An in-depth study of Gamma rays from the Starburst Galaxy M 82 with VERITAS

Document detail

ID

oai:arXiv.org:2501.09998

Topic

Astrophysics - High Energy Astroph...

Author

Acharyya, Atreya Adams, Colin B. Bangale, Priyadarshini Bartkoske, Joshua T. Benbow, Wystan Chen, Yu Christiansen, Jodi L. Chromey, Alisha J. Duerr, Anne Errando, Manel Godoy, Miguel E. Falcone, Abe Feldman, Sydney Feng, Qi Foote, Juniper Fortson, Lucy Furniss, Amy Hanlon, William Hanna, David Hervet, Olivier Hinrichs, Claire E. Holder, Jamie Humensky, Thomas B. Jin, Weidong Johnson, Madalyn N. Kaaret, Philip Kertzman, Mary Kherlakian, Maria Kieda, David Kleiner, Tobias K. Korzoun, Nikolas Krennrich, Frank Kumar, Sajan Lang, Mark J. Lundy, Matthew Maier, Gernot Millard, Matthew J. Mooney, Connor L. Moriarty, Patrick Mukherjee, Reshmi Ning, Wenmeng Brien, Stephan Ó Ong, Rene A. Pohl, Martin Pueschel, Elisa Quinn, John Rabinowitz, Pazit L. Ragan, Kenneth J. Reynolds, Paul T. Ribeiro, Deivid Roache, Emmet Sadeh, Iftach Saha, Lab Santander, Marcos Sembroski, Glenn H. Shang, Ruo Splettstoesser, Megan Talluri, Anjana K. Tucci, James V. Vassiliev, Vladimir V. Williams, David A. Wong, Samantha L. Woo, Jooyun

Year

2025

listing date

1/22/2025

Keywords

cosmic data 82 energy vhe starburst veritas

Metrics

Abstract

Assuming Galactic cosmic rays originate in supernovae and the winds of massive stars, starburst galaxies should produce very-high-energy (VHE; E$>$100 GeV) gamma-ray emission via the interaction of their copious quantities of cosmic rays with the large reservoirs of dense gas within the galaxies.

Such VHE emission was detected by VERITAS from the starburst galaxy M 82 in 2008-09.

An extensive, multi-year campaign followed these initial observations, yielding a total of 254 h of good quality VERITAS data on M 82.

Leveraging modern analysis techniques and the larger exposure, these VERITAS data show a more statistically significant VHE signal ($\sim$6.5 standard deviations ($\sigma$)).

The corresponding photon spectrum is well fit by a power law ($\Gamma = 2.3 \pm 0.3_{stat} \pm0.2_{sys}$) and the observed integral flux is F($>$450 GeV) = $(3.2 \pm0.6_{stat} \pm 0.6_{sys}) \times 10^{-13}~\mathrm{cm^{-2}~s}^{-1}$, or $\sim$0.4\% of the Crab Nebula flux above the same energy threshold.

The improved VERITAS measurements, when combined with various multi-wavelength data, enable modeling of the underlying emission and transport processes.

A purely leptonic scenario is found to be a poor representation of the gamma-ray spectral energy distribution (SED).

A lepto-hadronic scenario with cosmic rays following a power-law spectrum in momentum (index $s\simeq 2.25$), and with significant bremsstrahlung below $1$~GeV, provides a good match to the observed SED.

The synchrotron emission from the secondary electrons indicates that efficient non-radiative losses of cosmic-ray electrons may be related to advective escape from the starburst core.

;Comment: 15 pages, 7 figures; Accepted for the publication in The Astrophysical Journal (ApJ)

Acharyya, Atreya,Adams, Colin B.,Bangale, Priyadarshini,Bartkoske, Joshua T.,Benbow, Wystan,Chen, Yu,Christiansen, Jodi L.,Chromey, Alisha J.,Duerr, Anne,Errando, Manel,Godoy, Miguel E.,Falcone, Abe,Feldman, Sydney,Feng, Qi,Foote, Juniper,Fortson, Lucy,Furniss, Amy,Hanlon, William,Hanna, David,Hervet, Olivier,Hinrichs, Claire E.,Holder, Jamie,Humensky, Thomas B.,Jin, Weidong,Johnson, Madalyn N.,Kaaret, Philip,Kertzman, Mary,Kherlakian, Maria,Kieda, David,Kleiner, Tobias K.,Korzoun, Nikolas,Krennrich, Frank,Kumar, Sajan,Lang, Mark J.,Lundy, Matthew,Maier, Gernot,Millard, Matthew J.,Mooney, Connor L.,Moriarty, Patrick,Mukherjee, Reshmi,Ning, Wenmeng,Brien, Stephan Ó,Ong, Rene A.,Pohl, Martin,Pueschel, Elisa,Quinn, John,Rabinowitz, Pazit L.,Ragan, Kenneth J.,Reynolds, Paul T.,Ribeiro, Deivid,Roache, Emmet,Sadeh, Iftach,Saha, Lab,Santander, Marcos,Sembroski, Glenn H.,Shang, Ruo,Splettstoesser, Megan,Talluri, Anjana K.,Tucci, James V.,Vassiliev, Vladimir V.,Williams, David A.,Wong, Samantha L.,Woo, Jooyun, 2025, An in-depth study of Gamma rays from the Starburst Galaxy M 82 with VERITAS