Magnetic Atmospheres and Circumstellar Interaction in J1901+1458: Revisiting the Most Compact White Dwarf Merger Remnant in the light of new UV and X-ray data
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866918135032971264 |
|---|---|
| author | Desai, Aayush Caiazzo, Ilaria Vennes, Stephane Kawka, Adela Cunningham, Tim Kotiwale, Gauri Cristea, Andrei A. Raymond, John C. Camisassa, Maria Althaus, Leandro G. Hermes, J. J. Traulsen, Iris Fuller, James Heyl, Jeremy van Roestel, Jan Burdge, Kevin B. Rodriguez, Antonio C. Pelisoli, Ingrid Gänsicke, Boris T. Szkody, Paula Maheshwari, Sumit K. Vanderbosch, Zachary P. Drake, Andrew Ferrario, Lilia Wickramasinghe, Dayal Justham, Stephen Pakmor, Ruediger El-Badry, Kareem Prince, Thomas Kulkarni, S. R. Graham, Matthew J. Rusholme, Ben Laher, Russ R. Purdum, Josiah |
| author_facet | Desai, Aayush Caiazzo, Ilaria Vennes, Stephane Kawka, Adela Cunningham, Tim Kotiwale, Gauri Cristea, Andrei A. Raymond, John C. Camisassa, Maria Althaus, Leandro G. Hermes, J. J. Traulsen, Iris Fuller, James Heyl, Jeremy van Roestel, Jan Burdge, Kevin B. Rodriguez, Antonio C. Pelisoli, Ingrid Gänsicke, Boris T. Szkody, Paula Maheshwari, Sumit K. Vanderbosch, Zachary P. Drake, Andrew Ferrario, Lilia Wickramasinghe, Dayal Justham, Stephen Pakmor, Ruediger El-Badry, Kareem Prince, Thomas Kulkarni, S. R. Graham, Matthew J. Rusholme, Ben Laher, Russ R. Purdum, Josiah |
| contents | Double degenerate white dwarf (WD) mergers can exhibit extreme magnetic fields exceeding $10^{8}$ G and rapid rotation, but their spectral-energy distributions and high-energy emission mechanisms remain poorly characterised. ZTF J1901+1458 stands out as the most compact and strongly magnetised object discovered in this class to date. Recent Chandra observations have revealed that the white dwarf is also a source of soft X-ray emission, inconsistent with a photospheric origin. We analyse new phase resolved UV spectroscopy from the HST combined with optical and near-infrared photometry and spectroscopy, with newly developed magnetic atmosphere models to determine its effective temperature, radius, mass, average surface magnetic field strength, and cooling age. Our results demonstrate that the spectral break at $\approx$3000 Å, observed in several highly magnetised WDs, is well-reproduced by our new models, which take into account the effect of magnetic opacities on the structure of the atmosphere. Our best-fit parameters for the WD yield an effective temperature ($T_{\rm{eff}}=28,015\pm 20$ K) and larger radius ($2630\pm10$ km) than previously reported. Furthermore, the near-infrared data exclude the presence of a stellar or brown dwarf companion hotter than $\approx$700 K. We also jointly analyse the previously published Chandra data and new XMM-Newton X-ray spectra. The faint X-ray emission, $L_X =(1.3\pm0.2)\times10^{27}$ erg/s is very soft and highly pulsed on the rotation period of the WD. We suggest that the X-rays are powered by accretion or via the interaction of the WD magnetosphere with CSM. If the rapidly rotating magnetic field could power a weak wind along open field lines, material could be extracted directly from the surface of the WD. Alternatively, accretion of fallback material from the merger or the tidal disruption of a planetary body are possible sources of CSM. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_03216 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Magnetic Atmospheres and Circumstellar Interaction in J1901+1458: Revisiting the Most Compact White Dwarf Merger Remnant in the light of new UV and X-ray data Desai, Aayush Caiazzo, Ilaria Vennes, Stephane Kawka, Adela Cunningham, Tim Kotiwale, Gauri Cristea, Andrei A. Raymond, John C. Camisassa, Maria Althaus, Leandro G. Hermes, J. J. Traulsen, Iris Fuller, James Heyl, Jeremy van Roestel, Jan Burdge, Kevin B. Rodriguez, Antonio C. Pelisoli, Ingrid Gänsicke, Boris T. Szkody, Paula Maheshwari, Sumit K. Vanderbosch, Zachary P. Drake, Andrew Ferrario, Lilia Wickramasinghe, Dayal Justham, Stephen Pakmor, Ruediger El-Badry, Kareem Prince, Thomas Kulkarni, S. R. Graham, Matthew J. Rusholme, Ben Laher, Russ R. Purdum, Josiah Solar and Stellar Astrophysics High Energy Astrophysical Phenomena Double degenerate white dwarf (WD) mergers can exhibit extreme magnetic fields exceeding $10^{8}$ G and rapid rotation, but their spectral-energy distributions and high-energy emission mechanisms remain poorly characterised. ZTF J1901+1458 stands out as the most compact and strongly magnetised object discovered in this class to date. Recent Chandra observations have revealed that the white dwarf is also a source of soft X-ray emission, inconsistent with a photospheric origin. We analyse new phase resolved UV spectroscopy from the HST combined with optical and near-infrared photometry and spectroscopy, with newly developed magnetic atmosphere models to determine its effective temperature, radius, mass, average surface magnetic field strength, and cooling age. Our results demonstrate that the spectral break at $\approx$3000 Å, observed in several highly magnetised WDs, is well-reproduced by our new models, which take into account the effect of magnetic opacities on the structure of the atmosphere. Our best-fit parameters for the WD yield an effective temperature ($T_{\rm{eff}}=28,015\pm 20$ K) and larger radius ($2630\pm10$ km) than previously reported. Furthermore, the near-infrared data exclude the presence of a stellar or brown dwarf companion hotter than $\approx$700 K. We also jointly analyse the previously published Chandra data and new XMM-Newton X-ray spectra. The faint X-ray emission, $L_X =(1.3\pm0.2)\times10^{27}$ erg/s is very soft and highly pulsed on the rotation period of the WD. We suggest that the X-rays are powered by accretion or via the interaction of the WD magnetosphere with CSM. If the rapidly rotating magnetic field could power a weak wind along open field lines, material could be extracted directly from the surface of the WD. Alternatively, accretion of fallback material from the merger or the tidal disruption of a planetary body are possible sources of CSM. |
| title | Magnetic Atmospheres and Circumstellar Interaction in J1901+1458: Revisiting the Most Compact White Dwarf Merger Remnant in the light of new UV and X-ray data |
| topic | Solar and Stellar Astrophysics High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2509.03216 |