© C. Maitra, Haonan Yang / MPE
Einstein Probe satellite, a collaboration of, among others, the Max Planck Institute for Extraterrestrial Physics (MPE) and the Chinese Academy of Sciences (CAS), has captured an extraordinary celestial event: an X-ray outburst from a rare binary system. This discovery sheds new light on the evolution of massive stars and demonstrates the unique capabilities of Einstein Probe in detecting transient X-ray sources.
On 27 May 2024, the satellite’s Wide-field X-ray Telescope (WXT) detected an unusual X-ray source in the Small Magellanic Cloud (SMC). Follow-up observations, including those from NASA’s Swift and NICER telescopes and ESA’s XMM-Newton, confirmed the discovery: a rare pairing of a massive Be-type star and a dense white dwarf. This dynamic duo defies conventional expectations—while the Be star is still burning brightly, its companion has already collapsed into a white dwarf.
"This discovery uncovers an elusive class of object called Be white dwarf binaries (BeWDs). Binary evolution models predict that BeWDs should be about seven times more common than Be-neutron star (BeNS) systems. However, its detection is difficult due to the supersoft nature of the X-ray emission, which can be absorbed by the circumstellar disc of the Be star”, explains MPE scientist Chandreyee Maitra, who contributed to the interpretation of the results.
Haonan Yang, a PhD student at MPE and CAS who led the Einstein Probe data analysis of this object, adds: "The large Field of View of Einstein Probe’s Follow-up X-ray Telescope (EP FXT) allows efficient monitoring of the Magellanic Clouds, where such objects are expected to be detected in plentiful. Moreover, in collaboration with WXT, FXT can turn to a transient source within as little as 3 minutes after a new discovery, with a positioning accuracy better than 10 arcsec. FXT’s large effective area also ensures high sensitivity to low-energy photons, which is critical for probing supersoft sources."
His work highlights FXT’s capabilities in monitoring the nearby galaxies like the Magellanic Clouds, where such objects are expected to be abundant.
“The discovery of this source highlights the importance of soft X-ray surveys with EP FXT and WXT to uncover supersoft X-ray sources and novae. Moreover, the nova outburst from this system indicates the presence of a massive white dwarf close its maximum possible value, i.e., the Chandrasekhar limit. This can be instrumental in solving the debate on the progenitors of Supernova 1a”, says Chandreyee Maitra.
About Einstein Probe
Contact:
Dr. Chandreyee Maitra
Researcher in High-Energy Astrophysics Group
cmaitra@mpe.mpg.de
Max Planck Institute for Extraterrestrial Physics
Haonan Yang
PhD-student Highenergy group
tel: +49 89 30000-3347
hnyang@mpe.mpg.de
Max-Planck-Institut für extraterrestrische Physik, Garching
A. Marino, H. N. Yang, F. Coti Zelati, N. Rea, S. Guillot, G. K. Jaisawal, C. Maitra, et al.
Einstein Probe Discovery of EP J005245.1−722843: A Rare Be–White Dwarf Binary in the Small Magellanic Cloud?
ApJL 980 L36
Source | DOI
Einstein Probe detects puzzling cosmic explosion
January 23, 2025
On 27 May 2024, the satellite’s Wide-field X-ray Telescope (WXT) detected an unusual X-ray source in the Small Magellanic Cloud (SMC). Follow-up observations, including those from NASA’s Swift and NICER telescopes and ESA’s XMM-Newton, confirmed the discovery: a rare pairing of a massive Be-type star and a dense white dwarf. This dynamic duo defies conventional expectations—while the Be star is still burning brightly, its companion has already collapsed into a white dwarf.
"This discovery uncovers an elusive class of object called Be white dwarf binaries (BeWDs). Binary evolution models predict that BeWDs should be about seven times more common than Be-neutron star (BeNS) systems. However, its detection is difficult due to the supersoft nature of the X-ray emission, which can be absorbed by the circumstellar disc of the Be star”, explains MPE scientist Chandreyee Maitra, who contributed to the interpretation of the results.
Haonan Yang, a PhD student at MPE and CAS who led the Einstein Probe data analysis of this object, adds: "The large Field of View of Einstein Probe’s Follow-up X-ray Telescope (EP FXT) allows efficient monitoring of the Magellanic Clouds, where such objects are expected to be detected in plentiful. Moreover, in collaboration with WXT, FXT can turn to a transient source within as little as 3 minutes after a new discovery, with a positioning accuracy better than 10 arcsec. FXT’s large effective area also ensures high sensitivity to low-energy photons, which is critical for probing supersoft sources."
His work highlights FXT’s capabilities in monitoring the nearby galaxies like the Magellanic Clouds, where such objects are expected to be abundant.
“The discovery of this source highlights the importance of soft X-ray surveys with EP FXT and WXT to uncover supersoft X-ray sources and novae. Moreover, the nova outburst from this system indicates the presence of a massive white dwarf close its maximum possible value, i.e., the Chandrasekhar limit. This can be instrumental in solving the debate on the progenitors of Supernova 1a”, says Chandreyee Maitra.
About Einstein Probe
MPE played a key role in the development of Einstein Probe’s Follow-up X-ray Telescope (FXT), contributing advanced optics and detector technology. The institute provided one of the FXT’s mirror modules, repurposing a spare from its eROSITA X-ray telescope, and collaborated with ESA and industry partners to supply the second. MPE also developed the state-of-the-art pnCCD detector modules, leveraging its expertise in high-precision X-ray spectroscopy.
Contact:
Dr. Chandreyee Maitra
Researcher in High-Energy Astrophysics Group
cmaitra@mpe.mpg.de
Max Planck Institute for Extraterrestrial Physics
Haonan Yang
PhD-student Highenergy group
tel: +49 89 30000-3347
hnyang@mpe.mpg.de
Max-Planck-Institut für extraterrestrische Physik, Garching
A. Marino, H. N. Yang, F. Coti Zelati, N. Rea, S. Guillot, G. K. Jaisawal, C. Maitra, et al.
Einstein Probe Discovery of EP J005245.1−722843: A Rare Be–White Dwarf Binary in the Small Magellanic Cloud?
ApJL 980 L36
Source | DOI
Einstein Probe detects puzzling cosmic explosion
January 23, 2025
Einstein Probe has opened a new window onto the distant X-ray
Universe, promising new views of the most faraway explosions in the
cosmos. Less than three months after launch, the spacecraft already
discovered a puzzling blast of X-rays that could require a change the
way we explain the extraordinary explosions known as gamma-ray bursts.
