Examinando por Autor "Shimizu, T."

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Acceso Abierto
Molecular gas stratification and disturbed kinematics in the Seyfert galaxy MCG-05-23-16 revealed by JWST and ALMA
(EDP Sciences, 2025-01-15) Esparza Arredondo, D., S.; Ramos Almeida, Cristina; Audibert, A.; Pereira Santaella, Miguel; García Bernete, I.; García-Burillo, Santiago, S.; Shimizu, T.; Davies, R.; Hermosa Muñoz, Laura; Alonso-Herrero, Almudena; Combes, Francoise; Speranza, G.; Zhang, Lulu; Campbell, Stephanie; Bellocchi, Enrica; Bunker, Andrew J.; Díaz Santos, T.; García Lorenzo, B.; González Martín, O.; Hicks, Erin K. S.; Labiano, Alvaro; Levenson, Nancy A.; Ricci, C.; Rosario, D.; Hönig, Sebastian; Packham, Christopher, C.; Stalevski, Marko; Fuller, L.; Izumi, T.; López Rodríguez, Enrique, E.; Rigopoulou, Dimitra; Rouan, D.; Ward, Martin; European Research Council (ERC); Comunidad de Madrid; Agencia Estatal de Investigación (España); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Space Telescope Science Institute (US); Hellenic Foundation for Research and Innovation; Agencia Nacional de Investigación y Desarrollo (Chile)
Understanding the processes that drive the morphology and kinematics of molecular gas in galaxies is crucial for comprehending star formation and, ultimately, galaxy evolution. Using data from the Galactic Activity, Torus and Outflow Survey (GATOS) obtained with the James Webb Space Telescope (JWST) and the archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), we study the behavior of the warm molecular gas at temperatures of hundreds of Kelvin and the cold molecular gas at tens of Kelvin in the galaxy MCG−05−23−16, which hosts an active galactic nucleus (AGN). Hubble Space Telescope (HST) images of this spheroidal galaxy, classified in the optical as S0, show a dust lane resembling a nuclear spiral and a surrounding ring. These features are also detected in CO(2−1) and H2, and their morphologies and kinematics are consistent with rotation plus local inward gas motions along the kinematic minor axis in the presence of a nuclear bar. The H2 transitions 0-0 S(3), 0-0 S(4), and 0-0 S(5), which trace warmer and more excited gas, show more disrupted kinematics than 0-0 S(1) and 0-0 S(2), including clumps of high velocity dispersion (of up to ∼160 km s−1), in regions devoid of CO(2−1). The kinematics of one of these clumps, located ∼350 pc westward of the nucleus, are consistent with outflowing gas, possibly driven by localized star formation traced by polycyclic aromatic hydrocarbon emission at 11.3 μm. Overall, we observe a stratification of the molecular gas, with the colder gas located in the nuclear spiral, ring, and connecting arms, and most of the warmer gas with a higher velocity dispersion filling the inter-arm space. The compact jet, approximately 200 pc in size, detected with Very Large Array (VLA) observations, does not appear to significantly affect the distribution and kinematics of the molecular gas, possibly due to its limited intersection with the molecular gas disk.
Acceso Abierto
Polycyclic aromatic hydrocarbon emission in galaxies as seen with JWST
(Royal Astronomical Society, 2024-08-01) Rigopoulou, Dimitra; Donnan, Fergus; García-Bernete, I.; Pereira Santaella, Miguel; Alonso-Herrero, Almudena; Davies, R.; Hunt, L. K.; Roche, P. F.; Shimizu, T.; Ministerio de Ciencia e Innovación (MICINN); Science and Technology Facilities Council (STFC)
We present a systematic study of mid-infrared spectra of galaxies including star-forming galaxies and active galactic nuclei observed with JWST MIRI-MRS and NIRSpec-IFU. We focus on the relative variations of the 3.3, 6.2, 7.7, 11.3, 12.7, and 17 m polycyclic aromatic hydrocarbon (PAH) features within spatially resolved regions of galaxies including NGC 3256, NGC 7469, VV 114, II Zw96, and NGC 5728. Using theoretical PAH models and extending our earlier work, we introduce a new PAH diagnostic involving the 17 m PAH feature. To determine the drivers of PAH band variations in galaxies, we compare observed PAH spectral bands to predictions from theoretical PAH models. We consider extinction, dehydrogenation, and PAH size and charge as possible drivers of PAH band variations. We find a surprising uniformity in PAH size distribution among the spatially resolved regions of the galaxies studied here, with no evidence for preferential destruction of the smallest grains, contrary to earlier findings. Neither extinction nor dehydrogenation play a crucial role in setting the observed PAH bands. Instead, we find that PAH charge plays a significant role in PAH inter-band variations. We find a tight relation between PAH charge and the intensity of the radiation field as traced by the [Ne iii][Ne ii] maps. In agreement with recent JWST results, we find a predominance of neutral PAH molecules in the nuclei of active galaxies and their outflows. Ionized PAHs are the dominant population in star-forming galaxies. We discuss the implications of our findings for the use of PAHs as ISM tracers in high redshift galaxies.