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Title: Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC

Abstract

In this study, we present TeV gamma-ray observations of the Crab Nebula, the standard reference source in ground-based gamma-ray astronomy, using data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use two independent energy estimation methods that utilize extensive air shower variables such as the core position, shower angle, and shower lateral energy distribution. In contrast, the previously published HAWC energy spectrum roughly estimated the shower energy with only the number of photomultipliers triggered. This new methodology yields a much-improved energy resolution over the previous analysis and extends HAWC's ability to accurately measure gamma-ray energies well beyond 100 TeV. The energy spectrum of the Crab Nebula is well fit to a log-parabola shape $$\left(\tfrac{{dN}}{{dE}}={\phi }_{0}{\left(E/7\mathrm{TeV}\right)}^{-\alpha -\beta \mathrm{ln}\left(E/7\mathrm{TeV}\right)}\right)$$ with emission up to at least 100 TeV. For the first estimator, a ground parameter that utilizes fits to the lateral distribution function to measure the charge density 40 m from the shower axis, the best-fit values are $${\phi }_{o}=(2.35\pm {0.04}_{-0.21}^{+0.20})\times {10}^{-13}$$ (TeV cm 2 s) -1, $$\alpha =2.79\pm {0.02}_{-0.03}^{+0.01}$$, and $$\beta =0.10\pm {0.01}_{-0.03}^{+0.01}$$. For the second estimator, a neural network that uses the charge distribution in annuli around the core and other variables, these values are $${\phi }_{o}=(2.31\pm {0.02}_{-0.17}^{+0.32})\times {10}^{-13}$$ (TeV cm 2 s) -1, $$\alpha =2.73\pm {0.02}_{-0.02}^{+0.03}$$, and β = 0.06 ± 0.01 ± 0.02. The first set of uncertainties is statistical; the second set is systematic. Both methods yield compatible results. Finally, these measurements are the highest-energy observation of a gamma-ray source to date.

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Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); USDOE Laboratory Directed Research and Development (LDRD) Program
Contributing Org.:
HAWC Collaboration
OSTI Identifier:
1565817
Report Number(s):
LA-UR-19-24703
Journal ID: ISSN 1538-4357
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 881; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; HAWC; gamma rays; Crab Nebula; acceleration of particles; astroparticle physics; gamma rays: general

Citation Formats

Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Camacho, J. R. Angeles, Arceo, R., Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Baghmanyan, V., Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, Fuente, E. De la, León, C. de, Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Espinoza, C., Fick, B., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Peisker, A., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tabachnick, E., Tanner, M., Tibolla, O., Tollefson, K., Torres, I., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Zepeda, A., and Zhou, H. Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC. United States: N. p., 2019. Web. doi:10.3847/1538-4357/ab2f7d.
Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Camacho, J. R. Angeles, Arceo, R., Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Baghmanyan, V., Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, Fuente, E. De la, León, C. de, Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Espinoza, C., Fick, B., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Peisker, A., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tabachnick, E., Tanner, M., Tibolla, O., Tollefson, K., Torres, I., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Zepeda, A., & Zhou, H. Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC. United States. doi:10.3847/1538-4357/ab2f7d.
Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Camacho, J. R. Angeles, Arceo, R., Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Baghmanyan, V., Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, Fuente, E. De la, León, C. de, Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Espinoza, C., Fick, B., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Peisker, A., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tabachnick, E., Tanner, M., Tibolla, O., Tollefson, K., Torres, I., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Zepeda, A., and Zhou, H. Wed . "Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC". United States. doi:10.3847/1538-4357/ab2f7d.
@article{osti_1565817,
title = {Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC},
author = {Abeysekara, A. U. and Albert, A. and Alfaro, R. and Alvarez, C. and Álvarez, J. D. and Camacho, J. R. Angeles and Arceo, R. and Arteaga-Velázquez, J. C. and Arunbabu, K. P. and Rojas, D. Avila and Solares, H. A. Ayala and Baghmanyan, V. and Belmont-Moreno, E. and BenZvi, S. Y. and Brisbois, C. and Caballero-Mora, K. S. and Capistrán, T. and Carramiñana, A. and Casanova, S. and Cotti, U. and Cotzomi, J. and de León, S. Coutiño and Fuente, E. De la and León, C. de and Dichiara, S. and Dingus, B. L. and DuVernois, M. A. and Díaz-Vélez, J. C. and Ellsworth, R. W. and Engel, K. and Espinoza, C. and Fick, B. and Fleischhack, H. and Fraija, N. and Galván-Gámez, A. and García-González, J. A. and Garfias, F. and González, M. M. and Goodman, J. A. and Harding, J. P. and Hernandez, S. and Hinton, J. and Hona, B. and Hueyotl-Zahuantitla, F. and Hui, C. M. and Hüntemeyer, P. and Iriarte, A. and Jardin-Blicq, A. and Joshi, V. and Kaufmann, S. and Kieda, D. and Lara, A. and Lee, W. H. and Vargas, H. León and Linnemann, J. T. and Longinotti, A. L. and Luis-Raya, G. and Lundeen, J. and Malone, K. and Marinelli, S. S. and Martinez, O. and Martinez-Castellanos, I. and Martínez-Castro, J. and Martínez-Huerta, H. and Matthews, J. A. and Miranda-Romagnoli, P. and Morales-Soto, J. A. and Moreno, E. and Mostafá, M. and Nayerhoda, A. and Nellen, L. and Newbold, M. and Nisa, M. U. and Noriega-Papaqui, R. and Peisker, A. and Pérez-Pérez, E. G. and Pretz, J. and Ren, Z. and Rho, C. D. and Rivière, C. and Rosa-González, D. and Rosenberg, M. and Ruiz-Velasco, E. and Salazar, H. and Greus, F. Salesa and Sandoval, A. and Schneider, M. and Schoorlemmer, H. and Arroyo, M. Seglar and Sinnis, G. and Smith, A. J. and Springer, R. W. and Surajbali, P. and Tabachnick, E. and Tanner, M. and Tibolla, O. and Tollefson, K. and Torres, I. and Weisgarber, T. and Westerhoff, S. and Wood, J. and Yapici, T. and Zepeda, A. and Zhou, H.},
abstractNote = {In this study, we present TeV gamma-ray observations of the Crab Nebula, the standard reference source in ground-based gamma-ray astronomy, using data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use two independent energy estimation methods that utilize extensive air shower variables such as the core position, shower angle, and shower lateral energy distribution. In contrast, the previously published HAWC energy spectrum roughly estimated the shower energy with only the number of photomultipliers triggered. This new methodology yields a much-improved energy resolution over the previous analysis and extends HAWC's ability to accurately measure gamma-ray energies well beyond 100 TeV. The energy spectrum of the Crab Nebula is well fit to a log-parabola shape $\left(\tfrac{{dN}}{{dE}}={\phi }_{0}{\left(E/7\mathrm{TeV}\right)}^{-\alpha -\beta \mathrm{ln}\left(E/7\mathrm{TeV}\right)}\right)$ with emission up to at least 100 TeV. For the first estimator, a ground parameter that utilizes fits to the lateral distribution function to measure the charge density 40 m from the shower axis, the best-fit values are ${\phi }_{o}=(2.35\pm {0.04}_{-0.21}^{+0.20})\times {10}^{-13}$ (TeV cm2 s)-1, $\alpha =2.79\pm {0.02}_{-0.03}^{+0.01}$, and $\beta =0.10\pm {0.01}_{-0.03}^{+0.01}$. For the second estimator, a neural network that uses the charge distribution in annuli around the core and other variables, these values are ${\phi }_{o}=(2.31\pm {0.02}_{-0.17}^{+0.32})\times {10}^{-13}$ (TeV cm2 s)-1, $\alpha =2.73\pm {0.02}_{-0.02}^{+0.03}$, and β = 0.06 ± 0.01 ± 0.02. The first set of uncertainties is statistical; the second set is systematic. Both methods yield compatible results. Finally, these measurements are the highest-energy observation of a gamma-ray source to date.},
doi = {10.3847/1538-4357/ab2f7d},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 881,
place = {United States},
year = {2019},
month = {8}
}

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