Close Pairs Research Articles

H i 21 cm Extended Structures to the Northeast and Southwest of NGC 5595: VLA Observations of the Disk Galaxy Pair NGC 5595 and NGC 5597

We report VLA B-configuration observations of the H i 21 cm line on the close disk galaxy pair NGC 5595 and NGC 5597. At the angular resolution of the observations, ∼7.″1 × 4.″2, while most of the H i 21 cm in NGC 5595 and NGC 5597 has the same extent as the optical disk, we have detected for the first time extended structures (streamers) to the northeast (NE) and southwest (SW) of NGC 5595 with no counterparts in blue, red optical (continuum), 20 cm radio continuum, or Hα spectral line emission. One structure is extended by ∼45″ to the NE with blueshifted velocities, and the other is extended by ∼20″ to the SW with redshifted velocities with respect to the systemic velocity. No H i 21 cm emission is detected from the innermost central (nuclear) regions of either galaxy. Lower angular resolution H i 21 cm imaging indicates the nonexistence of any intergalactic hydrogen atomic H i 21 cm gas as tails or bridges between the two galaxies. Our new 20 cm radio continuum emission image of NGC 5597 shows a strong unresolved elongated structure in the central region, in the NE–SW direction, very similar to the spatial location of the innermost Hα spectral line emission. There is no 20 cm continuum emission from its northern spiral arm. In NGC 5595, the 20 cm radio continuum image shows no continuum emission from the NE or SW extended structures with H i 21 cm emission.

Gender bias perpetuation and mitigation in AI technologies: challenges and opportunities

AbstractAcross the world, artificial intelligence (AI) technologies are being more widely employed in public sector decision-making and processes as a supposedly neutral and an efficient method for optimizing delivery of services. However, the deployment of these technologies has also prompted investigation into the potentially unanticipated consequences of their introduction, to both positive and negative ends. This paper chooses to focus specifically on the relationship between gender bias and AI, exploring claims of the neutrality of such technologies and how its understanding of bias could influence policy and outcomes. Building on a rich seam of literature from both technological and sociological fields, this article constructs an original framework through which to analyse both the perpetuation and mitigation of gender biases, choosing to categorize AI technologies based on whether their input is text or images. Through the close analysis and pairing of four case studies, the paper thus unites two often disparate approaches to the investigation of bias in technology, revealing the large and varied potential for AI to echo and even amplify existing human bias, while acknowledging the important role AI itself can play in reducing or reversing these effects. The conclusion calls for further collaboration between scholars from the worlds of technology, gender studies and public policy in fully exploring algorithmic accountability as well as in accurately and transparently exploring the potential consequences of the introduction of AI technologies.

Obscured AGN enhancement in galaxy pairs at cosmic noon: evidence from a probabilistic treatment of photometric redshifts

ABSTRACT Observations of the nearby universe reveal an increasing fraction of active galactic nuclei (AGNs) with decreasing projected separation for close galaxy pairs, relative to control galaxies. This implies galaxy interactions play a role in enhancing AGN activity. However, the picture at higher redshift is less established, partly due to limited spectroscopic redshifts. We combine spectroscopic surveys with photometric redshift probability distribution functions for galaxies in the CANDELS and COSMOS surveys, to produce the largest ever sample of galaxy pairs used in an AGN fraction calculation for cosmic noon (0.5 < z < 3). We present a new technique for assessing galaxy pair probability (based on line-of-sight velocities ±1000 km s−1) from photometric redshift posterior convolutions and use these to produce weighted AGN fractions. Over projected separations 5–100 kpc, we find no evidence for enhancement, relative to isolated control galaxies, of X-ray (LX > 1042 erg s−1) or infrared-selected AGN in major (mass ratios up to 4:1) or minor (4:1 to 10:1) galaxy pairs. However, defining the most obscured AGN as those detected in the infrared but not in X-rays, we observe a trend of increasing obscured AGN enhancement at decreasing separations. The peak enhancement, relative to isolated controls, is a factor of 2.08 ± 0.61 for separations <25 kpc. Our simulations with mock data, indicates this could be a lower limit of the true enhancement. If confirmed with improved infrared imaging (e.g. with JWST) and redshifts (e.g. with forthcoming multi-object spectrograph surveys), this would suggest that galaxy interactions play a role in enhancing the most obscured black hole growth at cosmic noon.

The PAU survey: close galaxy pairs identification and analysis

ABSTRACT Galaxy pairs constitute the initial building blocks of galaxy evolution, which is driven through merger events and interactions. Thus, the analysis of these systems can be valuable in understanding galaxy evolution and studying structure formation. In this work, we present a new publicly available catalogue of close galaxy pairs identified using photometric redshifts provided by the Physics of the Accelerating Universe Survey (PAUS). To efficiently detect them, we take advantage of the high-precision photo−z (σ68 < 0.02) and apply an identification algorithm previously tested using simulated data. This algorithm considers the projected distance between the galaxies (rp < 50 kpc), the projected velocity difference (ΔV < 3500 km s−1) and an isolation criterion to obtain the pair sample. We applied this technique to the total sample of galaxies provided by PAUS and to a subset with high-quality redshift estimates. Finally, the most relevant result we achieved was determining the mean mass for several subsets of galaxy pairs selected according to their total luminosity, colour, and redshift, using galaxy–galaxy lensing estimates. For pairs selected from the total sample of PAUS with a mean r-band luminosity 1010.6 h−2 L⊙, we obtain a mean mass of M200 = 1012.2 h−1 M⊙, compatible with the mass–luminosity ratio derived for elliptical galaxies. We also study the mass-to-light ratio M/L as a function of the luminosity L and find a lower M/L (or steeper slope with L) for pairs than the one extrapolated from the measurements in groups and galaxy clusters.

Radiation-induced phenomena in thermally treated Kr matrices

The effect of thermal treatment on relaxation phenomena in Kr matrices irradiated with a low-energy electron beam has been studied. The experiments were carried out using measurements of the relaxation emissions of preirradiated Kr samples, which were unannealed and annealed before exposure to an electron beam. Three types of emissions were monitored in a correlated real-time manner: thermally stimulated luminescence, thermally stimulated exoelectron emission, and total yield of particles via pressure measurements. The energy levels of defects were estimated from the thermally stimulated luminescence data of the annealed sample. Two types of electron-hole traps created by electronic excitation were identified: close pairs and distant ones. Additional confirmation of the “excited state” mechanism of defect formation was obtained. Analysis of the correlation of yields and the effect of thermal treatment gave additional arguments in support of the crowdion model of anomalous low-temperature post-desorption from pre-irradiated Kr matrices.

Early Results from GLASS-JWST. XIX. A High Density of Bright Galaxies at z ≈ 10 in the A2744 Region

We report the detection of a high density of redshift z ≈ 10 galaxies behind the foreground cluster A2744, selected from imaging data obtained recently with NIRCam on board JWST by three programs—GLASS-JWST, UNCOVER, and DDT#2756. To ensure robust estimates of the lensing magnification μ, we use an improved version of our model that exploits the first epoch of NIRCam images and newly obtained MUSE spectra and avoids regions with μ > 5 where the uncertainty may be higher. We detect seven bright z ≈ 10 galaxies with demagnified rest frame −22 ≲ M UV ≲ −19 mag, over an area of ∼37 arcmin2. Taking into account photometric incompleteness and the effects of lensing on luminosity and cosmological volume, we find that the density of z ≈ 10 galaxies in the field is about 10× (3×) larger than the average at M UV ≈ −21 ( −20) mag reported so far. The density is even higher when considering only the GLASS-JWST data, which are the deepest and the least affected by magnification and incompleteness. The GLASS-JWST field contains five out of seven galaxies, distributed along an apparent filamentary structure of 2 Mpc in projected length, and includes a close pair of candidates with M UV < −20 mag having a projected separation of only 16 kpc. These findings suggest the presence of a z ≈ 10 overdensity in the field. In addition to providing excellent targets for efficient spectroscopic follow-up observations, our study confirms the high density of bright galaxies observed in early JWST observations but calls for multiple surveys along independent lines of sight to achieve an unbiased estimate of their average density and a first estimate of their clustering.

Parallelization of the Symplectic Massive Body Algorithm (SyMBA) N-body Code

Direct N-body simulations of a large number of particles, especially in the study of planetesimal dynamics and planet formation, have been computationally challenging even with modern machines. This work presents the combination of fully parallelized N 2/2 interactions and the incorporation of the GENGA code’s close encounter pair grouping strategy to enable MIMD parallelization of the Symplectic Massive Body Algorithm (SyMBA) with OpenMP on multi-core CPUs in shared-memory environment. SyMBAp (SyMBA parallelized) preserves the symplectic nature of SyMBA and shows good scalability, with a speedup of 30.8 times with 56 cores in a simulation with 5000 fully interactive particles.

A Survey for High-redshift Gravitationally Lensed Quasars and Close Quasar Pairs. I. The Discoveries of an Intermediately Lensed Quasar and a Kiloparsec-scale Quasar Pair at z ∼ 5

We present the first results from a new survey for high-redshift (z ≳ 5) gravitationally lensed quasars and close quasar pairs. We carry out candidate selection based on the colors and shapes of objects in public imaging surveys, then conduct follow-up observations to confirm the nature of high-priority candidates. In this paper, we report the discoveries of J0025–0145 (z = 5.07), which we identify as an intermediately lensed quasar, and J2329–0522 (z = 4.85), which is a kiloparsec-scale close quasar pair. The Hubble Space Telescope (HST) image of J0025–0145 shows a foreground lensing galaxy located 0.″6 away from the quasar. However, J0025–0145 does not exhibit multiple lensed images of the quasar, and we identify J0025–0145 as an intermediate lensing system (a lensing system that is not multiply imaged but has a significant magnification). The spectrum of J0025–0145 implies an extreme Eddington ratio if the quasar luminosity is intrinsic, which could be explained by a large lensing magnification. The HST image of J0025–0145 also indicates a tentative detection of the quasar host galaxy in the rest-frame UV, illustrating the power of lensing magnification and distortion in studies of high-redshift quasar host galaxies. Object J2329–0522 consists of two resolved components with significantly different spectral properties and a lack of lensing galaxy detection under subarcsecond seeing. We identify it as a close quasar pair, which is the highest confirmed kiloparsec-scale quasar pair to date. We also report four lensed quasars and quasar pairs at 2 < z < 4 and discuss possible improvements to our survey strategy.

A close quasar pair in a disk-disk galaxy merger at z = 2.17.

Galaxy mergers produce pairs of supermassive black holes (SMBHs), which may be witnessed as dual quasars if both SMBHs are rapidly accreting. The kiloparsec (kpc)-scale separation represents a physical regime sufficiently close for merger-induced effects to be important1 yet wide enough to be directly resolvable with the facilities currently available. Whereas many kpc-scale, dual active galactic nuclei-the low-luminosity counterparts of quasars-have been observed in low-redshift mergers2, no unambiguous dual quasar is known at cosmic noon (z ≈ 2), the peak of global star formation and quasar activity3,4. Here we report multiwavelength observations of Sloan Digital Sky Survey (SDSS) J0749 + 2255 as a kpc-scale, dual-quasar system hosted by a galaxy merger at cosmic noon (z = 2.17). We discover extended host galaxies associated with the much brighter compact quasar nuclei (separated by 0.46″ or 3.8 kpc) and low-surface-brightness tidal features as evidence for galactic interactions. Unlike its low-redshift and low-luminosity counterparts, SDSS J0749 + 2255 is hosted by massive compact disk-dominated galaxies. The apparent lack of stellar bulges and the fact that SDSS J0749 + 2255 already follows the local SMBH mass-host stellar mass relation, suggest that at least some SMBHs may have formed before their host stellar bulges. While still at kpc-scale separations where the host-galaxy gravitational potential dominates, the two SMBHs may evolve into a gravitationally bound binary system in around 0.22 Gyr.

Exploring Thousands of Nearby Hierarchical Systems with Gaia and Speckle Interferometry

There should be about 10,000 stellar hierarchical systems within 100 pc with primary stars more massive than 0.5 M ⊙, and a similar amount of less-massive hierarchies. A list of 8000 candidate multiples is derived from wide binaries found in the Gaia Catalog of Nearby Stars where one or both components have excessive astrometric noise or other indicators of inner subsystems. A subset of 1243 southern candidates were observed with high angular resolution at the 4.1 m Southern Astrophysical Research Telescope, and 503 new pairs with separations from 0.″03 to 1″ were resolved. These data allow estimation of the inner mass ratios and periods, and help to quantify the ability of Gaia to detect close pairs. Another 621 hierarchies with known inner periods come from the Gaia catalog of astrometric and spectroscopic orbits. These two nonoverlapping groups, combined with existing ground-based data, bring the total number of known nearby hierarchies to 2754, reaching a completeness of ∼22% for stars above 0.5 M ⊙. Distributions of their periods and mass ratios are briefly discussed, and the prospects of further observations are outlined.

Structure of interpolymer complex between poly(acrylic acid) and poly(ethylene oxide) in aqueous salt solution: a molecular dynamics simulation study

ABSTRACT Inter-macromolecular interaction between uncharged polymers in aqueous solutions can be influenced by concentration of polymer, solvent quality, molecular weight, solution pH, temperature, salt concentration and type of salt. Atomistic molecular dynamics simulations of aqueous NaCl solution containing poly(acrylic acid) and poly(ethylene oxide) are presented. The size of the polymer chains decreases with an increase in salt concentration resulting from water becoming a poor solvent which enhances compositing of polymers. A close pair is formed between carboxylic hydrogen (−COOH) and ether oxygen (−O−) of the polymer at high salt concentration. The change in structure of the PAA/PEO complex is analysed using simulated SAXS and SANS profiles. The solubility of chains decreases and attains the minimum energy conformation at a particular salt concentration. The solvent accessible surface area (SASA) of the complex at higher salt concentration is less as compared to the lower. Increase in salt concentration enhances the cooperative interaction via hydrogen bonding between PAA and PEO and weakens the polymer-water-hydrogen bonding. The net result is a decrease in solubility of these polymers and thermodynamically stable polymer-polymer complex is formed at higher salt concentrations. Simulation results are in agreement with available experimental data in literature.

Modelling gas around galaxy pairs and groups using the Q0107 quasar triplet

ABSTRACTWe examine to what extent disc and outflow models can reproduce observations of H i gas within a few virial radii of galaxies in pairs and groups. Using highly sensitive HST/COS and FOS spectra of the Q0107 quasar triplet covering Ly α for z≲1, as well as a deep galaxy redshift survey including VIMOS, DEIMOS, GMOS, and MUSE data, we test simple disc and outflow models against the H i absorption along three lines-of-sight (separated by 200–500 kpc) through nine galaxy groups in this field. These can be compared with our previous results in which these models can often be fit to the absorption around isolated galaxies. Our models can reproduce ≈ 75 per cent of the 28 identified absorption components within 500 km s−1 of a group galaxy, so most of the H i around groups is consistent with a superposition of the CGM of the individual galaxies. Gas stripped in interactions between galaxies may be a plausible explanation for some of the remaining absorption, but neither the galaxy images nor the galaxy and absorber kinematics provide clear evidence of such stripped material, and these unexplained absorbers do not preferentially occur around close pairs of galaxies. We find H i column densities typically higher than at similar impact parameters around isolated galaxies (≈ 2.5σ), as well as more frequent detections of O vi than around isolated galaxies (30 per cent of sightlines to 7 per cent).

Effects of dialect familiarity on word identification in a visual-world eye-tracking task

The acoustic closeness of vowels across American English dialects results in cross-dialect lexical competition among minimal pair words. In the current study, we investigated how listener familiarity with specific dialects affects performance in a cross-dialect visual-world eye-tracking task. Listeners heard both acoustically close and control minimal pairs in each of three regional American English dialects (New England, Southern, and Northern) in a four-alternative forced-choice identification task. Listener dialect familiarity was assessed for each dialect based on each individual’s self-reported residential history for themselves, their parents, and their significant others. Preliminary analyses revealed more accurate and faster responses to New England talkers as familiarity with the New England dialect increased, consistent with talker and accent familiarity effects in the literature. However, responses to Southern talkers were slower as familiarity with the Southern dialect increased, contrary to the typical pattern. Responses to Northern talkers were not affected by familiarity with the Northern dialect, consistent with the lack of enregisterment of this variety. Together, these findings suggest that listener dialect familiarity has different effects on the resolution of cross-dialect lexical competition, reflecting both the nature of the variation and the social stereotypes associated with the dialect. Analysis of the eye-tracking data is ongoing.

Sparse and Flexible Convex-Hull Representation for Machine Degradation Modeling

Convex hulls based maximum margin classification has been widely studied for machine fault diagnosis, while its exploration for machine degradation modeling is seldom reported. In this study, a sparse and flexible convex-hull representation for machine degradation modeling is proposed to realize degradation trajectory tracking and fault diagnosis at a same time. First, considering using vibration data as health monitoring signals, globally normal and abnormal spectral lines can be obtained based on the fast Fourier transform and they are, respectively, characterized as individually flexible convex hulls. Subsequently, a sparse and flexible convex-hull representation degradation model is constructed by simultaneously finding the closest pair of samples and its sparse regularization between normal and abnormal convex hulls. Finally, a health indicator can be developed for early fault detection and degradation trajectory tracking during a machine life cycle. Meanwhile, quick fault diagnosis can be realized by finding a difference between the optimal closest samples in a normal convex hull and an abnormal convex hull. Two experimental cases are used to show the effectiveness and superiority of the proposed model to recent existing works.

Efficient distributed algorithms for distance join queries in spark-based spatial analytics systems

ABSTRACT Apache Sedona (formerly GeoSpark) is a new in-memory cluster computing system for processing large-scale spatial data, which extends the core of Apache Spark to support spatial datatypes, partitioning techniques, spatial indexes, and spatial operations (e.g. spatial range, nearest neighbor, and spatial join queries). Distance-based Join Queries (DJQs), like nearest neighbor join (kNNJQ) or closest pairs queries (kCPQ), are not supported by it. Therefore, in this paper, we investigate how to design and implement efficient DJQ distributed algorithms in Apache Sedona, using the most appropriate spatial partitioning and other optimization techniques. The results of an extensive set of experiments with real-world datasets are presented, demonstrating that the proposed kNNJQ and kCPQ distributed algorithms are efficient, scalable, and robust in Apache Sedona. Finally, Sedona is also compared to other similar cluster computing systems, showing the best performance for kCPQ and competitive results for kNNJQ.

Merging black holes in dwarf galaxies: calculating binary black hole coalescence time-scales from simulations forLISAdetection

ABSTRACTSupermassive black holes (SMBHs) merging in dwarf galaxies will be detectable by the Laser Interferometer Space Antenna (LISA) in the mid-2030s. Previous cosmological hydrodynamic simulations have shown the prediction of massive BHs merging in dwarf galaxies, but these simulations are limited by their resolution and cannot follow BH pairs all the way to coalescence. We calculate the delay time between BH pairing and merger based on the properties of the BHs and their host galaxies, and use these properties to calculate gravitational wave strains for eleven different binary BHs that merge inside dwarf galaxies from eight cosmological simulations. This delay time calculation accounts for dynamical friction due to gas and stars, loss-cone scattering, and hardening of the binary due to gravitational radiation. Out of the eleven BH mergers in the simulations, five BH pairs will merge within 0.8–8 Gyr of forming a close pair and could be observed by LISA, and the remaining six are unresolved due to resolution limitations of the simulation. As all five of the resolved close pairs merge within a Hubble time, we make the broad estimate that close SMBH pairs in dwarf galaxies will merge and be detectable by LISA, but this estimate depends on either the presence of gas during orbital decay or a solution to the dynamical buoyancy problem in cored potentials.

SOEDIRMAN-OERIP: DWITUNGGAL PIMPINAN TENTARA NASIONAL INDONESIA TAHUN 1945-1948

This study aims to examine the concept of Dwitunggal which in terminology is defined as a very close and strong pair between two figures, in this case, Soedirman and Oerip Soemohardjo as the first supreme leaders of the Indonesian National Armed Forces in 1945-1948. The research method used in this research is library research. Data and information collection is carried out through books, scientific journals, and other research results that are worthy of being used as sources for research and have been critically and in-depth analyzed so that they can be used to support ideas in research. The findings obtained in this study are that differences in background are not always a barrier in building good relationships to achieve a goal, as seen in the story of Dwitunggal Soedirman-Oerip. It is known that Soedirman and Oerip had different backgrounds, namely Soedirman came from PETA while Oerip came from the KNIL, which at that time was considered a Dutch colonial army. Even so, the two can still work together and complement each other. Soedirman handled military politics while Oerip handled military techniques. This shows that Soedirman and Oerip did not see differences in one another's backgrounds as a barrier, but instead as a strength in building good relations to achieve common goals.

Permutations that separate close elements

Let n be a fixed integer with n≥2. For i,j∈Zn, define ||i,j||n to be the distance between i and j when the elements of Zn are written in a cycle. So ||i,j||n=min⁡{(i−j)modn,(j−i)modn}. For positive integers s and k, the permutation π:Zn→Zn is (s,k)-clash-free if ||π(i),π(j)||n≥k whenever ||i,j||n<s with i≠j. So an (s,k)-clash-free permutation π can be thought of as moving every close pair of elements of Zn to a pair at large distance. More geometrically, the existence of an (s,k)-clash-free permutation is equivalent to the existence of a set of n non-overlapping s×k rectangles on an n×n torus, whose centres have distinct integer x-coordinates and distinct integer y-coordinates.For positive integers n and k with k<n, let σ(n,k) be the largest value of s such that an (s,k)-clash-free permutation on Zn exists. In a recent paper, Mammoliti and Simpson conjectured that⌊(n−1)/k⌋−1≤σ(n,k)≤⌊(n−1)/k⌋ for all integers n and k with k<n. The paper establishes this conjecture, by explicitly constructing an (s,k)-clash-free permutation on Zn with s=⌊(n−1)/k⌋−1. Indeed, this construction is used to establish a more general conjecture of Mammoliti and Simpson, where for some fixed integer r we require every point on the torus to be contained in the interior of at most r rectangles.

SDSS-IV MaNGA: How Galaxy Interactions Influence Active Galactic Nuclei

We present a comparative study of active galactic nuclei (AGN) between galaxy pairs and isolated galaxies with the final data release of the MaNGA integral field spectroscopic survey. We build a sample of 391 kinematic galaxy pairs within the footprint of the survey and select AGN using the survey's spectra. We use the comoving volume densities of the AGN samples to quantify the effects that tidal interactions have on the triggering of nuclear accretion. Our hypothesis is that the pair sample contains AGN that are triggered by not only stochastic accretion but also tidally induced accretion and correlated accretion. With the level of stochastically triggered AGN fixed by the control sample, we model the strength of tidally induced accretion and correlated accretion as a function of projected separation (r p ) and compare the model expectations with the observed volume densities of dual AGN and offset AGN (single AGN in a pair). At r p ∼ 10 kpc, we find that tidal interactions induce ∼30% more AGN than stochastic fueling and cause ∼12% of the offset AGN to become dual AGN because of correlations. The strength of both these effects decreases with increasing r p . We also find that the [O iii] luminosities of the AGN in galaxy pairs are consistent with those found in isolated galaxies, likely because stochastically fed AGN dominate even among close pairs. Our results illustrate that while we can detect tidally induced effects statistically, it is challenging to separate tidally induced AGN and stochastically triggered AGN in interacting galaxies.

Many Hands Make Light Work: Transferring Knowledge From Auxiliary Tasks for Video-Text Retrieval

The problem of video-text retrieval, which searches videos via natural language descriptions or vice versa, has attracted growing attention due to the explosive scale of videos produced every day. The dominant approaches for this problem follow the pipeline that firstly learn compact feature representations of videos and texts, and then jointly embed them into a common feature space where matched video-text pairs are close and unmatched pairs are far away. However, most of them neither consider the structural similarities among crossmodal samples in a global view, nor leverage useful information from other relevant retrieval processes. We argue that both information have great potential for video-text retrieval. In this paper, we propose to extract useful knowledge from the retrieval process by exploiting structural similarities via Graph Neural Networks (GNNs) and then progressively transfer useful knowledge from relevant retrieval processes in a general-tospecific manner to assist the current retrieval process. Specifically, for the retrieval of the current query, we first construct a sequence of query-graphs whose central queries are chosen from distant to close to the current query. Then we conduct knowledgeguided message passing in each query-graph to exploit regional structural similarities and gather knowledge of different levels from the updated query-graphs with a knowledge-based attention mechanism. Finally, we transfer the extracted useful knowledge from general to specific to assist the current retrieval process. Extensive experimental results show that our model outperforms the state-of-the-arts on four benchmarks.