The scatter ( sSFR) of the specific star formation rates of galaxies is a measure of the diversity in their star formation histories (SFHs) at a given mass. In this paper, we employ the Evolution and ...Assembly of GaLaxies and their Environments (EAGLE) simulations to study the dependence of the sSFR of galaxies on stellar mass (M ) through the sSFR-M relation in z ∼ 0-4. We find that the relation evolves with time, with the dispersion depending on both stellar mass and redshift. The models point to an evolving U-shaped form for the sSFR-M relation, with the scatter being minimal at a characteristic mass M of 109.5 M and increasing both at lower and higher masses. This implies that the diversity of SFHs increases toward both the low- and high-mass ends. We find that feedback from active galactic nuclei is important for increasing the sSFR for high-mass objects. On the other hand, we suggest that feedback from supernovae increases the sSFR of galaxies at the low-mass end. We also find that excluding galaxies that have experienced recent mergers does not significantly affect the sSFR-M relation. Furthermore, we employ the EAGLE simulations in combination with the radiative transfer code SKIRT to evaluate the effect of SFR/stellar mass diagnostics in the sSFR-M relation, and find that the SFR/M methodologies (e.g., SED fitting, UV+IR, UV+IRX-β) widely used in the literature to obtain intrinsic properties of galaxies have a large effect on the derived shape and normalization of the sSFR-M relation.
Polar dust has been discovered in a number of local Active Galactic Nuclei (AGN), with radiation-driven torus models predicting a wind to be its main driver. However, little is known about its ...characteristics, spatial extent, or connection to the larger scale outflows. We present the first JWST/MIRI study aimed at imaging polar dust by zooming onto the centre of ESO 428-G14, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS) survey of local AGN. We detect extended mid-infrared (MIR) emission within 200 pc from the nucleus. This polar structure is co-linear with a radio jet and lies perpendicular to a molecular gas lane that feeds and obscures the nucleus. Its morphology bears a striking resemblance to that of gas ionised by the AGN in the narrow-line region. We demonstrate that part of this spatial correspondence is due to contamination within the JWST filter bands from strong emission lines. Correcting for the contamination, we find the morphology of the dust continuum to be more compact, though still clearly extended out to ~ 100 pc. We estimate the emitting dust has a temperature of ~ 120 K. Using simple models, we find that the heating of small dust grains by the radiation from the central AGN and/or radiative jet-induced shocks is responsible for the extended MIR emission. Radiation-driven dusty winds from the torus is unlikely to be important. This has important implications for scales to which AGN winds can carry dust and dense gas out into their host galaxies.
The scatter (\({\rm\sigma_{\text{sSFR}}}\)) of the specific star formation rates (sSFRs) of galaxies is a measure of the diversity in their star formation histories (SFHs) at a given mass. In this ...paper we employ the EAGLE simulations to study the dependence of the \({\rm \sigma_{\text{sSFR}}}\) of galaxies on stellar mass (\({\rm M_{\star}}\)) through the \({\rm \sigma_{\text{sSFR}}}\)-\({\rm M_{\star}}\) relation in \( {\rm z \sim 0-4}\). We find that the relation evolves with time, with the dispersion depending on both stellar mass and redshift. The models point to an evolving U-shape form for the \({\rm \sigma_{\text{sSFR}}}\)-\({\rm M_{\star}}\) relation with the scatter being minimal at a characteristic mass \(M^{\star}\) of \({\rm 10^{9.5}}\) \({\rm M_{\odot}}\) and increasing both at lower and higher masses. This implication is that the diversity of SFHs increases towards both at the low- and high-mass ends. We find that active galactic nuclei feedback is important for increasing the \({\rm \sigma_{\text{sSFR}}}\) for high mass objects. On the other hand, we suggest that SNe feedback increases the \({\rm \sigma_{\text{sSFR}}}\) of galaxies at the low-mass end. We also find that excluding galaxies that have experienced recent mergers does not significantly affect the \({\rm \sigma_{\text{sSFR}}}\)-\({\rm M_{\star}}\) relation. Furthermore, we employ the combination of the EAGLE simulations with the radiative transfer code SKIRT to evaluate the effect of SFR/stellar mass diagnostics in the \({\rm \sigma_{\text{sSFR}}}\)-\({\rm M_{\star}}\) relation and find that the \({\rm SFR/M_{\star}}\) methodologies (e.g. SED fitting, UV+IR, UV+IRX-\(\beta\)) widely used in the literature to obtain intrinsic properties of galaxies have a large effect on the derived shape and normalization of the \({\rm \sigma_{\text{sSFR}}}\)-\({\rm M_{\star}}\) relation.
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