PDRs4All II: JWST's NIR and MIR imaging view of the Orion Nebula

The JWST has captured the most detailed and sharpest infrared images ever taken of the inner region of the Orion Nebula, the nearest massive star formation region, and a prototypical highly irradiated dense photo-dissociation region (PDR). We investigate the fundamental interaction of far-ultraviolet photons with molecular clouds. The transitions across the ionization front (IF), dissociation front (DF), and the molecular cloud are studied at high-angular resolution. These transitions are relevant to understanding the effects of radiative feedback from massive stars and the dominant physical and chemical processes that lead to the IR emission that JWST will detect in many Galactic and extragalactic environments. Due to the proximity of the Orion Nebula and the unprecedented angular resolution of JWST, these data reveal that the molecular cloud borders are hyper structured at small angular scales of 0.1-1" (0.0002-0.002 pc or 40-400 au at 414 pc). A diverse set of features are observed such as ridges, waves, globules and photoevaporated protoplanetary disks. At the PDR atomic to molecular transition, several bright features are detected that are associated with the highly irradiated surroundings of the dense molecular condensations and embedded young star. Toward the Orion Bar PDR, a highly sculpted interface is detected with sharp edges and density increases near the IF and DF. This was predicted by previous modeling studies, but the fronts were unresolved in most tracers. A complex, structured, and folded DF surface was traced by the H2 lines. This dataset was used to revisit the commonly adopted 2D PDR structure of the Orion Bar. JWST provides us with a complete view of the PDR, all the way from the PDR edge to the substructured dense region, and this allowed us to determine, in detail, where the emission of the atomic and molecular lines, aromatic bands, and dust originate

PDRs4All III: JWST's NIR spectroscopic view of the Orion Bar

(Abridged) We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the HII region to the atomic PDR (crossing the ionisation front (IF)), and the subsequent transition to the molecular PDR (crossing the dissociation front (DF)). We use high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science Program. The NIRSpec data reveal a forest of lines including, but not limited to, HeI, HI, and CI recombination lines, ionic lines, OI and NI fluorescence lines, Aromatic Infrared Bands (AIBs including aromatic CH, aliphatic CH, and their CD counterparts), CO2 ice, pure rotational and ro-vibrational lines from H2, and ro-vibrational lines HD, CO, and CH+, most of them detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. We observe numerous smaller scale structures whose typical size decreases with distance from Ori C and IR lines from CI, if solely arising from radiative recombination and cascade, reveal very high gas temperatures consistent with the hot irradiated surface of small-scale dense clumps deep inside the PDR. The H2 lines reveal multiple, prominent filaments which exhibit different characteristics. This leaves the impression of a "terraced" transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star- and planet formation as well as galaxy evolution.Comment: 52 pages, 30 figures, submitted to A&

PDRs4All IV. An embarrassment of riches: Aromatic infrared bands in the Orion Bar

(Abridged) Mid-infrared observations of photodissociation regions (PDRs) are dominated by strong emission features called aromatic infrared bands (AIBs). The most prominent AIBs are found at 3.3, 6.2, 7.7, 8.6, and 11.2 $\mu$m. The most sensitive, highest-resolution infrared spectral imaging data ever taken of the prototypical PDR, the Orion Bar, have been captured by JWST. We provide an inventory of the AIBs found in the Orion Bar, along with mid-IR template spectra from five distinct regions in the Bar: the molecular PDR, the atomic PDR, and the HII region. We use JWST NIRSpec IFU and MIRI MRS observations of the Orion Bar from the JWST Early Release Science Program, PDRs4All (ID: 1288). We extract five template spectra to represent the morphology and environment of the Orion Bar PDR. The superb sensitivity and the spectral and spatial resolution of these JWST observations reveal many details of the AIB emission and enable an improved characterization of their detailed profile shapes and sub-components. While the spectra are dominated by the well-known AIBs at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 $\mu$m, a wealth of weaker features and sub-components are present. We report trends in the widths and relative strengths of AIBs across the five template spectra. These trends yield valuable insight into the photochemical evolution of PAHs, such as the evolution responsible for the shift of 11.2 $\mu$m AIB emission from class B$_{11.2}$ in the molecular PDR to class A$_{11.2}$ in the PDR surface layers. This photochemical evolution is driven by the increased importance of FUV processing in the PDR surface layers, resulting in a "weeding out" of the weakest links of the PAH family in these layers. For now, these JWST observations are consistent with a model in which the underlying PAH family is composed of a few species: the so-called 'grandPAHs'.Comment: 25 pages, 10 figures, to appear in A&

A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, impacting planet formation within the disks. We report JWST and Atacama Large Millimetere Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modelling their kinematics and excitation allows us to constrain the physical conditions within the gas. We quantify the mass-loss rate induced by the FUV irradiation, finding it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk

PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars

22 pags., 8 figs., 1 tab.Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1-3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter-and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.Support for JWST-ERS program ID 1288 was provided through grants from the STScI under NASA contract NAS5-03127 to STScI (K.G., D.V.D.P., M.R.), Univ. of Maryland (M.W., M.P.), Univ. of Michigan (E.B., F.A.), and Univ. of Toledo (T.S.-Y.L.). O.B. and E.H. are supported by the Programme National “Physique et Chimie du Milieu Interstellaire” (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES, and through APR grants 6315 and 6410 provided by CNES. E. P. and J.C. acknowledge support from the National Science and Engineering Council of Canada (NSERC) Discovery Grant program (RGPIN-2020-06434 and RGPIN-2021-04197 respectively). E.P. acknowledges support from a Western Strategic Support Accelerator Grant (ROLA ID 0000050636). J.R.G. and S.C. thank the Spanish MCINN for funding support under grant PID2019-106110GB-I00. Work by M.R. and Y.O. is carried out within the Collaborative Research Centre 956, subproject C1, funded by the Deutsche Forschungsgemeinschaft (DFG)—project ID 184018867. T.O. acknowledges support from JSPS Bilateral Program, grant No. 120219939. M.P. and M.W. acknowledge support from NASA Astrophysics Data Analysis Program award #80NSSC19K0573. C.B. is grateful for an appointment at NASA Ames Research Center through the San José State University Research Foundation (NNX17AJ88A) and acknowledges support from the Internal Scientist Funding Model (ISFM) Directed Work Package at NASA Ames titled: “Laboratory Astrophysics—The NASA Ames PAH IR Spectroscopic Database.”Peer reviewe

Μελέτη της δραστηριότητας σε ένα αντιπροσωπευτικό δείγμα κοντινών γαλαξιών που παρουσιάζουν αστρογέννεση χρησιμοποιώντας παρατηρήσεις σε διάφορα μήκη κύματος

This thesis presents the activity demographics of an Infrared-selected sample of galaxies in the local Universe. We investigate how activity classification depends on the proportion of the host galaxy’s light that is included in the nuclear spectral extraction aperture using observed long-slit spectra and spectra from simulated elliptical apertures of different sizes. We find that starlight subtraction can mitigate but not remove the effect of host galaxy contamination in the nuclear aperture. Furthermore, galaxies with extranuclear star formation can show higher [OIII]/Hβ ratios with increasing aperture, in contrast to the naive expectation that integrated light will only dilute the nuclear emission lines, and hence will have a different placement in the diagnostic diagrams and on certain occasions a different classification. We present activity demographics and host-galaxy properties of IR-selected galaxies in the local Universe using the representative Star Formation Reference Survey. Our classification scheme is based on a combination of the three optical emission-line diagrams (BPT) and IR-color diagnostics. Using the well defined weights of the SFRS galaxies with respect to the parent PSCz sample, we find that the PSCz comprises 71% HII galaxies, 13% Seyferts, 3% Transition Objects (TOs), and 13% LINERs. We derive nuclear star-formation rates and gas-phase metallicities for the star-forming galaxies, and measure abundance gradients for a subset of 12 face-on galaxies. The majority of SFGs show a narrow range of metallicities, close to solar, and flat metallicity profiles. We find that based on their host-galaxy and nuclear properties, the dominant ionizing source in the SFRS (PSCz) TOs is star-forming activity. LINERs are found mostly in massive hosts with low L(60μm), low dust temperatures, and low LHα surface densities, indicating older stellar populations as their main ionizing source rather than AGN activity. We describe a sub-galactic main sequence (SGMS) relating star-formation rate surface density and stellar mass density for distinct regions within star forming galaxies, including their nuclei. We demonstrate that the SGMS holds down to ∼1 kpc scales with a slope of α = 0.91 and a dispersion of 0.31 dex, similar to the galaxy-wide main sequence. The SGMS slope depends on galaxy morphology, with late-type galaxies having steeper slopes. The SGMS constructed from sub-regions of individual galaxies has on average the same characteristics as the composite SGMS from all galaxies. For nearly all galaxies, both the SFR and stellar mass peak in the nucleus, indicating that circumnuclear clusters are among the most actively star-forming regions in the galaxy and the most massive. The nuclear SFR also correlates with total galaxy mass, forming a distinct sequence from the standard MS of star-formation.Αυτή η διδακτορική διατριβή παρουσιάζει την ταξινόμηση ενός δείγματος γαλαξιών με έντονη εκπομπή στο υπέρυθρο, βάση της δραστηριότητας στον πυρήνα τους. Αρχικά διερευνούμε τον τρόπο με τον οποίο η πυρηνική ταξινόμηση των γαλαξιών εξαρτάται από το ποσοστό του φωτός από το υπόλοιπο σώμα του γαλαξία, το οποίο υπεισέρχεται στη σχισμή που εξάγεται το πυρηνικό φάσμα των γαλαξιών. Χρησιμοποιούμε φάσματα από φασματογράφο σχισμής καθώς και προσομοιώσεις φασμάτων που έχουν ληφθεί από ελλειπτικές οπές διαφορετικών μεγεθών. Βρίσκουμε ότι οι μέθοδοι αφαίρεσης του αστρικού φωτός από το πυρηνικό φάσμα εκπομπής του γαλαξία μπορούν να περιορίσουν αλλά όχι να αφαιρέσουν απόλυτα την εισχώρηση του φωτός από το σώμα του γαλαξία στην πυρηνική σχισμή. Επιπλέον, γαλαξίες με έντονη εξωπυρηνική αστρογένεση παρουσιάζουν μεγαλύτερους λόγους [OIII]/Hβ καθώς αυξάνεται το μέγεθος της πυρηνικής σχισμής της φασματικής εξαγωγής, σε αντίθεση με την κοινή αντίληψη ότι το επιπρόσθετο φως από το σώμα του γαλαξία θα μειώσει τους λόγους γραμμών εκπομπής του πυρήνα, με αποτέλεσμα να παρουσιάζουν διαφορετική θέση στα διαγνωστικά διαγράμματα και σε κάποιες περιπτώσεις διαφορετική ταξινόμηση. Παρουσιάζουμε τα δημογραφικά στοιχεία της πυρηνικής δραστηριότητας γαλαξιών με έντονη εκπομπή στο υπέρυθρο στο κοντινό Σύμπαν, χρησιμοποιώντας το αντιπροσωπευτικό δείγμα του Star Formation Reference Survey. Το πλαίσιο ταξινόμησης που χρησιμοποιούμε βασίζεται σε ένα συνδυασμό των τριών διαγνωστικών οπτικών γραμμών εκπομπής (BPT) καθώς και διαγνωστικών υπέρυθρων χρωμάτων. Χρησιμοποιώντας τα στατιστικά βάρη που έχουν αποδοθεί στους γαλαξίες του SFRS σε σχέση με το ευρύτερο δείγμα γαλαξιών PSCz από το οποίο προέκυψαν βρίσκουμε ότι το PSCz αποτελείται από 71% HII γαλαξίες, 13% Seyferts, 3% μεταβατικά αντικείμενα (TOs), και 13% LINERs. Για τους HΙΙ γαλαξίες υπολογίζουμε τον ρυθμό αστρογένεσης και την μεταλλικότητα του αερίου στον πυρήνα τους και υπολογίζουμε βαθμίδες μεταλλικότητας για 12 γαλαξίες. Οι περισσότεροι HΙΙ γαλαξίες έχουν ένα μικρό εύρος τιμών μεταλλικότητας κοντά στην ηλιακή και επίπεδες βαθμίδες μεταλλικότητας. Βρίσκουμε με βάση τα χαρακτηριστικά του σώματος και του πυρήνα των γαλαξιών ότι η κυρίαρχη πηγή παραγωγής ενέργειας για τα SFRS (PSCz) TOs είναι η δραστηριότητα αστρογένεσης. Οι LINERs βρίσκονται κατά κύριο λόγο σε γαλαξίες μεγάλης μάζας με χαμηλές τιμές L(60μm), χαμηλές θερμοκρασίες σκόνης, και χαμηλές τιμές επιφανειακής πυκνότητας LHα, υποδηλώνοντας ως βασική πηγή ιονισμού αστρικούς πληθυσμούς μεγάλης ηλικίας και όχι AGN δραστηριότητα. Περιγράφουμε μία κύρια ακολουθία σε διακριτές περιοχές εντός των γαλαξιών (SGMS) συσχετίζοντας την επιφανειακή πυκνότητα του ρυθμού αστρογένεσης και της επιφανειακής πυκνότητας αστρικής μάζας για διακριτές περιοχές γαλαξιών αστρογένεσης, συμπεριλαμβανομένων των πυρήνων τους. Η SGMS ορίζεται σε κλίμακες έως και ~1 kpc με κλίση α=0.91 και διασπορά 0.31 dex. Η κλίση της SGMS εξαρτάται από τη μορφολογία των γαλαξιών, με τους μεταγενέστερου τύπου σπειροειδείς να έχουν μεγαλύτερη κλίση από τους προγενέστερου τύπου σπειροειδείς. Η SGMS η οποία προκύπτει από τις διακριτές περιοχές κάθε γαλαξία ξεχωριστά έχει κατά μέσω όρο τα ίδια χαρακτηριστικά με την SGMS που προκύπτει από όλους τους γαλαξίες μαζί. Σχεδόν για όλους τους γαλαξίες τόσο η επιφανειακή πυκνότητα του ρυθμού αστρογένεσης όσο και της αστρικής μάζας έχει τη μέγιστη τιμή της στον πυρήνα των γαλαξιών, υποδηλώνοντας ότι τα σμήνη γύρω από τον πυρήνα είναι από τα πιο ενεργές περιοχές αστρογένεσης στους γαλαξίες και οι πιο μαζικές. Ο ρυθμός αστρογένεσης στον πυρήνα συσχετίζεται επίσης και με την συνολική αστρική μάζα των γαλαξιών, δημιουργώντας μια ξεχωριστή ακολουθία από την πρότυπη κυρία ακολουθία (MS) αστρογένεσης

Myocardial inotropic reserve: An old twist that constitutes a reliable index in the modern era of heart failure

Current national and international guidelines, including those of the European Society of Cardiology, recognize that the assessment of prognosis should be a part of the standard management for patients with chronic heart failure (CHF). However, these same guidelines recognize the inherent difficulty of this process. A variety of factors contribute to this difficulty, including the varying etiology, frequent co-morbidity and, perhaps most importantly, huge inter-individual variability in the disease progression and outcome. Although CHF is chronic, it is also a condition in which significant proportions of patients experience apparently ‘sudden’ death, which almost certainly contributes to our difficulty in assessing individual patient prognosis. A useful tool for the risk stratification of heart failure patients is dobutamine stress echocardiography (DSE), which determines the myocardial viability in ischemic cardiomyopathy and myocardial contractile reserve in idiopathic cardiomyopathy

The Role of Ionizing Radiation for Diagnosis and Treatment against COVID-19: Evidence and Considerations

The Coronavirus disease 2019 (COVID-19) pandemic continues to spread worldwide with over 260 million people infected and more than 5 million deaths, numbers that are escalating on a daily basis. Frontline health workers and scientists diligently fight to alleviate life-threatening symptoms and control the spread of the disease. There is an urgent need for better triage of patients, especially in third world countries, in order to decrease the pressure induced on healthcare facilities. In the struggle to treat life-threatening COVID-19 pneumonia, scientists have debated the clinical use of ionizing radiation (IR). The historical literature dating back to the 1940s contains many reports of successful treatment of pneumonia with IR. In this work, we critically review the literature for the use of IR for both diagnostic and treatment purposes. We identify details including the computed tomography (CT) scanning considerations, the radiobiological basis of IR anti-inflammatory effects, the supportive evidence for low dose radiation therapy (LDRT), and the risks of radiation-induced cancer and cardiac disease associated with LDRT. In this paper, we address concerns regarding the effective management of COVID-19 patients and potential avenues that could provide empirical evidence for the fight against the disease

The Role of Ionizing Radiation for Diagnosis and Treatment against COVID-19: Evidence and Considerations

The Coronavirus disease 2019 (COVID-19) pandemic continues to spread worldwide with over 260 million people infected and more than 5 million deaths, numbers that are escalating on a daily basis. Frontline health workers and scientists diligently fight to alleviate life-threatening symptoms and control the spread of the disease. There is an urgent need for better triage of patients, especially in third world countries, in order to decrease the pressure induced on healthcare facilities. In the struggle to treat life-threatening COVID-19 pneumonia, scientists have debated the clinical use of ionizing radiation (IR). The historical literature dating back to the 1940s contains many reports of successful treatment of pneumonia with IR. In this work, we critically review the literature for the use of IR for both diagnostic and treatment purposes. We identify details including the computed tomography (CT) scanning considerations, the radiobiological basis of IR anti-inflammatory effects, the supportive evidence for low dose radiation therapy (LDRT), and the risks of radiation-induced cancer and cardiac disease associated with LDRT. In this paper, we address concerns regarding the effective management of COVID-19 patients and potential avenues that could provide empirical evidence for the fight against the disease