Monthly Notices of the Royal Astronomical Society · 2024
Hubble Space Telescope Observations of Nearby Type 1 Quasars · Paper I
MNRAS 535, 621-633 (2024)
![Montage of continuum-subtracted Hubble [O III] images for all seven type 1 quasars in the study: PG 0026+129, PG 0052+251, PG 0157+001, PG 0953+414, PG 1012+008, PG 1049−005, and PG 1307+085.](/images/publications/hubble-space-telescope-observations-of-extended-o-iii-5007-emission-in-local-qso/all-targets-montage.webp)
Scientific summary
Hubble ACS narrow-band imaging measures the extent and morphology of [O III] λ5007 emission in seven nearby radio-quiet type 1 quasars at approximately 200 pc resolution. The analysis compares their ionized-gas distributions and size-luminosity behavior with luminous type 2 quasars to test how obscuration and circumnuclear gas structure differ between the populations.
Key results
Extended [O III] narrow-line regions are detected in all seven quasars, spanning approximately 3-9 kpc. Four have roughly symmetric morphologies, with axis ratios of 1.2-1.5, while three are asymmetric, with axis ratios of 2.4-5.6.
For the combined type 1 and type 2 AGN samples, the [O III] extent scales approximately as R[O III] ∝ L[O III]⁰·⁵, consistent with photoionization. Separate fits give slopes of 0.57 ± 0.05 for type 1 AGN and 0.48 ± 0.02 for type 2 AGN.
Photoionization-based maximum-size estimates agree with the type 2 quasar measurements but underestimate the type 1 quasar extents when the ionizing luminosity is inferred from [O III]. Using 5100 Å continuum luminosities improves the agreement for the type 1 sample.
The radial mass profiles contain extended [O III]-emitting gas in every target but less ionized gas near the nucleus than in the comparison type 2 quasars. A later evolutionary stage is a possible interpretation, not a directly observed temporal progression.
Connected research series
Three studies build a common observational picture of how ionized gas, hot X-ray winds, and circumnuclear clearing may be connected across luminous quasars.
Resolved [O III] gas masses, outflow rates, and energetics for the 12 type 2 quasars.
More extended but less massive [O III] regions motivate a later, more cleared phase.
Chandra and Hubble observations connect hot-wind coupling to a proposed clearing sequence.
Proposed physical context
Interpretive framework. This sequence connects measurements across different quasars; it does not trace individual systems evolving with time.
