Masatoshi Imanishi

We present the first spatially resolved kinematic evidence for dust in the outflows of Active Galactic Nuclei (AGN). We utilise observations from JWST with NIRSpec IFU and MIRI MRS data of 10 local Seyferts and use Principal Component Analysis (PCA) tomography to extract the kinematics of Polycyclic Aromatic Hydrocarbon (PAH) features. PAHs comprise the smallest carbonaceous dust molecules in the Interstellar Medium (ISM), and produce emission features in the infrared providing the potential to measure kinematics. This is however challenging due to their broad shapes and variations in their intrinsic profile, prompting the need for techniques such as PCA tomography. We find that the velocity of the PAHs is similar to the molecular gas as traced by the rotational transitions of H2, where for NGC 5728 and NGC 7582, both disk and outflow are present. We detect the outflow in the kinematics of large and neutral PAHs, namely the 11.3 μm and 17 μm PAH features, where after subtracting the disk, the velocity field matches that of high-ionisation potential lines such as [NeVI] (7.65 μm, IP = 158 eV). Finally, we fail to detect kinematics of the 6.2 μm PAH due to an altered intrinsic profile while the the 3.3 μm PAH kinematics purely trace the circumnuclear disk. This suggests the PAHs in the outflow are more neutral and larger than in star-forming regions, consistent with PAH band ratios in previous studies of AGN.

We present the results of our investigations of spectrally and spatially resolved (sub)millimeter HCN-to-HCO ⁺ flux ratios at J = 2–1, J = 3–2, and/or J = 4–3 in 18 nearby ( z < 0.15) ultraluminous infrared galaxies (ULIRGs), using ALMA ≲ 0 . ″ 2 (≲ 500 pc) resolution data. The geometry of elevated HCN-to-HCO ⁺ flux ratios (with >3 σ detections for both molecular lines) in position-position-velocity (PPV) space is visually classified into (i) a spherical shell (spectrally and spatially distinct), (ii) spectrally distinct and spatially compact, and (iii) filled (spectrally filled and spatially compact). These can naturally be explained by the elevation of the flux ratio due to (i) a spatially resolved outflow, (ii) an active galactic nucleus (AGN) and/or a spatially unresolved outflow with blueshifted and redshifted emission components, and (iii) an AGN and/or a spatially confined outflow with not clearly separated blueshifted and redshifted velocity components, respectively. Signatures of elevated HCN-to-HCO ⁺ flux ratios originated from (a) spatially resolved outflow and (b) AGN and/or spatially unresolved outflow are seen in seven and nine ULIRGs, respectively. In the former spatially resolved outflow-origin case, modest-velocity components relative to the maximum outflow velocity tend to be probed by spaxels with elevated HCN-to-HCO ⁺ flux ratios. The spectrally and spatially resolved HCN-to-HCO ⁺ flux ratios can provide additional information on the physical origin of the elevated flux ratios in nearby ULIRG nuclei compared to previously conducted spatially integrated and/or velocity-integrated analyses.

We present an analysis of the rest-frame optical JWST NIRSpec Fixed Slit spectra of extended host galaxy emission in 12 moderate luminosity quasars from the Subaru High- z Exploration of Low-Luminosity Quasars sample at redshifts 6.0 < z < 6.4. We fit and subtract a point-spread model based on observations of a calibration star and use it to remove the quasar from the 2D spectra, leaving only extended emission, which we analyze. Ten of 12 systems show spatially extended line emission, and six of 12 systems show an extended stellar continuum. From the extended [O III ] λ 5008 emission line, we measure a 132 ± 22 km s ⁻¹ ionized outflow in one system and 52 ± 12 km s ⁻¹ rotation, suggesting a coherent disk, in another. From the extended narrow H α emission, which we hypothesize is ionized by star-forming regions rather than the quasar, we measure star formation rates ranging from ∼7 to 111 M _⊙ yr ⁻¹ , the majority of which are consistent with the star-forming main sequence (SFMS) at z ≈ 6. The positions of our host galaxies on the log 10 [ O III ] λ 5008 / H β versus log 10 [ NII ] 6584 / H α (R3N2) Baldwin–Phillips–Terlevich diagram indicate ionization rates typical of active galactic nucleus (AGN) activity in the low-redshift Universe, but are consistent with the placement of other z ≈ 6 quasar host galaxies, suggesting that the R3N2 line ratios cannot distinguish AGN- and star-formation-powered line emission at high redshifts. We conclude from the consistency between our quasar host sample with z ∼ 6 galaxies that the presence of a low-luminosity AGN causes little significant change in the properties of galaxies at z ≈ 6 on 10 Myr timescales.

High-z quasars are believed to reside in massive dark matter haloes (DMHs), suggesting that they reside in galaxy overdense regions. However, previous observations have shown a range of environments around them. These fields have been limited to luminous quasars (M1450 ≲ −25), for which photoevaporation may hinder galaxy formation in their vicinity. Here, we present Subaru/Hyper-Suprime Cam observations of the environments of four low-luminosity quasars (−24 < M1450 < −22) at z ∼ 6.18, which are expected to have a smaller photoevaporation effect. We detect Lyman α emitters (LAEs) with narrowband NB872 imaging, and measure the local LAE overdensity. One quasar (J0844−0132) resides in an overdense region (δLAE = 1.97 ± 0.40), whereas the other three fields are consistent with no overdensity. These results hold over the proximity zone of each quasar, suggesting that the diverse environment around quasars is independent of photoevaporation. We find no significant correlation between the LAE overdensities and the characteristics of host galaxies and supermassive black holes. Our quasars have host stellar mass measurements from JWST, allowing us to compare them with the LAE overdensity around galaxies without quasar activity with comparable stellar masses. We find that the LAE overdensity in the J0844−0132 field is stronger than that of galaxies with similar stellar mass at z ∼ 6.

During cosmic noon ( z ∼ 1–3), when both star formation and black hole growth peaked, galaxy mergers are predicted to trigger dual active galactic nuclei that eventually coalesce as supermassive black hole (SMBH) binaries. However, observations of dual quasars with sub-5 kpc separations—the critical phase preceding final coalescence—have remained challenging due to angular resolution limitations. We present the discovery and confirmation of two subarcsecond dual quasars at z > 1, selected from 59,025 Sloan Digital Sky Survey (SDSS) quasars, which fall within the footprint of the Hyper Suprime-Cam Survey. Using high-resolution Hubble Space Telescope imaging and slitless spectroscopy, we confirmed SDSS J1625+4309 ( z = 1.647, separation 0 . ″ 55/4.7 kpc) and SDSS J0229−0514 ( z = 3.174, separation 0 . ″ 42/3.2 kpc), probing the sub-5 kpc separation regime. Through the novel combination of WFC3/IR direct imaging (F140W) and grism spectroscopy (G141), we resolve both components morphologically and spectroscopically confirm their dual nature via detection of H β +[O iii ] and Mg ii emission lines in each nucleus. Two-dimensional image decomposition reveals distinct host galaxy morphologies: J1625+4309 shows an extended, disturbed structure ( R _e = 4.7 kpc) indicative of an ongoing major merger, while J0229−0514 exhibits a compact host ( R _e = 1.4 kpc) suggesting an advanced coalescence stage. Black hole mass estimates based on virial relations yield M BH ∼ 1 0 8.1 – 1 0 8.7 M ⊙ with line-of-sight velocity offsets of (0.7 ± 0.1) × 10 ³ km s ⁻¹ and (1.0 ± 0.2) × 10 ³ km s ⁻¹ , respectively. These confirmations directly constrain the frequency and properties of close dual quasars, opening new avenues for studying SMBH mergers at cosmic noon.