Randall K. Smith

AtomDB: Atomic data for X-ray astronomy

This paper outlines some of the progress in the AtomDB project, which aims to model X-ray emission from hot, collisionally ionized plasmas. We define data formats for ionization, recombination, photo-ionization and autoionization. We discuss the inclusion of the XSTAR database in AtomDB, in particular using the photoionization data, and the progress in preparing a full non-equilibrium ionization model for use by modelers and observers.

Arcus: the x-ray grating spectrometer explorer (Conference Presentation)

Arcus, a Medium Explorer (MIDEX) mission, was selected by NASA for a Phase A study in August 2017. The observatory provides high-resolution soft X-ray spectroscopy in the 12-50 A bandpass with unprecedented sensitivity: effective areas of >350 cm^2 and spectral resolution >2500 at the energies of O VII and O VIII for z=0-0.3. The Arcus key science goals are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, groups, and clusters, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback and (3) to explore how stars, circumstellar disks and exoplanet atmospheres form and evolve. Arcus relies upon the same 12m focal length grazing-incidence silicon pore X-ray optics (SPO) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. Arcus will be launched into an ~ 7 day 4:1 lunar resonance orbit, resulting in high observing efficiency, low particle background and a favorable thermal environment. Mission operations are straightforward, as most observations will be long (~100 ksec), uninterrupted, and pre-planned. The baseline science mission will be completed in <2 years, although the margin on all consumables allows for 5+ years of operation.

Capturing the many faces of an exploded star: communicating complex and evolving astronomical data

This study explored how different presentations of an object in deep space affect understanding, engagement, and aesthetic appreciation. A total of n = 2,502 respondents to an online survey were randomly assigned to one of 11 versions of Cassiopeia A, comprising 6 images and 5 videos ranging from 3 s to approximately 1 min. Participants responded to intial items regarding what the image looked like, the aesthetic appeal of the image, perceptions of understanding, and how much the participant wanted to learn more. After the image was identified, participants indicated the extent to which the label increased understanding and how well the image represented the object. A final item asked for questions about the image for an atronomer. Results suggest that alternative types of images can and should be used, provided they are accompanied by explanations. Qualitative data indicated that explanations should include information about colors used, size, scale, and location of the object. The results are discussed in terms of science communication to the public in the face of increasing use of technology. Abstract

Data for non equilibrium modeling with AtomDB

AtomDB version 3.0 is available as a beta release. The main additions to this release are additions for analyzing non-equilibrium collisional plasmas, in particular ionizing plasmas. This includes revisions to the emission code APEC, and new data generation and collection. Here we briefly outline the new model, and describe in detail the new data formats.