| 1. |
|
|
| 2. |
- Lamperti, I., et al.
(författare)
-
SUPER: V. ALMA continuum observations of z ∼2 AGN and the elusive evidence of outflows influencing star formation
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 654
-
Tidskriftsartikel (refereegranskat)abstract
- We study the impact of active galactic nuclei (AGN) ionised outflows on star formation in high-redshift AGN host galaxies, by combining near-infrared integral field spectroscopic (IFS) observations, mapping the H emission and [O iii]5007 outflows, with matched-resolution observations of the rest-frame far-infrared (FIR) emission.We present high-resolution ALMA Band 7 observations of eight X-ray selected AGN (L2-10 keV = 1043:81045:2 erg s1) at z 2 from the SUPER (SINFONI Survey for Unveiling the Physics and Eect of Radiative feedback) sample, targeting the observed-frame 870 m (rest-frame 260 m) continuum at 2 kpc (0.200) spatial resolution. The targets were selected among the SUPER AGN with an [O iii] detection in the IFS maps and with a detection in the FIR photometry. We detected six out of eight targets with signal-to-noise ratio S=N & 10 in the ALMA maps, from which we measured continuum flux densities in the range 0:272:58 mJy and FIR half-light radii (Re) in the range 0:8-2:1 kpc. The other two targets were detected with S/N of 3.6 and 5.9, which are insucient for spatially resolved analysis. The FIR Re of our sample are comparable to other AGN and star-forming galaxies at a similar redshift from the literature. However, combining our sample with the literature samples, we find that the mean FIR size in X-ray AGN (Re = 1:16 0:11 kpc) is slightly smaller than in non-AGN (Re = 1:69 0:13 kpc). From spectral energy distribution fitting, we find that the main contribution to the 260 m flux density is dust heated by star formation, with 4% contribution from AGN-heated dust and 1% from synchrotron emission. The majority of our sample show dierent morphologies for the FIR (mostly due to reprocessed stellar emission) and the ionised gas emission (H and [O iii], mostly due to AGN emission). This could be due to the dierent locations of dust and ionised gas, the dierent sources of the emission (stars and AGN), or the eect of dust obscuration.We are unable to identify any residual H emission, above that dominated by AGN, that could be attributed to star formation. Under the assumption that the FIR emission is a reliable tracer of obscured star formation, we find that the obscured star formation activity in these AGN host galaxies is not clearly aected by the ionised outflows. However, we cannot rule out that star formation suppression is happening on smaller spatial scales than the ones we probe with our observations (<2 kpc) or on dierent timescales.
|
|
| 3. |
- Pereira-Santaella, M., et al.
(författare)
-
Physics of ULIRGs with MUSE and ALMA: The PUMA project: II. Are local ULIRGs powered by AGN: The subkiloparsec view of the 220 GHz continuum
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 651
-
Tidskriftsartikel (refereegranskat)abstract
- We analyze new high-resolution (400 pc) ∼220 GHz continuum and CO(2-1) Atacama Large Millimeter Array (ALMA) observations of a representative sample of 23 local (z < 0.165) ultra-luminous infrared systems (ULIRGs; 34 individual nuclei) as part of the "Physics of ULIRGs with MUSE and ALMA"(PUMA) project. The deconvolved half-light radii of the ∼220 GHz continuum sources, rcont, are between < 60 pc and 350 pc (median 80-100 pc). We associate these regions with the regions emitting the bulk of the infrared luminosity (LIR). The good agreement, within a factor of 2, between the observed ∼220 GHz fluxes and the extrapolation of the infrared gray-body as well as the small contributions from synchrotron and free-free emission support this assumption. The cold molecular gas emission sizes, rCO, are between 60 and 700 pc and are similar in advanced mergers and early interacting systems. On average, rCO are ∼2.5 times larger than rcont. Using these measurements, we derived the nuclear LIR and cold molecular gas surface densities (ςLIR = 1011.5-1014.3 L· kpc-2 and ςH2 = 102.9-104.2 M· pc-2, respectively). Assuming that the LIR is produced by star formation, the median ςLIR corresponds to ςSFR = 2500 M· yr-1 kpc-2. This ςSFR implies extremely short depletion times, ςH2/ςSFR < 1-15 Myr, and unphysical star formation efficiencies > 1 for 70% of the sample. Therefore, this favors the presence of an obscured active galactic nucleus (AGN) in these objects that could dominate the LIR. We also classify the ULIRG nuclei in two groups: (a) compact nuclei (rcont < 120 pc) with high mid-infrared excess emission (ΔL6-20 μm/LIR) found in optically classified AGN; and (b) nuclei following a relation with decreasing ΔL6-20 μm/LIR for decreasing rcont. The majority, 60%, of the nuclei in interacting systems lie in the low-rcont end (<120 pc) of this relation, while this is the case for only 30% of the mergers. This suggests that in the early stages of the interaction, the activity occurs in a very compact and dust-obscured region while, in more advanced merger stages, the activity is more extended, unless an optically detected AGN is present. Approximately two-thirds of the nuclei have nuclear radiation pressures above the Eddington limit. This is consistent with the ubiquitous detection of massive outflows in local ULIRGs and supports the importance of the radiation pressure in the outflow launching process.
|
|
| 4. |
- Young, D., et al.
(författare)
-
The A2b adenosine receptor protects against inflammation and excessive vascular adhesion
- 2006
-
Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 116:7, s. 1913-1923
-
Tidskriftsartikel (refereegranskat)abstract
- Adenosine has been described as playing a role in the control of inflammation, but it has not been certain which of its receptors mediate this effect. Here, we generated an A2B adenosine receptor-knockout/reporter gene-knock-in (A2BAR-knockout/reporter gene-knock-in) mouse model and showed receptor gene expression in the vasculature and macrophages, the ablation of which causes low-grade inflammation compared with age-, sex-, and strain-matched control mice. Augmentation of proinflammatory cytokines, such as TNF-alpha, and a consequent downregulation of IkappaB-alpha are the underlying mechanisms for an observed upregulation of adhesion molecules in the vasculature of these A2BAR-null mice. Intriguingly, leukocyte adhesion to the vasculature is significantly increased in the A2BAR-knockout mice. Exposure to an endotoxin results in augmented proinflammatory cytokine levels in A2BAR-null mice compared with control mice. Bone marrow transplantations indicated that bone marrow (and to a lesser extent vascular) A2BARs regulate these processes. Hence, we identify the A2BAR as a new critical regulator of inflammation and vascular adhesion primarily via signals from hematopoietic cells to the vasculature, focusing attention on the receptor as a therapeutic target
|
|
