by over a factor of four compared to its operation using a Li/SO2 cell battery pack. In addition, the cells meet the requirements for the Li/BCX cells used for extra-vehicular activities by the crew of the shuttle. One of the major qualifying tests is the ability of the cells to withstand exposure to high temperature (149 C) without leaking. Electrical performance and thermal abuse test data will be presented for the cells.

Radio Occultation Experiments with Venus Express and Mars Express using the Planetary Radio Interferometry and Doppler Experiment (PRIDE) Technique

NASA Astrophysics Data System (ADS)

Bocanegra Bahamon, T.; Gurvits, L.; Molera Calves, G.; Cimo, G.; Duev, D.; Pogrebenko, S.; Dirkx, D.; Rosenblatt, P.

2017-12-01

The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that can be used to enhance multiple radio science experiments of planetary missions. By 'eavesdropping' on the spacecraft signal using radio telescopes from different VLBI networks around the world, the PRIDE technique provides precise open-loop Doppler and VLBI observables to able to reconstruct the spacecraft's orbit. The application of this technique for atmospheric studies has been assessed by observing ESA's Venus Express (VEX) and Mars Express (MEX) during multiple Venus and Mars occultation events between 2012 and 2014. From these observing sessions density, temperature and pressure profiles of Venus and Mars neutral atmosphere and ionosphere have been retrieved. We present an error propagation analysis where the uncertainties of the atmospheric properties measured with this technique have been derived. These activities serve as demonstration of the applicability of the PRIDE technique for radio occultation studies, and provides a benchmark against the traditional Doppler tracking provided by the NASA's DSN and ESA's Estrack networks for these same purposes, in the framework of the upcoming ESA JUICE mission to the Jovian system.

High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars

DOE PAGES

Giroletti, M.; Massaro, F.; D’Abrusco, R.; ...

2016-04-01

Low-frequency radio arrays are opening a new window for the study of the sky, both to study new phenomena and to better characterize known source classes. Being flat-spectrum sources, blazars are so far poorly studied at low radio frequencies. In this paper, we characterize the spectral properties of the blazar population at low radio frequency, compare the radio and high-energy properties of the gamma-ray blazar population, and search for radio counterparts of unidentified gamma-ray sources. We cross-correlated the 6100 deg 2 Murchison Widefield Array Commissioning Survey catalogue with the Roma blazar catalogue, the third catalogue of active galactic nuclei detectedmore » by Fermi-LAT, and the unidentified members of the entire third catalogue of gamma-ray sources detected by Fermi-LAT. When available, we also added high-frequency radio data from the Australia Telescope 20 GHz catalogue. We find low-frequency counterparts for 186 out of 517 (36%) blazars, 79 out of 174 (45%) gamma-ray blazars, and 8 out of 73 (11%) gamma-ray blazar candidates. The mean low-frequency (120–180 MHz) blazar spectral index is (α low) = 0.57 ± 0.02: blazar spectra are flatter than the rest of the population of low-frequency sources, but are steeper than at ~GHz frequencies. Low-frequency radio flux density and gamma-ray energy flux display a mildly significant and broadly scattered correlation. Ten unidentified gamma-ray sources have a (probably fortuitous) positional match with low radio frequency sources. Low-frequency radio astronomy provides important information about sources with a flat radio spectrum and high energy. However, the relatively low sensitivity of the present surveys still misses a significant fraction of these objects. Finally, upcoming deeper surveys, such as the GaLactic and Extragalactic All-Sky MWA (GLEAM) survey, will provide further insight into this population.« less

CAVITIES AND SHOCKS IN THE GALAXY GROUP HCG 62 AS REVEALED BY CHANDRA, XMM-NEWTON, AND GIANT METREWAVE RADIO TELESCOPE DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitti, Myriam; O'Sullivan, Ewan; Giacintucci, Simona

2010-05-01

We report on the results of an analysis of Chandra, XMM-Newton, and new Giant Metrewave Radio Telescope (GMRT) data of the X-ray bright compact group of galaxies HCG 62, which is one of the few groups known to possess clear, small X-ray cavities in the inner regions. This is part of an ongoing X-ray/low-frequency radio study of 18 groups, initially chosen for the availability of good-quality X-ray data and evidence for active galactic nucleus/hot gas interaction. At higher frequency (1.4 GHz), the HCG 62 cavity system shows minimal if any radio emission, but the new GMRT observations at 235 MHzmore » and 610 MHz clearly detect extended low-frequency emission from radio lobes corresponding to the cavities. By means of the synergy of X-ray and low-frequency radio observations, we compare and discuss the morphology, luminosity, and pressure of the gas and of the radio source. We find that the radio source is radiatively inefficient, with a ratio of radio luminosity to mechanical cavity power of {approx}10{sup -4}, and that the radio pressure of the lobes is about 1 order of magnitude lower than the X-ray pressure of the surrounding thermal gas. Thanks to the high spatial resolution of the Chandra surface brightness and temperature profiles, we also identify a shock front located at 36 kpc to the southwest of the group center, close to the southern radio lobe, with a Mach number {approx}1.5 and a total power which is about 1 order of magnitude higher than the cavity power. Such a shock may have heated the gas in the southern region, as indicated by the temperature map. The shock may also explain the arc-like region of enriched gas seen in the iron abundance map, as this may be produced by a non-Maxwellian electron distribution near its front.« less

High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giroletti, M.; Massaro, F.; D’Abrusco, R.

Low-frequency radio arrays are opening a new window for the study of the sky, both to study new phenomena and to better characterize known source classes. Being flat-spectrum sources, blazars are so far poorly studied at low radio frequencies. In this paper, we characterize the spectral properties of the blazar population at low radio frequency, compare the radio and high-energy properties of the gamma-ray blazar population, and search for radio counterparts of unidentified gamma-ray sources. We cross-correlated the 6100 deg 2 Murchison Widefield Array Commissioning Survey catalogue with the Roma blazar catalogue, the third catalogue of active galactic nuclei detectedmore » by Fermi-LAT, and the unidentified members of the entire third catalogue of gamma-ray sources detected by Fermi-LAT. When available, we also added high-frequency radio data from the Australia Telescope 20 GHz catalogue. We find low-frequency counterparts for 186 out of 517 (36%) blazars, 79 out of 174 (45%) gamma-ray blazars, and 8 out of 73 (11%) gamma-ray blazar candidates. The mean low-frequency (120–180 MHz) blazar spectral index is (α low) = 0.57 ± 0.02: blazar spectra are flatter than the rest of the population of low-frequency sources, but are steeper than at ~GHz frequencies. Low-frequency radio flux density and gamma-ray energy flux display a mildly significant and broadly scattered correlation. Ten unidentified gamma-ray sources have a (probably fortuitous) positional match with low radio frequency sources. Low-frequency radio astronomy provides important information about sources with a flat radio spectrum and high energy. However, the relatively low sensitivity of the present surveys still misses a significant fraction of these objects. Finally, upcoming deeper surveys, such as the GaLactic and Extragalactic All-Sky MWA (GLEAM) survey, will provide further insight into this population.« less

Combined Radio and Space-Based Solar Observations: From Techniques to New Results - Preface

NASA Astrophysics Data System (ADS)

Kontar, Eduard P.; Nindos, Alexander

2018-06-01

The phenomena observed at the Sun have a variety of unique radio signatures that can be used to diagnose the processes in the solar atmosphere. The insights provided by radio observations are further enhanced when they are combined with observations from space-based telescopes. This Topical collection demonstrates the power of combination methodology at work and provides new results on i) type I solar radio bursts and thermal emission to study active regions; ii) type II and IV bursts to better understand the structure of coronal mass ejections; and iii) non-thermal gyro-synchrotron and/or type III bursts to improve the characterisation of particle acceleration in solar flares. The ongoing improvements in time, frequency, and spatial resolutions of ground-based telescopes reveal new levels in the complexity of solar phenomena and pose new questions.

A theory for narrow-banded radio bursts at Uranus - MHD surface waves as an energy driver

NASA Technical Reports Server (NTRS)

Farrell, W. M.; Curtis, S. A.; Desch, M. D.; Lepping, R. P.

1992-01-01

A possible scenario for the generation of the narrow-banded radio bursts detected at Uranus by the Voyager 2 planetary radio astronomy experiment is described. In order to account for the emission burstiness which occurs on time scales of hundreds of milliseconds, it is proposed that ULF magnetic surface turbulence generated at the frontside magnetopause propagates down the open/closed field line boundary and mode-converts to kinetic Alfven waves (KAW) deep within the polar cusp. The oscillating KAW potentials then drive a transient electron stream that creates the bursty radio emission. To substantiate these ideas, Voyager 2 magnetometer measurements of enhanced ULF magnetic activity at the frontside magnetopause are shown. It is demonstrated analytically that such magnetic turbulence should mode-convert deep in the cusp at a radial distance of 3 RU.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swarup, S.; Chatterjea, J.B.; Hosain, P.

Several Hb. E-thalassemia and a few other cases of hematological interest were subjected to radio-iron tests using tracer doses of only 0.035 plus or minus 0.005 mu c/kg. of bodyweight and gas-flow counter for assaying the radio-activity of the samples. Serum iron and hemoglobin iron concentrations; curves for plasma iron clearance and appearance of radio-iron in red cells, and the plasma iron and the red cell iron turnover rates were obtained by standard methods. The results showed an increased rate of plasma clearance but decreased utilization of iron by erythrocytes in Hb. E-thalassemia disease; plasma iron-clearance pattern was similar tomore » iron deficiency anemia but the red cell radio-iron uptake pattern bore similarity to aplastic anemia. This suggests that ineffective erythropoiesis contributes significantly to the causation of anemia in Hb. E-thalassemia disease. (auth)« less

Recent Progress in Active Antenna Designs for the Long Wavelength Array (LWA)

NASA Astrophysics Data System (ADS)

Hicks, B. C.; Stewart, K. P.; Paravastu, N.; Bradley, R. F.; Parashare, C. R.; Erickson, W. C.; Gross, C.; Polisensky, E.; Crane, P. C.; Ray, P. S.; Kassim, N. E.; Weiler, K. W.

2005-12-01

We present new designs for active antenna systems optimized for HF/VHF radio astronomy, ionospheric science, space weather, and other radio science applications. Active antenna designs have been developed and tested which satisfy the need for high linearity and stability while achieving Galactic background dominated noise levels. The presence of very strong terrestrial radio-frequency interference (RFI), and world-wide propagation at these frequencies require that the preamplifiers have very high dynamic range. Distortion products must be below the Galactic background level for RFI mitigation techniques to be successful. Individual antennas should have broad response patterns to cover most of the sky without pointing mechanisms, but with decreased sensitivity at low elevations. Ideal designs would also be immune to environmental effects such as temperature variations and precipitation. For projects such as the LWA, where thousands of receptors will be needed, they must also be robust, inexpensive, and easy to manufacture and install. We discuss high-performance designs that are optimized for cost-sensitive applications such as the LWA. Basic research in astronomy is supported by the Office of Naval Research.

Interferometric imaging of the high-redshift radio galaxy, 4C60.07: an SMA, Spitzer and VLA study reveals a binary AGN/starburst

NASA Astrophysics Data System (ADS)

Ivison, R. J.; Morrison, G. E.; Biggs, A. D.; Smail, Ian; Willner, S. P.; Gurwell, M. A.; Greve, T. R.; Stevens, J. A.; Ashby, M. L. N.

2008-11-01

High-resolution submillimetre (submm) imaging of the high-redshift radio galaxy (HzRG), 4C60.07, at z = 3.8, has revealed two dusty components of roughly equal integrated flux. Spitzer imaging shows that one of these components (`B') is coincident with an extremely red active galactic nucleus (AGN), offset by ~4arcsec (~30kpc) from the HzRG core. The other submm component (`A') - resolved by our synthesized beam and devoid of emission at 3.6-8.0μm - lies between `B' and the HzRG core. Since the radio galaxy was discovered via its extremely young, steep-spectrum radio lobes and the creation of these lobes was likely triggered by the interaction, we argue that we are witnessing an early-stage merger, prior to its eventual equilibrium state. The interaction is between the host galaxy of an actively fuelled black hole (BH) and a gas-rich starburst/AGN (`B') marked by the compact submm component and coincident with broad CO(4-3) emission. The second submm component (`A') is a plume of cold, dusty gas, associated with a narrow (~150kms-1) CO feature, and may represent a short-lived tidal structure. It has been claimed that HzRGs and submillimetre-selected galaxies (SMGs) differ only in the activity of their AGNs, but such complex submm morphologies are seen only rarely amongst SMGs, which are usually older, more relaxed systems. Our study has important implications: where a galaxy's gas reservoir is not aligned with its central BH, CO may be an unreliable probe of dynamical mass, affecting work on the co-assembly of BHs and host spheroids. Our data support the picture wherein close binary AGN are induced by mergers. They also raise the possibility that some supposedly jet-induced starbursts may have formed co-evally (yet independently of) the radio jets, both triggered by the same interaction. Finally, we note that the HzRG host would have gone unnoticed without its jets and its companion, so there may be many other unseen BHs at high redshift, lost in the sea of ~5 × 108 similarly bright Infrared Array Camera (IRAC) sources - sufficiently massive to drive a >1027-W radio source, yet practically invisible unless actively fuelled.

Q-Learning and p-persistent CSMA based rendezvous protocol for cognitive radio networks operating with shared spectrum activity

NASA Astrophysics Data System (ADS)

Watson, Clifton L.; Biswas, Subir

2014-06-01

With an increasing demand for spectrum, dynamic spectrum access (DSA) has been proposed as viable means for providing the flexibility and greater access to spectrum necessary to meet this demand. Within the DSA concept, unlicensed secondary users temporarily "borrow" or access licensed spectrum, while respecting the licensed primary user's rights to that spectrum. As key enablers for DSA, cognitive radios (CRs) are based on software-defined radios which allow them to sense, learn, and adapt to the spectrum environment. These radios can operate independently and rapidly switch channels. Thus, the initial setup and maintenance of cognitive radio networks are dependent upon the ability of CR nodes to find each other, in a process known as rendezvous, and create a link on a common channel for the exchange of data and control information. In this paper, we propose a novel rendezvous protocol, known as QLP, which is based on Q-learning and the p-persistent CSMA protocol. With the QLP protocol, CR nodes learn which channels are best for rendezvous and thus adapt their behavior to visit those channels more frequently. We demonstrate through simulation that the QLP protocol provides a rendevous capability for DSA environments with different dynamics of PU activity, while attempting to achieve the following performance goals: (1) minimize the average time-to-rendezvous, (2) maximize system throughput, (3) minimize primary user interference, and (4) minimize collisions among CR nodes.

Centaurus A: Source Populations in the Nearest Bright Elliptical

NASA Technical Reports Server (NTRS)

Mushotzky, Richard (Technical Monitor); Murray, Stephen S.

2003-01-01

The XMM/Newton observations of the nearby radio galaxy, Centaurus A, have proven to be a rich data set and has given us new insights into several important processes present in Centaurus A. A list of publications, conference proceedings, and conference abstracts related to these data are attached at the end of this document. We have used the XMM/Newton observations to study the interaction between the relativistic, radio emitting plasma emitted from active nuclei with the hot interstellar medium. Centaurus A is the nearest radio galaxy, so that we have been able to study these features at a linear resolution unattainable for any similar object.

The Disk-Jet Connection in Radio-Loud AGN: The X-Ray Perspective

NASA Technical Reports Server (NTRS)

Sambruna, Rita

2008-01-01

Unification schemes assume that radio-loud active galactic nuclei (AGN) contain an accretion disk and a relativistic jet perpendicular to the disk, and an obscuring molecular torus. The jet dominance decreases with larger viewing angles from blazars to Broad-Line and Narrow-Line Radio Galaxies. A fundamental question is how accretion and ejecta are related. The X-rays provide a convenient window to study these issues, as they originate in the innermost nuclear regions and penetrate large obscuring columns. I review the data, using observations by Chandra but also from other currently operating high-energy experiments. Synergy with the upcoming GLAST mission will also be highlighted.

[CII] emission from NGC 4258 with SOFIA/FIFI-LS

NASA Astrophysics Data System (ADS)

Fadda, Dario; Appleton, Philip N.; Diaz Santos, Tanio; Togi, Aditya; Ogle, Patrick

2018-06-01

We present the [CII]157.7μm map of the NGC 4258 (M106) galaxy obtained with the FIFI-LS spectrometer onboard SOFIA.M106 contains an active nucleus classified as type 1.9 Seyfert with a warped inner rotating disk of water-vapor masers which allowed for the first high accuracy measurements of the mass of a supermassive black hole in any galaxy. A relativistic jet is thought to be responsible for anomalous radio-continuum spiral arms, which appear several kpc from the center, and extend outwards through the outer disk. These arms do not correlate with the galaxy's underlying stellar spiral structure, and their presence suggest that in the past, the jet has strongly interacted with the galaxy's outer disk , exciting synchrotron radiation. Since that time, a new burst of activity seems to have occurred, creating a compact jet at the core of the galaxy, and two radio hotspots further out associated with optical "bow-shocks". The position angle of this new "active" jet is different from that needed to excited the outer radio arms, presumably because the jet has precessed, perhaps as a result of precession of the axis of the inner warped accretion disk.Our observations reveal three main sources of [CII] emission: two associated with large regions of gas at the ends of the active jet, and a third minor axis filament associated with linear clumps of star formation and dust seen in HST images offset from the nucleus. We combine the SOFIA observations with previous Spitzer mid-IR, Chandra X-ray and VLA radio observations to explore the nature of the detected [CII] emission. In regions along the northern active jet, we see a significant deficiency in the [CII]/FIR ratio, and higher ratios near the ends of the jet. This implies that the jet has changed the conditions of the gas along its length. In several places near the jet, the [CII] emission shows very broad lines, suggestive of enhanced turbulence. Additionally, the minor-axis filament we discovered may represent gas in-falling towards the nucleus perpendicular to the jet. The results provide clues about how radio jets in active galaxies can influence the star formation properties of their host galaxies.

Passive Thermal Design Approach for the Space Communications and Navigation (SCaN) Testbed Experiment on the International Space Station (ISS)

NASA Technical Reports Server (NTRS)

Siamidis, John; Yuko, Jim

2014-01-01

The Space Communications and Navigation (SCaN) Program Office at NASA Headquarters oversees all of NASAs space communications activities. SCaN manages and directs the ground-based facilities and services provided by the Deep Space Network (DSN), Near Earth Network (NEN), and the Space Network (SN). Through the SCaN Program Office, NASA GRC developed a Software Defined Radio (SDR) testbed experiment (SCaN testbed experiment) for use on the International Space Station (ISS). It is comprised of three different SDR radios, the Jet Propulsion Laboratory (JPL) radio, Harris Corporation radio, and the General Dynamics Corporation radio. The SCaN testbed experiment provides an on-orbit, adaptable, SDR Space Telecommunications Radio System (STRS) - based facility to conduct a suite of experiments to advance the Software Defined Radio, Space Telecommunications Radio Systems (STRS) standards, reduce risk (Technology Readiness Level (TRL) advancement) for candidate Constellation future space flight hardware software, and demonstrate space communication links critical to future NASA exploration missions. The SCaN testbed project provides NASA, industry, other Government agencies, and academic partners the opportunity to develop and field communications, navigation, and networking technologies in the laboratory and space environment based on reconfigurable, software defined radio platforms and the STRS Architecture.The SCaN testbed is resident on the P3 Express Logistics Carrier (ELC) on the exterior truss of the International Space Station (ISS). The SCaN testbed payload launched on the Japanese Aerospace Exploration Agency (JAXA) H-II Transfer Vehicle (HTV) and was installed on the ISS P3 ELC located on the inboard RAM P3 site. The daily operations and testing are managed out of NASA GRC in the Telescience Support Center (TSC).

The radio properties of infrared-faint radio sources

NASA Astrophysics Data System (ADS)

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.

Science Priorities of the RadioAstron Space VLBI Mission

NASA Astrophysics Data System (ADS)

Langston, Glen; Kardashev, N.; International Space VLBI Collaboration

2006-12-01

The main scientific goal of the RadioAstron Space VLBI mission is study of Active Galactic Nuclei (AGN), Masers and other astronomical objects with unprecedented angular resolution, up to few millionths of an arc-second. The resolution achieved with RadioAstron will allow study the following phenomena and problems: * Central engine of AGN and physical processes near super massive black holes providing an acceleration of cosmic rays size, velocity and shape of emitting region in the core, spectrum, polarization and variability of emitting components; * Cosmological models, dark matter and dark energy by studying dependence of above mentioned AGN's parameters with redshift, and by observing gravitational lensing; * Structure and dynamics of star and planets forming regions in our Galaxy and in AGN by studying maser and Mega maser radio emission; * Neutron (quark?) stars and black holes in our Galaxy, their structure and dynamics by VLBI and measurements of visibility scintillations, proper motions and parallaxes; * Structure and distribution of interstellar and interplanetary plasma by fringe visibility scintillations of pulsars; The RadioAstron mission uses the satellite SPECTR (astrophysical module), developed by Lavochkin Association of Russian Aviation and Space Agency (RASA). This module will be used in several other scientific missions. The total mass of the scientific payload is about 2500 kg, of which the unfolding parabolic 10-m radio astronomy antenna's mass is about 1500 kg, and scientific package holding the receivers, power supply, synthesizers, control units, frequency standards and data transmission radio system. The mass of the whole system (satellite and scientific payload) to be carried into orbit by the powerful "Zenit-2SB"-"Fregat-2CB" launcher is about 5000 kg. The RadioAstron project is an international collaboration between RASA and ground radio telescope facilities around the world.

Conceptual Background to Radio

NASA Astrophysics Data System (ADS)

Ponsonby, J. E. B.

2004-06-01

The International Telecommunications Union (ITU) conceives the radio spectrum as primarily a resource for telecommunications. Indeed most applications of radio are for communications and other radio services, particularly the Radio Astronomy Service, are deemed to be `pretend'communication serviceas for spectrum amnagement purposes. The language of Radio Spectrum Management is permeated by the terminology ofcommunications, some derived from the physics of radio and some from aspects of information theory. This contribution touches on all the essential concepts of radiocommunications which the author thinks should be the common mental equipment of the Spectrum Manager. The fundamental capacity of a communication channel is discussed in terms of the degrees of freedom and bandwidth of a signal, and the signal to noise ratio. It is emphasized that an information bearing signal is inherently unpredictable, and must, at some level, be discontinuous. This has important consequences for the form of its power spectrum. The effect of inserting filters is discussed particularly with regard to constant amplitude signals and, in the context of non-linear power amplifiers, the phenomenon of`sideband recovery'. All the common generic forms of modulation are discussed including the very different case of `no-modulation' which applies in all forms of passive remote sensing. Whilst all are agreed that the radio spectrum should be used `efficiently', there is no quantitative measure of spectral efficiency which embraces all relevant aspects of spectral usage. These various aspects are dicussed. Finally a brief outline of some aspects of antennae are reviewed. It is pointed out that the recent introduction of so-called `active antennnae', which have properties unlike traditional passive antennae, has confused the interpretation of those ITU Radio Regulations which refer to antennae.

Flaring Activity from S5 0836+71 (4C71.07): What Can We Learn with Limited Multiwavelength Coverage?

NASA Technical Reports Server (NTRS)

Thompson, D. J.; Donato, D.; Akyuz, A.; Fuhrmann, L.; Sokolovsky, K.; Kurtanidze, O.

2011-01-01

After a long period of quiescence in gamma rays, blazar S5 0836+71 (4C71.07) flared in the Spring of 2011. We found only limited multiwavelength coverage of the source. An indication of correlated optical/gamma-ray variability is not surprising for a FSRQ like this one. Radio observations at high frequencies, however, had seen a flare in late 2010, with no apparent related gamma-ray activity. This case seems to differ from the traditional pattern of finding gamma-ray flares during times of rising radio emission.

Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan

NASA Technical Reports Server (NTRS)

Marubashi, K.; Miyamoto, Y.; Kidokoro, T.; Ishii, T.

1979-01-01

The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.

SELF and VLF electromagnetic emissions that preceded the M6.2 Central Italy earthquake occurred on August 24, 2016

NASA Astrophysics Data System (ADS)

Cataldi, Daniele; Cataldi, Gabriele; Straser, Valentino

2017-04-01

On August 24, 2016 at 01:36:32 UTC a destructive earthquake hit Central Italy with a magnitude of M6.2. The authors of this study have recorded some electromagnetic signals that have preceded this strong earthquake. These signals were recorded through two electromagnetic monitoring stations realized by Gabriele Cataldi and Daniele Cataldi, located near the town of Albano Laziale (Rome, Italy) and near the city of Lariano (Rome, Italy) and can monitor the radio spectrum 24h7 between 0.001 Hz and 96 kHz (SELF-LF band). The electromagnetic monitoring allowed to identify two interesting types of electromagnetic anomalies: the first electromagnetic anomaly was recorded on August 18, 2016 between 02:47 UTC and 06:21 UTC, in the VLF band prevalently between 18kHz and 26kHz; the second electromagnetic anomaly was registered between 08:00 UTC on August 23, 2016 and 05:00 UTC on August 24, 2016, prevalently between 0.01 and 0.7Hz: the most intense signals were recorded at 08:50 UTC on August 23, 2016 and approximately 1 hour before the strong earthquake. The Earth's electromagnetic background monitoring in the SELF-VLF band (0Hz

Radio Observations of the Ionosphere From an Imaging Array and a CubeSat

NASA Astrophysics Data System (ADS)

Isham, B.; Gustavsson, B.; Bullett, T. W.; Bergman, J. E. S.; Rincón-Charris, A.; Bruhn, F.; Funk, P.

2017-12-01

The ionosphere is a source of many radio emissions in the various low-frequency, medium-frequency, and high-frequency bands (0 to 30 MHz). In addition to natural radio emissions, artificial emissions can be stimulated using high-power radiowave ionospheric modification facilities. Two complementary projects are underway for the purpose of improving our knowledge of the processes of radio emissions from the ionosphere. One project is the Aguadilla radio array, located in northwestern Puerto Rico. The Aguadilla array is intended to produce 2 to 25 MHz radio images of the ionosphere, as well as to perform bistatic radar imaging of the ionosphere over Puerto Rico. The array will consist of multiple antenna elements, each of which is a single active (electromagnetically short) crossed electric dipole. The elements are arranged within a roughly 200 by 300-meter core array, in a semi-random pattern providing an optimal distribution of baseline vectors, with 6-meter minimum spacing to eliminate spacial aliasing. In addition, several elements are arranged in a partial ring around the central core, providing a roughly four times expanded region in u-v space for improved image resolution and quality. Phase is maintained via cabled connections to a central location. A remote array is also being developed, in which phase is maintained between elements by through the use of GPS-disciplined rubidium clocks. The other project involves the GimmeRF radio instrument, designed for 0.3 to 30 MHz vector observation of the radio electric field, and planned for launch in 2020 on a CubeSat. The data rate that can be sustained by GimmeRF far exceeds any available communication strategy. By exploiting fast on-board computing and efficient artificial intelligence (AI) algorithms for analysis and data selection, the usage of the telemetry link can be optimized and value added to the mission. Radio images recorded by the radio array from below the ionosphere can be directly compared with the radio data received by GimmeRF in the topside ionosphere, with the goal of better understanding the geometry and therefore the mechanisms of the radio emission processes.

NRL SSD Research Achievements: 19801990. Volume 3

DTIC Science & Technology

2015-10-30

spectrum. Various ground based indices of solar activity, such as sunspot number, fluxes at various radio frequencies (F10.7 cm), and the total area and...standard for generating complex electro-optical (including limited Lidar) and radio frequency signature information. This signature information was...ADDRESS(ES) 11 . SPONSOR / MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION / AVAILABILITY STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS

Defense Logistics: DOD Has Addressed Most Reporting Requirements and Continues to Refine Its Asset Visibility Strategy

DTIC Science & Technology

2015-12-01

Development, Test, and Evaluation RFID Radio Frequency Identification SEP Supporting Execution Plan Strategy Strategy to Improve Asset...migration of active Radio Frequency Identification ( RFID )19 from a proprietary communication standard protocol to an international standard to...technologies enabling hands-off processing of materiel deploying through the Defense Transportation System. Materiel marked with RFID tags may be remotely

The Save-WEFM Case as Reported to the 50th Annual NAEB Convention, 1974.

ERIC Educational Resources Information Center

Danna, Sammy R.

The history of Chicago FM radio station WEFM and the activities of the Citizen's Committee to Save WEFM are chronicled. The focus is principally on the actions of the Citizen's Committee to prevent the conversion of the radio station from a classical music format to rock and roll offerings and to block the sale of the station by Zenith to GCC…

Amateur Radio on the International Space Station - the First Operational Payload on the ISS

NASA Astrophysics Data System (ADS)

Bauer, F. H.; McFadin, L.; Steiner, M.; Conley, C. L.

2002-01-01

As astronauts and cosmonauts have adapted to life on the International Space Station (ISS), they have found Amateur Radio and its connection to life on Earth to be a constant companion and a substantial psychological boost. Since its first use in November 2000, the first five expedition crews have utilized the amateur radio station in the FGB to talk to thousands of students in schools, to their families on Earth, and to amateur radio operators around the world. Early in the development of ISS, an international organization called ARISS (Amateur Radio on the International Space Station) was formed to coordinate the construction and operation of amateur radio (ham radio) equipment on ISS. ARISS represents a melding of the volunteer teams that have pioneered the development and use of amateur radio equipment on human spaceflight vehicles. The Shuttle/Space Amateur Radio Experiment (SAREX) team enabled Owen Garriott to become the first astronaut ham to use amateur radio from space in 1983. Since then, amateur radio teams in the U.S. (SAREX), Germany, (SAFEX), and Russia (Mirex) have led the development and operation of amateur radio equipment on board NASA's Space Shuttle, Russia's Mir space station, and the International Space Station. The primary goals of the ARISS program are fourfold: 1) educational outreach through crew contacts with schools, 2) random contacts with the Amateur Radio public, 3) scheduled contacts with the astronauts' friends and families and 4) ISS-based communications experimentation. To date, over 65 schools have been selected from around the world for scheduled contacts with the orbiting ISS crew. Ten or more students at each school ask the astronauts questions, and the nature of these contacts embodies the primary goal of the ARISS program, -- to excite student's interest in science, technology and amateur radio. The ARISS team has developed various hardware elements for the ISS amateur radio station. These hardware elements have flown to ISS on three Shuttle flights and one Progress flight. The initial educational outreach system supports voice and packet (computer-to-computer radio link) capabilities. In addition, two Extra Vehicular Activities (EVAs) have been completed to install two antenna systems. These antenna systems were designed to be shared between the amateur radio equipment and a Russian EVA television system. These new antenna systems will ultimately enable a key facet of the amateur radio station to move into the Service Module living quarters, providing a more comfortable station set up for the ISS crew. In the future, ARISS hopes to fly a Slow Scan Television system on board the ISS as well as developing new systems for external mounting on the ISS. This paper will discuss the development, qualification, installation and operation of the ARISS amateur radio system. It will also discuss some of the challenges that the ARISS- international team of volunteers overcame to bring its first phase of equipment on ISS to fruition.

A Proper-Motion Corrected, Cross-Matched Catalog Of M Dwarfs In SDSS And FIRST

NASA Astrophysics Data System (ADS)

Arai, Erin; West, A. A.; Thyagarajan, N.; Agüeros, M.; Helfand, D.

2011-05-01

We present a preliminary analysis of M dwarfs identified in both the Sloan Digital Sky Survey (SDSS) and the Very Large Array's (VLA) Faint Images of the Radio Sky at Twenty-centimeters survey (FIRST). The presence of magnetic fields is often associated with indirect magnetic activity measurements, such as H-alpha or X-ray emission. Radio emission, in contrast, is directly proportional to the magnetic field strength in addition to being another measure of activity. We search for stellar radio emission by cross-matching the SDSS DR7 M dwarf sample with the FIRST catalog. The SDSS data allow us to examine the spectra of our objects and correlate the magnetic activity (H-alpha) with the magnetic field strength (radio emission). Accurate positions and proper motions are important for obtaining a complete list of overlapping targets. Positions in FIRST and SDSS need to be proper motion corrected in order to ensure unique target matches since nearby M dwarfs can have significant proper motions (up to 1'' per year). Some previous studies have neglected the significance of proper motions in identifying overlapping targets between SDSS and FIRST; we correct for some of these previous oversights. In addition the FIRST data were taken in multiple epochs; individual images need to be proper motion corrected before the images can be co-added. Our cross-match catalog puts important constraints on models of magnetic field generation in low-mass stars in addition to the true habitability of attending planets.

A Radio Astronomy Curriculum for the Middle School Classroom

NASA Astrophysics Data System (ADS)

Davis, J.; Finley, D. G.

2000-12-01

In the summer of 2000, two teachers working on a Masters of Science Teaching program at New Mexico Institute of Mining and Technology, spent eight weeks as interns at the Array Operations Center for the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, under the auspices of the National Science Foundation's (NSF) Research Experience for Teachers (RET) program. The resulting projects will directly benefit students in the indvidual classrooms, as well as provide an easy-to-access resource for other educators. One of the products is a Radio Astronomy Curriculum for upper middle school classes. Radio astronomy images, based on scientific research results using NRAO's Very Large Array, are featured on trading cards which include an explanation, a ``web challenge'', and in some cases, a comparison of radio and optical images. Each trading card has corresponding lesson plans with background information about the images and astronomy concepts needed to do the lessons. Comparison of optical and radio astronomy is used as much as possible to explain the information from research using visible and radio wavelengths. New Mexico's Content Standards and Benchmarks (developed using national standards) for science education was used as a guide for the activities. The three strands of science listed in the standards, Unifying Concepts and Processes, Science as Inquiry, and Science Content are addressed in the lessons. Higher level thinking and problem solving skills are featured throughout the curriculum. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. The NSF's RET program is gratefully acknowledged.

Compact radio sources in luminous infrared galaxies

NASA Astrophysics Data System (ADS)

Parra, Rodrigo

2007-08-01

Radio interferometry is an observational technique of high sensitivity and incomparably high spatial resolution. Moreover, because radio waves can freely propagate through interstellar dust and gas, it allows the study of regions of the universe completely obscured at other wavelengths. This thesis reports the observational and theoretical results of my research during the past four years which are mostly based on interferometric radio data. The COLA sample is an infrared selected sample of active star forming galaxies. We conducted 6 cm VLA and VLBI snapshot observations of the northern half of this sample. The radio emission seen at VLA scales is consistent with being powered by star formation activity because it follows the far infrared to radio correlation. We detect 22% of the sample sources in our VLBI snapshots. Based on luminosity arguments, we argue that these sub-parsec VLBI sources are powered by AGN activity. Furthermore, we find that VLBI detections are preferentially found in sources whose VLA scale structures have the highest peak brightnesses suggesting a strong correlation between compact starburst and AGN activity. This observational result is consistent with the theoretical picture of an Eddington-limited nuclear starburst acting as the last valve in the pipeline transporting the gas from kiloparsec scales onto the accretion disc of a buried AGN. Arp 220 is the archetypical ultra luminous infrared galaxy. For many years this source has been known to harbour a compact (~100 pc) cluster of unresolved 18 cm bright sources believed to be bright core collapse supernovae. Using multiwavelength VLBI observations, we obtained for the first time radio spectra for 18 of these sources. We find that over a half of them have spectra consistent with young supernovae. The rest can be better explained as older supernova remnants interacting with the high density starburst ISM. This finding allowed us to constrain the number of possible scenarios for the Arp 220 starburst. A subset of luminous infrared galaxies contain non-thermal spectral line emission from the OH radical. These OH megamasers often show diffuse extended (~100 pc) low gain emission surrounding compact ([Special characters omitted. 1 pc) high gain maser spots. These observational features have been explained in terms of unsaturated and saturated masers. Using numerical simulations we have shown how both the diffuse and compact components of the OH megamaser observed towards the luminous infrared galaxy IIIZw35 can be explained by a single phase of unsaturated maser clouds in which the compact bright masers are caused by the random line-of-sight overlap of several such clouds and the diffuse component by the beam spatial average of many low gain clouds too weak to be seen independently. The theoretical tools developed to analyse this particular case have been extended to the general problem of propagation of radiation in clumpy media.

Post-coma persons emerged from a minimally conscious state and showing multiple disabilities learn to manage a radio-listening activity.

PubMed

Lancioni, Giulio E; Singh, Nirbhay N; O'Reilly, Mark F; Sigafoos, Jeff; Colonna, Fabio; Buonocunto, Francesca; Sacco, Valentina; Megna, Marisa; Oliva, Doretta

2012-01-01

This study assessed microswitch-based technology to enable three post-coma adults, who had emerged from a minimally conscious state but presented motor and communication disabilities, to operate a radio device. The material involved a modified radio device, a microprocessor-based electronic control unit, a personal microswitch, and an amplified MP3 player. The study was carried out according to a non-concurrent multiple baseline design across participants. During the intervention, all three participants learned to operate the radio device, changing stations and tuning on some of them longer amounts of time than on others (i.e., suggesting preferences among the topics covered by those stations). They also ended a number of sessions before the maximum length of time allowed for them had elapsed. The practical (rehabilitation) implications of the findings were discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

New Antennas and Methods for the Low Frequency Stellar and Planetary Radio Astronomy

NASA Astrophysics Data System (ADS)

Konovalenko, A. A.; Falkovich, I. S.; Rucker, H. O.; Lecacheux, A.; Zarka, Ph.; Koliadin, V. L.; Zakharenko, V. V.; Stanislavsky, A. A.; Melnik, V. N.; Litvinenko, G. V.; Gridin, A. A.; Bubnov, I. N.; Kalinichenko, N. N.; Reznik, A. P.; Sidorchuk, M. A.; Stepkin, S. V.; Mukha, D. V.; Nikolajenko, V. S.; Karlsson, R.; Thide, B.

According to the special Program of the National Academy of Sciences of Ukraine, creation of the new giant Ukrainian radio telescope (GURT) was started a few years ago on the UTR-2 radio telescope observatory. The main goal is to reach maximum band at the lowest frequencies (10-70 MHz), effective area (step-by-step up to 100,000 sq.m), and high interference immunity for resolving many astrophysical tasks when the sensitivity is less limited by the confusion effects. These tasks include stellar radio astronomy (the Sun, solar wind, flare stars, pulsars, transients) and planetary one (Jupiter, planetary lightnings, Earth ionosphere, the Moon, exoplanets). This array should be complementary to the LOFAR, E-LOFAR systems. The first stages of the GURT (6 x 25 cross dipole active elements) and broad-band digital registration of the impulsive and sporadic events were tested in comparison with the existing largest decameter array UTR-2.

Space Weather Research in the Equatorial Region: A Philosophical Reinforcement

NASA Astrophysics Data System (ADS)

Chukwuma, Victor; Odunaike, Rasaki; Laoye, John

Investigations using radio waves reflected from the ionosphere, at high-and mid-latitudes indicate that ionospheric absorption can strongly increase following geomagnetic storms; which appears to suggest some definite relationship between ionospheric radio wave absorption and geomagnetic storms at these latitudes. However, corresponding earlier studies in the equatorial region did not appear to show any explicit relationship between ionospheric radio wave absorption and geomagnetic storm activity. This position appeared acceptable to the existing scientific paradigm, until in an act of paradigm shift, by a change of storm selection criteria, some more recent space weather investigations in the low latitudes showed that ionospheric radio wave absorption in the equatorial region clearly increases after intense storms. Given that these results in the equatorial region stood against the earlier results, this paper presently attempts to highlight their philosophical underpinning and posit that they constitute a scientific statement.

Discovery of a Fanaroff-Riley type 0 radio galaxy emitting at γ-ray energies

NASA Astrophysics Data System (ADS)

Grandi, Paola; Capetti, Alessandro; Baldi, Ranieri D.

2016-03-01

We present supporting evidence for the first association of a Fermi source, 3FGLJ1330.0-3818, Acero et al. (2015) with the Fanaroff-Riley type 0 (FR 0) radio galaxy Tol1326-379. FR 0s represent the majority of the local population of radio-loud active galactic nuclei but their nature is still unclear. They share the same nuclear and host properties as FR Is, but they show a large deficit of extended radio emission. Here we show that FR 0s can emit photons at very high energies. Tol1326-379 has a GeV luminosity of L>1 GeV ˜ 2 × 1042 erg s-1, typical of FR Is, but with a steeper γ-ray spectrum (Γ = 2.78 ± 0.14). This could be related to the intrinsic jet properties but also to a different viewing angle.

FRB as products of accretion disc funnels

NASA Astrophysics Data System (ADS)

Katz, J. I.

2017-10-01

The repeating FRB 121102, the only fast radio burst (FRB) with an accurately determined position, is associated with a variable persistent radio source. I suggest that an FRB originates in the accretion disc funnels of black holes. Narrowly collimated radiation is emitted along the wandering instantaneous angular momentum axis of accreted matter. This emission is observed as a fast radio burst when it sweeps across the direction to the observer. In this model, in contrast to neutron star (pulsar, RRAT or SGR) models, repeating FRBs do not have underlying periodicity and are co-located with persistent radio sources resulting from their off-axis emission. The model is analogous, on smaller spatial, lower mass and accretion rate and shorter temporal scales, to an active galactic nucleus (AGN), with FRB corresponding to blazars in which the jets point towards us. The small inferred black hole masses imply that FRBs are not associated with galactic nuclei.

Thunderstorms and ground-based radio noise as observed by radio astronomy Explorer 1

NASA Technical Reports Server (NTRS)

Caruso, J. A.; Herman, J. R.

1973-01-01

Radio Astronomy Explorer (RAE) data were analyzed to determine the frequency dependence of HF terrestrial radio noise power. RAE observations of individual thunderstorms, mid-ocean areas, and specific geographic regions for which concommitant ground based measurements are available indicate that noise power is a monotonically decreasing function of frequency which conforms to expectations over the geographic locations and time periods investigated. In all cases investigated, active thunderstorm regions emit slightly higher power as contrasted to RAE observations of the region during meteorologically quiet periods. Noise levels are some 15 db higher than predicted values over mid-ocean, while in locations where ground based measurements are available a maximum deviation of 5 db occurs. Worldwide contour mapping of the noise power at 6000 km for five individual months and four observing frequencies, examples of which are given, indicate high noise levels over continental land masses with corresponding lower levels over ocean regions.

Radio-loud AGN through the eyes of 3XMM, WISE and FIRST/NVSS

NASA Astrophysics Data System (ADS)

Mingo, B.

2014-07-01

We present the results from a new radio-loud AGN sample, obtained through the cross-correlation between the 3XMM, WISE and FIRST/NVSS catalogues. The radio selection allows us to eliminate the restrictions traditionally associated with mid-IR and X-ray sample selections, and to explore the population of lower luminosity AGN, in which the host galaxy contribution is substantial. We investigate the correlations between radio, mid-IR and X-ray emission associated to both stellar and AGN activity, and whether they can be disentangled. This work has been carried out as part of the ARCHES project. ARCHES (Astronomical Resource Cross-matching for High Energy Studies), funded within the EU/FP7-Cooperation Space framework, is a project which aims to produce well-characterised multi-wavelength data for large samples of sources drawn from the 3XMM serendipitous source catalogue.

Space Telecommunications Radio System Software Architecture Concepts and Analysis

NASA Technical Reports Server (NTRS)

Handler, Louis M.; Hall, Charles S.; Briones, Janette C.; Blaser, Tammy M.

2008-01-01

The Space Telecommunications Radio System (STRS) project investigated various Software Defined Radio (SDR) architectures for Space. An STRS architecture has been selected that separates the STRS operating environment from its various waveforms and also abstracts any specialized hardware to limit its effect on the operating environment. The design supports software evolution where new functionality is incorporated into the radio. Radio hardware functionality has been moving from hardware based ASICs into firmware and software based processors such as FPGAs, DSPs and General Purpose Processors (GPPs). Use cases capture the requirements of a system by describing how the system should interact with the users or other systems (the actors) to achieve a specific goal. The Unified Modeling Language (UML) is used to illustrate the Use Cases in a variety of ways. The Top Level Use Case diagram shows groupings of the use cases and how the actors are involved. The state diagrams depict the various states that a system or object may be in and the transitions between those states. The sequence diagrams show the main flow of activity as described in the use cases.

H{sub 2}O Megamasers toward Radio-bright Seyfert 2 Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, J. S.; Liu, Z. W.; Henkel, C.

2017-02-20

Using the Effelsberg-100 m telescope, we perform a successful pilot survey on H{sub 2}O maser emission toward a small sample of radio-bright Seyfert 2 galaxies with a redshift larger than 0.04. The targets were selected from a large Seyfert 2 sample derived from the spectroscopic Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). One source, SDSS J102802.9+104630.4 ( z ∼ 0.0448), was detected four times during our observations, with a typical maser flux density of ∼30 mJy and a corresponding (very large) luminosity of ∼1135 L {sub ⊙}. The successful detection of this radio-bright Seyfert 2 and an additional tentativemore » detection support our previous statistical results that H{sub 2}O megamasers tend to arise from Seyfert 2 galaxies with large radio luminosity. The finding provides further motivation for an upcoming larger H{sub 2}O megamaser survey toward Seyfert 2s with particularly radio-bright nuclei with the basic goal to improve our understanding of the nuclear environment of active megamaser host galaxies.« less

An XMM-Newton view of the radio galaxy 3C 411

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bostrom, Allison; Reynolds, Christopher S.; Tombesi, Francesco

We present the first high signal-to-noise XMM-Newton observations of the broad-line radio galaxy 3C 411. After fitting various spectral models, an absorbed double power-law (PL) continuum and a blurred relativistic disk reflection model (kdblur) are found to be equally plausible descriptions of the data. While the softer PL component (Γ = 2.11) of the double PL model is entirely consistent with that found in Seyfert galaxies (and hence likely originates from a disk corona), the additional PL component is very hard (Γ = 1.05); amongst the active galactic nucleus zoo, only flat-spectrum radio quasars (FSRQ) have such hard spectra. Togethermore » with the flat radio-spectrum displayed by this source, we suggest that it should instead be classified as an FSRQ. This leads to potential discrepancies regarding the jet inclination angle, with the radio morphology suggesting a large jet inclination but the FSRQ classification suggesting small inclinations. The kdblur model predicts an inner disk radius of at most 20 r {sub g} and relativistic reflection.« less

The LOFAR window on star-forming galaxies and AGNs - curved radio SEDs and IR-radio correlation at 0

NASA Astrophysics Data System (ADS)

Calistro Rivera, G.; Williams, W. L.; Hardcastle, M. J.; Duncan, K.; Röttgering, H. J. A.; Best, P. N.; Brüggen, M.; Chyży, K. T.; Conselice, C. J.; de Gasperin, F.; Engels, D.; Gürkan, G.; Intema, H. T.; Jarvis, M. J.; Mahony, E. K.; Miley, G. K.; Morabito, L. K.; Prandoni, I.; Sabater, J.; Smith, D. J. B.; Tasse, C.; van der Werf, P. P.; White, G. J.

2017-08-01

We present a study of the low-frequency radio properties of star-forming (SF) galaxies and active galactic nuclei (AGNs) up to redshift z = 2.5. The new spectral window probed by the Low Frequency Array (LOFAR) allows us to reconstruct the radio continuum emission from 150 MHz to 1.4 GHz to an unprecedented depth for a radio-selected sample of 1542 galaxies in ˜ 7 deg2 of the LOFAR Boötes field. Using the extensive multiwavelength data set available in Boötes and detailed modelling of the far-infrared to ultraviolet spectral energy distribution (SED), we are able to separate the star formation (N = 758) and the AGN (N = 784) dominated populations. We study the shape of the radio SEDs and their evolution across cosmic time and find significant differences in the spectral curvature between the SF galaxy and AGN populations. While the radio spectra of SF galaxies exhibit a weak but statistically significant flattening, AGN SEDs show a clear trend to become steeper towards lower frequencies. No evolution of the spectral curvature as a function of redshift is found for SF galaxies or AGNs. We investigate the redshift evolution of the infrared-radio correlation for SF galaxies and find that the ratio of total infrared to 1.4-GHz radio luminosities decreases with increasing redshift: q1.4 GHz = (2.45 ± 0.04) (1 + z)-0.15 ± 0.03. Similarly, q150 MHz shows a redshift evolution following q150 GHz = (1.72 ± 0.04) (1 + z)-0.22 ± 0.05. Calibration of the 150 MHz radio luminosity as a star formation rate tracer suggests that a single power-law extrapolation from q1.4 GHz is not an accurate approximation at all redshifts.

Close entrainment of massive molecular gas flows by radio bubbles in the central galaxy of Abell 1795

NASA Astrophysics Data System (ADS)

Russell, H. R.; McNamara, B. R.; Fabian, A. C.; Nulsen, P. E. J.; Combes, F.; Edge, A. C.; Hogan, M. T.; McDonald, M.; Salomé, P.; Tremblay, G.; Vantyghem, A. N.

2017-12-01

We present new ALMA observations tracing the morphology and velocity structure of the molecular gas in the central galaxy of the cluster Abell 1795. The molecular gas lies in two filaments that extend 5-7 kpc to the N and S from the nucleus and project exclusively around the outer edges of two inner radio bubbles. Radio jets launched by the central active galactic nucleus have inflated bubbles filled with relativistic plasma into the hot atmosphere surrounding the central galaxy. The N filament has a smoothly increasing velocity gradient along its length from the central galaxy's systemic velocity at the nucleus to -370 km s^{-1}, the average velocity of the surrounding galaxies, at the furthest extent. The S filament has a similarly smooth but shallower velocity gradient and appears to have partially collapsed in a burst of star formation. The close spatial association with the radio lobes, together with the ordered velocity gradients and narrow velocity dispersions, shows that the molecular filaments are gas flows entrained by the expanding radio bubbles. Assuming a Galactic XCO factor, the total molecular gas mass is 3.2 ± 0.2 × 109 M⊙. More than half lies above the N radio bubble. Lifting the molecular clouds appears to require an infeasibly efficient coupling between the molecular gas and the radio bubble. The energy required also exceeds the mechanical power of the N radio bubble by a factor of 2. Stimulated feedback, where the radio bubbles lift low-entropy X-ray gas that becomes thermally unstable and rapidly cools in situ, provides a plausible model. Multiple generations of radio bubbles are required to lift this substantial gas mass. The close morphological association then indicates that the cold gas either moulds the newly expanding bubbles or is itself pushed aside and shaped as they inflate.

Under the Radar: The First Woman in Radio Astronomy, Ruby Payne-Scott

NASA Astrophysics Data System (ADS)

Miller Goss, W.

2012-05-01

Under the Radar, the First Woman in Radio Astronomy, Ruby Payne-Scott W. Miller Goss, NRAO Socorro NM Ruby Payne-Scott (1912-1981) was an eminent Australian scientist who made major contributions to the WWII radar effort (CSIR) from 1941 to 1945. In late 1945, she pioneered radio astronomy efforts at Dover Heights in Sydney, Australia at a beautiful cliff top overlooking the Tasman Sea. Again at Dover Heights, Payne-Scott carried out the first interferometry in radio astronomy using an Australian Army radar antenna as a radio telescope at sun-rise, 26 January 1946. She continued these ground breaking activities until 1951. Ruby Payne-Scott played a major role in discovering and elucidating the properties of Type III bursts from the sun, the most common of the five classes of transient phenomena from the solar corona. These bursts are one of the most intensively studied forms of radio emission in all of astronomy. She is also one of the inventors of aperture synthesis in radio astronomy. I examine her career at the University of Sydney and her conflicts with the CSIR hierarchy concerning the rights of women in the work place, specifically equal wages and the lack of permanent status for married women. I also explore her membership in the Communist Party of Australia as well as her partially released Australian Scientific Intelligence Organization file. Payne-Scott’s role as a major participant in the flourishing radio astronomy research of the post war era remains a remarkable story. She had a number of strong collaborations with the pioneers of early radio astronomy in Australia: Pawsey, Mills, Christiansen, Bolton and Little. I am currently working on a popular version of the Payne-Scott story; “Making Waves, The Story of Ruby Payne-Scott: Australian Pioneer Radio Astronomer” will be published in 2013 by Springer in the Astronomers’ Universe Series.

[Correlations between functional activity of animal blood lymphocytes and change in solar activity].

PubMed

Karnaukhova, N A; Sergievich, L A

1999-01-01

It is shown that increase of Solar activity as measurement of the intensity of solar radio emissions at frequency of 2804 MHz leads to the reducing of the functional activity of immunocompetent cells in animal blood defining by parameter alpha.

Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. II. Observations of 3C 273 at minimum activity

NASA Astrophysics Data System (ADS)

Bruni, G.; Gómez, J. L.; Casadio, C.; Lobanov, A.; Kovalev, Y. Y.; Sokolovsky, K. V.; Lisakov, M. M.; Bach, U.; Marscher, A.; Jorstad, S.; Anderson, J. M.; Krichbaum, T. P.; Savolainen, T.; Vega-García, L.; Fuentes, A.; Zensus, J. A.; Alberdi, A.; Lee, S.-S.; Lu, R.-S.; Pérez-Torres, M.; Ros, E.

2017-08-01

Context. RadioAstron is a 10 m orbiting radio telescope mounted on the Spektr-R satellite, launched in 2011, performing Space Very Long Baseline Interferometry (SVLBI) observations supported by a global ground array of radio telescopes. With an apogee of 350 000 km, it is offering for the first time the possibility to perform μas-resolution imaging in the cm-band. Aims: The RadioAstron active galactic nuclei (AGN) polarization Key Science Project (KSP) aims at exploiting the unprecedented angular resolution provided by RadioAstron to study jet launching/collimation and magnetic-field configuration in AGN jets. The targets of our KSP are some of the most powerful blazars in the sky. Methods: We present observations at 22 GHz of 3C 273, performed in 2014, designed to reach a maximum baseline of approximately nine Earth diameters. Reaching an angular resolution of 0.3 mas, we study a particularly low-activity state of the source, and estimate the nuclear region brightness temperature, comparing with the extreme one detected one year before during the RadioAstron early science period. We also make use of the VLBA-BU-BLAZAR survey data, at 43 GHz, to study the kinematics of the jet in a 1.5-yr time window. Results: We find that the nuclear brightness temperature is two orders of magnitude lower than the exceptionally high value detected in 2013 with RadioAstron at the same frequency (1.4 × 1013 K, source-frame), and even one order of magnitude lower than the equipartition value. The kinematics analysis at 43 GHz shows that a new component was ejected 2 months after the 2013 epoch, visible also in our 22 GHz map presented here. Consequently this was located upstream of the core during the brightness temperature peak. Fermi-LAT observations for the period 2010-2014 do not show any γ-ray flare in conjunction with the passage of the new component by the core at 43 GHz. Conclusions: These observations confirm that the previously detected extreme brightness temperature in 3C 273, exceeding the inverse Compton limit, is a short-lived phenomenon caused by a temporary departure from equipartition. Thus, the availability of interferometric baselines capable of providing μas angular resolution does not systematically imply measured brightness temperatures over the known physical limits for astrophysical sources. The reduced image (FITS file) 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/604/A111

Fermi/LAT Observations of Swift/BAT Seyfert Galaxies: On the Contribution of Radio-Quiet Active Galactic Nuclei to the Extragalactic gamma-Ray Background

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Mushotzky, Richard F.; Sambruna, Rita M.; Davis, David S.; Reynolds, Christopher S.

2011-01-01

We present the analysis of 2.1 years of Fermi Large Area Telescope (LAT) data on 491 Seyfert galaxies detected by the Swift Burst Alert Telescope (BAT) survey. Only the two nearest objects, NGC 1068 and NGC 4945, which were identified in the Fermi first year catalog, are detected. Using Swift/BAT and radio 20 cm fluxes, we define a new radio-loudness parameter R(sub X,BAT) where radio-loud objects have logR(sub X,BAT) > -4.7. Based on this parameter, only radio-loud sources are detected by Fermi/LAT. An upper limit to the flux of the undetected sources is derived to be approx.2x10(exp -11) photons/sq cm/s, approximately seven times lower than the observed flux of NGC 1068. Assuming a median redshift of 0.031, this implies an upper limit to the gamma-ray (1-100 GeV) luminosity of < approx.3x10(exp 41) erg/s. In addition, we identified 120 new Fermi/LAT sources near the Swift/BAT Seyfert galaxies with significant Fermi/LAT detections. A majority of these objects do not have Swift/BAT counterparts, but their possible optical counterparts include blazars, flat-spectrum radio quasars, and quasars.

Discovery of Dramatic Optical Variability in SDSS J1100+4421: A Peculiar Radio-loud Narrow-line Seyfert 1 Galaxy?

NASA Astrophysics Data System (ADS)

Tanaka, Masaomi; Morokuma, Tomoki; Itoh, Ryosuke; Akitaya, Hiroshi; Tominaga, Nozomu; Saito, Yoshihiko; Stawarz, Łukasz; Tanaka, Yasuyuki T.; Gandhi, Poshak; Ali, Gamal; Aoki, Tsutomu; Contreras, Carlos; Doi, Mamoru; Essam, Ahmad; Hamed, Gamal; Hsiao, Eric Y.; Iwata, Ikuru; Kawabata, Koji S.; Kawai, Nobuyuki; Kikuchi, Yuki; Kobayashi, Naoto; Kuroda, Daisuke; Maehara, Hiroyuki; Matsumoto, Emiko; Mazzali, Paolo A.; Minezaki, Takeo; Mito, Hiroyuki; Miyata, Takashi; Miyazaki, Satoshi; Mori, Kensho; Moritani, Yuki; Morokuma-Matsui, Kana; Morrell, Nidia; Nagao, Tohru; Nakada, Yoshikazu; Nakata, Fumiaki; Noma, Chinami; Ohsuga, Ken; Okada, Norio; Phillips, Mark M.; Pian, Elena; Richmond, Michael W.; Sahu, Devendra; Sako, Shigeyuki; Sarugaku, Yuki; Shibata, Takumi; Soyano, Takao; Stritzinger, Maximilian D.; Tachibana, Yutaro; Taddia, Francesco; Takaki, Katsutoshi; Takey, Ali; Tarusawa, Ken'ichi; Ui, Takahiro; Ukita, Nobuharu; Urata, Yuji; Walker, Emma S.; Yoshii, Taketoshi

2014-10-01

We present our discovery of dramatic variability in SDSS J1100+4421 by the high-cadence transient survey Kiso Supernova Survey. The source brightened in the optical by at least a factor of three within about half a day. Spectroscopic observations suggest that this object is likely a narrow-line Seyfert 1 galaxy (NLS1) at z = 0.840, however, with unusually strong narrow emission lines. The estimated black hole mass of ~107 M ⊙ implies bolometric nuclear luminosity close to the Eddington limit. SDSS J1100+4421 is also extremely radio-loud, with a radio loudness parameter of R ~= 4 × 102-3 × 103, which implies the presence of relativistic jets. Rapid and large-amplitude optical variability of the target, reminiscent of that found in a few radio- and γ-ray-loud NLS1s, is therefore produced most likely in a blazar-like core. The 1.4 GHz radio image of the source shows an extended structure with a linear size of about 100 kpc. If SDSS J1100+4421 is a genuine NLS1, as suggested here, this radio structure would then be the largest ever discovered in this type of active galaxies.

Radio Monitoring of K2 Flare Star Wolf 359

NASA Astrophysics Data System (ADS)

Villadsen, Jacqueline; Wofford, Alia; Quintana, Elisa; Barclay, Thomas; Thackeray, Beverly

2018-01-01

Understanding M dwarf activity, including flares and eruptions, is important for characterizing exoplanet habitability. Active M dwarf Wolf 359, a well-known flare star, was in the Kepler K2 Campaign 14 field, with continuous high-cadence optical photometry throughout summer 2017. We have conducted a multi-wavelength observing campaign of this star to characterize the magnetic activity that would impact planets around such a star. I will present multi-band radio observations of this star, covering 250-500 MHz, 1-2 GHz, and 8-12 GHz, during a period with simultaneous optical photometry from K2. The higher frequency observations are sensitive to the population of non-thermal electrons in the stellar magnetosphere, and the low-frequency observations offer the potential to detect stellar ejecta.

Is WISEP J060738.65+242953.4 Really a Magnetically Active, Pole-on L Dwarf?

NASA Astrophysics Data System (ADS)

Route, Matthew

2017-07-01

The interplay of rotation and manifested magnetic activity on ultracool dwarfs (UCDs) is of key importance for gathering clues regarding the operation of the dynamos within these objects. A number of magnetized UCDs host kG-strength magnetic fields. It was recently reported that the L8 dwarf WISEP J060738.65+242953.4 is a radio-emitting UCD that is likely observed pole-on, due to its lack of photometric variability and narrow spectral lines. Follow-up radio observations at Arecibo Observatory, together with a careful analysis of previously published details, however, suggest that the scientific and statistical significance of the radio and spectroscopic data has been overstated. If the UCD is observed along its aligned spin/magnetic axis, the absence of observed Hα activity may present challenges to the auroral model of UCD magnetism, although short-term or long-term cyclic magnetic activity may explain this behavior. The Monte Carlo simulations presented here suggest that the source probably rotates with v \\sin I=6{--}12 km s-1, indicating that its inclination angle and rotational velocity are unexceptional and that its angular momentum has evolved as expected for brown dwarfs observed in ˜1 Myr old clusters. The discovery and verification of the most rapidly and slowest rotating brown dwarfs places valuable constraints on the angular momentum evolution and magnetic activity histories of these objects.

Astronaut William McArthur talks to students on earth using SAREX

NASA Technical Reports Server (NTRS)

1993-01-01

From the flight deck of the Earth-orbiting Space Shuttle Columbia, astronaut William S. McArthur talks to students on Earth. The mission specialist's activity was part of the Shuttle Amateur Radio Experiment (SAREX) which serves to enlighten students around the world on the topic of space travel. McArthur (call letters KC5ACR) is one of three licensed amateur radio operators on the seven-member flight.

Physics of the Geospace Response to Powerful HF Radio Waves

DTIC Science & Technology

2012-10-31

studies of the response of the Earth’s space plasma to high-power HF radio waves from the High-frequency Active Auroral Research Program ( HAARP ...of HF heating and explored to simulate artificial ducts. DMSP- HAARP experiments revealed that HF-created ion outflows and artificial density ducts...in the topside ionosphere appeared faster than predicted by the models, pointing to kinetic (suprathermal) effects. CHAMP/GRACE- HAARP experiments

Jugando en el Pidi: Active Learning, Early Child Development and Interactive Radio Instruction. Supporting Caregivers, Parents, and Young Children. LearnTech Case Study Series, No. 4.

ERIC Educational Resources Information Center

Bosch, Andrea; Crespo, Cecilia

In 1993, Bolivia was selected as a site to pilot an interactive radio instruction (IRI) project that would provide practical support to adult caregivers and children around early childhood development. Through linkages with health and education networks, PIDI (Programa Integral de Desarrollo Infantil) provided young children under the age of six…

The Brazilian Military: Its Role in Counter-Drug Activities

DTIC Science & Technology

1992-06-01

34Police Uncover ’New’ Medellin Cartel Drug Route," Brasilia Radio Nacional de Amazonia , in Portuguese, 29 November 1989, translated in FBIS, 30...42 "Destruction of Clandestine Airstrips to Begin," Brasi Radio Nacional de Amazonia Network, in Portuguese, 2 May 1990, translated in FBIS, 3 May... de Ciencia Politica e Relacoes Internacionais (REL) Universidade de Brasilia 70.910 Brasilia, D.F. BRAZIL 107

Radio-protective effect of cinnamic acid, a phenolic phytochemical, on genomic instability induced by X-rays in human blood lymphocytes in vitro.

PubMed

Cinkilic, Nilufer; Tüzün, Ece; Çetintaş, Sibel Kahraman; Vatan, Özgür; Yılmaz, Dilek; Çavaş, Tolga; Tunç, Sema; Özkan, Lütfi; Bilaloğlu, Rahmi

2014-08-01

The present study was designed to determine the protective activity of cinnamic acid against induction by X-rays of genomic instability in normal human blood lymphocytes. This radio-protective activity was assessed by use of the cytokinesis-block micronucleus test and the alkaline comet assay, with human blood lymphocytes isolated from two healthy donors. A Siemens Mevatron MD2 (Siemens AG, USA, 1994) linear accelerator was used for the irradiation with 1 or 2 Gy. Treatment of the lymphocytes with cinnamic acid prior to irradiation reduced the number of micronuclei when compared with that in control samples. Treatment with cinnamic acid without irradiation did not increase the number of micronuclei and did not show a cytostatic effect in the lymphocytes. The results of the alkaline comet assay revealed that cinnamic acid reduces the DNA damage induced by X-rays, showing a significant radio-protective effect. Cinnamic acid decreased the frequency of irradiation-induced micronuclei by 16-55% and reduced DNA breakage by 17-50%, as determined by the alkaline comet assay. Cinnamic acid may thus act as a radio-protective compound, and future studies may focus on elucidating the mechanism by which cinnamic acid offers radioprotection. Copyright © 2014 Elsevier B.V. All rights reserved.

Multiwavelength and parsec-scale properties of extragalactic jets. Doctoral Thesis Award Lecture 2015

NASA Astrophysics Data System (ADS)

Müller, C.

2016-07-01

Extragalactic jets originating from the central supermassive black holes of active galaxies are powerful, highly relativistic plasma outflows, emitting light from the radio up to the γ-ray regime. The details of their formation, composition and emission mechanisms are still not completely clear. The combination of high-resolution observations using very long baseline interferometry (VLBI) and multiwavelength monitoring provides the best insight into these objects. Here, such a combined study of sources of the TANAMI sample is presented, investigating the parsec-scale and high-energy properties. The TANAMI program is a multiwavelength monitoring program of a sample of the radio and γ-ray brightest extragalactic jets in the southern sky, below -30o declination. We obtain the first-ever VLBI images for most of the sources, providing crucial information on the jet kinematics and brightness distribution at milliarcsecond resolution. Two particular sources are discussed in detail: PMN J1603-4904 , which can be classified either as an atypical blazar or a γ-ray loud (young) radio galaxy, and Centaurus A, the nearest radio-loud active galaxy. The VLBI kinematics of the innermost parsec of Centaurus A's jet result in a consistent picture of an accelerated jet flow with a spine-sheath like structure.

Radio and Optical Telescopes for School Students and Professional Astronomers

NASA Astrophysics Data System (ADS)

Hosmer, Laura; Langston, G.; Heatherly, S.; Towner, A. P.; Ford, J.; Simon, R. S.; White, S.; O'Neil, K. L.; Haipslip, J.; Reichart, D.

2013-01-01

The NRAO 20m telescope is now on-line as a part of UNC's Skynet worldwide telescope network. The NRAO is completing integration of radio astronomy tools with the Skynet web interface. We present the web interface and astronomy projects that allow students and astronomers from all over the country to become Radio Astronomers. The 20 meter radio telescope at NRAO in Green Bank, WV is dedicated to public education and also is part of an experiment in public funding for astronomy. The telescope has a fantastic new web-based interface, with priority queuing, accommodating priority for paying customers and enabling free use of otherwise unused time. This revival included many software and hardware improvements including automatic calibration and improved time integration resulting in improved data processing, and a new ultra high resolution spectrometer. This new spectrometer is optimized for very narrow spectral lines, which will allow astronomers to study complex molecules and very cold regions of space in remarkable detail. In accordance with focusing on broader impacts, many public outreach and high school education activities have been completed with many confirmed future activities. The 20 meter is now a fully automated, powerful tool capable of professional grade results available to anyone in the world. Drop by our poster and try out real-time telescope control!

ULF radio monitoring network in a seismic area

NASA Astrophysics Data System (ADS)

Toader, Victorin; Moldovan, Iren-Adelina; Ionescu, Constantin; Marmureanu, Alexandru

2017-04-01

ULF monitoring is a part of a multidisciplinary network (AeroSolSys) located in Vrancea (Curvature Carpathian Mountains). Four radio receivers (100 kHz - microwave) placed on faults in a high seismic area characterized by deep earthquakes detect fairly weak radio waves. The radio power is recorded in correlation with many other parameters related to near surface low atmosphere phenomena (seismicity, solar radiation, air ionization, electromagnetic activity, radon, CO2 concentration, atmospheric pressure, telluric currents, infrasound, seismo-acoustic emission, meteorological information). We follow variations in the earth's surface propagate radio waves avoiding reflection on ionosphere. For this reason the distance between stations is less than 60 km and the main source of emission is near (Bod broadcasting transmitter for long- and medium-wave radio, next to Brasov city). In the same time tectonic stress affects the radio propagation in air and it could generates ULF waves in ground (LAI coupling). To reduce the uncertainty is necessary to monitor a location for extended periods of time to outline local and seasonal fluctuations. Solar flares do not affect seismic activity but they produce disturbances in telecommunications networks and power grids. Our ULF monitoring correlated with two local magnetometers does not indicate this so far with our receivers. Our analysis was made during magnetic storms with Kp 7 and 8 according to NOAA satellites. To correlate the results we implemented an application that monitors the satellite EUTELSAT latency compared to WiMAX land communication in the same place. ULF band radio monitoring showed that our receiver is dependent on temperature and that it is necessary to introduce a band pass filter in data analysis. ULF data acquisition is performed by Kinemetrics and National Instruments digitizers with a sampling rate of 100 Hz in Miniseed format and then converted into text files with 1 Hz rate for analysis in very low frequency. In both cases we use spectrum analysis in three bands of frequency with different filters. More results showed that tectonic stress generated by seismicity is more important than effects of solar flares. This work was partially supported by the Partnership in Priority Areas Program - PNII, under MEN-UEFISCDI, DARING Project no. 69/2014 and the Nucleu Program - PN 16-35, Project no. 03 01.

The X-ray view of radio-loud active galactic nuclei: The central engine and its environment

NASA Astrophysics Data System (ADS)

Donato, Davide

The non-thermal emission from many Active Galactic Nuclei (AGN) is obscured by optically thick circumnuclear matter, particularly at optical and ultraviolet wavelengths. In radio-loud (RL) sources, the AGN activity is coupled with the presence of a bipolar jet that emit radio through g-ray light which is relativistically beamed along the jet axes. The combination of absorption and beaming produces highly anisotropic radiation. The understanding of the origin and magnitude of this radiation allows astronomers to unify different classes of AGN; that is, to identify each single, underlying AGN type that gives rise to different classes through different orientations with respect to the jet axis. This is the fundamental notion behind what are called "unification models" of AGN. Although this general idea is well accepted, many aspects remain matter of debate. In fact, the explanation of the wide and complex variety of AGN phenomena must be searched in a combination of apparent differences (like orientation) and real differences in a number of physical parameters (like gas/dust content and distribution, luminosity, etc.). The goal of this thesis is to address some of the RL unification open questions using X-ray data. The improved sensitivity and angular resolution of a new generation of satellites, combined with the fact that X-rays provide useful information on a variety of AGN phenomena, will allow me to: (1) Study the broadband X-ray continua of BL Lacertae objects (BL Lacs) and Flat Spectrum Radio Quasars (FSRQs); (2) Probe the emission from the very inner region of an AGN; (3) Determine the presence and characteristic of extended X-ray emission from the AGN environment. The results obtained from theses studies will provide me insights into (1) the X-ray average spectral properties of BL Lacs and FSRQs and the physical processes responsible of the emission; (2) the presence of the obscuring torus and the amount of absorption, (3) the nature of X-ray emission, and (4) the type of accretion and efficiency of the accretion process in Fanaroff-Riley I radio galaxies; (5) the properties of the gas in BL Lacs and (6) its effects on the AGN activity and jet properties.

Homologous Flare-CME Events and Their Metric Type II Radio Burst Association

NASA Technical Reports Server (NTRS)

Yashiro, S.; Gopalswamy, N.; Makela, P.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.; Mahalakshmi, K.;

Determination of the System Mass and the Individual Masses of the Pluto System from New Horizons Radio Tracking

NASA Astrophysics Data System (ADS)

Hahn, Matthias; Pätzold, Martin; Andert, Tom; Bird, Michael K.; Tyler, Leonard G.; Linscott, Ivan; Hinson, Dave P.; Stern, Alan; Weaver, Hal; Olkin, Cathrin; Young, Leslie; Ennico, Kimberly

2015-11-01

One objective of the New Horizons Radio Science Experiment REX is the determination of the system mass and the individual masses of Pluto and Charon. About four weeks of two-way radio tracking centered around the closest approach of New Horizons to the Pluto system were processed. Major problems during the processing were caused by the small net forces of the spacecraft thruster activity, which produce extra Δv on the spacecraft motion superposed onto the continuously perturbed motion caused by the attracting forces of the Pluto system. The times of spacecraft thruster activity are known but the applied Δv needs to be specifically adjusted. No two-way tracking was available for the day of the flyby, but slots of REX one-way uplink tracking are used to cover the most important times near closest approach, e.g. during occultation entries and exits. This will help to separate the individual masses of Pluto and Charon from the system mass.

Monsters and babies from the first/IRAS survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Bruegel, W J M

Radio continuum emission at cm wavelengths is relatively little affected by extinction. When combined with far-infrared (FIR) surveys this provides for a convenient and unbiased method to select (radio-loud) AGN and starbursts deeply embedded in gas and dust-rich galaxies. Such radio-selected FIR samples are useful for detailed investigations of the complex relationships between (radio) galaxy and starburst activity, and to determine whether ULIRGs are powered by hidden quasars (monsters) or young stars (babies). We present the results of a large program to obtain identifications and spectra of radio-sleected, optically faint IRAS/FSC objects using the FIRST/VLA 20 cm survey (Becker, Whitemore » and Helfand 1995). These objects are all radio-'quiet' in the sense that their radio power/FIR luminosities follow the well-known radio/FIR relationship for star forming galaxies. We compare these results to a previous study by our group of a sample of radio-'loud' IRAS/FSC ULIRGs selected from the Texas 365 MHz survey (Douglas et al. 1996). Many of these objects also show evidence for dominant, A-type stellar populations, as well as high ionization lines usually associated with AGN. These radio-loud ULIRGs have properties intermediate between those of starbursts and quasars, suggesting a possibile evolutionary connection. Deep Keck spectroscopic observations of three ULIRGs from these samples are presented, including high signal-to-noise spectropolarimetry. The polarimetry observations failed to show evidence of a hidden quasar in polarized (scattered) light in the two systems in which the stellar light was dominated by A-type stars. Although observations of a larger sample would be needed to allow a general conclusion, our current data suggest that a large fraction of ULIRGs may be powered by luminous starbursts, not by hidden, luminous AGN (quasars). While we used radio-selected FIR sources to search for evidence of a causal AGN/starburst connection, we conclude our presentation with a dramatic example of an AGN/starburst object from an entirely unrelated quasar survey selected at the opposite, blue end of the spectrum.« less

The mystery of the "Kite" radio source in Abell 2626: Insights from new Chandra observations

NASA Astrophysics Data System (ADS)

Ignesti, A.; Gitti, M.; Brunetti, G.; O'Sullivan, E.; Sarazin, C.; Wong, K.

2018-03-01

Context. We present the results of a new Chandra study of the galaxy cluster Abell 2626. The radio emission of the cluster shows a complex system of four symmetric arcs without known correlations with the thermal X-ray emission. The mirror symmetry of the radio arcs toward the center and the presence of two optical cores in the central galaxy suggested that they may be created by pairs of precessing radio jets powered by dual active galactic nuclei (AGNs) inside the core dominant galaxy. However, previous observations failed to observe the second jetted AGN and the spectral trend due to radiative age along the radio arcs, thus challenging this interpretation. Aim. The new Chandra observation had several scientific objectives, including the search for the second AGN that would support the jet precession model. We focus here on the detailed study of the local properties of the thermal and non-thermal emission in the proximity of the radio arcs, in order to obtain further insights into their origin. Methods: We performed a standard data reduction of the Chandra dataset deriving the radial profiles of temperature, density, pressure and cooling time of the intra-cluster medium. We further analyzed the two-dimensional (2D) distribution of the gas temperature, discovering that the south-western junction of the radio arcs surrounds the cool core of the cluster. Results: We studied the X-ray surface brightness and spectral profiles across the junction, finding a cold front spatially coincident with the radio arcs. This may suggest a connection between the sloshing of the thermal gas and the nature of the radio filaments, raising new scenarios for their origin. A tantalizing possibility is that the radio arcs trace the projection of a complex surface connecting the sites where electrons are most efficiently reaccelerated by the turbulence that is generated by the gas sloshing. In this case, diffuse emission embedded by the arcs and with extremely steep spectrum should be most visible at very low radio frequencies.

Solar and stellar coronal plasmas

NASA Technical Reports Server (NTRS)

Golub, Leon

1989-01-01

Progress in observational, theoretical, and radio studies of coronal plasmas is summarized. Specifically work completed in the area of solar and stellar magnetic fields, related photospheric phenomena and the relationships between magnetism, rotation, coronal and chromospheric emission in solar-like stars is described. Also outlined are theoretical studies carried out in the following areas, among others: (1) neutral beams as the dominant energy transport mechanism in two ribbon-flares; (2) magneto hydrodynamic and circuit models for filament eruptions; and (3) studies of radio emission mechanisms in transient events. Finally, radio observations designed for coronal activity studies of the sun and of solar-type coronae are described. A bibliography of publications and talks is provided along with reprints of selected articles.

Observations of the auroral hectometric radio emission onboard the INTERBALL-1 satellite

NASA Astrophysics Data System (ADS)

Kuril'Chik, V. N.

2007-06-01

The results of five-year (1995 2000) continuous observations of the auroral radio emission (ARE) in the hectometric wavelength range on the high-apogee INTERBALL-1 satellite are presented. Short intense bursts of the auroral hectometric radio emission (AHR) were observed at frequencies of 1463 and 1501 kHz. The bursts were observed predominantly at times when the terrestrial magnetosphere was undisturbed (in the quiet Sun period), and their number decreased rapidly with increasing solar activity. The bursts demonstrated seasonal dependence in the Northern and Southern hemispheres (dominating in the autumn-winter period). Their appearance probably depends on the observation time (UT). A qualitative explanation of the AHR peculiarities is given.

Surface Penetrating Radar Simulations for Europa

NASA Technical Reports Server (NTRS)

Markus, T.; Gogineni, S. P.; Green, J. L.; Fung, S. F.; Cooper, J. F.; Taylor, W. W. L.; Garcia, L.; Reinisch, B. W.; Song, P.; Benson, R. F.

2004-01-01

The space environment above the icy surface of Europa is a source of radio noise in this frequency range from natural sources in the Jovian magnetosphere. The ionospheric and magnetospheric plasma environment of Europa affects propagation of transmitted and return signals between the spacecraft and the solid surface in a frequency-dependent manner. The ultimate resolution of the subsurface sounding measurements will be determined, in part, by a capability to mitigate these effects. We discuss an integrated multi-frequency approach to active radio sounding of the Europa ionospheric and local magnetospheric environments, based on operational experience from the Radio Plasma Imaging @PI) experiment on the IMAGE spacecraft in Earth orbit, in support of the subsurface measurement objectives.

A World-Wide Net of Solar Radio Spectrometers: e-CALLISTO

NASA Astrophysics Data System (ADS)

Benz, A. O.; Monstein, C.; Meyer, H.; Manoharan, P. K.; Ramesh, R.; Altyntsev, A.; Lara, A.; Paez, J.; Cho, K.-S.

2009-04-01

Radio spectrometers of the CALLISTO type to observe solar flares have been distributed to nine locations around the globe. The instruments observe automatically, their data is collected every day via internet and stored in a central data base. A public web-interface exists through which data can be browsed and retrieved. The nine instruments form a network called e-CALLISTO. It is still growing in the number of stations, as redundancy is desirable for full 24 h coverage of the solar radio emission in the meter and low decimeter band. The e-CALLISTO system has already proven to be a valuable new tool for monitoring solar activity and for space weather research.

Design and Implementation of an Underlay Control Channel for Cognitive Radios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daryl Wasden; Hussein Moradi; Behrouz Farhang-Boroujeny

Implementation of any cognitive radio network requires an effective control channel that can operate under various modes of activity from the primary users. This paper reports the design and implementation of a filter bank multicarrier spread spectrum (FBMC-SS) system for use as the control channel in cognitive radio networks. The proposed design is based on a filtered multitone (FMT) implementation. Carrier and timing acquisition and tracking methods as well as a blind channel estimation method are developed for the proposed control channel. We also report an implementation of the proposed FBMC-SS system on a hardware platform; a FlexRIO FPGA modulemore » from National Instruments.« less

Blind detection of giant pulses: GPU implementation

NASA Astrophysics Data System (ADS)

Ait-Allal, Dalal; Weber, Rodolphe; Dumez-Viou, Cédric; Cognard, Ismael; Theureau, Gilles

2012-01-01

Radio astronomical pulsar observations require specific instrumentation and dedicated signal processing to cope with the dispersion caused by the interstellar medium. Moreover, the quality of observations can be limited by radio frequency interference (RFI) generated by Telecommunications activity. This article presents the innovative pulsar instrumentation based on graphical processing units (GPU) which has been designed at the Nançay Radio Astronomical Observatory. In addition, for giant pulsar search, we propose a new approach which combines a hardware-efficient search method and some RFI mitigation capabilities. Although this approach is less sensitive than the classical approach, its advantage is that no a priori information on the pulsar parameters is required. The validation of a GPU implementation is under way.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1990-01-01

Archival reports are given on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA), including space communications, radio navigation, radio science, ground-based radio and radar astronomy, and the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, supporting research and technology, implementation, and operations. Also included is TDA-funded activity at JPL on data and information systems and reimbursable DSN work performed for other space agencies through NASA. In the search for extraterrestrial intelligence (SETI), implementation and operations for searching the microwave spectrum are reported. Use of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets are discussed.

RAiSE II: resolved spectral evolution in radio AGN

NASA Astrophysics Data System (ADS)

Turner, Ross J.; Rogers, Jonathan G.; Shabala, Stanislav S.; Krause, Martin G. H.

2018-01-01

The active galactic nuclei (AGN) lobe radio luminosities modelled in hydrodynamical simulations and most analytical models do not address the redistribution of the electron energies due to adiabatic expansion, synchrotron radiation and inverse-Compton scattering of cosmic microwave background photons. We present a synchrotron emissivity model for resolved sources that includes a full treatment of the loss mechanisms spatially across the lobe, and apply it to a dynamical radio source model with known pressure and volume expansion rates. The bulk flow and dispersion of discrete electron packets is represented by tracer fields in hydrodynamical simulations; we show that the mixing of different aged electrons strongly affects the spectrum at each point of the radio map in high-powered Fanaroff & Riley type II (FR-II) sources. The inclusion of this mixing leads to a factor of a few discrepancy between the spectral age measured using impulsive injection models (e.g. JP model) and the dynamical age. The observable properties of radio sources are predicted to be strongly frequency dependent: FR-II lobes are expected to appear more elongated at higher frequencies, while jetted FR-I sources appear less extended. The emerging FR0 class of radio sources, comprising gigahertz peaked and compact steep spectrum sources, can potentially be explained by a population of low-powered FR-Is. The extended emission from such sources is shown to be undetectable for objects within a few orders of magnitude of the survey detection limit and to not contribute to the curvature of the radio spectral energy distribution.

Radio-interferometric Monitoring of FRB 131104: A Coincident AGN Flare, but No Evidence for a Cosmic Fireball

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shannon, R. M.; Ravi, V., E-mail: ryan.shannon@csiro.au, E-mail: vikram@caltech.edu

2017-03-10

The localization of fast radio bursts (FRBs) has been hindered by the poor angular resolution of the detection observations and inconclusive identification of transient or variable counterparts. Recently a γ -ray pulse of 380 s duration has been associated with FRB 131104. We report on radio-continuum imaging observations of the original localization region of the FRB, beginning three days after the event and comprising 25 epochs over 2.5 years. We argue that the probability of an association between the FRB and the γ -ray transient has been overestimated. We provide upper limits on radio afterglow emission that would be predictedmore » if the γ -ray transient was associated with an energetic γ -ray burst. We further report the discovery of an unusual variable radio source spatially and temporally coincident with FRB 131104, but not spatially coincident with the γ -ray event. The radio variable flares by a factor of 3 above its long-term average within 10 day of the FRB at 7.5 GHz, with a factor-of-2 increase at 5.5 GHz. Since the flare, the variable has persisted with only modest modulation and never approached the flux density observed in the days after the FRB. We identify an optical counterpart to the variable. Optical and infrared photometry, and deep optical spectroscopy, suggest that the object is a narrow-line radio active galactic nucleus.« less

The jet/wind outflow in Centaurus A: a local laboratory for AGN feedback

NASA Astrophysics Data System (ADS)

McKinley, B.; Tingay, S. J.; Carretti, E.; Ellis, S.; Bland-Hawthorn, J.; Morganti, R.; Line, J.; McDonald, M.; Veilleux, S.; Wahl Olsen, R.; Sidonio, M.; Ekers, R.; Offringa, A. R.; Procopio, P.; Pindor, B.; Wayth, R. B.; Hurley-Walker, N.; Bernardi, G.; Gaensler, B. M.; Haverkorn, M.; Kesteven, M.; Poppi, S.; Staveley-Smith, L.

2018-03-01

We present new radio and optical images of the nearest radio galaxy Centaurus A and its host galaxy NGC 5128. We focus our investigation on the northern transition region, where energy is transported from the ˜5 kpc (˜5 arcmin) scales of the northern inner lobe (NIL) to the ˜30 kpc (˜30 arcmin) scales of the northern middle lobe (NML). Our Murchison Widefield Array observations at 154 MHz and our Parkes radio telescope observations at 2.3 GHz show diffuse radio emission connecting the NIL to the NML, in agreement with previous Australia Telescope Compact Array observations at 1.4 GHz. Comparison of these radio data with our wide-field optical emission-line images show the relationship between the NML radio emission and the ionized filaments that extend north from the NIL, and reveal a new ionized filament to the east, possibly associated with a galactic wind. Our deep optical images show clear evidence for a bipolar outflow from the central galaxy extending to intermediate scales, despite the non-detection of a southern radio counterpart to the NML. Thus, our observational overview of Centaurus A reveals a number of features proposed to be associated with active galactic nucleus feedback mechanisms, often cited as likely to have significant effects in galaxy evolution models. As one of the closest galaxies to us, Centaurus A therefore provides a unique laboratory to examine feedback mechanisms in detail.