Key Science Topics Research Articles

An Arcus view of stellar space weather

AbstractArcus is a Medium Explorer (MIDEX) NASA mission to be proposed near the end of 2021. One of the three science goals for Arcus is to explore how stars, circumstellar disks, and exoplanet atmospheres form and evolve. The mission provides high‐resolution, soft X‐ray spectroscopy with required effective area cm2 and resolving power . Key science topics discussed here are the structure and heating of stellar coronae across the HR diagram and magnetic accretion onto young stars. These studies will contribute to our understanding of the impact of stellar space weather on exoplanet atmospheres.

Gardens as Science Learning Contexts Across Educational Stages: Learning Assessment Based on Students' Graphic Representations.

The educational use of daily-life contexts is considered a valuable strategy to promote meaningful science learning, since it facilitates the establishment of connections between previous knowledge, personal interests, and new learning. The aim of this work is to provide evidence to support the presence of gardens at educational centers, by assessing key science topics whose learning is promoted at the pre-school, primary, secondary, and university stages. To this end, we analyzed the paired graphic representations of “a garden” that students drew both before and after their participation in a garden-based learning program. Firstly, we obtained the frequency of appearance of every represented element, and afterward characterized the level of change between paired graphic representations. Sample size was of 24–19–25–29 pairs per stage, respectively. Across all stages, an overall improvement in students’ graphic expression was observed, which can be attributed to their experience in the space. At the pre-school stage, the garden favored the establishment of some simple cause-effect relationships which were consolidated at the primary stage, and provided a climate of motivation and affectivity that was evident in the final drawings, given the enormous quantity of details represented, the level of the finished product, and the careful combination and variety of colors. The presence of elements related to water notably increased in final graphic representations from pre-school, primary, and secondary education, thus evidencing that the use of gardens facilitates an approach to responsible water management. At the university stage, students initially demonstrated good knowledge of conventional agriculture, while the gardening experience -which was based on permaculture practices- helped evolve their ideas toward an alternative model of cultivation. The most prevalent science learning across all stages was related to plant knowledge, particularly to their anatomical traits and diversity. Finally, the role of educational gardens as models for students was evidenced, which suggests the importance of teachers and institutions carefully considering which model to offer. Overall, our results support the legitimacy of incorporating gardens to educational centers, particularly for promoting contact with live plants and plant knowledge, and potentially for promoting contact with garden fauna and activities oriented toward learning about it.

FAST VLBI: current status and future plans

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest single-dish radio telescope in the world, and is now being commissioned after the first light in September 2016. Very long baseline interferometry (VLBI) is among the key science topics according to the original design. The FAST VLBI system has been established, and the first VLBI fringe has been successfully obtained. FAST will significantly improve the sensitivity of the existing VLBI networks in the future, and some science projects in need of high sensitivity will benefit from its participation.

The Cryogenic AntiCoincidence Detector for ATHENA X-IFU: The Project Status

The ATHENA observatory is the second large class ESA mission to be launched on 2031 at L2 orbit. One of the two onboard instruments is X-IFU, a TES-based kilo-pixel array able to perform simultaneous high-grade energy spectroscopy (FWHM 2.5 eV@7 keV) and imaging over the 5′ field of view. The X-IFU sensitivity is degraded by primary particle background of both solar and galactic cosmic ray (GCR) origins, and by secondary electrons produced by primaries, interacting with the materials surrounding the detector: These particles cannot be distinguished by the scientific photons, thus degrading the instrument performance. Results from studies regarding the GCR component performed by Geant4 simulations address the necessity to use background reduction techniques to enable the study of several key science topics. This is feasible by combining an active Cryogenic AntiCoincidence detector (CryoAC) and a passive electron shielding to reach the required residual particle background of 0.005 cts/cm2/s/keV inside the 2–10 keV scientific energy band. The CryoAC is a four-pixel detector made of Si-suspended absorbers sensed by a network of IrAu TESes and placed at a distance < 1 mm below the TES array. Here we will provide an overview of the CryoAC program, starting with some details on the background assessment having impacts on the CryoAC design; then, we continue with its design concept including electronics and the Demonstration Model results, to conclude with programmatic aspects.

X-ray Binary Transients in the Magellanic Clouds and the Milky Way

AbstractThe X-ray sky is dominated by luminous galactic sources, variable on time-scales from milliseconds to years. Their eruptive behaviour is now under continuous monitoring by MAXI, Swift, INTEGRAL and other high-energy missions, and representing a superb exemplar of time-domain astronomy. Understanding the astrophysics of such variability requires multi-wavelength follow-up studies from a suite of ground- and space-based facilities. As SALT is a 100% Q-scheduled telescope, one of its key scientific capabilities is related to Target-of-Opportunity (ToO) programmes, and there has been a dedicated SALT Large Programme on Transients in place since 2016, a significant fraction of which has been devoted to the follow-up of X-ray binary transients. This Workshop addressed questions of how such programmes should evolve once the era of MeerKAT and MeerLICHT begins in ∼2018-9 (as well as other huge surveys at optical wavelengths), identifying the range of facilities that would be needed, and the key science topics. There is a clear and growing need for responses to transients to be faster (within minutes if possible), and to be multi-wavelength (particularly in radio and X-ray). Furthermore, extended ongoing coverage of such events (days to weeks for the next ‘V404 Cyg’-type outburst) will be needed for maximum astrophysical return. That would require careful management and coordination of a wide range of ground- and space-based facilities, and optimising coverage against logistical constraints that are often conflicting.

The Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is planned to be the next generation ground based observatory for very high energy (VHE) gamma-ray astronomy. Gamma-rays provide a powerful insight into the non-thermal universe and hopefully a unique probe for new physics. Imaging Cherenkov telescopes have already discovered more than 170 VHE gamma-ray emitters providing plentiful of valuable data and clearly demonstrating the power of this technique. In spite of the impressive results there are indications that the known sources represent only the tip of the iceberg. A major step in sensitivity is needed to increase the number of detected sources, observe short time-scale variability and improve morphological studies of extended sources. An extended energy coverage is advisable to observe far-away extragalactic objects and improve spectral analysis. CTA aims to increase the sensitivity by an order of magnitude compared to current facilities, to extend the accessible gamma-ray energies from a few tens of GeV to a hundred of TeV, and to improve on other parameters like angular and energy resolution. CTA will provide moreover a full sky-coverage by featuring an array of imaging atmospheric Cherenkov telescopes in both hemispheres.This paper presents an overview of the technical design and summarize the current status of the project. CTA prospects for some key science topics like the origin of relativistic cosmic particles, the acceleration mechanisms in extreme environments such as neutron stars and black holes and searches for Dark Matter are discussed.

LOFAR and Radio-Loud AGN

AbstractAt very low frequencies, the new pan-European radio telescope, LOFAR, is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. Operating at frequencies from 15 to 240 MHz, its superb sensitivity, high angular resolution, large field of view and flexible spectroscopic capabilities represent a dramatic improvement over previous facilities at these wavelengths. LOFAR will carry out a broad range of fundamental astrophysical studies in a number of key science topics including the formation and evolution of clusters, galaxies and black holes. In this contribution we describe some of the capabilities of LOFAR and present some recent results from the ongoing imaging efforts. We also discuss the impact of LOFAR on our studies of radio-loud AGN. Our recent study of the evolution of radio-loud AGN as a function of host stellar mass shows a clear increase in the fraction of lower mass galaxies which host radio-loud AGN at 1 &lt; z &lt; 2 while the fraction for higher mass galaxies remains the same. This shows that the upturn in the radio luminosity function is driven by increasing AGN activity among low mass galaxies at higher redshifts. New LOFAR observations will allow us to build statistically large samples at high redshifts to constrain this evolution for the different accretion modes of AGN.

The Solar-B EUV imaging spectrometer and its science goals

The Solar-B mission includes an Extreme-UV Imaging Spectrometer (EIS). It detects photons in the ranges 170–210 and 250–290 Å which include emission lines from several highly ionised species that exist at temperatures log T = 4.7, 5.6, 5.8, 5.9 and 6.0–7.3 K. In this paper, we will describe the design and operation of the instrument and present its performance parameters, e.g., spectral and spatial resolution and sensitivity. Preliminary results of recent calibration measurements will be described. Its role in the Solar-B mission will be illustrated with reference to several key science topics that the EIS is expected to address. The anticipated observing strategy for the first three months of the mission will be outlined.

Task Force on Strategic Research Direction: Basic Science Subgroup key science topics report.

Task Force on Strategic Research Direction: Basic Science Subgroup key science topics report.