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- Fomalont, E. B., et al.
(författare)
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THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
- 2015
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 808:1
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Tidskriftsartikel (refereegranskat)abstract
- A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.
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| 4. |
- Hattori, T, et al.
(författare)
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Administration of umbilical cord blood cells transiently decreased hypoxic-ischemic brain injury in neonatal rats
- 2015
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Ingår i: Developmental neuroscience. - : S. Karger AG. - 1421-9859 .- 0378-5866. ; 37:2, s. 95-104
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate whether the administration of mononuclear cells derived from human umbilical cord blood cells (UCBCs) could ameliorate hypoxic-ischemic brain injury in a neonatal rat model. The left carotid arteries of 7-day-old rats were ligated, and the rats were then exposed to 8% oxygen for 60 min. Mononuclear cells derived from UCBCs using the Ficoll-Hypaque technique were injected intraperitoneally 6 h after the insult (1.0 × 10<sup>7</sup> cells). Twenty-four hours after the insult, the number of cells positive for the oxidative stress markers 4-hydroxy-2-nonenal and nitrotyrosine, in the dentate gyrus of the hippocampus in the UCBC-treated group, decreased by 36 and 42%, respectively, compared with those in the control group. In addition, the number of cells positive for the apoptosis markers active caspase-3 and apoptosis-inducing factor decreased by 53 and 58%, respectively. The number of activated microglia (ED1-positive cells) was 51% lower in the UCBC group compared with the control group. In a gait analysis performed 2 weeks after the insult, there were no significant differences among the sham-operated, control and UCBC groups. An active avoidance test using a shuttle box the following week also revealed no significant differences among the groups. Neither the volumes of the hippocampi, corpus callosum and cortices nor the numbers of neurons in the hippocampus were different between the UCBC and control groups. In summary, a single intraperitoneal injection of UCBC-derived mononuclear cells 6 h after an ischemic insult was associated with a transient reduction in numbers of apoptosis and oxidative stress marker-positive cells, but it did not induce long-term morphological or functional protection. Repeated administration or a combination treatment may be required to achieve sustained protection.
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- Izumi, T., et al.
(författare)
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ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469
- 2015
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 811:1, s. Article Number: 39-
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Tidskriftsartikel (refereegranskat)abstract
- We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type. 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.'' 5x0.'' 4 = 165 x 132 pc) at submillimeter wavelengths. Utilizing the wide. bandwidth of ALMA, we simultaneously obtained HCN(4-3), HCO+(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860 mu m continuum. The region consists of the central similar to 1 '' component and the surrounding starburst ring with a radius of similar to 1.'' 5-2.'' 5. Several structures connect these components. Except for CO(3-2), these dense gas tracers are significantly concentrated toward the central similar to 1 '', suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4-3)/HCO+(4-3) and HCN(4-3)/CS(7-6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4-3)/HCO+(4-3) ratio at the AGN position of NGC 7469 (1.11 +/- 0.06) is almost half of the corresponding value of the low-luminosity type. 1 Seyfert galaxy NGC 1097 (2.0 +/- 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (similar to 1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097.
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| 6. |
- Izumi, T., et al.
(författare)
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On the Disappearance of a Cold Molecular Torus around the Low-luminosity Active Galactic Nucleus of NGC 1097
- 2017
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 845:1, s. L5-
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Tidskriftsartikel (refereegranskat)abstract
- We used the Atacama Large Millimeter/Submillimeter Array to map the CO(3-2) and the underlying continuum emissions around the type-1low-luminosity active galactic nucleus (LLAGN; bolometric luminosity less than or similar to 10(42) erg. s(-1)) of NGC 1097 at similar to 10 pc resolution. These observations revealed a detailed cold gas distribution within a similar to 100 pc of this LLAGN. In contrast to the luminous Seyfert galaxy NGC 1068, where a similar to 7 pc cold molecular torus was recently revealed, a distinctively dense and compact torus is missing in our CO(3-2) integrated intensity map of NGC 1097. Based on the CO(3-2) flux, the gas mass of the torus of NGC 1097 would be a factor of greater than or similar to 2-3 less than that found for NGC 1068 by using the same CO-to-H-2 conversion factor, which implies less active nuclear star formation and/or inflows in NGC 1097. Our dynamical modeling of the CO(3-2) velocity field implies that the cold molecular gas is concentrated in a thin layer as compared to the hot gas traced by the 2.12 mu m H-2 emission in and around the torus. Furthermore, we suggest that NGC 1097 hosts a geometrically thinner torus than NGC 1068. Although the physical origin of the torus thickness remains unclear, our observations support a theoretical prediction that geometrically thick tori with high opacity will become deficient as AGNs evolve from luminous Seyferts to LLAGNs.
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