There\u27s a little street in heaven that they call Broadway

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Classification and analysis of emission-line galaxies using mean field independent component analysis

We present an analysis of the optical spectra of narrow emission-line galaxies, based on mean field independent component analysis (MFICA). Samples of galaxies were drawn from the Sloan Digital Sky Survey (SDSS) and used to generate compact sets of `continuum' and `emission-line' component spectra. These components can be linearly combined to reconstruct the observed spectra of a wider sample of galaxies. Only 10 components - five continuum and five emission line - are required to produce accurate reconstructions of essentially all narrow emission-line galaxies; the median absolute deviations of the reconstructed emission-line fluxes, given the signal-to-noise ratio (S/N) of the observed spectra, are 1.2-1.8 sigma for the strong lines. After applying the MFICA components to a large sample of SDSS galaxies we identify the regions of parameter space that correspond to pure star formation and pure active galactic nucleus (AGN) emission-line spectra, and produce high S/N reconstructions of these spectra. The physical properties of the pure star formation and pure AGN spectra are investigated by means of a series of photoionization models, exploiting the faint emission lines that can be measured in the reconstructions. We are able to recreate the emission line strengths of the most extreme AGN case by assuming the central engine illuminates a large number of individual clouds with radial distance and density distributions, f(r) ~ r^gamma and g(n) ~ n^beta, respectively. The best fit is obtained with gamma = -0.75 and beta = -1.4. From the reconstructed star formation spectra we are able to estimate the starburst ages. These preliminary investigations serve to demonstrate the success of the MFICA-based technique in identifying distinct emission sources, and its potential as a tool for the detailed analysis of the physical properties of galaxies in large-scale surveys.Comment: MNRAS accepted. 29 pages, 24 figures, 3 table

Interpreting the Ionization Sequence in AGN Emission-Line Spectra

We investigate the physical cause of the great range in the ionization level seen in the spectra of narrow lined active galactic nuclei (AGN). Mean field independent component analysis identifies examples of individual SDSS galaxies whose spectra are not dominated by emission due to star formation (SF), which we designate as AGN. We assembled high S/N ratio composite spectra of a sequence of these AGN defined by the ionization level of their narrow-line regions (NLR), extending down to very low-ionization cases. We used a local optimally emitting cloud (LOC) model to fit emission-line ratios in this AGN sequence. These included the weak lines that can be measured only in the co-added spectra, providing consistency checks on strong line diagnostics. After integrating over a wide range of radii and densities our models indicate that the radial extent of the NLR is the major parameter in determining the position of high to moderate ionization AGN along our sequence, providing a physical interpretation for their systematic variation. Higher ionization AGN contain optimally emitting clouds that are more concentrated towards the central continuum source than in lower ionization AGN. Our LOC models indicate that for the objects that lie on our AGN sequence, the ionizing luminosity is anticorrelated with the NLR ionization level, and hence anticorrelated with the radial concentration and physical extent of the NLR. A possible interpretation that deserves further exploration is that the ionization sequence might be an age sequence where low ionization objects are older and have systematically cleared out their central regions by radiation pressure. We consider that our AGN sequence instead represents a mixing curve of SF and AGN spectra, but argue that while many galaxies do have this type of composite spectra, our AGN sequence appears to be a special set of objects with negligible SF excitation.Comment: 57 pages; 18 figures, accepted by MNRA

Ethical, regulatory, and practical barriers to COVID-19 research: A stakeholder-informed inventory of concerns

INTRODUCTION: SARS-CoV-2 (COVID-19) has caused death and economic injury around the globe. The urgent need for COVID-19 research created new ethical, regulatory, and practical challenges. The next public health emergency could be worse than COVID-19. We must learn about these challenges from the experiences of researchers and Research Ethics Committee professionals responsible for these COVID-19 studies to prepare for the next emergency. MATERIALS AND METHODS: We conducted an online survey to identify the ethical, oversight, and regulatory challenges of conducting COVID-19 research during the early pandemic, and proposed solutions for overcoming these barriers. Using criterion-based, convenience sampling, we invited researchers who proposed or conducted COVID-19 research to complete an anonymous, online survey about their experiences. We administered a separate but related survey to Institutional Review Board (IRB) professionals who reviewed COVID-19 research studies. The surveys included open-ended and demographic items. We performed inductive content analysis on responses to open-ended survey questions. RESULTS: IRB professionals (n = 143) and researchers (n = 211) described 19 types of barriers to COVID-19 research, related to 5 overarching categories: policy and regulatory, biases and misperceptions, institutional and inter-institutional conflicts, risks of harm, and pressure of the pandemic. Researchers and IRB professionals described 8 categories of adaptations and solutions to these challenges: enacting technological solutions; developing protocol-based solutions; disposition and team management; establishing and communicating appropriate standards; national guidance and leadership; maintaining high standards; prioritizing studies before IRB review; and identifying and incorporating experts. DISCUSSION AND CONCLUSIONS: This inventory of challenges represents ongoing barriers to studying the current pandemic, and they represent a risk to research during future public health emergencies. Delays in studies of a pandemic during a pandemic threatens the health and safety of the public. We urge the development of a national working group to address these issues before the next public health emergency arises

Observational constraints on the progenitor metallicities of core-collapse supernovae

We present constraints on the progenitor metallicities of core-collapse supernovae. To date, nearly all metallicity constraints have been inferred from indirect methods such as metallicity gradients in host galaxies, luminosities of host galaxies, or derived global galaxy metallicities. Here, progenitor metallicities are derived from optical spectra taken at the sites of nearby supernovae, from the ratio of strong emission lines found in their host HII regions.We present results from the spectra of 74 host HII regions and discuss the implications that these have on the nature of core-collapse supernova progenitors. Overall, while we find that the mean metallicity of type Ibc environments is higher than that of type II events, this difference is smaller than observed in previous studies. There is only a 0.06 dex difference in the mean metallicity values, at a statistical significance of ~1.5 sigma, while using a KS-test we find that the two metallicity distributions are marginally consistent with being drawn from the same parent population (probability >10%). This argues that progenitor metallicity is not a dominant parameter in deciding supernovae type, with progenitor mass and/or binarity playing a much more significant role.Comment: ACCEPTED for publication in MNRA

Searching for an Intermediate Mass Black Hole in the Blue Compact Dwarf galaxy MRK 996

The possibility is explored that accretion on an intermediate mass black hole contributes to the ionisation of the interstellar medium of the Compact Blue Dwarf galaxy MRK996. Chandra observations set tight upper limits (99.7 per cent confidence level) in both the X-ray luminosity of the posited AGN, Lx(2-10keV)<3e40erg/s, and the black hole mass, <1e4/\lambda Msolar, where \lambda, is the Eddington ratio. The X-ray luminosity upper limit is insufficient to explain the high ionisation line [OIV]25.89\mu m, which is observed in the mid-infrared spectrum of the MRK996 and is proposed as evidence for AGN activity. This indicates that shocks associated with supernovae explosions and winds of young stars must be responsible for this line. It is also found that the properties of the diffuse X-ray emission of MRK996 are consistent with this scenario, thereby providing direct evidence for shocks that heat the galaxy's interstellar medium and contribute to its ionisation.Comment: Submitted to MNRA

Professional Decision-Making in Research (PDR): The validity of a new measure

In this paper, we report on the development and validity of the Professional Decision-Making in Research (PDR) measure, a vignette-based test that examines decision-making strategies used by investigators when confronted with challenging situations in the context of empirical research. The PDR was administered online with a battery of validity measures to a group of NIH-funded researchers and research trainees who were diverse in terms of age, years of experience, types of research, and race. The PDR demonstrated adequate reliability (alpha = .84) and parallel form correlation (r = .70). As hypothesized, the PDR was significantly negatively correlated with narcissism, cynicism, moral disengagement, and compliance disengagement; it was not correlated with socially desirable responding. In regression analysis, the strongest predictors of higher PDR scores were low compliance disengagement, speaking English as a native language, conducting clinical research with human subjects, and low levels of narcissism. Given that the PDR was written at an eighth grade reading level to be suitable for use with English as a second language participants and that only one-fourth of items focused on clinical research, further research into the possible roles of culture and research ethics training across specialties is warranted. This initial validity study demonstrates the potential usefulness of the PDR as an educational outcome assessment measure and a research instrument for studies on professionalism and integrity in research

A randomized implementation trial to increase adoption of evidence-informed consent practices

INTRODUCTION: Several evidence-informed consent practices (ECPs) have been shown to improve informed consent in clinical trials but are not routinely used. These include optimizing consent formatting, using plain language, using validated instruments to assess understanding, and involving legally authorized representatives when appropriate. We hypothesized that participants receiving an implementation science toolkit and a social media push would have increased adoption of ECPs and other outcomes. METHODS: We conducted a 1-year trial with clinical research professionals in the USA ( RESULTS: Participants who engaged more with the toolkit were more likely to have tried to implement an ECP during the trial than participants less engaged with the toolkit or the active control group. However, there were no significant differences in the adoption of ECPs, intention to adopt, or positive attitudes. Participants reported the toolkit and social media push were satisfactory, and participating increased their awareness of ECPs. However, they reported lacking the time needed to engage with the toolkit more fully. CONCLUSIONS: Using an implementation science approach to increase the use of ECPs was only modestly successful. Data suggest that having institutional review boards recommend or require ECPs may be an effective way to increase their use

Discovery of kpc-scale line emission in barred galaxies, not linked to AGN or star formation

We present an analysis of the optical line emission from nearby barred galaxies, and in particular look at the radial range occupied by the bar. In many cases this region is marked by what we term a 'star formation desert', with a marked deficit of HII regions in optical narrow-band H-alpha imaging. Here we present long-slit spectroscopy revealing that such regions do have line emission, but that it is low-level, spatially smooth and almost ubiquitous. The relative strengths of the H-alpha and the spectrally adjacent [NII] lines in the regions are completely discrepant from those associated with star formation regions, and more closely match expectations for 'LINER' regions. We quantify the total line emission from these extended, kpc-scale regions, and determine the spurious contribution it would make to the determined star formation rate of these galaxies if interpreted as normal H-alpha emission. We concur with previous studies that link this LINER emission to old stellar populations, e.g. post-asymptotic giant branch stars, and propose these strongly-barred early-type spirals as a prime location for further tests of such emission