LHAASO Observations of Mrk 421 during 2021 March–2024 March: A Comprehensive Very-high-energy Catalog of Multitimescale Outbursts and Its Time-averaged Behavior

Issued Date

2026-08-01

Resource Type

Article

ISSN

00670049

eISSN

15384365

DOI

10.3847/1538-4365/ae76cc

Scopus ID

2-s2.0-105044473337

Journal Title

Astrophysical Journal Supplement Series

Volume

285

Issue

2

Rights Holder(s)

SCOPUS

Bibliographic Citation

Astrophysical Journal Supplement Series Vol.285 No.2 (2026)

Suggested Citation

Cao Z., Aharonian F., Bai Y.X., Bao Y.W., Bastieri D., Bi X.J., Bi Y.J., Bian W., Blunier J., Bukevich A.V., Cai C.M., Cai Y.Y., Cao W.Y., Cao Z., Chang J., Chang J.F., Chen E.S., Chen G.H., Chen H.K., Chen L.F., Chen L., Chen L., Chen M.J., Chen M.L., Chen Q.H., Chen S., Chen S.H., Chen S.Z., Chen T.L., Chen X.B., Chen X.J., Chen X.P., Chen Y., Cheng N., Cheng Q.Y., Cheng Y.D., Cui M.Y., Cui S.W., Cui X.H., Cui Y.D., Dai B.Z., Dai H.L., Dai Z.G., Danzengluobu, Diao Y.X., Dong A.J., Dong X.Q., Duan K.K., Fan J.H., Fan Y.Z., Fang J., Fang J.H., Fang K., Feng C.F., Feng H., Feng L., Feng S.H., Feng X.T., Feng Y., Feng Y.L., Gabici S., Gao B., Gao Q., Gao W., Gao W.K., Ge M.M., Ge T.T., Geng L.S., Giacinti G., Gong G.H., Gou Q.B., Gu M.H., Guo F.L., Guo J., Guo K.J., Guo X.L., Guo Y.Q., Guo Y.Y., Han R.P., Hannuksela O.A., Hasan M., He H.H., He H.N., He J.Y., He X.Y., He Y., Hernández-Cadena S., Hou B.W., Hou C., Hou X., Hu H.B., Hu S.C., Huang C., Huang D.H., Huang J.J., Huang X.L., Huang X.T., Huang X.Y., Huang Y., Huang Y.Y. LHAASO Observations of Mrk 421 during 2021 March–2024 March: A Comprehensive Very-high-energy Catalog of Multitimescale Outbursts and Its Time-averaged Behavior. Astrophysical Journal Supplement Series Vol.285 No.2 (2026). doi:10.3847/1538-4365/ae76cc Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/118035

Title

LHAASO Observations of Mrk 421 during 2021 March–2024 March: A Comprehensive Very-high-energy Catalog of Multitimescale Outbursts and Its Time-averaged Behavior

Author(s)

Cao Z.
 Aharonian F.
 Bai Y.X.
 Bao Y.W.
 Bastieri D.
 Bi X.J.
 Bi Y.J.
 Bian W.
 Blunier J.
 Bukevich A.V.
 Cai C.M.
 Cai Y.Y.
 Cao W.Y.
 Cao Z.
 Chang J.
 Chang J.F.
 Chen E.S.
 Chen G.H.
 Chen H.K.
 Chen L.F.
 Chen L.
 Chen L.
 Chen M.J.
 Chen M.L.
 Chen Q.H.
 Chen S.
 Chen S.H.
 Chen S.Z.
 Chen T.L.
 Chen X.B.
 Chen X.J.
 Chen X.P.
 Chen Y.
 Cheng N.
 Cheng Q.Y.
 Cheng Y.D.
 Cui M.Y.
 Cui S.W.
 Cui X.H.
 Cui Y.D.
 Dai B.Z.
 Dai H.L.
 Dai Z.G.
 Danzengluobu
 Diao Y.X.
 Dong A.J.
 Dong X.Q.
 Duan K.K.
 Fan J.H.
 Fan Y.Z.
 Fang J.
 Fang J.H.
 Fang K.
 Feng C.F.
 Feng H.
 Feng L.
 Feng S.H.
 Feng X.T.
 Feng Y.
 Feng Y.L.
 Gabici S.
 Gao B.
 Gao Q.
 Gao W.
 Gao W.K.
 Ge M.M.
 Ge T.T.
 Geng L.S.
 Giacinti G.
 Gong G.H.
 Gou Q.B.
 Gu M.H.
 Guo F.L.
 Guo J.
 Guo K.J.
 Guo X.L.
 Guo Y.Q.
 Guo Y.Y.
 Han R.P.
 Hannuksela O.A.
 Hasan M.
 He H.H.
 He H.N.
 He J.Y.
 He X.Y.
 He Y.
 Hernández-Cadena S.
 Hou B.W.
 Hou C.
 Hou X.
 Hu H.B.
 Hu S.C.
 Huang C.
 Huang D.H.
 Huang J.J.
 Huang X.L.
 Huang X.T.
 Huang X.Y.
 Huang Y.
 Huang Y.Y.

Author's Affiliation

University of Chinese Academy of Sciences
 Tsinghua University
 Shanghai Jiao Tong University
 Sun Yat-Sen University
 University of Science and Technology of China
 Université Paris Cité
 Shandong University
 Nanjing University
 Chinese University of Hong Kong
 Southwest Jiaotong University
 Yunnan University
 Guangzhou University
 Institute of High Energy Physics, Chinese Academy of Sciences
 National Astronomical Observatories Chinese Academy of Sciences
 Hebei Normal University
 Max-Planck-Institut für Kernphysik
 Institute for Nuclear Research of the Russian Academy of Sciences
 Guizhou Normal University
 Yerevan State University
 China Center of Advanced Science and Technology World Laboratory
 Zhejiang Lab
 Purple Mountain Observatory Chinese Academy of Sciences
 Shanghai Astronomical Observatory Chinese Academy of Sciences
 Yunnan Observatories
 Tibet University
 State Key Laboratory of Particle Detection & Electronics
 TIANFU Cosmic Ray Research Center

Corresponding Author(s)

Cao Z.

Other Contributor(s)

Mahidol University

Abstract

The Large High Altitude Air Shower Observatory (LHAASO) monitors sources within its field of view for up to 7 hr daily, achieving a duty cycle exceeding 98% and an annual point-source sensitivity of 1.5% Crab units (CU) in the very-high-energy (VHE) band. This unbiased sky-survey mode facilitates systematic monitoring and investigation of outburst phenomena. In this paper, we present results from an unprecedented 3 yr monitoring campaign (2021 March–2024 March) of Markarian 421 (Mrk 421) using LHAASO, spanning energies from 0.4 to 20 TeV. We find that the blazar stayed in a quiescent state in 2021 and became active starting in 2022 with a total of 23 VHE outburst events identified, where the highest observed daily significance reaches 20σ with a flux equivalent to approximately 3.3 CU. LHAASO’s continuous monitoring suggests the flaring occupancy of Mrk 421 to be around 14%. During long-term monitoring, multiwavelength (MWL) variability and correlation analyses are conducted using complementary data from the Fermi Large Area Telescope, Monitor of All-sky X-ray Image Gas Slit Camera, the Neil Gehrels Swift Observatory X-Ray Telescope, and the Zwicky Transient Facility. A significant correlation (>3σ) is observed between the X-ray and VHE bands with no detectable time lag, while the correlation between the GeV and TeV bands is weaker. The energy spectrum of the TeV emission during the quiescent state is different from that in the active state, implying the existence of two modes of energy dissipation in the blazar jet. Using simultaneous MWL data, we also analyzed both the long-term and outburst-period spectral energy distributions, and discussed the possible origin of the outburst events.

Keyword(s)

Earth and Planetary Sciences
 Physics and Astronomy

Availability

URI

https://repository.li.mahidol.ac.th/handle/123456789/118035

Collections

Scopus 2026