Examinando por Autor "Donnan, Fergus"

Mostrando 1 - 7 de 7

Acceso Abierto
GATOS – XI. Excess dust heating in the narrow-line regions of nearby AGN revealed with JWST/MIRI
(Blackwell Publishing, 2026-01-26) Haidar, Houda; Rosario, David J.; García Bernete, Ismael; Alonso-Herrero, Almudena; Audibert, Anelise; Campbell, Steph; Harrison, Chris; Costa, Tiago; Hermosa Muñoz, Laura; Combes, Francoise; Rigopoulou, Dimitra; Ricci, Claudio; Ramos Almeida, Cristina; Bellocchi, Enrica; Boorman, Peter; Bunker, Andrew; Davies, Richard; Delaney, Daniel; Díaz Santos, Tanio; Esposito, Federico; Fawcett, Victoria; Gandhi, Poshak; García-Burillo, Santiago; González Martín, Omaira; Hicks, Erin K. S.; Hönig, Sebastian; Labiano, Alvaro; Levenson, Nancy A.; Lopez-Rodriguez, Enrique; Packham, Christopher; Pereira Santaella, Miguel; Riffel, Rogemar A.; Rodríguez Ardila, Alberto; Schneider, John; Thomas Shimizu, Taro; Stalevski, Marko ; Villar Martín, Montserrat; Ward, Martin J.; Zhang, Lulu; Leeds, Gillian; Donnan, Fergus; European Commission (EC); Comunidad de Madrid; Ministerio de Ciencia e Innovación (MICINN); Swiss National Science Foundation (SNSF); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Ministry of Education, Science and Technological Development of the Republic of Serbia; Agencia Estatal de Investigación (AEI); European Research Council (ERC); UK Research and Innovation (UKRI); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Foundation of Rio Grande do Sul State for Research Support (FAPERGS)
We present James Webb Space Telescope/Mid-Infrared Instrument imaging of eight nearby active galactic nuclei (AGN) from the GATOS (Galactic Activity, Torus, and Outflow Survey) survey to investigate the physical conditions of extended dust in their narrow-line regions (NLRs). In four galaxies (ESO 428–G14, NGC 4388, NGC 3081, and NGC 5728), we detect spatially resolved dust structures extending ∼100–200 pc along the NLR. In these systems, we find a strong link between the morphology of the dust, the radio ejecta, and the coronal [Sivi] emission, implying that dust carries imprints of the processes shaping the NLR. Using spatially resolved spectral energy distributions, we show that dust in the NLR has systematically steeper slopes than star-forming clumps. This dust emits at temperatures in the range $150 \text{-} 220\, \rm K$, at a distance of ∼150 pc from the nucleus. Using simple models, we show that, even under optimistic assumptions of grain size and AGN luminosity, the excess mid-infrared emission cannot be explained by AGN illumination alone. We interpret this excess heating as in situ. We show that shocks with velocities v ∼ 200 - 400 km s in dense gas can close this gap, and in some cases even account for the total observed emission. This, combined with multiple lines of evidence for shocks in these regions, supports a scenario in which shocks not only coexist with dust but may be playing a key role in heating it. Our findings reveal shocks may be an important and previously overlooked driver of extended dust emission in the central hundreds of parsecs in AGN.
Acceso Abierto
GATOS: Distinct Feedback Modes in AGN Central Regions Revealed by Spatially Resolved JWST Spectroscopy
(IOP Publishing, 2026-08-20) Zhang, Lulu; Packham, Christopher; Hicks, Erin K. S.; García Bernete, Ismael; Alonso-Herrero, Almudena; Davies, R. I.; Ward, Martin J.; Delaney, Daniel; Izumi, Takuma; Rigopoulou, Dimitra; Ramos Almeida, Cristina; González Martín, Omaira; Riffel, Rogemar A.; Ricci, Claudio; Villar Martín, Montserrat; Combes, Francoise; Pereira Santaella, Miguel; Hönig, Sebastian; Bunker, Andrew; Boorman, Peter; Bellocchi, Enrica; Levenson, Nancy A.; García-Burillo, Santiago; Donnan, Fergus; Audibert, Anelise; Fuller, Lindsay; Díaz Santos, Tanio; Rosario, David J.; Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); Space Telescope Science Institute (STScI); Comunidad de Madrid; European Commission (EC); Universidad Nacional Autónoma de México (UNAM)
This Letter presents JWST MIRI/Medium-Resolution Spectrometer (MRS) observations of the central r ≈ 40–240 pc regions of five active galactic nuclei (AGN) spanning a wide range of luminosities (log Lbol/erg s−1 ≈ 39.8–43.8). Combining multiphase diagnostics from polycyclic aromatic hydrocarbons (PAHs), molecular hydrogen (H2), and ionized gas at spatial scales of ∼4–24 pc, this study presents a spatially resolved investigation into the effects of the two distinct AGN feedback modes—radiative and kinetic—on the surrounding medium. The results indicate that these two feedback modes, associated with AGN irradiation and shock processing, respectively, collectively drive the relative suppression of PAH emission in the nuclear regions of the targets studied here. Moreover, the coexistence of these two AGN feedback modes, especially the shock processing associated with either jets or outflows, in the central regions of AGN naturally explains both the bimodal distribution of PAH band ratios observed in the targets studied here and the seemingly disparate results reported in the literature. Although based on a limited sample, these findings provide new insights into calibrating star formation rates from PAH emission in AGN and, more importantly, lay the groundwork for a practical framework to diagnose and quantify AGN feedback in the JWST era.
Acceso Abierto
Kinematic detection of dusty outflows from active galactic nuclei: Polycyclic aromatic hydrocarbon kinematics of type 2 quasars with JWST/MIRI spectroscopy
(EDP Sciences, 2026-08-05) Donnan, Fergus; Ramos Almeida, Cristina; González Martín, Omaira; Sandstrom, Karin; Audibert, Anelise; Bianchin, Marina; Pereira Santaella, Miguel; García Bernete, Ismael; Universidad Nacional Autónoma de México (UNAM); Agencia Estatal de Investigación (AEI); Comunidad de Madrid
Context. Active galactic nuclei (AGN) are thought to have dusty outflows, but unlike in the gas phase, it is challenging to measure the kinematics of dust. Aims. We present the detection and analysis of the kinematics of dust in five type 2 quasars at z ~ 0.1 from the Quasar Feedback (QSOFEED) sample observed with JWST/MIRI spectroscopy. Methods. We used principal component analysis tomography to produce velocity maps of polycyclic aromatic hydrocarbon (PAH) features, which are the smallest carbonaceous dust particles. We were then able to compare velocity maps of the PAHs with emission lines of ionised and molecular gas. Results. We produced velocity maps of the 11.3 μm PAH feature, which traces large and neutral PAHs, for three out of the five objects, where all three show an outflow in the PAH kinematics. This becomes particularly clear after we subtracted disk kinematics, where the H2 rotational transitions also show residuals consistent with an outflow. Compared to previous work with Seyfert galaxies, this work suggests that dusty outflows are more common at higher Eddington ratios, λEdd ≳ 0.1, in agreement with previous suggestions, although the sample size is small. We were unable to produce velocity maps for the 6.2 μm PAH, which traces ionised PAHs, potentially due to differences in the intrinsic profile and/or suppression of the feature in AGN, which was seen previously in Seyfert galaxies. This reflects studies of PAH band ratios where AGN outflows have more neutral PAHs. Conclusions. This work demonstrates that dusty outflows may be common, particularly at high Eddington ratios, and it therefore plays a key role in the evolution and life cycle of AGN.
Acceso Abierto
Polycyclic aromatic hydrocarbon emission in galaxies as seen with JWST
(Royal Astronomical Society, 2024-08-01) Rigopoulou, Dimitra; Donnan, Fergus; García Bernete, Ismael; Pereira Santaella, Miguel; Alonso-Herrero, Almudena; Davies, Richard; Hunt, L. K.; Roche, P. F.; Shimizu, Thomas Taro; 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.
Acceso Abierto
The Galaxy Activity, Torus, and Outflow Survey (GATOS) V. Unveiling PAH survival and resilience in the circumnuclear regions of AGNs with JWST
(EDP Sciences, 2024-09-09) García Bernete, Ismael; Rigopoulou, Dimitra; Donnan, Fergus; Alonso-Herrero, Almudena; Pereira Santaella, Miguel; Shimizu, Thomas Taro; Davies, Richard; Roche, P. F.; García-Burillo, Santiago; Labiano, Alvaro; Hermosa Muñoz, Laura; Zhang, Lulu; Audibert, Anelise; Bellocchi, Enrica; Bunker, Andrew; Combes, Francoise; Delaney, Daniel; Esparza Arredondo, Donaji; Gandhi, P.; González Martín, Omaira; Hönig, Sebastian; Imanishi, Masatoshi; Hicks, Erin K. S.; Fuller, Lindsay; Leist, Mason Tanner; Levenson, Nancy A.; López Rodríguez, Enrique; Packham, Christopher; Ramos Almeida, Cristina; Ricci, Claudio; Stalevski, Marko; Villar Martín, Montserrat; Ward, Martin J.; Science and Technology Facilities Council (STFC); Comunidad de Madrid; European Commission (EC); European Space Agency (ESA); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Ministerio de Ciencia e Innovación (MICINN); National Aeronautics and Space Administration (NASA); Space Telescope Science Institute (STScI); Universidad Nacional Autónoma de México (UNAM)
This study analyses JWST MIRI/MRS observations of the infrared (IR) polycyclic aromatic hydrocarbon (PAH) bands in the nuclear (∼0.4″ at 11 μm; ∼75 pc) and circumnuclear regions (inner ∼kpc) of local active galactic nuclei (AGNs) from the Galactic Activity, Torus, and Outflow Survey (GATOS). We examine the PAH properties in the circumnuclear regions of AGNs and the projected direction of AGN-outflows and compare them to those in star-forming regions and the innermost regions of AGNs. This study employs 4.9–28.1 μm sub-arcsecond angular resolution data to investigate the properties of PAHs in three nearby sources (DL ∼ 30 − 40 Mpc). Our findings are aligned with previous JWST studies, demonstrating that the central regions of AGNs display a larger fraction of neutral PAH molecules (i.e. elevated 11.3/6.2 and 11.3/7.7 μm PAH ratios) in comparison to star-forming galaxies. We find that AGNs might affect not only the PAH population in the innermost region, but also in the extended regions up to ∼kpc scales. By comparing our observations to PAH diagnostic diagrams, we find that, in general, regions located in the projected direction of the AGN-outflow occupy similar positions on the PAH diagnostic diagrams as those of the innermost regions of AGNs. Star-forming regions that are not affected by the AGNs in these galaxies share the same part of the diagram as star-forming galaxies. We also examined the potential of the PAH-H2 diagram to disentangle AGN-versus-star-forming activity. Our results suggest that in Seyfert-like AGNs, the illumination and feedback from the AGN might affect the PAH population at nuclear and kpc scales, particularly with respect to the ionisation state of the PAH grains. However, PAH molecular sizes are rather similar. The carriers of the ionised PAH bands (6.2 and 7.7 μm) are less resilient than those of neutral PAH bands (11.3 μm), which might be particularly important for strongly AGN-host coupled systems. Therefore, caution must be applied when using PAH bands as star-formation rate indicators in these systems even at kpc scales, with the effects of the AGN being more important for ionised ones.
Acceso Abierto
The Galaxy Activity, Torus, and Outflow Survey (GATOS): III. Revealing the inner icy structure in local active galactic nuclei
(EDP Sciences, 2024-01-01) García Bernete, Ismael; Alonso-Herrero, Almudena; Rigopoulou, Dimitra; Pereira Santaella, Miguel; Shimizu, Thomas Taro; Davies, Richard; Donnan, Fergus; Roche, P. F.; González Martín, Omaira; Ramos Almeida, Cristina; Bellocchi, Enrica; Boorman, Peter; Combes, Francoise; Efstathiou, A.; Esparza Arredondo, Donaji; García-Burillo, Santiago; González Alfonso, E. ; Hicks, Erin K. S.; Hönig, Sebastian; Labiano, Alvaro; Levenson, Nancy A.; Lopez-Rodriguez, Enrique; Ricci, Claudio; Packham, Christopher; Rouan, Daniel; Stalevski, Marko; Ward, Martin J.; Ministerio de Ciencia e Innovación (MICINN); Science and Technology Facilities Council (STFC); Universidad Nacional Autónoma de México (UNAM); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)
We use JWST/MIRI MRS spectroscopy of a sample of six local obscured type 1.9/2 active galactic nuclei (AGN) to compare their nuclear mid-IR absorption bands with the level of nuclear obscuration traced by X-rays. This study is the first to use subarcsecond angular resolution data of local obscured AGN to investigate the nuclear mid-IR absorption bands with a wide wavelength coverage (4.9–28.1 μm). All the nuclei show the 9.7 μm silicate band in absorption. We compare the strength of the 9.7 and 18 μm silicate features with torus model predictions. The observed silicate features are generally well explained by clumpy and smooth torus models. We report the detection of the 6 μm dirty water ice band (i.e., a mix of water and other molecules such as CO and CO2) at subarcsecond scales (∼0.26″ at 6 μm; inner ∼50 pc) in a sample of local AGN with different levels of nuclear obscuration in the range log NHX-Ray (cm−2)∼22 − 25. We find good correlation between the 6 μm water ice optical depths and NHX-Ray. This result indicates that the water ice absorption might be a reliable tracer of the nuclear intrinsic obscuration in AGN. The weak water ice absorption in less obscured AGN (log NHX-ray (cm−2)≲23.0 cm−2) might be related to the hotter dust temperature (> TsubH2O ∼ 110 K) expected to be reached in the outer layers of the torus due to their more inhomogeneous medium. Our results suggest it might be necessary to include the molecular content, such as H2O, aliphatic hydrocarbons (CH−), and more complex polycyclic aromatic hydrocarbon (PAH) molecules, in torus models to better constrain key parameters such as the torus covering factor (i.e., nuclear obscuration).
Acceso Abierto
The PAH 3.4 micron feature as a tracer of shielding in the Orion Bar and NGC 6240
(Royal Astronomical Society, 2025-11-18) Thatte, Niranjan; Rigopoulou, Dimitra; Donnan, Fergus; García Bernete, Ismael; Pereira Santaella, Miguel; Draine, B.; Veenema, Oscar; Kerkeni, Boutheïna; Alonso-Herrero, Almudena; Hermosa Muñoz, Laura; Speranza, G.; Science and Technology Facilities Council (STFC); Comunidad de Madrid; University of Oxford; Agencia Estatal de Investigación (España)
We have carried out a detailed analysis of the 3.4 μm spectral feature arising from Polycyclic Aromatic Hydrocarbons (PAH), using James Webb Space Telescope archival data. For the first time in an external galaxy (NGC 6240), we have identified two distinct spectral components of the PAH 3.4 μm feature: a shorter wavelength component at 3.395 μm, which we attribute to short aliphatic chains tightly attached to the aromatic rings of the PAH molecules; and a longer wavelength feature at 3.405 μm that arises from longer, more fragile, aliphatic chains that are weakly attached to the parent PAH molecule. These longer chains are more easily destroyed by far-ultraviolet photons (>5 eV) and PAH thermal emission only occurs where PAH molecules are shielded from more energetic photons by dense molecular gas. We see a very strong correlation in the morphology of the PAH 3.395 μm feature with the PAH 3.3 μm emission, the latter arising from robust aromatic PAH molecules. We also see an equally strong correlation between the PAH 3.405 μm morphology and the warm molecular gas, as traced by H2 vibrational lines. We show that the flux ratio PAH 3.395/PAH 3.405 < 0.3 corresponds strongly to regions where the PAH molecules are shielded by dense molecular gas, so that only modestly energetic UV photons penetrate to excite the PAHs. Our work shows that PAH 3.405 μm and PAH 3.395 μm emission features can provide robust diagnostics of the physical conditions of the interstellar medium in external galaxies, and can be used to quantify the energies of the photon field penetrating molecular clouds.