Context. Massive black holes (MBHs) are typically hosted in the centres of massive galaxies but they appear to become rarer in lower mass galaxies, where nuclear star clusters (NSCs) frequently appear instead. The transition region, where both an MBH and NSC can co-exist, has been poorly studied to date and only a few dozen galaxies are known to host them. One avenue for detecting new galaxies with both an MBH and NSC is to look for accretion signatures of MBHs. Aims. Here, we use new SRG/eROSITA all-sky survey eRASS:4 data to search for X-ray signatures of accreting MBHs in NSCs, while also investigating their combined occupation fraction. Methods. We collected more than 200 galaxies containing an NSC, spanning multiple orders in terms of galaxy stellar mass and morphological type, within the footprint of the German eROSITA Consortium survey. We determined the expected X-ray contamination from binary stellar systems using the galaxy stellar mass and star formation rate as estimated from far-ultraviolet and mid-infrared emission. Results. We find significant detections for 18 galaxies (similar to 8.3%), including one ultra-luminous X-ray source; however, only three galaxies (NGC2903, 4212, and 4639) have X-ray luminosities that are higher than the expected value from X-ray binaries, indicative of the presence of an MBH. In addition, the X-ray luminosity of six galaxies (NGC2903, 3384, 4321, 4365, 4639, and 4701) differs from previous studies and could indicate the presence of a variable active galactic nucleus. For NGC4701 specifically, we find a variation of X-ray flux within the eRASS:4 data set. Stacking X-ray non-detected galaxies in the dwarf regime (M-star(gal) <= 10(9) M-circle dot) results in luminosity upper limits of a few times 10(38) erg s(-1). The combined occupation fraction of accreting MBHs and NSCs becomes non-zero for galaxy masses above similar to 10(7.5) M-circle dot and this result is slightly elevated as compared to the literature data. Conclusions. Our data extend, for the first time, towards the dwarf elliptical galaxy regime and identify promising MBH candidates for higher resolution follow-up observations. At most galaxy masses (and with the exception of three cases), the X-ray constraints are consistent with the expected emission from binary systems or an Eddington fraction of at most 0.01%, assuming a black holes mass of 10(6.5) M-circle dot. This work confirms the known complexities in similar-type of studies, while providing the appealing alternative of using X-ray survey data of in-depth observations of individual targets with higher resolution instruments.

The eROSITA will deliver an unprecedented volume of X-ray survey observations, 20-30 times more sensitive than ROSAT in the soft band (0.5-2 keV) and for the first time imaging in the hard band (2-10 keV) including galaxy clusters and groups along with obscured and unobscured AGNs. This calls for a powerful theoretical effort to control the systematics and biases that may affect the data analysis. We investigate the detection technique and selection effects in the galaxy group and AGN populations of a mock eROSITA survey at the depth of eRASS:4. We create a $30\times 30$ deg$^{2}$ mock observation based on the cosmological hydrodynamical simulation Magneticum Pathfinder within z=0-0.2. We combine a physical background extracted from the real eFEDS background analysis with realistic simulations of X-ray emission for the hot gas, AGNs and X-ray binaries. We apply a detection procedure equivalent to the reduction done on eRASS data and evaluate the completeness and contamination to reconstruct the luminosity functions of the extended and point sources in the catalogue. We assess the completeness of extended detections as a function of the input X-ray flux and halo. We achieve full recovery of the brightest (most massive) clusters and AGNs. However, a significant fraction of galaxy groups remains undetected. Examining the gas properties between the detected and undetected galaxy groups at fixed halo mass, we observe that the detected population exhibits, on average, higher X-ray brightness compared to the undetected ones. Moreover, we find that X-ray luminosity primarily correlates with the hot gas fraction, rather than temperature or metallicity. Our simulation suggests the presence of a systematic selection effect in current surveys, resulting in X-ray survey catalogues predominantly composed of the lowest-entropy, gas-richest, and highest surface brightness halos on galaxy group scales.

Aims. Understanding how the properties of galaxies relate to the properties of the hot circum-galactic medium (CGM) around them can constrain galaxy evolution models. We aim to measure the scaling relations between the X-ray luminosity of the hot CGM and the fundamental properties (stellar mass and halo mass) of a galaxy. Methods. We measured the X-ray luminosity of the hot CGM based on the surface brightness profiles of central galaxy samples measured from Spectrum Roentgen Gamma (SRG)/eROSITA all-sky survey data. We related the X-ray luminosity to the galaxies' stellar and halo mass, and we compared the observed relations to the self-similar model and intrinsic (i.e., not forward-modeled) output of the IllustrisTNG, EAGLE, and SIMBA simulations. Results. The average hot CGM X-ray luminosity (L-X,L- CGM) correlates with the galaxy's stellar mass (M-*). It increases from (1.6 +/- 2.1) x 10(39) erg s(-1) to (3.4 +/- 0.3) x 10(41) erg s(-1), when log(M-*) increases from 10.0 to 11.5. A power law describes the correlation as log(L-X,L- CGM) = (2.4 +/- 0.1)xlog(M-*)+(14.6 +/- 1.5). The hot CGM X-ray luminosity as a function of halo mass is measured within log(M-500c) = 11.3 - 13.7, extending our knowledge of the scaling relation by more than two orders of magnitude. L-X,L- CGM increases with M-500c from (3.0 +/- 1.6) x 10(39) erg s(-1) at log(M-500c) = 11.3 to (1.3 +/- 0.1) x 10(42) erg s(-1) at log(M-500c) = 13.7. The relation follows a power law of log(L-X,L- CGM) = (1.32 +/- 0.05)xlog(M-500c)+(24.1 +/- 0.7). Our observations highlight the necessity of non-gravitational processes at the galaxy group scale while suggesting these processes are sub-dominant at the galaxy scale. We show that the outputs of current cosmological galaxy simulations generally align with the observational results uncovered here but with possibly important deviations in selected mass ranges. Conclusions. We explore, at the low mass end, the average scaling relations between the CGM X-ray luminosity and the galaxy's stellar mass or halo mass, which constitutes a new benchmark for galaxy evolution models and feedback processes.

The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying the sky in December 2019, with the aim of producing all-sky X-ray source lists and sky maps of an unprecedented depth. Here we present catalogues of both point-like and extended sources using the data acquired in the first six months of survey operations (eRASS1; completed June 2020) over the half sky whose proprietary data rights lie with the German eROSITA Consortium. We describe the observation process, the data analysis pipelines, and the characteristics of the X-ray sources. With nearly 930 000 entries detected in the most sensitive 0.2–2.3 keV energy range, the eRASS1 main catalogue presented here increases the number of known X-ray sources in the published literature by more than 60%, and provides a comprehensive inventory of all classes of X-ray celestial objects, covering a wide range of physical processes. A smaller catalogue of 5466 sources detected in the less sensitive but harder 2.3–5 keV band is the result of the first true imaging survey of the entire sky above 2 keV. We present methods to identify and flag potential spurious sources in the catalogues, which we applied for this work, and we tested and validated the astrometric accuracy via cross-comparison with other X-ray and multi-wavelength catalogues. We show that the number counts of X-ray sources in eRASSl are consistent with those derived over narrower fields by past X-ray surveys of a similar depth, and we explore the number counts variation as a function of the location in the sky. Adopting a uniform all-sky flux limit (at 50% completeness) ofF05–2 keV> 5 × 10−14erg s−1cm−2, we estimate that the eROSITA all-sky survey resolves into individual sources about 20% of the cosmic X-ray background in the 1–2 keV range. The catalogues presented here form part of the first data release (DR1) of the SRG/eROSITA all-sky survey. Beyond the X-ray catalogues, DR1 contains all detected and calibrated event files, source products (light curves and spectra), and all-sky maps. Illustrative examples of these are provided.

With the increasing significance of compilers in software development, identifying optimization bugs and enhancing their performance has become a significant challenge. In recent years, many studies have targeted only specific analyses to identify missed optimizations (e.g., in data flow analyses). While there have been some general approaches, most rely on differential testing between different compilers, which makes it difficult to identify optimization bugs that are common to multiple compilers. This paper tackles these challenges by introducing an effective and general approach called MOD. MOD works by using a manually-curated mapping between optimizations, ensuring that code should be consistently optimized: if one optimization triggers but the other does not, that indicates a bug in either of the two optimizations. We implemented MOD as a tool to detect missed optimizations in the available expressions of the LLVM. Experimental results show that MOD can report 20 correct alerts in one hour of detection of random test programs.

We introduce the New-ANGELS program, an XMM-Newton survey of a similar to 7.2 deg2 area around M31, which aims to study the X-ray populations in the M31 disk and the X-ray-emitting hot gas in the inner halo of M31 up to 30 kpc. In this first paper, we report the catalog of 4506 detected X-ray sources and attempt to cross-identify or roughly classify them. We identify 352 single stars in the foreground, 35 globular clusters, and 27 supernova remnants associated with M31, as well as 62 active galactic nuclei, 59 galaxies, and one galaxy cluster in the background. We uniquely classify 236 foreground stars and 17 supersoft sources based on their X-ray colors. X-ray binaries (83 low-mass and one high-mass) are classified based on their X-ray colors and X-ray variabilities. The remaining X-ray sources either have too low signal-to-noise ratios to calculate their X-ray colors or do not have a unique classification, so are regarded as unclassified. The X-ray source catalog is published online. Studies of the X-ray source populations and the contribution of X-ray sources in the unresolved X-ray emissions based on this catalog will be published in companion papers.

The prevalence of GPS positioning software has led to the generation of massive trajectory data, so it is necessary to take measures to compress the data. This paper proposes an efficient trajectory simplification algorithm based on Essential Inflection Point Extraction (EIPE). EIPE algorithm adopts synchronous Euclidean distance and direction angle deviation to preserve the temporal-spatial information while compressing the trajectories. However, considering the direction angle deviation will improve the compression rate for trajectories with high randomness in direction. To address this issue, we set a range threshold for the EIPE algorithm to extract essential inflection points from trajectories. The evaluation results on two real-life datasets indicate that our algorithm can improve compression efficiency and achieve satisfactory performance on both average direction angle deviation error and running time.

Aims. The circumgalactic medium (CGM) plays an important role in galaxy evolution as the main interface between the star-forming body of galaxies and the surrounding cosmic network of in- and out-flowing matter. In this work, we aim to characterize the hot phase of the CGM in a large sample of galaxies using recent soft-X-ray observations made by SRG /eROSITA. Methods. We stack X-ray events from the ‘eROSITA Final Equatorial Depth Survey’ (eFEDS) around central galaxies in the 9hr field of the ‘GAlaxy and Mass Assembly’ (GAMA) survey to construct radially projected X-ray luminosity profiles in the 0.5–2 keV rest frame energy band as a function of their stellar mass and specific star formation rate. We consider samples of quiescent (star-forming) galaxies in the stellar mass range 2 × 10 10 –10 12 M ⊙ (3 × 10 9 –6 × 10 11 M ⊙ ). Results. For quiescent galaxies, the X-ray profiles are clearly extended throughout the available mass range; however, the measured profile is likely biased high because of projection effects, as these galaxies tend to live in dense and hot environments. For the most massive star-forming samples (≥10 11 M ⊙ ), there is a hint of detection of extended emission. On the other hand, for star-forming galaxies with < 10 11 M ⊙ the X-ray stacked profiles are compatible with unresolved sources and are consistent with the expected emission from faint active galactic nuclei (AGN) and X-ray binaries. We measure for the first time the mean relation between average X-ray luminosity and stellar mass separately for quiescent and star-forming galaxies. We find that the relation is different for the two galaxy populations: high-mass (≥10 11 M ⊙ ) star-forming or quiescent galaxies follow the expected scaling of virialized hot haloes, while lower mass star-forming galaxies show a less prominent luminosity and a weaker dependence on stellar mass consistent with empirical models of the population of weak AGN. When comparing our results with state-of-the-art numerical simulations (IllustrisTNG and EAGLE), we find overall consistency on the average emission on large (> 80 kpc) scales at masses ≥10 11 M ⊙ , but disagreement on the small scales, where brighter-than-observed compact cores are predicted. The simulations also do not predict the clear differentiation that we observe between quiescent and star-forming galaxies in our samples. Conclusions. This is a stepping stone towards a more profound understanding of the hot phase of the CGM, which holds a key role in the regulation of star formation. Future analysis using eROSITA all-sky survey data, combined with future generation galaxy evolution surveys, shall provide much enhanced quantitative measurements and mapping of the CGM and its hot phase(s).

Recently, gamma-ray halos of a few degree extension have been detected around two middle-aged pulsars, namely, Geminga and PSR B0656+14, by the High Altitude Water Cherenkov observatory (HAWC). The gamma-ray radiation arises from relativistic electrons that escape the pulsar wind nebula and diffuse in the surrounding medium. The diffusion coefficient is found to be significantly lower than the average value in the Galactic disk. If so, given a typical transverse velocity of 300–500 km s−1 for a pulsar, its displacement could be important in shaping the morphology of its gamma-ray halos. Motivated by this, we study the morphology of pulsar halos considering the proper motion of pulsar. We define three evolutionary phases of the pulsar halo to categorize its morphological features. The morphology of pulsar halos below 10 TeV is double peaked or single peaked with an extended tail, which depends on the electron injection history. Above 10 TeV, the morphology of pulsar halos is nearly spherical, due to the short cooling timescale (<50 kyr) for tens of teraelectronvolt electrons. We also quantitatively evaluate the separation between the pulsar and the center of the gamma-ray halo, as well as the influence of different assumptions on the pulsar characteristics and the injected electrons. Our results suggest that the separation between the center of the gamma-ray halo above 10 TeV and the associated pulsar is usually too small to be observable by HAWC or the Large High Altitude Air Shower Observatory. Hence, our results provide a useful approach to constrain the origin of extended sources at very high energies.

Aims. The circumgalactic medium (CGM) plays an important role in galaxy evolution as the main interface between the star-forming body of galaxies and the surrounding cosmic network of in- and out-flowing matter. In this work, we aim to characterize the hot phase of the CGM in a large sample of galaxies using recent soft-X-ray observations made by SRG/eROSITA. Methods. We stack X-ray events from the 'eROSITA Final Equatorial Depth Survey' (eFEDS) around central galaxies in the 9hr field of the 'GAlaxy and Mass Assembly' (GAMA) survey to construct radially projected X-ray luminosity profiles in the 0.5-2 keV rest frame energy band as a function of their stellar mass and specific star formation rate. We consider samples of quiescent (star-forming) galaxies in the stellar mass range 2 x 10(10)-10(12) M-circle dot (3 x 10(9)-6 x 10(11) M-circle dot). Results. For quiescent galaxies, the X-ray profiles are clearly extended throughout the available mass range; however, the measured profile is likely biased high because of projection effects, as these galaxies tend to live in dense and hot environments. For the most massive star-forming samples (>= 10(11) M-circle dot), there is a hint of detection of extended emission. On the other hand, for star-forming galaxies with <10(11) M-circle dot the X-ray stacked profiles are compatible with unresolved sources and are consistent with the expected emission from faint active galactic nuclei (AGN) and X-ray binaries. We measure for the first time the mean relation between average X-ray luminosity and stellar mass separately for quiescent and star-forming galaxies. We find that the relation is different for the two galaxy populations: high-mass (>10(11) M-circle dot) star-forming or quiescent galaxies follow the expected scaling of virialized hot haloes, while lower mass star-forming galaxies show a less prominent luminosity and a weaker dependence on stellar mass consistent with empirical models of the population of weak AGN. When comparing our results with state-of-the-art numerical simulations (IllustrisTNG and EAGLE), we find overall consistency on the average emission on large (>80 kpc) scales at masses >= 10(11) M-circle dot, but disagreement on the small scales, where brighter-than-observed compact cores are predicted. The simulations also do not predict the clear differentiation that we observe between quiescent and star-forming galaxies in our samples. Conclusions. This is a stepping stone towards a more profound understanding of the hot phase of the CGM, which holds a key role in the regulation of star formation. Future analysis using eROSITA all-sky survey data, combined with future generation galaxy evolution surveys, shall provide much enhanced quantitative measurements and mapping of the CGM and its hot phase(s).

The metaphor can serve as an effective tool in science communication. This article studies the posts and comments of the Weibo account of Jade Rabbit of the Moon Rover, which construes the rover metaphorically as an anthropomorphized rabbit. This study explores the motivation and effect of this metaphor. Conceptual motivation can be found in the similarities between the rover and the anthropomorphized rabbit. Communicative motivation lies in its enhanced effectiveness in promoting science. The metaphor has been readily accepted by Weibo users who have displayed emotional reactions to its metaphorical construal, acquired astronomical knowledge, and determined to embark on scientific careers.

It has been suggested that a huge amount of baryon resides in the circumgalactic medium (CGM) extending out to the virial radii of galaxies. In this work we attempt to measure the baryon mass in the CGM with a novel method based on the gamma-ray observations of the extended halo of the Andromeda galaxy Messier 31 (M31). Since cosmic-ray particles generated inside the galaxy will eventually escape to the CGM, they will produce gamma-ray emission via the proton-proton collision with the CGM and produce gamma-rays. Different from some traditional measurements that are sensitive only to certain metallic ions in specific temperature range, the hadronic gamma-ray flux is sensitive to baryonic gases in all phases and does not rely on the metallicity in the halo, hence the measured gamma-ray flux from the galaxy's halo can be used to constrain the mass of the CGM. By dealing with the cosmic-ray transport in the halo and calculating the hadronic gamma-ray intensity, we find that the total baryon mass contained within the virial radius is less than (1.4-5) x 10(10) M (circle dot) according to the gamma-ray intensity obtained with a model-dependent analysis. It implies that the CGM of Andromeda galaxy may not account for more than 30% of the missing baryons, but the result is subject to uncertainties from the gamma-ray intensity upper limit, diffusion coefficient of the cosmic-rays in the halo, as well as the stellar mass and dark matter halo mass of the galaxy. This method will become more constraining provided better understandings on these issues and more sensitive gamma-ray telescopes in the future.

A kinetic impact occurs when an asteroid is moving. The impact may be caused by other small celestial body or an artificial object. Ejecta is produced from an impact. Dynamics of ejecta near a binary system which contains an ellipsoid and a sphere is analyzed. A phase diagram which comes from numerical simulation is shown in this work. The phase diagram shows a clear structure. Some special trajectories are also shown, which indicates a potential source of asteroid orbiting objects.

莺歌海盆地中央底辟带中深层高温高压领域勘探潜力巨大,但受热流体、裂隙、浅层气屏蔽等多因素影响,该领域的地震资料出现了大片模糊区,模糊区成像问题严重制约了该领域勘探获得突破.为解决中央底辟带中深层模糊区成像问题,系统分析了莺歌海盆地底辟结构特征,认为该地区底辟构造具有下部泥底辟和上部流体底辟的双元结构;基于底辟模糊区本质认识,开展了地震模糊区成因机理研究,划分了模糊区地震资料干扰波类型,分析了热流体、裂隙、浅层气屏蔽等因素对模糊区成像的影响及贡献,明确了影响模糊区成像的主控因素,提出了改善地震成像的具体对策,为后续地震资料采集及处理提供了指导依据,对推动这一领域勘探具有重要意义.

It has been found that there is a quasi-linear scaling relationship between the gamma-ray luminosity in GeV energies and the total infrared luminosity of star-forming galaxies, i.e., L-gamma alpha L-IR(alpha) with alpha similar or equal to 1. However, the origin of this linear slope is not well understood. Although extreme starburst galaxies can be regarded as calorimeters for hadronic cosmic-ray interaction and thus a quasi-linear scaling may hold, it may not be the case for low star formation rate (SFR) galaxies, as the majority of cosmic rays in these galaxies are expected to escape. We calculate the gamma-ray production efficiency in star-forming galaxies by considering realistic galaxy properties, such as the gas density and galactic wind velocity in star-forming galaxies. We find that the slope for the relation between gamma-ray luminosity and the infrared luminosity gets steeper for low infrared luminosity galaxies, i.e., alpha -> 1.6, due to increasingly lower efficiency for the production of gamma-ray emission. We further find that the measured data of the gamma-ray luminosity is compatible with such a steepening. The steepening in the slope suggests that cosmic-ray escape is very important in low-SFR galaxies.