Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe

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; Zhen Guo; 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

doi:10.3847/1538-4357/adc301

Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe

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 ChengWeiwei Cui, Cui Yuan Dai, Lixin Dai, Joseph Farah, Hua Feng, Shaoyu Fu, Zhen Guo, 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

Research output: Contribution to journal › Article › peer-review

Abstract

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.

Original language	English
Article number	5
Journal	Astrophysical Journal
Volume	984
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/adc301
Publication status	Published - 1 May 2025
Externally published	Yes

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Liu, M., Zhang, Y., Wang, Y., Xue, R., Buckley, D., Howell, D. A., Jin, C., Li, W., Monageng, I., Pan, H., Sun, N. C., Tinyanont, S., Wang, L., Yuan, W., An, J., Andrews, M., Anutarawiramkul, R., Butpan, P., Chen, Y., ... Zou, H. (2025). Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe. Astrophysical Journal, 984(1), Article 5. https://doi.org/10.3847/1538-4357/adc301

@article{33138360ea664d92bcf8c4531ab1f359,

title = "Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe",

abstract = "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.",

author = "Mingjun Liu and Yijia Zhang and Yun Wang and Rui Xue and David Buckley and Howell, {D. Andrew} and Chichuan Jin and Wenxiong Li and Itumeleng Monageng and Haiwu Pan and Sun, {Ning Chen} and Samaporn Tinyanont and Lingzhi Wang and Weimin Yuan and Jie An and Moira Andrews and Rungrit Anutarawiramkul and Pathompong Butpan and Yong Chen and Huaqing Cheng and Weiwei Cui and Dai, {Cui Yuan} and Lixin Dai and Joseph Farah and Hua Feng and Shaoyu Fu and Zhen Guo and Shumei Jia and Shuaiqing Jiang and An Li and Chengkui Li and Dongyue Li and Tianying Lian and Yifang Liang and Heyang Liu and Xing Liu and Yuan Liu and Jirong Mao and Curtis McCully and Megan Newsome and {Padilla Gonzalez}, Estefania and Xin Pan and Xinxiang Sun and Giacomo Terreran and Wang, {Ze Rui} and Qinyu Wu and Hubing Xiao and Dingrong Xiong and Dong Xu and Xinpeng Xu and Suijian Xue and Haonan Yang and Jun Yang and Jin Zhang and Wenda Zhang and Wenjie Zhang and Hu Zou",

note = "Publisher Copyright: {\textcopyright} 2025. The Author(s). Published by the American Astronomical Society.",

year = "2025",

month = may,

day = "1",

doi = "10.3847/1538-4357/adc301",

language = "English",

volume = "984",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Liu, M, Zhang, Y, Wang, Y, Xue, R, Buckley, D, Howell, DA, Jin, C, Li, W, Monageng, I, Pan, H, Sun, NC, Tinyanont, S, Wang, L, Yuan, W, An, J, Andrews, M, Anutarawiramkul, R, Butpan, P, Chen, Y, Cheng, H, Cui, W, Dai, CY, Dai, L, Farah, J, Feng, H, Fu, S, Guo, Z, Jia, S, Jiang, S, Li, A, Li, C, Li, D, Lian, T, Liang, Y, Liu, H, Liu, X, Liu, Y, Mao, J, McCully, C, Newsome, M, Padilla Gonzalez, E, Pan, X, Sun, X, Terreran, G, Wang, ZR, Wu, Q, Xiao, H, Xiong, D, Xu, D, Xu, X, Xue, S, Yang, H, Yang, J, Zhang, J, Zhang, W, Zhang, W & Zou, H 2025, 'Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe', Astrophysical Journal, vol. 984, no. 1, 5. https://doi.org/10.3847/1538-4357/adc301

TY - JOUR

T1 - Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe

AU - Liu, Mingjun

AU - Zhang, Yijia

AU - Wang, Yun

AU - Xue, Rui

AU - Buckley, David

AU - Howell, D. Andrew

AU - Jin, Chichuan

AU - Li, Wenxiong

AU - Monageng, Itumeleng

AU - Pan, Haiwu

AU - Sun, Ning Chen

AU - Tinyanont, Samaporn

AU - Wang, Lingzhi

AU - Yuan, Weimin

AU - An, Jie

AU - Andrews, Moira

AU - Anutarawiramkul, Rungrit

AU - Butpan, Pathompong

AU - Chen, Yong

AU - Cheng, Huaqing

AU - Cui, Weiwei

AU - Dai, Cui Yuan

AU - Dai, Lixin

AU - Farah, Joseph

AU - Feng, Hua

AU - Fu, Shaoyu

AU - Guo, Zhen

AU - Jia, Shumei

AU - Jiang, Shuaiqing

AU - Li, An

AU - Li, Chengkui

AU - Li, Dongyue

AU - Lian, Tianying

AU - Liang, Yifang

AU - Liu, Heyang

AU - Liu, Xing

AU - Liu, Yuan

AU - Mao, Jirong

AU - McCully, Curtis

AU - Newsome, Megan

AU - Padilla Gonzalez, Estefania

AU - Pan, Xin

AU - Sun, Xinxiang

AU - Terreran, Giacomo

AU - Wang, Ze Rui

AU - Wu, Qinyu

AU - Xiao, Hubing

AU - Xiong, Dingrong

AU - Xu, Dong

AU - Xu, Xinpeng

AU - Xue, Suijian

AU - Yang, Haonan

AU - Yang, Jun

AU - Zhang, Jin

AU - Zhang, Wenda

AU - Zhang, Wenjie

AU - Zou, Hu

PY - 2025/5/1

Y1 - 2025/5/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=105003580997&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/adc301

DO - 10.3847/1538-4357/adc301

M3 - Article

AN - SCOPUS:105003580997

SN - 0004-637X

VL - 984

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 5

ER -

Detection of an Orphan X-Ray Flare from a Blazar Candidate EP240709a with the Einstein Probe

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