| 1. |
- Baum, Sebastian, et al.
(author)
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Paleodetectors for Galactic supernova neutrinos
- 2020
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In: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 101:10
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Journal article (peer-reviewed)abstract
- Paleodetectors are a proposed experimental technique in which one would search for traces of recoiling nuclei in ancient minerals. Natural minerals on Earth are as old as O(1) Gyr and, in many minerals, the damage tracks left by recoiling nuclei are also preserved for timescales long compared to 1 Gyr once created. Thus, even reading out relatively small target samples of order 100 g, paleodetectors would allow one to search for very rare events thanks to the large exposure, epsilon similar to 100 g Gyr = 10(5) t yr. Here, we explore the potential of paleodetectors to measure nuclear recoils induced by neutrinos from Galactic core collapse supernovae. We find that they would not only allow for a direct measurement of the average core collapse supernova rate in the Milky Way, but would also contain information about the time dependence of the local supernova rate over the past similar to 1 Gyr. Since the supernova rate is thought to be directly proportional to the star formation rate, such a measurement would provide a determination of the local star formation history. We investigate the sensitivity of paleodetectors to both a smooth time evolution and an enhancement of the core collapse supernova rate on relatively short timescales, as would be expected for a starburst period in the local group.
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| 2. |
- Beuther, H., et al.
(author)
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JWST Observations of Young protoStars (JOYS): Outflows and accretion in the high-mass star-forming region IRAS 23385+6053
- 2023
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 673
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Journal article (peer-reviewed)abstract
- Context. Understanding the earliest stages of star formation, and setting it in the context of the general cycle of matter in the interstellar medium, is a central aspect of research with the James Webb Space Telescope (JWST). Aims. The JWST program JOYS (JWST Observations of Young protoStars) aims to characterize the physical and chemical properties of young high- and low-mass star-forming regions, in particular the unique mid-infrared diagnostics of the warmer gas and solid-state components. We present early results from the high-mass star formation region IRAS 23385+6053. Methods. The JOYS program uses the Mid-Infrared Instrument (MIRI) Medium Resolution Spectrometer (MRS) with its integral field unit (IFU) to investigate a sample of high- and low-mass star-forming protostellar systems. Results. The full 5-? 28 μm MIRI MRS spectrum of IRAS 23385+6053 shows a plethora of interesting features. While the general spectrum is typical for an embedded protostar, we see many atomic and molecular gas lines boosted by the higher spectral resolution and sensitivity compared to previous space missions. Furthermore, ice and dust absorption features are also present. Here, we focus on the continuum emission, outflow tracers such as the H2(0-? 0)S(7), [FeII](4F9/2-6D9/2), and [NeII](2P1/2-2P3/2) lines, and the potential accretion tracer Humphreys α H I(7-6). The short-wavelength MIRI data resolve two continuum sources, A and B; mid-infrared source A is associated with the main millimeter continuum peak. The combination of mid-infrared and millimeter data reveals a young cluster in the making. Combining the mid-infrared outflow tracers H2, [FeII], and [NeII] with millimeter SiO data reveals a complex interplay of at least three molecular outflows driven by protostars in the forming cluster. Furthermore, the Humphreys α line is detected at a 3-?4σ? level toward the mid-infrared sources A and B. One can roughly estimate both accretion luminosities and corresponding accretion rates to be between ∼2.6 × 10-6 and ∼0.9 × 10-4 Mo yr-1. This is discussed in the context of the observed outflow rates. Conclusions. The analysis of the MIRI MRS observations for this young high-mass star-forming region reveals connected outflow and accretion signatures, as well as the enormous potential of JWST to boost our understanding of the physical and chemical processes at play during star formation.
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| 3. |
- Edwards, Thomas D. P., et al.
(author)
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Digging for dark matter : Spectral analysis and discovery potential of paleo-detectors
- 2019
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In: Physical Review D. Particles and fields. - : AMER PHYSICAL SOC. - 0556-2821 .- 1089-4918. ; 99:4
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Journal article (peer-reviewed)abstract
- Paleo-detectors are a recently proposed method for the direct detection of dark matter (DM). In such detectors, one would search for the persistent damage features left by DM–nucleus interactions in ancient minerals. Initial sensitivity projections have shown that paleo-detectors could probe much of the remaining weakly interacting massive particle (WIMP) parameter space. In this paper, we improve upon the cut-and-count approach previously used to estimate the sensitivity by performing a full spectral analysis of the background- and DM-induced signal spectra. We consider two scenarios for the systematic errors on the background spectra: (i) systematic errors on the normalization only, and (ii) systematic errors on the shape of the backgrounds. We find that the projected sensitivity is rather robust to imperfect knowledge of the backgrounds. Finally, we study how well the parameters of the true WIMP model could be reconstructed in the hypothetical case of a WIMP discovery.
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| 4. |
- Francis, L., et al.
(author)
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JOYS: MIRI/MRS spectroscopy of gas-phase molecules from the high-mass star-forming region IRAS 23385+6053
- 2024
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 683
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Journal article (peer-reviewed)abstract
- Context. Space-based mid-infrared (IR) spectroscopy is a powerful tool for the characterization of important star formation tracers of warm gas which are unobservable from the ground. The previous mid-IR spectra of bright high-mass protostars with the Infrared Space Observatory (ISO) in the hot-core phase typically show strong absorption features from molecules such as CO2, C2H2, and HCN. However, little is known about their fainter counterparts at earlier stages. Aims. We aim to characterize the gas-phase molecular features in James Webb Space Telescope Mid-Infrared Instrument Medium Resolution Spectrometer (MIRI/MRS) spectra of the young and clustered high-mass star-forming region IRAS 23385+6053. Methods. Spectra were extracted from several locations in the MIRI/MRS field of view, targeting two mid-IR sources tracing embedded massive protostars as well as three H2 bright outflow knots at distances of >8000 au from the multiple. Molecular features in the spectra were fit with local thermodynamic equilibrium (LTE) slab models, with their caveats discussed in detail. Results. Rich molecular spectra with emission from CO, H2, HD, H2O, C2H2, HCN, CO2, and OH are detected towards the two mid-IR sources. However, only CO and OH are seen towards the brightest H2 knot positions, suggesting that the majority of the observed species are associated with disks or hot core regions rather than outflows or shocks. The LTE model fits to 12CO2, C2H2, HCN emission suggest warm 120a-200 K emission arising from a disk surface around one or both protostars. The abundances of CO2 and C2H2 of ~10âà  à  7 are consistent with previous observations of high-mass protostars. Weak ~500 K H2O emission at ~6a-7 μm is detected towards one mid-IR source, whereas 250a-1050 K H2O absorption is found in the other. The H2O absorption may occur in the disk atmosphere due to strong accretion-heating of the midplane, or in a disk wind viewed at an ideal angle for absorption. CO emission may originate in the hot inner disk or outflow shocks, but NIRSpec data covering the 4.6 μm band head are required to determine the physical conditions of the CO gas, as the high temperatures seen in the MIRI data may be due to optical depth. OH emission is detected towards both mid-IR source positions and one of the shocks, and is likely excited by water photodissociation or chemical formation pumping in a highly non-LTE manner. Conclusions. The observed molecular spectra are consistent with disks having already formed around two protostars in the young IRAS 23385+6054 system. Molecular features mostly appear in emission from a variety of species, in contrast to the more evolved hot core phase protostars which typically show only absorption; however, further observations of young high-mass protostars are needed to disentangle geometry and viewing angle effects from evolution.
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| 5. |
- Gasman, Danny, et al.
(author)
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JWST MIRI/MRS in-flight absolute flux calibration and tailored fringe correction for unresolved sources
- 2023
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 673
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Journal article (peer-reviewed)abstract
- Context. The Medium Resolution Spectrometer (MRS) is one of the four observing modes of JWST/MIRI. Using JWST in-flight data of unresolved (point) sources, we can derive the MRS absolute spectral response function (ASRF) starting from raw data. Spectral fringing, caused by coherent reflections inside the detector arrays, plays a critical role in the derivation and interpretation of the MRS ASRF. The fringe corrections implemented in the current pipeline are not optimal for non-extended sources, and a high density of molecular features particularly inhibits an accurate correction. Aims. In this paper, we present an alternative way to calibrate the MIRI/MRS data. Firstly, we derive a fringe correction that accounts for the dependence of the fringe properties on the MIRI/MRS pupil illumination and detector pixel sampling of the point spread function. Secondly, we derive the MRS ASRF using an absolute flux calibrator observed across the full 5- 28 µm wavelength range of the MRS. Thirdly, we apply the new ASRF to the spectrum of a G dwarf and compare it with the output of the JWST/MIRI default data reduction pipeline. Finally, we examine the impact of the different fringe corrections on the detectability of molecular features in the G dwarf and K giant. Methods. The absolute flux calibrator HD 163466 (A-star) was used to derive tailored point source fringe flats at each of the default dither locations of the MRS. The fringe-corrected point source integrated spectrum of HD 163466 was used to derive the MRS ASRF using a theoretical model for the stellar continuum. A cross-correlation was run to quantify the uncertainty on the detection of CO, SiO, and OH in the K giant and CO in the G dwarf for different fringe corrections. Results. The point-source-tailored fringe correction and ASRF are found to perform at the same level as the current corrections, beating down the fringe contrast to the sub-percent level in the G dwarf in the longer wavelengths, whilst mitigating the alteration of real molecular features. The same tailored solutions can be applied to other MRS unresolved targets. Target acquisition is required to ensure the pointing is accurate enough to apply this method. A pointing repeatability issue in the MRS limits the effectiveness of the tailored fringe flats is at short wavelengths. Finally, resulting spectra require no scaling to make the sub-bands match, and a dichroic spectral leak at 12.2 µm is removed.
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| 6. |
- Gieser, C., et al.
(author)
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JOYS: Disentangling the warm and cold material in the high-mass IRAS 23385+6053 cluster
- 2023
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 679
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Journal article (peer-reviewed)abstract
- Context. High-mass star formation occurs in a clustered mode where fragmentation is observed from an early stage onward. Young protostars can now be studied in great detail with the recently launched James Webb Space Telescope (JWST). Aims. We study and compare the warm (>100 K) and cold (<100 K) material toward the high-mass star-forming region (HMSFR) IRAS 23385+6053 (IRAS 23385 hereafter) combining high-angular-resolution observations in the mid-infrared (MIR) with the JWST Observations of Young protoStars (JOYS) project and with the NOrthern Extended Millimeter Array (NOEMA) at millimeter (mm) wavelengths at angular resolutions of 0.a2 1.a0. Methods. We investigated the spatial morphology of atomic and molecular species using line-integrated intensity maps. We estimated the temperature and column density of different gas components using H2 transitions (warm and hot component) and a series of CH3CN transitions as well as 3 mm continuum emission (cold component). Results. Toward the central dense core of IRAS 23385, the material consists of relatively cold gas and dust ( 50 K), while multiple outflows create heated and/or shocked H2 and show enhanced temperatures ( 400 K) along the outflow structures. An energetic outflow with enhanced emission knots of [FeII] and [NiII] suggests J-type shocks, while two other outflows have enhanced emission of only H2 and [SI] caused by C-type shocks. The latter two outflows are also more prominent in molecular line emission at mm wavelengths (e.g., SiO, SO, H2CO, and CH3OH). Data of even higher angular resolution are needed to unambiguously identify the outflow-driving sources given the clustered nature of IRAS 23385. While most of the forbidden fine structure transitions are blueshifted, [NeII] and [NeIII] peak at the source velocity toward the MIR source A/mmA2 suggesting that the emission is originating from closer to the protostar. Conclusions. The warm and cold gas traced by MIR and mm observations, respectively, are strongly linked in IRAS 23385. The outflows traced by MIR H2 lines have molecular counterparts in the mm regime. Despite the presence of multiple powerful outflows that cause dense and hot shocks, a cold dense envelope still allows star formation to further proceed. To study and fully understand the spatially resolved MIR properties, a representative sample of low- and high-mass protostars has to be probed using JWST.
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| 7. |
- Oh, Juhwan, et al.
(author)
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Mobility restrictions were associated with reductions in COVID-19 incidence early in the pandemic : evidence from a real-time evaluation in 34 countries
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Most countries have implemented restrictions on mobility to prevent the spread of Coronavirus disease-19 (COVID-19), entailing considerable societal costs but, at least initially, based on limited evidence of effectiveness. We asked whether mobility restrictions were associated with changes in the occurrence of COVID-19 in 34 OECD countries plus Singapore and Taiwan. Our data sources were the Google Global Mobility Data Source, which reports different types of mobility, and COVID-19 cases retrieved from the dataset curated by Our World in Data. Beginning at each country's 100th case, and incorporating a 14-day lag to account for the delay between exposure and illness, we examined the association between changes in mobility (with January 3 to February 6, 2020 as baseline) and the ratio of the number of newly confirmed cases on a given day to the total number of cases over the past 14 days from the index day (the potentially infective 'pool' in that population), per million population, using LOESS regression and logit regression. In two-thirds of examined countries, reductions of up to 40% in commuting mobility (to workplaces, transit stations, retailers, and recreation) were associated with decreased cases, especially early in the pandemic. Once both mobility and incidence had been brought down, further restrictions provided little additional benefit. These findings point to the importance of acting early and decisively in a pandemic.
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| 8. |
- Quintino, Luis, et al.
(author)
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Destabilizing Domains Enable Long-Term and Inert Regulation of GDNF Expression in the Brain
- 2018
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In: Molecular Therapy - Methods and Clinical Development. - : Elsevier BV. - 2329-0501. ; 11, s. 29-39
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Journal article (peer-reviewed)abstract
- Regulation of therapeutic transgene expression can increase the safety of gene therapy interventions, especially when targeting critical organs such as the brain. Although several gene expression systems have been described, none of the current systems has the required safety profile for clinical applications. Our group has previously adapted a system for novel gene regulation based on the destabilizing domain degron technology to successfully regulate glial cell-line derived neurotrophic factor in the brain (GDNF-F-DD). In the present study, we used GDNF-F-DD as a proof-of-principle molecule to fully characterize DD regulation in the brain. Our results indicate that DD could be regulated in a dose-dependent manner. In addition, GDNF-F-DD could also be induced in vivo repeatedly, without loss of activity or efficacy in vivo. Finally, DD regulation was able to be sustained for 24 weeks without loss of expression or any overt toxicity. The present study shows that DD has great potential to regulate gene expression in the brain.
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| 9. |
- Quintino, Luis, et al.
(author)
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GDNF-mediated rescue of the nigrostriatal system depends on the degree of degeneration
- 2019
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In: Gene Therapy. - : Springer Science and Business Media LLC. - 0969-7128 .- 1476-5462. ; 26:1-2, s. 57-64
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Journal article (peer-reviewed)abstract
- Glial cell-line derived neurotrophic factor (GDNF) is a promising therapeutic molecule to treat Parkinson’s disease. Despite an excellent profile in experimental settings, clinical trials testing GDNF have failed. One of the theories to explain these negative outcomes is that the clinical trials were done in late-stage patients that have advanced nigrostriatal degeneration and may therefore not respond to a neurotrophic factor therapy. Based on this idea, we tested if the stage of nigrostriatal degeneration is important for GDNF-based therapies. Lentiviral vectors expressing regulated GDNF were delivered to the striatum of rats to allow GDNF expression to be turned on either while the nigrostriatal system was degenerating or after the nigrostriatal system had been fully lesioned by 6-OHDA. In the group of animals where GDNF expression was on during degeneration, neurons were rescued and there was a reversal of motor deficits. Turning GDNF expression on after the nigrostriatal system was lesioned did not rescue neurons or reverse motor deficits. In fact, these animals were indistinguishable from the control groups. Our results suggest that GDNF can reverse motor deficits and nigrostriatal pathology despite an ongoing nigrostriatal degeneration, if there is still a sufficient number of remaining neurons to respond to therapy.
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| 10. |
- Rocha, W. R.M., et al.
(author)
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JWST Observations of Young protoStars (JOYS+): Detecting icy complex organic molecules and ions: I. CH4, SO2, HCOO, OCN, H2CO, HCOOH, CH3CH2OH, CH3CHO, CH3OCHO, and CH3COOH
- 2024
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 683
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Journal article (peer-reviewed)abstract
- Context. Complex organic molecules (COMs) are ubiquitously detected in the gas phase and thought to be mostly formed on icy grains. Nevertheless, there have not been any unambiguous detections of COMs larger than CH3OH in ices reported thus far. Exploring this matter in greater detail has now become possible with the unprecedented possibilities offered by the James Webb Space Telescope (JWST) within the infrared (IR) spectral range with its very high sensitivity and spectral resolution in the critical 5 10 μm range, the fingerprint region of oxygen-bearing COMs. Aims. In the JWST Observations of Young protoStars (JOYS+) program, more than 30 protostars are undergoing observation with the Medium Resolution Spectrograph (MRS) of the Mid-IR Instrument (MIRI). The goal of this study is to comprehensively explore the COMs ice signatures in one low- and one high-mass protostar: NGC 1333 IRAS 2A and IRAS 23385+6053, respectively. Methods. We performed global continuum and silicate subtractions of the MIRI-MRS spectra, followed by a local continuum subtraction in optical depth scale in the range around 6.8 and 8.6 μm, the ice COM fingerprint region. We explored different choices for the local continuum and silicate subtraction. Next, we fit the observational data with a large sample of available IR laboratory ice spectra. We used the ENIIGMA fitting tool, a genetic algorithm-based code that not only finds the best fit between the lab data and the observations, but also performs a statistical analysis of the solutions, such as deriving the confidence intervals and quantifying fit degeneracy. Results. We report the best fits for the spectral ranges between 6.8 and 8.6 μm in NGC 1333 IRAS 2A and IRAS 23385+6053, originating from simple molecules and COMs, as well as negative ions. Overall, we find that ten chemical species are needed to reproduce the astronomical data. The strongest feature in this range (7.7 μm) is dominated by CH4, with contributions from SO2 and OCN. Our results indicate that the 7.2 and 7.4 μm bands are mostly dominated by HCOO. We also find statistically robust detections of COMs based on multiple bands, most notably, CH3CHO, CH3CH2OH, and CH3OCHO. We also report a likely detection of CH3COOH. Based on the ice column density ratios between CH3CH2OH and CH3CHO of NGC 1333 IRAS 2A and IRAS 23385+6053, we find compelling evidence that these COMs are formed on icy grains. Finally, the derived ice abundances for NGC 1333 IRAS 2A correlate well with those in comet 67P/GC within a factor of 5. Conclusions. Based on the high-quality JWST (MIRI-MRS) spectra, we conclude that COMs are present in interstellar ices, thus providing additional proof for the solid-state origin of these species in star-forming regions. In addition, the good correlation between the ice abundances in comet 67P and NGC 1333 IRAS 2A is fully in line with the idea that cometary COMs may be inherited from the early protostellar phases to a significant extent.
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