Quasars and their host galaxies

This review attempts to describe developments in the fields of quasar and quasar host galaxies in the past five. In this time period, the Sloan and 2dF quasar surveys have added several tens of thousands of quasars, with Sloan quasars being found to z>6. Obscured, or partially obscured quasars have begun to be found in significant numbers. Black hole mass estimates for quasars, and our confidence in them, have improved significantly, allowing a start on relating quasar properties such as radio jet power to fundamental parameters of the quasar such as black hole mass and accretion rate. Quasar host galaxy studies have allowed us to find and characterize the host galaxies of quasars to z>2. Despite these developments, many questions remain unresolved, in particular the origin of the close relationship between black hole mass and galaxy bulge mass/velocity dispersion seen in local galaxies.Comment: Review article, to appear in Astrophysics Update

Young and Intermediate-age Distance Indicators

Distance measurements beyond geometrical and semi-geometrical methods, rely mainly on standard candles. As the name suggests, these objects have known luminosities by virtue of their intrinsic proprieties and play a major role in our understanding of modern cosmology. The main caveats associated with standard candles are their absolute calibration, contamination of the sample from other sources and systematic uncertainties. The absolute calibration mainly depends on their chemical composition and age. To understand the impact of these effects on the distance scale, it is essential to develop methods based on different sample of standard candles. Here we review the fundamental properties of young and intermediate-age distance indicators such as Cepheids, Mira variables and Red Clump stars and the recent developments in their application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in Space Science Reviews (Chapter 3 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

A critical reconceptualization of faculty readiness for online teaching

© 2020 Open and Distance Learning Association of Australia, Inc. Online courses are mainstream throughout higher education. This pattern has been accelerated, temporarily or permanently, due to the coronavirus pandemic (Allen & Seaman, 2016; Arum & Stevens, 2020; Garrison, 2011). Tenure-track and contingent faculty’s willingness to teach online serves students, but little research critiques the forces that produce and constrain faculty’s efforts. Even the most current discussions of faculty readiness lack a strong grounding in criticality. Without such a critical orientation, the power and equity issues involved in the higher education marketplace of online teaching cannot be adequately examined. This critical integrated literature review of 44 studies documents themes of the affective dimensions and identity disruption surrounding faculty’s readiness to teach online and explores their professional vulnerability. Structural and cultural forces that produce and constrain faculty’s experiences transitioning to online teaching emerged from the analysis. This conceptualization of faculty readiness provides a foundation upon which to theorize faculty’s equitable experiences of online teaching

Faculty readiness for online crisis teaching: transitioning to online teaching during the COVID-19 pandemic

© 2020 Association for Teacher Education in Europe. This mixed-methods study was designed to measure and elaborate constructs of faculty online readiness from pre- COVID-19 pandemic literature. Bringing together the validation of a scale to measure these constructs and insights from a focus group, findings suggest that the negative connotations of risk-taking and making mistakes while learning to teach online seem to have been mitigated by a combination of affective factors such as humility, empathy, and even optimism. Teacher educators explained that transitioning online in a context of a crisis contorts normal longitudinal perceptions of preparation and readiness. This new sense of temporality was connected to unexpected benefits of bringing them into partnership with their students. However, quantitative and qualitative results are interpreted to show that assessing students’ equitable access to online learning and managing the demands of scholarship and university-based and academic community service duties are areas in need of attention from professional development designers and policy makers

XMM-Newton observations of two hyperluminous IRAS galaxies: Compton-thick quasars with obscuring starbursts

We present XMM-Newton observations of two hyperluminous IRAS galaxies (L_Bol>1E13 L_sun), neither of which was previously detected by ROSAT. Published models of the infrared SEDs imply that a starburst and obscured quasar contribute equally to the power of each source. IRAS F12514+1027 (z=0.30) is detected in 18.6 ks with 130 EPIC-pn counts over 0.2-12 keV. The soft X-ray spectrum exhibits thermal emission from the starburst, with T=0.3 keV and L(0.5-2.0keV)=2.1E42 erg/s. With its Fe K-edge, the flat continuum above 2 keV is interpreted as cold reflection from a hidden AGN with an intrinsic L(2-10keV) of at least 1.8E44 erg/s. Comparison with the infrared power requires that the X-ray reflector subtend ~2pi/5 sr at the central engine. IRAS F00235+1024 (z=0.575) is not detected by the EPIC-pn in 15.9 ks; the limits imply that the starburst is X-ray weak, and (for the AGN) that any hard X-ray reflector subtend <2pi/5 sr. The direct lines of sight to the AGN in both objects are Compton-thick, and the presence of a reflection component in F12514+1027, but not in F00235+1024, suggests that the AGN in the latter object is more completely obscured. This is consistent with their Seyfert-2 and starburst optical spectra, respectively.Comment: 5 pages, 3 figures; to be published in MNRA

Infrared Photometry of GEO Spacecraft with WISE

NASA launched the Wide-field Infrared Survey Explorer (WISE) into orbit on December 2009 with a mission to scan the entire sky in the infrared in four wavelength bands of 3.4, 4.6, 12, and 22 microns. WISE acquired data in the four bands for 10 months until the solid hydrogen cryogen was depleted and then proceeded to operate in the two short er wavelength bands for an additional four months in a Post-Cryo phase. In its trove of data, WISE captured many streaks that were artificial satellites in orbit around Earth. We have examined a subset of equatorial WISE images with |declination | 30 degrees in order to minimize contamination of the satellite streaks by stars in the galactic plane. At least one streak of the length appropriate for a GEO station-keeping satellite appears in over 10% of these images. In bands 1 through 3 (for images 1016x1016 in size), the streaks are approximately 100 pixels in length, and in band 4 (for images 508x508 in size), the streaks are approximately 50 pixels in length. Most, but not all, of these spacecraft appear in all 4 wavelength bands. Since WISE is in a Sun-synchronous orbit pointed approximately radially away from the Earth at all times, all observations of GEO objects were obtained at a solar phase angle of approximately 90 degrees. We report on the color distributions of these detections and interpret the colors and compare the spacecraft colors with colors of other astronomical objects such as stars, galaxies, and asteroids that have appeared in previously published works on WISE data

Limits on the X-ray emission from several hyperluminous IRAS galaxies

We report long, pointed ROSAT HRI observations of the hyperluminous galaxies IRAS F00235+1024, F12514+1027, F14481+4454 and F14537+1950. Two of them are optically classified as Seyfert-like. No X-ray sources are detected at the positions of any of the objects, with a mean upper limit L(X)/L(Bol) of 2.3 times 10^-4. This indicates that any active nuclei are either atypically weak at X-ray wavelengths or obscured by column densities N(H)>10^23 cm^-2. They differ markedly from `ordinary' Seyfert 2 galaxies, bearing a closer resemblance in the soft X-ray band to composite Seyfert 2 galaxies or to some types of starburst.Comment: 4 pages, 1 figure. Accepted for publication in MNRA

Distinguishing Active Box-Wing and Cylindrical Geostationary Satellites using IR Photometry with NASA’s WISE Spacecraft

Over 860 observations of 245 box-wing (BW) and 18 cylindrical (C) active geostationary satellites (GEOsats) have been extracted from the thousands of resident space objects (RSOs) serendipitously detected by NASA’s Wide-field Infrared Survey Explorer (WISE). In 2010, WISE performed an all-sky infrared (IR) survey at 3.4, 4.6, 12, and 22 microns simultaneously from low Earth orbit (LEO). For GEOsats, these wavelengths are in the reflective and thermal IR regimes, and all observations were obtained near quadrature. From our unresolved IR photometry of GEOsats, we report and discuss a distinguishing characteristic between BW and C GEOsats using a unique combination of IR fluxes, along with generalizations of GEOsat photometry and colors as a whole based on our large sample size

WISE thermal IR observations of IDCSP satellites

The Initial Defense Communications Satellite Program (IDCSP) comprised a series of 27 communications satellites launched into sub-geosynchronous orbit between 1966 and 1968. They are some of the oldest satellites in the geosynchronous (GEO) regime. These were 0.86-m diameter 26-sided polygon spin-stabilized satellites covered with solar panels. There were no batteries or attitude control systems. The population was largely but not entirely identical. We report on observations of these satellites with the Wide-field Infrared Survey Explorer (WISE) satellite which conducted a four-band infra-red survey of the entire sky between January and October 2010. In the WISE images are observations of every one of thesesatellites. They are marginally or not detected in the two shorter wavelength WISE bands (3.4 and 4.6 microns) where the flux is dominated by reflected sunlight. This result is not surprising, since these are some of the faintest objects at visible wavelengths in the public catalog, and the WISE observations were obtained at a phase angle of close to 90 degrees. The IDCSPs are better detected in the two longer wavelength WISE bands (12 and 22 microns) where the flux is dominated by thermal emission fromthe satellite. At 12 microns the magnitude distribution is very sharply peaked near 6.3. We report on the thermal IR magnitudes and colors of these inactive satellites and compare them with thermal IR magnitudes and colors of other objects in the GEO regime

Asteroid diameters and albedos from neowise reactivation mission years six and seven

We present diameters and albedos computed for the near-Earth and main belt asteroids (MBAs) observed by the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft during the sixth and seventh years of its Reactivation mission. These diameters and albedos are calculated from fitting thermal models to NEOWISE observations of 199 near-Earth objects (NEOs) and 5851 MBAs detected during the sixth year of the survey and 175 NEOs and 5861 MBAs from the seventh year. Comparisons of the NEO diameters derived from Reactivation data with those derived from the WISE cryogenic mission data show a ∼30% relative uncertainty. This larger uncertainty compared to data from the cryogenic mission is due to the need to assume a beaming parameter for the fits to the shorter-wavelength data that the Reactivation mission is limited to. We also present an analysis of the orbital parameters of the MBAs that have been discovered by NEOWISE during Reactivation, finding that these objects tend to be on orbits that result in their perihelia being far from the ecliptic, and thus missed by other surveys. To date, the NEOWISE Reactivation survey has provided thermal fits of 1415 unique NEOs. Including the mission phases before spacecraft hibernation increases the count of unique NEOs characterized to 1845 from WISE's launch to the present. © 2021. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]