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Title: New ALMA and Fermi /LAT Observations of the Large-scale Jet of PKS 0637−752 Strengthen the Case Against the IC/CMB Model

Abstract

The Chandra X-ray observatory has discovered several dozen anomalously X-ray-bright jets associated with powerful quasars. A popular explanation for the X-ray flux from the knots in these jets is that relativistic synchrotron-emitting electrons inverse-Compton scatter cosmic microwave background (CMB) photons to X-ray energies (the IC/CMB model). This model predicts a high gamma-ray flux that should be detectable by the Fermi /Large Area Telescope (LAT) for many sources. GeV-band upper limits from Fermi /LAT for the well-known anomalous X-ray jet in PKS 0637−752 were previously shown in Meyer et al. to violate the predictions of the IC/CMB model. Previously, measurements of the jet synchrotron spectrum, important for accurately predicting the gamma-ray flux level, were lacking between radio and infrared wavelengths. Here, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the large-scale jet at 100, 233, and 319 GHz, which further constrain the synchrotron spectrum, supporting the previously published empirical model. We also present updated limits from the Fermi /LAT using the new “Pass 8” calibration and approximately 30% more time on source. With these deeper limits, we rule out the IC/CMB model at the 8.7 σ level. Finally, we demonstrate that complete knowledge of the synchrotron SED is criticalmore » in evaluating the IC/CMB model.« less

Authors:
; ;  [1]; ;  [2]; ;  [3];  [4]
  1. University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)
  2. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
  3. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching-bei-München (Germany)
  4. ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands)
Publication Date:
OSTI Identifier:
22654558
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; CALIBRATION; FORECASTING; GALAXIES; GAMMA RADIATION; GEV RANGE; GHZ RANGE; QUASARS; RELATIVISTIC RANGE; RELICT RADIATION; SPECTRA; TELESCOPES; WAVELENGTHS; X RADIATION

Citation Formats

Meyer, Eileen T., Breiding, Peter, Georganopoulos, Markos, Oteo, Iván, Ivison, R. J., Zwaan, Martin A., Laing, Robert, and Godfrey, Leith, E-mail: meyer@umbc.edu. New ALMA and Fermi /LAT Observations of the Large-scale Jet of PKS 0637−752 Strengthen the Case Against the IC/CMB Model. United States: N. p., 2017. Web. doi:10.3847/2041-8213/835/2/L35.
Meyer, Eileen T., Breiding, Peter, Georganopoulos, Markos, Oteo, Iván, Ivison, R. J., Zwaan, Martin A., Laing, Robert, & Godfrey, Leith, E-mail: meyer@umbc.edu. New ALMA and Fermi /LAT Observations of the Large-scale Jet of PKS 0637−752 Strengthen the Case Against the IC/CMB Model. United States. doi:10.3847/2041-8213/835/2/L35.
Meyer, Eileen T., Breiding, Peter, Georganopoulos, Markos, Oteo, Iván, Ivison, R. J., Zwaan, Martin A., Laing, Robert, and Godfrey, Leith, E-mail: meyer@umbc.edu. Wed . "New ALMA and Fermi /LAT Observations of the Large-scale Jet of PKS 0637−752 Strengthen the Case Against the IC/CMB Model". United States. doi:10.3847/2041-8213/835/2/L35.
@article{osti_22654558,
title = {New ALMA and Fermi /LAT Observations of the Large-scale Jet of PKS 0637−752 Strengthen the Case Against the IC/CMB Model},
author = {Meyer, Eileen T. and Breiding, Peter and Georganopoulos, Markos and Oteo, Iván and Ivison, R. J. and Zwaan, Martin A. and Laing, Robert and Godfrey, Leith, E-mail: meyer@umbc.edu},
abstractNote = {The Chandra X-ray observatory has discovered several dozen anomalously X-ray-bright jets associated with powerful quasars. A popular explanation for the X-ray flux from the knots in these jets is that relativistic synchrotron-emitting electrons inverse-Compton scatter cosmic microwave background (CMB) photons to X-ray energies (the IC/CMB model). This model predicts a high gamma-ray flux that should be detectable by the Fermi /Large Area Telescope (LAT) for many sources. GeV-band upper limits from Fermi /LAT for the well-known anomalous X-ray jet in PKS 0637−752 were previously shown in Meyer et al. to violate the predictions of the IC/CMB model. Previously, measurements of the jet synchrotron spectrum, important for accurately predicting the gamma-ray flux level, were lacking between radio and infrared wavelengths. Here, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the large-scale jet at 100, 233, and 319 GHz, which further constrain the synchrotron spectrum, supporting the previously published empirical model. We also present updated limits from the Fermi /LAT using the new “Pass 8” calibration and approximately 30% more time on source. With these deeper limits, we rule out the IC/CMB model at the 8.7 σ level. Finally, we demonstrate that complete knowledge of the synchrotron SED is critical in evaluating the IC/CMB model.},
doi = {10.3847/2041-8213/835/2/L35},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}