Study of Long-term Spectral Evolution and X-Ray and <i>γ</i>-Ray Correlation of Blazars Seen by HAWC

Abstract The HAWC Observatory collected 6 yr of extensive data, providing an ideal platform for long-term monitoring of blazars in the very high energy (VHE) band, without bias toward specific flux states. HAWC continuously monitors blazar activity at TeV energies, focusing on sources with a redshift of z ≤ 0.3, based on the Third Fermi-LAT Catalog of High-Energy sources. We specifically focused our analysis on Mrk 421 and Mrk 501, as they are the brightest blazars observed by the HAWC Observatory. With a data set of 2143 days, this work significantly extends the monitoring previously published, which was based on 511 days of observation. By utilizing HAWC data for the VHE γ -ray emission in the 300 GeV–100 TeV energy range, in conjunction with Swift-XRT data for the 0.3–10 keV X-ray emission, we aim to explore potential correlations between these two bands. For Mrk 501, we found evidence of a long-term correlation. Additionally, we identified a period in the light curve where the flux was very low for more than 2 yr. On the other hand, our analysis of Mrk 421 measured a strong linear correlation for quasi-simultaneous observations collected by HAWC and Swift-XRT. This result is consistent with a linear dependence and a multiple-zone synchrotron self-Compton model to explain the X-ray and γ -ray emission. Finally, as suggested by previous findings, we confirm a harder-when-brighter behavior in the spectral evolution of the flux properties for Mrk 421. These findings contribute to the understanding of blazar emissions and their underlying mechanisms.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-02-05
DOI
https://doi.org/10.3847/1538-4357/ad9d3d
Citations
2
Primary Topic
Astrophysics and Cosmic Phenomena
Type
article
Field-Weighted Citation Impact
3.74

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article

Study of Long-term Spectral Evolution and X-Ray and γ-Ray Correlation of Blazars Seen by HAWC

F. Ureña-Mena, Rishi Babu, E. Belmont‐Moreno, A. Lara et al.
2 citations
The Astrophysical Journal
Astrophysics and Cosmic Phenomena
3.74
article

Study of Long-term Spectral Evolution and X-Ray and γ-Ray Correlation of Blazars Seen by HAWC

F. Ureña-Mena, Rishi Babu, E. Belmont‐Moreno, A. Lara, C. Alvarez, Enrique Varela, K. Malone, A. Sandoval, A. Falcone, P. Miranda-Romagnoli, E. De la Fuente, U. Cotti, I. Herzog, A. Nayerhoda, J. C. Díaz–Vélez, Vikas Joshi, L. Villaseñor, M. R. Zapatero Osorio, L. Nellen, B. L. Dingus, José Erandi Serna-Franco, J. A. Goodman, O. Tibolla, E. Ruiz-Velasco, Mora Durocher, Y. Son, D. Avila Rojas, G. Luis-Raya, Fredric Hancock, E. G. Pérez‐Pérez, J. S. H. Lee, N. Di Lalla, M. Mostafá, D. Kieda, T. Capistrán, X. Wang, C. Espinoza, K. S. Caballero‐Mora, R. W. Springer, Chang Dong Rho, F. Garfias, D. Rosa‐González, R. Torres-Escobedo, A. L. Longinotti, Elijah Job Willox, F. Hueyotl‐Zahuantitla, A. Iriarte, M. A. DuVernois, D. Salazar-Gallegos, Hongyan Zhou, Amado Andrés, J. P. Harding, R. Alfaro, W.H. Lee, Katherine E. Whitaker, J. A. García-González, R. Noriega-Papaqui, J. Martínez-Castro, Israel Martinez-Castellanos, C. de León, K. Engel, Kwok Lung Fan, Rhiannon M. Turner, S. Hernández-Cadena, Davide Depaoli, H. A. Ayala Solares, S. Yun-Cárcamo, S. Fraija, A. Gonzalez Muñoz, Maria Magdalena González, H. Salazar, O. Martinez, A. Bernal, I. J. Watson, A.J. Smith, R. Diaz Hernandez, N. Fraija, M. U. Nisa, F. Carreón, E. Moreno, S. Kaufmann, H. León Vargas, K. Tollefson, I. Torres, Y. Pérez Araujo, M. Schneider, J. A. J. Matthews, J. C. Arteaga-Velázquez, N. Omodei, S. Coutiño de León, S. Casanova, J. Cotzomi, D. Huang, S. Groetsch, A. Carramiñana, J. A. Rodríguez Montes, J.T. Linnemann
article en
2 citations

Abstract

Abstract The HAWC Observatory collected 6 yr of extensive data, providing an ideal platform for long-term monitoring of blazars in the very high energy (VHE) band, without bias toward specific flux states. HAWC continuously monitors blazar activity at TeV energies, focusing on sources with a redshift of z ≤ 0.3, based on the Third Fermi-LAT Catalog of High-Energy sources. We specifically focused our analysis on Mrk 421 and Mrk 501, as they are the brightest blazars observed by the HAWC Observatory. With a data set of 2143 days, this work significantly extends the monitoring previously published, which was based on 511 days of observation. By utilizing HAWC data for the VHE γ -ray emission in the 300 GeV–100 TeV energy range, in conjunction with Swift-XRT data for the 0.3–10 keV X-ray emission, we aim to explore potential correlations between these two bands. For Mrk 501, we found evidence of a long-term correlation. Additionally, we identified a period in the light curve where the flux was very low for more than 2 yr. On the other hand, our analysis of Mrk 421 measured a strong linear correlation for quasi-simultaneous observations collected by HAWC and Swift-XRT. This result is consistent with a linear dependence and a multiple-zone synchrotron self-Compton model to explain the X-ray and γ -ray emission. Finally, as suggested by previous findings, we confirm a harder-when-brighter behavior in the spectral evolution of the flux properties for Mrk 421. These findings contribute to the understanding of blazar emissions and their underlying mechanisms.

The Astrophysical JournalVol. 980(1)
Consejo Nacional de Ciencia y Tecnología
Affordable and clean energy
Openalex Percentile: Top 9%
Astrophysics and Cosmic Phenomena
3.74
DOIOpen Access PDFOpenAlex
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