Relevant bibliographies by topics / Flaring extragalactic sources

Academic literature on the topic 'Flaring extragalactic sources'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Flaring extragalactic sources"

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Lenain, Jean-Philippe. "Monitoring the Extragalactic High Energy Sky." Galaxies 7, no. 1 (January 3, 2019): 9. http://dx.doi.org/10.3390/galaxies7010009.

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Blazars are jetted active galactic nuclei with a jet pointing close to the line of sight, hence enhancing their intrinsic luminosity and variability. Monitoring these sources is essential in order to catch them flaring and promptly organize follow-up multi-wavelength observations, which are key to providing rich data sets used to derive e.g., the emission mechanisms at work, and the size and location of the flaring zone. In this context, the Fermi-LAT has proven to be an invaluable instrument, whose data are used to trigger many follow-up observations at high and very high energies. A few examples are illustrated here, as well as a description of different data products and pipelines, with a focus given on FLaapLUC, a tool in use within the H.E.S.S. collaboration.
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Lazio, T. Joseph W., and James M. Cordes. "Interstellar Scattering in the Galactic Anticenter." International Astronomical Union Colloquium 164 (1998): 329–30. http://dx.doi.org/10.1017/s0252921100045772.

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AbstractInterstellar scattering dictates the limiting resolution for many pulsars and OH masers and some extragalactic sources, a limit made more important by the advent of spacebased VLBI. Scattering observations have been biased toward the inner Galaxy, leaving largely unconstrained basic parameters such as the scattering medium’s extent in the outer Galaxy. Ionized gas at ~ 50 kpc is suggested by the appearance of H ɪ in nearby galaxies and models of low-redshift quasar absorption systems. We combine multiwavelength, VLBA observations of twelve extragalactic sources with previous scattering measurements of extragalactic sources and pulsars in the anticenter and constrain the radial extent of the scattering medium to 20 kpc, comparable to that of massive star formation. The H ɪɪ disk does not display significant flaring or warping, though this conclusion may reflect the coarse sampling.
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Sacahui, J. R., A. V. Penacchioni, A. Marinelli, A. Sharma, M. Castro, J. M. Osorio, and M. A. Morales. "STUDY OF BLAZAR ACTIVITY IN 10 YEAR FERMI-LAT DATA AND IMPLICATIONS FOR TEV NEUTRINO EXPECTATIONS." Revista Mexicana de Astronomía y Astrofísica 57, no. 2 (October 1, 2021): 251–68. http://dx.doi.org/10.22201/ia.01851101p.2021.57.02.01.

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Blazars are the most active extragalactic gamma-ray sources. They show sporadic bursts of activity, lasting from hours to months. In this work we present a 10-year analysis of a sample of bright sources detected by Fermi-LAT (100 MeV - 300 GeV). Using 2-week binned light curves (LC) we estimate the duty cycle (DC): fraction of time that the source spends in an active state. The objects show different DC values, with an average of 22.74% and 23.08% when considering (or not) the extragalactic background light ( EBL). Additionally, we study the so-called “blazar sequence” trend for the sample of selected blazars in the ten years of data. This analysis constrains a possible counterpart of sub-PeV neutrino emission during the quiescent states, leaving open the possibility to explain the observed IceCube signal during the flaring states.
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Stevens, J. A., D. C. Hannikainen, K. Wu, R. W. Hunstead, and D. J. McKay. "The radio flaring behaviour of GRO J1655--40: an analogy with extragalactic radio sources?" Monthly Notices of the Royal Astronomical Society 342, no. 2 (June 21, 2003): 623–28. http://dx.doi.org/10.1046/j.1365-8711.2003.06578.x.

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Britzen, S., A. Witzel, T. P. Krichbaum, J. Roland, and S. J. Wagner. "Monthly VLBI Monitoring of Selected Gamma-Bright Quasars." International Astronomical Union Colloquium 164 (1998): 43–44. http://dx.doi.org/10.1017/s0252921100044444.

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AbstractIn the past few years EGRET observations of extragalactic radio sources demonstrated the presence of blazars at high energies and supplied informations about their enormous luminosities. Questions arose whether outbursts at these high frequencies can be linked to structural changes in the radio regime and the need for VLBI monitoring became obvious. In the past two decades geodetic VLBI measurements gathered this kind of data.We analyzed λ =3.6 cm observations with high time-resolution (up to once a month) from the geodetic IRIS campaigns for the γ-ray active quasars PKS 0420-014 and PKS 0528+134. In both sources superluminally moving jet components could be traced over time periods of several years on curved trajectories. Both sources exhibit component ejections preceding the time of an observed gamma-ray flaring.
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Saxton, Richard D. "The Role of Wide Field X-ray Surveys in Astronomy." Proceedings of the International Astronomical Union 10, H16 (August 2012): 669–70. http://dx.doi.org/10.1017/s1743921314012824.

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AbstractWe review the history of X-ray sky surveys from the early experiments to the catalogues of 105 sources produced by ROSAT, Chandra and XMM-Newton. At bright fluxes the X-ray sky is shared between stars, accreting binaries and extragalactic sources while deeper surveys are dominated by AGN and clusters of galaxies. The X-ray background, found by the earliest missions, has been largely resolved into discrete sources at soft (0.3-2 keV) energies but at higher energies an important fraction still escapes detection. The possible identification of the missing flux with Compton-thick AGN has been probed in recent years by Swift and Integral.Variability seen in objects observed at different epochs has proved to be an excellent discriminator for rare classes of objects. The comparison of ROSAT All Sky Survey (RASS) and ROSAT pointed observations identified several Novae and high variability AGN as well as initiating the observational study of Tidal Disruption events. More recently the XMM-Newton slew survey, in conjunction with archival RASS data, has detected further examples of flaring objects which have been followed-up in near-real time at other wavelengths.
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van der Walt, D. J. "On the separation of the flaring component's emission in variable compact extragalactic radio sources - Results from a simple shocked relativistic jet model." Astrophysical Journal 409 (May 1993): 126. http://dx.doi.org/10.1086/172646.

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Raiteri, Claudia M., Maria I. Carnerero, Barbara Balmaverde, Eric C. Bellm, William Clarkson, Filippo D’Ammando, Maurizio Paolillo, et al. "Blazar Variability with the Vera C. Rubin Legacy Survey of Space and Time." Astrophysical Journal Supplement Series 258, no. 1 (December 22, 2021): 3. http://dx.doi.org/10.3847/1538-4365/ac3bb0.

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Abstract With their emission mainly coming from a relativistic jet pointing toward us, blazars are fundamental sources for studying extragalactic jets and their central engines, consisting of supermassive black holes fed by accretion disks. They are also candidate sources of high-energy neutrinos and cosmic rays. Because of the jet orientation, the nonthermal blazar emission is Doppler beamed; its variability is unpredictable, and it occurs on timescales from less than 1 hr to years. Comprehension of the diverse mechanisms producing the flux and spectral changes requires well-sampled multiband light curves over long time periods. In particular, outbursts are the best test bench for shedding light on the underlying physics, especially when studied in a multiwavelength context. The Vera C. Rubin Legacy Survey of Space and Time (Rubin-LSST) will monitor the southern sky for 10 yr in six photometric bands, offering a formidable tool for studying blazar variability features in a statistical way. The alert system will allow us to trigger follow-up observations of outstanding events, especially at high (keV-to-GeV) and very high (TeV) energies. We here examine the simulated Rubin-LSST survey strategies with the aim of understanding which cadences are more suitable for blazar variability science. Our metrics include light curve and color sampling. We also investigate the problem of saturation, which will affect the brightest and many flaring sources, and will have a detrimental impact on follow-up observations.
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Agrawal, V. K., and Anuj Nandi. "AstroSat view of LMC X-2: evolution of broad-band X-ray spectral properties along a complete Z-track." Monthly Notices of the Royal Astronomical Society 497, no. 3 (August 6, 2020): 3726–33. http://dx.doi.org/10.1093/mnras/staa2063.

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ABSTRACT In this paper, we report the first results of the extragalactic Z-source Large Magellanic Cloud (LMC) X-2 obtained using the ∼140 ks observations with Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) onboard AstroSat. The Hardness-Intensity Diagram created with the LAXPC data revealed a complete Z-pattern of the source, showing all the three branches. We studied the evolution of the broad-band X-ray spectra in the energy range of 0.5–20.0 keV along the Z-track, a first such study of this source. The X-ray spectra of the different parts of the Z-pattern were well described by an absorbed Comptonized component. An absence of the accretion disc component suggests that the disc is most probably obscured by a Comptonized region. The best fit electron temperature (kTe) was found to be in the range of 1.7–2.1 keV and optical depth (τ) was found to be in the range of 13.2–17.5. The optical depth (τ) increased as the source moved from the normal/flaring branch (NB/FB) vertex to the upper part of the FB, suggesting a possible outflow triggered by a strong radiation pressure. The power density spectra (PDS) of HB and NB could be fitted with a pure power law of index α∼1.68 and 0.83, respectively. We also found a weak evidence of quasi-periodic oscillation (2.8σ) in the FB. The intrinsic luminosity of the source varied between (1.03–1.79) × 1038 erg s−1. We discuss our results by comparing with other Z-sources and the previous observations of LMC X-2.
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Book chapters on the topic "Flaring extragalactic sources"

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Steffen, W., A. J. Holloway, A. Pedlar, and D. J. Axon. "IRAS 0421+0400: A Curious Spiral with Flaring Jets." In Extragalactic Radio Sources, 179–80. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0295-4_67.

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