Download or read book New Chandra Observations of the Jet in 3C273 1 Softer X ray Than Radio Spectra and the X ray Emission Mechanism written by and published by . This book was released on 2006 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The jet in 3C273 is a high-power quasar jet with radio, optical and X-ray emission whose size and brightness allow a detailed study of the emission processes acting in it. We present deep Chandra observations of this jet and analyze the spectral properties of the jet emission from radio through X-rays. We find that the X-ray spectra are significantly softer than the radio spectra in all regions of the bright part of the jet except for the first bright ''knot A'', ruling out a model in which the X-ray emission from the entire jet arises from beamed inverse-Compton scattering of cosmic microwave background photons in a single-zone jet flow. Within two-zone jet models, we find that a synchrotron origin for the jet's X-rays requires fewer additional assumptions than an inverse-Compton model, especially if velocity shear leads to efficient particle acceleration in jet flows.
Download or read book Chandra Reveals Twin X ray Jets in the Powerful FR II Radio Galaxy 3C353 written by and published by . This book was released on 2008 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report X-ray imaging of the powerful FR II radio galaxy 3C 353 using the Chandra X-ray Observatory. 3C 353's two 4-inch wide and 2-feet long jets allow us to study in detail the internal structure of the large-scale relativistic outflows at both radio and X-ray photon energies with the sub-arcsecond spatial resolution provided by the VLA and Chandra instruments. In a 90 ks Chandra observation, we have detected X-ray emission from most radio structures in 3C 353, including the nucleus, the jet and the counterjet, the terminal jet regions (hotspots), and one radio lobe. We show that the detection of the X-ray emission associated with the radio knots and counterknots, which is most likely non-thermal in origin, puts several crucial constraints on the X-ray emission mechanisms in powerful large-scale jets of quasars and FR II sources. In particular, we show that this detection is inconsistent with the inverse-Compton model proposed in the literature, and instead implies a synchrotron origin of the X-ray jet photons. We also find that the width of the X-ray counterjet is possibly narrower than that measured in radio bands, that the radio-to-X-ray flux ratio decreases systematically downstream along the jets, and that there are substantial (kpc-scale) offsets between the positions of the X-ray and radio intensity maxima within each knot, whose magnitudes increase away from the nucleus. We discuss all these findings in the wider context of the physics of extragalactic jets, proposing some particular though not definitive solutions or interpretations for each problem. In general, we find that the synchrotron X-ray emission of extragalactic large-scale jets is not only shaped by the global hydrodynamical configuration of the outflows, but is also likely to be very sensitive to the microscopic parameters of the jet plasma. A complete, self-consistent model for the X-ray emission of extragalactic jets still remains elusive.
Download or read book Hubble Science Year in Review written by and published by . This book was released on 2006 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High resolution Multi wavelength Study of the Jet in 3C273 written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The jet in 3C273 is one of only a few extragalactic optical synchrotron jets which are large and bright enough to be studied in detail. We present new broad-band observations of this jet at the unprecedented common resolution of 0.3' which have been obtained with the Very Large Array at radio and the Hubble Space Telescope at infrared, optical and ultraviolet wavelengths. These observations reveal a flattening of the high-frequency spectrum of the jet, a surprising feature which cannot be accounted for by any single-population synchrotron model. Both the observed flattening of the high-frequency spectrum and the X-ray emission from the jet can be explained by a model in which two distinct electron populations contribute to the jet's emission. We fit spatially resolved synchrotron spectra for the jet and determine the run of the maximum particle energy. The decrease of the maximum particle energy along the jet is much slower than expected from the observed synchrotron emission. We find no evidence for localised acceleration or loss sites. We show that relativistic beaming and/or sub-equipartition magnetic fields cannot remove the discrepancy between light-travel time along the jet and the shorter lifetime of electrons emitting optical synchrotron radiation. We consider this further evidence in favour of a distributed electron acceleration process.
Download or read book Precision X ray Spectroscopy of 3C 273 Jet Knots written by Mark J. Avara and published by . This book was released on 2008 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present results from precision X-ray spectroscopy using high-resolution ([delta lambda] = 0.01A) spectra of 3C 273 jet knots extracted from eight observations made using Chandra in conjunction with the HETGS. Using these spectra we searched for narrow emission line candidates and, based on significance values calculated for the observed photon counts in each bin of the spectrum of the entire jet, we selected three possible emission candidates and attempted to match these with known highly emissive X-ray emission lines. From this calculation we found the temperature of the X-ray emitting plasma to be 106.8 K, the bulk velocity of the knots to be 0.78 times the speed of light, and the electron density in the jet to be 0.043+/-.007 .009cm-3.
Download or read book Multi wavelength Observations and Theoretical Modeling of Powerful Quasar Jets written by Peter Breiding and published by . This book was released on 2018 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Chandra X-ray Observatory has discovered kpc-scale X-ray jets in many powerful quasars over the past 2 decades (Harris & Krawczynski, 2006). In many cases, these X-rays cannot be explained by the extension of the radio-optical spectrum produced by synchrotron-emitting electrons in the jet, since the observed X-ray flux is too high and/or the X-ray spectral index is too hard. A widely accepted model for the X-ray emission, first proposed by Celotti et al. (2001) and Tavecchio et al. (2000), posits that the X-rays are produced when relativistic electrons in the jet up-scatter ambient cosmic microwave background (CMB) photons via inverse-Compton scattering from microwave to X-ray energies (the IC/CMB model). However, modeling the X-ray emission in these jets with the IC/CMB model requires high levels of IC/CMB gamma-ray emission (Georganopoulos et al., 2006), which we have looked for using the Fermi/LAT gamma-ray space telescope. Another viable model for the large scale jet X-ray emission, favored by the results of Meyer et al. (2015) and Meyer & Georganopoulos (2014), is a second population of synchrotron-emitting electrons with up to multi-TeV energies. In contrast with the second synchrotron interpretation, the IC/CMB model requires jets with high kinetic powers (exceeding the Eddington luminosity in some cases), which remain highly relativistic (Î~10) up to kpc scales. In this thesis, I will present recently obtained deep gamma-ray upper-limits from the Fermi/LAT which rule out the IC/CMB model in a large sample of sources previously modeled with IC/CMB, and discuss the properties of the growing sample of non-IC/CMB anomalous X-ray jets and the implications for jet energetics and environmental impact. Additionally, I will present a model for the GeV emission observed in powerful gamma-ray flaring blazars, thought to originate several pc away from the central engine.
Download or read book The 300 Kpc Long X Ray Jet in PKS 1127 145 Z written by and published by . This book was released on 2006 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chandra X ray Observations of AWM 7 written by Justin Spring and published by . This book was released on 2003 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The X ray Background written by Xavier Barcons and published by Cambridge University Press. This book was released on 1992-07-31 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the current observational knowledge and understanding of the cosmic X-ray background.
Download or read book The High Energy Universe at Sharp Focus written by Eric Matthew Schlegel and published by . This book was released on 2002 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Chandra Hetgs X Ray Grating Spectrum of Eta Carinae written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-08 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emission. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively 'resolving' the shock. If so, the pre-shock wind velocities are approximately 700 and 1800 km/s in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from 71 Carinae and from the hidden companion star. The forbidden-to-intercombination line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 angstroms, first detected by ASCA, is clearly resolved from the thermal iron line in the CHANDRA grating spectrum. The Fe fluorescent line is weaker in our CHANDRA observation than in any of the ASCA spectra. The CHANDRA observation also provides the first high-time resolution lightcurve of the uncontaminated stellar X-ray emission from 77 Carinae and shows that there is no significant, coherent variability during the CHANDRA observation. The 77 Carinae CHANDRA grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding wind emission in a massive binary.
Download or read book Signals from Space written by Robert Naeye and published by Steck-Vaughn. This book was released on 2001 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Chandra X-ray Observatory is the largest object ever carried into space by the Space Shuttle. Scientists and engineers faced many challenges before they completed the powerful new satellite. But their hard work paid off. The National Aeronautics and Space Administration (NASA) launched Chandra in July 1999. Today, this remarkable satellite sends vivid and astounding X-ray images back to Earth.
Download or read book The Restless Universe written by Eric Matthew Schlegel and published by . This book was released on 2002 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carl Sagan once noted that there is only one generation that gets to see things for the first time. We are in the midst of such a time right now, standing on the threshold of discovery in the young and remarkable field of X-ray astronomy. In The Restless Universe, astronomer Eric Schlegel offers readers an informative survey of this cutting-edge science. Two major space observatories launched in the last few years--NASA's Chandra and the European Newton--are now orbiting the Earth, sending back a gold mine of data on the X-ray universe. Schlegel, who has worked on the Chandra project for seven years, describes the building and launching of this space-based X-ray observatory. But the book goes far beyond the story of Chandra. What Schlegel provides here is the background a nonscientist would need to grasp the present and follow the future of X-ray astronomy. He looks at the relatively brief history of the field, the hardware used to detect X-rays, the satellites--past, present, and future--that have been or will be flown to collect the data, the way astronomers interpret this data, and, perhaps most important, the insights we have already learned as well as speculations about what we may soon discover. And throughout the book, Schlegel conveys the excitement of looking at the universe from the perspective brought by these new observatories and the sharper view they deliver. Drawing on observations obtained from Chandra, Newton, and previous X-ray observatories, The Restless Universe gives a first look at an exciting field which significantly enriches our understanding of the universe.
Download or read book The X Ray Core of the Low Luminosity Radio Galaxy 3C346 and ASCA Spectroscopy to Test BL LAC Radio Galaxy Unification written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-09-27 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radio galaxies are relatively faint sources for Advanced Spacecraft for Cosmology Astrophysics (ASCA), and so in order to get the best possible results from the observations two things have been necessary, both of which delayed the fast preparation of papers. Firstly, the best possible data screening and background subtraction were necessary to improve the signal-to-noise, and all our several initial analysis trials were discarded in favor of using FTOOLS versions 4.1 and above. Secondly, we found that the ASCA spectra were statistically too poor to discriminate well between non-thermal and thermal models, never mind the mixture of the two which we expected on the basis of our ROSAT spatial separation of components in radio galaxies. This means that in each case we have needed to combine the ASCA spectroscopy with analysis of data from other X-ray or radio observations in order to exploit the ASCA data to the full. Our analysis for 3C 346 has yielded the cleanest final result. This powerful radio galaxy at a redshift of 0.161, lies in a poor cluster, which we have separated well from the dominant X-ray component of unresolved emission using a spatial analysis of archival ROSAT data. We were then able to fix the thermal component in our ASCA spectral analysis, and have found evidence that the unresolved emission varied by 32 +/- 13% over the 18 months between the ROSAT and ASCA observations. The unresolved X-ray emission does not suffer from intrinsic absorption, and we have related it to radio structures on both milliarcsecond scales and the arcsecond scales which Chandra can resolve. The source is a target of a Chandra AO2 proposal which we have recently submitted to follow up on our ASCA (and ROSAT) work. 3C 346's orientation to the line of sight is uncertain. However, the absence of X-ray absorption, and the radio/optical/X-ray colors, when combined with with previous radio evidence that the source is a foreshortened radio galaxy of the FRII class, suggest that t
Download or read book An Infrared Study of the Large Scale Jet in Quasar PKS 1136 135 written by and published by . This book was released on 2007 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present Spitzer IRAC imaging of the large-scale jet in the quasar PKS 1136-135 at wavelengths of 3.6 and 5.8 [mu]m, combined with previous VLA, HST, and Chandra observations. We clearly detect infrared emission from the jet, resulting in the most detailed multifrequency data among the jets in lobe-dominated quasars. The spectral energy distributions of the jet knots have significant variations along the jet, like the archetypal jet in 3C 273. The infrared measurements with IRAC are consistent with the previous idea that the jet has two spectral components, namely (1) the low-energy synchrotron spectrum extending from radio to infrared, and (2) the high-energy component responsible for the X-ray flux. The optical fluxes may be a mixture of the two components. We consider three radiation models for the high-energy component: inverse Compton scattering of cosmic microwave background (CMB) photons by radio-emitting electrons in a highly relativistic jet, synchrotron radiation by a second distinct electron population, and synchrotron radiation by ultra high energy protons. Each hypothesis leads to important insights into and constraints on particle acceleration in the jet, as well as the basic physical properties of the jet such as bulk velocity, transporting power, and particle contents.
Download or read book The Chandra X ray Observatory written by J. Belinda Wilkes and published by . This book was released on 2019-12-31 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: NASA's Chandra X-Ray Observatory has ushered in a revolution in X-ray astronomy. Over the last two decades Chandra has captured stunning celestial X-ray images, measured spectra and monitored light curves to reveal and map the hottest, most energetic regions of the universe. Celebrating its 20th anniversary, this book includes current reviews of the major discoveries and scientific results made by Chandra, authored by leading experts in each sub-field. Documenting the progress, discoveries and developments implemented by the mission, this book provides its readers with a comprehensive review of the mission thus far and its potential future implications. The book includes beautiful images of celestial sources generated from Chandra and multi-wavelength data. 3D figures, movies and interactive illustrations are also used throughout to enhance the text.
Download or read book Confronting X Ray Emission Models with TheHighest Redshift Kiloparsec Scale Jets written by C. C. Cheung and published by . This book was released on 2006 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: A newly identified kiloparsec-scale X-ray jet in the high-redshift z=3.89 quasar 1745+624 is studied with multi-frequency Very Large Array, Hubble Space Telescope, and Chandra X-ray imaging data. This is only the third large-scale X-ray jet beyond z> 3 known and is further distinguished as being the most luminous relativistic jet observed at any redshift, exceeding 10{sup 45} erg/s in both the radio and X-ray bands. Apart from the jet's extreme redshift, luminosity, and high inferred equipartition magnetic field (in comparison to local analogues), its basic properties such as X-ray/radio morphology and radio polarization are similar to lower-redshift examples. Its resolved linear structure and the convex broad-band spectral energy distributions of three distinct knots are also a common feature among known powerful X-ray jets at lower-redshift. Relativistically beamed inverse Compton and ''non-standard'' synchrotron models have been considered to account for such excess X-ray emission in other jets; both models are applicable to this high-redshift example but with differing requirements for the underlying jet physical properties, such as velocity, energetics, and electron acceleration processes. One potentially very important distinguishing characteristic between the two models is their strongly diverging predictions for the X-ray/radio emission with increasing redshift. This is considered, though with the limited sample of three z> 3 jets it is apparent that future studies targeted at very high-redshift jets are required for further elucidation of this issue. Finally, from the broad-band jet emission we estimate the jet kinetic power to be no less than 10{sup 46} erg/s, which is about 10% of the Eddington luminosity corresponding to this galaxy's central supermassive black hole mass M{sub BH} {approx}> 10{sup 9} M{sub {circle_dot}} estimated here via the virial relation. The optical luminosity of the quasar core is about ten times over Eddington, hence the inferred jet power seems to be much less than that available from mass accretion. The apparent super-Eddington accretion rate may however suggest contribution of the unresolved jet emission to the observed optical flux of the nucleus.
