Merging Systems Research Articles

Integrative exposomic, transcriptomic, epigenomic analyses of human placental samples links understudied chemicals to preeclampsia.

Environmental health research has recently undergone a dramatic shift, with ongoing technological advancements allowing for broader coverage of exposure and molecular biology signatures. Approaches to integrate such measures are still needed to increase understanding between systems-level exposure and biology. We address this gap by evaluating placental tissues to identify novel chemical-biological interactions associated with preeclampsia. This study tests the hypothesis that understudied chemicals are present in the human placenta and associated with preeclampsia-relevant disruptions, including overall case status (preeclamptic vs. normotensive patients) and underlying transcriptomic/epigenomic signatures. A non-targeted analysis based on high-resolution mass spectrometry was used to analyze placental tissues from a cohort of 35 patients with preeclampsia (n = 18) and normotensive (n = 17) pregnancies. Molecular feature data were prioritized for confirmation based on association with preeclampsia case status and confidence of chemical identification. All molecular features were evaluated for relationships to mRNA, microRNA, and CpG methylation (i.e., multi-omic) signature alterations involved in preeclampsia. A total of 183 molecular features were identified with significantly differentiated abundance in placental extracts of preeclamptic patients; these features clustered into distinct chemical groupings using unsupervised methods. Of these features, 53 were identified (mapping to 40 distinct chemicals) using chemical standards, fragmentation spectra, and chemical metadata. In general, human metabolites had the largest feature intensities and strongest associations with preeclampsia-relevant multi-omic changes. Exogenous drugs were second most abundant and had fewer associations with multi-omic changes. Other exogenous chemicals (non-drugs) were least abundant and had the fewest associations with multi-omic changes. These global data trends suggest that human metabolites are heavily intertwined with biological processes involved in preeclampsia etiology, while exogenous chemicals may still impact select transcriptomic/epigenomic processes. This study serves as a demonstration of merging systems exposures with systems biology to better understand chemical-disease relationships.

Origin and Evolution of Dust-obscured Galaxies in Galaxy Mergers

Dust-obscured galaxies (DOGs), which are observationally characterized as faint in the optical and bright in the infrared, are the final stage of galaxy mergers and are essential objects in the evolution of galaxies and active galactic nuclei (AGNs). However, the relationship between the torus-scale gas dynamics around AGNs and the DOGs’ lifetime remains unclear. We obtained the evolution of the spectral energy distributions (SEDs) of a galaxy merger system with AGN feedback from postprocessed pseudo-observations based on an N-body/smoothed particle hydrodynamics (SPH) simulation. We focused on a late-stage merger of two identical galaxies with a supermassive black hole (SMBH) of 108 M ⊙. We found that the infrared luminosity of the system reaches ultra- and hyperluminous infrared galaxy classes (1012 and 1013 L ⊙, respectively). The DOG phase corresponds to a state in which the AGNs are buried in dense gas and dust, with the infrared luminosity exceeding 3.3 × 1012 L ⊙. We also identified subcategories of DOGs, namely bump and power-law DOGs, from the SEDs and their evolution. The bump DOGs tend to evolve to power-law DOGs over several Myrs. We found that contribution from the hot dust around the nucleus in the infrared radiation is essential for identifying the system as a power-law DOG; the gas and dust are distributed nonspherically around the nucleus, therefore, the observed properties of DOGs depend on the viewing angle. In our model, the lifetime of merger-driven DOGs is less than 4 Myr, suggesting that the observed DOG phase is a brief aspect of galaxy mergers.

Star Formation Suppression by Tidal Removal of Cold Molecular Gas from an Intermediate-redshift Massive Post-starburst Galaxy

Observations and simulations have demonstrated that star formation in galaxies must be actively suppressed to prevent the formation of overly massive galaxies. Galactic outflows driven by stellar feedback or supermassive black hole accretion are often invoked to regulate the amount of cold molecular gas available for future star formation but may not be the only relevant quenching processes in all galaxies. We present the discovery of vast molecular tidal features extending up to 64 kpc outside of a massive z = 0.646 post-starburst galaxy that recently concluded its primary star-forming episode. The tidal tails contain (1.2 ± 0.1) × 1010 M ⊙ of molecular gas, 47% ± 5% of the total cold gas reservoir of the system. Both the scale and magnitude of the molecular tidal features are unprecedented compared to all known nearby or high-redshift merging systems. We infer that the cold gas was stripped from the host galaxies during the merger, which is most likely responsible for triggering the initial burst phase and the subsequent suppression of star formation. While only a single example, this result shows that galaxy mergers can regulate the cold gas contents in distant galaxies by directly removing a large fraction of the molecular gas fuel, and plausibly suppress star formation directly, a qualitatively different physical mechanism than feedback-driven outflows.

Key drivers, challenges and strategies towards successful low-carbon campus: the case of UiTM Shah Alam campus

PurposeThere is a growing awareness of the dangers of climate change and global warming due to increasing energy consumption and associated greenhouse gas emissions. Campus universities are critical for implementing low-carbon development efficiently, given the large population and socio-economic activities concentrated on campus. This paper aims to explore the existing campus management initiatives and recommends holistic driving elements towards successful low-carbon campus development.Design/methodology/approachThis study’s triangulation of information was supplemented by contributions from 116 respondents on the UiTM Shah Alam campus and eight professional interviews with stakeholders involved in low-carbon campus projects.FindingsThe study reported that low-carbon strategies had been implemented on the UiTM Shah Alam campus, with most existing programmes and activities focusing on low-hanging fruit initiatives. Moreover, the findings indicate that financial, cultural, behavioural, organisational and physical constraints are critical challenges to effectively implementing low-carbon approaches. The proposed techniques suggest that generating green funding, defining clear targets, developing standard procedures for carbon assessment and monitoring, also boosting education and outreach programmes lead to the improvement of low-carbon campus efforts.Practical implicationsThe outcomes of this paper offer perspective to campus administration and community into an evaluation of current approaches and strategies for merging low-carbon systems. The effectiveness of low-carbon implementation was ensured by addressing issues concerning low-carbon uptake and fostering low-carbon improvement.Originality/valueBesides providing a better understanding of techniques to implementing low-carbon development in Malaysia, the critical hurdles and driving factors, the output from this study adds to the existing knowledge available concerning the campus community’s existing comprehension.

Constraining neutron star properties with a new equation of state insensitive approach

Instead of parameterizing the pressure-density relation of a neutron star (NS), one can parameterize its macroscopic properties such as mass ($M$), radius ($R$), and dimensionless tidal deformability ($\Lambda$) to infer the equation of state (EoS) combining electromagnetic and gravitational wave (GW) observations. We present a new method to parameterize $R(M)$ and $\Lambda(M)$ relations, which approximate the candidate EoSs with accuracy better than 5\% for all masses and span a broad region of $M-R-\Lambda$ plane. Using this method we combine the $M-\Lambda$ measurement from GW170817 and GW190425, and simultaneous $M-R$ measurement of PSR J0030+0451 and PSR J0740+6620 to place joint constraints on NS properties. At 90 \% confidence, we infer $R_{1.4}=12.05_{-0.87}^{+0.98}$ km and $\Lambda_{1.4}=372_{-150}^{+220}$ for a $1.4 M_{\odot}$ NS, and $R_{2.08}=12.65_{-1.46}^{+1.36}$ km for a $2.08 M_{\odot}$ NS. Furthermore, we use the inferred values of the maximum mass of a nonrotating NS $M_{\rm max}=2.52_{-0.29}^{+0.33} M_{\odot}$ to investigate the nature of the secondary objects in three potential neutron star-black hole merger (NSBH) system.

Modeling the effects of ecosystem changes on seagrass wrack valorization: Merging system dynamics with life cycle assessment

Seagrass meadows, while recognized as essential ecosystem service providers, are degrading worldwide. This has a profound impact on the environment but also on socioeconomic systems which hope to utilize beach-cast seagrass (wrack) as a bioresource. This study integrates system dynamics (SD) thinking with life cycle assessment (LCA) and life cycle costing (LCC) to understand how a degraded ecosystem feedbacks into the circular bioeconomy. An SD model was created to assess the impacts of seagrass meadow changes on wrack production and on ecosystem services accounting, considering an Italian case study of wrack deposited on a beach. Environmental and economic impacts of wrack valorization through anaerobic digestion (AD) were then determined through LCA and LCC. Finally, an extended LCC combined the results of the SD model, LCA, and LCC to demonstrate the cost of seagrass meadow degradation and the value of restoration. The results confirmed complexities in stakeholder perspective within the waste-to-resource framework. For the AD operator, meadow restoration would increase the profits from wrack valorization (23.10 €/ton), while for the municipality, meadow degradation would reduce the high costs associated with management (104.29–140.00 €/ton). When also considering the impacts on the environment and local community, valuation of ecosystem services and cost of restoration were influential. Meadow restoration with wrack valorization was the most favorable option if the natural capital of the seagrass meadows was valued appropriately (>0.065 €/m2) and direct costs of restoration could be kept relatively low (<1179 €/ha). Overall, the model resulted in a total net present cost of −3.161,462.40 € for the baseline scenario, −1,488,277.28 € for the scenario of wrack valorization, and −1,231,325.12 € for the scenario of wrack valorization and meadow restoration.

Parameterised population models of transient non-Gaussian noise in the LIGO gravitational-wave detectors

The two interferometric LIGO gravitational-wave observatories provide the most sensitive data to date to study the gravitational-wave universe. As part of a global network, they have completed their third observing run in which they observed many tens of signals from merging compact binary systems. It has long been known that a limiting factor in identifying transient gravitational-wave signals is the presence of transient non-Gaussian noise, which reduce the ability of astrophysical searches to detect signals confidently. Significant efforts are taken to identify and mitigate this noise at the source, but its presence persists, leading to the need for software solutions. Taking a set of transient noise artefacts categorised by the GravitySpy software during the O3a observing era, we produce parameterised population models of the noise projected into the space of astrophysical model parameters of merging binary systems. We compare the inferred population properties of transient noise artefacts with observed astrophysical systems from the GWTC2.1 catalogue. We find that while the population of astrophysical systems tend to have near equal masses and moderate spins, transient noise artefacts are typically characterised by extreme mass ratios and large spins. This work provides a new method to calculate the consistency of an observed candidate with a given class of noise artefacts. This approach could be used in assessing the consistency of candidates found by astrophysical searches (i.e. determining if they are consistent with a known glitch class). Furthermore, the approach could be incorporated into astrophysical searches directly, potentially improving the reach of the detectors, though only a detailed study would verify this.

Air traffic management in parallel-point merge systems under wind uncertainties

The point merge system (PMS) was developed by EUROCONTROL in 2006 to enable controllers to implement systematic sequences and replace the traditional vector technique in Terminal Maneuver Area (TMA) even during peak hours. A conventional PMS includes two arc-shaped route segments referred to as sequencing legs and a single merge point to merge arrivals. When necessary, arrivals can be delayed along these legs using path stretching before they are directed to the merge point. After merging, aircraft join the final approach. The parallel-point merge system (P-PMS), however, has a more complex route structure which consists of two oppositely located PMS and a set of common points located between the merge points and final paths of runways. This system increases the capacity of the airspace and provides the advantages of the single PMS. However, especially in simulation studies where P-PMS has been tested, the emphasis on wind sensitivity came to the fore as one of the main issues affecting the use of the system. The use of P-PMS was stated as feasible but more difficult due to the loss of symmetry, especially when the wind is perpendicular to the sequencing legs. Controllers may need help in providing safe and efficient sequences in this type of structure. In this study, a multi-objective two-stage stochastic programming model is developed for P-PMS to obtain robust aircraft sequences, schedules, and runway assignments considering the uncertainties of both wind direction and speed. The model was implemented on the existing layout of Istanbul Airport having a P-PMS serving five parallel runways using the real traffic and wind data. A scenario-based approach was adopted to represent the uncertainties of the model. Also, to meet the demands of the various stakeholders in the air traffic system, the minimization of total fuel consumption, total flight time, and total delays were considered as single and multi-objectives. As a result, it was found that the stochastic approach provides better solutions in terms of objective values and emission outputs compared to deterministic and FCFS approaches under wind uncertainties. The differences between these solutions are quantified through numerical experiments.

Emission and Flight Time Optimization Model for Aircraft Landing Problem

Aircraft landing is a critical operation for both terminal airspaces and airports. This study presents a multi-objective optimization model for this problem and aims to minimize the total flight time and emission value. A point merge system and vector maneuver techniques are implemented in aircraft to regulate air traffic. The model uses the augmented è-constraint method to reveal objective function relationships. To test the performance of the mathematical model, several realistic scenarios are generated and solved by GAMS/CPLEX solver. The algorithm can obtain Pareto-optimal solutions for each air traffic situation. In addition, noticeable reductions were observed in most of the Pareto-optimal solutions in emission values. The results showed that total emissions value and flight time were reduced up to 4.69% and 0.92%, respectively, compared with the first-come-first-served approach.

The velocity structure of the intracluster medium during a major merger: Simulated microcalorimeter observations

Major mergers between galaxy clusters can produce large turbulent and bulk flow velocities in the intracluster medium (ICM) and thus imprint useful diagnostic features in X-ray spectral emission lines from heavy ions. As successfully achieved by Hitomi in observations of the Perseus cluster, measurements of gas velocities in clusters from high-resolution X-ray spectra will be achievable with upcoming X-ray calorimeters such as those on board XRISM, Athena, or a Lynx like mission. An interesting application to clusters involves detecting multiple velocity components or velocity gradients from diagnostic observations of specific interesting locations across the cluster. To explore this possibility in the case of a major head-on cluster merger, we performed velocity analyzes of a cluster-cluster merger from a hydrodynamical simulation by means of X-ray synthetic spectra with a spectral resolution on the order of a few eV. We observed the system along two extreme line-of-sight directions: (1) perpendicular to the plane of the merger and (2) along the merger axis. In these geometrical configurations, we found that clear non-Gaussian shapes of the iron He-like Kα line at 6.7 keV are expected. While the velocity dispersion predicted from the simulations can be retrieved for the brightest 100 ks pointings with XRISM Resolve, some discrepancy with respect to the expected value is noted and can be attributed to the complex non-Gaussian line shapes. Measurements in low surface brightness regions, especially when multiple velocity components are present along the line of sight, require high signal-to-noise ratio and the larger collecting area of the Athena X-IFU calorimeter is therefore required. With the latter, we also investigated the ICM temperature and velocity gradient across the merger bow shock edge, from 20″-wide annuli extracted from a single 1 Ms X-IFU observation. For both temperature and velocity dispersion, we found best-fit values that are consistent with predictions from the simulations within 1-σ. The uncertainties on the inferred velocity dispersion are, however, too large to place any stringent constraints on the shallow gradient downstream of the shock. Additionally, we present simulated images of the thermal and kinetic Sunyaev–Zeldovich effects from this merging system, using the above viewing configurations and compare the results at angular resolutions appropriate for future observatories such as CMB-S4 and the Atacama Large Aperture Submillimeter Telescope (AtLAST).

Stability of Discrete-Time Systems Under Restricted Switching via Logic Dynamical Generator and STP-Based Mergence of Hybrid States

In this article, we propose a novel technique for the stability analysis of discrete-time switched systems under constrained switching based on the semitensor product (STP) of matrices and vector-representation of logic. We assume that the admissible switching signals are generated by a logic dynamical system, referred to as the logic dynamical generator (LDG) of the admissible switching. We demonstrate that switching with minimum dwell-time and restricted successors represent two special cases of this type, by constructing their respective LDGs. First, we transfer the LDG into algebraic form, based on the vector-representation of logic. Next, we merge the logic state of the LDG and the continuous state of the original switched system using the STP and derive the dynamics of the merged state; a switched system without constraints on switching. The stability of the switched system under constrained switching is equivalent to the stability of the merged system under arbitrary switching. Based on this, sufficient conditions for the asymptotical stability of nonlinear switched systems with analytic subsystems under constrained switching are obtained. Specifically, in the case of all subsystems being linear, necessary and sufficient conditions for asymptotical stability under constrained switching are proposed.

A Path Stretching Model for Effective Terminal Airspace Management

This study presents a mathematical model to optimize the total fuel consumption per aircraft for the aircraft landing problem (ALP) using the path stretching (PS) method. The PS model applies vector maneuver (VM), speed reduction (SR), and flight path angle (FPA) change methods for aircraft operation. In addition, two different mixed-integer linear programming models utilizing the point merge system (PMS) are presented to compare the PS model as PMS is a widely used method in ALP. The first PMS model uses the VM to handle arrival traffic and solve aircraft conflicts. The second one implements the VM and the SR techniques. Furthermore, an exact solution algorithm is selected to obtain the optimal solution. The PS model aims to increase the number of continuous descent operations by eliminating the level flights. Two different linear regression equations are generated to calculate the fuel consumption and flight time values in descent operations considering realistic aircraft parameters, FPA, and average airspeed. The results demonstrate that the PS model can reduce the total fuel consumption per aircraft by 8.94% and 3.45% compared to the PMS models.

Circumnuclear Medium around the Central AGN in a Cool-core Cluster, Abell 1644-South

We present the circumnuclear multiphase gas properties of the brightest cluster galaxy (BCG) in the center of Abell 1644-South (A1644-S). A1644-S is the main cluster in a merging system, which is well known for X-ray hot gas sloshing in its core. The sharply peaked X-ray profile of A1644-S implies the presence of a strongly cooling gas core. In this study, we analyze ALMA 12CO (1–0) data, JVLA H i data, and KaVA 22 GHz data for the central region of A1644-S to probe the potential origin of the cool gas and its role in (re)powering the central active galactic nucleus (AGN). We find CO clumps distributed in an arc shape along the X-ray gas sloshing, which is suggestive of a connection between the cold gas and the hot intracluster medium (ICM). H i and CN are detected in absorption against the AGN continuum emission. The absorption dip is observed at the systemic velocity of the BCG with an extended, redshifted tail. Based on the spatial and spectral configurations of the H i, CN, and CO gases, it is inferred that cool gas spirals into the core of the BCG, which is then fed to the central AGN. Indeed, our KaVA observation reveals a parsec-scale bipolar jet, implying that this AGN could have been (re)powered quite recently. Combining this, we suggest that some cold gas in A1644-S could have been formed from the cooling of the ICM, triggering the activity of the central AGN in the early development of a cool-core cluster.

Updating conditional probabilities of Bayesian belief networks by merging expert knowledge and system monitoring data

Bayesian Belief Network (BBN) methods can be adopted for reliability analysis and real-time monitoring of critical infrastructure. Conditional Probability Tables (CPTs) are used to describe the dependencies between nodes in the BBN. The CPTs are usually defined by using either expert knowledge elicitation process or data-driven learning methods, and in particular, these methods define the CPTs statically, i.e. the CPTs are defined based only on the information available at the beginning of the analysis process. Therefore, the CPTs represent the correlation between the different components at one point in time, and potential correlations, evolving over time, are neglected.In this paper, a novel method to update the CPTs over time by merging expert judgement and the data about the system behaviour is proposed, which allows a process of continuous updating of CPTs. First of all, the method defines the CPTs by using the expert knowledge elicitation process. Then the CPTs are continuously updated whenever new data-driven evidence about the system becomes available. The proposed method is verified by assessing the health state of an in-field bridge, which experiences different magnitudes of damage. The BBN analysis of the health state of the bridge shows that the proposed method improves the accuracy of the BBN analysis, improving the diagnostics capabilities of the BBN up to 20%, by relying on a more robust and continuous updating of the CPTs.

Programmable graphene-based microfluidic sensor for DNA detection

This study presents the development of a lab-on-a-chip (LoC) by integrating a graphene field-effect transistor (FET) chip with a programmable microfluidic device for DNA detection. The real-time biochemical events on the graphene FET chip were monitored through Dirac voltage shift data from the portable graphene curve reader with changes dependent on the fluidic flow into the sensing interface by a fully automated programmable microfluidic system. High sensitivity with high reliability can be obtained with a nine-graphene sensor layout on a single chip. The portable graphene curve reader also provides a tunable electrical parameter setup and straightforward data acquisition. Fluidic control was performed through a multi-position valve, allowing sequential commands for liquid injection into the polydimethylsiloxane (PDMS) flow cell mounted on the sensing chip. The flow cell design with impinging jet geometry and the microfluidic system packaging offer high precision and portability as a less laborious and low-cost sensing setup. The merged system allows for various functionalities, including probe DNA (pDNA) immobilization, a blocking step, and DNA hybridization with stable signal output autonomously, even in a long-run experimental setup. As a DNA sensor, the proposed prototype has demonstrated a high sensitivity of ~44 mV/decade of target DNA concentration, with an outstanding limit of detection (LoD) of ~0.642 aM, making it one of the most sensitive sensors reported up to date. The programmable device has demonstrated essential versatilities for biomolecular detection in a fully portable and automated platform.

Studying the merging cluster Abell 3266 with eROSITA

Abell 3266 is one of the X-ray brightest galaxy clusters in the sky and is a well-known merging system. Using the ability of the eROSITA telescope onboard SRG (Spectrum Röntgen Gamma) to observe a wide field with a single pointing, we analysed a new observation of the cluster out to a radius of R200. The X-ray images highlight sub-structures present in the cluster, including the north-east-south-west merger seen in previous ASCA, Chandra, and XMM-Newton data, a merging group towards the north-west, and filamentary structures between the core and one or more groups towards the west. We compute spatially resolved spectroscopic maps of the thermodynamic properties of the cluster, including the metallicity. The merging subclusters are seen as low entropy material within the cluster. The filamentary structures could be the rims of a powerful outburst of an active galactic nucleus, or most likely material stripped from the western group(s) as they passed through the cluster core. Seen in two directions is a pressure jump at a radius of 1.1 Mpc, which is consistent with a shock with a Mach number of ~1.5–1.7. The eROSITA data confirm that the cluster is not a simple merging system, but it is made up of several subclusters which are merging or will shortly merge. We computed a hydrostatic mass from the eROSITA data, finding good agreement with a previous XMM-Newton result. With this pointing we detect several extended sources, where we find secure associations between z = 0.36–1.0 for seven of them, that is background galaxy groups and clusters, highlighting the power of eROSITA to find such systems.

Radio properties of the OH megamaser galaxy IIZw 096

Based on the two-epoch European Very Long Baseline Interferometry (VLBI) Network (EVN) archive data from OH line observations of IIZw 096, we confirm that the high-resolution OH emission in this source mainly comes from two spots (OH1 and OH2) of component (comp) D1 of this merging system. We found no significant variations in the OH 1667 MHz line emission, including flux densities and peak positions. The OH 1665 MHz line emission is detected at about the 6σ level in the OH1 region by combining two epochs of EVN observations. By using archival data from the Very Long Baseline Array (VLBA), Very Large Array (VLA), and Atacama Large Millimeter Array (ALMA) observations, we investigated the properties of the environment of this component through H I, CO(3-2), and HCO+(4-3) lines and the multi-band radio continuum emission. We found that the comp D1 shows the brightest CO, HCO+ line emission, as well as multi-band radio continuum emission. The environment around D1 shows no clear velocity structure associated with circular motions, making it different from most other OH megamasers (OHMs) in the literature, which might have been caused by an effect during the merger stage. Meanwhile, we found that the CO emission shows three velocity structures around D1, including the central broad full width at half maximum (FWHM) region, the double-peak region where the CO line profile shows two separated peaks, and the region of the high-velocity clouds where the CO line peaks at a high velocity (∼11 000 km s−1). Similarly, H Iobservations in absorption also show high-velocity clouds around the D1 region, which might be due to inflows caused by the merging of two or more galaxy components. Based on the high-resolution K-band VLA and L-band VLBA observations of the radio continuum emission, we derived the brightness temperature in the range 105 K–106 K, which is consistent with other starburst dominant OHM sources in the literature. The multi-band VLA observations show that the radio continuum emission of comp D might also have contributions from free-free emission in addition to synchrotron emission. As a consequence, these results support a starburst origin for the OHMs, without the presence of an active galactic nucleus (AGN).

Cooperative Ramp Merging Design and Field Implementation: A Digital Twin Approach Based on Vehicle-to-Cloud Communication

Ramp merging is considered as one of the most difficult driving scenarios due to the chaotic nature in both longitudinal and lateral driver behaviors (namely lack of effective coordination) in the merging area. In this study, we have designed a cooperative ramp merging system for connected vehicles, allowing merging vehicles to cooperate with others prior to arriving at the merging zone. Different from most of the existing studies that utilize dedicated short-range communication, we adopt a Digital Twin approach based on vehicle-to-cloud communication. On-board devices upload the data to the cloud server through the 4G/LTE cellular network. The server creates Digital Twins of vehicles and drivers whose parameters are synchronized in real time with their counterparts in the physical world, processes the data with the proposed models in the digital world, and sends advisory information back to the vehicles and drivers in the physical world. A real-world field implementation has been conducted in Riverside, California, with three passenger vehicles. The results show the proposed system addresses the issues of safety and environmental sustainability with an acceptable communication delay, compared to the baseline scenario where no advisory information is provided during the merging process.

Formation and evolution of young massive clusters in galaxy mergers: the SMUGGLE view

ABSTRACT Galaxy mergers are known to host abundant young massive cluster (YMC) populations, whose formation mechanism is still not well-understood. Here, we present a high-resolution galaxy merger simulation with explicit star formation and stellar feedback prescriptions to investigate how mergers affect the properties of the interstellar medium and YMCs. Compared with a controlled simulation of an isolated galaxy, the mass fraction of dense and high-pressure gas is much higher in mergers. Consequently, the mass function of both molecular clouds and YMCs becomes shallower and extends to higher masses. Moreover, cluster formation efficiency is significantly enhanced and correlates positively with the star formation rate surface density and gas pressure. We track the orbits of YMCs and investigate the time evolution of tidal fields during the course of the merger. At an early stage of the merger, the tidal field strength correlates positively with YMC mass, λtid ∝ M0.71, which systematically affects the shape of the mass function and age distribution of the YMCs. At later times, most YMCs closely follow the orbits of their host galaxies, gradually sinking into the centre of the merger remnant due to dynamical friction, and are quickly dissolved via efficient tidal disruption. Interestingly, YMCs formed during the first passage, mostly in tidal tails and bridges, are distributed over a wide range of galactocentric radii, greatly increasing their survivability because of the much weaker tidal field in the outskirts of the merger system. These YMCs are promising candidates for globular clusters that survive to the present day.

VLA detects CO(1–0) emission in the z = 3.65 quasar SDSS J160705+533558

We present CO(1–0) observations of the high-redshift quasar SDSS J160705+533558 (z = 3.653) using the Karl G. Jansky Very Large Array (VLA). We detect CO emission associated with the quasar and at ∼16.8 kpc projected distance from it, separated by ∼800 km s−1 in velocity. The total molecular gas mass of this system is ∼5 × 1010 M⊙. By comparing our CO detections with previous submillimetre (submm) observations of the source, an offset between the different emission components is revealed: the peak of the submm emission is offset from the quasar and from the CO companion detected in our VLA data. To explain our findings, we propose a scenario similar to that for the Antennae galaxies: SDSS J160705+533558 might be a merger system in which the quasar and the CO companion are the merging galaxies, whose interaction resulted in the formation of a dusty, star-forming overlap region between the galaxies that is dominant at the submm wavelengths.