SUZAKU X-RAY FOLLOW-UP OBSERVATIONS OF SEVEN UNASSOCIATED FERMI-LAT GAMMA-RAY SOURCES AT HIGH GALACTIC LATITUDES

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

Takahashi, Y.; Kataoka, J.; Nakamori, T.

2012-03-01

We report on our second-year campaign of X-ray follow-up observations of unidentified Fermi Large Area Telescope (LAT) {gamma}-ray sources at high Galactic latitudes (|b| > 10 Degree-Sign ) using the X-ray Imaging Spectrometer on board the Suzaku X-ray Observatory. In this second year of the project, seven new targets were selected from the First Fermi-LAT Catalog, and studied with 20-40 ks effective Suzaku exposures. We detected an X-ray point source coincident with the position of the recently discovered millisecond pulsar (MSP) PSR J2302+4442 within the 95% confidence error circle of 1FGL J2302.8+4443. The X-ray spectrum of the detected counterpart wasmore » well fit by a blackbody model with temperature of kT {approx_equal} 0.3 keV, consistent with an origin of the observed X-ray photons from the surface of a rotating magnetized neutron star. For four other targets that were also recently identified with a normal pulsar (1FGL J0106.7+4853) and MSPs (1FGL J1312.6+0048, J1902.0-5110, and J2043.2+1709), only upper limits in the 0.5-10 keV band were obtained at the flux levels of {approx_equal} 10{sup -14} erg cm{sup -2} s{sup -1}. A weak X-ray source was found in the field of 1FGL J1739.4+8717, but its association with the variable {gamma}-ray emitter could not be confirmed with the available Suzaku data alone. For the remaining Fermi-LAT object 1FGL J1743.8-7620 no X-ray source was detected within the LAT 95% error ellipse. We briefly discuss the general properties of the observed high Galactic-latitude Fermi-LAT objects by comparing their multiwavelength properties with those of known blazars and MSPs.« less

Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth A.

2010-01-01

Topics include: Fermi LAT Collaboration groups; galactic results from LAT; a GeV, wide-field instrument; the 1FGL catalog, the Fermi LAT 1FGL source catalog, unidentified gamma-ray sources; variability in 1FGL sources; curvature in 1FGL sources; spectral-variability classification; gamma-ray pulsars and MSPs; GeV PWN - where to look; Crab pulsar and nebula; Vela X nebular of Vela pulsar; MSH 15-52; GeV PWNe spectra; GeV nebula limits; Nebula search of LAT pulsars; supernova remnants; SNR: GeV morphology; SNR: molecular connection; SNR: GeV breaks; SNR: young vs. old. The summary includes slides about the Large Area Telescope (LAT) and LAT sensitivity with time.

Revisiting the Gamma-Ray Source 2FGL J1823.8+4312

NASA Astrophysics Data System (ADS)

Stern, Daniel; Assef, Roberto J.

2013-02-01

One of the great challenges of gamma-ray astronomy is identifying the lower energy counterparts to these high-energy sources. Recently, in this journal, Massaro et al. attempted to find the counterpart of 2FGL J1823.8+4312, a gamma-ray active galactic nucleus (AGN) of uncertain type from the Second Fermi Large Area Telescope catalog. After considering mid-infrared data in the field from the Wide-field Infrared Survey Explorer (WISE), those authors conclude that the preferred identification of 2FGL J1823.8+4312 is WISE J182352.33+431452.5, despite the fact that the mid-infrared source is undetected at radio energies. They claim that WISE J182352.33+431452.5 constitutes the discovery of a new class of extragalactic X-ray source, either a radio-faint blazar or the prototype of a new class of active galaxy with an enigmatic spectral energy distribution. This conclusion is claimed to be independent of whether or not the WISE source is the actual counterpart to 2FGL J1823.8+4312. Based on a re-analysis of public data in this field and new spectroscopy from Palomar, we conclude that WISE J182352.33+431452.5 is a dust-reddened quasar at z = 0.560, a representative example of a very common extragalactic AGN class. Were WISE J182352.33+431452.5 to be associated with the gamma-ray emission, this would be an unusual and exciting discovery. However, we argue that 2FGL J1823.8+4312 is more likely associated with either WISE J182409.25+431404.7 or, more likely, WISE J182419.04+430949.6, two radio-loud sources in the field. The former is a radio-loud quasar and the latter is an optically variable source with a featureless blue spectrum.

The Fermi Large Area Telescope Thrid Gamma-ray Source Catalog

NASA Astrophysics Data System (ADS)

Stephens, Thomas E.; Ballet, Jean; Burnett, Toby; Cavazzuti, Elisabetta; Digel, Seth William; Fermi LAT Collaboration

2015-01-01

We present an overview of the third Fermi Large Area Telescope source catalog (3FGL) of sources in the 100 MeV - 300 GeV range. Based on the first four years of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the 2FGL catalog (Nolan et al. 2012, ApJS 199, 31), the 3FGL catalog incorporates twice as much data as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse gamma-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources, with source location regions, spectral properties, and monthly light curves for each. For approximately one-third of the sources we have not found counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate the contribution of unresolved sources to the Galactic diffuse emission.

2FGL J1311.7-3429 JOINS THE BLACK WIDOW CLUB

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

Romani, Roger W.

2012-08-01

We have found an optical/X-ray counterpart candidate for the bright, but presently unidentified, Fermi source 2FGL J1311.7-3429. This counterpart undergoes large-amplitude quasi-sinusoidal optical modulation with a 1.56 hr (5626 s) period. The modulated flux is blue at peak, with T{sub eff} Almost-Equal-To 14, 000 K, and redder at minimum. Superimposed on this variation are dramatic optical flares. Archival X-ray data suggest modest binary modulation, but no eclipse. With the {gamma}-ray properties, this appears to be another black-widow-type millisecond pulsar. If confirmation pulses can be found in the GeV data, this binary will have the shortest orbital period of any knownmore » spin-powered pulsar. The flares may be magnetic events on the rapidly rotating companion or shocks in the companion-stripping wind. While this may be a radio-quiet millisecond pulsar, we show that such objects are a small subset of the {gamma}-ray pulsar population.« less

1FGL J1417.7-4407: A Likely Gamma-Ray Bright Binary with A Massive Neutron Star and A Giant Secondary

NASA Technical Reports Server (NTRS)

Strader, Jay; Chomiuk, Laura; Cheung, C. C.; Sand, David J.; Donato, Davide; Corbet, Robin H. D.; Koeppe, Dana; Edwards, Philip G.; Stevens, Jamie; Petrov, Leonid

2015-01-01

We present multiwavelength observations of the persistent Fermi-Large Area Telescope unidentified gamma-ray source 1FGL J1417.7-4407, showing it is likely to be associated with a newly discovered X-ray binary containing a massive neutron star (nearly 2 solar mass) and a approximately 0.35 solar mass giant secondary with a 5.4 day period. SOAR optical spectroscopy at a range of orbital phases reveals variable double-peaked H alpha emission, consistent with the presence of an accretion disk. The lack of radio emission and evidence for a disk suggests the gamma-ray emission is unlikely to originate in a pulsar magnetosphere, but could instead be associated with a pulsar wind, relativistic jet, or could be due to synchrotron self-Compton at the disk-magnetosphere boundary. Assuming a wind or jet, the high ratio of gamma- ray to X-ray luminosity (approximately 20) suggests efficient production of gamma-rays, perhaps due to the giant companion. The system appears to be a low-mass X-ray binary that has not yet completed the pulsar recycling process. This system is a good candidate to monitor for a future transition between accretion-powered and rotational-powered states, but in the context of a giant secondary.

VizieR Online Data Catalog: Radio follow-up on 3FGL unassociated sources (Schinzel+, 2017)

NASA Astrophysics Data System (ADS)

Schinzel, F. K.; Petrov, L.; Taylor, G. B.; Edwards, P. G.

2017-11-01

The 3FGL catalog covers the entire sky, thus we performed follow-up observations at two radio interferometric arrays: The Australia Telescope Compact Array (ATCA) in the Southern Hemisphere for observing sources with declinations in the range [-90,+10] and the Jansky Very Large Array (VLA) in the Northern Hemisphere for observing sources with declinations [0,+90]. ATCA observations were made in three campaigns: A3 started on 2014 April 7 and lasted for 30hr, A4 started on 2014 September 23 and lasted for 66hr, and A5 started on 2015 April 4 and lasted for 8hr. Observations in all three campaigns were recorded simultaneously in two bands centered at 5.5 and 9.0GHz. A total of 322 unassociated 3FGL fields with decl. above 0° were selected for observations with NRAO's Jansky VLA in this campaign (V2). Additionally, we observed the location of 2FGL J0423.4+5612, for which no data were recorded in our previous VLA survey. We reanalyzed our previous campaign V1 (Schinzel+ 2015, J/ApJS/217/4). The observations were conducted using the C-Band receiver covering the frequency range 4-8GHz. The observing time of 10hr was split into five segments. The first four segments were observed between 2015 March 16 and 21 under time approved through the NASA Fermi Guest Investigator program; an additional hour to complete the program was observed on 2015 April 16. See section 2 for further details. (5 data files).

Fermi Large Area Telescope Second Source Catalog

NASA Technical Reports Server (NTRS)

Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M; Allafort, A.; Antolini, E; Bonnell, J.; Cannon, A.; Celik O.; Corbet, R.;

VizieR Online Data Catalog: Sample of Fermi Blazars (Chen+, 2016)

NASA Astrophysics Data System (ADS)

Chen, Y.-Y.; Zhang, X.; Xiong, D.-R.; Wang, S.-J.; Yu, X.-L.

2016-04-01

We tried to select a large number of blazars with reliable redshift, radio core and extended radio luminosity at 1.4GHz. Firstly, we considered the following samples of blazars to get the radio core luminosity and extended luminosity at 1.4GHz: Kharb et al. (2010, J/ApJ/710/764), Antonucci & Ulvestad (1985ApJ...294..158A), Cassaro et al. (1999A&AS..139..601C), Murphy et al. (1993MNRAS.264..298M), Landt & Bignall (2008MNRAS.391..967L), Caccianiga & Marcha (2004, Cat. J/MNRAS/348/973), Giroletti et al. (2004). We cross-correlated these samples with the Fermi LAT Third Source Catalog (3FGL), and we acquired the 3FGL spectral index and energy flux at 0.1-100GeV from clean sources in 3FGL (Fermi-LAT Collaboration 2015, J/ApJS/218/23) Using these catalogs, we compiled 201 Fermi blazars. (1 data file).

Contemporaneous broadband observations of three high-redshift BL Lac objects

DOE PAGES

Ackerman, M.

2016-03-20

We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects, 3FGL J0022.1-1855 (z=0.689), 3FGL J0630.9-2406 (z > ~1.239), and 3FGL J0811.2-7529 (z=0.774), detected by Fermi with relatively flat GeV spectra. By observing simultaneously in the near-IR to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the GeV Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, withmore » poorer fits for high UV models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest redshift source 3FGL J0630.9-2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components.« less

Characterizing the Optical Variability of Bright Blazars: Variability-based Selection of Fermi Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Ruan, John J.; Anderson, Scott F.; MacLeod, Chelsea L.; Becker, Andrew C.; Burnett, T. H.; Davenport, James R. A.; Ivezić, Željko; Kochanek, Christopher S.; Plotkin, Richard M.; Sesar, Branimir; Stuart, J. Scott

2012-11-01

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of γ-ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability τ, and driving amplitudes on short timescales \\hat{\\sigma }. Imposing cuts on minimum τ and \\hat{\\sigma } allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several-arcminute error ellipses of γ-ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E >= 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r < 8'. We find that the suggested radio counterpart to Fermi source 2FGL J1649.6+5238 has optical variability consistent with other γ-ray blazars and is likely to be the γ-ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is ~3 years in the rest frame of the jet, in contrast with the ~320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics.

Fermi large area telescope second source catalog

DOE PAGES

Nolan, P. L.; Abdo, A. A.; Ackermann, M.; ...

2012-03-28

Here, we present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are fluxmore » measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. Furthermore, we provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. Finally, the 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes.« less

FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

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

Nolan, P. L.; Ajello, M.; Allafort, A.

We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurementsmore » in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.« less

Soluble FGL2, a novel effector molecule of activated hepatic stellate cells, regulates T-cell function in cirrhotic patients with hepatocellular carcinoma.

PubMed

Sun, Ying; Xi, Dong; Ding, Wen; Wang, Faxi; Zhou, Haili; Ning, Qin

2014-10-01

To investigate the effects of soluble FGL2 (sFGL2) secreted by hepatic stellate cells (HSCs) on immune suppression in cirrhotic patients with hepatocellular carcinoma (HCC). Serum sFGL2 levels were examined by ELISA in 40 patients with HCC, liver cirrhosis (LC) or chronic HBV (CHB) infection. A double staining of the immunofluorescence analysis of α-SMA and FGL2 was performed in two cirrhotic liver specimens. The expression of FGL2 in the LX2 cell line was analyzed by immunofluorescence, Western blot and flow cytometry. T-cells purified from HCC patients using magnetic beads were cultured with LX2 cells at different ratios with anti-CD3-stimulating or FGL2-blocking antibodies. The proliferation index (PI) of CD8 + T cells was assessed by flow cytometry, and the secretion of IFN-γ was measured by ELISA. sFGL2 levels are significantly higher in patients with HCC or LC compared with those with CHB (p = 0.0039/p = 0.0020). Among HCC patients, those with cirrhosis exhibited significantly higher levels of sFGL2 compared with non-cirrhotic individuals (p = 0.0108). The expressions of FGL2 and α-SMA overlapped in HSCs in liver specimens. FGL2 protein secreted by LX2 cells inhibited T-cell proliferation of HCC patients in a dose-dependent manner in vitro. The PI of CD8 + T cells was significantly enhanced following addition of FGL2 antibody to the culture system (LX2/T-cell ratio of 1:10, p = 0.002). The level of IFN-γ in mixed cultures was inversely correlated with the number of HSCs and was reversed by incubation with FGL2 blocking antibody. sFGL2 protein is a novel effector molecule of activated HSCs, which suppresses CD8 + T cell proliferation and interferon-γ production, and it subsequently might contribute to immune suppression during fibrosis and tumorigenesis in the liver.

VizieR Online Data Catalog: 231 AGN candidates from the 2FGL catalog (Doert+, 2014)

NASA Astrophysics Data System (ADS)

Doert, M.; Errando, M.

2016-01-01

The second Fermi-LAT source catalog (2FGL; Nolan et al. 2012, cat. J/ApJS/199/31) is the deepest all-sky survey available in the gamma-ray band. It contains 1873 sources, of which 576 remain unassociated. The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope started operations in 2008. In this work, machine-learning algorithms are used to identify unassociated sources in the 2FGL catalog with properties similar to gamma-ray-emitting Active Galactic Nuclei (AGN). This analysis finds 231 high-confidence AGN candidates (see Table3). (1 data file).

A statistical approach to recognize source classes for unassociated sources in the first Fermi-LAT catalog

DOE PAGES

Ackermann, M.; Ajello, M.; Allafort, A.; ...

2012-06-15

The Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of γ-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit γ rays, 630 of these sources are "unassociated" (i.e., have no obvious counterparts at other wavelengths).We employ two statistical analyses of the primary γ-ray characteristics for these unassociated sources in an effort to correlate their γ-ray properties with the active galactic nucleus (AGN) and pulsar populations in 1FGL. Based on the correlation results, we classify 221 AGN-like and 134 pulsar-likemore » sources in the 1FGL unassociated sources. Furthermore, the results of these source "classifications" appear to match the expected source distributions, especially at high Galactic latitudes. While useful for planning future multiwavelength follow-up observations, these analyses use limited inputs, and their predictions should not be considered equivalent to "probable source classes" for these sources. We also discuss multiwavelength results and catalog cross-correlations to date, and provide new source associations for 229 Fermi-LAT sources that had no association listed in the 1FGL catalog. By validating the source classifications against these new associations, we find that the new association matches the predicted source class in ~80% of the sources.« less

A STATISTICAL APPROACH TO RECOGNIZING SOURCE CLASSES FOR UNASSOCIATED SOURCES IN THE FIRST FERMI-LAT CATALOG

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

Ackermann, M.; Ajello, M.; Allafort, A.

The Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of {gamma}-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit {gamma} rays, 630 of these sources are 'unassociated' (i.e., have no obvious counterparts at other wavelengths). Here, we employ two statistical analyses of the primary {gamma}-ray characteristics for these unassociated sources in an effort to correlate their {gamma}-ray properties with the active galactic nucleus (AGN) and pulsar populations in 1FGL. Based on the correlation results, we classify 221 AGN-like andmore » 134 pulsar-like sources in the 1FGL unassociated sources. The results of these source 'classifications' appear to match the expected source distributions, especially at high Galactic latitudes. While useful for planning future multiwavelength follow-up observations, these analyses use limited inputs, and their predictions should not be considered equivalent to 'probable source classes' for these sources. We discuss multiwavelength results and catalog cross-correlations to date, and provide new source associations for 229 Fermi-LAT sources that had no association listed in the 1FGL catalog. By validating the source classifications against these new associations, we find that the new association matches the predicted source class in {approx}80% of the sources.« less

A Statistical Approach to Recognizing Source Classes for Unassociated Sources in the First FERMI-LAT Catalog

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Berenji, B.;

A statistical approach to recognize source classes for unassociated sources in the first Fermi-LAT catalog

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

Ackermann, M.; Ajello, M.; Allafort, A.

The Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of γ-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit γ rays, 630 of these sources are "unassociated" (i.e., have no obvious counterparts at other wavelengths).We employ two statistical analyses of the primary γ-ray characteristics for these unassociated sources in an effort to correlate their γ-ray properties with the active galactic nucleus (AGN) and pulsar populations in 1FGL. Based on the correlation results, we classify 221 AGN-like and 134 pulsar-likemore » sources in the 1FGL unassociated sources. Furthermore, the results of these source "classifications" appear to match the expected source distributions, especially at high Galactic latitudes. While useful for planning future multiwavelength follow-up observations, these analyses use limited inputs, and their predictions should not be considered equivalent to "probable source classes" for these sources. We also discuss multiwavelength results and catalog cross-correlations to date, and provide new source associations for 229 Fermi-LAT sources that had no association listed in the 1FGL catalog. By validating the source classifications against these new associations, we find that the new association matches the predicted source class in ~80% of the sources.« less

Research and characterisation of blazar candidates among the Fermi/LAT 3FGL catalogue using multivariate classifications

NASA Astrophysics Data System (ADS)

Lefaucheur, Julien; Pita, Santiago

2017-06-01

Context. In the recently published 3FGL catalogue, the Fermi/LAT collaboration reports the detection of γ-ray emission from 3034 sources obtained after four years of observations. The nature of 1010 of those sources is unknown, whereas 2023 have well-identified counterparts in other wavelengths. Most of the associated sources are labelled as blazars (1717/2023), but the BL Lac or FSRQ nature of 573 of these blazars is still undetermined. Aims: The aim of this study was two-fold. First, to significantly increase the number of blazar candidates from a search among the large number of Fermi/LAT 3FGL unassociated sources (case A). Second, to determine the BL Lac or FSRQ nature of the blazar candidates, including those determined as such in this work and the blazar candidates of uncertain type (BCU) that are already present in the 3FGL catalogue (case B). Methods: For this purpose, multivariate classifiers - boosted decision trees and multilayer perceptron neural networks - were trained using samples of labelled sources with no caution flag from the 3FGL catalogue and carefully chosen discriminant parameters. The decisions of the classifiers were combined in order to obtain a high level of source identification along with well controlled numbers of expected false associations. Specifically for case A, dedicated classifications were generated for high (| b | >10◦) and low (| b | ≤10◦) galactic latitude sources; in addition, the application of classifiers to samples of sources with caution flag was considered separately, and specific performance metrics were estimated. Results: We obtained a sample of 595 blazar candidates (high and low galactic latitude) among the unassociated sources of the 3FGL catalogue. We also obtained a sample of 509 BL Lacs and 295 FSRQs from the blazar candidates cited above and the BCUs of the 3FGL catalogue. The number of expected false associations is given for different samples of candidates. It is, in particular, notably low ( 9/425) for the sample of high-latitude blazar candidates from case A. Full Tables 5 and 7 are 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/602/A86

Fermi LAT detection of a GeV flare from blazar S5 1217+71

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2013-03-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar S5 1217+71, also known as TXS 1217+713 and 2FGL J1219.2+7107 in the second Fermi LAT catalog (2FGL, Nolan et al. 2012, ApJS, 199, 31) with VLBI coordinates, (J2000.0), R.A: 185.015118 deg, Dec.: +71.091981 deg (Petrov et al.

Examining the Fermi-LAT third source catalog in search of dark matter subhalos

DOE PAGES

Bertoni, Bridget; Hooper, Dan; Linden, Tim

2015-12-17

Dark matter annihilations taking place in nearby subhalos could appear as gamma-ray sources without detectable counterparts at other wavelengths. In this study, we consider the collection of unassociated gamma-ray sources reported by the Fermi Collaboration in an effort to identify the most promising dark matter subhalo candidates. While we identify 24 bright, high-latitude, non-variable sources with spectra that are consistent with being generated by the annihilations of ~ 20–70 GeV dark matter particles (assuming annihilations to bbar b), it is not possible at this time to distinguish these sources from radio-faint gamma-ray pulsars. Deeper multi-wavelength observations will be essential tomore » clarify the nature of these sources. It is notable that we do not find any such sources that are well fit by dark matter particles heavier than ~100 GeV. We also study the angular distribution of the gamma-rays from this set of subhalo candidates, and find that the source 3FGL J2212.5+0703 prefers a spatially extended profile (of width ~ 0.15°) over that of a point source, with a significance of 4.2σ (3.6σ after trials factor). Although not yet definitive, this bright and high-latitude gamma-ray source is well fit as a nearby subhalo of m χ ≃ 20–50 GeV dark matter particles (annihilating to bb¯) and merits further multi-wavelength investigation. As a result, based on the subhalo distribution predicted by numerical simulations, we derive constraints on the dark matter annihilation cross section that are competitive to those resulting from gamma-ray observations of dwarf spheroidal galaxies, the Galactic Center, and the extragalactic gamma-ray background.« less

Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2010-01-01

Topics include: Fermi LAT Collaboration groups; galactic results from LAT; a GeV, wide-field instrument; the 1FGL catalog, the Fermi LAT 1FGL source catalog, unidentified gamma-ray sources; variability in 1FGL sources; curvature in 1FGL sources; spectral-variability classification; pulsars and their wind nebulae; gamma-ray pulsars and MSPs; GeV PWN search; Crab pulsar and nebula; Vela X nebular of Vela pulsar; MSH 15-52; supernova remnants, resolved GeV sources, galactic transients, LAT unassociated transient detections; gamma rays from a nova; V407 Cyngi - a symbiotic nova; V407 Cygni: a variable star; and March 11 - a nova. Summary slides include pulsars everywhere, blazars, LAT as an electron detector, cosmic ray spectrum, the Large Area Telescope, the Fermi Observatory, LAT sensitivity with time, candidate gamma-ray events, on-orbit energy calibration and rate, a 1 year sky map, LAT automated science processing, reported GeV flares, early activity and spectacular flare, gamma-ray transients near the galactic plane , two early unassociated transients, counter part search - Fermi J0910-5404; counterpart search 3EG J0903-3531, and a new LAT transient - J1057-6027.

New Identification of the Mixed-Morphology Supernova Remnant G298.6-0.0 with Possible Gamma-Ray Association

NASA Technical Reports Server (NTRS)

Bamba, Aya; Sawada, Makoto; Nakano, Yuto; Terada, Yukikatsu; Hewitt, John; Petre, Robert; Angelini, Lorella

2015-01-01

We present an X-ray analysis on the Galactic supernova remnant (SNR) G298.6-0.0 observed with Suzaku. The X-ray image shows a center-filled structure inside a radio shell, implying that this SNR can be categorized as a mixed-morphology (MM) SNR. The spectrum is well reproduced by a single-temperature plasma model in ionization equilibrium, with a temperature of 0.78 (0.70-0.87) keV. The total plasma mass of 30M indicates that the plasma has an interstellar medium origin. The association with a GeV gamma-ray source, 3FGL J1214.0-6236, on the shell of the SNR is discussed, in comparison with other MMSNRs with GeV gamma-ray associations. It is found that the flux ratio between absorption-corrected thermal X-rays and GeV gamma-rays decreases as the physical size of MMSNRs becomes larger. The absorption-corrected thermal X-ray flux of G298.6-0.0 and the GeV gamma-ray flux of 3FGL J1214.0-6236 closely follow this trend, implying that 3FGL J1214.0-6236 is likely to be a GeV counterpart of G298.6-0.0.

Milagro Observations of Potential TeV Emitters

NASA Astrophysics Data System (ADS)

Abeysekara, Anushka; Linnemann, James

2012-03-01

We searched for point sources in Milagro sky maps at the locations in four catalogs of potential TeV emitting sources. Our candidates are selected from the Fermi 2FGL pulsars, Fermi 2FGL extragalactic sources, TeVCat extragalactic sources, and from the BL Lac TeV Candidate list published by Costamante and Ghisellini in 2002. The False Discovery Rate (FDR) statistical procedure is used to select the sources. The FDR procedure controls the fraction of false detections. Our results are presented in this talk.

Dark matter subhalos and unidentified sources in the Fermi 3FGL source catalog

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

Schoonenberg, Djoeke; Gaskins, Jennifer; Bertone, Gianfranco

2016-05-01

If dark matter consists of weakly interacting massive particles (WIMPs), dark matter subhalos in the Milky Way could be detectable as gamma-ray point sources due to WIMP annihilation. In this work, we perform an updated study of the detectability of dark matter subhalos as gamma-ray sources with the Fermi Large Area Telescope (Fermi LAT). We use the results of the Via Lactea II simulation, scaled to the Planck 2015 cosmological parameters, to predict the local dark matter subhalo distribution. Under optimistic assumptions for the WIMP parameters—a 40 GeV particle annihilating to b b-bar with a thermal cross-section, as required tomore » explain the Galactic center GeV excess—we predict that at most ∼ 10 subhalos might be present in the third Fermi LAT source catalog (3FGL). This is a smaller number than has been predicted by prior studies, and we discuss the origin of this difference. We also compare our predictions for the detectability of subhalos with the number of subhalo candidate sources in 3FGL, and derive upper limits on the WIMP annihilation cross-section as a function of the particle mass. If a dark matter interpretation could be excluded for all 3FGL sources, our constraints would be competitive with those found by indirect searches using other targets, such as known Milky Way satellite galaxies.« less

3FGLzoo: classifying 3FGL unassociated Fermi-LAT γ-ray sources by artificial neural networks

NASA Astrophysics Data System (ADS)

Salvetti, D.; Chiaro, G.; La Mura, G.; Thompson, D. J.

2017-09-01

In its first four years of operation, the Fermi-Large Area Telescope (LAT) detected 3033 γ-ray emitting sources. In the Fermi-LAT Third Source Catalogue (3FGL) about 50 per cent of the sources have no clear association with a likely γ-ray emitter. We use an artificial neural network algorithm aimed at distinguishing BL Lacs from FSRQs to investigate the source subclass of 559 3FGL unassociated sources characterized by γ-ray properties very similar to those of active galactic nuclei. Based on our method, we can classify 271 objects as BL Lac candidates, 185 as FSRQ candidates, leaving only 103 without a clear classification. We suggest a new zoo for γ-ray objects, where the percentage of sources of uncertain type drops from 52 per cent to less than 10 per cent. The result of this study opens up new considerations on the population of the γ-ray sky, and it will facilitate the planning of significant samples for rigorous analyses and multiwavelength observational campaigns.

Fermi Large Area Telescope third source catalog

DOE PAGES

Acero, F.; Ackermann, M.; Ajello, M.; ...

2015-06-12

Here, we present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV–300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse γ-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources abovemore » $$4\\sigma $$ significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. As a result, from source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is ~3% at 1 GeV.« less

Fermi Large Area Telescope Second Source Catalog

NASA Astrophysics Data System (ADS)

Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Cañadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; DeCesar, M. E.; DeKlotz, M.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Van Etten, A.; Van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

2012-04-01

We present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes. We dedicate this paper to the memory of our colleague Patrick Nolan, who died on 2011 November 6. His career spanned much of the history of high-energy astronomy from space and his work on the Large Area Telescope (LAT) began nearly 20 years ago when it was just a concept. Pat was a central member in the operation of the LAT collaboration and he is greatly missed.

FAST's Discovery of a New Millisecond Pulsar (MSP) toward the Fermi-LAT unassociated source 3FGL J0318.1+0252

NASA Astrophysics Data System (ADS)

Wang, Pei; Li, Di; Zhu, Weiwei; Zhang, Chengmin; Yan, Jun; Hou, Xian; Clark, Colin J.; Saz Parkinson, Pablo M.; Michelson, Peter F.; Ferrara, Elizabeth C.; Thompson, David J.; Smith, David A.; Ray, Paul S.; Kerr, Matthew; Shen, Zhiqiang; Wang, Na; Fermi-LAT Collaboration

2018-04-01

The Five hundred-meter Aperture Spherical radio Telescope (FAST), operated by the National Astronomical Observatories, Chinese Academy of Sciences, has discovered a radio millisecond pulsar (MSP) coincident with the unassociated gamma-ray source 3FGL J0318.1+0252 (Acero et al. 2015 ApJS, 218, 23), also known as FL8Y J0318.2+0254 in the recently released Fermi Large Area Telescope (LAT) 8-year Point Source List (FL8Y).

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

NASA Astrophysics Data System (ADS)

Barr, E. D.; Guillemot, L.; Champion, D. J.; Kramer, M.; Eatough, R. P.; Lee, K. J.; Verbiest, J. P. W.; Bassa, C. G.; Camilo, F.; Çelik, Ö.; Cognard, I.; Ferrara, E. C.; Freire, P. C. C.; Janssen, G. H.; Johnston, S.; Keith, M.; Lyne, A. G.; Michelson, P. F.; Parkinson, P. M. Saz; Ransom, S. M.; Ray, P. S.; Stappers, B. W.; Wood, K. S.

2013-02-01

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). This survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M_{c,{min}} ˜ 0.0137 M_{⊙}, indicative of `black widow' type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection of a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. The reasons behind the seemingly low yield of discoveries are also discussed.

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

DOE PAGES

Barr, E. D.; Guillemot, L.; Champion, D. J.; ...

2012-12-21

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). In addition, this survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M c,min~0.0137M⊙, indicative of ‘black widow’ type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection ofmore » a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. Lastly, the reasons behind the seemingly low yield of discoveries are also discussed.« less

X-Ray and Optical Study of the Gamma-ray Source 3FGL J0838.8–2829: Identification of a Candidate Millisecond Pulsar Binary and an Asynchronous Polar

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

Halpern, Jules P.; Bogdanov, Slavko; Thorstensen, John R., E-mail: jules@astro.columbia.edu

2017-04-01

We observed the field of the Fermi source 3FGL J0838.8−2829 in optical and X-rays, initially motivated by the cataclysmic variable (CV) 1RXS J083842.1−282723 that lies within its error circle. Several X-ray sources first classified as CVs have turned out to be γ -ray emitting millisecond pulsars (MSPs). We find that 1RXS J083842.1−282723 is in fact an unusual CV, a stream-fed asynchronous polar in which accretion switches between magnetic poles (that are ≈120° apart) when the accretion rate is at minimum. High-amplitude X-ray modulation at periods of 94.8 ± 0.4 minutes and 14.7 ± 1.2 hr are seen. The former appearsmore » to be the spin period, while the latter is inferred to be one-third of the beat period between the spin and the orbit, implying an orbital period of 98.3 ± 0.5 minutes. We also measure an optical emission-line spectroscopic period of 98.413 ± 0.004 minutes, which is consistent with the orbital period inferred from the X-rays. In any case, this system is unlikely to be the γ -ray source. Instead, we find a fainter variable X-ray and optical source, XMMU J083850.38−282756.8, that is modulated on a timescale of hours in addition to exhibiting occasional sharp flares. It resembles the black widow or redback pulsars that have been discovered as counterparts of Fermi sources, with the optical modulation due to heating of the photosphere of a low-mass companion star by, in this case, an as-yet undetected MSP. We propose XMMU J083850.38−282756.8 as the MSP counterpart of 3FGL J0838.8−2829.« less

Milagro Observations of Potential TeV Emitters

NASA Technical Reports Server (NTRS)

Abdo, A. A.; Abeysekara, A. U.; Allen, B. T.; Aune, T.; Barber, A. S.; Berley, D.; Braun, J.; Chen, C.; Christopher, G. E.; DeYoung, T.;

Fermi-LAT Observations of High-Energy Gamma-Ray Emission Toward the Galactic Center

DOE PAGES

Ajello, M.

2016-02-26

The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission towards the Galactic centre (GC) in high-energy γ-rays. This paper describes the analysis of data taken during the first 62 months of the mission in the energy range 1 - 100 GeV from a 15° X15° region about the direction of the GC, and implications for the interstellar emissions produced by cosmic ray (CR) particles interacting with the gas and radiation fields in the inner Galaxy and for the point sources detected. Specialised interstellar emission models (IEMs) are constructed that enable separation ofmore » the γ-ray emission from the inner ~ 1 kpc about the GC from the fore- and background emission from the Galaxy. Based on these models, the interstellar emission from CR electrons interacting with the interstellar radiation field via the inverse Compton (IC) process and CR nuclei inelastically scattering off the gas producing γ-rays via π⁰ decays from the inner ~ 1 kpc is determined. The IC contribution is found to be dominant in the region and strongly enhanced compared to previous studies. A catalog of point sources for the 15 °X 15 °region is self-consistently constructed using these IEMs: the First Fermi–LAT Inner Galaxy point source Catalog (1FIG). The spatial locations, fluxes, and spectral properties of the 1FIG sources are presented, and compared with γ-ray point sources over the same region taken from existing catalogs, including the Third Fermi–LAT Source Catalog (3FGL). In general, the spatial density of 1FIG sources differs from those in the 3FGL, which is attributed to the different treatments of the interstellar emission and energy ranges used by the respective analyses. Three 1FIG sources are found to spatially overlap with supernova remnants (SNRs) listed in Green’s SNR catalog; these SNRs have not previously been associated with high-energy γ-ray sources. Most 3FGL sources with known multi-wavelength counterparts are also found. However, the majority of 1FIG point sources are unassociated. After subtracting the interstellar emission and point-source contributions from the data a residual is found that is a sub-dominant fraction of the total flux. But, it is brighter than the γ-ray emission associated with interstellar gas in the inner ~ 1 kpc derived for the IEMs used in this paper, and comparable to the integrated brightness of the point sources in the region for energies & 3 GeV. If spatial templates that peak toward the GC are used to model the positive residual and included in the total model for the 1515°X° region, the agreement with the data improves, but they do not account for all the residual structure. The spectrum of the positive residual modelled with these templates has a strong dependence on the choice of IEM.« less

New High-z BL Lacs Using the Photometric Method with Swift and SARA

NASA Astrophysics Data System (ADS)

Kaur, A.; Rau, A.; Ajello, M.; Domínguez, A.; Paliya, V. S.; Greiner, J.; Hartmann, D. H.; Schady, P.

2018-06-01

BL Lacertae (BL Lac) objects are prominent members of the third Fermi Large Area Telescope catalog of γ-ray sources. Half of the members of the BL Lac population (∼300) lack redshift measurements, which is due to the absence of lines in their optical spectra, thereby making it difficult to utilize spectroscopic methods. Our photometric dropout technique can be used to establish the redshift for a fraction of these sources. This work employed six filters mounted on the Swift-UVOT and four optical filters on two telescopes, the 0.65 m SARA-CTIO in Chile and 1.0 m SARA-ORM in the Canary Islands, Spain. A sample of 15 sources was extracted from the Swift archival data for which six filter UVOT observations were conducted. By complementing the Swift observations with the SARA ones, we were able to discover two high-redshift sources: 3FGL J1155.4-3417 and 3FGL J1156.7–2250 at z={1.83}-0.13+0.10 and z={1.73}-0.19+0.11, respectively, resulting from the dropouts in the power-law template fits to these data. The discoveries add to the important (26 total) sample of high-redshift BL Lacs. While the sample of high-z BL Lacs is still rather small, these objects do not seem to fit well within known schemes of the blazar population and represent the best probes of the extragalactic background light.

Fermi LAT detection of a GeV gamma-ray flare from blazar CGRaBS J0809+5341 (87GB 080551.6+535010)

NASA Astrophysics Data System (ADS)

Gasparrini, Dario

2017-10-01

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray emission from a source positionally consistent with the flat spectrum radio quasar CGRaBS J0809+5341 (also known as 87GB 080551.6+535010, BZQ J0809+5341 and 3FGL J0809.5+5342) with radio coordinates (J2000) R.A.: 122.4238862 deg, Dec.: 53.6903033 deg (Petrov et al. 2011, AJ, 142, 89). This blazar has a redshift z = 2.133 (Healey et al. 2008, ApJS, 175, 97). Preliminary analysis indicates that on 2017 October 26, CGRaBS J0809+5341 was in a high state with a daily averaged gamma-ray flux (E > 100 MeV) of (0.23+/-0.15) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 20 times greater than its four-year average flux reported in the third Fermi-LAT source catalog (3FGL, Acero et al. 2015, ApJS, 218, 23). Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue.

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

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

Schinzel, Frank K.; Petrov, Leonid; Taylor, Gregory B.

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

Optical-NIR spectroscopy of the puzzling γ-ray source 3FGL 1603.9-4903/PMN J1603-4904 with X-Shooter

NASA Astrophysics Data System (ADS)

Goldoni, P.; Pita, S.; Boisson, C.; Müller, C.; Dauser, T.; Jung, I.; Krauß, F.; Lenain, J.-P.; Sol, H.

2016-02-01

Context. The Fermi/LAT instrument has detected about two thousand extragalactic high energy (E ≥ 100 MeV) γ-ray sources. One of the brightest is 3FGL J1603.9-4903; it is associated to the radio source PMN J1603-4904. Its nature is not yet clear, it could be either a very peculiar BL Lac or a compact symmetric object radio source which are considered as the early stage of a radio galaxy. The latter, if confirmed, would be the first detection in γ-rays for this class of objects. A redshift z = 0.18 ± 0.01 has recently been claimed on the basis of the detection of a single X-ray line at 5.44 ± 0.05 keV which has been interpreted as a 6.4 keV (rest frame) fluorescent line. Aims: We aim to investigate the nature of 3FGL J1603.9-4903/PMN J1603-4904 using optical-to near-IR (NIR) spectroscopy. Methods: We observed PMN J1603-4904 with the UV-NIR VLT/X-Shooter spectrograph for two hours. We extracted spectra in the visible and NIR range that we calibrated in flux and corrected for telluric absorption. We systematically searched for absorption and emission features. Results: The source was detected starting from ~6300 Å down to 24 000 Å with an intensity similar to that of its 2MASS counterpart and a mostly featureless spectrum. The continuum lacks absorption features and thus is non-stellar in origin and most likely non-thermal. In addition to this spectrum, we detected three emission lines that we interpret as the Hα-[NII] complex, the [SII]λ,λ6716, 6731 doublet and the [SIII]λ 9530 line; we obtain a redshift estimate of z = 0.2321 ± 0.0004. The line ratios suggest that a LINER/Seyfert nucleus powers the emission. This new redshift measurement implies that the X-ray line previously detected should be interpreted as a 6.7 keV line which is very peculiar. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under program 095.B-0400(A). The raw FITS data files are available in the ESO archive.

Unveiling the Gamma-Ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics

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

Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza

The source-count distribution as a function of their flux, dN/dS, is one of the main quantities characterizing gamma-ray source populations. In this paper, we employ statistical properties of the Fermi Large Area Telescope (LAT) photon counts map to measure the composition of the extragalactic gamma-ray sky at high latitudes (|b| greater-than or slanted equal to 30°) between 1 and 10 GeV. We present a new method, generalizing the use of standard pixel-count statistics, to decompose the total observed gamma-ray emission into (a) point-source contributions, (b) the Galactic foreground contribution, and (c) a truly diffuse isotropic background contribution. Using the 6more » yr Fermi-LAT data set (P7REP), we show that the dN/dS distribution in the regime of so far undetected point sources can be consistently described with a power law with an index between 1.9 and 2.0. We measure dN/dS down to an integral flux of ~2 x 10 -11cm -2s -1, improving beyond the 3FGL catalog detection limit by about one order of magnitude. The overall dN/dS distribution is consistent with a broken power law, with a break at 2.1 +1.0 -1.3 x 10 -8cm -2s -1. The power-law index n 1 = 3.1 +0.7 -0.5 for bright sources above the break hardens to n 2 = 1.97 ± 0.03 for fainter sources below the break. A possible second break of the dN/dS distribution is constrained to be at fluxes below 6.4 x 10 -11cm -2s -1 at 95% confidence level. Finally, the high-latitude gamma-ray sky between 1 and 10 GeV is shown to be composed of ~25% point sources, ~69.3% diffuse Galactic foreground emission, and ~6% isotropic diffuse background.« less

Unveiling the Gamma-Ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics

DOE PAGES

Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; ...

2016-07-26

The source-count distribution as a function of their flux, dN/dS, is one of the main quantities characterizing gamma-ray source populations. In this paper, we employ statistical properties of the Fermi Large Area Telescope (LAT) photon counts map to measure the composition of the extragalactic gamma-ray sky at high latitudes (|b| greater-than or slanted equal to 30°) between 1 and 10 GeV. We present a new method, generalizing the use of standard pixel-count statistics, to decompose the total observed gamma-ray emission into (a) point-source contributions, (b) the Galactic foreground contribution, and (c) a truly diffuse isotropic background contribution. Using the 6more » yr Fermi-LAT data set (P7REP), we show that the dN/dS distribution in the regime of so far undetected point sources can be consistently described with a power law with an index between 1.9 and 2.0. We measure dN/dS down to an integral flux of ~2 x 10 -11cm -2s -1, improving beyond the 3FGL catalog detection limit by about one order of magnitude. The overall dN/dS distribution is consistent with a broken power law, with a break at 2.1 +1.0 -1.3 x 10 -8cm -2s -1. The power-law index n 1 = 3.1 +0.7 -0.5 for bright sources above the break hardens to n 2 = 1.97 ± 0.03 for fainter sources below the break. A possible second break of the dN/dS distribution is constrained to be at fluxes below 6.4 x 10 -11cm -2s -1 at 95% confidence level. Finally, the high-latitude gamma-ray sky between 1 and 10 GeV is shown to be composed of ~25% point sources, ~69.3% diffuse Galactic foreground emission, and ~6% isotropic diffuse background.« less

Fermi LAT detection of a GeV flare from blazar TXS 0943+105

NASA Astrophysics Data System (ADS)

Ciprini, S.

2014-07-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar TXS 0943+105, also known as GB6 J0946+1016, MG1 J094636+1017 and 2FGL J0946.5+1015 in the second Fermi LAT catalog (2FGL, Nolan et al. ...

Correlation of fibrinogen-like protein 2 with progression of acute pancreatitis in rats

PubMed Central

Ye, Xiao-Hua; Chen, Tan-Zhou; Huai, Jia-Ping; Lu, Guang-Rong; Zhuge, Xiao-Ju; Chen, Ren-Pin; Chen, Wu-Jie; Wang, Chen; Huang, Zhi-Ming

2013-01-01

AIM: To examine fibrinogen-like protein 2 (fgl2) expression during taurocholate-induced acute pancreatitis progression in rats and its correlation with pancreatic injury severity. METHODS: Forty-eight male Sprague-Dawley rats were randomly divided into the severe acute pancreatitis (SAP) group (n = 24) and the sham operation (SO) group (n = 24). Sodium taurocholate (4% at doses of 1 mL/kg body weight) was retrogradely injected into the biliopancreatic ducts of the rats to induce SAP. Pancreatic tissues were prepared immediately after sacrifice. At the time of sacrifice, blood was obtained for determination of serum amylase activity and isolation of peripheral blood mononuclear cells (PBMCs). Pancreatic tissue specimens were obtained for routine light microscopy including hematoxylin and eosin staining, and the severity of pancreatic injury was evaluated 1, 4 and 8 h after induction. Expression of fgl2 mRNA was measured in the pancreas and PBMCs using reverse transcription polymerase chain reaction. Expression of fgl2 protein was evaluated in pancreatic tissues using Western blotting and immunohistochemical staining. Masson staining was also performed to observe microthrombosis. RESULTS: At each time point, levels of fgl2 mRNAs in pancreatic tissues and PBMCs were higher (P < 0.05) in the SAP group than in the SO group. For pancreatic tissue in SAP vs SO, the levels were: after 1 h, 3.911 ± 1.277 vs 1.000 ± 0.673; after 4 h, 9.850 ± 3.095 vs 1.136 ± 0.609; and after 8 h, 12.870 ± 3.046 vs 1.177 ± 0.458. For PBMCs in SAP vs SO, the levels were: after 1 h, 2.678 ± 1.509 vs 1.000 ± 0.965; after 4 h, 6.922 ± 1.984 vs 1.051 ± 0.781; and after 8 h, 13.533 ± 6.575 vs 1.306 ± 1.179. Levels of fgl2 protein expression as determined by Western blotting and immunohistochemical staining were markedly up-regulated (P < 0.001) in the SAP group compared with those in the SO group. For Western blotting in SAP vs SO, the results were: after 1 h, 2.183 ± 0.115 vs 1.110 ± 0.158; after 4 h, 2.697 ± 0.090 vs 0.947 ± 0.361; and after 8 h, 3.258 ± 0.094 vs 1.208 ± 0.082. For immunohistochemical staining in SAP vs SO, the results were: after 1 h, 1.793 ± 0.463 vs 0.808 ± 0.252; after 4 h, 4.535 ± 0.550 vs 0.871 ± 0.318; and after 8 h, 6.071 ± 0.941 vs 1.020 ± 0.406. Moreover, we observed a positive correlation in the pancreas (r = 0.852, P < 0.001) and PBMCs (r = 0.735, P < 0.001) between fgl2 expression and the severity of pancreatic injury. Masson staining showed that microthrombosis (%) in rats with SAP was increased (P < 0.001) compared with that in the SO group and it was closely correlated with fgl2 expression in the pancreas (r = 0.842, P < 0.001). For Masson staining in SAP vs SO, the results were: after 1 h, 26.880 ± 9.031 vs 8.630 ± 3.739; after 4 h, 53.750 ± 19.039 vs 8.500 ± 4.472; and after 8 h, 80.250 ± 12.915 vs 10.630 ± 7.003. CONCLUSION: Microthrombosis due to fgl2 overexpression contributes to pancreatic impairment in rats with SAP, and fgl2 level may serve as a biomarker during early stages of disease. PMID:23674850

Confirming the gamma-ray blazar nature of the low energy counterpart QSO GB6 J1604+5714 of 2FGL J1604.6+5710 with WISE

NASA Astrophysics Data System (ADS)

Massaro, F.; D'Abrusco, R.; Paggi, A.

2012-06-01

Following the rapid optical variability detected in the QSO GB6 J1604+5714 (=BZQJ1604+5714) (ATEL #4184), associated to the gamma-ray source 2FGL J1604.6+5710 (=1FGL J1604.3+5710) in Nolan et al. (2012 ApJS, 199, 31), we searched in the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010 AJ, 140, 1868) catalog at the VLBI position of the QSO GB6 J1604+5714 (R.A.(J2000): 16h04m37.3546s, Dec.(J2000): +57d14m36.660s) reported in Beasley et al......

Fermi LAT detection of a gamma-ray flare from FSRQ S5 1044+71

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Carpenter, Bryce; Dutka, Michael

2013-04-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux 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). Localization analysis has ruled out the nearby source 2FGL J1049.7+7240 as a possible counterpart. S5 1044+71 has coordinates RA=10h48m27.6199s DEC=+71d43m35.938s, J2000, (Johnston et al.

XMM-Newton observations of the Galactic Centre Region - II. The soft-thermal emission

NASA Astrophysics Data System (ADS)

Heard, V.; Warwick, R. S.

2013-09-01

We have extended our earlier study of the X-ray emission emanating from the central 100 pc × 100 pc region of our Galaxy to an investigation of several features prominent in the soft X-ray (2-4.5 keV) band. We focus on three specific structures: a putative bipolar outflow from the vicinity of Sgr A*; a high surface brightness region located roughly 12 arcmin (25 pc) to the north-east of Sgr A* and a lower surface brightness extended loop feature seen to the south of Sgr A*. We show, unequivocally, that all three structures are thermal in nature and have similar temperatures (kT ≈ 1 keV). The inferred X-ray luminosities lie in the range (2-10) × 1034 erg s-1. In the case of the bipolar feature we suggest that the hot plasma is produced by the shock heating of the winds from massive stars within the Central Cluster, possibly collimated by the Circumnuclear Disc. Alternatively the outflow may be driven by outbursts on Sgr A*, which follow tidal disruption events occurring at a rate of roughly one every 4000 yr. The north-east enhancement is centred on a candidate pulsar wind nebula which has a relatively hard non-thermal X-ray spectrum. We suggest that the coincident soft-thermal emission traces the core of a new thermal-composite supernova remnant, designated as SNR G0.13-0.12. There is no clear evidence for an associated radio shell but such a feature may be masked by the bright emission of the nearby Radio Arc and other filamentary structures. SNR G0.13-0.12 is very likely interacting with the nearby molecular cloud, G0.11-0.11, and linked to the Fermi source, 2FGL J1746.4-2851c. Finally we explore a previous suggestion that the elliptically shaped X-ray loop to the south of Sgr A*, of maximum extent ˜45 pc, represents the shell of a superbubble located in the GC region. Although plausible, the interpretation of this feature in terms a coherent physical structure awaits confirmation.

A significant hardening and rising shape detected in the MeV/GeV νF ν spectrum from the recently discovered very-high-energy blazar S4 0954+65 during the bright optical flare in 2015 February

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

Tanaka, Yasuyuki T.; Becerra Gonzalez, Josefa; Itoh, Ryosuke

2016-05-23

In this paper, we report on Fermi Large Area Telescope (LAT) and multi-wavelength results on the recently discovered very-high-energy (VHE, E > 100 GeV) blazar S4 0954+65 (z = 0.368) during an exceptionally bright optical flare in 2015 February. During the time period (2015 February 13/14, or MJD 57067) when the MAGIC telescope detected VHE γ-ray emission from the source, the Fermi-LAT data indicated a significant spectral hardening at GeV energies, with a power-law photon index of 1.8 ± 0.1—compared with the 3FGL (The Fermi LAT 4-Year Point Source Catalog) value (averaged over four years of observation) of 2.34 ±more » 0.04. In contrast, Swift X-Ray Telescope data showed a softening of the X-ray spectrum, with a photon index of 1.72 ± 0.08 (compared with 1.38 ± 0.03 averaged during the flare from MJD 57066 to 57077), possibly indicating a modest contribution of synchrotron photons by the highest-energy electrons superposed on the inverse Compton component. Fitting of the quasi-simultaneous (<1 d) broad-band spectrum with a one-zone synchrotron plus inverse-Compton model revealed that GeV/TeV emission could be produced by inverse-Compton scattering of external photons from the dust torus. Finally, we emphasize that a flaring blazar showing high flux of ≳1.0 × 10 -6 photons cm -2s -1 (E > 100 MeV) and a hard spectral index of ΓGeV < 2.0 detected by Fermi-LAT on daily timescales is a promising target for TeV follow-up by ground-based Cherenkov telescopes to discover high-redshift blazars, investigate their temporal variability and spectral features in the VHE band, and also constrain the intensity of the extragalactic background light.« less

High-redshift Blazars through NuSTAR eyes

DOE PAGES

Marcotulli, L.; Paliya, V. S.; Ajello, M.; ...

2017-04-20

The most powerful sources among the blazar family are MeV blazars. Often detected at z > 2, they usually display high X- and γ-ray luminosities, larger-than-average jet powers, and black hole masses ≳10 9 M ⊙. In the present work, we perform a multiwavelength study of three high-redshift blazars: 3FGL J0325.5+2223 (z = 2.06), 3FGL J0449.0+1121 (z = 2.15), and 3FGL J0453.2–2808 (z = 2.56), analyzing quasi-simultaneous data from GROND, Swift-UVOT and XRT, Nuclear Spectroscopic Telescope Array (NuSTAR), and Fermi-LAT. Our main focus is on the hard X-ray band recently unveiled by NuSTAR (3–79 keV) where these objects show amore » hard spectrum that enables us to constrain the inverse Compton (IC) peak and the jet power. We found that all three targets resemble the most powerful blazars, with the synchrotron peak located in the submillimeter range and the IC peak in the MeV range, and therefore belong to the MeV blazar class. Using a simple one-zone leptonic emission model to reproduce the spectral energy distributions, we conclude that a simple combination of synchrotron and accretion disk emission reproduces the infrared–optical spectra, while the X-ray to γ-ray part is well reproduced by the IC scattering of low-energy photons supplied by the broad-line region. The black hole masses for each of the three sources are calculated to be ≳4 × 10 8 M ⊙. Finally, the three studied sources have jet power at the level of, or beyond, the accretion luminosity.« less

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

Marcotulli, L.; Paliya, V. S.; Ajello, M.

The most powerful sources among the blazar family are MeV blazars. Often detected at z > 2, they usually display high X- and γ -ray luminosities, larger-than-average jet powers, and black hole masses ≳10{sup 9} M {sub ☉}. In the present work, we perform a multiwavelength study of three high-redshift blazars: 3FGL J0325.5+2223 ( z = 2.06), 3FGL J0449.0+1121 ( z = 2.15), and 3FGL J0453.2−2808 ( z = 2.56), analyzing quasi-simultaneous data from GROND, Swift -UVOT and XRT, Nuclear Spectroscopic Telescope Array ( NuSTAR ), and Fermi -LAT. Our main focus is on the hard X-ray band recently unveiledmore » by NuSTAR (3–79 keV) where these objects show a hard spectrum that enables us to constrain the inverse Compton (IC) peak and the jet power. We found that all three targets resemble the most powerful blazars, with the synchrotron peak located in the submillimeter range and the IC peak in the MeV range, and therefore belong to the MeV blazar class. Using a simple one-zone leptonic emission model to reproduce the spectral energy distributions, we conclude that a simple combination of synchrotron and accretion disk emission reproduces the infrared–optical spectra, while the X-ray to γ -ray part is well reproduced by the IC scattering of low-energy photons supplied by the broad-line region. The black hole masses for each of the three sources are calculated to be ≳4 × 10{sup 8} M {sub ☉}. The three studied sources have jet power at the level of, or beyond, the accretion luminosity.« less

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

Marcotulli, L.; Paliya, V. S.; Ajello, M.

The most powerful sources among the blazar family are MeV blazars. Often detected at z > 2, they usually display high X- and γ-ray luminosities, larger-than-average jet powers, and black hole masses ≳10 9 M ⊙. In the present work, we perform a multiwavelength study of three high-redshift blazars: 3FGL J0325.5+2223 (z = 2.06), 3FGL J0449.0+1121 (z = 2.15), and 3FGL J0453.2–2808 (z = 2.56), analyzing quasi-simultaneous data from GROND, Swift-UVOT and XRT, Nuclear Spectroscopic Telescope Array (NuSTAR), and Fermi-LAT. Our main focus is on the hard X-ray band recently unveiled by NuSTAR (3–79 keV) where these objects show amore » hard spectrum that enables us to constrain the inverse Compton (IC) peak and the jet power. We found that all three targets resemble the most powerful blazars, with the synchrotron peak located in the submillimeter range and the IC peak in the MeV range, and therefore belong to the MeV blazar class. Using a simple one-zone leptonic emission model to reproduce the spectral energy distributions, we conclude that a simple combination of synchrotron and accretion disk emission reproduces the infrared–optical spectra, while the X-ray to γ-ray part is well reproduced by the IC scattering of low-energy photons supplied by the broad-line region. The black hole masses for each of the three sources are calculated to be ≳4 × 10 8 M ⊙. Finally, the three studied sources have jet power at the level of, or beyond, the accretion luminosity.« less

Cut-off characterisation of energy spectra of bright fermi sources: Current instrument limits and future possibilities

NASA Astrophysics Data System (ADS)

Romoli, C.; Taylor, A. M.; Aharonian, F.

2017-02-01

In this paper some of the brightest GeV sources observed by the Fermi-LAT were analysed, focusing on their spectral cut-off region. The sources chosen for this investigation were the brightest blazar flares of 3C 454.3 and 3C 279 and the Vela pulsar with a reanalysis with the latest Fermi-LAT software. For the study of the spectral cut-off we first explored the Vela pulsar spectrum, whose statistics in the time interval of the 3FGL catalog allowed strong constraints to be obtained on the parameters. We subsequently performed a new analysis of the flaring blazar SEDs. For these sources we obtained constraints on the cut-off parameters under the assumption that their underlying spectral distribution is described by a power-law with a stretched exponential cut-off. We then highlighted the significant potential improvements on such constraints by observations with next generation ground based Cherenkov telescopes, represented in our study by the Cherenkov Telescope Array (CTA). Adopting currently available simulations for this future observatory, we demonstrate the considerable improvement in cut-off constraints achievable by observations with this new instrument when compared with that achievable by satellite observations.

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

Nayeb-Hashemi, Hamed; Desai, Anal; Demchev, Valeriy

Fibrinogen like protein-1 (Fgl1) is a predominantly liver expressed protein that has been implicated as both a hepatoprotectant and a hepatocyte mitogen. Fgl1 expression is decreased in hepatocellular carcinoma (HCC) and its loss correlates with a poorly differentiated phenotype. To better elucidate the role of Fgl1 in hepatocarcinogenesis, we treated mice wild type or null for Fgl1 with diethyl nitrosamine and monitored for incidence of hepatocellular cancer. We find that mice lacking Fgl1 develop HCC at more than twice the rate of wild type mice. We show that hepatocellular cancers from Fgl1 null mice are molecularly distinct from those ofmore » the wild type mice. In tumors from Fgl1 null mice there is enhanced activation of Akt and downstream targets of the mammalian target of rapamycin (mTOR). In addition, there is paradoxical up regulation of putative hepatocellular cancer tumor suppressors; tripartite motif-containing protein 35 (Trim35) and tumor necrosis factor super family 10b (Tnfrsf10b). Taken together, these findings suggest that Fgl1 acts as a tumor suppressor in hepatocellular cancer through an Akt dependent mechanism and supports its role as a potential therapeutic target in HCC. - Highlights: • Fgl1 knockout mice (Fgl1KO) are more prone to carcinogen-induced liver cancer compared to wild type (WT) mates. • Tumors from the Fgl1KO are molecularly distinct with enhanced Akt and mTOR activity in comparison with Fgl1WT tumors. • Tumors from the Fgl1KO have enhanced expression of Trim35 and Tnfrsf10b, putative HCC tumor suppressors.« less

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

Migliori, G.; Loh, A.; Corbel, S.

We report the γ -ray detection of a young radio galaxy, PKS 1718−649, belonging to the class of compact symmetric objects (CSOs), with the Large Area Telescope (LAT) on board the Fermi satellite. The third Fermi Gamma-ray LAT catalog (3FGL) includes an unassociated γ -ray source, 3FGL J1728.0−6446, located close to PKS 1718−649. Using the latest Pass 8 calibration, we confirm that the best-fit 1 σ position of the γ -ray source is compatible with the radio location of PKS 1718−649. Cross-matching of the γ -ray source position with the positions of blazar sources from several catalogs yields negative results.more » Thus, we conclude that PKS 1718−649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS ∼ 36 (>5 σ ) with a best-fit photon spectral index Γ = 2.9 ± 0.3 and a 0.1–100 GeV photon flux density F {sub 0.1−100} {sub GeV} = (11.5 ± 0.3) × 10{sup −9} ph cm{sup −2} s{sup −1}. We argue that the linear size (∼2 pc), the kinematic age (∼100 years), and the source distance ( z = 0.014) make PKS 1718−649 an ideal candidate for γ -ray detection in the framework of the model proposing that the most compact and the youngest CSOs can efficiently produce GeV radiation via inverse-Compton scattering of the ambient photon fields by the radio lobe non-thermal electrons. Thus, our detection of the source in γ -rays establishes young radio galaxies as a distinct class of extragalactic high-energy emitters and yields a unique insight on the physical conditions in compact radio lobes interacting with the interstellar medium of the host galaxy.« less

Identification of the High-energy Gamma-Ray Source 3FGL J1544.6-1125 as a Transitional Millisecond Pulsar Binary in an Accreting State

NASA Astrophysics Data System (ADS)

Bogdanov, Slavko; Halpern, Jules P.

2015-04-01

We present X-ray, ultraviolet, and optical observations of 1RXS J154439.4-112820, the most probable counterpart of the unassociated Fermi-LAT source 3FGL J1544.6-1125. The optical data reveal rapid variability, which is a feature of accreting systems. The X-rays exhibit large-amplitude variations in the form of fast switching (within ˜10 s) between two distinct flux levels that differ by a factor of ≈10. The detailed optical and X-ray behavior is virtually identical to that seen in the accretion-disk-dominated states of the transitional millisecond pulsar (MSP) binaries PSR J1023+0038 and XSS J12270-4859, which are also associated with γ-ray sources. Based on the available observational evidence, we conclude that 1RXS J154439.4-112820 and 3FGL J1544.6-1125 are the same object, with the X-rays arising from intermittent low-luminosity accretion onto an MSP and the γ-rays originating from an accretion-driven outflow. 1RXS J154439.4-112820 is only the fourth γ-ray-emitting low-mass X-ray binary system to be identified and is likely to sporadically undergo transformations to a non-accreting rotation-powered pulsar system.

Fermi-LAT detection of a gamma-ray flaring source in the vicinity of PKS 0507+17

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2013-04-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with PKS 0507+17 (also known as 2FGL J0509.9+1802, Nolan et al. 2012, ApJS, 199, 31; R.A.= 05h10m02.3691s, Dec.= +18d00m41.582s, J2000.0, Johnston et al. 1995, AJ, 110, 880), a flat spectrum radio quasar at redshift z = 0.416 (Perlman et al.

The Third Fermi LAT Catalog of High-Energy Gamma-ray Sources

NASA Astrophysics Data System (ADS)

Thompson, David J.; Ballet, J.; Burnett, T.; Fermi Large Area Telescope Collaboration

2014-01-01

The Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) has been gathering science data since August 2008, surveying the full sky every three hours. The second source catalog (2FGL, Nolan et al 2012, ApJS 199, 31) was based on 2 years of data. We are preparing a third source catalog (3FGL) based on 4 years of reprocessed data. The reprocessing introduced a more accurate description of the instrument, which resulted in a narrower point spread function. Both the localization and the detection threshold for hard-spectrum sources have been improved. The new catalog also relies on a refined model of Galactic diffuse emission, particularly important for low-latitude soft-spectrum sources. The process for associating LAT sources with those at other wavelengths has also improved, thanks to dedicated multiwavelength follow-up, new surveys and better ways to extract sources likely to be gamma-ray counterparts. We describe the construction of this new catalog, its characteristics, and its remaining limitations.

The Third Fermi-LAT Catalog of High-Energy Gamma-ray Sources

NASA Astrophysics Data System (ADS)

Burnett, Toby

2014-03-01

The Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) has been gathering science data since August 2008, surveying the full sky every three hours. The second source catalog (2FGL, Nolan et al. 2012, ApJS 199, 31) was based on 2 years of data. We are preparing a third source catalog (3FGL) based on 4 years of reprocessed data. The reprocessing introduced a more accurate description of the instrument, which resulted in a narrower point spread function. Both the localization and the detection threshold for hard-spectrum sources have been improved. The new catalog also relies on a refined model of Galactic diffuse emission, particularly important for low-latitude soft-spectrum sources. The process for associating LAT sources with those at other wavelengths has also improved, thanks to dedicated multiwavelength follow-up, new surveys and better ways to extract sources likely to be gamma-ray counterparts. We describe the construction of this new catalog, its characteristics, and its remaining limitations.

IDENTIFICATION OF THE HIGH-ENERGY GAMMA-RAY SOURCE 3FGL J1544.6–1125 AS A TRANSITIONAL MILLISECOND PULSAR BINARY IN AN ACCRETING STATE

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

Bogdanov, Slavko; Halpern, Jules P.

We present X-ray, ultraviolet, and optical observations of 1RXS J154439.4–112820, the most probable counterpart of the unassociated Fermi-LAT source 3FGL J1544.6–1125. The optical data reveal rapid variability, which is a feature of accreting systems. The X-rays exhibit large-amplitude variations in the form of fast switching (within ∼10 s) between two distinct flux levels that differ by a factor of ≈10. The detailed optical and X-ray behavior is virtually identical to that seen in the accretion-disk-dominated states of the transitional millisecond pulsar (MSP) binaries PSR J1023+0038 and XSS J12270–4859, which are also associated with γ-ray sources. Based on the available observationalmore » evidence, we conclude that 1RXS J154439.4–112820 and 3FGL J1544.6–1125 are the same object, with the X-rays arising from intermittent low-luminosity accretion onto an MSP and the γ-rays originating from an accretion-driven outflow. 1RXS J154439.4–112820 is only the fourth γ-ray-emitting low-mass X-ray binary system to be identified and is likely to sporadically undergo transformations to a non-accreting rotation-powered pulsar system.« less

Fermi LAT detection of renewed and strong GeV gamma-ray flares from blazars PKS 0903-57 and PKS 0346-27

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2018-05-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed high-level gamma-ray activity from sources positionally consistent with the active galaxy PKS 0903-57 (also known as MRC 0903-573 and 3FGL J0904.8-5734, Acero et al. 2015, ApJS, 218, 23) and with the flat spectrum radio quasar PKS 0346-27 (also known as OE -278, TXS 0346-279, MRC 0346-279 and 3FGL J0348.6-2748).

The FGL2/fibroleukin prothrombinase is involved in alveolar macrophage activation in COPD through the MAPK pathway

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

Liu, Yanling; Xu, Sanpeng; Xiao, Fei

2010-05-28

Fibrinogen-like protein 2 (FGL2)/fibroleukin has been reported to play a vital role in the pathogenesis of some critical inflammatory diseases by possessing immunomodulatory activity through the mediation of 'immune coagulation' and the regulation of maturation and proliferation of immune cells. We observed upregulated FGL2 expression in alveolar macrophages from peripheral lungs of chronic obstructive pulmonary disease (COPD) patients and found a correlation between FGL2 expression and increased macrophage activation markers (CD11b and CD14). The role of FGL2 in the activation of macrophages was confirmed by the detection of significantly decreased macrophage activation marker (CD11b, CD11c, and CD71) expression as wellmore » as the inhibition of cell migration and inflammatory cytokine (IL-8 and MMP-9) production in an LPS-induced FGL2 knockdown human monocytic leukemia cell line (THP-1). Increased FGL2 expression co-localized with upregulated phosphorylated p38 mitogen-activated protein kinase (p38-MAPK) in the lung tissues from COPD patients. Moreover, FGL2 knockdown in THP-1 cells significantly downregulated LPS-induced phosphorylation of p38-MAPK while upregulating phosphorylation of c-Jun N-terminal kinase (JNK). Thus, we demonstrate that FGL2 plays an important role in macrophage activation in the lungs of COPD patients through MAPK pathway modulation.« less

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

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Carpen, Bryce

2017-01-01

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 3FGL J1048.4+7144, Acero et al. 2015, ApJS 218, 23) with radio coordinates R.A: 10h48m27.6199s, Dec: +71d43m35.938s (J2000; Johnston et al. 1995, AJ, 110, 880) and redshift z=1.15 (Polatidis et al. 1995, ApJS, 98, 1). Preliminary results indicate that S5 1044+71 showed a marked increase in activity on 2016 December 29, with a daily flux (E > 100 MeV) of (1.1+/-0.2) x10^-6 ph cm^-2 s^-1 (errors are statistical only) which is a factor of about 16 greater than the average flux reported in the third Fermi LAT catalog (3FGL).

Interstellar medium around supernova remnants associated with gamma-ray sources

NASA Astrophysics Data System (ADS)

Duvidovich, L.; Petriella, A.; Giacani, E.; Dubner, G.

2017-07-01

Supernova remnants (SNRs) are potential sources of gamma-rays, either through inverse Compton scattering of electrons off ambient photons or through the decay of neutral pions created by the collision of energetic protons with dense ambient gas. The SNRs G298.6-0.0 and G298.5-0.3 are proposed to be associated to the gamma-ray sources 3FGL J1214.0-6236 and 3FGL J1212.2-6251, respectively. They are located in a complex portion of the Galactic plane, also containing sources of powerful stellar winds such as the star Wolf Rayet HD104994 and the HII regions G298.559-00.114, G298.868-00.432 and G298.228-00.331 with ongoing star formation. We present a study of the neutral hydrogen distribution towards the mentioned SNRs. We found a structure with ellipsoidal morphology that encloses a region containing G298.5-0.3, G298.6-0.0, HD104994, G298.559-00.114 and G298.228-00.331. This HI feature is detected in the velocity range 89-100 km s-1. We propose that the neutral gas would be the accelerated portion (which would explain its high radial velocity) of a gas shell swept up by a series of expansive and explosive events. The rest of this shell (at radial velocities compatible with the systemic velocity of the objects) is not visible because of confusion with galactic emission. We also inspected the distribution of the 12CO gas and found a dense molecular cloud at the systemic velocity of ˜ 22 km s-1 corresponding to the kinematical distance of ˜ 10.4 kpc, compatible with the distance to the SNR G298.6-0.0. This molecular cloud is in spatial coincidence, projected in the sky plane, with the very high energy source associated with the remnant. This fact, suggesting a possible hadronic origin for the gamma-rays emission. Regarding to the SNR G298.5-0.3, smaller and fainter than the previous one, the angular resolution of the molecular data is insufficient to draw meaningful conclusions.

Fermi LAT detection of renewed gamma-ray activity from the FSRQ PKS 2326-502

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Torresi, E.

2012-06-01

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an increasing gamma-ray flux from a source positionally consistent with the Flat Spectrum Radio Quasar PKS 2326-502 (also known as 2FGL J2329.2-4956, Nolan et al. 2012, ApJS, 199, 31; R.A.=23:29:20.880 Dec.=-49:55:40.68, J2000.0, Costa and Loyola 1996, A&AS, 115, 75) at redshift z=0.518 (Jauncey et al. 1984, ApJ, 286, 498).

Fermi LAT detection of a GeV flare from the BL Lac object Mrk 421

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2012-07-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object Mrk 421 (also known as 2FGL J1104.4+3812, Nolan et al. 2012, ApJS, 199, 31; R.A.= 11h04m27.3139s, Dec.= +38d12m31.799s, J2000.0, Fey et al. 2004, AJ, 127, 3587) at redshift z=0.03 (De Vaucouleurs et al.

Increased Gamma-ray Activity from the FSRQ PKS 1424-41

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Dutka, Michael

2012-10-01

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope has observed increased gamma-ray emission from a source positionally coincident with the flat spectrum radio quasar PKS 1424-41 (1424-418; 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31). PKS 1424-41 has the coordinates RA=14h27m56.3s, DEC= -42d06'19.4", J2000, (Johnston et al. 1995, AJ, 110, 880).

Fermi LAT detection of GeV flares from blazars PKS 0458-02 and B2 1144+40

NASA Astrophysics Data System (ADS)

Antolini, Elisa; Buson, Sara

2014-03-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from two sources positionally consistent with the flat spectrum radio quasars PKS 0458-02 (also known as 2FGL J0501.2-0155, Nolan et al. 2012 ApJS, 199, 31) and B2 1144+40 (also known as S4 1144+40 and 2FGL J1146.9+4000). PKS 0458-02 has the radio coordinates RA=05h01m12.8098s, Dec=-1d59m14.255s (J2000, Johnston et al.

Confirming the gamma-ray blazar nature of the low energy counterpart QSO PKS1725+123 of 2FGL J1727.9+1220 with WISE

NASA Astrophysics Data System (ADS)

Massaro, F.; Paggi, A.; D'Abrusco, R.

2012-06-01

Following the near infrared NIR brightening of the QSO PKS1725+123 (=BZQJ1728+1215) (ATEL #4201), associated to the gamma-ray source 2FGL J1727.9+1220 in Nolan et al. (2012 ApJS, 199, 31), we searched in the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010 AJ, 140, 1868) catalog at the VLBI position of the QSO PKS1725+123 (R.A.(J2000): 17h28m07.0512s, Dec.(J2000): +12d15m39.485s) reported in Beasley et al.

The Neural Cell Adhesion Molecule-Derived (NCAM)-Peptide FG Loop (FGL) Mobilizes Endogenous Neural Stem Cells and Promotes Endogenous Regenerative Capacity after Stroke.

PubMed

Klein, Rebecca; Mahlberg, Nicolas; Ohren, Maurice; Ladwig, Anne; Neumaier, Bernd; Graf, Rudolf; Hoehn, Mathias; Albrechtsen, Morten; Rees, Stephen; Fink, Gereon Rudolf; Rueger, Maria Adele; Schroeter, Michael

2016-12-01

The neural cell adhesion molecule (NCAM)-derived peptide FG loop (FGL) modulates synaptogenesis, neurogenesis, and stem cell proliferation, enhances cognitive capacities, and conveys neuroprotection after stroke. Here we investigated the effect of subcutaneously injected FGL on cellular compartments affected by degeneration and regeneration after stroke due to middle cerebral artery occlusion (MCAO), namely endogenous neural stem cells (NSC), oligodendrocytes, and microglia. In addition to immunohistochemistry, we used non-invasive positron emission tomography (PET) imaging with the tracer [ 18 F]-fluoro-L-thymidine ([ 18 F]FLT) to visualize endogenous NSC in vivo. FGL significantly increased endogenous NSC mobilization in the neurogenic niches as evidenced by in vivo and ex vivo methods, and it induced remyelination. Moreover, FGL affected neuroinflammation. Extending previous in vitro results, our data show that the NCAM mimetic peptide FGL mobilizes endogenous NSC after focal ischemia and enhances regeneration by amplifying remyelination and modulating neuroinflammation via affecting microglia. Results suggest FGL as a promising candidate to promote recovery after stroke.

Swift detection of increased X-ray activity from gamma-ray flaring blazar PKS 1424-41

NASA Astrophysics Data System (ADS)

Ciprini, Stefano; Cutini, Sara

2013-01-01

Following enduring gamma-ray flaring activity of the flat spectrum radio quasar PKS 1424-41 (also known as 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31) detected by Fermi LAT during January 2013, two Swift target of opportunity observations were performed on January 24 and 27, 2013. Recent gamma-ray and X-ray flaring activity from the source was observed on January 6 and January 7 (ATel#4714 and ATel #4717).

Fermi LAT detection of a GeV flare from the gravitationally lensed blazar S3 0218+35

NASA Astrophysics Data System (ADS)

Ciprini, S.

2012-08-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the blazar S3 0218+35 (also known as 2FGL J0221.0+3555, Nolan et al. 2012, ApJS, 199, 31, and B2 0218+35, OD 330, lens B0218+357) placed at radio coordinates R.A.: 35.27279 deg, Dec: +35.93715 deg.

Fermi LAT detection of increase gamma-ray emission from OJ 248

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 OJ 248 (also known as 2FGL J0830.5+2407, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 127.7170254 deg, Dec: 24.1832836 deg (J2000, Johnston et al. 1995, AJ, 110, 880) at redshift z=0.94 (Hewitt & Burbidge 1993, ApJS, 87, 451).

Fermi LAT detection of increased gamma-ray activity from the blazar TXS 1318+225

NASA Astrophysics Data System (ADS)

Torresi, E.; D'Ammando, F.; Tanaka, Y.

2012-11-01

The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, has observed an increase in the gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar TXS 1318+225 (z=0.943, Sowards-Emmerd et al. 2003, ApJ, 590, 109; RA=200.2966771 deg, Dec=22.2700300 deg, J2000), also known as 2FGL J1321.1+2215 (Nolan et al. 2012, ApJS, 199, 31).

Photometric Redshifts of High-z BL Lacs from 3FGL Catalog

NASA Astrophysics Data System (ADS)

Kaur, A.; Rau, Arne; Ajello, Marco; Paliya, Vaidehi; Hartmann, Dieter; Greiner, Jochen; Bolmer, Jan; Schady, Patricia

2017-08-01

Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broad-band filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESO's La Silla Observatory. The wavelength range covered by these 13 filters extends from far ultraviolet to the near-Infrared. We report results on 40 new Fermi detected BL Lacs with the photometric redshifts determinations for 5 sources, with 3FGL J1918.2-4110 being the most distance in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the Gamma-ray horizon due to the extragalactic background light.

Discovery of variable VHE γ-ray emission from the binary system 1FGL J1018.6-5856

NASA Astrophysics Data System (ADS)

H. E. S. S. Collaboration; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E. O.; Backes, M.; Balzer, A.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Birsin, E.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Carr, J.; Casanova, S.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Grudzińska, M.; Hadasch, D.; Häffner, S.; Hahn, J.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Lui, R.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niemiec, J.; Oakes, L.; Odaka, H.; Öttl, S.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Arribas, M. Paz; Pekeur, N. W.; Pelletier, G.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reichardt, I.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seyffert, A. S.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van der Walt, J.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Żywucka, N.

2015-05-01

Re-observations with the HESS telescope array of the very high-energy (VHE) source HESS J1018-589 A that is coincident with the Fermi-LAT γ-ray binary 1FGL J1018.6-5856 have resulted in a source detection significance of more than 9σ and the detection of variability (χ2/ν of 238.3/155) in the emitted γ-ray flux. This variability confirms the association of HESS J1018-589 A with the high-energy γ-ray binary detected by Fermi-LAT and also confirms the point-like source as a new VHE binary system. The spectrum of HESS J1018-589 A is best fit with a power-law function with photon index Γ = 2.20 ± 0.14stat ± 0.2sys. Emission is detected up to ~20 TeV. The mean differential flux level is (2.9 ± 0.4) × 10-13 TeV-1 cm-2 s-1 at 1 TeV, equivalent to ~1% of the flux from the Crab Nebula at the same energy. Variability is clearly detected in the night-by-night light curve. When folded on the orbital period of 16.58 days, the rebinned light curve peaks in phase with the observed X-ray and high-energy phaseograms. The fit of the HESS phaseogram to a constant flux provides evidence of periodicity at the level of Nσ> 3σ. The shape of the VHE phaseogram and measured spectrum suggest a low-inclination, low-eccentricity system with amodest impact from VHE γ-ray absorption due to pair production (τ ≲ 1 at 300 GeV).

The neural cell adhesion molecule-derived peptide, FGL, attenuates lipopolysaccharide-induced changes in glia in a CD200-dependent manner.

PubMed

Cox, F F; Berezin, V; Bock, E; Lynch, M A

2013-04-03

Fibroblast growth loop (FGL) is a neural cell adhesion molecule (NCAM)-mimetic peptide that mimics the interaction of NCAM with fibroblast growth factor receptor (FGFR). FGL increases neurite outgrowth and promotes neuronal survival in vitro, and it has also been shown to have neuroprotective effects in vivo. More recent evidence has indicated that FGL has anti-inflammatory effects, decreasing age-related changes in microglial activation and production of inflammatory cytokines. These changes have been associated with an FGL-induced increase in expression of the glycoprotein, CD200, which interacts with its receptor to help maintain microglia in a quiescent state. However whether the FGL-induced anti-inflammatory effects are CD200-dependent has not been examined. The objective of this study was to address this question. Mixed glia were prepared from brain tissue of neonatal wildtype and CD200-deficient mice and preincubated with FGL prior to stimulation with lipopolysaccharide (LPS). Cells were assessed for mRNA expression of markers of microglial activation, CD11b, CD40 and intercellular adhesion molecule 1 (ICAM-1) and also the inflammatory cytokines, interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α, while supernatant concentrations of these cytokine were also assessed. LPS significantly increased all these parameters and the effect was greater in cells prepared from CD200-deficient mice. Whereas FGL attenuated the LPS-induced changes in cells from wildtype mice, it did not do so in cells from CD200-deficient mice. We conclude that the FGL-induced changes in microglial activation are CD200-dependent and demonstrate that the interaction of astrocytes with microglia is critically important for modulating microglial activation. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Fibrinogen-like protein 1, a hepatocyte derived protein is an acute phase reactant

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

Liu Zhilin; Ukomadu, Chinweike

2008-01-25

Fibrinogen-like protein 1 (FGL1) is a hepatocyte derived protein that is upregulated in regenerating rodent livers following partial hepatectomy. It has been implicated as a mitogen for liver cell proliferation. In this study, we show that recombinant human IL-6 induces FGL1 expression in Hep G2 cells in a pattern similar to those of acute phase reactants. Following induction of acute inflammation in rats by subcutaneous injection of turpentine oil, serum FGL1 levels are also enhanced. Although, a recent report suggests that FGL1 associates almost exclusively with the fibrin matrix, we report here that approximately 20% of the total plasma FGL1more » remains free. The enhancement of FGL1 levels in vitro by IL-6 and its induction after turpentine oil injection suggest that it is an acute phase reactant. Its presence in bound and free forms in the blood also implies biological roles that extend beyond the proposed autocrine effect it has on hepatocytes during regeneration.« less

VizieR Online Data Catalog: 2FGL sources observed between 5-9GHz (Schinzel+, 2015)

NASA Astrophysics Data System (ADS)

Schinzel, F. K.; Petrov, L.; Taylor, G. B.; Mahony, E. K.; Edwards, P. G.; Kovalev, Yu. Y.

2015-04-01

A list of 216 target fields were observed with the Very Large Array (VLA). The instantaneous bandwidth was split into two parts, with one half centered at 5.0GHz (4.5-5.5GHz) and the other centered at 7.3GHz (6.8-7.8GHz); on 2012 October 26 and 2012 November 3. See section 2.1 During the first campaign with the Australia Telescope Compact Array (ATCA), from 2012 September 19-20, we observed 411 2FGL unassociated sources in a decl. range of [-90°, +10°] at 5.5 and 9GHz. The details of that observing campaign and results have been reported by Petrov et al. (2013, J/MNRAS/432/1294). We detected a total of 424 point sources. In a second ATCA campaign on 2013 September 25-28, we re-observed sources that were detected at 5GHz, but were not detected at 9GHz. See section 2.2. Follow-up observations of 149 targets selected from the VLA and ATCA survey above -30° decl. were conducted with the Very Long Baseline Array (VLBA) between 2013 Feb-Aug (VCS7 project; 4.128-4.608 and 7.392-7.872GHz simultaneously) and in 2013 Jun-Dec (campaign S5272; 7.392-7.872GHz only). See section 2.3. For sources with decl. below -30° we added 21 objects to the on-going LCS campaign (Petrov et al. 2011, J/MNRAS/414/2528) in 2013 Mar-2013 Jun at 8.200-8.520GHz. See section 2.4. (7 data files).

PSR J1906+0722: an Elusive Gamma-Ray Pulsar

DOE PAGES

Clark, C. J.; Pletsch, H. J.; Wu, J.; ...

2015-08-04

Here, we report the discovery of PSR J1906+0722, a gamma-ray pulsar detected as part of a blind survey of unidentified Fermi Large Area Telescope (LAT) sources being carried out on the volunteer distributed computing system, Einstein@Home. This newly discovered pulsar previously appeared as the most significant remaining unidentified gamma-ray source without a known association in the second Fermi-LAT source catalog (2FGL) and was among the top 10 most significant unassociated sources in the recent third catalog (3FGL). PSR J1906+0722 is a young, energetic, isolated pulsar, with a spin frequency of 8.9 Hz, a characteristic age of 49 kyr, and spin-down powermore » $$1.0\\times {10}^{36}$$ erg s -1. In 2009 August it suffered one of the largest glitches detected from a gamma-ray pulsar ($${\\rm{\\Delta }}f/f\\approx 4.5\\times {10}^{-6}$$). Remaining undetected in dedicated radio follow-up observations, the pulsar is likely radio-quiet. An off-pulse analysis of the gamma-ray flux from the location of PSR J1906+0722 revealed the presence of an additional nearby source, which may be emission from the interaction between a neighboring supernova remnant and a molecular cloud. We discuss possible effects which may have hindered the detection of PSR J1906+0722 in previous searches and describe the methods by which these effects were mitigated in this survey. Lastly, we also demonstrate the use of advanced timing methods for estimating the positional, spin and glitch parameters of difficult-to-time pulsars such as this.« less

PSR J1906+0722: An Elusive Gamma-Ray Pulsar

NASA Astrophysics Data System (ADS)

Clark, C. J.; Pletsch, H. J.; Wu, J.; Guillemot, L.; Ackermann, M.; Allen, B.; de Angelis, A.; Aulbert, C.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bock, O.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Champion, D. J.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cuéllar, A.; Cutini, S.; D'Ammando, F.; Desiante, R.; Drell, P. S.; Eggenstein, H. B.; Favuzzi, C.; Fehrmann, H.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Hou, X.; Jogler, T.; Johnson, A. S.; Jóhannesson, G.; Kramer, M.; Krauss, F.; Kuss, M.; Laffon, H.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Machenschalk, B.; Manfreda, A.; Marelli, M.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohsugi, T.; Orienti, M.; Orlando, E.; de Palma, F.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Saz Parkinson, P. M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torne, P.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, K. S.; Wood, M.; Yassine, M.

2015-08-01

We report the discovery of PSR J1906+0722, a gamma-ray pulsar detected as part of a blind survey of unidentified Fermi Large Area Telescope (LAT) sources being carried out on the volunteer distributed computing system, Einstein@Home. This newly discovered pulsar previously appeared as the most significant remaining unidentified gamma-ray source without a known association in the second Fermi-LAT source catalog (2FGL) and was among the top 10 most significant unassociated sources in the recent third catalog (3FGL). PSR J1906+0722 is a young, energetic, isolated pulsar, with a spin frequency of 8.9 Hz, a characteristic age of 49 kyr, and spin-down power 1.0× {10}36 erg s-1. In 2009 August it suffered one of the largest glitches detected from a gamma-ray pulsar ({{Δ }}f/f≈ 4.5× {10}-6). Remaining undetected in dedicated radio follow-up observations, the pulsar is likely radio-quiet. An off-pulse analysis of the gamma-ray flux from the location of PSR J1906+0722 revealed the presence of an additional nearby source, which may be emission from the interaction between a neighboring supernova remnant and a molecular cloud. We discuss possible effects which may have hindered the detection of PSR J1906+0722 in previous searches and describe the methods by which these effects were mitigated in this survey. We also demonstrate the use of advanced timing methods for estimating the positional, spin and glitch parameters of difficult-to-time pulsars such as this.

Differences in anthropometric characteristics in relation to throwing velocity and competitive level in professional male team handball: a tool for talent profiling.

PubMed

Fieseler, Georg; Hermassi, Souhail; Hoffmeyer, Birgit; Schulze, Stephan; Irlenbusch, Lars; Bartels, Thomas; Delank, Karl-Stefan; Laudner, Kevin G; Schwesig, René

2017-01-01

The primary aim of the study was to examine the anthropometric characteristics as well as throwing and sprinting performance of professional handball players classified by playing position and competition level. 21 male players (age: 25.2±5.1 years) from the first German handball league (FGL) and 34 male players (age: 26.1±4.1 years) from the third German handball league (TGL) were categorized as backs, pivots, wings and goalkeepers. Measurements included anthropometric data (height, mass and body mass index (BMI)), throwing and sprinting performance selected out of a complex handball test (HBCT), which was conducted twice (2 rounds). During the HBCT, the subjects performed two sprints (10, 20 m), two standing throws with run-up (ST) and four vertical jump throws (VJT) over a hurdle (20 cm) with and without precision for goal shot. The anthropometric data revealed a significantly (P=0.038 and η2=0.079) shorter body height for TGL than for FGL players. In the cohort of first league athletes the pivots were the tallest (1.98±0.04 m), backs in the third league showed the maximum body height (1.90±0.05 m). Regarding body mass, pivots were the heaviest players independent from the league membership. The FGL players showed a significantly (P<0.05 and η2>0.10) higher throwing velocity in all type of throws. Body height was significantly related to ST (r=0.53) and VJT (r=0.52) in the first round of HBCT but only for the FGL athletes. Throwing velocity was also correlated with BMI (r=-0.50) among the TGL players. Substantial differences of body characteristics, throwing and sprinting performance between playing positions and competitive levels underline the importance of a careful scouting and position-specific training for professional handball players.

The anti-obesity effects of the dietary combination of fermented red ginseng with levan in high fat diet mouse model.

PubMed

Oh, Jin sun; Lee, Seung Ri; Hwang, Keum Taek; Ji, Geun Eog

2014-04-01

In this study, to evaluate the anti-obesity effects of fermented red ginseng (FG), levan (L), and their combination (FGL), we investigated their effects on the weights of body, liver and white adipose tissue, lipid profiles, and biomarkers for insulin resistance in high fat diet (HFD)-induced obese C57BL/6J male mice. Furthermore, the levels of leptin in the serum were measured. FG (150 mg/kg/d), L (100 mg/kg/d), and FGL (150 mg/kg/d of FG plus 100 mg/kg/d of L) were administered orally to mice daily for 11 weeks. After 11 weeks feeding, FGL showed significantly lower body weight and fat mass with decreasing food efficiency ratio than the HFD control mice. In addition, the FGL group was significantly lower in the levels of total cholesterol and fasting blood glucose and score of the homeostatic model assessment of insulin resistance. Furthermore, FGL decreased serum leptin levels compared to the HFD control group. Taken together, FGL showed a significant anti-obesity effect in HFD-induced obese mice and prevent insulin and leptin resistance. FGL may be potentially useful for the prevention of obesity. Copyright © 2013 John Wiley & Sons, Ltd.

Deletion of Fibrinogen-like Protein 2 (FGL-2), a Novel CD4+ CD25+ Treg Effector Molecule, Leads to Improved Control of Echinococcus multilocularis Infection in Mice

PubMed Central

Wang, Junhua; Vuitton, Dominique A.; Müller, Norbert; Hemphill, Andrew; Spiliotis, Markus; Blagosklonov, Oleg; Grandgirard, Denis; Leib, Stephen L.; Shalev, Itay; Levy, Gary; Lu, Xiaomei; Lin, Renyong; Wen, Hao; Gottstein, Bruno

2015-01-01

Background The growth potential of the tumor-like Echinococcus multilocularis metacestode (causing alveolar echinococcosis, AE) is directly linked to the nature/function of the periparasitic host immune-mediated processes. We previously showed that Fibrinogen-like-protein 2 (FGL2), a novel CD4+CD25+ Treg effector molecule, was over-expressed in the liver of mice experimentally infected with E. multilocularis. However, little is known about its contribution to the control of this chronic helminth infection. Methods/Findings Key parameters for infection outcome in E. multilocularis-infected fgl2-/- (AE-fgl2-/-) and wild type (AE-WT) mice at 1 and 4 month(s) post-infection were (i) parasite load (i. e. wet weight of parasitic metacestode tissue), and (ii) parasite cell proliferation as assessed by determining E. multilocularis 14-3-3 gene expression levels. Serum FGL2 levels were measured by ELISA. Spleen cells cultured with ConA for 48h or with E. multilocularis Vesicle Fluid (VF) for 96h were analyzed ex-vivo and in-vitro. In addition, spleen cells from non-infected WT mice were cultured with rFGL2/anti-FGL2 or rIL-17A/anti-IL-17A for further functional studies. For Treg-immune-suppression-assays, purified CD4+CD25+ Treg suspensions were incubated with CD4+ effector T cells in the presence of ConA and irradiated spleen cells as APCs. Flow cytometry and qRT-PCR were used to assess Treg, Th17-, Th1-, Th2-type immune responses and maturation of dendritic cells. We showed that AE-fgl2-/- mice exhibited (as compared to AE-WT-animals) (a) a significantly lower parasite load with reduced proliferation activity, (b) an increased T cell proliferative response to ConA, (c) reduced Treg numbers and function, and (d) a persistent capacity of Th1 polarization and DC maturation. Conclusions FGL2 appears as one of the key players in immune regulatory processes favoring metacestode survival by promoting Treg cell activity and IL-17A production that contributes to FGL2-regulation. Prospectively, targeting FGL2 could be an option to develop an immunotherapy against AE and other chronic parasitic diseases. PMID:25955764

Fermi-LAT detection of a GeV gamma-ray flare from the blazar PKS 1313-333

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2016-01-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar PKS 1313-333 (also known as TXS 1313-333, OP -322, 2EG J1314-3430 and 3FGL J1316.0-3338), with radio counterpart position R.A.: 199.033275 deg, Dec.: -33.64977 deg, (J2000.0, Johnston et al. 1995, AJ, 110, 880) and with redshift z=1.210 (Jauncey et al. 1982, AJ, 87, 763).

Fermi-LAT detection of increased gamma-ray activity from the FSRQ PKS 1004-217

NASA Astrophysics Data System (ADS)

Kreter, Michael

2018-03-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar (FSRQ) PKS 1004-217 (3FGL J1006.7-2159) with coordinates RA: 10h06m46.4136s, DEC: -21d59m20.410s, J2000 (Beasley et al. 2002, ApJS, 141, 13) and redshift z=0.331 (Hewitt & Burbidge 1989, ApJS, 69, 1). Preliminary analysis indicates that on 4 March 2018, this source was in a high-flux state with a daily averaged gamma-ray flux (E > 100MeV) of (0.84+/-0.08) X 10^-6 photons cm^-2 s^-1 (statistical uncertainties only).

Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

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

Massaro, F.; D'Abrusco, R.; Tosti, G.

2012-04-02

One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified {gamma}-ray sources (UGSs). Despite the large improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one third of the Fermi-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer (WISE) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Basedmore » on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated to the UGS sample of the second Fermi {gamma}-ray catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to {gamma}-ray sources in the 2FGL catalog.« less

UNIDENTIFIED {gamma}-RAY SOURCES: HUNTING {gamma}-RAY BLAZARS

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

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

2012-06-10

One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of unidentified {gamma}-ray sources (UGSs). Despite the major improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one-third of the Fermi-detected objects are still not associated with low-energy counterparts. Recently, using the Wide-field Infrared Survey Explorer survey, we discovered that blazars, the rarest class of active galactic nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, wemore » designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated with the UGS sample of the second Fermi {gamma}-ray LAT catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart to each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated with {gamma}-ray sources in the 2FGL catalog.« less

VizieR Online Data Catalog: Observation of first Fermi-LAT sources at Parkes (Camilo+, 2015)

NASA Astrophysics Data System (ADS)

Camilo, F.; Kerr, M.; Ray, P. S.; Ransom, S. M.; Sarkissian, J.; Cromartie, H. T.; Johnston, S.; Reynolds, J. E.; Wolff, M. T.; Freire, P. C. C.; Bhattacharyya, B.; Ferrara, E. C.; Keith, M.; Michelson, P. F.; Parkinson, P. M. S.; Wood, K. S.

2017-10-01

Keith et al. (2011MNRAS.414.1292K) used a digital filterbank at Parkes to search 11 unidentified sources from the first Fermi-LAT catalog (1FGL; Abdo et al. 2010, J/ApJS/188/405). Two MSPs and one slow pulsar were discovered in single observations of each target at a central frequency of 1.4 GHz. Subsequently, one of these MSPs was found to be associated with the corresponding LAT source. At nearly the same time, in late 2009, we used an analog filterbank at Parkes to search 14 unidentified 1FGL sources (Kerr et al. 2012ApJ...748L...2K). The single observations of these targets resulted in the detection of six MSPs, five of them discoveries. However, confirmation of some of these MSPs was not easy: the search observations lasted for 1-2 hr each, but some of the pulsars were not detected in equivalent initial confirmation attempts, owing to the effects of interstellar scintillation. These and other selection effects (see Section 2.2 for details) led us to search some promising unidentified LAT sources repeatedly. (1 data file).

Entangling quantum-logic gate operated with an ultrabright semiconductor single-photon source.

PubMed

Gazzano, O; Almeida, M P; Nowak, A K; Portalupi, S L; Lemaître, A; Sagnes, I; White, A G; Senellart, P

2013-06-21

We demonstrate the unambiguous entangling operation of a photonic quantum-logic gate driven by an ultrabright solid-state single-photon source. Indistinguishable single photons emitted by a single semiconductor quantum dot in a micropillar optical cavity are used as target and control qubits. For a source brightness of 0.56 photons per pulse, the measured truth table has an overlap with the ideal case of 68.4±0.5%, increasing to 73.0±1.6% for a source brightness of 0.17 photons per pulse. The gate is entangling: At a source brightness of 0.48, the Bell-state fidelity is above the entangling threshold of 50% and reaches 71.0±3.6% for a source brightness of 0.15.

Secreted Fungal Effector Lipase Releases Free Fatty Acids to Inhibit Innate Immunity-Related Callose Formation during Wheat Head Infection[W][OPEN

PubMed Central

Blümke, Antje; Falter, Christian; Herrfurth, Cornelia; Sode, Björn; Bode, Rainer; Schäfer, Wilhelm; Feussner, Ivo; Voigt, Christian A.

2014-01-01

The deposition of the (1,3)-β-glucan cell wall polymer callose at sites of attempted penetration is a common plant defense response to intruding pathogens and part of the plant’s innate immunity. Infection of the Fusarium graminearum disruption mutant Δfgl1, which lacks the effector lipase FGL1, is restricted to inoculated wheat (Triticum aestivum) spikelets, whereas the wild-type strain colonized the whole wheat spike. Our studies here were aimed at analyzing the role of FGL1 in establishing full F. graminearum virulence. Confocal laser-scanning microscopy revealed that the Δfgl1 mutant strongly induced the deposition of spot-like callose patches in vascular bundles of directly inoculated spikelets, while these callose deposits were not observed in infections by the wild type. Elevated concentrations of the polyunsaturated free fatty acids (FFAs) linoleic and α-linolenic acid, which we detected in F. graminearum wild type-infected wheat spike tissue compared with Δfgl1-infected tissue, provided clear evidence for a suggested function of FGL1 in suppressing callose biosynthesis. These FFAs not only inhibited plant callose biosynthesis in vitro and in planta but also partially restored virulence to the Δfgl1 mutant when applied during infection of wheat spikelets. Additional FFA analysis confirmed that the purified effector lipase FGL1 was sufficient to release linoleic and α-linolenic acids from wheat spike tissue. We concluded that these two FFAs have a major function in the suppression of the innate immunity-related callose biosynthesis and, hence, the progress of F. graminearum wheat infection. PMID:24686113

THE HIGH-ENERGY, ARCMINUTE-SCALE GALACTIC CENTER GAMMA-RAY SOURCE

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

Chernyakova, M.; Malyshev, D.; Aharonian, F. A.

2011-01-10

Employing data collected during the first 25 months of observations by the Fermi-LAT, we describe and subsequently seek to model the very high energy (>300 MeV) emission from the central few parsecs of our Galaxy. We analyze the morphological, spectral, and temporal characteristics of the central source, 1FGL J1745.6-2900. The data show a clear, statistically significant signal at energies above 10 GeV, where the Fermi-LAT has angular resolution comparable to that of HESS at TeV energies. This makes a meaningful joint analysis of the data possible. Our analysis of the Fermi data (alone) does not uncover any statistically significant variabilitymore » of 1FGL J1745.6-2900 at GeV energies on the month timescale. Using the combination of Fermi data on 1FGL J1745.6-2900 and HESS data on the coincident, TeV source HESS J1745-290, we show that the spectrum of the central gamma-ray source is inflected with a relatively steep spectral region matching between the flatter spectrum found at both low and high energies. We model the gamma-ray production in the inner 10 pc of the Galaxy and examine cosmic ray (CR) proton propagation scenarios that reproduce the observed spectrum of the central source. We show that a model that instantiates a transition from diffusive propagation of the CR protons at low energy to almost rectilinear propagation at high energies can explain well the spectral phenomenology. We find considerable degeneracy between different parameter choices which will only be broken with the addition of morphological information that gamma-ray telescopes cannot deliver given current angular resolution limits. We argue that a future analysis performed in combination with higher-resolution radio continuum data holds out the promise of breaking this degeneracy.« less

X-ray Follow-ups of XSS J12270-4859: A Low-mass X-ray Binary with Gamma-ray Fermi-LAT Association

NASA Technical Reports Server (NTRS)

deMartino, D.; Belloni, T.; Falanga, M.; Papitto, A.; Motta, S.; Pellizzoni, A.; Evangelista, Y.; Piano, G.; Masetti, N.; Mouchet, M.;

M. Giroletti (INAF-IRA Bologna), M. Orienti (Univ. Bologna, INAF-IRA Bologna), C. C. Cheung (NRL/NRL) on behalf of the Fermi Large Area Telescope Collaboration

NASA Astrophysics Data System (ADS)

Giroletti, M.; Orienti, M.; Cheung, C. C.

2012-09-01

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the blazar S3 0218+35 (also known as 2FGL J0221.0+3555, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 35.27279 deg, Dec: +35.93715 deg (J2000, Patnaik et al. 1992, MNRAS, 254, 655).

Fermi LAT detection of renewed strong GeV activity from the FSRQ 3C 279

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; van Zyl, Pfesesani; Fermi Large Area Telescope Collaboration

2018-04-01

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed an intense and hard gamma-ray flare from a source positionally consistent with the flat spectrum radio quasar 3C 279, also known as 3FGL J1256.1-0547 (Acero et al. 2015, ApJS, 218, 23), with radio coordinates R.A.: 12h56m11.1665s, Dec: -05d47m21.523s (J2000.0; Johnston et al. 1995, AJ, 110, 880).

Realistic estimation for the detectability of dark matter subhalos using Fermi-LAT catalogs

NASA Astrophysics Data System (ADS)

Calore, Francesca; De Romeri, Valentina; Di Mauro, Mattia; Donato, Fiorenza; Marinacci, Federico

2017-09-01

Numerical simulations of structure formation have made remarkable progress in recent years, in particular due to the inclusion of baryonic physics evolving with the dark matter component. We generate Monte Carlo realizations of the dark matter subhalo population based on the results of the recent hydrodynamical simulation suite of Milky Way-sized galaxies [F. Marinacci, R. Pakmor, and V. Springel, Mon. Not. R. Astron. Soc. 437, 1750 (2014)., 10.1093/mnras/stt2003]. We then simulate the gamma-ray sky for both the setup of the 3FGL and 2FHL Fermi Large Area Telescope (LAT) catalogs, including the contribution from the annihilation of dark matter in the subhalos. We find that the flux sensitivity threshold strongly depends on the particle dark matter mass and, more mildly, also on its annihilation channel and the observation latitude. The results differ for the 3FGL and 2FHL catalogs, given their different energy thresholds. We also predict that the number of dark matter subhalos among the unassociated sources is very small. A null number of detectable subhalos in the Fermi-LAT 3FGL catalog would imply upper limits on the dark matter annihilation cross section into b b ¯ of 2 ×10-26(5 ×10-25) cm3 /s with MDM=50 (1000 ) GeV . We find less than one extended subhalo in the Fermi-LAT 3FGL catalog. As a matter of fact, the differences in the spatial and mass distribution of subhalos between hydrodynamic and dark matter-only runs do not have significant impact on the detectability of dark subhalos in gamma rays.

Selection of first-line therapy in multiple sclerosis using risk-benefit decision analysis.

PubMed

Bargiela, David; Bianchi, Matthew T; Westover, M Brandon; Chibnik, Lori B; Healy, Brian C; De Jager, Philip L; Xia, Zongqi

2017-02-14

To integrate long-term measures of disease-modifying drug efficacy and risk to guide selection of first-line treatment of multiple sclerosis. We created a Markov decision model to evaluate disability worsening and progressive multifocal leukoencephalopathy (PML) risk in patients receiving natalizumab (NTZ), fingolimod (FGL), or glatiramer acetate (GA) over 30 years. Leveraging publicly available data, we integrated treatment utility, disability worsening, and risk of PML into quality-adjusted life-years (QALYs). We performed sensitivity analyses varying PML risk, mortality and morbidity, and relative risk of disease worsening across clinically relevant ranges. Over the entire reported range of NTZ-associated PML risk, NTZ as first-line therapy is predicted to provide a greater net benefit (15.06 QALYs) than FGL (13.99 QALYs) or GA (12.71 QALYs) treatment over 30 years, after accounting for loss of QALYs due to PML or death (resulting from all causes). NTZ treatment is associated with delayed worsening to an Expanded Disability Status Scale score ≥6.0 vs FGL or GA (22.7, 17.0, and 12.4 years, respectively). Compared to untreated patients, NTZ-treated patients have a greater relative risk of death in the early years of treatment that varies according to PML risk profile. NTZ as a first-line treatment is associated with the highest net benefit across full ranges of PML risk, mortality, and morbidity compared to FGL or GA. Integrated modeling of long-term treatment risks and benefits informs stratified clinical decision-making and can support patient counseling on selection of first-line treatment options. © 2017 American Academy of Neurology.

VizieR Online Data Catalog: Fermi LAT second source catalog (2FGL) (Nolan+, 2012)

NASA Astrophysics Data System (ADS)

Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Canadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Celik, O.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; Decesar, M. E.; Deklotz, M.; de Luca A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Do Couto, E. Silva E.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Johannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knodlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-God, O. M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Raino, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgro, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; van Etten, A.; van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

2012-06-01

This paper presents a catalog of high-energy γ-ray sources detected, in the 100MeV-100GeV energy range, in the first two years of the Fermi Gamma-ray Space Telescope mission by the Large Area Telescope (LAT), during the period 2008 August 4 (15:43 UTC)-2010 August 1 (01:17 UTC). (4 data files).

SUZAKU X-RAY IMAGING OF THE EXTENDED LOBE IN THE GIANT RADIO GALAXY NGC 6251 ASSOCIATED WITH THE FERMI-LAT SOURCE 2FGL J1629.4+8236

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

Takeuchi, Y.; Kataoka, J.; Takahashi, Y.

2012-04-10

We report the results of a Suzaku X-ray imaging study of NGC 6251, a nearby giant radio galaxy with intermediate FR I/II radio properties. Our pointing direction was centered on the {gamma}-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleus. After subtracting two 'off-source' pointings adjacent to the radio lobe and removing possible contaminants in the X-ray Imaging Spectrometer field of view, we found significant residual X-ray emission most likely diffuse in nature. The spectrum of the excess X-ray emission is wellmore » fitted by a power law with a photon index {Gamma} = 1.90 {+-} 0.15 and a 0.5-8 keV flux of 4 Multiplication-Sign 10{sup -13} erg cm{sup -2} s{sup -1}. We interpret this diffuse X-ray emission component as being due to inverse Compton upscattering of the cosmic microwave background photons by ultrarelativistic electrons within the lobe, with only a minor contribution from the beamed emission of the large-scale jet. Utilizing archival radio data for the source, we demonstrate by means of broadband spectral modeling that the {gamma}-ray flux of the Fermi-LAT source 2FGL J1629.4+8236 may well be accounted for by the high-energy tail of the inverse Compton continuum of the lobe. Thus, this claimed association of {gamma}-rays from the NW lobe of NGC 6251, together with the recent Fermi-LAT imaging of the extended lobes of Centaurus A, indicates that particles may be efficiently (re-)accelerated up to ultrarelativistic energies within extended radio lobes of nearby radio galaxies in general.« less

The Orbit of the Gamma-Ray Binary 1FGL J1018.6−5856

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

Monageng, I. M.; McBride, V. A.; Kniazev, A. Y.

2017-09-20

Gamma-ray binaries are a small subclass of the high mass X-ray binary population that exhibit emission across the whole electromagnetic spectrum. We present the radial velocities of 1FGL J1018.6−5856 based on the observations obtained with the Southern African Large Telescope. We combine our measurements with those published in the literature to get a broad phase coverage. The mass function obtained supports a neutron star compact object, although a black hole mass is possible for the very low inclination angles. The improved phase coverage allows constraints to be placed on the orbital eccentricity ( e = 0.31 ± 0.16), which agreesmore » with the estimates from the high-energy data.« less

Detection of a strong optical and gamma-ray flare from blazar PKS 1424-41

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.; Longo, F.; Jankowsky, F.; Schwemmer, S.; Wagn, S.

2013-01-01

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope has observed an increasing gamma-ray flux from a source positionally coincident with PKS 1424-41 (also known as 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31; R.A.= 14h27m56.2975s, Dec.= -42d06m19.437s, J2000, Johnston et al. 1995, AJ, 110, 880), a flat spectrum radio quasar with a redshift of 1.522 (White et al. 1988, ApJ, 327, 561).

Fermi-LAT detection of a gamma-ray flare from the high-z blazar PKS 2149-306

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2013-01-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with PKS 2149-306 (also known as 2FGL J2151.5-3021, Nolan et al. 2012, ApJS, 199, 31; R.A.= 21h51m55.5239s, Dec.= -30d27m53.697s, J2000.0, Johnston et al. 1995, AJ, 110, 880), a flat spectrum radio quasar at redshift z = 2.345 (Wilkes 1986, MNRAS, 218, 331).

Fermi LAT detection of a new gamma-ray flare from FSRQ PKS 0502+049

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Dutka, Michael

2013-03-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar PKS 0502+049 (also known as 2FGL J0505.5+0501, Nolan et al. 2012 ApJS, 199, 31). PKS 0502+049 has coordinates RA=05h05m23.1847s DEC=+04d59m42.725s, J2000, (Johnston et al. 1995, AJ, 110, 880) and redshift z=0.954 (Drinkwater et al.

AGILE confirmation of gamma-ray activity from the IceCube-170922A error region

NASA Astrophysics Data System (ADS)

Lucarelli, F.; Piano, G.; Pittori, C.; Verrecchia, F.; Tavani, M.; Bulgarelli, A.; Munar-Adrover, P.; Minervini, G.; Ursi, A.; Vercellone, S.; Donnarumma, I.; Fioretti, V.; Zoli, A.; Striani, E.; Cardillo, M.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Pilia, M.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Parmiggiani, N.; Ferrari, A.; Paoletti, F.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

2017-09-01

Following the IceCube observation of a high-energy neutrino candidate event, IceCube-170922A, at T0 = 17/09/22 20:54:30.43 UT (https://gcn.gsfc.nasa.gov/gcn3/21916.gcn3), and the detection of increased gamma-ray activity from a previously known Fermi-LAT gamma-ray source (3FGL J0509.4+0541) in the IceCube-170922A error region (ATel #10791), we have analysed the AGILE-GRID data acquired in the days before and after the neutrino event T0, searching for significant gamma-ray excess above 100 MeV from a position compatible with the IceCube and Fermi-LAT error regions.

Gamma-telescopes Fermi/LAT and GAMMA-400 Trigger Systems Event Recognizing Methods Comparison

NASA Astrophysics Data System (ADS)

Arkhangelskaja, I. V.; Murchenko, A. E.; Chasovikov, E. N.; Arkhangelskiy, A. I.; Kheymits, M. D.

Usually instruments for high-energy γ-quanta registration consists of converter (where γ-quanta produced pairs) and calorimeter for particles energy measurements surrounded by anticoincidence shield used to events identification (whether incident particle was charged or neutral). The influence of pair formation by γ-quanta in shield and the backsplash (moved in the opposite direction particles created due high energy γ-rays interact with calorimeter) should be taken into account. It leads to decrease both effective area and registration efficiency at E>10 GeV. In the presented article the event recognizing methods used in Fermi/LAT trigger system is considered in comparison with the ones applied in counting and triggers signals formation system of gamma-telescope GAMMA-400. The GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the new high-apogee space γ-observatory. The GAMMA-400 consist of converter-tracker based on silicon-strip coordinate detectors interleaved with tungsten foils, imaging calorimeter make of 2 layers of double (x, y) silicon strip coordinate detectors interleaved with planes of CsI(Tl) crystals and the electromagnetic calorimeter CC2 consists only of CsI(Tl) crystals. Several plastics detections systems used as anticoincidence shield, for particles energy and moving direction estimations. The main differences of GAMMA-400 constructions from Fermi/LAT one are using the time-of-flight system with base of 50 cm and double layer structure of plastic detectors provides more effective particles direction definition and backsplash rejection. Also two calorimeters in GAMMA-400 composed the total absorbtion spectrometer with total thickness ∼ 25 X0 or ∼1.2 λ0 for vertical incident particles registration and 54 X0 or 2.5 λ0 for laterally incident ones (where λ0 is nuclear interaction length). It provides energy resolution 1-2% for 10 GeV-3.0×103 GeV events while the Fermi/LAT energy resolution does not reach such a value because of its calorimeter thickness is only ∼10 X0 and energy of registered particles is defined by shower profile analysis. Less than 3% photons will be wrongly recognized as electrons or protons in double-layer ACtop taking into account both temporal and amplitude trigger marker analysis methods during onboard processing in the counting and triggers signals formation system of GAMMA-400. The proton rejection factor will be ∼10-5. The Fermi/LAT based on a 4 × 4 array of identical towers each contains a tracker, calorimeter and data acquisition module. Each tracker consists of 18 x-y silicon-strip layers. The calorimeter in each tower made of eight layers in a hodoscopic arrangement for measure the three-dimensional profiles of showers permits corrections for energy leakage and enhances the capability to discriminate hadronic cosmic rays. The each layer consists of 12 CsI(Tl) based bars. The segmented anticoincidence shield covers the array of towers. Unfortunately, several types of biases lead to systematic effects caused high values of relative systematic uncertainties of the exposure, the number of signal events, the induced fractional signal and so on. For example non confirmed announcement of ∼133 GeV line detection and lost sources in different Fermi catalogues (1FGL, 2FGL, 3FGL) - just well seen in 2FGL Cygnus X-3 (J2032.1+4049) does not appear in 3FGL. It allows to conclude sufficient biases in LAT characteristics obtained methods and event recognized algorithms. Now Fermi/LAT operates during ∼ 7 years but effective caveats methods continuously to be proposed. Respectively, continuation of measurements with use of other telescopes is necessary, and realization of GAMMA-400 will allow improving the results.

Age-related changes in the hippocampus (loss of synaptophysin and glial-synaptic interaction) are modified by systemic treatment with an NCAM-derived peptide, FGL.

PubMed

Ojo, Bunmi; Rezaie, Payam; Gabbott, Paul L; Davies, Heather; Colyer, Frances; Cowley, Thelma R; Lynch, Marina; Stewart, Michael G

2012-07-01

Altered synaptic morphology, progressive loss of synapses and glial (astrocyte and microglial) cell activation are considered as characteristic hallmarks of aging. Recent evidence suggests that there is a concomitant age-related decrease in expression of the presynaptic protein, synaptophysin, and the neuronal glycoprotein CD200, which, by interacting with its receptor, plays a role in maintaining microglia in a quiescent state. These age-related changes may be indicative of reduced neuroglial support of synapses. FG Loop (FGL) peptide synthesized from the second fibronectin type III module of neural cell adhesion molecule (NCAM), has previously been shown to attenuate age-related glial cell activation, and to 'restore' cognitive function in aged rats. The mechanisms by which FGL exerts these neuroprotective effects remain unclear, but could involve regulation of CD200, modifying glial-synaptic interactions (affecting neuroglial 'support' at synapses), or impacting directly on synaptic function. Light and electron microscopic (EM) analyses were undertaken to investigate whether systemic treatment with FGL (i) alters CD200, synaptophysin (presynaptic) and PSD-95 (postsynaptic) immunohistochemical expression levels, (ii) affects synaptic number, or (iii) exerts any effects on glial-synaptic interactions within young (4 month-old) and aged (22 month-old) rat hippocampus. Treatment with FGL attenuated the age-related loss of synaptophysin immunoreactivity (-ir) within CA3 and hilus (with no major effect on PSD-95-ir), and of CD200-ir specifically in the CA3 region. Ultrastructural morphometric analyses showed that FGL treatment (i) prevented age-related loss in astrocyte-synaptic contacts, (ii) reduced microglia-synaptic contacts in the CA3 stratum radiatum, but (iii) had no effect on the mean number of synapses in this region. These data suggest that FGL mediates its neuroprotective effects by regulating glial-synaptic interaction. Copyright © 2011 Elsevier Inc. All rights reserved.

The fibroblast growth factor receptor (FGFR) agonist FGF1 and the neural cell adhesion molecule-derived peptide FGL activate FGFR substrate 2alpha differently.

PubMed

Chen, Yongshuo; Li, Shizhong; Berezin, Vladimir; Bock, Elisabeth

2010-07-01

Activation of fibroblast growth factor (FGF) receptors (FGFRs) both by FGFs and by the neural cell adhesion molecule (NCAM) is crucial in the development and function of the nervous system. We found that FGFR substrate 2alpha (FRS2alpha), Src homologous and collagen A (ShcA), and phospholipase-Cgamma (PLCgamma) were all required for neurite outgrowth from cerebellar granule neurons (CGNs) induced by FGF1 and FGL (an NCAM-derived peptide agonist of FGFR1). Like FGF1, FGL induced tyrosine phosphorylation of FGFR1, FRS2alpha, ShcA, and PLCgamma in a time- and dose-dependent manner. However, the activation of FRS2alpha by FGL was significantly lower than the activation by FGF1, indicating a differential signaling profile induced by NCAM compared with the cognate growth factor.

Fermi-LAT detection of a new gamma-ray flare from the NLSy1 PMN J0948+0022

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2013-01-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with PMN J0948+0022 (also known as 2FGL J0948.8+0020, Nolan et al. 2012, ApJS, 199, 31; R.A.= 09h48m57.3201s, Dec.= +00d22'25.558", J2000, Beasley et al. 2002, ApJS, 141, 13), a radio-loud narrow-line Seyfert 1 at z=0.5846 (Sloan Digital Sky Survey, 2004, SDSS2.C).

Fermi-LAT detection of a GeV flare from the BL Lac object 1ES 2322-409

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2013-10-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the BL Lac object 1ES 2322-409 (also know as 2FGL J2324.7-4042, Nolan et al. 2012, ApJS, 199, 31, and as 1FHL J2324.6-4041, Ackermann et al., ApJS, submitted, arXiv:1306.6772), with 2MASS counterpart coordinates, (J2000.0), R.A.: 351.18612 deg, Dec: -40.68036 deg (Mao 2011, New Ast., 16, 503).

Fermi LAT detection of increased gamma-ray activity from blazar S5 0716+71

NASA Astrophysics Data System (ADS)

Buson, S.

2014-04-01

The Large Area Telescope (LAT), one of two instruments on-board the Fermi Gamma-ray Space Telescope, has observed an increase in gamma-ray activity from a source positionally coincident with the BL Lac object S5 0716+71 (also known as 2FGL J0721.9+7120, Nolan et al. ...

Properties of the redback millisecond pulsar binary 3FGL J0212.1+5320

NASA Astrophysics Data System (ADS)

Shahbaz, T.; Linares, M.; Breton, R. P.

2017-12-01

Linares et al. obtained quasi-simultaneous g΄-, r΄- and i΄-band light curves and an absorption-line radial velocity curve of the secondary star in the redback system 3FGL J0212.1+5320. The light curves showed two maxima and minima primarily due to the secondary star's ellipsoidal modulation, but with unequal maxima and minima. We fit these light curves and radial velocities with our X-ray binary model including either a dark solar-type star spot or a hotspot due to off-centre heating from an intrabinary shock to account for the unequal maxima. Both models give a radial velocity semi-amplitude and rotational broadening that agree with the observations. The observed secondary star's effective temperature is best matched with the value obtained using the hotspot model, which gives a neutron star and secondary star mass of M1 = 1.85 ^{+0.32}_{-0.26} M⊙ and M2 = 0.50 ^{+0.22}_{-0.19} M⊙, respectively.

Fermi LAT detection of enhanced gamma-ray emission from the Crab Nebula region

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Buehler, Rolf; Hays, Elizabeth; Dutka, Michael

2012-07-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed a significant increase in the gamma-ray activity from a source positionally consistent with the Crab Nebula on July 3, 2012. Preliminary LAT analysis indicates that the daily-averaged gamma-ray emission (E >100 MeV) from the direction of the Crab doubled from (2.4 +/- 0.5) x 10^-6 ph/cm2/sec (statistical errors only) on July 2nd to (5.5 +/- 0.7) x 10^-6 ph/cm2/sec on July 3rd, a factor of 2 greater than the average flux of (2.75 +/- 0.10) x 10^-6 ph/cm2/sec reported in the second Fermi LAT catalog (2FGL, Nolan et al.

Short Pulse High Brightness X-ray Production with the PLEIADES Thomson Scattering Source

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

Anderson, S G; Barty, C P J; Betts, S M

2003-07-01

We describe PLEIADES, a compact, tunable, high-brightness, ultra-short pulse, Thomson x-ray source. The peak brightness of the source is expected to exceed 10{sup 20} photons/s/0.1% bandwidth/mm{sup 2}/mrad{sup 2}. Initial results are reported and compared to theoretical calculations.

Enhanced gamma-ray emission from the FSRQ PKS 0131-522

NASA Astrophysics Data System (ADS)

Piano, G.; Pittori, C.; Verrecchia, F.; Minervini, G.; Lucarelli, F.; Munar-Adrover, P.; Ursi, A.; Bulgarelli, A.; Fioretti, V.; Parmiggiani, N.; Tavani, M.; Donnarumma, I.; Vercellone, S.; Striani, E.; Cardillo, M.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Pilia, M.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Ferrari, A.; Paoletti, F.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

2017-11-01

AGILE is detecting enhanced gamma-ray emission above 100 MeV from the FSRQ PKS 0131-522 (z=0.02; also known as 3FGL J0133.2-5159), at Galactic coordinates (l, b) = (288.4, -63.8) +/- 0.6 deg (stat.) +/- 0.1 deg (sys.).

Exploring anti-correlated radio/X-ray modes in transitional millisecond pulsars

NASA Astrophysics Data System (ADS)

Jaodand, Amruta

2017-09-01

Recently, using coordinated VLA+Chandra observations, Bogdanov et al.(2017) have uncovered a stunning anti-correlation in the LMXB state of the tMSP PSR J1023+0038. They see that radio luminosity consistently peaks during the X-ray `low' luminosity modes. Also, we have found a promising candidate tMSP, 3FGL J1544-1125(J1544) (Bogdanov and Halpern 2015; currently only tMSP candidate apart from J1023 in a persistent LMXB state). Using VLA and simultaneous Swift observations we see that it lies on the proposed tMSP track in radio vs. X-ray luminosity (L_ R/L_X) diagram. This finding strengthens its classification as a tMSP and provides an excellent opportunity to a)determine universality of radio/X-ray brightness anti-correlatio and b)understand jet/outflow formation in tMSPs.

Search for Spatially Extended Fermi-LAT Sources Using Two Years of Data

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

Lande, Joshua; Ackermann, Markus; Allafort, Alice

2012-07-13

Spatial extension is an important characteristic for correctly associating {gamma}-ray-emitting sources with their counterparts at other wavelengths and for obtaining an unbiased model of their spectra. We present a new method for quantifying the spatial extension of sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi). We perform a series of Monte Carlo simulations to validate this tool and calculate the LAT threshold for detecting the spatial extension of sources. We then test all sources in the second Fermi -LAT catalog (2FGL) for extension. We report the detection of sevenmore » new spatially extended sources.« less

Astrophysical interpretation of the anisotropies in the unresolved gamma-ray background

NASA Astrophysics Data System (ADS)

Ando, Shin'ichiro; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco; Zechlin, Hannes-S.

2017-06-01

Recently, a new measurement of the auto- and cross-correlation angular power spectrum (APS) of the isotropic gamma-ray background was performed, based on 81 months of data of the Fermi Large-Area Telescope (LAT). Here, we fit, for the first time, the new APS data with a model describing the emission of unresolved blazars. These sources are expected to dominate the anisotropy signal. The model we employ in our analysis reproduces well the blazars resolved by Fermi LAT. When considering the APS obtained by masking the sources listed in the 3FGL catalog, we find that unresolved blazars underproduce the measured APS below ˜1 GeV . Contrary to past results, this suggests the presence of a new contribution to the low-energy APS, with a significance of, at least, 5 σ . The excess can be ascribed to a new class of faint gamma-ray emitters. If we consider the APS obtained by masking the sources in the 2FGL catalog, there is no underproduction of the APS below 1 GeV, but the new source class is still preferred over the blazars-only scenario (with a significance larger than 10 σ ). The properties of the new source class and the level of anisotropies induced in the isotropic gamma-ray background are the same, independent of the APS data used. In particular, the new gamma-ray emitters must have a soft energy spectrum, with a spectral index ranging, approximately, from 2.7 to 3.2. This complicates their interpretation in terms of known sources, since, normally, star-forming and radio galaxies are observed with a harder spectrum. The new source class identified here is also expected to contribute significantly to the intensity of the isotropic gamma-ray background.

The calibration of read-out-streak photometry in the XMM-Newton Optical Monitor and the construction of a bright-source catalogue

NASA Astrophysics Data System (ADS)

Page, M. J.; Chan, N.; Breeveld, A. A.; Talavera, A.; Yershov, V.; Kennedy, T.; Kuin, N. P. M.; Hancock, B.; Smith, P. J.; Carter, M.

2017-04-01

The dynamic range of the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded from its micro-channel-plate (MCP) intensified charge-coupled device (CCD) detector. One way to overcome this limitation is to use photons that arrive during the frame transfer of the CCD, forming vertical read-out streaks for bright sources. We calibrate these read-out streaks for photometry of bright sources observed with XMM-OM. The bright-source limit for read-out-streak photometry is set by the recharge time of the MCPs. For XMM-OM, we find that the MCP recharge time is 5.5 × 10-4 s. We determine that the effective bright limits for read-out-streak photometry with XMM-OM are approximately 1.5 mag brighter than the bright-source limits for normal aperture photometry in full-frame images. This translates into bright-source limits in Vega magnitudes of UVW2=7.1, UVM2=8.0, UVW1=9.4, U=10.5, B=11.5, V=10.2, and White=12.5 for data taken early in the mission. The limits brighten by up to 0.2 mag, depending on filter, over the course of the mission as the detector ages. The method is demonstrated by deriving UVW1 photometry for the symbiotic nova RR Telescopii, and the new photometry is used to constrain the e-folding time of its decaying ultraviolet (UV) emission. Using the read-out-streak method, we obtain photometry for 50 per cent of the missing UV source measurements in version 2.1 of the XMM-Newton Serendipitous UV Source Survey catalogue.

The regulatory T cell effector molecule fibrinogen-like protein 2 is necessary for the development of rapamycin-induced tolerance to fully MHC-mismatched murine cardiac allografts

PubMed Central

Urbanellis, Peter; Shyu, Wendy; Khattar, Ramzi; Wang, Jihong; Zakharova, Anna; He, Wei; Sadozai, Hassan; Amir, Achiya Z; Shalev, Itay; Phillips, M James; Adeyi, Oyedele; Ross, Heather; Grant, David; Levy, Gary A; Chruscinski, Andrzej

2015-01-01

Therapies that promote tolerance in solid organ transplantation will improve patient outcomes by eliminating the need for long-term immunosuppression. To investigate mechanisms of rapamycin-induced tolerance, C3H/HeJ mice were heterotopically transplanted with MHC-mismatched hearts from BALB/cJ mice and were monitored for rejection after a short course of rapamycin treatment. Mice that had received rapamycin developed tolerance with indefinite graft survival, whereas untreated mice all rejected their grafts within 9 days. In vitro, splenic mononuclear cells from tolerant mice maintained primary CD4+ and CD8+ immune responses to donor antigens consistent with a mechanism that involves active suppression of immune responses. Furthermore, infection with lymphocytic choriomeningitis virus strain WE led to loss of tolerance suggesting that tolerance could be overcome by infection. Rapamycin-induced, donor-specific tolerance was associated with an expansion of regulatory T (Treg) cells in both the spleen and allograft and elevated plasma levels of fibrinogen-like protein 2 (FGL2). Depletion of Treg cells with anti-CD25 (PC61) and treatment with anti-FGL2 antibody both prevented tolerance induction. Tolerant allografts were populated with Treg cells that co-expressed FGL2 and FoxP3, whereas rejecting allografts and syngeneic grafts were nearly devoid of dual-staining cells. We examined the utility of an immunoregulatory gene panel to discriminate between tolerance and rejection. We observed that Treg-associated genes (foxp3, lag3, tgf-β and fgl2) had increased expression and pro-inflammatory genes (ifn-γ and gzmb) had decreased expression in tolerant compared with rejecting allografts. Taken together, these data strongly suggest that Treg cells expressing FGL2 mediate rapamycin-induced tolerance. Furthermore, a gene biomarker panel that includes fgl2 can distinguish between rejecting and tolerant grafts. PMID:24990517

Coastal hazards and groundwater salinization on low coral islands.

NASA Astrophysics Data System (ADS)

Terry, James P.; Chui, T. F. May

2016-04-01

Remote oceanic communities living on low-lying coral islands (atolls) without surface water rely for their survival on the continuing viability of fragile groundwater resources. These exist in the form of fresh groundwater lenses (FGLs) that develop naturally within the porous coral sand and gravel substrate. Coastal hazards such as inundation by high-energy waves driven by storms and continuing sea-level rise (SLR) are among many possible threats to viable FGL size and quality on atolls. Yet, not much is known about the combined effects of wave washover during powerful storms and SLR on different sizes of coral island, nor conversely how island size influences lens resilience against damage. This study investigates FGL damage by salinization (and resilience) caused by such coastal hazards using a modelling approach. Numerical modelling is carried out to generate steady-state FGL configurations at three chosen island sizes (400, 600 and 800 m widths). Steady-state solutions reveal how FGL dimensions are related in a non-linear manner to coral island size, such that smaller islands develop much more restricted lenses than larger islands. A 40 cm SLR scenario is then imposed. This is followed by transient simulations to examine storm-induced wave washover and subsequent FGL responses to saline damage over a 1 year period. Smaller FGLs display greater potential for disturbance by SLR, while larger and more robust FGLs tend to show more resilience. Further results produce a somewhat counterintuitive finding: in the post-SLR condition, FGL vulnerability to washover salinization may actually be reduced, owing to the thinner layer of unsaturated substrate lying above the water table into which saline water can infiltrate during a storm event. Nonetheless, combined washover and SLR impacts imply overall that advancing groundwater salinization may lead to some coral islands becoming uninhabitable long before they are completely submerged by sea-level rise, thereby calling into question the sustainability of atoll communities that face recurrent coastal hazards.

Programmed death (PD)-1 attenuates macrophage activation and brain inflammation via regulation of fibrinogen-like protein 2 (Fgl-2) after intracerebral hemorrhage in mice.

PubMed

Yuan, Bangqing; Huang, Shaokuan; Gong, Shuangfeng; Wang, Feihong; Lin, Li; Su, Tonggang; Sheng, Hanchao; Shi, Hui; Ma, Kunlong; Yang, Zhao

2016-11-01

Neuroinflammation plays an important role in the recovery of brain injury in ICH. Macrophage is the major executor in the neuroinflammation and initiates neurological defects. Programmed death 1 (PD-1) delivers inhibitory signals that regulate the balance between T cell activation, tolerance, and immunopathology. PD-1 expression by macrophages plays a pathologic role in the innate inflammatory response. However, the exact role of PD-1 on inflammatory responses following ICH has not been well identified. In this experiment, PD-1 KO (PD-1 -/-) ICH mice and Wild-type (WT) ICH mice were caused by intracranial injection of type IV collagenase. The level of macrophage activation, inflammatory cytokines and fibrinogen-like protein 2 (Fgl-2) were detected using immunofluorescence staining and ELISA assays. In addition, brain edema and neurological scores of ICH mice were also measured. Our data demonstrated that ICH promoted PD-1 expression of macrophage and enhanced inflammatory cytokines and Fgl-2 concentrations. PD-1 -/- mice exhibited significantly higher expression of the inflammatory cytokines which initiate Fgl-2, than did their wild-type (WT) littermates. As a result, macrophage activation, cerebral edema and neurological deficit scores of PD-1 -/- mice were higher. In conclusion, our data demonstrate that PD-1 plays a vital role in brain inflammation via regulation of Fgl-2 after ICH, and that manipulation of PD-1 might be a promising therapeutical target in ICH. Copyright © 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

VizieR Online Data Catalog: Reference Catalogue of Bright Galaxies (RC1; de Vaucouleurs+ 1964)

NASA Astrophysics Data System (ADS)

de Vaucouleurs, G.; de Vaucouleurs, A.

1995-11-01

The Reference Catalogue of Bright Galaxies lists for each entry the following information: NGC number, IC number, or A number; A, B, or C designation; B1950.0 positions, position at 100 year precession; galactic and supergalactic positions; revised morphological type and source; type and color class in Yerkes list 1 and 2; Hubble-Sandage type; revised Hubble type according to Holmberg; logarithm of mean major diameter (log D) and ratio of major to minor diameter (log R) and their weights; logarithm of major diameter; sources of the diameters; David Dunlap Observatory type and luminosity class; Harvard photographic apparent magnitude; weight of V, B-V(0), U-B(0); integrated magnitude B(0) and its weight in the B system; mean surface brightness in magnitude per square minute of arc and sources for the B magnitude; mean B surface brightness derived from corrected Harvard magnitude; the integrated color index in the standard B-V system; "intrinsic" color index; sources of B-V and/or U-B; integrated color in the standard U-B system; observed radial velocity in km/sec; radial velocity corrected for solar motion in km/sec; sources of radial velocities; solar motion correction; and direct photographic source. The catalog was created by concatenating four files side by side. (1 data file).

Fermi LAT detection of a GeV flare from the BL Lac object PKS 2233-148

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2012-06-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object PKS 2233-148 (also known as 2FGL J2236.5-1431, Nolan et al. 2012, ApJS, 199, 31, and OY -156) placed at R.A.: 339.1420296 deg, Dec.: -14.5561633 (J2000, Petrov et al. 2008, AJ, 136, 580). No redshift for the source has been measured up to now, demonstrating the BL Lac object character type of this source.

State diagram of magnetostatic coupling phase-locked spin-torque oscillators

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

Zhang, Mengwei; Wang, Longze; Wei, Dan, E-mail: weidan@mail.tsinghua.edu.cn

2015-05-07

The state diagram of magnetostatic coupling phase-locked spin torque oscillator (STO) with perpendicular reference layer and planar field generation layer (FGL) is studied by the macrospin model and the micromagnetic model. The state diagrams of current densities are calculated under various external fields. The simulation shows that there are two phase-lock current density regions. In the phase-locked STOs in low current region I, the spin configuration of FGL is uniform; in high current region II, the spin configuration of FGL is highly nonuniform. In addition, the results with different STOs separation L{sub s} are compared, and the coupling between twomore » STOs is largely decreased when L{sub s} is increased from 40 nm to 60 nm.« less

INTERFEROMETRIC MONITORING OF GAMMA-RAY BRIGHT AGNs. I. THE RESULTS OF SINGLE-EPOCH MULTIFREQUENCY OBSERVATIONS

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

Lee, Sang-Sung; Wajima, Kiyoaki; Algaba, Juan-Carlos

2016-11-01

We present results of single-epoch very long baseline interferometry (VLBI) observations of gamma-ray bright active galactic nuclei (AGNs) using the Korean VLBI Network (KVN) at the 22, 43, 86, and 129 GHz bands, which are part of a KVN key science program, Interferometric Monitoring of Gamma-Ray Bright AGNs. We selected a total of 34 radio-loud AGNs of which 30 sources are gamma-ray bright AGNs with flux densities of >6 × 10{sup −10} ph cm{sup −2} s{sup −1}. Single-epoch multifrequency VLBI observations of the target sources were conducted during a 24 hr session on 2013 November 19 and 20. All observed sources weremore » detected and imaged at all frequency bands, with or without a frequency phase transfer technique, which enabled the imaging of 12 faint sources at 129 GHz, except for one source. Many of the target sources are resolved on milliarcsecond scales, yielding a core-jet structure, with the VLBI core dominating the synchrotron emission on a milliarcsecond scale. CLEAN flux densities of the target sources are 0.43–28 Jy, 0.32–21 Jy, 0.18–11 Jy, and 0.35–8.0 Jy in the 22, 43, 86, and 129 GHz bands, respectively. Spectra of the target sources become steeper at higher frequency, with spectral index means of −0.40, −0.62, and −1.00 in the 22–43 GHz, 43–86 GHz and 86–129 GHz bands, respectively, implying that the target sources become optically thin at higher frequencies (e.g., 86–129 GHz).« less

The JCMT Transient Survey: Stochastic and Secular Variability of Protostars and Disks In the Submillimeter Region Observed over 18 Months

NASA Astrophysics Data System (ADS)

Johnstone, Doug; Herczeg, Gregory J.; Mairs, Steve; Hatchell, Jennifer; Bower, Geoffrey C.; Kirk, Helen; Lane, James; Bell, Graham S.; Graves, Sarah; Aikawa, Yuri; Chen, Huei-Ru Vivien; Chen, Wen-Ping; Kang, Miju; Kang, Sung-Ju; Lee, Jeong-Eun; Morata, Oscar; Pon, Andy; Scicluna, Peter; Scholz, Aleks; Takahashi, Satoko; Yoo, Hyunju; The JCMT Transient Team

2018-02-01

We analyze results from the first 18 months of monthly submillimeter monitoring of eight star-forming regions in the JCMT Transient Survey. In our search for stochastic variability in 1643 bright peaks, only the previously identified source, EC 53, shows behavior well above the expected measurement uncertainty. Another four sources—two disks and two protostars—show moderately enhanced standard deviations in brightness, as expected for stochastic variables. For the two protostars, this apparent variability is the result of single epochs that are much brighter than the mean. In our search for secular brightness variations that are linear in time, we measure the fractional brightness change per year for 150 bright peaks, 50 of which are protostellar. The ensemble distribution of slopes is well fit by a normal distribution with σ ∼ 0.023. Most sources are not rapidly brightening or fading at submillimeter wavelengths. Comparison against time-randomized realizations shows that the width of the distribution is dominated by the uncertainty in the individual brightness measurements of the sources. A toy model for secular variability reveals that an underlying Gaussian distribution of linear fractional brightness change σ = 0.005 would be unobservable in the present sample, whereas an underlying distribution with σ = 0.02 is ruled out. Five protostellar sources, 10% of the protostellar sample, are found to have robust secular measures deviating from a constant flux. The sensitivity to secular brightness variations will improve significantly with a sample over a longer time duration, with an improvement by factor of two expected by the conclusion of our 36 month survey.

Periodic emission from the gamma-ray binary 1FGL J1018.6-5856.

PubMed

Fermi LAT Collaboration; Ackermann, M; Ajello, M; Ballet, J; Barbiellini, G; Bastieri, D; Belfiore, A; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Cavazzuti, E; Cecchi, C; Çelik, Ö; Charles, E; Chaty, S; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Corbel, S; Corbet, R H D; Cutini, S; de Luca, A; den Hartog, P R; de Palma, F; Dermer, C D; Digel, S W; do Couto e Silva, E; Donato, D; Drell, P S; Drlica-Wagner, A; Dubois, R; Dubus, G; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hill, A B; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, T J; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ozaki, M; Paneque, D; Parent, D; Pesce-Rollins, M; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Ritz, S; Romani, R W; Roth, M; Saz Parkinson, P M; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Tanaka, T; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vianello, G; Vitale, V; Waite, A P; Winer, B L; Wood, K S; Wood, M; Yang, Z; Zimmer, S; Coe, M J; Di Mille, F; Edwards, P G; Filipović, M D; Payne, J L; Stevens, J; Torres, M A P

2012-01-13

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

Periodic Emission from the Gamma-Ray Binary 1FGL J1018.6-5856

NASA Technical Reports Server (NTRS)

2012-01-01

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy, A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL ]1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL ]1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

The Neural Cell Adhesion Molecule-Derived Peptide FGL Facilitates Long-Term Plasticity in the Dentate Gyrus in Vivo

ERIC Educational Resources Information Center

Dallerac, Glenn; Zerwas, Meike; Novikova, Tatiana; Callu, Delphine; Leblanc-Veyrac, Pascale; Bock, Elisabeth; Berezin, Vladimir; Rampon, Claire; Doyere, Valerie

2011-01-01

The neural cell adhesion molecule (NCAM) is known to play a role in developmental and structural processes but also in synaptic plasticity and memory of the adult animal. Recently, FGL, a NCAM mimetic peptide that binds to the Fibroblast Growth Factor Receptor 1 (FGFR-1), has been shown to have a beneficial impact on normal memory functioning, as…

Fermi LAT detection of renewed GeV gamma-ray activity from the gravitationally lensed blazar PKS 1830-211

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2012-06-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with PKS 1830-211 (also known as 2FGL J1833.6-2104, Nolan et al. 2012, ApJS, 199, 31, placed at RA: 18h 33m 39.9s, Dec -21d 03m 40s, J2000, van Ommen et al., 1995, ApJ, 444, 561). PKS 1830-211 (z=2.507, Lovell et al. 1998, ApJ, 508, L51) is a distant and peculiar flat spectrum radio quasar with intervening absorption systems and being subject to gravitational lensing by a galaxy placed at z=0.886 (Wiklind & Combes 1996, Nature, 379, 11).

Einstein@Home Finds an Elusive Pulsar

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2015-08-01

Since the release of the second Fermi-LAT catalog in 2012, astronomers have been hunting for 3FGL J1906.6+0720, a gamma-ray source whose association couldn't be identified. Now, personal-computer time volunteered through the Einstein@Home project has resulted in the discovery of a pulsar that has been hiding from observers for years. A Blind Search: Identifying sources detected by Fermi-LAT can be tricky: the instrument's sky resolution is limited, so the position of the source can be hard to pinpoint. The gamma-ray source 3FGL J1906.6+0720 appeared in both the second and third Fermi-LAT source catalogs, but even after years of searching, no associated radio or X-ray source had been found. A team of researchers, led by Colin Clark of the Max Planck Institute for Gravitational Physics, suspected that the source might be a gamma-ray pulsar. To confirm this, however, they needed to detect pulsed emission — something inherently difficult given the low photon count and the uncertain position of the source. The team conducted a blind search for pulsations coming from the general direction of the gamma-ray source. Two things were needed for this search: clever data analysis and a lot of computing power. The data analysis algorithm was designed to be adaptive: it searched a 4-dimensional parameter space that included a safety margin, allowing the algorithm to wander if the source was at the edge of the parameter space. The computing power was contributed by tens of thousands of personal computers volunteered by participants in the Einstein@Home project, making much shorter work out of a search that would have required dozens of years on a single laptop. The sky region around the newly discovered pulsar. The dotted ellipse shows the 3FGL catalog 95% confidence region for the source. The data analysis algorithm was designed to search an area 50% larger (given by the dashed ellipse), but it was allowed to “walk away” within the gray shaded region if the source seemed to be at the edge. This adaptive flexibility is what allowed the pulsar's actual location — shown by the solid ellipse, inset — to be found. [Clark et al., 2015] Teasing the Signal From Misinformation: This new search method turned out to be exactly what was needed: the team was able to identify pulsed emission coming from a point located significantly outside of the source's original confidence region. This source, now named PSR J1906+0722, has been determined to be a young, energetic, isolated pulsar, and the team was able to identify its spin parameters and pulse history from the last six years. So why was this mysterious pulsar so hard to find? Its misidentified position, most likely due to a secondary source that had been lumped with the pulsar into a single source, was the biggest factor. Additionally, the pulsar had an enormous glitch one year into Fermi observations of it, making it even more difficult to pin down its pulse profile. The team’s success in spite of these complications indicates the value of their methods for identifying other young, gamma-ray, radio-quiet pulsars that are likely hidden in the Fermi-LAT catalog. Citation: C. J. Clark et al. 2015 ApJ, 809, L2. doi:10.1088/2041-8205/809/1/L2

PLEIADES: High Peak Brightness, Subpicosecond Thomson Hard-X-ray source

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

Kuba, J; Anderson, S G; Barty, C J

2003-12-15

The Picosecond Laser-Electron Inter-Action for the Dynamic Evaluation of Structures (PLEIADES) facility, is a unique, novel, tunable (10-200 keV), ultrafast (ps-fs), hard x-ray source that greatly extends the parameter range reached by existing 3rd generation sources, both in terms of x-ray energy range, pulse duration, and peak brightness at high energies. First light was observed at 70 keV early in 2003, and the experimental data agrees with 3D codes developed at LLNL. The x-rays are generated by the interaction of a 50 fs Fourier-transform-limited laser pulse produced by the TW-class FALCON CPA laser and a highly focused, relativistic (20-100 MeV),more » high brightness (1 nC, 0.3-5 ps, 5 mm.mrad, 0.2% energy spread) photo-electron bunch. The resulting x-ray brightness is expected to exceed 10{sup 20} ph/mm{sup 2}/s/mrad{sup 2}/0.1% BW. The beam is well-collimated (10 mrad divergence over the full spectrum, 1 mrad for a single color), and the source is a unique tool for time-resolved dynamic measurements in matter, including high-Z materials.« less

Radio and gamma-ray properties of extragalactic jets from the TANAMI sample

DOE PAGES

Böck, M.; Kadler, M.; Müller, C.; ...

2016-05-04

The TANAMI program has been observing parsec-scale radio jets of southern (declination south of - 30°) γ-ray bright AGN, simultaneously with Fermi/LAT monitoring of their γ-ray emission, via high-resolution radio imaging with Very Long Baseline Interferometry techniques. In this paper, we present the radio and γ-rayproperties of the TANAMI sources based on one year of contemporaneous TANAMI and Fermi/LAT data. A large fraction (72%) of the TANAMI sample can be associated with bright γ-ray sources for this time range. Association rates differ for different optical classes with all BL Lacs, 76% of quasars, and just 17% of galaxies detected bymore » the LAT. Upper limits were established on the γ-ray flux from TANAMI sources not detected by LAT. This analysis led to the identification of three new Fermi sources whose detection was later confirmed. The γ-ray and radio luminosities are related by L γ ∝ L r 0.89±0.04. The brightness temperatures of the radio cores increase with the average γ-ray luminosity and the presence of brightness temperatures above the inverse Compton limit implies strong Doppler boosting in those sources. The undetected sources have lower γ/radio luminosity ratios and lower contemporaneous brightness temperatures. Finally, unless the Fermi/LAT-undetected blazars are much γ-ray-fainter than the Fermi/LAT-detected sources, their γ-ray luminosity should not be significantly lower than the upper limits calculated here.« less

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).

Fermi Gamma-Ray Space Telescope Science Overview

NASA Technical Reports Server (NTRS)

Thompson, David J.

2010-01-01

After more than 2 years of science operations, the Fermi Gamma-ray Space Telescope continues to survey the high-energy sky on a daily basis. In addition to the more than 1400 sources found in the first Fermi Large Area Telescope Catalog (I FGL), new results continue to emerge. Some of these are: (1) Large-scale diffuse emission suggests possible activity from the Galactic Center region in the past; (2) a gamma-ray nova was found, indicating particle acceleration in this binary system; and (3) the Crab Nebula, long thought to be a steady source, has varied in the energy ranges seen by both Fermi instruments.

VizieR Online Data Catalog: FIR data of IR-bright dust-obscured galaxies (DOGs) (Toba+, 2017)

NASA Astrophysics Data System (ADS)

Toba, Y.; Nagao, T.; Wang, W.-H.; Matsuhara, H.; Akiyama, M.; Goto, T.; Koyama, Y.; Ohyama, Y.; Yamamura, I.

2017-11-01

We investigate the star-forming activity of a sample of infrared (IR)-bright dust-obscured galaxies (DOGs) that show an extreme red color in the optical and IR regime, (i-[22])AB>7.0. Combining an IR-bright DOG sample with the flux at 22μm>3.8mJy discovered by Toba & Nagao (2016ApJ...820...46T) with the IRAS faint source catalog version 2 and AKARI far-IR (FIR) all-sky survey bright source catalog version 2, we selected 109 DOGs with FIR data. For a subsample of seven IR-bright DOGs with spectroscopic redshifts (0.07

Far-infrared Properties of Infrared-bright Dust-obscured Galaxies Selected with IRAS and AKARI Far-infrared All-sky Survey

NASA Astrophysics Data System (ADS)

Toba, Yoshiki; Nagao, Tohru; Wang, Wei-Hao; Matsuhara, Hideo; Akiyama, Masayuki; Goto, Tomotsugu; Koyama, Yusei; Ohyama, Youich; Yamamura, Issei

2017-05-01

We investigate the star-forming activity of a sample of infrared (IR)-bright dust-obscured galaxies (DOGs) that show an extreme red color in the optical and IR regime, {(I-[22])}{AB}> 7.0. Combining an IR-bright DOG sample with the flux at 22 μm > 3.8 mJy discovered by Toba & Nagao with the IRAS faint source catalog version 2 and AKARI far-IR (FIR) all-sky survey bright source catalog version 2, we selected 109 DOGs with FIR data. For a subsample of seven IR-bright DOGs with spectroscopic redshifts (0.07< z< 1.0) that were obtained from the literature, we estimated their IR luminosity, star formation rate (SFR), and stellar mass based on the spectral energy distribution fitting. We found that (1) the WISE 22 μm luminosity at the observed frame is a good indicator of IR luminosity for IR-bright DOGs and (2) the contribution of the active galactic nucleus to IR luminosity increases with IR luminosity. By comparing the stellar mass and SFR relation for our DOG sample and the literature, we found that most of the IR-bright DOGs lie significantly above the main sequence of star-forming galaxies at similar redshift, indicating that the majority of IRAS- or AKARI-detected IR-bright DOGs are starburst galaxies.

An analysis of source structure effects in radio interferometry measurements

NASA Technical Reports Server (NTRS)

Thomas, J. B.

1980-01-01

To begin a study of structure effects, this report presents a theoretical framework, proposes an effective position approach to structure corrections based on brightness distribution measurements, and analyzes examples of analytical and measured brightness distributions. Other topics include the effect of the frequency dependence of a brightness distribution on bandwidth synthesis (BWS) delay, the determination of the absolute location of a measured brightness distribution, and structure effects in dual frequency calibration of charged particle delays. For the 10 measured distributions analyzed, it was found that the structure effect in BWS delay at X-band (3.6 cm) can reach 30 cm, but typically falls in the range of 0 to 5 cm. A trial limit equation that is dependent on visibility was successfully tested against the 10 measured brightness distributions (seven sources). If the validity of this particular equation for an upper limit can be established for nearly all sources, the structure effect in BWS delay could be greatly reduced without supplementary measurements of brightness distributions.

Microbial Influences on Trace Metal Cycling in a Meromictic Lake, Fayetteville Green Lake, NY

NASA Astrophysics Data System (ADS)

Zerkle, A. L.; House, C.; Kump, L.

2002-12-01

Microorganisms can exist in aquatic environments at very high cell densities of up to 1011 cells/L, and can accumulate significant quantities of trace metals. Bacteria actively take up bioactive trace metals, including Fe, Zn, Mn, Co, Ni, Cu, and Mo, which function as catalytic centers in metalloproteins and metal-activated enzymes involved in virtually all cellular functions. In addition, bacteria may catalyze the release of trace metals from inorganic substrates by processes such as the reduction of iron and manganese oxides, suggesting that trace metal distributions within a natural environment dominated by microbial processes may be controlled primarily by microbial ecology. Fayetteville Green Lake (FGL), NY, is a permanently stratified meromictic lake that has a well-oxygenated surface water mass (mixolimnion) overlying a relatively stagnant, anoxic deep water mass (monimolimnion). A chemocline separates the water masses at around 20m depth, where oxygen concentrations decrease and sulfate and methane concentrations increase. In addition, previous studies have indicated that trace metals such as V, Cr, Co, Mn, and Fe reach elevated concentrations at the chemocline. Using fluorescent in situ hybridization (FISH) of FGL samples from depths of up to 40m with bacterial and archaeal probes, we have shown that fluctuating redox conditions within the FGL water column correlate with significant variations in the composition and distribution of microbial populations with depth. The mixolimnion is dominated by Eubacteria, with increasing concentrations of Archaea in the lower anoxic zone. Increases in microbial cell densities coincide with increases in trace metals at the chemocline, suggesting microbial activity may be responsible for trace metal release at this boundary. 16S rRNA PCR cloning techniques are currently being used to identify dominant microbial populations at various levels within the FGL water column. Future studies will focus on the potential for these dominant microorganisms to influence trace metal cycling and bioavailability in the FGL water column.

Radio core dominance of Fermi blazars

NASA Astrophysics Data System (ADS)

Pei, Zhi-Yuan; Fan, Jun-Hui; Liu, Yi; Yuan, Yi-Hai; Cai, Wei; Xiao, Hu-Bing; Lin, Chao; Yang, Jiang-He

2016-07-01

During the first 4 years of mission, Fermi/LAT detected 1444 blazars (3FGL) (Ackermann et al. in Astrophys. J. 810:14, 2015). Fermi/LAT observations of blazars indicate that Fermi blazars are luminous and strongly variable with variability time scales, for some cases, as short as hours. Those observations suggest a strong beaming effect in Fermi/LAT blazars. In the present work, we will investigate the beaming effect in Fermi/LAT blazars using a core-dominance parameter, R = S_{core}/ S_{ext.}, where S_{core} is the core emission, while S_{ext.} is the extended emission. We compiled 1335 blazars with available core-dominance parameter, out of which 169 blazars have γ-ray emission (from 3FGL). We compared the core-dominance parameters, log R, between the 169 Fermi-detected blazars (FDBs) and the rest non-Fermi-detected blazars (non-FDBs), and we found that the averaged values are < log Rrangle = 0.99±0.87 for FDBs and < log Rrangle = -0.62±1.15 for the non-FDBs. A K-S test shows that the probability for the two distributions of FDBs and non-FDBs to come from the same parent distribution is near zero (P =9.12×10^{-52}). Secondly, we also investigated the variability index (V.I.) in the γ-ray band for FDBs, and we found V.I.=(0.12 ±0.07) log R+(2.25±0.10), suggesting that a source with larger log R has larger V.I. value. Thirdly, we compared the mean values of radio spectral index for FDBs and non-FDBs, and we obtained < α_{radio}rangle =0.06±0.35 for FDBs and < α_{radio}rangle =0.57±0.46 for non-FDBs. If γ-rays are composed of two components like radio emission (core and extended components), then we can expect a correlation between log R and the γ-ray spectral index. When we used the radio core-dominance parameter, log R, to investigate the relationship, we found that the spectral index for the core component is α_{γ}|_{core} = 1.11 (a photon spectral index of α_{γ}^{ph}|_{core} = 2.11) and that for the extended component is α_{γ}|_{ext.} = 0.70 (a photon spectral index of α_{γ}^{ph}|_{ext.} = 1.70). Some discussions are also presented.

Broadband Observations of High Redshift Blazars

NASA Astrophysics Data System (ADS)

Paliya, Vaidehi S.; Parker, M. L.; Fabian, A. C.; Stalin, C. S.

2016-07-01

We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2-3303 (z = 2.40) using quasi-simultaneous data from the Swift, Nuclear Spectroscopic Telescope Array (NuSTAR) and the Fermi-Large Area Telescope (LAT) and also archival XMM-Newton observations. Other than 3FGL J1656.2-3303, none of the sources were known as γ-ray emitters, and our analysis of ˜7.5 yr of LAT data reveals the first time detection of statistically significant γ-ray emission from CGRaBS J0225+1846. We generate the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of NuSTAR observations and reproduce them using a one-zone leptonic emission model. The optical-UV emission in all the objects can be explained by radiation from the accretion disk, whereas the X-ray to γ-ray windows of the SEDs are found to be dominated by inverse Compton scattering off the broad line region photons. All of them host black holes that are billions of solar masses. Comparing the accretion disk luminosity and the jet power of these sources with a large sample of blazars, we find them to occupy a high disk luminosity-jet power regime. We also investigate the X-ray spectral properties of the sources in detail with a major focus on studying the causes of soft X-ray deficit, a feature generally seen in high redshift radio-loud quasars. We summarize that this feature could be explained based on the intrinsic curvature in the jet emission rather than being due to the external effects predicted in earlier studies, such as host galaxy and/or warm absorption.

The third catalog of active galactic nuclei detected by the Fermi large area telescope

DOE PAGES

Ackermann, M.; Ajello, M.; Atwood, W. B.; ...

2015-08-25

We present the third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC). It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (more » $$| b| \\gt 10^\\circ $$), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. There were about 50% of the BL Lacs that had no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. Furthermore, the energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.« less

Origin of X-Ray and Gamma-Ray Emission from the Galactic Central Region

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

Chernyshov, D. O.; Dogiel, V. A.; Cheng, K.-S.

We study a possible connection between different non-thermal emissions from the inner few parsecs of the Galaxy. We analyze the origin of the gamma-ray source 2FGL J1745.6−2858 (or 3FGL J1745.6−2859c) in the Galactic Center (GC) and the diffuse hard X-ray component recently found by the Nuclear Spectroscopic Telescope Array , as well as the radio emission and processes of hydrogen ionization from this area. We assume that a source in the GC injected energetic particles with power-law spectrum into the surrounding medium in the past or continues to inject until now. The energetic particles may be protons, electrons, or amore » combination of both. These particles diffuse to the surrounding medium and interact with gas, magnetic field, and background photons to produce non-thermal emissions. We study the spectral and spatial features of the hard X-ray emission and gamma-ray emission by the particles from the central source. Our goal is to examine whether the hard X-ray and gamma-ray emissions have a common origin. Our estimations show that, in the case of pure hadronic models, the expected flux of hard X-ray emission is too low. Despite the fact that protons can produce a non-zero contribution in gamma-ray emission, it is unlikely that they and their secondary electrons can make a significant contribution in hard X-ray flux. In the case of pure leptonic models, it is possible to reproduce both X-ray and gamma-ray emissions for both transient and continuous supply models. However, in the case of the continuous supply model, the ionization rate of molecular hydrogen may significantly exceed the observed value.« less

VizieR Online Data Catalog: XMM-Newton Bright Serendipitous Survey (Della Ceca+, 2004)

NASA Astrophysics Data System (ADS)

Della Ceca, R.; Maccacaro, T.; Caccianiga, A.; Severgnini, P.; Braito, V.; Barcons, X.; Carrera, F. J.; Watson, M. G.; Tedds, J. A.; Brunner, H.; Lehmann, I.; Page, M. J.; Lamer, G.; Schwope, A.

2005-09-01

We present here "The XMM-Newton Bright Serendipitous Survey", composed of two flux-limited samples: the XMM-Newton Bright Source Sample (BSS, hereafter) and the XMM-Newton "Hard" Bright Source Sample (HBSS, hereafter) having a flux limit of fX~7x10-14erg/cm2/s in the 0.5-4.5keV and 4.5-7.5keV energy band, respectively. After discussing the main goals of this project and the survey strategy, we present the basic data on a complete sample of 400 X-ray sources (389 of them belong to the BSS, 67 to the HBSS with 56 X-ray sources in common) derived from the analysis of 237 suitable XMM-Newton fields (211 for the HBSS). At the flux limit of the survey we cover a survey area of 28.10 (25.17 for the HBSS) sq. deg. The extragalactic number-flux relationships (in the 0.5-4.5keV and in the 4.5-7.5keV energy bands) are in good agreement with previous and new results making us confident about the correctness of data selection and analysis. (5 data files).

Swift/XRT follow-up of the flaring blazar PKS 1424-41

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2013-01-01

Following the optical and gamma-ray flaring activity of the flat spectrum radio quasar PKS 1424-41 (also known as 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31) detected by ATOM and Fermi LAT on 2013 January 6 (ATel #4714), a Swift target of opportunity observation was performed on January 7.

Orbital Dynamics of Candidate Transitional Millisecond Pulsar 3FGL J1544.6-1125: An unusually face-on system

NASA Astrophysics Data System (ADS)

Britt, Christopher T.; Strader, Jay; Chomiuk, Laura; Halpern, Jules P.; Tremou, Evangelina; Peacock, Mark; Salinas, Ricardo

2018-01-01

We present the orbital solution for the donor star of the candidate transitional millisecond pulsar 3FGL J1544.6-1125, currently observed as an accreting low-mass X-ray binary. The orbital period is 0.2415361(36) days, entirely consistent with the spectral classification of the donor star as a mid to late K dwarf. The semi-amplitude of the radial velocity curve is exceptionally low at K2=39.3+/-1.5 km s-1, implying a remarkably face-on inclination in the range 5-8o, depending on the neutron star and donor masses. After determining the veiling of the secondary, we derive a distance to the binary of 3.8+/-0.7 kpc, yielding a 0.3-10 keV X-ray luminosity of 6.1+/-1.9 x1033 erg s-1, similar to confirmed transitional millisecond pulsars. As face-on binaries rarely occur by chance, we discuss the possibility that Fermi-selected samples of transitional milli-second pulsars in the sub-luminous disk state are affected by beaming. By phasing emission line strength on the spectroscopic ephemeris, we find coherent variations, and argue that some optical light originates from emission from an asymmetric shock originating near the inner disk.

Fermi LAT detection of renewed GeV flaring activity from PKS 0426-380

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2012-12-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object PKS 0426-380 (also known as 2FGL J0428.6-3756, Nolan et al. 2012, ApJS, 199, 31, and RX J0428.6-3756) with radio coordinates R.A.: 67.16843 deg, Dec: -37.93877 deg, J2000 (Johnston et al. 1995, AJ, 110, 880) and redshift z=1.111 (Heidt et al....

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).

Fermi LAT detection of a GeV flare from the high redshift BL Lac object PKS 2131-021

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2012-08-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object PKS 2131-021 (also known as 2FGL J2133.8-0154, Nolan et al. 2012, ApJS, 199, 31, and 4C -02.81) placed at radio coordinates R.A.: 323.5429567 deg, Dec.: -1.8881217 deg (J2000, Johnston et al. 1995, AJ, 110, 880).

Fermi LAT detection of gamma-ray flaring activity from the blazar MG J221916+1806 through the Fermi All-sky Variability Analysis (FAVA)

NASA Astrophysics Data System (ADS)

Ajello, M.; Kocevski, D.; Gasparrini, D.; Buehler, R.; Thompson, D.; Ciprini, S.

2014-03-01

During the week between March 17 and March 24, 2014, the Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increased gamma-ray activity from a source positionally coincident with the flat-spectrum radio quasar MG J221916+1806 (also known as 2FGL J2219.1+1805, Nolan et al., 2012, ApJS, 199, 31, and CGRaBS J2219+1806, Healey et al. ...

iPTF report of bright transients

NASA Astrophysics Data System (ADS)

Cannella, Chris; Kuesters, Daniel; Ferretti, Raphael; Blagorodnova, Nadejda; Adams, Scott; Kupfer, Thomas; Neill, James D.; Walters, Richard; Yan, Lin; Kulkarni, Shri

2017-02-01

The intermediate Palomar Transient Factory (iPTF; ATel #4807) reports the following bright ( Our automated candidate vetting to distinguish a real astrophysical source (1.0) from bogus artifacts (0.0) is powered by three generations of machine learning algorithms: RB2 (Brink et al. 2013MNRAS.435.1047B), RB4 (Rebbapragada et al. 2015AAS...22543402R), and RB5 (Wozniak et al. 2013AAS...22143105W).

AzTEC/ASTE 1.1 mm Deep Surveys: Number Counts and Clustering of Millimeter-bright Galaxies

NASA Astrophysics Data System (ADS)

Hatsukade, B.; Kohno, K.; Aretxaga, I.; Austermann, J. E.; Ezawa, H.; Hughes, D. H.; Ikarashi, S.; Iono, D.; Kawabe, R.; Matsuo, H.; Matsuura, S.; Nakanishi, K.; Oshima, T.; Perera, T.; Scott, K. S.; Shirahata, M.; Takeuchi, T. T.; Tamura, Y.; Tanaka, K.; Tosaki, T.; Wilson, G. W.; Yun, M. S.

2010-10-01

We present number counts and clustering properties of millimeter-bright galaxies uncovered by the AzTEC camera mounted on the Atacama Submillimeter Telescope Experiment (ASTE). We surveyed the AKARI Deep Field South (ADF-S), the Subaru/XMM Newton Deep Field (SXDF), and the SSA22 fields with an area of ~0.25 deg2 each with an rms noise level of ~0.4-1.0 mJy. We constructed differential and cumulative number counts, which provide currently the tightest constraints on the faint end. The integration of the best-fit number counts in the ADF-S find that the contribution of 1.1 mm sources with fluxes >=1 mJy to the cosmic infrared background (CIB) at 1.1 mm is 12-16%, suggesting that the large fraction of the CIB originates from faint sources of which the number counts are not yet constrained. We estimate the cosmic star-formation rate density contributed by 1.1 mm sources with >=1 mJy using the best-fit number counts in the ADF-S and find that it is lower by about a factor of 5-10 compared to those derived from UV/optically-selected galaxies at z~2-3. The average mass of dark halos hosting bright 1.1 mm sources was calculated to be 1013-1014 Msolar. Comparison of correlation lengths of 1.1 mm sources with other populations and with a bias evolution model suggests that dark halos hosting bright 1.1 mm sources evolve into systems of clusters at present universe and the 1.1 mm sources residing the dark halos evolve into massive elliptical galaxies located in the center of clusters.

Multiwavelength Study of the Bright X-ray Source Population in the Interacting Galaxies NGC 5774/NGC 5775

NASA Technical Reports Server (NTRS)

Ghosh, Kajal K.; Swartz, Douglas A.; Tennant, Allyn F.; Saripalli, Lakshmi; Gandhi, Poshak; Foellmi, Cedric; Gutierrez, Carlos M.; Lopez-Corredoira, Martin

2006-01-01

The X-ray source population in the field of the interacting pair of galaxies NGC 5774/5775 is reported. A total of 49 discrete sources are detected, including 12 ultraluminous X-ray source candidates with lum inosities above 10(exp 39)erg/s in the 0.5 - 8.0 keV X-ray band. Several of these latter are transient X-ray sources that fall below detect ion levels in one of two X-ray observations spaced 15 months apart. X-ray source positions are mapped onto optical and radio images to sear ch for potential counterparts. Eleven sources have optically-bright c ounterparts. Optical colors are used to differentiate these sources, which are mostly located outside the optical extent of the interacting galaxies, as potential globular clusters (3 sources) and quasars (5) . Follow-up optical spectroscopy confirms two of the latter are background quasars.

Multiwavelength Observations of the Redback Millisecond Pulsar J1048+2339

DOE PAGES

Deneva, J. S.; Ray, P. S.; Camilo, F.; ...

2016-05-26

In this paper, we report on radio timing and multiwavelength observations of the 4.66 ms redback pulsar J1048+2339, which was discovered in an Arecibo search targeting the Fermi-Large Area Telescope source 3FGL J1048.6+2338. Two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar. PSR J1048+2339 is in a 6 hr binary and exhibits radio eclipses over half the orbital period and rapid orbital period variations. The companion has a minimum mass of 0.3 M ⊙, and we have identified a V ~ 20 variable optical counterpart in data from several surveys. The phasing ofmore » its ~1 mag modulation at the orbital period suggests highly efficient and asymmetric heating by the pulsar wind, which may be due to an intrabinary shock that is distorted near the companion, or to the companion's magnetic field channeling the pulsar wind to specific locations on its surface. Finally, we also present gamma-ray spectral analysis of the source and preliminary results from searches for gamma-ray pulsations using the radio ephemeris.« less

OVERVIEW OF MONO-ENERGETIC GAMMA-RAY SOURCES & APPLICATIONS

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

Hartemann, F V; Albert, F; Anderson, G G

2010-05-18

Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable Mono-Energetic Gamma-ray (MEGa-ray) source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC NAL will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energymore » range via Compton scattering. This MEGa-ray source will be used to excite nuclear resonance fluorescence in various isotopes. Applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications, including nuclear resonance fluorescence. In conclusion, we have optimized the design of a high brightness Compton scattering gamma-ray source, specifically designed for NRF applications. Two different parameters sets have been considered: one where the number of photons scattered in a single shot reaches approximately 7.5 x 10{sup 8}, with a focal spot size around 8 {micro}m; in the second set, the spectral brightness is optimized by using a 20 {micro}m spot size, with 0.2% relative bandwidth.« less

Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

NASA Astrophysics Data System (ADS)

Smith, Anthony J.; Loveday, Jon; Cross, Nicholas J. G.

2009-08-01

We present luminosity and surface-brightness distributions of 40111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimate of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best-fitting Schechter function parameters for the K-band luminosity function are found to be M* - 5 logh = -23.19 +/- 0.04,α = -0.81 +/- 0.04 and φ* = (0.0166 +/- 0.0008)h3Mpc-3, although the Schechter function provides a poor fit to the data at high and low luminosity, while the luminosity density in the K band is found to be j = (6.305 +/- 0.067) × 108LsolarhMpc-3. However, we caution that there are various known sources of incompleteness and uncertainty in our results. Using mass-to-light ratios determined from the optical colours, we estimate the stellar mass function, finding good agreement with previous results. Possible improvements are discussed that could be implemented when extending this analysis to the full LAS.

VizieR Online Data Catalog: Unidentified gamma-ray sources. IV. X-ray (Paggi+, 2013)

NASA Astrophysics Data System (ADS)

Paggi, A.; Massaro, F.; D'Abrusco, R.; Smith, H. A.; Masetti, N.; Giroletti, M.; Tosti, G.; Funk, S.

2013-11-01

The initial sample considered in our analysis is constituted by the 299 unidentified gamma-ray sources (UGSs) in the 2FGL catalog that do not present any γ-ray analysis flag (Nolan et al. 2012, Cat. J/ApJS/199/31). After Fermi was launched, the Swift XRT Survey of Fermi Unassociated Sources was started in order to perform follow-up observations of the unidentified gamma-ray sources (UGSs) in an attempt to find their potential X-ray counterparts (PI: A. Falcone). We analyze all data collected between the beginning of the follow-up program until 2013 March 31. We note that 203 of the 205 UGSs that constitute our sample have been also observed in the optical and UV by UVOT. We then produced for each X-ray observation the corresponding merged UVOT event files, adopting standard procedures. (6 data files).

VizieR Online Data Catalog: Blazars with γ-ray counterparts. II. (Massaro+, 2013)

NASA Astrophysics Data System (ADS)

Massaro, F.; D'Abrusco, R.; Paggi, A.; Masetti, N.; Giroletti, M.; Tosti, G.; Smith, H. A.; Funk, S.

2013-06-01

Our primary sample of unidentified γ-ray sources (UGSs) consists of all the sources for which no counterpart was assigned at low energies in the 2FGL or in the 2LAC (Nolan et al. 2012, Cat. J/ApJS/199/31; Ackermann et al. 2011, Cat. J/ApJ/743/171, respectively), for a total of 590 γ-ray objects. We considered and analyzed independently two subsamples of UGSs, distinguishing the 299 Fermi sources without any γ-ray analysis flags from the other 291 objects that have a warning in their γ-ray detection. The complete description of our association procedure together with the estimates of its efficiency and its completeness can be found in D'Abrusco et al. (Paper I, 2013, Cat. J/ApJS/206,12). (9 data files).

Quadruple sulfur isotope constraints on the origin and cycling of volatile organic sulfur compounds in a stratified sulfidic lake

NASA Astrophysics Data System (ADS)

Oduro, Harry; Kamyshny, Alexey; Zerkle, Aubrey L.; Li, Yue; Farquhar, James

2013-11-01

We have quantified the major forms of volatile organic sulfur compounds (VOSCs) distributed in the water column of stratified freshwater Fayetteville Green Lake (FGL), to evaluate the biogeochemical pathways involved in their production. The lake's anoxic deep waters contain high concentrations of sulfate (12-16 mmol L-1) and sulfide (0.12 μmol L-1 to 1.5 mmol L-1) with relatively low VOSC concentrations, ranging from 0.1 nmol L-1 to 2.8 μmol L-1. Sulfur isotope measurements of combined volatile organic sulfur compounds demonstrate that VOSC species are formed primarily from reduced sulfur (H2S/HS-) and zero-valent sulfur (ZVS), with little input from sulfate. Thedata support a role of a combination of biological and abiotic processes in formation of carbon-sulfur bonds between reactive sulfur species and methyl groups of lignin components. These processes are responsible for very fast turnover of VOSC species, maintaining their low levels in FGL. No dimethylsulfoniopropionate (DMSP) was detected by Electrospray Ionization Mass Spectrometry (ESI-MS) in the lake water column or in planktonic extracts. These observations indicate a pathway distinct from oceanic and coastal marine environments, where dimethylsulfide (DMS) and other VOSC species are principally produced via the breakdown of DMSP by plankton species.

Fermi LAT detection of a GeV flare from the blazar PKS 0250-225

NASA Astrophysics Data System (ADS)

Dutka, Michael; Ojha, Roopesh

2012-11-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar PKS 0250-225 (also known as 2FGL J0252.7-2218, Nolan et al. 2012 ApJS, 199, 31). PKS 0250-225 has the coordinates RA=02h52m47.9536s, DEC=-22d19m25.465s, J2000, (Beasley et al. 2002 ApJS, 141, 13) and redshift z=1.419 (Shaw et al.

Fermi LAT Detection of a GeV Flare from FSRQ PKS 2320-035

NASA Astrophysics Data System (ADS)

Carpenter, Bryce; Ojha, Roopesh

2013-04-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar PKS 2320-035 (also known as 2FGL J2323.6-0316, Nolan et al. 2012, ApJS, 199, 31). PKS 2320-035 has coordinates RA=23h23m31.9537s DEC=-03d17m05.023s, J2000, (Johnston et al. 1995, AJ, 110, 880) and redshift z=1.41 (Browne et al.

Compact radio sources in the starburst galaxy M82 and the Sigma-D relation for supernova remnants

NASA Technical Reports Server (NTRS)

Huang, Z. P.; Thuan, T. X.; Chevalier, R. A.; Condon, J. J.; Yin, Q. F.

1994-01-01

We have obtained an 8.4 GHz Very Large Array (VLA) A-array map of the starburst galaxy M82 with a resolution Full Width at Half Maximum (FWHM) approximately 0.182 sec. About 50 compact radio sources in the central region of M82 were detected with a peak surface brightness approximately greater than 10(exp -17) W/Hz/sq m/sr. Comparison with previous observations shows that most sources are declining in flux. Three previously visible sources have faded into the background of our map (approximately less than 0.2 mJy/beam), while a few sources, including the second and third brightest radio sources in M82, may have increased slightly in flux over the last decade. No new radio supernova was found. The birth rate of the compact radio sources is estimated to be 0.11 + or - 0.05/yr. We attribute the population of such bright, small supernova remnants (SNRs) in M82 to the high pressure in the central region that can truncate the mass loss during a red supergiant phase or allow dense ionized clouds to be present. The compact radio sources obey a Sigma(radio surface brightness) - D(diameter) relation which is remarkably similar to that followed by supernova remnants in the Galaxy and the Magellanic Clouds and by two of the strongest known extragalactic radio supernovae: SN 1986J and SN 1979C. A least-squares fit to the SNR data gives: Sigma(sub 8.4 GHz) (W/Hz/sq m/sr) = 4.4 x 10(exp -16) D(sub pc)(exp -3.5 +/- 0.1) covering seven orders of magnitude in Sigma. Possible selection effects are discussed and a theoretical discussion of the correlation is presented.

Evidence for a Population of High-Redshift Submillimeter Galaxies from Interferometric Imaging

NASA Astrophysics Data System (ADS)

Younger, Joshua D.; Fazio, Giovanni G.; Huang, Jia-Sheng; Yun, Min S.; Wilson, Grant W.; Ashby, Matthew L. N.; Gurwell, Mark A.; Lai, Kamson; Peck, Alison B.; Petitpas, Glen R.; Wilner, David J.; Iono, Daisuke; Kohno, Kotaro; Kawabe, Ryohei; Hughes, David H.; Aretxaga, Itziar; Webb, Tracy; Martínez-Sansigre, Alejo; Kim, Sungeun; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Lowenthal, James D.; Schinnerer, Eva; Smolčić, Vernesa

2007-12-01

We have used the Submillimeter Array to image a flux-limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890 μm with ~2" resolution. All of the sources-two radio-bright and five radio-dim-are detected as single point sources at high significance (>6 σ), with positions accurate to ~0.2" that enable counterpart identification at other wavelengths observed with similarly high angular resolution. All seven have IRAC counterparts, but only two have secure counterparts in deep HST ACS imaging. As compared to the two radio-bright sources in the sample, and those in previous studies, the five radio-dim sources in the sample (1) have systematically higher submillimeter-to-radio flux ratios, (2) have lower IRAC 3.6-8.0 μm fluxes, and (3) are not detected at 24 μm. These properties, combined with size constraints at 890 μm (θ<~1.2''), suggest that the radio-dim submillimeter galaxies represent a population of very dusty starbursts, with physical scales similar to local ultraluminous infrared galaxies, with an average redshift higher than radio-bright sources.

A high brightness proton injector for the Tandetron accelerator at Jožef Stefan Institute

NASA Astrophysics Data System (ADS)

Pelicon, Primož; Podaru, Nicolae C.; Vavpetič, Primož; Jeromel, Luka; Ogrinc Potocnik, Nina; Ondračka, Simon; Gottdang, Andreas; Mous, Dirk J. M.

2014-08-01

Jožef Stefan Institute recently commissioned a high brightness H- ion beam injection system for its existing tandem accelerator facility. Custom developed by High Voltage Engineering Europa, the multicusp ion source has been tuned to deliver at the entrance of the Tandetron™ accelerator H- ion beams with a measured brightness of 17.1 A m-2 rad-2 eV-1 at 170 μA, equivalent to an energy normalized beam emittance of 0.767 π mm mrad MeV1/2. Upgrading the accelerator facility with the new injection system provides two main advantages. First, the high brightness of the new ion source enables the reduction of object slit aperture and the reduction of acceptance angle at the nuclear microprobe, resulting in a reduced beam size at selected beam intensity, which significantly improves the probe resolution for micro-PIXE applications. Secondly, the upgrade strongly enhances the accelerator up-time since H and He beams are produced by independent ion sources, introducing a constant availability of 3He beam for fusion-related research with NRA. The ion beam particle losses and ion beam emittance growth imply that the aforementioned beam brightness is reduced by transport through the ion optical system. To obtain quantitative information on the available brightness at the high-energy side of the accelerator, the proton beam brightness is determined in the nuclear microprobe beamline. Based on the experience obtained during the first months of operation for micro-PIXE applications, further necessary steps are indicated to obtain optimal coupling of the new ion source with the accelerator to increase the normalized high-energy proton beam brightness at the JSI microprobe, currently at 14 A m-2 rad-2 eV-1, with the output current at 18% of its available maximum.

OBSERVATION OF TeV GAMMA RAYS FROM THE FERMI BRIGHT GALACTIC SOURCES WITH THE TIBET AIR SHOWER ARRAY

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

Amenomori, M.; Bi, X. J.; Ding, L. K.

2010-01-20

Using the Tibet-III air shower array, we search for TeV {gamma}-rays from 27 potential Galactic sources in the early list of bright sources obtained by the Fermi Large Area Telescope at energies above 100 MeV. Among them, we observe seven sources instead of the expected 0.61 sources at a significance of 2{sigma} or more excess. The chance probability from Poisson statistics would be estimated to be 3.8 x 10{sup -6}. If the excess distribution observed by the Tibet-III array has a density gradient toward the Galactic plane, the expected number of sources may be enhanced in chance association. Then, themore » chance probability rises slightly, to 1.2 x 10{sup -5}, based on a simple Monte Carlo simulation. These low chance probabilities clearly show that the Fermi bright Galactic sources have statistically significant correlations with TeV {gamma}-ray excesses. We also find that all seven sources are associated with pulsars, and six of them are coincident with sources detected by the Milagro experiment at a significance of 3{sigma} or more at the representative energy of 35 TeV. The significance maps observed by the Tibet-III air shower array around the Fermi sources, which are coincident with the Milagro {>=}3{sigma} sources, are consistent with the Milagro observations. This is the first result of the northern sky survey of the Fermi bright Galactic sources in the TeV region.« less

The HELLAS2XMM survey. XI. Unveiling the nature of X-ray bright optically normal galaxies

NASA Astrophysics Data System (ADS)

Civano, F.; Mignoli, M.; Comastri, A.; Vignali, C.; Fiore, F.; Pozzetti, L.; Brusa, M.; La Franca, F.; Matt, G.; Puccetti, S.; Cocchia, F.

2007-12-01

Aims:X-ray bright optically normal galaxies (XBONGs) constitute a small but significant fraction of hard X-ray selected sources in recent Chandra and XMM-Newton surveys. Even though several possibilities were proposed to explain why a relatively luminous hard X-ray source does not leave any significant signature of its presence in terms of optical emission lines, the nature of XBONGs is still subject of debate. We aim to better understand their nature by means of a multiwavelength and morphological analysis of a small sample of these sources. Methods: Good-quality photometric near-infrared data (ISAAC/VLT) of four low-redshift (z = 0.1{-}0.3) XBONGs, selected from the HELLAS2XMM survey, have been used to search for the presence of the putative nucleus, applying the surface-brightness decomposition technique through the least-squares fitting program GALFIT. Results: The surface brightness decomposition allows us to reveal a nuclear point-like source, likely to be responsible for the X-ray emission, in two out of the four sources. The results indicate that moderate amounts of gas and dust, covering a large solid angle (possibly 4π) at the nuclear source, combined with the low nuclear activity, may explain the lack of optical emission lines. The third XBONG is associated with an X-ray extended source and no nuclear excess is detected in the near infrared at the limits of our observations. The last source is associated to a close (d≤ 1 arcsec) double system and the fitting procedure cannot achieve a firm conclusion. Based on observations made at the European Southern Observatory, Paranal, Chile (ESO Programme ID 69.A-0554).

Pilicides inhibit the FGL chaperone/usher assisted biogenesis of the Dr fimbrial polyadhesin from uropathogenic Escherichia coli

PubMed Central

2013-01-01

Background The global spread of bacterial resistance has given rise to a growing interest in new anti-bacterial agents with a new strategy of action. Pilicides are derivatives of ring-fused 2-pyridones which block the formation of the pili/fimbriae crucial to bacterial pathogenesis. They impair by means of a chaperone-usher pathway conserved in the Gram-negative bacteria of adhesive structures biogenesis. Pili/fimbriae of this type belong to two subfamilies, FGS and FGL, which differ in the details of their assembly mechanism. The data published to date have shown that pilicides inhibit biogenesis of type 1 and P pili of the FGS type which are encoded by uropathogenic E. coli strains. Results We evaluated the anti-bacterial activity of literature pilicides as blockers of the assembly of a model example of FGL-type adhesive structures, – the Dr fimbriae encoded by a dra gene cluster of uropathogenic Escherichia coli strains. In comparison to the strain grown without pilicide, the Dr+ bacteria cultivated in the presence of the 3.5 mM concentration of pilicides resulted in a reduction of 75 to 87% in the adherence properties to CHO cells expressing Dr fimbrial DAF receptor protein. Using quantitative assays, we determined the amount of Dr fimbriae in the bacteria cultivated in the presence of 3.5 mM of pilicides to be reduced by 75 to 81%. The inhibition effect of pilicides is concentration dependent, which is a crucial property for their use as potential anti-bacterial agents. The data presented in this article indicate that pilicides in mM concentration effectively inhibit the adherence of Dr+ bacteria to the host cells, – the crucial, initial step in bacterial pathogenesis. Conclusions Structural analysis of the DraB chaperone clearly showed it to be a model of the FGL subfamily of chaperones. This permits us to conclude that analyzed pilicides in mM concentration are effective inhibitors of the assembly of adhesins belonging to the Dr family, and more speculatively, of other FGL-type adhesive organelles. The presented data and those published so far permit to speculate that based on the conservation of chaperone-usher pathway in Gram-negative bacteria , the pilicides are potential anti-bacterial agents with activity against numerous pathogens, the virulence of which is dependent on the adhesive structures of the chaperone-usher type. PMID:23758700

An X-ray survey of variable radio bright quasars

NASA Technical Reports Server (NTRS)

Henriksen, M. J.; Marshall, F. E.; Mushotzky, R. F.

1984-01-01

A sample consisting primarily of radio bright quasars was observed in X-rays with the Einstein Observatory for times ranging from 1500 to 5000 seconds. Detected sources had luminosities ranging from 0.2 to 41.0 x 10 to the 45th power ergs/sec in the 0.5 to 4.5 keV band. Three of the fourteen objects which were reobserved showed flux increases greater than a factor of two on a time scale greater than six months. No variability was detected during the individual observations. The optical and X-ray luminosities are correlated, which suggests a common origin. However, the relationship (L sub x is approximately L sub op to the (.89 + or - .15)) found for historic radio variables may be significantly different than that reported for other radio bright sources. Some of the observed X-ray fluxes were substantially below the predicted self-Compton flux, assuming incoherent synchrotron emission and using VLBI results to constrain the size of the emission region, which suggests relativistic expansion in these sources. Normal CIV emission in two of the sources with an overpredicted Compton component suggests that although they, like BL Lac objects, have highly relativistic material apparently moving at small angle to the line of sight, they have a smaller fraction of the continuum component in the beam.

Boson Sampling with Single-Photon Fock States from a Bright Solid-State Source.

PubMed

Loredo, J C; Broome, M A; Hilaire, P; Gazzano, O; Sagnes, I; Lemaitre, A; Almeida, M P; Senellart, P; White, A G

2017-03-31

A boson-sampling device is a quantum machine expected to perform tasks intractable for a classical computer, yet requiring minimal nonclassical resources as compared to full-scale quantum computers. Photonic implementations to date employed sources based on inefficient processes that only simulate heralded single-photon statistics when strongly reducing emission probabilities. Boson sampling with only single-photon input has thus never been realized. Here, we report on a boson-sampling device operated with a bright solid-state source of single-photon Fock states with high photon-number purity: the emission from an efficient and deterministic quantum dot-micropillar system is demultiplexed into three partially indistinguishable single photons, with a single-photon purity 1-g^{(2)}(0) of 0.990±0.001, interfering in a linear optics network. Our demultiplexed source is between 1 and 2 orders of magnitude more efficient than current heralded multiphoton sources based on spontaneous parametric down-conversion, allowing us to complete the boson-sampling experiment faster than previous equivalent implementations.

MAXI J1820+070 has optical period of 3.4 hours

NASA Astrophysics Data System (ADS)

Richmond, Michael

2018-05-01

I have observed the transient source MAXI J1820+070 in the optical since 2018 March 24. In the past two weeks, the source has started to show long-term variations in brightness of amplitude approximately 0.03 - 0.10 magnitude.

BROADBAND OBSERVATIONS OF HIGH REDSHIFT BLAZARS

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

Paliya, Vaidehi S.; Parker, M. L.; Fabian, A. C.

We present a multi-wavelength study of four high redshift blazars, S5 0014+81 ( z = 3.37), CGRaBS J0225+1846 ( z = 2.69), BZQ J1430+4205 ( z = 4.72), and 3FGL J1656.2−3303 ( z = 2.40) using quasi-simultaneous data from the Swift , Nuclear Spectroscopic Telescope Array ( NuSTAR ) and the Fermi -Large Area Telescope (LAT) and also archival XMM-Newton observations. Other than 3FGL J1656.2−3303, none of the sources were known as γ -ray emitters, and our analysis of ∼7.5 yr of LAT data reveals the first time detection of statistically significant γ -ray emission from CGRaBS J0225+1846. We generatemore » the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of NuSTAR observations and reproduce them using a one-zone leptonic emission model. The optical−UV emission in all the objects can be explained by radiation from the accretion disk, whereas the X-ray to γ -ray windows of the SEDs are found to be dominated by inverse Compton scattering off the broad line region photons. All of them host black holes that are billions of solar masses. Comparing the accretion disk luminosity and the jet power of these sources with a large sample of blazars, we find them to occupy a high disk luminosity–jet power regime. We also investigate the X-ray spectral properties of the sources in detail with a major focus on studying the causes of soft X-ray deficit, a feature generally seen in high redshift radio-loud quasars. We summarize that this feature could be explained based on the intrinsic curvature in the jet emission rather than being due to the external effects predicted in earlier studies, such as host galaxy and/or warm absorption.« less

Effects of divergent selection for 8-week body weight on postnatal enzyme activity pattern of 3 fiber types in fast muscles of male broilers (Gallus gallus domesticus).

PubMed

Dahmane Gosnak, R; Erzen, I; Holcman, A; Skorjanc, D

2010-12-01

A divergent selection experiment was conducted for 8-wk BW in chickens. At 3, 6, 9, and 12 wk of age, samples of pectoralis profundus (PP) and biceps femoris (BF) muscles from fast-growing and slow-growing lines were used to estimate the enzyme activities and muscle fiber diameter. Microphotometric measurements made in situ of succinate dehydrogenase (SDH, EC 1.3.99.1) and glycerol-3-phosphate dehydrogenase (GPDH, EC 1.1.99.5) were completed on serial sections of PP and BF muscles from male chickens, in order to examine the ratio of SDH:GPDH activity in single fibers. On the basis of the SDH:GPDH activity ratios, muscle fibers were divided using cluster analysis into 3 populations of different fiber types (O = oxidative, OG = oxidative-glycolytic, and G = glycolytic). Cockerels of the SGL attained an 8.1-fold increase and those of the FGL a 6.8-fold increase in BW at 12 wk compared with that at 3 wk of age. The O, OG, and G type fibers of the BF muscles of the SGL had significantly (P ≤ 0.001) lower SDH:GPDH activity ratios than those of the FGL. A step decrease in the SDH:GPDH activity of O, OG, and G fibers in the PP of both lines occurred, and this differed significantly between SGL and FGL (P ≤ 0.001). Age and line effects influenced the diameter of the 3 fiber types in the BF muscle only. In contrast to this response, all 3 fiber types of the PP muscles reached similar diameters in both lines during the growth process from wk 3 to 12. From the results of this study, we concluded that the activities of metabolic enzymes in skeletal muscle fibers are under the influence of muscle type, age, and selection pressure. Microphotometry is a suitable method for the evaluation of enzyme activity measured in a single muscle fiber. The method enables precise estimation of enzyme activities, especially in muscles composed of populations of different metabolic fiber types.

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

Zemcov, M.; Cooray, A.; Bock, J.

We have observed four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measure a deficit of surface brightness within their central region after removing detected sources. We simulate the effects of instrumental sensitivity and resolution, the source population, and the lensing effect of the clusters to estimate the shape and amplitude of the deficit. The amplitude of the central deficit is a strong function of the surface density and flux distribution of the background sources. We find that for the current best fitting faint end number counts, and excellent lensing models, the most likely amplitudemore » of the central deficit is the full intensity of the cosmic infrared background (CIB). Our measurement leads to a lower limit to the integrated total intensity of the CIB of I{sub 250{mu}m}>0.69{sub -0.03}{sup +0.03}(stat.){sub -0.06}{sup +0.11}(sys.) MJy sr{sup -1}, with more CIB possible from both low-redshift sources and from sources within the target clusters. It should be possible to observe this effect in existing high angular resolution data at other wavelengths where the CIB is bright, which would allow tests of models of the faint source component of the CIB.« less

Brightness measurement of an electron impact gas ion source for proton beam writing applications

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

Liu, N.; Santhana Raman, P.; Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583

We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness thatmore » is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.« less

Brightness measurement of an electron impact gas ion source for proton beam writing applications.

PubMed

Liu, N; Xu, X; Pang, R; Raman, P Santhana; Khursheed, A; van Kan, J A

2016-02-01

We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness that is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.

An image-based search for pulsars among Fermi unassociated LAT sources

NASA Astrophysics Data System (ADS)

Frail, D. A.; Ray, P. S.; Mooley, K. P.; Hancock, P.; Burnett, T. H.; Jagannathan, P.; Ferrara, E. C.; Intema, H. T.; de Gasperin, F.; Demorest, P. B.; Stovall, K.; McKinnon, M. M.

2018-03-01

We describe an image-based method that uses two radio criteria, compactness, and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio sources from the Giant Metrewave Radio Telescope all-sky survey at 150 MHz (TGSS ADR1) found within the error ellipses of unassociated sources from the 3FGL catalogue and a preliminary source list based on 7 yr of LAT data. After follow-up interferometric observations to identify extended or variable sources, a list of 16 compact, steep-spectrum candidates is generated. An ongoing search for pulsations in these candidates, in gamma rays and radio, has found 6 ms pulsars and one normal pulsar. A comparison of this method with existing selection criteria based on gamma-ray spectral and variability properties suggests that the pulsar discovery space using Fermi may be larger than previously thought. Radio imaging is a hitherto underutilized source selection method that can be used, as with other multiwavelength techniques, in the search for Fermi pulsars.

AzTEC/ASTE 1.1 mm Deep Surveys: Number Counts and Clustering of Millimeter-bright Galaxies

NASA Astrophysics Data System (ADS)

Hatsukade, B.

2011-11-01

We present results of a 1.1 mm deep survey of the AKARI Deep Field South (ADF-S) with AzTEC mounted on the Atacama Submillimetre Telescope Experiment (ASTE). We obtained a map of 0.25 deg2 area with an rms noise level of 0.32-0.71 mJy. This is one of the deepest and widest maps thus far at millimetre and submillimetre wavelengths. We uncovered 198 sources with a significance of 3.5-15.6σ, providing the largest catalog of 1.1 mm sources in a contiguous region. Most of the sources are not detected in the far-infrared bands of the AKARI satellite, suggesting that they are mostly at z ≥ 1.5 given the detection limits. We construct differential and cumulative number counts of the ADF-S, the Subaru/XMM Newton Deep Field (SXDF), and the SSA 22 field surveyed by AzTEC/ASTE, which provide currently the tightest constraints on the faint end. The integration of the differential number counts of the ADF-S find that the contribution of 1.1 mm sources with ≥1 mJy to the cosmic infrared background (CIB) at 1.1 mm is 12-16%, suggesting that the large fraction of the CIB originates from faint sources of which number counts are not yet constrained. We estimate the cosmic star-formation rate density contributed by 1.1 mm sources with ≥1 mJy using the differential number counts and find that it is lower by about a factor of 5-10 compared to those derived from UV/optically-selected galaxies at z ~ 2-3. Clustering analyses of AzTEC sources in the ADF-S and the SXDF find that bright (>3 mJy) AzTEC sources are more strongly clustered than faint (< 3 mJy) AzTEC sources and the average mass of dark halos hosting bright AzTEC sources was calculated to be 1013-1014M⊙. Comparison of correlation length of AzTEC sources with other populations and with a bias evolution model suggests that dark halos hosting bright AzTEC sources evolve into systems of clusters at present universe and the AzTEC sources residing the dark halos evolve into massive elliptical galaxies located in the center of clusters.

Origins of sharp cosmic-ray electron structures and the DAMPE excess

NASA Astrophysics Data System (ADS)

Huang, Xian-Jun; Wu, Yue-Liang; Zhang, Wei-Hong; Zhou, Yu-Feng

2018-05-01

Nearby sources may contribute to cosmic-ray electron (CRE) structures at high energies. Recently, the first DAMPE results on the CRE flux hinted at a narrow excess at energy ˜1.4 TeV . We show that in general a spectral structure with a narrow width appears in two scenarios. The first is spectrum broadening for the continuous sources with a δ -function-like injection spectrum. In this scenario, a finite width can develop after propagation through the Galaxy, which can reveal the distance of the source. Well-motivated sources include minispikes and subhalos formed by dark matter (DM) particles χs which annihilate directly into e+e- pairs. The second is phase-space shrinking for burstlike sources with a power-law-like injection spectrum. The spectrum after propagation can shrink at a cooling-related cutoff energy and form a sharp spectral peak. The peak can be more prominent due to the energy-dependent diffusion. In this scenario, the width of the excess constrains both the power index and the distance of the source. Possible such sources are pulsar wind nebulae (PWNe) and supernova remnants (SNRs). We analysis the DAMPE excess and find that the continuous DM sources should be fairly close within ˜0.3 kpc , and the annihilation cross sections are close to the thermal value. For the burstlike source, the narrow width of the excess suggests that the injection spectrum must be hard with power index significantly less than two, the distance is within ˜(3 - 4 ) kpc , and the age of the source is ˜0.16 Myr . In both scenarios, large anisotropies in the CRE flux are predicted. We identify possible candidates of minispike and PWN sources in the current Fermi-LAT 3FGL and ATNF catalog, respectively. The diffuse γ -rays from these sources can be well below the Galactic diffuse γ -ray backgrounds and less constrained by the Fermi-LAT data, if they are located at the low Galactic latitude regions.

HST Imaging of the Brightest z ∼ 8–9 Galaxies from UltraVISTA: The Extreme Bright End of the UV Luminosity Function

NASA Astrophysics Data System (ADS)

Stefanon, Mauro; Labbé, Ivo; Bouwens, Rychard J.; Brammer, Gabriel B.; Oesch, Pascal; Franx, Marijn; Fynbo, Johan P. U.; Milvang-Jensen, Bo; Muzzin, Adam; Illingworth, Garth D.; Le Fèvre, Olivier; Caputi, Karina I.; Holwerda, Benne W.; McCracken, Henry J.; Smit, Renske; Magee, Dan

2017-12-01

We report on the discovery of three especially bright candidate {z}{phot}≳ 8 galaxies. Five sources were targeted for follow-up with the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3), selected from a larger sample of 16 bright (24.8≲ H≲ 25.5 mag) candidate z≳ 8 Lyman break galaxies (LBGs) identified over 1.6 degrees2 of the COSMOS/UltraVISTA field. These were selected as Y and J dropouts by leveraging the deep (Y-to-{K}{{S}}∼ 25.3{--}24.8 mag, 5σ ) NIR data from the UltraVISTA DR3 release, deep ground-based optical imaging from the CFHTLS and Suprime-Cam programs, and Spitzer/IRAC mosaics combining observations from the SMUVS and SPLASH programs. Through the refined spectral energy distributions, which now also include new HyperSuprimeCam g-, r-, i-, z-, and Y-band data, we confirm that 3/5 galaxies have robust {z}{phot}∼ 8.0{--}8.7, consistent with the initial selection. The remaining 2/5 galaxies have a nominal {z}{phot}∼ 2. However, with HST data alone, these objects have increased probability of being at z∼ 9. We measure mean UV continuum slopes β =-1.74+/- 0.35 for the three z∼ 8{--}9 galaxies, marginally bluer than similarly luminous z∼ 4{--}6 in CANDELS but consistent with previous measurements of similarly luminous galaxies at z∼ 7. The circularized effective radius for our brightest source is 0.9 ± 0.3 kpc, similar to previous measurements for a bright z∼ 11 galaxy and bright z∼ 7 galaxies. Finally, enlarging our sample to include the six brightest z∼ 8 LBGs identified over UltraVISTA (i.e., including three other sources from Labbé et al.) we estimate for the first time the volume density of galaxies at the extreme bright end ({M}{UV}∼ -22 mag) of the z∼ 8 UV luminosity function. Despite this exceptional result, the still large statistical uncertainties do not allow us to discriminate between a Schechter and a double-power-law form.

BRIGHTNESS AND FLUCTUATION OF THE MID-INFRARED SKY FROM AKARI OBSERVATIONS TOWARD THE NORTH ECLIPTIC POLE

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

Pyo, Jeonghyun; Jeong, Woong-Seob; Matsumoto, Toshio

2012-12-01

We present the smoothness of the mid-infrared sky from observations by the Japanese infrared astronomical satellite AKARI. AKARI monitored the north ecliptic pole (NEP) during its cold phase with nine wave bands covering from 2.4 to 24 {mu}m, out of which six mid-infrared bands were used in this study. We applied power-spectrum analysis to the images in order to search for the fluctuation of the sky brightness. Observed fluctuation is explained by fluctuation of photon noise, shot noise of faint sources, and Galactic cirrus. The fluctuations at a few arcminutes scales at short mid-infrared wavelengths (7, 9, and 11 {mu}m)more » are largely caused by the diffuse Galactic light of the interstellar dust cirrus. At long mid-infrared wavelengths (15, 18, and 24 {mu}m), photon noise is the dominant source of fluctuation over the scale from arcseconds to a few arcminutes. The residual fluctuation amplitude at 200'' after removing these contributions is at most 1.04 {+-} 0.23 nW m{sup -2} sr{sup -1} or 0.05% of the brightness at 24 {mu}m and at least 0.47 {+-} 0.14 nW m{sup -2} sr{sup -1} or 0.02% at 18 {mu}m. We conclude that the upper limit of the fluctuation in the zodiacal light toward the NEP is 0.03% of the sky brightness, taking 2{sigma} error into account.« less

Evidence for Diverse Optical Emission from Gamma-Ray Burst Sources

NASA Astrophysics Data System (ADS)

Pedersen, H.; Jaunsen, A. O.; Grav, T.; Østensen, R.; Andersen, M. I.; Wold, M.; Kristen, H.; Broeils, A.; Näslund, M.; Fransson, C.; Lacy, M.; Castro-Tirado, A. J.; Gorosabel, J.; Rodríguez Espinosa, J. M.; Pérez, A. M.; Wolf, C.; Fockenbrock, R.; Hjorth, J.; Muhli, P.; Hakala, P.; Piro, L.; Feroci, M.; Costa, E.; Nicastro, L.; Palazzi, E.; Frontera, F.; Monaldi, L.; Heise, J.

1998-03-01

Optical Transients from gamma-ray burst sources, in addition to offering a distance determination, convey important information about the physics of the emission mechanism, and perhaps also about the underlying energy source. As the gamma-ray phenomenon is extremely diverse, with timescales spanning several orders of magnitude, some diversity in optical counterpart signatures appears plausible. We have studied the optical transient that accompanied the gamma-ray burst of 1997 May 8, GRB 970508. Observations conducted at the 2.5 m Nordic Optical Telescope (NOT) and the 2.2 m telescope at the German-Spanish Calar Alto observatory (CAHA) cover the time interval starting 3 hr 5 minutes to 96 days after the high-energy event. This brackets all other published observations, including radio. When analyzed in conjunction with optical data from other observatories, evidence emerges for a composite light curve. The first interval, from 3 to 8 hr after the event, was characterized by a constant or slowly declining brightness. At a later moment, the brightness started increasing rapidly, and reached a maximum approximately 40 hr after the GRB. From that moment, the GRB brightness decayed approximately as a power law of index -1.21. The last observation, after 96 days, mR = 24.28 +/- 0.10, is brighter than the extrapolated power law, and hints that a constant component, mR = 25.50 +/- 0.40, is present. The optical transient is unresolved (FWHM 0.83") at the faintest magnitude level. The brightness of the optical transient, its duration, and the general shape of the light curve set this source apart from the single other optical transient known, that of the 1997 February 28 event.

Bright X-ray transient in the LMC

NASA Astrophysics Data System (ADS)

Saxton, R.; Read, A. M.; Li, D. Y.

2018-01-01

We report a bright X-ray transient in the LMC from an XMM-Newton slew made on 5th January 2018. The source, XMMSL2 J053629.4-675940, had a soft X-ray (0.2-2 keV) count rate in the EPIC-pn detector, medium filter of 1.82+/-0.56 c/s, equivalent to a flux Fx=2.3+/-0.7E-12 ergs/s/cm2 for a nominal spectrum of a power-law of slope 2 absorbed by a column NH=3E20 cm^-2.

High brightness electrodeless Z-Pinch EUV source for mask inspection tools

NASA Astrophysics Data System (ADS)

Horne, Stephen F.; Partlow, Matthew J.; Gustafson, Deborah S.; Besen, Matthew M.; Smith, Donald K.; Blackborow, Paul A.

2012-03-01

Energetiq Technology has been shipping the EQ-10 Electrodeless Z-pinchTM light source since 1995. The source is currently being used for metrology, mask inspection, and resist development. Energetiq's higher brightness source has been selected as the source for pre-production actinic mask inspection tools. This improved source enables the mask inspection tool suppliers to build prototype tools with capabilities of defect detection and review down to 16nm design rules. In this presentation we will present new source technology being developed at Energetiq to address the critical source brightness issue. The new technology will be shown to be capable of delivering brightness levels sufficient to meet the HVM requirements of AIMS and ABI and potentially API tools. The basis of the source technology is to use the stable pinch of the electrodeless light source and have a brightness of up to 100W/mm(carat)2-sr. We will explain the source design concepts, discuss the expected performance and present the modeling results for the new design.

Sharp increase of radio flux in flaring blazar PKS 1424-41

NASA Astrophysics Data System (ADS)

Nemenashi, Pfesesani; Gaylard, Michael; Ojha, Roopesh

2013-02-01

The Hartebeesthoek Radio Astronomy Observatory (HartRAO) 26m telescope has detected a sharp increase in the flux density of PKS 1424-41 (also known as 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31) coinciding with the flaring activity reported at gamma-ray and optical (ATel#4714), X-ray (ATel#4717, ATel#4770) and OIR (ATel#4775) bands. At 8.4 GHz, its flux has risen from 6.1 Jy on 2013 Jan 08 to 7.0 Jy on 2013 Jan 28 and it remains at that level.

Fermi-LAT and Swift-XRT observe exceptionally high activity from the nearby TeV blazar Mrk421

NASA Astrophysics Data System (ADS)

Paneque, D.; D'Ammando, F.; Orienti, M.; Falcon, A.

2013-04-01

The high-synchrotron-peaked BL Lac Mrk421 (also known as 2FGL J1104.4+3812, Nolan et al. 2012, ApJS, 199, 31; R.A.= 11h04m27.3139s, Dec.= +38d12m31.799s, J2000.0, Fey et al. 2004, AJ, 127, 3587), at redshift z=0.03, is the subject of an extensive multi-year and multi-instrument program that aims at characterizing with exquisite detail the temporal evolution of the blazar emission across the electromagnetic spectrum.

Microlensing optical depth towards the Galactic Bulge using bright sources from OGLE-II

NASA Astrophysics Data System (ADS)

Sumi, T.; Woźniak, P.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Zebruń, K.; Szewczyk, O.; Wyrzykowski, L.

2004-12-01

We present a measurement of the microlensing optical depth towards the Galactic Bulge by using bright stars as sources from the central 20 OGLE-II Galactic bulge fields covering a range of 0o

Nist Microwave Blackbody: The Design, Testing, and Verification of a Conical Brightness Temperature Source

NASA Astrophysics Data System (ADS)

Houtz, Derek Anderson

Microwave radiometers allow remote sensing of earth and atmospheric temperatures from space, anytime, anywhere, through clouds, and in the dark. Data from microwave radiometers are high-impact operational inputs to weather forecasts, and are used to provide a vast array of climate data products including land and sea surface temperatures, soil moisture, ocean salinity, cloud precipitation and moisture height profiles, and even wind speed and direction, to name a few. Space-borne microwave radiometers have a major weakness when it comes to long-term climate trends due to their lack of traceability. Because there is no standard, or absolute reference, for microwave brightness temperature, nationally or internationally, individual instruments must each rely on their own internal calibration source to set an absolute reference to the fundamental unit of Kelvin. This causes each subsequent instrument to have a calibration offset and there is no 'true' reference. The work introduced in this thesis addresses this vacancy by proposing and introducing a NIST microwave brightness temperature source that may act as the primary reference. The NIST standard will allow pre-launch calibration of radiometers across a broad range of remote sensing pertinent frequencies between 18 GHz and 220 GHz. The blackbody will be capable of reaching temperatures ranging between liquid nitrogen boiling at approximately 77 K and warm-target temperature of 350 K. The brightness temperature of the source has associated standard uncertainty ranging as a function of frequency between 0.084 K and 0.111 K. The standard can be transferred to the calibration source in the instrument, providing traceability of all subsequent measurements back to the primary standard. The development of the NIST standard source involved predicting and measuring its brightness temperature, and minimizing the associated uncertainty of this quantity. Uniform and constant physical temperature along with well characterized and maximized emissivity are fundamental to a well characterized blackbody. The chosen geometry is a microwave absorber coated copper cone. Electromagnetic and thermal simulations are introduced to optimize the design. Experimental verifications of the simulated quantities confirm the predicted performance of the blackbody.

High-resolution observations of radio-source hot spots at 329 MHz

NASA Technical Reports Server (NTRS)

Linfield, R.; Simon, R. S.

1984-01-01

The hot spots of several luminous double radio sources have been observed at 329 MHz with VLBI at fringe spacings ranging from 0.05 to 0.70 arcsec. Two out of two high-redshift (z = about 0.5) sources, but only one of six low-redshift (z = about 0.05) sources, were detected. For the low-redshift source (3C 234) which was detected, either the hot spot is larger at 329 MHz than at 15 GHz, or else the brightness contrast between it and the surrounding lobe is lower at the lower frequency.

A bright attosecond x-ray pulse train generation in a double-laser-driven cone target

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

Hu, Li-Xiang; Yu, Tong-Pu, E-mail: tongpu@nudt.edu.cn; Shao, Fu-Qiu

By using full three-dimensional particle-in-cell and Monte Carlo simulations, we investigate the generation of a high-brightness attosecond x-ray pulse train in a double-laser-driven cone target. The scheme makes use of two lasers: the first high-intensity laser with a laser peak intensity 1.37 × 10{sup 20 }W/cm{sup 2} irradiates the cone and produces overdense attosecond electron bunches; the second counterpropagating weakly relativistic laser with a laser peak intensity 4.932 × 10{sup 17 }W/cm{sup 2} interacts with the produced electron bunches and a bright x-ray pulse train is generated by Thomson backscattering of the second laser off the attosecond electron bunches. It is shown that the photon fluxmore » rises by 5 times using the cone target as compared with a normal channel. Meanwhile, the x-ray peak brightness increases significantly from 1.4 × 10{sup 21}/(s mm{sup 2} mrad{sup 2} 0.1 keV) to 6.0 × 10{sup 21}/(s mm{sup 2} mrad{sup 2} 0.1 keV), which is much higher than that of the Thomson x-ray source generated from traditional accelerators. We also discuss the influence of the laser and target parameters on the x-ray pulse properties. This compact bright x-ray source may have diverse applications, e.g., the study of electric dynamics and harmonics emission in the atomic scale.« less

Light curve and SED modeling of the gamma-ray binary 1FGL J1018.6–5856: Constraints on the orbital geometry and relativistic flow

DOE PAGES

An, Hongjun; Romani, Roger W.

2017-04-04

We present broadband spectral energy distributions and light curves of the gamma-ray binary 1FGL J1018.6–5856 measured in the X-ray and the gamma-ray bands. We find that the orbital modulation in the low-energy gamma-ray band is similar to that in the X-ray band, suggesting a common spectral component. However, above a GeV the orbital light curve changes significantly. We suggest that the GeV band contains significant flux from a pulsar magnetosphere, while the X-ray to TeV light curves are dominated by synchrotron and Compton emission from an intrabinary shock (IBS). We find that a simple one-zone model is inadequate to explainmore » the IBS emission, but that beamed Synchrotron-self Compton radiation from adiabatically accelerated plasma in the shocked pulsar wind can reproduce the complex multiband light curves, including the variable X-ray spike coincident with the gamma-ray maximum. Furthermore, the model requires an inclination of ~50° and an orbital eccentricity of ~0.35, consistent with the limited constraints from existing optical observations. This picture motivates searches for pulsations from the energetic young pulsar powering the wind shock.« less

Light curve and SED modeling of the gamma-ray binary 1FGL J1018.6–5856: Constraints on the orbital geometry and relativistic flow

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

An, Hongjun; Romani, Roger W.

We present broadband spectral energy distributions and light curves of the gamma-ray binary 1FGL J1018.6–5856 measured in the X-ray and the gamma-ray bands. We find that the orbital modulation in the low-energy gamma-ray band is similar to that in the X-ray band, suggesting a common spectral component. However, above a GeV the orbital light curve changes significantly. We suggest that the GeV band contains significant flux from a pulsar magnetosphere, while the X-ray to TeV light curves are dominated by synchrotron and Compton emission from an intrabinary shock (IBS). We find that a simple one-zone model is inadequate to explainmore » the IBS emission, but that beamed Synchrotron-self Compton radiation from adiabatically accelerated plasma in the shocked pulsar wind can reproduce the complex multiband light curves, including the variable X-ray spike coincident with the gamma-ray maximum. Furthermore, the model requires an inclination of ~50° and an orbital eccentricity of ~0.35, consistent with the limited constraints from existing optical observations. This picture motivates searches for pulsations from the energetic young pulsar powering the wind shock.« less

Light Curve and SED Modeling of the Gamma-Ray Binary 1FGL J1018.6–5856: Constraints on the Orbital Geometry and Relativistic Flow

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

An, Hongjun; Romani, Roger W., E-mail: hjan@chungbuk.ac.kr

We present broadband spectral energy distributions and light curves of the gamma-ray binary 1FGL J1018.6−5856 measured in the X-ray and the gamma-ray bands. We find that the orbital modulation in the low-energy gamma-ray band is similar to that in the X-ray band, suggesting a common spectral component. However, above a GeV the orbital light curve changes significantly. We suggest that the GeV band contains significant flux from a pulsar magnetosphere, while the X-ray to TeV light curves are dominated by synchrotron and Compton emission from an intrabinary shock (IBS). We find that a simple one-zone model is inadequate to explainmore » the IBS emission, but that beamed Synchrotron-self Compton radiation from adiabatically accelerated plasma in the shocked pulsar wind can reproduce the complex multiband light curves, including the variable X-ray spike coincident with the gamma-ray maximum. The model requires an inclination of ∼50° and an orbital eccentricity of ∼0.35, consistent with the limited constraints from existing optical observations. This picture motivates searches for pulsations from the energetic young pulsar powering the wind shock.« less

Technological Challenges to X-Ray FELs

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

Nuhn, Heinz-Dieter

1999-09-16

There is strong interest in the development of x-ray free electron lasers (x-ray FELs). The interest is driven by the scientific opportunities provided by intense, coherent x-rays. An x-ray FEL has all the characteristics of a fourth-generation source: brightness several orders of magnitude greater than presently achieved in third-generation sources, full transverse coherence, and sub-picosecond long pulses. The SLAC and DESY laboratories have presented detailed design studies for X-Ray FEL user facilities around the 0.1 nm wavelength-regime (LCLS at SLAC, TESLA X-Ray FEL at DESY). Both laboratories are engaged in proof-of-principle experiments are longer wavelengths (TTF FEL Phase I atmore » 71 nm, VISA at 600-800 nm) with results expected in 1999. The technologies needed to achieve the proposed performances are those of bright electron sources, of acceleration systems capable of preserving the brightness of the source, and of undulators capable of meeting the magnetic and mechanical tolerances that are required for operation in the SASE mode. This paper discusses the technological challenges presented by the X-Ray FEL projects.« less

Advanced Compton scattering light source R&D at LLNL

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

Albert, F; Anderson, S G; Anderson, G

2010-02-16

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented. At MeV photon energies relevant for nuclear processes, Compton scattering light sources are attractive because of their relative compactness and improved brightness above 100 keV, compared to typical 4th generation synchrotrons. Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable Mono-Energetic Gamma-Ray (MEGa-Ray) light sources based on Compton scattering between a high-brightness, relativistic electron beam and a highmore » intensity laser pulse produced via chirped-pulse amplification (CPA). A new precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. Based on the success of the previous Thomson-Radiated Extreme X-rays (T-REX) Compton scattering source at LLNL, the source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. After a brief presentation of successful nuclear resonance fluorescence (NRF) experiments done with T-REX, the new source design, key parameters, and current status are presented.« less

Production, formation, and transport of high-brightness atomic hydrogen beam studies for the relativistic heavy ion collider polarized source upgrade.

PubMed

Kolmogorov, A; Atoian, G; Davydenko, V; Ivanov, A; Ritter, J; Stupishin, N; Zelenski, A

2014-02-01

The RHIC polarized H(-) ion source had been successfully upgraded to higher intensity and polarization by using a very high brightness fast atomic beam source developed at BINP, Novosibirsk. In this source the proton beam is extracted by a four-grid multi-aperture ion optical system and neutralized in the H2 gas cell downstream from the grids. The proton beam is extracted from plasma emitter with a low transverse ion temperature of ∼0.2 eV which is formed by plasma jet expansion from the arc plasma generator. The multi-hole grids are spherically shaped to produce "geometrical" beam focusing. Proton beam formation and transport of atomic beam were experimentally studied at test bench.

A New Fundamental Plane for Radiatively Efficient Black-hole Sources

NASA Astrophysics Data System (ADS)

Dong, Ai-Jun; Wu, Qingwen; Cao, Xiao-Feng

2014-06-01

In recent years, it has been found that several low/hard states of X-ray binaries (XRBs) follow an "outliers" track in the radio-X-ray correlation (L_R\\propto L_X^{b} and b ~ 1.4), which is much steeper than the former universal track with b ~ 0.6. In this work, we compile a sample of bright radio-quiet active galactic nuclei (AGNs) and find that their hard X-ray photon indices and Eddington ratios are positively correlated, which is similar to that of XRB outliers, where both bright AGNs and XRB outliers have bolometric Eddington ratios >~ 1%L Edd (L Edd is Eddington luminosity). The Eddington-scaled radio-X-ray correlation of these AGNs is also similar to that of XRB outliers, which has the form of L 5 GHz/L Eddvprop(L 2-10 keV/L Edd) c with c ~= 1.59 and 1.53 for AGNs and XRBs, respectively. Both the positively correlated X-ray spectral evolution and the steeper radio-X-ray correlation can be regulated by a radiatively efficient accretion flow (e.g., disk-corona). Based on these similarities, we further present a new fundamental plane for XRB outliers and bright AGNs in black-hole (BH) mass, radio, and X-ray luminosity space: log L_R=1.59^{+0.28}_{-0.22} log L_X- 0.22^{+0.19}_{-0.20}log M_BH-28.97^{+0.45}_{-0.45} with a scatter of σR = 0.51 dex. This fundamental plane is suitable for radiatively efficient BH sources, while the former plane proposed by Merloni et al. and Falcke et al. may be most suitable for radiatively inefficient sources.

Coronal bright points at 6cm wavelength

NASA Technical Reports Server (NTRS)

Fu, Qijun; Kundu, M. R.; Schmahl, E. J.

1988-01-01

Results are presented from observations of bright points at a wavelength of 6-cm using the VLA with a spatial resolution of 1.2 arcsec. During two hours of observations, 44 sources were detected with brightness temperatures between 2000 and 30,000 K. Of these sources, 27 are associated with weak dark He 10830 A features at distances less than 40 arcsecs. Consideration is given to variations in the source parameters and the relationship between ephemeral regions and bright points.

Single Quantum Dot with Microlens and 3D-Printed Micro-objective as Integrated Bright Single-Photon Source

PubMed Central

2017-01-01

Integrated single-photon sources with high photon-extraction efficiency are key building blocks for applications in the field of quantum communications. We report on a bright single-photon source realized by on-chip integration of a deterministic quantum dot microlens with a 3D-printed multilens micro-objective. The device concept benefits from a sophisticated combination of in situ 3D electron-beam lithography to realize the quantum dot microlens and 3D femtosecond direct laser writing for creation of the micro-objective. In this way, we obtain a high-quality quantum device with broadband photon-extraction efficiency of (40 ± 4)% and high suppression of multiphoton emission events with g(2)(τ = 0) < 0.02. Our results highlight the opportunities that arise from tailoring the optical properties of quantum emitters using integrated optics with high potential for the further development of plug-and-play fiber-coupled single-photon sources. PMID:28670600

A non cool-core 4.6-keV cluster around the bright nearby radio galaxy PKS B1416-493

NASA Astrophysics Data System (ADS)

Worrall, D. M.; Birkinshaw, M.

2017-05-01

We present new X-ray (Chandra) and radio (ATCA) observations of the z = 0.09 radio galaxy PKS B1416-493, a member of the southern equivalent of the 3CRR sample. We find the source to be embedded in a previously unrecognized bright kT = 4.6-keV non cool-core cluster. The discovery of new clusters of such high temperature and luminosity within z = 0.1 is rare. The radio source was chosen for observation based on its intermediate FR I/II morphology. We identify a cavity coincident with the northeast lobe, and excess counts associated with the southwest lobe that we interpret as inverse-Compton X-ray emission. The jet power, at 5.3 × 1044 erg s-1, when weighted by radio source density, supports suggestions that radio sources of intermediate morphology and radio power may dominate radio-galaxy heating in the local Universe.

Nebular Line Emission and Stellar Mass of Bright z 8 Galaxies "Super-Eights"

NASA Astrophysics Data System (ADS)

Holwerda, Benne; Bouwens, Rychard; Trenti, Michele; Oesch, Pascal; Labbe, Ivo; Smit, Renske; Roberts-Borsani, Guido; Bernard, Stephanie; Bridge, Joanna

2018-05-01

Searches for the Lyman-alpha emission from the very first galaxies ionizing the Universe have proved to be extremely difficult with limited success beyond z 7 (<3% detections). However, a search of all CANDELS yielded four bright z 8 sources with associated strong Lyman-alpha lines, despite the Universe expected to be 70% neutral at this time. The key to their selection is an extremely red IRAC color ([3.6]-[4.5]> 0.5, Roberts-Borsani+ 2016), indicative of very strong nebular line emission. Do such extreme line emitting galaxies produce most of the photons to reionize the Universe? We propose to expand the sample of bright z 8 galaxies with reliable IRAC colors with seven more Y-band dropouts found with HST and confirmed through HST/Spitzer. The Spitzer observations will test how many of bright z 8 galaxies are IRAC-red and measure both their stellar mass and [OIII]+Hbeta line strength. Together with Keck/VLT spectroscopy, they will address these questions: I) Do all luminous z 8 galaxies show such red IRAC colors ([OIII] emission / hard spectra)? II) Is luminosity or a red IRAC color the dominant predictor for Lyman-alpha emission? III) Or are these sources found along exceptionally transparent sightlines into the early Universe? With 11 bright z 8 sources along different lines-of-sight, all prime targets for JWST, we will aim to determine which of the considered factors (luminosity, color, sight-line) drives the high Lyman-alpha prevalence (100%) and insight into the sources reionizing the Universe.

Accretion processes of radio galaxies at high energies

NASA Astrophysics Data System (ADS)

de Jong, Sandra

2013-10-01

AGN are the luminous (L>10^42 erg/s) cores of active galaxies, powered by accretion onto the central super massive black hole, either via an accretion disk or via a radiatively inefficient accretion flow. There are still several open questions, for example on the launching of jets, which are present in about 10% of the AGN. Another question appeared with the Fermi/LAT gamma-ray survey, which detected many blazars but also a small group of radio galaxies. Radio galaxies are postulated to be blazars where the observer sees the jet at an angle θ>10 degrees allowing a view of both jet and core, rather than only the jet as is the case with blazars. Radio galaxies are divided into two classes, depending on the radio luminosity of the jets. The Fanaroff-Riley I (FR-I) sources have jets that are bright near the core, where the FR-IIs display extended edge-brightened jets. The FR-I sources are connected to the BL Lacs, which are low-luminosity blazars. FR-II types are thought to be the parent population of the luminous FSRQ, which are also blazars. This thesis presents a study of gamma-ray bright radio galaxies. By analysing X-ray and gamma-ray data in addition to creating broad-band spectral energy distributions (SEDs), we studied two examples of this new class of sources. For the FR-II source 3C 111 we analysed Suzaku/XIS and PIN and INTEGRAL IBIS/ISGRI observations to create a X-ray spectrum. We also used a Swift/BAT spectrum from the 58-month survey. The 0.4-200 keV spectrum of the source shows both thermal, Seyfert-like signatures such as an iron K-α line, and non-thermal jet features. We also analysed gamma-ray data from Fermi/LAT. The gamma-ray and X-ray data are combined with historical radio, infrared and optical observations to build the SED, which can be well represented with a non-thermal jet model. The bolometric luminosity of 3C111 is rather low, and the SED model shows rather a BL Lac type than the expected FSRQ. The next source we studied is the nearby FR-I M87. This source has been detected ! in gamma-rays and in the TeV band, but so far not in the hard X-rays (>10 keV). The first part of our analysis was focused on setting an upper limit to the hard X-ray emission of this source, using INTEGRAL IBIS/ISGRI observations. In addition to the standard method we applied several techniques in the analysis process, such as pointing selection and shadowgram treatment, in order to decrease the noise level of the result. Using 5.1 Ms of ISGRI data we determined a 3σ upper limit to the average 20-60 keV flux of f < 3x10^-12 erg/cm^2/s. We have also analysed Suzaku/PIN observations, where we detected M87 for the first time in the hard X-ray band, with a flux of f=1.3x 10^-11 erg/cm^2/s. between 20 and 60 keV. This detection indicates a flare, since the flux is significantly higher than the derived average upper limit. We also analysed Fermi/LAT data and combined this with the X-ray upper limits and historical radio, infrared and optical observations to build a SED. The SED can be modelled as a BL Lac source, which is expected since M87 is a FR-I type. We then also examined the general aspects of gamma-ray bright radio galaxies. Most of these objects are of the FR-I type, and the core of at least one FR-II, 3C 111, is rather BL Lac-like than the expected FSRQ. For the other FR-II sources this might also be the case. The gamma-ray emission originates from the jet, similar as in the case of blazars. Due to the large jet angle, the emission is not observed to be boosted. However, since the gamma-ray emission originates near the black hole, either reflection or a large opening angle can explain the observations. In addition, I contributed to the study of a possible dark matter halo observed with Fermi/LAT in the vicinity of the Virgo cluster. Our work has shown that a population of point sources contributes to this emission. In this thesis, the result of an extended emission analysis and the search for possible counter parts of new sources are presented. ! Finally, the detection of two new X-ray sources using Swift is reported here for the first time. These sources, the BL Lac object BZB J1552+0850 and the Seyfert galaxy LSBC F727-V01, are both located within the 95% error circle of the Fermi/LAT source 2FGL J1551.9+0855. We analysed the X-ray data from the XRT and UV data from the UVOT. The likely counterpart of the Fermi source is rather the blazer BZB J1552+0850, since Seyfert galaxies are rarely gamma-ray emitters. To understand the gamma-ray bright radio galaxies, X-ray observations can be used to can characterise these sources. Using for example the new generation of instruments, such as NuSTAR and ASTRO-H, will help with their superior resolution to distinguish between thermal and non-thermal emission in the X-ray spectrum. Additionally, building SEDs from simultaneous multi-wavelength observations will help constrain the broad-band emission. This will also help to pinpoint the counter part of Fermi/LAT detected sources, which is not trivial due to the large uncertainty in position

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

Kandlakunta, P; Pham, R; Zhang, T

Purpose: To develop and characterize a high brightness multiple-pixel thermionic emission x-ray (MPTEX) source. Methods: Multiple-pixel x-ray sources allow for designs of novel x-ray imaging techniques, such as fixed gantry CT, digital tomosynthesis, tetrahedron beam computed tomography, etc. We are developing a high-brightness multiple-pixel thermionic emission x-ray (MPTEX) source based on oxide coated cathodes. Oxide cathode is chosen as the electron source due to its high emission current density and low operating temperature. A MPTEX prototype has been developed which may contain up to 41 micro-rectangular oxide cathodes in 4 mm pixel spacing. Electronics hardware was developed for source controlmore » and switching. The cathode emission current was evaluated and x-ray measurements were performed to estimate the focal spot size. Results: The oxide cathodes were able to produce ∼110 mA cathode current in pulse mode which corresponds to an emission current density of 0.55 A/cm{sup 2}. The maximum kVp of the MPTEX prototype currently is limited to 100 kV due to the rating of high voltage feedthrough. Preliminary x-ray measurements estimated the focal spot size as 1.5 × 1.3 mm{sup 2}. Conclusion: A MPTEX source was developed with thermionic oxide coated cathodes and preliminary source characterization was successfully performed. The MPTEX source is able to produce an array of high brightness x-ray beams with a fast switching speed.« less

Exploring the connection between radio and GeV-TeV γ-ray emission in the 1FHL and 2FHL AGN samples

NASA Astrophysics Data System (ADS)

Lico, R.; Giroletti, M.; Orienti, M.; Costamante, L.; Pavlidou, V.; D'Ammando, F.; Tavecchio, F.

2017-10-01

Context. With the advent of the Fermi Large Area Telescope (LAT) it was revealed that blazars, representing the most extreme radio-loud active galactic nuclei (AGN) population, dominate the census of the γ-ray sky, and a significant correlation was found between radio and γ-ray emission in the 0.1-100 GeV energy range. However, the possible connection between radio and very high energy (VHE, E> 0.1 TeV) emission still remains elusive, owing to the lack of a homogeneous coverage of the VHE sky. Aims: The main goal of this work is to quantify and assess the significance of a possible connection between the radio emission on parsec scale measured by the very long baseline interferometry (VLBI) and GeV-TeV γ-ray emission in blazars, which is a central issue for understanding blazar physics and the emission processes in these objects. Methods: We investigate the radio VLBI and high energy γ-ray emission by using two large and unbiased AGN samples extracted from the first and second Fermi-LAT catalogs of hard γ-ray sources detected above 10 GeV (1FHL) and 50 GeV (2FHL). For comparison, we perform the same correlation analysis by using the 0.1-300 GeV γ-ray energy flux provided by the third Fermi-LAT source catalog (3FGL). We assess the correlation's statistical significance by means of a method based on permutations of the luminosities, by taking into account the various observational biases, which may apparently enhance or spoil any intrinsic correlation. Results: We find that the correlation strength and significance depend on the γ-ray energy range, with a different behavior among the blazar sub-classes. Overall, the radio and γ-ray emission above 10 GeV turns out to be uncorrelated for the full samples and for all of the blazar sub-classes with the exception of high synchrotron peaked (HSP) objects, which show a strong and significant correlation. On the contrary, when 0.1-300 GeV γ-ray energies are considered, a strong and significant correlation is found for the full blazar sample as well as for all of the blazar sub-classes. Conclusions: We interpret and explain this correlation behavior within the framework of the blazar spectral energy distribution properties. In the most powerful blazars, which are in general of low synchrotron peaked type, the high energy emission component peaks at energies lower than those sampled by the LAT. On the contrary, in HSP blazars the part of the high energy spectrum affected by cooling effects is well beyond the energy range sampled by the LAT, showing a rising spectrum both in the 3FGL and 1FHL/2FHL energy ranges.

Probing dim point sources in the inner Milky Way using PCAT

NASA Astrophysics Data System (ADS)

Daylan, Tansu; Portillo, Stephen K. N.; Finkbeiner, Douglas P.

2017-01-01

Poisson regression of the Fermi-LAT data in the inner Milky Way reveals an extended gamma-ray excess. An important question is whether the signal is coming from a collection of unresolved point sources, possibly old recycled pulsars, or constitutes a truly diffuse emission component. Previous analyses have relied on non-Poissonian template fits or wavelet decomposition of the Fermi-LAT data, which find evidence for a population of dim point sources just below the 3FGL flux limit. In order to be able to draw conclusions about the flux distribution of point sources at the dim end, we employ a Bayesian trans-dimensional MCMC framework by taking samples from the space of catalogs consistent with the observed gamma-ray emission in the inner Milky Way. The software implementation, PCAT (Probabilistic Cataloger), is designed to efficiently explore that catalog space in the crowded field limit such as in the galactic plane, where the model PSF, point source positions and fluxes are highly degenerate. We thus generate fair realizations of the underlying MSP population in the inner galaxy and constrain the population characteristics such as the radial and flux distribution of such sources.

The effect of precipitation on measuring sea surface salinity from space

NASA Astrophysics Data System (ADS)

Jin, Xuchen; Pan, Delu; He, Xianqiang; Wang, Difeng; Zhu, Qiankun; Gong, Fang

2017-10-01

The sea surface salinity (SSS) can be measured from space by using L-band (1.4 GHz) microwave radiometers. The L-band has been chosen for its sensitivity of brightness temperature to the change of salinity. However, SSS remote sensing is still challenging due to the low sensitivity of brightness temperature to SSS variation: for the vertical polarization, the sensitivity is about 0.4 to 0.8 K/psu with different incident angles and sea surface temperature; for horizontal polarization, the sensitivity is about 0.2 to 0.6 K/psu. It means that we have to make radiometric measurements with accuracy better than 1K even for the best sensitivity of brightness temperature to SSS. Therefore, in order to retrieve SSS, the measured brightness temperature at the top of atmosphere (TOA) needs to be corrected for many sources of error. One main geophysical source of error comes from atmosphere. Currently, the atmospheric effect at L-band is usually corrected by absorption and emission model, which estimate the radiation absorbed and emitted by atmosphere. However, the radiation scattered by precipitation is neglected in absorption and emission models, which might be significant under heavy precipitation. In this paper, a vector radiative transfer model for coupled atmosphere and ocean systems with a rough surface is developed to simulate the brightness temperature at the TOA under different precipitations. The model is based on the adding-doubling method, which includes oceanic emission and reflection, atmospheric absorption and scattering. For the ocean system with a rough surface, an empirical emission model established by Gabarro and the isotropic Cox-Munk wave model considering shadowing effect are used to simulate the emission and reflection of sea surface. For the atmospheric attenuation, it is divided into two parts: For the rain layer, a Marshall-Palmer distribution is used and the scattering properties of the hydrometeors are calculated by Mie theory (the scattering hydrometeors are assumed to be spherical). For the other atmosphere layers, which are assumed to be clear sky, Liebe's millimeter wave propagation model (MPM93) is used to calculate the absorption coefficients of oxygen, water vapor, and cloud droplets. To simulate the change of brightness temperature caused by different rain rate (0-50 mm/h), we assume a 26-layer precipitation structure corresponding to NCEP FNL data. Our radiative transfer simulations showed that the brightness temperature at TOA can be influenced significantly by the heavy precipitation, the results indicate that the atmospheric attenuation of L-band at incidence angle of 42.5° should be a positive bias, and when rain rate rise up to 50 mm/h, the brightness temperature increases are close to 0.6 K and 0.8 K for horizontally and vertically polarized brightness temperature, respectively. Thus, in the case of heavy precipitation, the current absorption and emission model is not accurate enough to correct atmospheric effect, and a radiative transfer model which considers the effect of radiation scattering should be used.

A Dust-scattering Halo of 4U 1630–47 Observed with Chandra and Swift: New Constraints on the Source Distance

NASA Astrophysics Data System (ADS)

Kalemci, E.; Maccarone, T. J.; Tomsick, J. A.

2018-06-01

We have observed the Galactic black hole transient 4U 1630‑47 during the decay of its 2016 outburst with Chandra and Swift to investigate the properties of the dust-scattering halo created by the source. The scattering halo shows a structure that includes a bright ring between 80″ and 240″ surrounding the source, and a continuous distribution beyond 250″. An analysis of the 12CO J = 1–0 map and spectrum in the line of sight to the source indicates that a molecular cloud with a radial velocity of ‑79 km s‑1 (denoted MC ‑79) is the main scattering body that creates the bright ring. We found additional clouds in the line of sight, calculated their kinematic distances, and resolved the well known “near” and “far” distance ambiguity for most of the clouds. At the favored far-distance estimate of MC ‑79, the modeling of the surface brightness profile results in a distance to 4U 1630‑47 of 11.5 ± 0.3 kpc. If MC ‑79 is at the near distance, then 4U 1630‑47 is at 4.7 ± 0.3 kpc. Future Chandra, Swift, and submillimeter radio observations not only can resolve this ambiguity, but also would provide information regarding properties of dust and the distribution of all molecular clouds along the line of sight. Using the results of this study we also discuss the nature of this source and the reasons for the observation of an anomalously low soft state during the 2010 decay.

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

Hartemann, F V; Albert, F; Anderson, S G

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabledmore » by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).« less

An unusually strong Einstein ring in the radio source PKS1830 - 211

NASA Technical Reports Server (NTRS)

Jauncey, D. L.; Reynolds, J. E.; Tzioumis, A. K.; Murphy, D. W.; Preston, R. A.; Jones, D. L.; Meier, D. L.; Hoard, D. W.; Lobdell, E. T.; Skjerve, L.

1991-01-01

High-resolution radio images of PKS1830 - 211 are obtained to study the possibility that the double structure is a gravitationally lensed object. The VLBI observations, taken from interferometric radiotelescope networks, reveal an elliptical ring that connects two bright spots of similar composition. Because the lens and the lensed object are closely aligned, and because of the structure of the two spots, the source is concluded to be a radio Einstein ring. The source is found to be close to the galactic plane, and the lens and the lensed object are extragalactic. The source is also found to be unusually bright, suggesting that it is aligned with a bright background source or amplified by some mechanism related to a source that is not so bright.

The Herschel Bright Sources (HerBS): sample definition and SCUBA-2 observations

NASA Astrophysics Data System (ADS)

Bakx, Tom J. L. C.; Eales, S. A.; Negrello, M.; Smith, M. W. L.; Valiante, E.; Holland, W. S.; Baes, M.; Bourne, N.; Clements, D. L.; Dannerbauer, H.; De Zotti, G.; Dunne, L.; Dye, S.; Furlanetto, C.; Ivison, R. J.; Maddox, S.; Marchetti, L.; Michałowski, M. J.; Omont, A.; Oteo, I.; Wardlow, J. L.; van der Werf, P.; Yang, C.

2018-01-01

We present the Herschel Bright Sources (HerBS) sample, a sample of bright, high-redshift Herschel sources detected in the 616.4 deg2 Herschel Astrophysical Terahertz Large Area Survey. The HerBS sample contains 209 galaxies, selected with a 500 μm flux density greater than 80 mJy and an estimated redshift greater than 2. The sample consists of a combination of hyperluminous infrared galaxies and lensed ultraluminous infrared galaxies during the epoch of peak cosmic star formation. In this paper, we present Submillimetre Common-User Bolometer Array 2 (SCUBA-2) observations at 850 μm of 189 galaxies of the HerBS sample, 152 of these sources were detected. We fit a spectral template to the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) and 850 μm SCUBA-2 flux densities of 22 sources with spectroscopically determined redshifts, using a two-component modified blackbody spectrum as a template. We find a cold- and hot-dust temperature of 21.29_{-1.66}^{+1.35} and 45.80_{-3.48}^{+2.88} K, a cold-to-hot dust mass ratio of 26.62_{-6.74}^{+5.61} and a β of 1.83_{-0.28}^{+0.14}. The poor quality of the fit suggests that the sample of galaxies is too diverse to be explained by our simple model. Comparison of our sample to a galaxy evolution model indicates that the fraction of lenses are high. Out of the 152 SCUBA-2 detected galaxies, the model predicts 128.4 ± 2.1 of those galaxies to be lensed (84.5 per cent). The SPIRE 500 μm flux suggests that out of all 209 HerBS sources, we expect 158.1 ± 1.7 lensed sources, giving a total lensing fraction of 76 per cent.

Cosmic rays in the surroundings of SNR G35.6–0.4

DOE PAGES

Torres, Diego F.; Li, Hui; Chen, Yang; ...

2011-11-02

HESS J1858+020 is a TeV gamma-ray source that was reported to have no clearly catalogued counterpart at any wavelength. However, it has been recently proposed that this source is indirectly associated with the radio source, re-identified as a supernova remnant (SNR), G35.6–0.4. The latter has been found to be middle-aged (~30 kyr) and to have nearby molecular clouds (MCs). HESS J1858+020 was proposed to be the result of the interaction of protons accelerated in the SNR shell with target ions residing in the clouds. The Fermi Large Area Telescope (LAT) First Source Catalog does not list any source coincident withmore » the position of HESS J1858+020, but some lie close. Here, we analyse more than 2 years of data obtained with the Fermi-LAT for the region of interest, and consider whether it is indeed possible that the closest LAT source, 1FGL J1857.1+0212c, is related to HESS J1858+020. We conclude it is not, and we impose upper limits on the GeV emission originating from HESS J1858+020. Using a simplified 3D model for the cosmic ray propagation out from the shell of the SNR, we consider whether the interaction between SNR G35.6–0.4 and the MCs nearby could give rise to the TeV emission of HESS J1858+020 without producing a GeV counterpart. If so, the pair of SNR/TeV source with no GeV detection would be reminiscent of other similarly aged SNRs, such as some of the TeV hotspots near W28, for which cosmic ray diffusion may be used to explain their multifrequency phenomenology. Furthermore, for HESS J1858+020, we found that although the phase space in principle allows such a GeV–TeV non-correlation to appear, usual and/or observationally constrained values of the parameters (e.g., diffusion coefficients and cloud–SNR likely distances) would disfavour it.« less

Ultrabright continuously tunable terahertz-wave generation at room temperature

PubMed Central

Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

2014-01-01

The hottest frequency region in terms of research currently lies in the ‘frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm2, brightness temperature of ~1018 K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~1016 K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region. PMID:24898269

Ultrabright continuously tunable terahertz-wave generation at room temperature.

PubMed

Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

2014-06-05

The hottest frequency region in terms of research currently lies in the 'frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm(2), brightness temperature of ~10(18) K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~10(16) K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region.

Spatially Resolving the Very High Energy Emission from MGRO J2019+37 with VERITAS

NASA Astrophysics Data System (ADS)

Aliu, E.; Aune, T.; Behera, B.; Beilicke, M.; Benbow, W.; Berger, K.; Bird, R.; Bouvier, A.; Buckley, J. H.; Bugaev, V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dumm, J.; Dwarkadas, V. V.; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Fortin, P.; Fortson, L.; Furniss, A.; Galante, N.; Gillanders, G. H.; Gotthelf, E. V.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Hanna, D.; Holder, J.; Hughes, G.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kargaltsev, O.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krennrich, F.; Lang, M. J.; Madhavan, A. S.; Maier, G.; McArthur, S.; McCann, A.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Pandel, D.; Park, N.; Pohl, M.; Popkow, A.; Prokoph, H.; Quinn, J.; Ragan, K.; Rajotte, J.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Roberts, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Vincent, S.; Wakely, S. P.; Weinstein, A.; Welsing, R.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

2014-06-01

We present very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended (~2°) unidentified Milagro source is located toward the rich star formation region Cygnus-X. MGRO J2019+37 is resolved into two VERITAS sources. The faint, point-like source VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) with no evidence of a supernova remnant shell at the present time. Its spectrum is well fit in the 0.65-10 TeV energy range by a power-law model with photon index 2.3 ± 0.4. VER J2019+378 is a bright extended (~1°) source that likely accounts for the bulk of the Milagro emission and is notably coincident with PSR J2021+3651 and the star formation region Sh 2-104. Its spectrum in the range 1-30 TeV is well fit with a power-law model of photon index 1.75 ± 0.3, among the hardest values measured in the VHE band, comparable to that observed near Vela-X. We explore the unusual spectrum and morphology in the radio and X-ray bands to constrain possible emission mechanisms for this source.

Limits to the lunar atmosphere

NASA Astrophysics Data System (ADS)

Morgan, T. H.; Shemansky, D. E.

1991-02-01

Apollo UV spectrometer experiment set limits on the density of oxygen of less than 500/cu cm, and the Apollo Lunar Atmospheric Composition Experiment data imply a value less than 50/cu cm above the subsolar point. These limits are surprisingly small relative to the measured value for sodium. A simple consideration of sources and sinks predicts significantly greater densities of oxygen. It is possible but doubtful that the Apollo measurements occurred during an epoch in which source rates were small. A preferential loss process for oxygen on the darkside of the moon is considered in which ionization by electron capture in surface collisions leads to escape through acceleration in the local electric field. Cold trapping in permanently shadowed regions as a net sink is considered and discounted, but the episodic nature of cometary insertion may allow formation of ice layers which act as a stabilized source of OH. On the basis of an assumed meteoroid impact source, a possible emission brightness of 50 R in the OH(A - X)(0,0) band above the lunar bright limb is predicted.

Limits to the lunar atmosphere

NASA Technical Reports Server (NTRS)

Morgan, T. H.; Shemansky, D. E.

1991-01-01

Apollo UV spectrometer experiment set limits on the density of oxygen of less than 500/cu cm, and the Apollo Lunar Atmospheric Composition Experiment data imply a value less than 50/cu cm above the subsolar point. These limits are surprisingly small relative to the measured value for sodium. A simple consideration of sources and sinks predicts significantly greater densities of oxygen. It is possible but doubtful that the Apollo measurements occurred during an epoch in which source rates were small. A preferential loss process for oxygen on the darkside of the moon is considered in which ionization by electron capture in surface collisions leads to escape through acceleration in the local electric field. Cold trapping in permanently shadowed regions as a net sink is considered and discounted, but the episodic nature of cometary insertion may allow formation of ice layers which act as a stabilized source of OH. On the basis of an assumed meteoroid impact source, a possible emission brightness of 50 R in the OH(A - X)(0,0) band above the lunar bright limb is predicted.

A synthetic neural cell adhesion molecule mimetic peptide promotes synaptogenesis, enhances presynaptic function, and facilitates memory consolidation.

PubMed

Cambon, Karine; Hansen, Stine M; Venero, Cesar; Herrero, A Isabel; Skibo, Galina; Berezin, Vladimir; Bock, Elisabeth; Sandi, Carmen

2004-04-28

The neural cell adhesion molecule (NCAM) plays a critical role in development and plasticity of the nervous system and is involved in the mechanisms of learning and memory. Here, we show that intracerebroventricular administration of the FG loop (FGL), a synthetic 15 amino acid peptide corresponding to the binding site of NCAM for the fibroblast growth factor receptor 1 (FGFR1), immediately after training rats in fear conditioning or water maze learning, induced a long-lasting improvement of memory. In primary cultures of hippocampal neurons, FGL enhanced the presynaptic function through activation of FGFR1 and promoted synapse formation. These results provide the first evidence for a memory-facilitating effect resulting from a treatment that mimics NCAM function. They suggest that increased efficacy of synaptic transmission and formation of new synapses probably mediate the cognition-enhancing properties displayed by the peptide.

Periodic Emission from the Gamma-Ray Binary 1FGL J1018.6-5856

DOE PAGES

Ackermann, M.

2012-01-12

Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable X-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGLmore » J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.« less

A Multi-Wavelength Study of the X-Ray Sources in the NGC 5018

NASA Technical Reports Server (NTRS)

Ghosh, Kajal K.; Swartz, Douglas A.; Tennant, Allyn F.; Wu, Kinwah; Saripalli, Lakshmi

2004-01-01

The E3 giant elliptical galaxy NGC-5018 was observed with the cxo X-ray Observatory's Advanced CCD Imaging Spectrometer for 30-h on 14 April 2001. Results of analysis of these X-ray data as well as of complementary optical, infrared, and radio data are reported. Seven X-ray point sources, including the nucleus, were detected. If they are intrinsic to NGC-5018, then all six non-nuclear sources have luminosities exceeding 10(exp 39)-ergl in the 0.5-8.0-keV energy band; placing them in the class of Ultra- luminous X-ray sources. Comparison of X-ray source positions to archival Hubble Space Telescope/Wide Field Planetary Camera 2 (hst/WFPC2) images reveal four of the six non-nuclear sources are spatially--coincident with bright, M$(sub V)LA -8.6 mag, objects. These four objects have optical magnitudes and (V-I) colors consistent with globular clusters in NGC-5018. However, one of these objects was observed to vary by siml mag in both V and I between observations taken 28 July 1997 and 04 Feb 1999 indicating this source is a background active galactic nucleus (AGN). The nature of the other three optically-bright objects cannot be determined from the available optical data but all have X-ray-to-optical flux ratios consistent with background AGNs. Strong, unpolarized, radio emission has been detected from another of the optically-bright counterparts. It displays an inverted radio spectrum and is the most absorbed of the seven sources in the X-ray band. It, too, is most readily explained as a background AGN, though alternative explanations cannot be ruled out. Extended X-ray emission is detected within a siml5 arcsec radius of the galaxy center at a luminosity of sim lO(exp 40)-ergl in the X-ray band. Its thermal X-ray spectrum (kT sim0.4-keV) and its spatial coincidence with strong H(alpha) emission are consistent with a hot gas origin. The nucleus itself is a weak X-ray source, LA-5 times 10(exp 39)-ergl, but displays a radio spectrum typical of AGN.

Cyclotron Line in Solar Microwave Radiation by Radio Telescope RATAN-600 Observations of the Solar Active Region NOAA 12182

NASA Astrophysics Data System (ADS)

Peterova, N. G.; Topchilo, N. A.

2017-12-01

This paper presents the results of observation of a rare phenomenon—a narrowband increase in the brightness of cyclotron radiation of one of the structural details of a radio source located in the solar corona above the solar active region NOAA 12182 in October 2014 at a frequency of 4.2 ± 0.1 GHz. The brightness of radiation in the maximum of the phenomenon has reached 10 MK; its duration was equal to 3 s. The exact location of the source of the narrowband cyclotron radiation is indicated: it is a corona above a fragmented (4-nuclear) sunspot, on which a small UV flare loop was closed.

iPTF discovery and identification of bright transients

NASA Astrophysics Data System (ADS)

Adams, Scott; Karamehmetoglu, Emir; Roy, Rupak; Neill, James D.; Walters, Richard; Cook, Dave; Kupfer, Thomas; Cannella, Chris; Blagorodnova, Nadejda; Yan, Lin; Kasliwal, Mansi; Kulkarni, Shri

2017-02-01

The intermediate Palomar Transient Factory (ATel #4807) reports the discovery of the following bright transients. We report as ATel alerts all objects brighter than 19 mag. Our discoveries are reported in two filters: sdss-g and Mould-I, denoted as g and I. All magnitudes are obtained using difference image photometry based on the PTFIDE pipeline described in Masci et al. 2016.Our automated candidate vetting to distinguish a real astrophysical source (1.0) from bogus artifacts (0.0) is powered by three generations of machine learning algorithms: RB2 (Brink et al. 2013MNRAS.435.1047B), RB4 (Rebbapragada et al. 2015AAS...22543402R), and RB5 (Wozniak et al. 2013AAS...22143105W).

Laser ion source for high brightness heavy ion beam

DOE PAGES

Okamura, M.

2016-09-01

A laser ion source is known as a high current high charge state heavy ion source. But, we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. Furthermore, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory in 2014. Now most of all the solid based heavy ions are being provided from the laser ion sourcemore » for regular operation.« less

High-resolution maps of Jupiter at five microns.

NASA Technical Reports Server (NTRS)

Keay, C. S. L.; Low, F. J.; Rieke, G. H.; Minton, R. B.

1973-01-01

The distribution of 5-micron radiation, emitted from a large number of discrete sources from Jupiter, was observed during the 1972 apparition. These sources are less bright than those observed by Westphal (1969). At least 50 discrete sources having brightness temperatures exceeding 227 K were revealed which were mainly located within three narrow-latitude bands. Strong correlation exists between the 5-micron brightness temperatures of Jovian features and their colors as recorded photographically.

Bright nanoscale source of deterministic entangled photon pairs violating Bell's inequality.

PubMed

Jöns, Klaus D; Schweickert, Lucas; Versteegh, Marijn A M; Dalacu, Dan; Poole, Philip J; Gulinatti, Angelo; Giudice, Andrea; Zwiller, Val; Reimer, Michael E

2017-05-10

Global, secure quantum channels will require efficient distribution of entangled photons. Long distance, low-loss interconnects can only be realized using photons as quantum information carriers. However, a quantum light source combining both high qubit fidelity and on-demand bright emission has proven elusive. Here, we show a bright photonic nanostructure generating polarization-entangled photon pairs that strongly violates Bell's inequality. A highly symmetric InAsP quantum dot generating entangled photons is encapsulated in a tapered nanowire waveguide to ensure directional emission and efficient light extraction. We collect ~200 kHz entangled photon pairs at the first lens under 80 MHz pulsed excitation, which is a 20 times enhancement as compared to a bare quantum dot without a photonic nanostructure. The performed Bell test using the Clauser-Horne-Shimony-Holt inequality reveals a clear violation (S CHSH  > 2) by up to 9.3 standard deviations. By using a novel quasi-resonant excitation scheme at the wurtzite InP nanowire resonance to reduce multi-photon emission, the entanglement fidelity (F = 0.817 ± 0.002) is further enhanced without temporal post-selection, allowing for the violation of Bell's inequality in the rectilinear-circular basis by 25 standard deviations. Our results on nanowire-based quantum light sources highlight their potential application in secure data communication utilizing measurement-device-independent quantum key distribution and quantum repeater protocols.

Interferometric Monitoring of Gamma-Ray Bright AGNs: S5 0716+714

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

Lee, Jee Won; Lee, Sang-Sung; Hodgson, Jeffrey A.

We present the results of very long baseline interferometry (VLBI) observations of gamma-ray bright blazar S5 0716+714 using the Korean VLBI Network (KVN) at the 22, 43, 86, and 129 GHz bands, as part of the Interferometric Monitoring of Gamma-ray Bright active galactic nuclei (iMOGABA) KVN key science program. Observations were conducted in 29 sessions from 2013 January 16 to 2016 March 1, with the source being detected and imaged at all available frequencies. In all epochs, the source was compact on the milliarcsecond scale, yielding a compact VLBI core dominating the synchrotron emission on these scales. Based on themore » multiwavelength data between 15 GHz (Owens Valley Radio Observatory) and 230 GHz (Submillimeter Array), we found that the source shows multiple prominent enhancements of the flux density at the centimeter (cm) and millimeter (mm) wavelengths, with mm enhancements leading cm enhancements by −16 ± 8 days. The turnover frequency was found to vary between 21 and 69 GHz during our observations. By assuming a synchrotron self-absorption model for the relativistic jet emission in S5 0716+714, we found the magnetic field strength in the mas emission region to be ≤5 mG during the observing period, yielding a weighted mean of 1.0 ± 0.6 mG for higher turnover frequencies (e.g., >45 GHz).« less

Automated detection of very Low Surface Brightness galaxies in the Virgo Cluster

NASA Astrophysics Data System (ADS)

Prole, D. J.; Davies, J. I.; Keenan, O. C.; Davies, L. J. M.

2018-04-01

We report the automatic detection of a new sample of very low surface brightness (LSB) galaxies, likely members of the Virgo cluster. We introduce our new software, DeepScan, that has been designed specifically to detect extended LSB features automatically using the DBSCAN algorithm. We demonstrate the technique by applying it over a 5 degree2 portion of the Next-Generation Virgo Survey (NGVS) data to reveal 53 low surface brightness galaxies that are candidate cluster members based on their sizes and colours. 30 of these sources are new detections despite the region being searched specifically for LSB galaxies previously. Our final sample contains galaxies with 26.0 ≤ ⟨μe⟩ ≤ 28.5 and 19 ≤ mg ≤ 21, making them some of the faintest known in Virgo. The majority of them have colours consistent with the red sequence, and have a mean stellar mass of 106.3 ± 0.5M⊙ assuming cluster membership. After using ProFit to fit Sérsic profiles to our detections, none of the new sources have effective radii larger than 1.5 Kpc and do not meet the criteria for ultra-diffuse galaxy (UDG) classification, so we classify them as ultra-faint dwarfs.

Three Bright X-ray Sources in NGC 1313

NASA Astrophysics Data System (ADS)

Colbert, E.; Petre, R.; Schlegel, E.

1992-12-01

Three bright X-ray sources were detected in a recent (April/May 1991) ROSAT PSPC observation of the nearby (D ~ 4.5 Mpc) face--on barred spiral galaxy NGC 1313. Two of the sources were at positions coincident with X-ray sources detected by Fabbiano & Trinchieri (ApJ 315, 1987) in a previous (Jan 1980) Einstein IPC observation. The position of the brightest Einstein source is near the center of NGC 1313, and the second Einstein source is ~ 7' south of the ``nuclear'' source, in the outskirts of the spiral arms. A third bright X-ray source was detected in the ROSAT observation ~ 7' southwest of the ``nuclear'' source. We present X-ray spectra and X-ray images for the three bright sources found in the ROSAT observation of NGC 1313, and compare with previous Einstein results. Spectral analysis of these sources require them to have very large soft X-ray luminosities ( ~ 10(40) erg s(-1) ) when compared with typical X-ray sources in our Galaxy. Feasible explanations for the X-ray emission are presented. The third X-ray source is positively identified with the recently discovered (Ryder et. al., ApJ 1992) peculiar type-II supernova 1978K.

Ultrahigh 6D-brightness electron beams for the light sources of the next generation

NASA Astrophysics Data System (ADS)

Habib, Fahim; Manahan, Grace G.; Scherkl, Paul; Heinemann, Thomas; Sheng, Z. M.; Bruhwiler, D. L.; Cary, J. R.; Rosenzweig, J. B.; Hidding, Bernhard

2017-10-01

The plasma photocathode mechanism (aka Trojan Horse) enables a path towards electron beams with nm-level normalized emittance and kA range peak currents, hence ultrahigh 5D-brightness. This ultrahigh 5D-brightness beams hold great prospects to realize laboratory scale free-electron-lasers. However, the GV/m-accelerating gradient in plasma accelerators leads to substantial energy chirp and spread. The large energy spread is a major show-stopper towards key application such as the free-electron-laser. Here we present a novel method for energy chirp compensation which takes advantage of tailored beam loading due to a second ``escort'' bunch released via plasma photocathode. The escort bunch reverses the accelerating field locally at the trapping position of the ultrahigh 5D-brightness beam. This induces a counter-clockwise rotation within the longitudinal phase space and allows to compensate the chirp completely. Analytical scaling predicts energy spread values below 0.01 percentage level. Ultrahigh 5D-brightness combined with minimized energy spread opens a path towards witness beams with unprecedented ultrahigh 6D-brightness.

The infrared counterpart of GX 13 + 1

NASA Technical Reports Server (NTRS)

Garcia, M. R.; Grindlay, J. E.; Bailyn, C. D.; Pipher, J. L.; Shure, M. A.; Woodward, C. E.

1992-01-01

A bright (K = 12) IR source is discovered which is likely the counterpart to the bright galactic-bulge X-ray source GX 13 + 1. Observations with the MMT IR photometer and the Rochester IR Array camera at the IRTF allow determination of the source position to about 0.7 arcsec, allow the IR colors to be measured, and show no variability on a 1-yr timescale. Four possible sources for the IR emission are considered and it is most likely due to a K-giant secondary. The discovery of a late-type giant secondary in GX 13 + 1 is contrary to the expectation that low-mass X-ray binaries which show quasi-periodic oscillations (QPO) have giant companions, while those which do not show QPO (like GX 13 + 1) have dwarf secondaries. The relation between the size of the scattered X-ray halo and the Av inferred from the IR observations is compared to that found in other X-ray sources.

Overview of Mono-Energetic Gamma-Ray Sources and Applications

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

Hartemann, Fred; /LLNL, Livermore; Albert, Felicie

2012-06-25

Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable Mono-Energetic Gamma-ray (MEGa-ray) source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC NAL will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energymore » range via Compton scattering. This MEGaray source will be used to excite nuclear resonance fluorescence in various isotopes. Applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications, including nuclear resonance fluorescence.« less

A highly embedded protostar in SFO 18: IRAS 05417+0907

NASA Astrophysics Data System (ADS)

Saha, Piyali; Gopinathan, Maheswar; Puravankara, Manoj; Sharma, Neha; Soam, Archana

2018-04-01

Bright-rimmed clouds, located at the periphery of relatively evolved HIT regions, are considered to be the sites of star formation possibly triggered by the implosion caused due to the ionizing radiation from nearby massive stars. SFO 18 is one such region showing a bright-rim on the side facing the 0-type star, A Ori. A point source, IRAS 05417+0907, is detected towards the high density region of the cloud. A molecular outflow has been found to be associated with the source. The outflow is directed towards a Herbig-Haro object, HH 175. From the Spitzer and WISE observations, we show evidence of a physical connection between the molecular outflow, IRAS 05417+0907 and the HH object. The spectral energy distribution constructed using multi-wavelength data shows that the point source is most likely a highly embedded protostar.

The near-infrared properties of compact binary systems

NASA Astrophysics Data System (ADS)

Froning, Cynthia Suzanne

I present H- and K-band light curves of the dwarf nova cataclysmic variable (CV), IP Peg, and the novalike CV, RW Tri, and an H-band light curve of the novalike CV, SW Sex. All three systems showed contributions from the late-type secondary star and the accretion disk, including a primary eclipse of the accretion disk by the secondary star and a secondary eclipse of the star by the disk. The ellipsoidal variations of the secondary star in IP Peg were modeled and subtracted from the data. The subtracted light curves show a pronounced double-hump variation, resembling those seen in the dwarf novae WZ Sge and AL Com. The primary eclipse was modeled using maximum entropy disk mapping techniques. The accretion disk has a flat intensity distribution and a low brightness temperature (Tbr ~= 3000-4000 K). Superimposed on the face of the disk is the bright spot, where the mass accretion stream impacts the disk; the position of the bright spot is different from the range of positions seen at visible wavelengths. The near-infrared accretion disk flux is dominated by optically thin emission. The eclipse depth is too shallow to be caused by a fully opaque accretion disk. The NIR light curves in RW Tri show a deep primary eclipse of the accretion disk, ellipsoidal variations from the secondary star, a secondary eclipse, and strong flickering in the disk flux. The depth of the secondary eclipse indicates that the accretion disk is opaque. The light curve also has a hump extending from φ = 0.1-0.9 which was successfully modeled as flux from the inner face of the secondary star when heated by a ~0.2 L Lsolar source. The radial brightness temperature profile of the outer disk is consistent with models of a disk in steady-state for a mass transfer rate of M~=5×10- 10 Msolaryr- 1 . At small disk radii, however, the brightness temperature profile is flatter than the steady-state model. The H-band light curve of SW Sex is dominated by emission from the accretion disk. As in RW Tri, the light curve has a hump outside of primary eclipse which was modeled as flux from the secondary star when irradiated by a 0.2-0.3 Lsolar source. The light curve has a dip at φ = 0.5 which is consistent with an eclipse of the irradiated face of the secondary star by an opaque accretion disk. The accretion disk has a brightness temperature profile much flatter than the theoretical profile of a steady- state disk. The disk is asymmetric, with the front of the disk (the side facing the secondary star at mid-eclipse) hotter than the back. The bright spot, which appears in visible disk maps of SW Sex, is not seen in the NIR light curve. I also present H-band light curves of the X-ray binary system, A0620-00, and NIR spectra of two X-ray binaries, CI Cam, and the relativistic jet source, SS 433. (Abstract shortened by UMI.)

Unidentified point sources in the IRAS minisurvey

NASA Technical Reports Server (NTRS)

Houck, J. R.; Soifer, B. T.; Neugebauer, G.; Beichman, C. A.; Aumann, H. H.; Clegg, P. E.; Gillett, F. C.; Habing, H. J.; Hauser, M. G.; Low, F. J.

1984-01-01

Nine bright, point-like 60 micron sources have been selected from the sample of 8709 sources in the IRAS minisurvey. These sources have no counterparts in a variety of catalogs of nonstellar objects. Four objects have no visible counterparts, while five have faint stellar objects visible in the error ellipse. These sources do not resemble objects previously known to be bright infrared sources.

VizieR Online Data Catalog: Gamma-ray bright blazars spectrophotometry (Williamson+, 2014)

NASA Astrophysics Data System (ADS)

Williamson, K. E.; Jorstad, S. G.; Marscher, A. P.; Larionov, V. M.; Smith, P. S.; Agudo, I.; Arkharov, A. A.; Blinov, D. A.; Casadio, C.; Efimova, N. V.; Gomez, J. L.; Hagen-Thorn, V. A.; Joshi, M.; Konstantinova, T. S.; Kopatskaya, E. N.; Larionova, E. G.; Larionova, L. V.; Malmrose, M. P.; McHardy, I. M.; Molina, S. N.; Morozova, D. A.; Schmidt, G. D.; Taylor, B. W.; Troitsky, I. S.

2017-03-01

Since 2007, we have been collecting multi-waveband fluxes, polarization measurements, and radio images of blazars to provide the data for understanding the physics of the jets (see, e.g., Marscher 2012, arXiv:1201.5402). This study includes 28 of the original 30 objects selected for the monitoring campaign, confirmed as γ-ray sources by EGRET (Energetic γ-Ray Experiment Telescope) on the Compton Gamma Ray Observatory, have an R-band brightness exceeding 18 mag (bright enough for optical polarization measurements at a 1-2 m class optical telescope without needing excessive amounts of telescope time), exceed 0.5 Jy at 43 GHz, and have a declination accessible to the collaboration's observatories (> - 30°). Three additional BL Lacs (1055+018, 1308+326, and 1749+096) and two FSRQs (3C345 and 3C446) included in this analysis were among those added when they were detected as γ-ray sources by the Fermi LAT (Abdo et al. 2009, J/ApJ/700/597). (4 data files).

The Einstein@Home Gamma-ray Pulsar Survey. II. Source Selection, Spectral Analysis, and Multiwavelength Follow-up

NASA Astrophysics Data System (ADS)

Wu, J.; Clark, C. J.; Pletsch, H. J.; Guillemot, L.; Johnson, T. J.; Torne, P.; Champion, D. J.; Deneva, J.; Ray, P. S.; Salvetti, D.; Kramer, M.; Aulbert, C.; Beer, C.; Bhattacharyya, B.; Bock, O.; Camilo, F.; Cognard, I.; Cuéllar, A.; Eggenstein, H. B.; Fehrmann, H.; Ferrara, E. C.; Kerr, M.; Machenschalk, B.; Ransom, S. M.; Sanpa-Arsa, S.; Wood, K.

2018-02-01

We report on the analysis of 13 gamma-ray pulsars discovered in the Einstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8 data. The 13 new gamma-ray pulsars were discovered by searching 118 unassociated LAT sources from the third LAT source catalog (3FGL), selected using the Gaussian Mixture Model machine-learning algorithm on the basis of their gamma-ray emission properties being suggestive of pulsar magnetospheric emission. The new gamma-ray pulsars have pulse profiles and spectral properties similar to those of previously detected young gamma-ray pulsars. Follow-up radio observations have revealed faint radio pulsations from two of the newly discovered pulsars and enabled us to derive upper limits on the radio emission from the others, demonstrating that they are likely radio-quiet gamma-ray pulsars. We also present results from modeling the gamma-ray pulse profiles and radio profiles, if available, using different geometric emission models of pulsars. The high discovery rate of this survey, despite the increasing difficulty of blind pulsar searches in gamma rays, suggests that new systematic surveys such as presented in this article should be continued when new LAT source catalogs become available.

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

Effects of 6-Weeks High-Intensity Interval Training in Schoolchildren with Insulin Resistance: Influence of Biological Maturation on Metabolic, Body Composition, Cardiovascular and Performance Non-responses

PubMed Central

Alvarez, Cristian; Ramírez-Campillo, Rodrigo; Ramírez-Vélez, Robinson; Izquierdo, Mikel

2017-01-01

Background: Previous studies have observed significant heterogeneity in the magnitude of change in measures of metabolic response to exercise training. There are a lack of studies examining the prevalence of non-responders (NRs) in children while considering other potential environmental factors involved such as biological maturation. Aim: To compare the effects and prevalence of NRs to improve the insulin resistance level (by HOMA-IR), as well as to other anthropometric, cardiovascular, and performance co-variables, between early (EM) and normal maturation (NM) in insulin-resistance schoolchildren after 6-weeks of HIIT. Methods: Sedentary children (age 11.4 ± 1.7 years) were randomized to either HIIT-EM group (n = 12) or HIIT-NM group (n = 17). Fasting glucose (FGL), fasting insulin (FINS) and homeostasis model assessment of insulin resistant (HOMA-IR) were assessed as the main outcomes, as well as the body composition [body mass, body mass index (BMI), waist circumference (WC), and tricipital (TSF), suprailiac (SSF) and abdominal skinfold (AbdSF)], cardiovascular systolic (SBP) and diastolic blood pressure (DBP), and muscular performance [one-repetition maximum strength leg-extension (1RMLE) and upper row (1RMUR) tests] co-variables were assessed before and after intervention. Responders or NRs to training were defined as a change in the typical error method from baseline to follow-up for the main outcomes and co-variables. Results: There were no significant differences between groups in the prevalence of NRs based on FGL, FINS, and HOMA-IR. There were significant differences in NRs prevalence to decrease co-variables body mass (HIIT-EM 66.6% vs. HIIT-NM 35.2%) and SBP (HIIT-EM 41.6% vs. HIIT-NM 70.5%). A high risk [based on odds ratios (OR)] of NRs cases was detected for FGL, OR = 3.2 (0.2 to 5.6), and HOMA-IR, OR = 3.2 (0.2 to 6.0). Additionally, both HIIT-EM and HIIT-NM groups showed significant decreases (P < 0.05) in TSF, SSF, and AbdSF skinfold, and similar decreases in fasting insulin and HOMA-IR. The HIIT-EM group showed significant decreases in SBP. The HIIT-NM group showed significant increases in 1RMLE and 1RMUR. A large effect size was observed for pre-post changes in TSF in both groups, as well as in SSF in the HIIT-NM group. Conclusion: Although there were no differences in the prevalence of NRs to metabolic variables between groups of insulin resistance schoolchildren of different maturation starting, other NRs differences were found to body mass and systolic BP, suggesting that anthropometric and cardiovascular parameters can be playing a role in the NRs prevalence after HIIT. These results were displayed with several metabolic, body composition, blood pressure, and performance improvements independent of an early/normal maturation or the prevalence of NRs. PMID:28706490

Effects of 6-Weeks High-Intensity Interval Training in Schoolchildren with Insulin Resistance: Influence of Biological Maturation on Metabolic, Body Composition, Cardiovascular and Performance Non-responses.

PubMed

Alvarez, Cristian; Ramírez-Campillo, Rodrigo; Ramírez-Vélez, Robinson; Izquierdo, Mikel

2017-01-01

Background: Previous studies have observed significant heterogeneity in the magnitude of change in measures of metabolic response to exercise training. There are a lack of studies examining the prevalence of non-responders (NRs) in children while considering other potential environmental factors involved such as biological maturation. Aim: To compare the effects and prevalence of NRs to improve the insulin resistance level (by HOMA-IR), as well as to other anthropometric, cardiovascular, and performance co-variables, between early (EM) and normal maturation (NM) in insulin-resistance schoolchildren after 6-weeks of HIIT. Methods: Sedentary children (age 11.4 ± 1.7 years) were randomized to either HIIT-EM group ( n = 12) or HIIT-NM group ( n = 17). Fasting glucose (FGL), fasting insulin (FINS) and homeostasis model assessment of insulin resistant (HOMA-IR) were assessed as the main outcomes, as well as the body composition [body mass, body mass index (BMI), waist circumference (WC), and tricipital (TSF), suprailiac (SSF) and abdominal skinfold (AbdSF)], cardiovascular systolic (SBP) and diastolic blood pressure (DBP), and muscular performance [one-repetition maximum strength leg-extension (1RM LE ) and upper row (1RM UR ) tests] co-variables were assessed before and after intervention. Responders or NRs to training were defined as a change in the typical error method from baseline to follow-up for the main outcomes and co-variables. Results: There were no significant differences between groups in the prevalence of NRs based on FGL, FINS, and HOMA-IR. There were significant differences in NRs prevalence to decrease co-variables body mass (HIIT-EM 66.6% vs. HIIT-NM 35.2%) and SBP (HIIT-EM 41.6% vs. HIIT-NM 70.5%). A high risk [based on odds ratios (OR)] of NRs cases was detected for FGL, OR = 3.2 (0.2 to 5.6), and HOMA-IR, OR = 3.2 (0.2 to 6.0). Additionally, both HIIT-EM and HIIT-NM groups showed significant decreases ( P < 0.05) in TSF, SSF, and AbdSF skinfold, and similar decreases in fasting insulin and HOMA-IR. The HIIT-EM group showed significant decreases in SBP. The HIIT-NM group showed significant increases in 1RM LE and 1RM UR . A large effect size was observed for pre-post changes in TSF in both groups, as well as in SSF in the HIIT-NM group. Conclusion: Although there were no differences in the prevalence of NRs to metabolic variables between groups of insulin resistance schoolchildren of different maturation starting, other NRs differences were found to body mass and systolic BP, suggesting that anthropometric and cardiovascular parameters can be playing a role in the NRs prevalence after HIIT. These results were displayed with several metabolic, body composition, blood pressure, and performance improvements independent of an early/normal maturation or the prevalence of NRs.

The Position/Structure Stability of Four ICRF2 Sources

NASA Technical Reports Server (NTRS)

Fomalont, Ed; Johnston, Kenneth; Fey, Alan; Boboltz, Dave; Oyama, Tomoaki; Honma, Mareki

2010-01-01

Four compact radio sources in the International Celestial Reference Frame (ICRF2) catalog were observed using phase referencing with the VLBA at 43, 23, and 8.6-GHz, and with VERA at 23-GHz over a one-year period. The goal was to determine the stability of the radio cores and to assess structure effects associated with positions in the ICRF2. Conclusions are: (1) 43-GHz VLBI high-resolution observations are often needed to determine the location of the radio core. (2) Over the observing period, the relative positions among the four radio cores were constant to 0.02 mas, suggesting that once the true radio core is identified, it remains stationary in the sky to this accuracy. (3) The emission in 0556+238, one of the four sources investigated and one of the 295 ICRF2 defining sources, was dominated by a strong component near the core and moved 0.1 mas during the year. (4) Comparison of the VLBA images at 43, 23, and 8.6-GHz with the ICRF2 positions suggests that the 8-GHz structure is often dominated by a bright non-core component. The measured ICRF2 position can be displaced more than 0.5 mas from the radio core and partake in the motion of the bright jet component.

PN-CCD camera for XMM: performance of high time resolution/bright source operating modes

NASA Astrophysics Data System (ADS)

Kendziorra, Eckhard; Bihler, Edgar; Grubmiller, Willy; Kretschmar, Baerbel; Kuster, Markus; Pflueger, Bernhard; Staubert, Ruediger; Braeuninger, Heinrich W.; Briel, Ulrich G.; Meidinger, Norbert; Pfeffermann, Elmar; Reppin, Claus; Stoetter, Diana; Strueder, Lothar; Holl, Peter; Kemmer, Josef; Soltau, Heike; von Zanthier, Christoph

1997-10-01

The pn-CCD camera is developed as one of the focal plane instruments for the European photon imaging camera (EPIC) on board the x-ray multi mirror (XMM) mission to be launched in 1999. The detector consists of four quadrants of three pn-CCDs each, which are integrated on one silicon wafer. Each CCD has 200 by 64 pixels (150 micrometer by 150 micrometers) with 280 micrometers depletion depth. One CCD of a quadrant is read out at a time, while the four quadrants can be processed independently of each other. In standard imaging mode the CCDs are read out sequentially every 70 ms. Observations of point sources brighter than 1 mCrab will be effected by photon pile- up. However, special operating modes can be used to observe bright sources up to 150 mCrab in timing mode with 30 microseconds time resolution and very bright sources up to several crab in burst mode with 7 microseconds time resolution. We have tested one quadrant of the EPIC pn-CCD camera at line energies from 0.52 keV to 17.4 keV at the long beam test facility Panter in the focus of the qualification mirror module for XMM. In order to test the time resolution of the system, a mechanical chopper was used to periodically modulate the beam intensity. Pulse periods down to 0.7 ms were generated. This paper describes the performance of the pn-CCD detector in timing and burst readout modes with special emphasis on energy and time resolution.

Eclipse studies of the dwarf nova EX Draconis

NASA Astrophysics Data System (ADS)

Baptista, R.; Catalán, M. S.; Costa, L.

2000-08-01

We report on V and R high-speed photometry of the dwarf nova EX Draconis (EX Dra) in quiescence and in outburst. The analysis of the outburst light curves indicates that the outbursts do not start in the outer disc regions. The disc expands during the rise to maximum and shrinks during decline and along the following quiescent period. The decrease in brightness at the later stages of the outburst is due to the fading of the light from the inner disc regions. At the end of two outbursts the system was seen to go through a phase of lower brightness, characterized by an out-of-eclipse level ~=15 per cent lower than the typical quiescent level and by the fairly symmetric eclipse of a compact source at disc centre with little evidence of a bright spot at disc rim. New eclipse timings were measured from the light curves taken in quiescence and a revised ephemeris was derived. The residuals with respect to the linear ephemeris are well described by a sinusoid of amplitude 1.2min and period ~=4yr and are possibly related to a solar-like magnetic activity cycle in the secondary star. Eclipse phases of the compact central source and of the bright spot were used to derive the geometry of the binary. By constraining the gas stream trajectory to pass through the observed position of the bright spot, we find q=0.72+/-0.06 and i85+3-2 degrees. The binary parameters were estimated by combining the measured mass ratio with the assumption that the secondary star obeys an empirical main-sequence mass-radius relation. We find M1=0.75+/-0.15Msolar and M2=0.54+/-0.10Msolar. The results indicate that the white dwarf at disc centre is surrounded by an extended and variable atmosphere or boundary layer of at least three times its radius and a temperature of T~=28000K. The fluxes at mid-eclipse yield an upper limit to the contribution of the secondary star and lead to a lower limit photometric parallax distance of D=290+/-80pc. The fluxes of the secondary star are well-matched by those of a M0+/-2 main-sequence star.

Optimization of Compton Source Performance through Electron Beam Shaping

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

Malyzhenkov, Alexander; Yampolsky, Nikolai

2016-09-26

We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a waymore » so that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary.« less

Picosecond excimer laser-plasma x-ray source for microscopy, biochemistry, and lithography

NASA Astrophysics Data System (ADS)

Turcu, I. C. Edmond; Ross, Ian N.; Trenda, P.; Wharton, C. W.; Meldrum, R. A.; Daido, Hiroyuki; Schulz, M. S.; Fluck, P.; Michette, Alan G.; Juna, A. P.; Maldonado, Juan R.; Shields, Harry; Tallents, Gregory J.; Dwivedi, L.; Krishnan, J.; Stevens, D. L.; Jenner, T.; Batani, Dimitri; Goodson, H.

1994-02-01

At Rutherford Appleton Laboratory we developed a high repetition rate, picosecond, excimer laser system which generates a high temperature and density plasma source emitting approximately 200 mW (78 mW/sr) x ray average power at h(nu) approximately 1.2 KeV or 0.28 KeV < h(nu) < 0.53 KeV (the `water window'). At 3.37 nm wavelength the spectral brightness of the source is approximately 9 X 1011 photons/s/mm2/mrad2/0.1% bandwidth. The x-ray source serves a large user community for applications such as: scanning and holographic microscopy, the study of the biochemistry of DNA damage and repair, microlithography and spectroscopy.

The Tolman Surface Brightness Test for the Reality of the Expansion. III. Hubble Space Telescope Profile and Surface Brightness Data for Early-Type Galaxies in Three High-Redshift Clusters

NASA Astrophysics Data System (ADS)

Lubin, Lori M.; Sandage, Allan

2001-09-01

Photometric data for 34 early-type galaxies in the three high-redshift clusters Cl 1324+3011 (z=0.76), Cl 1604+4304 (z=0.90), and Cl 1604+4321 (z=0.92), observed with the Hubble Space Telescope (HST) and with the Keck 10 m telescopes by Oke, Postman, & Lubin, are analyzed to obtain the photometric parameters of mean surface brightness, magnitudes for the growth curves, and angular radii at various Petrosian η radii. The angular radii at η=1.3 mag for the program galaxies are all larger than 0.24". All the galaxies are well resolved at this angular size using HST, whose point-spread function is 0.05", half-width at half-maximum. The data for each of the program galaxies are listed at η=1.0, 1.3, 1.5, 1.7, and 2.0 mag. They are corrected by color equations and K-terms for the effects of redshift to the rest-frame Cape/Cousins I for Cl 1324+3011 and Cl 1604+4304 and R for Cl 1604+4321. The K-corrections are calculated from synthetic spectral energy distributions derived from evolving stellar population models of Bruzual & Charlot, that have been fitted to the observed broadband (BVRI) AB magnitudes of each program galaxy. The listed photometric data are independent of all cosmological parameters. They are the source data for the Tolman surface brightness test made in Paper IV.

Flux and Polarization Variability of OJ 287 during the Early 2016 Outburst

NASA Astrophysics Data System (ADS)

Rakshit, Suvendu; Stalin, C. S.; Muneer, S.; Neha, S.; Paliya, Vaidehi S.

2017-02-01

The gamma-ray blazar OJ 287 was in a high activity state during 2015 December-2016 February. Coinciding with this high brightness state, we observed this source for photometry on 40 nights in R-band and for polarimetry on nine epochs in UBV RI bands. During the period of our observations, the source brightness varied from 13.20 ± 0.04 mag to 14.98 ± 0.04 mag and the degree of polarization (P) fluctuated between 6.0% ± 0.3% and 28.3% ± 0.8% in R-band. Focusing on intranight optical variability (INOV), we find a duty cycle of about 71% using χ2-statistics, similar to that known for blazars. From INOV data, the shortest variability timescale is estimated to be 142 ± 38 minutes, yielding a lower limit of the observed Doppler factor δ0 = 1.17, the magnetic field strength B ≤ 3.8 G, and the size of the emitting region Rs < 2.28 × 1014 cm. On internight timescales, a significant anticorrelation between R-band flux and P is found. The observed P at U-band is generally larger than that observed at longer-wavelength bands, suggesting a wavelength-dependent polarization. Using V-band photometric and polarimetric data from Steward Observatory obtained during our monitoring period, we find a varied correlation between P and V-band brightness. While an anticorrelation is sometimes seen between P and V-band magnitude, no correlation is seen at other times, thereby suggesting the presence of more than one short-lived shock component in the jet of OJ 287.

OT2_eegami_6: SPIRE Snapshot Survey II: Using SPT/CODEX Massive Clusters as Powerful Gravitational Lenses

NASA Astrophysics Data System (ADS)

Egami, E.

2011-09-01

On the extragalactic side, one of the most remarkable results coming out of Herschel is the discovery of extremely bright (>100 mJy in the SPIRE bands) gravitationally lensed galaxies. The great sensitivity and mapping speed of SPIRE have enabled us to find these rare extraordinary objects. What is truly exciting about these bright lensed galaxies is that they enable a variety of detailed multi-wavelength follow-up observations, shedding new light on the physical properties of these high-redshift sources. In this regard, our OT1 program, "SPIRE Snapshot Survey of Massive Galaxy Clusters" turned out to be a great success. After imaging ~50 galaxies out of 279 in the program, we have already found two spectacularly bright lensed galaxies, one of which is at a redshift of 4.69. This type of cluster-lensed sources are not only bright but also spatially stretched over a large scale, so ALMA (or NOEMA in the north) is likely to be able to study them at the level of individual GMCs. Such studies will open up a new frontier in the study of high-redshift galaxies. Here, we propose to extend this highly efficient and effective survey of gravitationally lensed galaxies to another 353 clusters carefully chosen from the SPT and CODEX cluster samples. These samples contain newly discovered high-redshift (z>0.3) massive (>3-4e14 Msun) clusters, which can be used as powerful gravitational lenses to magnify sources at high redshift. With the OT1 and OT2 surveys together, we expect to find ~20 highly magnified SPIRE sources with exceptional brightnesses (assuming a discovery rate of ~1/30). Such a unique sample of extraordinary objects will enable a variety of follow-up sciences, and will therefore remain as a great legacy of the Herschel mission for years to come.

PKS 2123-463: A Confirmed Gamma-ray Blazar at High Redshift

NASA Technical Reports Server (NTRS)

DAmmando, F.; Rau, A.; Schady, P.; Finke, J.; Orienti, M.; Greiner, J.; Kann, D. A.; Ojha, R.; Foley, A. R.; Stevens, J.;

Intrinsic Brightness Temperatures of AGN Jets

NASA Astrophysics Data System (ADS)

Homan, D. C.; Kovalev, Y. Y.; Lister, M. L.; Ros, E.; Kellermann, K. I.; Cohen, M. H.; Vermeulen, R. C.; Zensus, J. A.; Kadler, M.

2006-05-01

We present a new method for studying the intrinsic brightness temperatures of the parsec-scale jet cores of active galactic nuclei (AGNs). Our method uses observed superluminal motions and observed brightness temperatures for a large sample of AGNs to constrain the characteristic intrinsic brightness temperature of the sample as a whole. To study changes in intrinsic brightness temperature, we assume that the Doppler factors of individual jets are constant in time, as justified by their relatively small changes in observed flux density. We find that in their median-low brightness temperature state, the sources in our sample have a narrow range of intrinsic brightness temperatures centered on a characteristic temperature, Tint~=3×1010 K, which is close to the value expected for equipartition, when the energy in the radiating particles equals the energy stored in the magnetic fields. However, in their maximum brightness state, we find that sources in our sample have a characteristic intrinsic brightness temperature greater than 2×1011 K, which is well in excess of the equipartition temperature. In this state, we estimate that the energy in radiating particles exceeds the energy in the magnetic field by a factor of ~105. We suggest that the excess of particle energy when sources are in their maximum brightness state is due to injection or acceleration of particles at the base of the jet. Our results suggest that the common method of estimating jet Doppler factors by using a single measurement of observed brightness temperature, the assumption of equipartition, or both may lead to large scatter or systematic errors in the derived values.

Galaxy And Mass Assembly: evolution of the Hα luminosity function and star formation rate density up to z < 0.35

NASA Astrophysics Data System (ADS)

Gunawardhana, M. L. P.; Hopkins, A. M.; Bland-Hawthorn, J.; Brough, S.; Sharp, R.; Loveday, J.; Taylor, E.; Jones, D. H.; Lara-López, M. A.; Bauer, A. E.; Colless, M.; Owers, M.; Baldry, I. K.; López-Sánchez, A. R.; Foster, C.; Bamford, S.; Brown, M. J. I.; Driver, S. P.; Drinkwater, M. J.; Liske, J.; Meyer, M.; Norberg, P.; Robotham, A. S. G.; Ching, J. H. Y.; Cluver, M. E.; Croom, S.; Kelvin, L.; Prescott, M.; Steele, O.; Thomas, D.; Wang, L.

2013-08-01

Measurements of the low-z Hα luminosity function, Φ, have a large dispersion in the local number density of sources (˜0.5-1 Mpc-3 dex-1), and correspondingly in the star formation rate density (SFRD). The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, different methods of correcting for dust obscuration and active galactic nucleus contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001 < SFRHα (M⊙ yr- 1) < 100 with which to robustly measure the evolution of the SFRD in the low-z Universe. The large number of high-SFR galaxies present in our sample allow an improved measurement of the bright end of the luminosity function, indicating that the decrease in Φ at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the far-infrared and radio. For GAMA and SDSS, we find the r-band apparent magnitude limit, combined with the subsequent requirement for Hα detection leads to an incompleteness due to missing bright Hα sources with faint r-band magnitudes.

Electron Source Brightness and Illumination Semi-Angle Distribution Measurement in a Transmission Electron Microscope.

PubMed

Börrnert, Felix; Renner, Julian; Kaiser, Ute

2018-05-21

The electron source brightness is an important parameter in an electron microscope. Reliable and easy brightness measurement routes are not easily found. A determination method for the illumination semi-angle distribution in transmission electron microscopy is even less well documented. Herein, we report a simple measurement route for both entities and demonstrate it on a state-of-the-art instrument. The reduced axial brightness of the FEI X-FEG with a monochromator was determined to be larger than 108 A/(m2 sr V).

Ocular hazards of light

NASA Technical Reports Server (NTRS)

Sliney, David H.

1994-01-01

The eye is protected against bright light by the natural aversion response to viewing bright light sources. The aversion response normally protects the eye against injury from viewing bright light sources such as the sun, arc lamps and welding arcs, since this aversion limits the duration of exposure to a fraction of a second (about 0.25 s). The principal retinal hazard resulting from viewing bright light sources is photoretinitis, e.g., solar retinitis with an accompanying scotoma which results from staring at the sun. Solar retinitis was once referred to as 'eclipse blindness' and associated 'retinal burn'. Only in recent years has it become clear that photoretinitis results from a photochemical injury mechanism following exposure of the retina to shorter wavelengths in the visible spectrum, i.e., violet and blue light. Prior to conclusive animal experiments at that time, it was thought to be a thermal injury mechanism. However, it has been shown conclusively that an intense exposure to short-wavelength light (hereafter referred to as 'blue light') can cause retinal injury. The product of the dose-rate and the exposure duration always must result in the same exposure dose (in joules-per-square centimeter at the retina) to produce a threshold injury. Blue-light retinal injury (photoretinitis) can result from viewing either an extremely bright light for a short time, or a less bright light for longer exposure periods. This characteristic of photochemical injury mechanisms is termed reciprocity and helps to distinguish these effects from thermal burns, where heat conduction requires a very intense exposure within seconds to cause a retinal coagulation otherwise, surrounding tissue conducts the heat away from the retinal image. Injury thresholds for acute injury in experimental animals for both corneal and retinal effects have been corroborated for the human eye from accident data. Occupational safety limits for exposure to UVR and bright light are based upon this knowledge. As with any photochemical injury mechanism must consider the action spectrum, which describes the relative effectiveness of different wavelengths in causing a photobiological effect. The action spectrum for photochemical retinal injury peaks at approximately 440 nm.

On the Nature of Bright Infrared Sources in the Small Magellanic Cloud: Interpreting MSX through the Lens of Spitzer

NASA Astrophysics Data System (ADS)

Kraemer, Kathleen E.; Sloan, G. C.

2015-01-01

We compare infrared observations of the Small Magellanic Cloud (SMC) by the Midcourse Space Experiment (MSX) and the Spitzer Space Telescope to better understand what components of a metal-poor galaxy dominate radiative processes in the infrared. The SMC, at a distance of ~60 kpc and with a metallicity of ~0.1-0.2 solar, can serve as a nearby proxy for metal-poor galaxies at high redshift. The MSX Point Source Catalog contains 243 objects in the SMC that were detected at 8.3 microns, the most sensitive MSX band. Multi-epoch, multi-band mapping with Spitzer, supplemented with observations from the Two-Micron All-Sky Survey (2MASS) and the Wide-field Infrared Survey Explorer (WISE), provides variability information, and, together with spectra from Spitzer for ~15% of the sample, enables us to determine what these luminous sources are. How many remain simple point sources? What fraction break up into multiple stars? Which are star forming regions, with both bright diffuse emission and point sources? How do evolved stars and stellar remnants contribute at these wavelengths? What role do young stellar objects and HII regions play? Answering these questions sets the stage for understanding what we will see with the James Webb Space Telescope (JWST).

Bright end of the luminosity function of high-mass X-ray binaries: contributions of hard, soft and supersoft sources

NASA Astrophysics Data System (ADS)

Sazonov, S.; Khabibullin, I.

2017-04-01

Using a spectral analysis of bright Chandra X-ray sources located in 27 nearby galaxies and maps of star-formation rate (SFR) and interstellar medium surface densities for these galaxies, we constructed the intrinsic X-ray luminosity function (XLF) of luminous high-mass X-ray binaries (HMXBs), taking into account absorption effects and the diversity of HMXB spectra. The XLF per unit SFR can be described by a power-law dN/dlog LX,unabs ≈ 2.0(LX,unabs/1039 erg s-1)-0.6 (M⊙ yr-1)-1 from LX,unabs = 1038 to 1040.5 erg s-1, where LX,unabs is the unabsorbed luminosity at 0.25-8 keV. The intrinsic number of luminous HMXBs per unit SFR is a factor of ˜2.3 larger than the observed number reported before. The intrinsic XLF is composed of hard, soft and supersoft sources (defined here as those with the 0.25-2 keV to 0.25-8 keV flux ratio of <0.6, 0.6-0.95 and >0.95, respectively) in ˜ 2:1:1 proportion. We also constructed the intrinsic HMXB XLF in the soft X-ray band (0.25-2 keV). Here, the numbers of hard, soft and supersoft sources prove to be nearly equal. The cumulative present-day 0.25-2 keV emissivity of HMXBs with luminosities between 1038 and 1040.5 erg s-1 is ˜5 × 1039 erg s-1(M⊙ yr-1)-1, which may be relevant for studying the X-ray preheating of the early Universe.

Time-resolved brightness measurements by streaking

NASA Astrophysics Data System (ADS)

Torrance, Joshua S.; Speirs, Rory W.; McCulloch, Andrew J.; Scholten, Robert E.

2018-03-01

Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

Swift XRT observation of HETE J1900.1-2455

NASA Astrophysics Data System (ADS)

Campana, S.

2005-06-01

Sergio Campana (INAF-OAB), Antonino Cucchiara (PSU) and Dave Burrows (PSU) on behalf of the XRT team report that Swift observed the seventh millisecond X-ray pulsar HETE J1900.1-2455 on 2005-06-24 UT21:03:37 for 1329 s in a single orbit. The source is bright an is observed in Window Timing (WT) mode, therefore not providing an image. The source count rate in the 0.5-10 keV energy band is 14.9+/-0.1 c/s.

VizieR Online Data Catalog: VLA-COSMOS 3 GHz Large Project (Smolcic+, 2017)

NASA Astrophysics Data System (ADS)

Smolcic, V.; Novak, M.; Bondi, M.; Ciliegi, P.; Mooley, K. P.; Schinnerer, E.; Zamorani, G.; Navarrete, F.; Bourke, S.; Karim, A.; Vardoulaki, E.; Leslie, S.; Delhaize, J.; Carilli, C. L.; Myers, S. T.; Baran, N.; Delvecchio, I.; Miettinen, O.; Banfield, J.; Balokovic, M.; Bertoldi, F.; Capak, P.; Frail, D. A.; Hallinan, G.; Hao, H.; Herrera Ruiz, N.; Horesh, A.; Ilbert, O.; Intema, H.; Jelic, V.; Klockner, H.-R.; Krpan, J.; Kulkarni, S. R.; McCracken, H.; Laigle, C.; Middleberg, E.; Murphy, E.; Sargent, M.; Scoville, N. Z.; Sheth, K.

2016-10-01

The catalog contains sources selected down to a 5σ(σ~2.3uJy/beam) threshold. This catalog can be used for statistical analyses, accompanied with the corrections given in the data & catalog release paper. All completeness & bias corrections and source counts presented in the paper were calculated using this sample. The total fraction of spurious sources in the COSMOS 2 sq.deg. is below 2.7% within this catalog. However, an increase of spurious sources up to 24% at 5.0=5.5 for single component sources (MULTI=0). The total fraction of spurious sources in the COSMOS 2 sq.deg. within such a selected sample is below 0.4%, and the fraction of spurious sources is below 3% even at the lowest S/N (=5.5). Catalog Notes: 1. Maximum ID is 10966 although there are 10830 sources. Some IDs were removed by joining them into multi-component sources. 2. Peak surface brightness of sources [uJy/beam] is not reported, but can be obtained by multiplying SNR with RMS. 3. High NPIX usually indicates extended or very bright sources. 4. Reported positional errors on resolved and extended sources should be considered lower limits. 5. Multicomponent sources have errors and S/N column values set to -99.0 Additional data information: Catalog date: 21-Mar-2016 Source extractor: BLOBCAT v1.2 (http://blobcat.sourceforge.net/) Observations: 384 hours, VLA, S-band (2-4GHz), A+C array, 192 pointings Imaging software: CASA v4.2.2 (https://casa.nrao.edu/) Imaging algorithm: Multiscale multifrequency synthesis on single pointings Mosaic size: 30000x30000 pixels (3.3 GB) Pixel size: 0.2x0.2 arcsec2 Median rms noise in the COSMOS 2 sq.deg.: 2.3uJy/beam Beam is circular with FWHM=0.75 arcsec Bandwidth-smearing peak correction: 0% (no corrections applied) Resolved criteria: Sint/Speak>1+6*snr^(-1.44) Total area covered: 2.6 sq.deg. (1 data file).