Gamma-ray emission in radio galaxies under the VLBI scope II. The relationship between gamma-ray emission and parsec-scale jets in radio galaxies
| dc.contributor.author | Angioni, R. | |
| dc.contributor.author | Ros, E. | |
| dc.contributor.author | Kadler, M. | |
| dc.contributor.author | Ojha, R. | |
| dc.contributor.author | Mueller, C. | |
| dc.contributor.author | Edwards, P.G. | |
| dc.contributor.author | Burd, P.R. | |
| dc.contributor.author | Carpenter, B. | |
| dc.contributor.author | Dutka, M. S. | |
| dc.contributor.author | Gulyaev, S. | |
| dc.contributor.author | Hase, H. | |
| dc.contributor.author | Horiuchi, S. | |
| dc.contributor.author | Krauss, F. | |
| dc.contributor.author | Lovell, J.E.J. | |
| dc.contributor.author | Natusch, T. | |
| dc.contributor.author | Phillips, C. | |
| dc.contributor.author | Ploetz, C. | |
| dc.contributor.author | Quick, J. F. H. | |
| dc.contributor.author | Roesch, F. | |
| dc.contributor.author | Schulz, R. | |
| dc.contributor.author | Stevens, J. | |
| dc.contributor.author | Tzioumis, A. K. | |
| dc.contributor.author | Weston, S. | |
| dc.contributor.author | Wilms, J. | |
| dc.contributor.author | Zensus, J. A. | |
| dc.date.accessioned | 2020-09-15T16:20:07Z | |
| dc.date.available | 2020-09-15T16:20:07Z | |
| dc.date.issued | 2020-07-20 | |
| dc.description.abstract | Aims. This is the second paper in our series studying the evolution of parsec-scale radio emission in radio galaxies in the Southern Hemisphere. Following our study of the radio and high-energy properties of γ-ray-emitting sources, here we investigate the kinematic and spectral properties of the parsec-scale jets of radio galaxies that have not yet been detected by the Fermi Large Area Telescope (Fermi-LAT) instrument on board NASA’s Fermi Gamma-ray Space Telescope. For many sources, these results represent the first milliarcsecond resolution information in the literature. These studies were conducted within the framework of the Tracking Active Nuclei with Austral Milliarcsecond Interferometry (TANAMI) monitoring program and in the context of high-energy γ-ray observations from Fermi-LAT. Methods. We took advantage of the regular 8.4 GHz and 22.3 GHz Very Long Baseline Interferometry (VLBI) observations provided by the TANAMI monitoring program, and explored the kinematic properties of six γ-ray-faint radio galaxies. We complemented this with ∼ 8.5 years of Fermi-LAT data, deriving updated upper limits on the γ-ray emission from this subsample of TANAMI radio galaxies. We included publicly available VLBI kinematics of γ-ray-quiet radio galaxies monitored by the MOJAVE program and performed a consistent Fermi-LAT analysis. We combined these results with those from our previous paper to construct the largest sample of radio galaxies with combined VLBI and γ-ray measurements to date. The connection between parsec-scale jet emission and high-energy properties in the misaligned jets of radio galaxies was explored. Results. For the first time, we report evidence of superluminal motion up to βapp = 3.6 in the jet of the γ-ray-faint radio galaxy PKS 2153−69. We find a clear trend of higher apparent speed as a function of distance from the jet core, which indicates that the jet is still being accelerated on scales of tens of parsecs, or ∼ 105 Rs, corresponding to the end of the collimation and cceleration zone in nearby radio galaxies. We find evidence of subluminal apparent motion in the jets of PKS 1258−321 and IC 4296, and no measurable apparent motion for PKS 1549−79, PKS 1733−565, and PKS 2027−308. For all these sources, TANAMI provides the first multi-epoch kinematic analysis on parsec scales. We then compare the VLBI properties of γ-ray-detected and undetected radio galaxies, and find that the two populations show a significantly different distribution of median core flux density, and, possibly, of median core brightness temperature. In terms of correlation between VLBI and γ-ray properties, we find a significant correlation between median core flux density and γ-ray flux, but no correlation with typical Doppler boosting indicators such as median core brightness temperature and core dominance. Conclusions. Our study suggests that high-energy emission from radio galaxies is related to parsec-scale radio emission from the inner jet, but is not driven by Doppler boosting effects, in contrast to the situation in their blazar counterparts. This implies that γ-ray loudness does not necessarily reflect a higher prevalence of boosting effects | en_US |
| dc.description.sponsorship | We thank Laura Vega García for the development of the Python GUI-based code that was used for the kinematic analysis and the spectral index maps. We thank Frank Schinzel as the Fermi-LAT collaboration internal referee. We also thank the journal referee for a constructive report. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration;data from the MOJAVE database that is maintained by the MOJAVE team (Lister et al. 2018); APLpy, an open-source plotting package for Python (Robitaille & Bressert 2012); Astropy,4 a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018) C.M. acknowledges support from the ERC Synergy Grant BlackHoleCam: Imaging the Event Horizon of Black Holes (Grant 610058). R.S. gratefully acknowledges support from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Advanced Grant RADIOLIFE-320745. F.K. was supported as an Eberly Research Fellow by the Eberly College of Science at the Pennsylvania State University. The Fermi-LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT, as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States; the Commissariat á lEnergie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France; the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy; the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan; and the K. A. Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Etudes Spatiales in France. This work was performed in part under DOE Contract DE-AC02-76SF00515. The Long Baseline Array is part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. This study made use of data collected through the AuScope initiative. AuScope Ltd is funded under the National Collaborative Research Infrastructure Strategy (NCRIS), an Australian Commonwealth Government Programme. This work made use of the Swinburne University of Technology software correlator, developed as part of the Australian Major National Research Facilities Programme. This work was supported by resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia. Hartebeesthoek Radio Astronomy Observatory(HartRAO) is a facility of the National Research Foundation (NRF) of South Africa. This research was funded in part by NASA through Fermi Guest Investigator grants NNH10ZDA001N, NNH12ZDA001N, and NNH13ZDA001NFERMI (proposal numbers 41213, 61089, and 71326, respectively). This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association through a contract with NASA. | en_US |
| dc.description.uri | https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202038236 | en_US |
| dc.format.extent | 39 pages | en_US |
| dc.genre | journal articles postprints | en_US |
| dc.identifier | doi:10.13016/m2crna-pylg | |
| dc.identifier.citation | R. Angioni et al., Gamma-ray emission in radio galaxies under the VLBI scope II. The relationship between gamma-ray emission and parsec-scale jets in radio galaxies, A&A (2020), doi: https://doi.org/10.1051/0004-6361/202038236 | en_US |
| dc.identifier.uri | https://doi.org/10.1051/0004-6361/202038236 | |
| dc.identifier.uri | http://hdl.handle.net/11603/19653 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | EDP sciences | en_US |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Center for Space Sciences and Technology | |
| dc.relation.ispartof | UMBC Physics Department | |
| dc.relation.ispartof | UMBC Faculty Collection | |
| dc.rights | This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author. | |
| dc.rights | © ESO 2020. | |
| dc.title | Gamma-ray emission in radio galaxies under the VLBI scope II. The relationship between gamma-ray emission and parsec-scale jets in radio galaxies | en_US |
| dc.type | Text | en_US |