Options
Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe
Journal
The Astrophysical Journal
Date Issued
2025-04-21
Author(s)
Mingjun Liu
Yijia Zhang
Yun Wang
Rui Xue
David Buckley
D. Andrew Howell
Chichuan Jin
Wenxiong Li
Itumeleng Monageng
Haiwu Pan
Ning-Chen Sun
Samaporn Tinyanont
Lingzhi Wang
Weimin Yuan
Jie An
Moira Andrews
Rungrit Anutarawiramkul
Pathompong Butpan
Yong Chen
Huaqing Cheng
Weiwei Cui
Cui-Yuan Dai
Lixin Dai
Joseph Farah
Hua Feng
Shaoyu Fu
Shumei Jia
Shuaiqing Jiang
An Li
Chengkui Li
Dongyue Li
Tianying Lian
Yifang Liang
Heyang Liu
Xing Liu
Yuan Liu
Jirong Mao
Curtis McCully
Megan Newsome
Estefania Padilla Gonzalez
Xin Pan
Xinxiang Sun
Giacomo Terreran
Ze-Rui Wang
Qinyu Wu
Hubing Xiao
Dingrong Xiong
Dong Xu
Xinpeng Xu
Suijian Xue
Haonan Yang
Jun Yang
Jin Zhang
Wenda Zhang
Wenjie Zhang
Hu Zou
Abstract
<jats:title>Abstract</jats:title>
<jats:p>Blazars are often observed to flare across multiple wavelengths. Orphan flares from blazars have only been detected a few times, providing an opportunity to understand the structure of the jet in the accreting system. We report a remarkable orphan X-ray flare from a blazar candidate EP240709a, detected by the Einstein Probe (EP) in July 2024. The multiband spectral properties and variability support EP240709a as a high-energy peaked BL Lacertae-type object. The flux in 0.5–10 keV increased by at least 28 times to the value of low state in 2020, with no significant flaring detected in other bands during the same period. EP240709a exhibits the harder-when-brighter tendency in the X-ray band during the orphan flare, while its infrared-optical spectra are featureless. We employ one-zone and two-zone leptonic synchrotron self-Compton models to perform the spectral energy distribution fitting. Detecting this rare orphan flare shows the potential of EP in discovering peculiar activities from AGN in high-cadence X-ray sky surveys.</jats:p>
<jats:p>Blazars are often observed to flare across multiple wavelengths. Orphan flares from blazars have only been detected a few times, providing an opportunity to understand the structure of the jet in the accreting system. We report a remarkable orphan X-ray flare from a blazar candidate EP240709a, detected by the Einstein Probe (EP) in July 2024. The multiband spectral properties and variability support EP240709a as a high-energy peaked BL Lacertae-type object. The flux in 0.5–10 keV increased by at least 28 times to the value of low state in 2020, with no significant flaring detected in other bands during the same period. EP240709a exhibits the harder-when-brighter tendency in the X-ray band during the orphan flare, while its infrared-optical spectra are featureless. We employ one-zone and two-zone leptonic synchrotron self-Compton models to perform the spectral energy distribution fitting. Detecting this rare orphan flare shows the potential of EP in discovering peculiar activities from AGN in high-cadence X-ray sky surveys.</jats:p>