Constraints on the X-Ray and Very-high-energy Gamma-Ray Flux from Supernova Remnant W44

Abstract Observations of GeV gamma-ray emission from the well-studied mixed-morphology supernova remnant (SNR) W44 by Fermi-Large Area Telescope and AGILE imply that it is a site of significant cosmic-ray acceleration. The spectral energy distribution (SED) derived from the GeV data suggests that the gamma-ray emission likely originates from the decay of neutral pions generated by cosmic-ray interactions. It is essential to measure the SED of W44 in the X-ray and very-high-energy (VHE) gamma-ray bands to verify the hadronic origin of the emission and to gauge the potential contributions from leptonic emission. We report an upper limit of the nonthermal X-ray flux from W44 of 5 × 10 −13 erg cm −2 s −1 in the 0.5–8.0 keV band based on ∼300 ks of XMM-Newton observations. The X-ray upper limit is consistent with previously estimated hadronic models, but in tension with the leptonic models. We estimate the VHE flux upper limit of ∼1.2 × 10 −12 erg s −1 cm −2 in the 0.5–5.0 TeV range from W44 using data from the Very Energetic Radiation Imaging Telescope Array System. Our nondetection of W44 at VHE wavelengths is in agreement with observations from other imaging atmospheric Cherenkov telescopes and is perhaps consistent with the evolutionary stage of the SNR.

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Journal
The Astrophysical Journal
Published
2025-04-08
DOI
https://doi.org/10.3847/1538-4357/adc07d
Primary Topic
Astrophysics and Cosmic Phenomena
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article
Field-Weighted Citation Impact
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article

Constraints on the X-Ray and Very-high-energy Gamma-Ray Flux from Supernova Remnant W44

P. T. Reynolds, R. Shang, A. Archer, S. Feldman et al.
The Astrophysical Journal
Astrophysics and Cosmic Phenomena
article

Constraints on the X-Ray and Very-high-energy Gamma-Ray Flux from Supernova Remnant W44

P. T. Reynolds, R. Shang, A. Archer, S. Feldman, W. Hanlon, A. K. Talluri, D. Tak, T. K. Kleiner, Y. Chen, R. Mukherjee, P. Rabinowitz, J. L. Christiansen, M. J. Millard, M. Kherlakian, Jooyun Woo, J. H. Buckley, L. Fortson, N. Korzoun, M. J. Lang, M. Lundy, E. Pueschel, R. A. Ong, A. J. Chromey, W. Benbow, G. M. Foote, O. Hervet, Wei Ning, C. L. Mooney, D. Kieda, D. Ribeiro, J. Quinn, A. Furniss, J. V. Tucci, P. Bangale, J. T. Bartkoske, P. Moriarty, C. E. Hinrichs, Q. Feng, T. B. Humensky, S. Kumar, G. Maier, J. Holder, P. Kaaret, K. Ragan, M. Errando, D. A. Williams, M. N. Johnson, L. Saha, A. Duerr, M. Escobar Godoy, W. Jin, S. L. Wong, Sayan Kundu, M. Pohl, G. H. Sembroski, M. Kertzman, E. Roache, Marcos Santander
article en

Abstract

Abstract Observations of GeV gamma-ray emission from the well-studied mixed-morphology supernova remnant (SNR) W44 by Fermi-Large Area Telescope and AGILE imply that it is a site of significant cosmic-ray acceleration. The spectral energy distribution (SED) derived from the GeV data suggests that the gamma-ray emission likely originates from the decay of neutral pions generated by cosmic-ray interactions. It is essential to measure the SED of W44 in the X-ray and very-high-energy (VHE) gamma-ray bands to verify the hadronic origin of the emission and to gauge the potential contributions from leptonic emission. We report an upper limit of the nonthermal X-ray flux from W44 of 5 × 10 −13 erg cm −2 s −1 in the 0.5–8.0 keV band based on ∼300 ks of XMM-Newton observations. The X-ray upper limit is consistent with previously estimated hadronic models, but in tension with the leptonic models. We estimate the VHE flux upper limit of ∼1.2 × 10 −12 erg s −1 cm −2 in the 0.5–5.0 TeV range from W44 using data from the Very Energetic Radiation Imaging Telescope Array System. Our nondetection of W44 at VHE wavelengths is in agreement with observations from other imaging atmospheric Cherenkov telescopes and is perhaps consistent with the evolutionary stage of the SNR.

The Astrophysical JournalVol. 983(1)
University College Dublin (IE), Dartmouth College (US), DePauw University (US), University of Iowa (US), Marshall Space Flight Center (US), University of Minnesota (US), Goddard Space Flight Center (US), University of Indianapolis (US), Seoul National University (KR), California Polytechnic State University (US), University of California, Los Angeles (US), University of Alabama (US), University of Potsdam (DE), California State University, East Bay (US), University of California, Santa Cruz (US), Ollscoil na Gaillimhe – University of Galway (IE), Washington University in St. Louis (US), Purdue University West Lafayette (US), University of Utah (US), Munster Technological University (IE), Center for Astrophysics Harvard & Smithsonian (US), McGill University (CA), Indiana University – Purdue University Indianapolis (US), University of Maryland, College Park (US), Columbia University (US), University of Delaware (US), Ruhr University Bochum (DE), Barnard College (US)
National Science Foundation, Smithsonian Institution, U.S. Department of Energy, National Energy Research Scientific Computing Center, Office of Science, Natural Sciences and Engineering Research Council of Canada
Openalex Percentile: Top 96%
Astrophysics and Cosmic Phenomena
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