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The BPT Diagram in Cosmological Galaxy Formation Simulations: Understanding the Physics Driving Offsets at High-Redshift

The Baldwin, Philips, & Terlevich diagram of [O III]/Hβ vs. [N II]/Hα (hereafter N2-BPT) has long been used as a tool for classifying galaxies based on the dominant source of ionizing radiation. Recent observations have demonstrated that galaxies at z∼2 reside offset from local galaxies in the N2-BPT space. In this paper, we conduct a series of controlled numerical …

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Deep Extragalactic VIsible Legacy Survey (DEVILS): Evolution of the σSFR-M⋆ relation and implications for self-regulated star formation

We present the evolution of the star-formation dispersion – stellar mass relation (σSFR-M⋆) in the DEVILS D10 region using new measurements derived using the ProSpect spectral energy distribution fitting code. We find that σSFR-M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1<z<0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical …

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Introducing ASTROMOVES

The ASTROMOVES project studies the career moves and the career decision-making of astrophysicists. The astrophysicists participating have to have made at least two career moves after receiving their doctorates, which is usually between 4 and 8 years post PhD. ASTROMOVES is funded via the European Union and thus each participant must have worked or lived …

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MeerKAT discovers mystery clouds

An international team led by astronomers Gyula Józsa, Michelle Cluver, and Thomas Jarrett has utilized the South African MeerKAT telescope to discover a mysterious chain of hydrogen gas clouds the size of a massive galaxy. Indeed, the accumulation of so much elemental hydrogen without associated stellar components is the largest yet discovered. Appearing at the …

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How baryons affect halos and large-scale structure: a unified picture from the Simba simulation

Using the state-of-the-art suite of hydrodynamic simulations Simba, as well as its dark-matter-only counterpart, we study the impact of the presence of baryons and of different stellar/AGN feedback mechanisms on large-scale structure, halo density profiles, and on the abundance of different baryonic phases within halos and in the intergalactic medium (IGM). The unified picture that …

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Cosmological constraints on Newton’s gravitational constant

We study the variation of the gravitational Newton’s constant on cosmological scales in scalar-tensor theories of gravity. We focus on the simplest models of scalar-tensor theories with a coupling to the Ricci scalar of the form F(σ)=N2pl+ξσ2, such as extended Jordan-Brans-Dicke (Npl=0), or a non-minimally coupled scalar field with Npl=Mpl, which permits the gravitational constant to vary …

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Measurements of the diffuse Galactic synchrotron spectral index and curvature from MeerKLASS pilot data

21cm intensity mapping experiments are bringing an influx of high spectral resolution observational data in the ∼100 MHz −1 GHz regime. We use pilot 971−1075 MHz data from MeerKAT in single-dish mode, recently used to test the calibration and data reduction scheme of the upcoming MeerKLASS survey, to probe the spectral index of diffuse synchrotron emission below 1 GHz within 145∘<α<180∘, −1∘<δ<8∘. Through …

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Inferring halo masses with Graph Neural Networks

Understanding the halo-galaxy connection is fundamental in order to improve our knowledge on the nature and properties of dark matter. In this work we build a model that infers the mass of a halo given the positions, velocities, stellar masses, and radii of the galaxies it hosts. In order to capture information from correlations among …

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High Molecular-Gas to Dust Mass Ratios Predicted in Most Quiescent Galaxies

Observations of cold molecular gas reservoirs are critical for understanding the shutdown of star formation in massive galaxies. While dust continuum is an efficient and affordable tracer, this method relies upon the assumption of a “normal” molecular-gas to dust mass ratio, δGDR, typically of order one hundred. Recent null detections of quiescent galaxies in deep dust …

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Large MeerKAT data release reveals beautiful new cosmic puzzles

An international team led by a young South African researcher has just announced a comprehensive overview paper for the MeerKAT Galaxy Cluster Legacy Survey (MGCLS). The paper to be published in the Astronomy & Astrophysicsjournal presents some exciting, novel results, and is accompanied by the public release of a huge trove of curated data now available …

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