_version_ 1866912705927970816
author Aryan, Amar
Chen, Ting-Wan
Yang, Sheng
Gillanders, James H.
Kong, Albert K. H.
Smartt, S. J.
Stevance, Heloise F.
Yang, Yi-Jung
Aamer, Aysha
Gupta, Rahul
Fan, Lele
Hou, Wei-Jie
Hsiao, Hsiang-Yao
Kumar, Amit
Lai, Cheng-Han
Lee, Meng-Han
Lee, Yu-Hsing
Lin, Hung-Chin
Lin, Chi-Sheng
Ngeow, Chow-Choong
Nicholl, Matt
Pan, Yen-Chen
Pandey, Shashi Bhushan
K, Aiswarya Sankar.
Srivastav, Shubham
Sun, Guanghui
Wang, Ze-Ning
author_facet Aryan, Amar
Chen, Ting-Wan
Yang, Sheng
Gillanders, James H.
Kong, Albert K. H.
Smartt, S. J.
Stevance, Heloise F.
Yang, Yi-Jung
Aamer, Aysha
Gupta, Rahul
Fan, Lele
Hou, Wei-Jie
Hsiao, Hsiang-Yao
Kumar, Amit
Lai, Cheng-Han
Lee, Meng-Han
Lee, Yu-Hsing
Lin, Hung-Chin
Lin, Chi-Sheng
Ngeow, Chow-Choong
Nicholl, Matt
Pan, Yen-Chen
Pandey, Shashi Bhushan
K, Aiswarya Sankar.
Srivastav, Shubham
Sun, Guanghui
Wang, Ze-Ning
contents The launch of the Einstein Probe (EP) mission has revolutionized the detection and follow-up observations of fast X-ray transients (FXTs) by providing prompt and timely access to their precise localizations. In the first year of its operation, the EP-mission reports the discovery of 72 high signal-to-noise FXTs. Subjected to the visibility in the sky and weather conditions, we search for the optical counterparts of 42 EP-discovered FXTs from the Lulin Observatory. We successfully detect the optical counterparts of 12 FXTs, and five of those are first discovered by us from the Lulin Observatory. We find that the optical counterparts are generally faint ($r>20$\,mag) and decline rapidly ($>0.5$\,mag per day). We also find that 12 out of 42 FXTs show direct evidence of their association with Gamma-Ray Bursts (GRBs) through significant temporal and spatial overlapping. Furthermore, the luminosities and redshifts of FXTs with confirmed optical counterparts in our observations are fully consistent with the faintest end of the GRB population. However, the non-detection of any associated optical counterpart with a significant fraction of FXTs suggests that EP FXTs are likely a subset of so-called `dark FXTs', similar to `dark GRBs'. Additionally, the luminosities of {\bf two FXTs with confirmed redshifts} are also consistent with jetted tidal disruption events (TDEs). However, we find that the optical luminosities of FXTs differ significantly from typical supernova shock breakout or kilonova emissions. Thus, we conclude that a significant fraction of EP-discovered FXTs are associated with events having relativistic jets; either a GRB or a jetted TDE.
format Preprint
id arxiv_https___arxiv_org_abs_2504_21096
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Search for the Optical Counterpart of Einstein Probe Discovered Fast X-ray Transients from Lulin Observatory
Aryan, Amar
Chen, Ting-Wan
Yang, Sheng
Gillanders, James H.
Kong, Albert K. H.
Smartt, S. J.
Stevance, Heloise F.
Yang, Yi-Jung
Aamer, Aysha
Gupta, Rahul
Fan, Lele
Hou, Wei-Jie
Hsiao, Hsiang-Yao
Kumar, Amit
Lai, Cheng-Han
Lee, Meng-Han
Lee, Yu-Hsing
Lin, Hung-Chin
Lin, Chi-Sheng
Ngeow, Chow-Choong
Nicholl, Matt
Pan, Yen-Chen
Pandey, Shashi Bhushan
K, Aiswarya Sankar.
Srivastav, Shubham
Sun, Guanghui
Wang, Ze-Ning
High Energy Astrophysical Phenomena
The launch of the Einstein Probe (EP) mission has revolutionized the detection and follow-up observations of fast X-ray transients (FXTs) by providing prompt and timely access to their precise localizations. In the first year of its operation, the EP-mission reports the discovery of 72 high signal-to-noise FXTs. Subjected to the visibility in the sky and weather conditions, we search for the optical counterparts of 42 EP-discovered FXTs from the Lulin Observatory. We successfully detect the optical counterparts of 12 FXTs, and five of those are first discovered by us from the Lulin Observatory. We find that the optical counterparts are generally faint ($r>20$\,mag) and decline rapidly ($>0.5$\,mag per day). We also find that 12 out of 42 FXTs show direct evidence of their association with Gamma-Ray Bursts (GRBs) through significant temporal and spatial overlapping. Furthermore, the luminosities and redshifts of FXTs with confirmed optical counterparts in our observations are fully consistent with the faintest end of the GRB population. However, the non-detection of any associated optical counterpart with a significant fraction of FXTs suggests that EP FXTs are likely a subset of so-called `dark FXTs', similar to `dark GRBs'. Additionally, the luminosities of {\bf two FXTs with confirmed redshifts} are also consistent with jetted tidal disruption events (TDEs). However, we find that the optical luminosities of FXTs differ significantly from typical supernova shock breakout or kilonova emissions. Thus, we conclude that a significant fraction of EP-discovered FXTs are associated with events having relativistic jets; either a GRB or a jetted TDE.
title Search for the Optical Counterpart of Einstein Probe Discovered Fast X-ray Transients from Lulin Observatory
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2504.21096