The rise and decline of a transient obscuration event in a moderately distant type-I quasar
Abstract
Outflows of ionised material, often dubbed warm absorbers (WAs), are common in nearby Seyferts but sparse in distant and more energetic quasars (QSOs). We present multi-epoch X-ray and optical observations of the serendipitously identified type-I QSO 2MASS J14302580+4159572 at a redshift of z=0.35, revealing the rare rise and decline of a transient ionised absorber over a 22-year timescale. The discovery observations were obtained with XMM-Newton between 2002 and 2005. The first two observations show unremarkable X-ray spectra typical of unobscured type-I QSOs, whereas the 2005 observation reveals a pronounced suppression of the spectrum below ∼3 keV. Spectral analysis shows that this event is produced by a moderately ionised absorber with column density NH≃5×1022 cm−2 and ionisation parameter logξ≃1.4. Joint analysis of XMM-Newton, NuSTAR, and Swift/XRT observations spanning 22 years indicates that the absorber remained stable for nearly 18 years before weakening in the 2023--2024 Swift/XRT data. Throughout this period, the intrinsic 3--10 keV continuum remained remarkably stable, indicating that the observed variability is driven by changes in line-of-sight ionised absorption rather than intrinsic luminosity fluctuations. We interpret the event as a thermally driven ionised outflow located outside the broad-line region (BLR), at sub-parsec to parsec scales, with a density of order 106 cm−3. Supporting this scenario, the high-ionisation [O\,III] λ4363 emission line varies in tandem with the X-ray absorption, suggesting that the outflow progressively modifies the ionisation state of the inner narrow-line region (NLR) on decadal timescales. These observations provide a rare view of the long-term evolution of a quasar warm absorber and its impact on the circumnuclear environment.
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BibTeX
@misc{akylas2026rise,
title = {{The rise and decline of a transient obscuration event in a moderately distant type-I quasar}},
author = {A. Akylas and A. Georgakakis and E. Pouliasis and I. Georgantopoulos and C. Ricci and M. Chira and A. Ruiz and E. M. Xilouris},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.19910},
eprint = {2609.19910},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.19910},
}
RIS
TY - UNPB
TI - The rise and decline of a transient obscuration event in a moderately distant type-I quasar
AU - A. Akylas
AU - A. Georgakakis
AU - E. Pouliasis
AU - I. Georgantopoulos
AU - C. Ricci
AU - M. Chira
AU - A. Ruiz
AU - E. M. Xilouris
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.19910
UR - https://arxiv.org/abs/2609.19910
AB - Outflows of ionised material, often dubbed warm absorbers (WAs), are common in nearby Seyferts but sparse in distant and more energetic quasars (QSOs). We present multi-epoch X-ray and optical observations of the serendipitously identified type-I QSO 2MASS J14302580+4159572 at a redshift of z=0.35, revealing the rare rise and decline of a transient ionised absorber over a 22-year timescale. The discovery observations were obtained with XMM-Newton between 2002 and 2005. The first two observations show unremarkable X-ray spectra typical of unobscured type-I QSOs, whereas the 2005 observation reveals a pronounced suppression of the spectrum below ∼3 keV. Spectral analysis shows that this event is produced by a moderately ionised absorber with column density N_H≃5×10^22 cm^−2 and ionisation parameter logξ≃1.4. Joint analysis of XMM-Newton, NuSTAR, and Swift/XRT observations spanning 22 years indicates that the absorber remained stable for nearly 18 years before weakening in the 2023--2024 Swift/XRT data. Throughout this period, the intrinsic 3--10 keV continuum remained remarkably stable, indicating that the observed variability is driven by changes in line-of-sight ionised absorption rather than intrinsic luminosity fluctuations. We interpret the event as a thermally driven ionised outflow located outside the broad-line region (BLR), at sub-parsec to parsec scales, with a density of order 10^6 cm^−3. Supporting this scenario, the high-ionisation [O\,III] λ4363 emission line varies in tandem with the X-ray absorption, suggesting that the outflow progressively modifies the ionisation state of the inner narrow-line region (NLR) on decadal timescales. These observations provide a rare view of the long-term evolution of a quasar warm absorber and its impact on the circumnuclear environment.
ER -