Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 1, 2023 | Published
Journal Article Open

X-Ray Polarization Observations of BL Lacertae

Middei, Riccardo ORCID icon
Liodakis, Ioannis ORCID icon
Perri, Matteo ORCID icon
Puccetti, Simonetta ORCID icon
Cavazzuti, Elisabetta ORCID icon
Di Gesu, Laura ORCID icon
Ehlert, Steven R. ORCID icon
Madejski, Grzegorz
Marscher, Alan P. ORCID icon
Marshall, Herman L. ORCID icon
Muleri, Fabio ORCID icon
Negro, Michela ORCID icon
Jorstad, Svetlana G. ORCID icon
Agís-González, Beatriz ORCID icon
Agudo, Ivan ORCID icon
Bonnoli, Giacomo ORCID icon
Bernardos, Maria I.
Casanova, Víctor
García-Comas, Maya ORCID icon
Husillos, César ORCID icon
Marchini, Alessandro ORCID icon
Sota, Alfredo ORCID icon
Kouch, Pouya M. ORCID icon
Lindfors, Elina ORCID icon
Borman, George A. ORCID icon
Kopatskaya, Evgenia N. ORCID icon
Larionova, Elena G. ORCID icon
Morozova, Daria A. ORCID icon
Savchenko, Sergey S. ORCID icon
Vasilyev, Andrey A. ORCID icon
Zhovtan, Alexey V.
Casadio, Carolina ORCID icon
Escudero, Juan ORCID icon
Myserlis, Ioannis ORCID icon
Hales, Antonio
Kameno, Seiji ORCID icon
Kneissl, Ruediger ORCID icon
Messias, Hugo ORCID icon
Nagai, Hiroshi ORCID icon
Blinov, Dmitry ORCID icon
Bourbah, Ioakeim G. ORCID icon
Kiehlmann, Sebastian ORCID icon
Kontopodis, Evangelos
Mandarakas, Nikos ORCID icon
Romanopoulos, Stylianos ORCID icon
Skalidis, Raphael ORCID icon
Vervelaki, Anna
Masiero, Joseph R. ORCID icon
Mawet, Dimitri ORCID icon
Millar-Blanchaer, Maxwell A. ORCID icon
Panopoulou, Georgia V. ORCID icon
Tinyanont, Samaporn ORCID icon
Berdyugin, Andrei V. ORCID icon
Kagitani, Masato ORCID icon
Kravtsov, Vadim ORCID icon
Sakanoi, Takeshi ORCID icon
Imazawa, Ryo ORCID icon
Sasada, Mahito ORCID icon
Fukazawa, Yasushi ORCID icon
Kawabata, Koji S. ORCID icon
Uemura, Makoto ORCID icon
Mizuno, Tsunefumi ORCID icon
Nakaoka, Tatsuya
Akitaya, Hiroshi ORCID icon
Gurwell, Mark ORCID icon
Rao, Ramprasad ORCID icon
Di Lalla, Niccoló ORCID icon
Cibrario, Nicoló ORCID icon
Donnarumma, Immacolata ORCID icon
Kim, Dawoon E. ORCID icon
Omodei, Nicola ORCID icon
Pacciani, Luigi ORCID icon
Poutanen, Juri ORCID icon
Tavecchio, Fabrizio ORCID icon
Antonelli, Lucio A. ORCID icon
Bachetti, Matteo ORCID icon
Baldini, Luca ORCID icon
Baumgartner, Wayne H. ORCID icon
Bellazzini, Ronaldo ORCID icon
Bianchi, Stefano ORCID icon
Bongiorno, Stephen D. ORCID icon
Bonino, Raffaella ORCID icon
Brez, Alessandro ORCID icon
Bucciantini, Niccoló ORCID icon
Capitanio, Fiamma ORCID icon
Castellano, Simone ORCID icon
Ciprini, Stefano ORCID icon
Costa, Enrico ORCID icon
De Rosa, Alessandra ORCID icon
Del Monte, Ettore ORCID icon
Di Marco, Alessandro ORCID icon
Doroshenko, Victor ORCID icon
Dovciak, Michal ORCID icon
Enoto, Teruaki ORCID icon
Evangelista, Yuri ORCID icon
Fabiani, Sergio ORCID icon
Ferrazzoli, Riccardo ORCID icon
García, Javier A. ORCID icon
Gunji, Shuichi ORCID icon
Hayashida, Kiyoshi
Heyl, Jeremy ORCID icon
Iwakiri, Wataru B. ORCID icon
Karas, Vladimir ORCID icon
Kitaguchi, Takao
Kolodziejczak, J. ORCID icon
Krawczynski, Henric ORCID icon
La Monaca, Fabio ORCID icon
Latronico, Luca ORCID icon
Maldera, Simone ORCID icon
Manfreda, Alberto ORCID icon
Marin, Frédéric ORCID icon
Marinucci, Andrea ORCID icon
Massaro, Francesco ORCID icon
Matt, Giorgio ORCID icon
Mitsuishi, Ikuyuki
Ng, C.-Y. ORCID icon
O'Dell, Stephen L. ORCID icon
Oppedisano, Chiara ORCID icon
Papitto, Alessandro ORCID icon
Pavlov, George G. ORCID icon
Peirson, Abel L. ORCID icon
Pesce-Rollins, Melissa ORCID icon
Petrucci, Pierre-Olivier ORCID icon
Pilia, Maura ORCID icon
Possenti, Andrea ORCID icon
Ramsey, Brian D.
Rankin, John ORCID icon
Ratheesh, Ajay ORCID icon
Romani, Roger W. ORCID icon
Sgró, Carmelo ORCID icon
Slane, Patrick ORCID icon
Soffitta, Paolo ORCID icon
Spandre, Gloria ORCID icon
Tamagawa, Toru ORCID icon
Taverna, Roberto ORCID icon
Tawara, Yuzuru
Tennant, Allyn F. ORCID icon
Thomas, Nicholas E. ORCID icon
Tombesi, Francesco ORCID icon
Trois, Alessio ORCID icon
Tsygankov, Sergey S. ORCID icon
Turolla, Roberto ORCID icon
Vink, Jacco ORCID icon
Weisskopf, Martin C. ORCID icon
Wu, Kinwah ORCID icon
Xie, Fei ORCID icon
Zane, Silvia ORCID icon


Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus that the synchrotron emission is responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae (BL Lac) performed with the Imaging X-ray Polarimetry Explorer, from which an upper limit to the polarization degree Π_X < 12.6% was found in the 2–8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton-synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac.

Additional Information

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. We thank the anonymous referee for their bright comments. The Imaging X-ray Polarimetry Explorer (IXPE) is a joint US and Italian mission. The US contribution is supported by the National Aeronautics and Space Administration (NASA) and led and managed by its Marshall Space Flight Center (MSFC), with industry partner Ball Aerospace (contract NNM15AA18C). The Italian contribution is supported by the Italian Space Agency (Agenzia Spaziale Italiana, ASI) through contract ASI-OHBI-2017-12-I.0, agreements ASI-INAF-2017-12-H0 and ASI-INFN-2017.13-H0, and its Space Science Data Center (SSDC), and by the Istituto Nazionale di Astrofisica (INAF) and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. This research used data products provided by the IXPE Team (MSFC, SSDC, INAF, and INFN) and distributed with additional software tools by the High-Energy Astrophysics Science Archive Research Center (HEASARC), at NASA Goddard Space Flight Center (GSFC). We acknowledge financial support from ASI-INAF agreement n. 2022-14-HH.0. The research at Boston University was supported in part by National Science Foundation grant AST-2108622 and NASA Swift Guest Investigator grant 80NSSC22K0537. This research has made use of data from the RoboPol program, a collaboration between Caltech, the University of Crete, IA-FORTH, IUCAA, the MPIfR, and the Nicolaus Copernicus University, which was conducted at Skinakas Observatory in Crete, Greece. The IAA-CSIC coauthors acknowledge financial support from the Spanish "Ministerio de Ciencia e Innovacion" (MCINN) through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). Acquisition and reduction of the POLAMI, TOP-MAPCAR, and OSN data was supported in part by MICINN through grants AYA2016-80889-P and PID2019-107847RB-C44. The POLAMI observations were carried out at the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). This Letter makes use of the following ALMA director's discretionary time data under proposal ESO#2021.A.00016.T. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), MOST, and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. Some of the data reported here are based on observations obtained at the Hale Telescope, Palomar Observatory as part of a continuing collaboration between the California Institute of Technology, NASA/JPL, Yale University, and the National Astronomical Observatories of China. This research made use of Photutils, an Astropy package for detection and photometry of astronomical sources (Bradley et al. 2019). G.V.P. acknowledges support by NASA through the NASA Hubble Fellowship grant #HST-HF2-51444.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. The data in this study include observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku, and the University of Oslo, representing Denmark, Finland, and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofísica de Andalucía (IAA) under a joint agreement with the University of Copenhagen and NOT. E.L. was supported by Academy of Finland projects 317636 and 320045. Part of the French contribution is supported by the Scientific Research National Center (CNRS) and the French Spatial Agency (CNES). Some of the data are based on observations collected at the Observatorio de Sierra Nevada, owned and operated by the Instituto de Astrofísica de Andalucía (IAA-CSIC). Further data are based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA), operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). D.B., S.K., R.S., and N. M. acknowledge support from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program under grant agreement No. 771282. C.C. acknowledges support by the European Research Council (ERC) under the HORIZON ERC Grants 2021 program under grant agreement No. 101040021. The Dipol-2 polarimeter was built in cooperation by the University of Turku, Finland, and the Leibniz Institut für Sonnenphysik, Germany, with support from the Leibniz Association grant SAW-2011-KIS-7. We are grateful to the Institute for Astronomy, University of Hawaii, for the allocated observing time. A.H. acknowledges The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work was supported by JST, the establishment of university fellowships toward the creation of science technology innovation; grant No. JPMJFS2129. This work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI grant Nos. JP21H01137. This work was also partially supported by Optical and Near-Infrared Astronomy Inter-University Cooperation Program from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. We are grateful to the observation and operating members of Kanata Telescope. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. Maunakea, the location of the SMA, is a culturally important site for the indigenous Hawaiian people; we are privileged to study the cosmos from its summit. Facilities: ALMA - Atacama Large Millimeter Array, CAO:2.2m - Calar Alto Observatory's 2.2 meter Telescope, CrAO:0.7m - , Hale - Palomar Observatory's 5.1m Hale Telescope, IRAM:30m - Institute de Radioastronomie Millimetrique 30 meter telescope, IXPE - , Kanata - , LX-200 - , NOT - Nordic Optical Telescope, NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, OSN:0.9m - IAA-CSIC Observatorio de Sierra Nevada's 0.9m Telescope, OSN:1.5m - IAA-CSIC Observatorio de Sierra Nevada's 1.5m Telescope, Perkins - Lowell Observatory's 72in Perkins Telescope, Skinakas:1.3m - Skinakas Observatory 1.3 meter Telescope, SMA - SubMillimeter Array, Swift - Swift Gamma-Ray Burst Mission, TU:0.6m - , XMM-Newton. -

Attached Files

Published - Middei_2023_ApJL_942_L10.pdf


Files (1.2 MB)
Name Size Download all
1.2 MB Preview Download

Additional details

August 22, 2023
October 25, 2023