| 1. |
- De La Fuente, Eduardo, et al.
(författare)
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Detection of a new molecular cloud in the LHAASO J2108+5157 region supporting a hadronic PeVatron scenario
- 2023
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Ingår i: Publication of the Astronomical Society of Japan. - 2053-051X .- 0004-6264. ; 75:3, s. 546-566
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Tidskriftsartikel (refereegranskat)abstract
- PeVatrons are the most powerful naturally occurring particle accelerators in the Universe. The identification of counterparts associated to astrophysical objects such as dying massive stars, molecular gas, star-forming regions, and star clusters is essential to clarify the underlying nature of the PeV emission, i.e., hadronic or leptonic. We present 12,13CO (J = 2→1) observations made with the 1.85 m radio-Telescope of the Osaka Prefecture University toward the Cygnus OB7 molecular cloud, which contains the PeVatron candidate LHAASO J2108+5157. We investigate the nature of the sub-PeV (gamma-ray) emission by studying the nucleon density determined from the content of H i and H2, derived from the CO observations. In addition to MML[2017]4607, detected via the observations of the optically thick 12CO (J = 1→0) emission, we infer the presence of an optically thin molecular cloud, named [FKT-MC]2022, whose angular size is 1-1 ± 0.}^\circ}}2. We propose this cloud as a new candidate to produce the sub-PeV emission observed in LHAASO J2108+5157. Considering a distance of 1.7 kpc, we estimate a nucleon (H i + H2) density of 37 ± 14 cm-3, and a total nucleon mass(H i + H2) of 1.5 ± 0.6 × 104 M·. On the other hand, we confirm that Kronberger 82 is a molecular clump with an angular size of 0°1, a nucleon density ∼103 cm-3, and a mass ∼103 M·. Although Kronberger 82 hosts the physical conditions to produce the observed emission of LHAASO J2108+5157, [FKT-MC]2022 is located closer to it, suggesting that the latter could be the one associated to the sub-PeV emission. Under this scenario, our results favour a hadronic origin for the emission.
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| 2. |
- De La Fuente, Eduardo, et al.
(författare)
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Evidence for a gamma-ray molecular target in the enigmatic PeVatron candidate LHAASO J2108+5157
- 2023
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 675
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Tidskriftsartikel (refereegranskat)abstract
- Context . Peta-eV (PeV) astronomy emerged in 2021 with the discovery of ultra-high-energy gamma-ray sources associated with powerful natural particle accelerators known as PeVatrons. In order to determine the nature of their emission, namely whether it has a hadronic or leptonic origin, it is essential to characterise the physical parameters of the environment where it originates. Aims . We unambiguously confirm the association of molecular gas with the PeVatron candidate LHAASO J2108+5157 using unprecedented high angular-resolution (17′) 12,13CO(J = 1 → 0) observations carried out with the Nobeyama 45m radio telescope. Methods . We characterised a molecular cloud in the vicinity of the PeVatron candidate LHAASO J2108+5157 by determining its physical parameters from our 12,13CO(J = 1 → 0) line observations. We used an updated estimation of the distance to the cloud, which provided a more reliable result. The molecular emission was compared with excess gamma-ray images obtained with Fermi-LAT at energies above 2 GeV to search for spatial correlations and test a possible hadronic (π0 decay) origin for the gamma-ray emission. Results . We find that the morphology of the spatial distribution of the CO emission is strikingly similar to that of the Fermi-LAT excess gamma ray. By combining our observations with archival 21 cm HI line data, the nucleons (HI + H2) number density of the target molecular cloud is found to be 133.0 ± 45.0 cm-3, for the measured angular size of 0.55 ± 0.02 at a distance of 1.6 ± 0.1 kpc. The resulting total mass of the cloud is M(HI + H2) = 7.5±2.9×103M⊙. Under a hadronic scenario, we obtain a total energy of protons of Wp = 4.3 ± 1.5 × 1046 erg with a cutoff of 700±300 TeV, which reproduces the sub-PeV gamma-ray emission. Conclusions . We identified a molecular cloud in the vicinity of LHAASO J2107+5157 as the main target where cosmic rays from an unknown PeVatron produce the observed gamma-ray emission via π0 decay.
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| 3. |
- de la Fuente, Eduardo, et al.
(författare)
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Ultracompact H II regions with extended emission: the case of G43.89-0.78 and its molecular environment
- 2020
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 497:4, s. 4436-4447
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Tidskriftsartikel (refereegranskat)abstract
- The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory (OVRO), Atacama Large Millimetric Array (ALMA), and the infrared Spitzer observatories are powerful facilities to study massive star formation regions and related objects such as ultra-compact (UC) H II regions, molecular clumps, and cores. We used these telescopes to study the UC H II region G43.89-0.78. The morphological study at arcminute scales using NVSS and Spitzer data shows that this region is similar to those observed in the bubble-like structures revealed by Spitzer observations. With this result, and including a physical characterization based on 3.6 cm data, we suggest G43.89-0.78 be classified as an UC H II region with Extended Emission because it meets the operational definition given in this paper comparing radio continuum data at 3.6 and 20 cm. For the ultra-compact component, we use VLA data to obtain physical parameters at 3.6 cm confirming this region as an UC H II region. Using ALMA observations, we detect the presence of a dense (2.6 x 10(7) cm(-3)) and small (similar to 2.0 arcsec; 0.08 pc) molecular clump with a mass of 220 M-circle dot and average kinetic temperature of 21 K, located near to the UC H II region. In this clump, catalogued as G43.890-0.784, water masers also exist, possibly tracing a bipolar outflow. We discover in this vicinity two additional clumps which we label as G43.899-0.786 (T-d = 50 K; M = 11 M-circle dot) and G43.888-0.787 (T-d = 50 K; M = 15 M-circle dot).
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| 4. |
- Nishi, Stephanie K., et al.
(författare)
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Mediterranean, DASH, and MIND Dietary Patterns and Cognitive Function : The 2-Year Longitudinal Changes in an Older Spanish Cohort
- 2021
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media SA. - 1663-4365. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: Plant-forward dietary patterns have been associated with cardiometabolic health benefits, which, in turn, have been related to cognitive performance with inconsistent findings. The objective of this study was to examine the relationship between baseline adherence to three a priori dietary patterns (Mediterranean, DASH, and MIND diets) with 2-year changes in cognitive performance in older adults with overweight or obesity and high cardiovascular disease risk. Methods: A prospective cohort analysis was conducted within the PREDIMED-Plus trial, involving 6,647 men and women aged 55–75 years with overweight or obesity and metabolic syndrome. Using a validated, semiquantitative 143-item food frequency questionnaire completed at baseline, the dietary pattern adherence scores were calculated. An extensive neuropsychological test battery was administered at baseline and 2-year follow-up. Multivariable-adjusted linear regression models were used to assess associations between 2-year changes in cognitive function z-scores across tertiles of baseline adherence to the a priori dietary patterns. Results: Adherence to the Mediterranean diet at baseline was associated with 2-year changes in the general cognitive screening Mini-Mental State Examination (MMSE, β: 0.070; 95% CI: 0.014, 0.175, P-trend = 0.011), and two executive function-related assessments: the Trail Making Tests Part A (TMT-A, β: −0.054; 95% CI: −0.110, − 0.002, P-trend = 0.047) and Part B (TMT-B, β: −0.079; 95% CI: −0.134, −0.024, P-trend = 0.004). Adherence to the MIND diet was associated with the backward recall Digit Span Test assessment of working memory (DST-B, β: 0.058; 95% CI: 0.002, 0.114, P-trend = 0.045). However, higher adherence to the DASH dietary pattern was not associated with better cognitive function over a period of 2 years. Conclusion: In older Spanish individuals with overweight or obesity and at high cardiovascular disease risk, higher baseline adherence to the Mediterranean dietary pattern may be associated with better cognitive performance than lower adherence over a period of 2 years.
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| 5. |
- de la Fuente, Eduardo, et al.
(författare)
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The symbiotic and bipolar nebula M2-9: Morphological variability of the collimated ionized wind arising from the core
- 2022
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Ingår i: Publication of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 2053-051X .- 0004-6264. ; 74:3, s. 594-601
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Tidskriftsartikel (refereegranskat)abstract
- We studied the central region of bipolar nebula M 2-9 using radio-continuum observations obtained from the Jansky Very Large Array (JVLA) and the Atacama Large Millimeter Array (ALMA) interferometers. This work presents new images at similar to 43 GHz (similar to 7.0 mm) and similar to 345 GHz (similar to 0.9 mm) with angular resolutions of similar to 0 ''.047 and 0 ''.09, respectively. The continuum emission at similar to 43 GHz shows an elongated jet-like structure perpendicular to the similar to 345 GHz observation. We conclude that both emissions could correspond to tracing an isothermal collimated fast wind with constant expansion velocity and being driven by the circumstellar ring traced by ALMA. Although this configuration has been discussed within the scope of planetary nebulae models, there is a remarkable fact: the collimated fast wind shows morphological spatial variability. This supports the idea of a symbiotic binary system within the innermost part of M 2-9, which would be composed of a white dwarf and an AGB star. The latter could explain the mirror symmetry observed at larger scales due to their orbital motion.
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| 6. |
- De La Fuente, Eduardo, et al.
(författare)
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Ultracompact HII regions with extended emission: The complete view
- 2020
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 492:1, s. 895-914
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 The Author(s). In this paper, we present the results of a morphological study performed on a sample of 28 ultracompact HII (UC HII) regions located near extended free-free emission, using radio continuum (RC) observations at 3.6 cm with the C and D Very Large Array (VLA) configurations, with the aim of determining a direct connection between them. By using previously published observations in B and D VLA configurations, we compiled a final catalogue of 21 UC HII regions directly connected with the surrounding extended emission (EE). The observed morphology of most of the UC HII regions in RC emission is irregular (single- or multipeaked sources) and resembles a classical bubble structure in the Galactic plane with well-defined cometary arcs. RC images superimposed on colour composite Spitzer images reinforce the assignations of direct connection by the spatial coincidence between the UC components and regions of saturated 24 μm emission. We also find that the presence of EE may be crucial to understand the observed infrared excess because an underestimation of ionizing Lyman photons was considered in previous works (e.g. Wood & Churchwell; Kurtz, Churchwell & Wood).
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| 7. |
- Toledano-Juárez, Iván, et al.
(författare)
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Collision of molecular outflows in the L1448-C system
- 2023
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Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 522:1, s. 1591-1600
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of the central zone of the star-forming region L1448 at 217-230 GHz (∼1.3 mm) using Atacama Large Millimeter Array observations. Our study focuses on the detection of proto-stellar molecular outflows and the interaction with the surrounding medium towards sources L1448-C(N) and L1448-C(S). Both sources exhibit continuum emission, with L1448-C(N) being the brightest one. Based on its spectral index and the associated bipolar outflow, the continuum emission is the most likely to be associated with a circumstellar disk. The 12CO(J = 2→1) and SiO(J = 5→4) emissions associated with L1448-C(N) trace a bipolar outflow and a jet oriented along the northwest-southeast direction. The 12CO(J = 2→1) outflow for L1448-C(N) has a wide-open angle and a V-shape morphology. The SiO jet is highly collimated and has an axial extent comparable with the 12CO(J = 2→1) emission. There is not SiO(J = 5→4) emission towards L1448-C(S), but there is 12CO(J = 2→1) emission. The observations revealed that the red-shifted lobes of the 12CO(J = 2→1) outflows of L1448-C(N) and L1448-C(S) are colliding. As a result of this interaction, the L1448-C(S) lobe seems to be truncated. The collision of the molecular outflows is also hinted by the SiO(J = 5→4) emission, where the velocity dispersion increases significantly in the interaction zone. We also investigated whether it could be possible that this collision triggers the formation of new stars in the L1448-C system.
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