A new type-1 transition in NGC 1346 revealed by (spectro)polarimetry
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_ | 1866909685132558336 |
|---|---|
| author | Marin, F. Hutsemékers, D. Jorstad, S. |
| author_facet | Marin, F. Hutsemékers, D. Jorstad, S. |
| contents | We present the first photo- and spectropolarimetric observations of the changing-look active galactic nucleus NGC~1346 taken with the Perkins telescope (November 2022, March 2025) and VLT/FORS2 (August and September 2024), which have revealed a new spectral transition. We find that NGC~1346 has reverted to its former (2001) type-1 spectral state after having been a type-2 active galactic nucleus from 2004 to 2022. More and more intense broad H$β$ (3720 $\pm$ 310 km.s$^{-1}$ full width at half maximum) and H$α$ (2985 $\pm$ 230 km.s$^{-1}$) emission lines appeared between August and September 2024, suggesting that the broad-line region (BLR) is increasingly irradiated. The strong blueshift of the Balmer lines ($\sim$ 1600 km.s$^{-1}$) indicates that the gas is moving toward the observer, possibly due to a radiation-driven outflow. The strong difference between 2022's ($\sim$ 3\%) and 2024-2025's de-biased polarization ($\le$ 0.5\%), the blueing of the spectra between August and September 2024, and the slow rise in the integrated flux between 2022 and 2025 argue against asymmetric or temporary obscuration by a cloud passing in front of the line of sight. Two options, either a re-illumination of the BLR or a tidal disruption event, can explain the observed properties of NGC~1346. Timely follow-up observations taken while the phenomenon is still ongoing are needed to determine which of the two solutions is the correct one. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_08589 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A new type-1 transition in NGC 1346 revealed by (spectro)polarimetry Marin, F. Hutsemékers, D. Jorstad, S. Astrophysics of Galaxies 85-06 85-06 85-06 J.2.3; J.2.9 We present the first photo- and spectropolarimetric observations of the changing-look active galactic nucleus NGC~1346 taken with the Perkins telescope (November 2022, March 2025) and VLT/FORS2 (August and September 2024), which have revealed a new spectral transition. We find that NGC~1346 has reverted to its former (2001) type-1 spectral state after having been a type-2 active galactic nucleus from 2004 to 2022. More and more intense broad H$β$ (3720 $\pm$ 310 km.s$^{-1}$ full width at half maximum) and H$α$ (2985 $\pm$ 230 km.s$^{-1}$) emission lines appeared between August and September 2024, suggesting that the broad-line region (BLR) is increasingly irradiated. The strong blueshift of the Balmer lines ($\sim$ 1600 km.s$^{-1}$) indicates that the gas is moving toward the observer, possibly due to a radiation-driven outflow. The strong difference between 2022's ($\sim$ 3\%) and 2024-2025's de-biased polarization ($\le$ 0.5\%), the blueing of the spectra between August and September 2024, and the slow rise in the integrated flux between 2022 and 2025 argue against asymmetric or temporary obscuration by a cloud passing in front of the line of sight. Two options, either a re-illumination of the BLR or a tidal disruption event, can explain the observed properties of NGC~1346. Timely follow-up observations taken while the phenomenon is still ongoing are needed to determine which of the two solutions is the correct one. |
| title | A new type-1 transition in NGC 1346 revealed by (spectro)polarimetry |
| topic | Astrophysics of Galaxies 85-06 85-06 85-06 J.2.3; J.2.9 |
| url | https://arxiv.org/abs/2507.08589 |