Finding counterparts for All-sky X-ray surveys with Nway: a Bayesian algorithm for cross-matching multiple catalogues

We release the AllWISE counterparts and Gaia matches to 106,573 and 17,665 X-ray sources detected in the ROSAT 2RXS and XMMSL2 surveys with |b|>15. These are the brightest X-ray sources in the sky, but their position uncertainties and the sparse multi-wavelength coverage until now rendered the identification of their counterparts a demanding task with uncertain results. New all-sky multi-wavelength surveys of sufficient depth, like AllWISE and Gaia, and a new Bayesian statistics based algorithm, NWAY, allow us, for the first time, to provide reliable counterpart associations. NWAY extends previous distance and sky density based association methods and, using one or more priors (e.g., colors, magnitudes), weights the probability that sources from two or more catalogues are simultaneously associated on the basis of their observable characteristics. Here, counterparts have been determined using a WISE color-magnitude prior. A reference sample of 4524 XMM/Chandra and Swift X-ray sources demonstrates a reliability of ~ 94.7% (2RXS) and 97.4% (XMMSL2). Combining our results with Chandra-COSMOS data, we propose a new separation between stars and AGN in the X-ray/WISE flux-magnitude plane, valid over six orders of magnitude. We also release the NWAY code and its user manual. NWAY was extensively tested with XMM-COSMOS data. Using two different sets of priors, we find an agreement of 96% and 99% with published Likelihood Ratio methods. Our results were achieved faster and without any follow-up visual inspection. With the advent of deep and wide area surveys in X-rays (e.g. SRG/eROSITA, Athena/WFI) and radio (ASKAP/EMU, LOFAR, APERTIF, etc.) NWAY will provide a powerful and reliable counterpart identification tool.Comment: MNRAS, Paper accepted for publication. Updated catalogs are available at www.mpe.mpg.de/XraySurveys/2RXS_XMMSL2 . NWAY available at https://github.com/JohannesBuchner/nwa

Spectral Energy Distribution Mapping of Two Elliptical Galaxies on sub-kpc scales

We use high-resolution Herschel-PACS data of 2 nearby elliptical galaxies, IC1459 & NGC2768 to characterize their dust and stellar content. IC1459 & NGC2768 have an unusually large amount of dust for elliptical galaxies (1-3 x 10^5 Msun), this dust is also not distributed along the stellar content. Using data from GALEX (ultraviolet) to PACS (far-infrared), we analyze the spectral energy distribution (SED) of these galaxies with CIGALEMC as a function of the projected position, binning images in 7.2" pixels. From this analysis, we derive maps of SED parameters, such as the metallicity, the stellar mass, the fraction of young star and the dust mass. The larger amount of dust in FIR maps seems related in our model to a larger fraction of young stars which can reach up to 4% in the dustier area. The young stellar population is fitted as a recent (~ 0.5 Gyr) short burst of star formation for both galaxies. The metallicities, which are fairly large at the center of both galaxies, decrease with the radial distance with fairly steep gradient for elliptical galaxies.Comment: 14 pages, 26 figures, to be published in Ap

The Kuiper Belt Luminosity Function from m(R)=21 to 26

We have performed an ecliptic imaging survey of the Kuiper belt with our deepest and widest field achieving a limiting flux of m(g') = 26.4, with a sky coverage of 3.0 square-degrees. This is the largest coverage of any other Kuiper belt survey to this depth. We detect 72 objects, two of which have been previously observed. We have improved the Bayesian maximum likelihood fitting technique presented in Gladman et al. (1998) to account for calibration and sky density variations and have used this to determine the luminosity function of the Kuiper belt. Combining our detections with previous surveys, we find the luminosity function is well represented by a single power-law with slope alpha = 0.65 +/- 0.05 and an on ecliptic sky density of 1 object per square-degree brighter than m(R)=23.42 +/- 0.13. Assuming constant albedos, this slope suggests a differential size-distribution slope of 4.25 +/- 0.25, which is steeper than the Dohnanyi slope of 3.5 expected if the belt is in a state of collisional equilibrium. We find no evidence for a roll-over or knee in the luminosity function and reject such models brightward of m(R) ~ 24.6.Comment: 50 Pages, 8 Figure

SPIDERS: Selection of spectroscopic targets using AGN candidates detected in all-sky X-ray surveys

SPIDERS (SPectroscopic IDentification of eROSITA Sources) is an SDSS-IV survey running in parallel to the eBOSS cosmology project. SPIDERS will obtain optical spectroscopy for large numbers of X-ray-selected AGN and galaxy cluster members detected in wide area eROSITA, XMM-Newton and ROSAT surveys. We describe the methods used to choose spectroscopic targets for two sub-programmes of SPIDERS: X-ray selected AGN candidates detected in the ROSAT All Sky and the XMM-Newton Slew surveys. We have exploited a Bayesian cross-matching algorithm, guided by priors based on mid-IR colour-magnitude information from the WISE survey, to select the most probable optical counterpart to each X-ray detection. We empirically demonstrate the high fidelity of our counterpart selection method using a reference sample of bright well-localised X-ray sources collated from XMM-Newton, Chandra and Swift-XRT serendipitous catalogues, and also by examining blank-sky locations. We describe the down-selection steps which resulted in the final set of SPIDERS-AGN targets put forward for spectroscopy within the eBOSS/TDSS/SPIDERS survey, and present catalogues of these targets. We also present catalogues of ~12000 ROSAT and ~1500 XMM-Newton Slew survey sources which have existing optical spectroscopy from SDSS-DR12, including the results of our visual inspections. On completion of the SPIDERS program, we expect to have collected homogeneous spectroscopic redshift information over a footprint of ~7500 deg$^2$ for >85 percent of the ROSAT and XMM-Newton Slew survey sources having optical counterparts in the magnitude range 17<r<22.5, producing a large and highly complete sample of bright X-ray-selected AGN suitable for statistical studies of AGN evolution and clustering.Comment: MNRAS, accepte

The Luminosity Function of the Hot and Cold Kuiper belt Populations

Abridged. We have performed an ecliptic survey of the Kuiper belt, with an areal coverage of 8.9 square degrees to a 50% limiting magnitude of r'=24.7, and have detected 88 Kuiper belt objects, roughly half of which received follow-up one to two months after detection. Using this survey data alone, we have measured the luminosity function of the Kuiper belt, thus avoiding any biases that might come from the inclusion of other observations. We have found that the Cold population defined as having inclinations less than 5 degrees has a luminosity function slope alpha=0.82+-0.23, and is different from the Hot population, which has inclinations greater than 5 degrees and a luminosity function slope alpha=0.35+-0.21. As well, we have found that those objects closer than 38 AU have virtually the same luminosity function slope as the Hot population. This result, along with similar findings of past surveys demonstrates that the dynamically cold Kuiper belt objects likely have a steep size distribution, and are unique from all of the excited populations which have much shallower distributions. This suggests that the dynamically excited population underwent a different accretion history and achieved a more evolved state of accretion than the cold population. As well, we discuss the similarities of the Cold and Hot populations with the size distributions of other planetesimal populations. We find that while the Jupiter family comets and the scattered disk exhibit similar size distributions, a power-law extrapolation to small sizes for the scattered disk cannot account for the observed influx of comets. As well, we have found that the Jupiter Trojan and Hot populations cannot have originated from the same parent popuation, a result that is difficult to reconcile with scattering models similar to the NICE model.Comment: Accepted for publication in Icarus. 27 pages, 10 figures, 4 table

The VMC survey - XXVI. Structure of the Small Magellanic Cloud from RR Lyrae stars

We present results from the analysis of 2997 fundamental mode RR Lyrae variables located in the Small Magellanic Cloud (SMC). For these objects, near-infrared time series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and visual light curves from the OGLE IV (Optical Gravitational Lensing Experiment IV) survey are available. In this study, the multi-epoch Ks-band VMC photometry was used for the first time to derive intensity-averaged magnitudes of the SMC RR Lyrae stars. We determined individual distances to the RR Lyrae stars from the near-infrared period–absolute magnitude–metallicity (⁠PMKsZ⁠) relation, which has some advantages in comparison with the visual absolute magnitude–metallicity (MV–[Fe/H]) relation, such as a smaller dependence of the luminosity on interstellar extinction, evolutionary effects and metallicity. The distances we have obtained were used to study the three-dimensional structure of the SMC. The distribution of the SMC RR Lyrae stars is found to be ellipsoidal. The actual line-of-sight depth of the SMC is in the range 1–10 kpc, with an average depth of 4.3 ± 1.0 kpc. We found that RR Lyrae stars in the eastern part of the SMC are affected by interactions of the Magellanic Clouds. However, we do not see a clear bimodality observed for red clump stars, in the distribution of RR Lyrae star

Fermi and intramode relaxation phenomena in CO2lasers

Using a 1 ns pulse from a short-pulse CO2laser system, the evolution of the gain in a TEA system was studied during and after amplification. This resulted in a very direct observation of a few relaxation processes. We estimated the effective intramode relaxation rate constant to be larger than6 times 10^{6}torr-1/s. The Fermi relaxation time constant was found to be 30 ± 7 ns at 760 torr. We conclude that for nanosecond pulse amplification, intramode relaxation cannot be neglected

The Affordability Index: A New Tool for Measuring the True Affordability of a Housing Choice

This brief describes a new information tool developed by the Urban Markets Initiative to quantify, for the first time, the impact of transportation costs on the affordability of housing choices. This brief explains the background, creation, and purpose of this new tool. The first section provides a project overview and a short summary of the method used to create the Affordability Index. The next section highlights the results from testing the index in a seven-county area in and around Minneapolis-St. Paul, MN. To demonstrate the usefulness of this tool at a neighborhood level, the third section projects the effect of transportation and housing choices on three hypothetical low- and moderate-income families in each of four different neighborhoods in the Twin Cities. The brief concludes with suggested policy recommendations and applications of the new tool for various actors in the housing market, and for regulators, planners, and funders in the transportation and land use arenas at all levels of government. The Housing and Transportation Affordability Index is a groundbreaking innovation because it prices the trade-offs that households make between housing and transportation costs and the savings that derive from living in communities that are near shopping, schools, and work, and that boast a transit-rich environment. Built using data sets that are available for every transit-served community in the nation, the tool can be applied in neighborhoods in more than 42 cities in the United States. It provides consumers, policymakers, lenders, and investors with the information needed to make better decisions about which neighborhoods are truly affordable, and illuminate the implications of their policy and investment choices

Keterampilan Berfikir Kritis Pada Pembelajaran IPA Menggunakan Model Pembelajaran Radec di Sekolah Dasar : Systematic Literature Review

Abstract:  The RADEC learning model is an alternative model that can be used by teachers in improving critical thinking skills. The RADEC learning model has the same syntax as the model name: Read, Answer, Discuss, Explain, and Create (RADEC). In this study, the researcher aimed to describe critical thinking skills in science learning using the RADEC learning model in elementary schools. This research method is using a systematic literature review method. In the research, the researcher carried out several stages, namely the identification stage, the selection stage, the verification stage, and then,e combination stage and included. The results showed that the articles obtained by the researchers were 10 articles that matched the research theme. The articles selected and deemed relevant to this research consist of articles published in 2020 which amounted to two articles, in 2021 which amounted to 3 articles and in 2022 which amounted to five articles. Critical thinking skills in science learning can be Created through the stages of RADEC learning. These stages are the Read, Answer, Discuss, Explain and Create stages. The researcher divides the Discussion based on the themes. The themes are (1) RADEC the learning model, (2) RADEC the learning model in science lelearningnd  (3) RADEC learning model in improving critical thinking skills.Abstrak: Model pembelajaran RADEC merupakan salah satu alternatif model yang dapat digunakan oleh guru dalam meningkatkan keterampilan berfikir kritis. Model pembelajaran RADEC memiliki sintaks yang sama dengan nama model yaitu Read, Answer, Discuss, Explain, and Create (RADEC). Pada penelitian ini, peneliti memiliki tujuan untuk mendeskripsikan mengenai keterampilan berfikir kritis pada pembelajaran IPA menggunakan model pembelajaran RADEC di sekolah dasar. Metode penelitian ini yaitu menggunakan Metode Systematic literature review. Pada penelitian peneliti melakukan beberapa tahapan yaitu tahap identifikasi, tahap seleksi, tahap verifikasi dan tahap kombinasi serta menyimpulkan. Hasil penelitian menunjukan bahwa artikel yang diperoleh oleh peneliti adalah 10 artikel yang sesuai dengan tema penelitian. Artikel yang dipilih dan dianggap relevan dengan penelitian ini terdiri dari artikel yang terbit pada tahun 2020 yang berjumlah 2 artikel, tahun 2021 yang berjumlah 3 artikel dan tahun 2022 yang berjumlah 5 artikel. Keterampilan berfikir kritis pada pembelajaran IPA dapat tercipta melalui tahapan-tahapan pembelajaran RADEC. Tahapan tersebut yaitu tahap Read, Answer, Discuss, Explain dan Create. Peneliti membagi pembahasan berdasarkan tema-tema. Tema-tema tersebut yaitu (1) Model pembelajaran RADEC, (2) Model Pembelajaran RADEC dalam pembelajaran IPA, (3) model pembelajaran RADEC dalam meningkatkan keterampilan berfikir kriti