The SAMI Galaxy Survey: Gas velocity dispersions in low-$z$ star-forming galaxies and the drivers of turbulence
Mathew R. Varidel, Scott M. Croom, Geraint F. Lewis, Deanne B. Fisher, Karl Glazebrook, Barbara Catinella, Luca Cortese, Mark R. Krumholz, Joss Bland-Hawthorn, … 展开作者
Mathew R. Varidel, Scott M. Croom, Geraint F. Lewis, Deanne B. Fisher, Karl Glazebrook, Barbara Catinella, Luca Cortese, Mark R. Krumholz, Joss Bland-Hawthorn, Julia J. Bryant, Brent Groves, Sarah Brough, Christoph Federrath, Jon S. Lawrence, Nuria P. Lorente, Matt S. Owers, Samuel N. Richards, Ángel R. López-Sánchez, Sarah M. Sweet, Jesse van de Sande, Sam P. Vaughan
We infer the intrinsic ionised gas kinematics for 383 star-forming galaxies across a range of integrated star-formation rates (SFR $\in [10^{-3}, 10^2]$ M$_\odot$ yr$^{-1}$) at $z \lesssim 0.1$ using a consistent 3D forward-modelling technique. The total sample is a combination of galaxies from the SAMI Galaxy Survey and DYNAMO survey. For typical low-$z$ galaxies taken from the SAMI Galaxy Survey, we find the vertical velocity dispersion ($σ_{v, z}$) to be positively correlated with measures of star-formation rate, stellar mass, HI gas mass, and rotational velocity. The greatest correlation is with star-formation rate surface density ($Σ_\text{SFR}$). Using the total sample, we find $σ_{v, z}$ increases slowly as a function of integrated star-formation rate in the range SFR $\in$ [$10^{-3}$, 1] M$_\odot$ yr$^{-1}$ from $17\pm3$ km s$^{-1}$ to $24\pm5$ km s$^{-1}$ followed by a steeper increase up to $σ_{v, z}$ $\sim 80$ km s$^{-1}$ for SFR $\gtrsim 1$ M$_\odot$ yr$^{-1}$. This is consistent with recent theoretical models that suggest a $σ_{v, z}$ floor driven by star-formation feedback processes with an upturn in $σ_{v, z}$ at higher SFR driven by gravitational transport of gas through the disc.
In order to determine the causes of kinematic asymmetry in the H$α$ gas in the SAMI Galaxy Survey sample, we investigate the comparative influences of environment and intrinsic properties of galaxies on perturbation. We use spatially resolved H$α$ velocity fields from the SAMI Galaxy Survey to quantify kinematic asymmetry ($\overline{v_{asym}}$) in nearby galaxies and environmental and stellar mass data from the GAMA survey. {We find that local environment, measured as distance to nearest neighbour, is inversely correlated with kinematic asymmetry for galaxies with $\mathrm{\log(M_*/M_\odot)}>…
The combination of gas-phase oxygen abundances and stellar metallicities can provide us with unique insights into the metal enrichment histories of galaxies. In this work, we compare the stellar and gas-phase metallicities measured within a 1$R_{e}$ aperture for a representative sample of 472 star-forming galaxies extracted from the SAMI Galaxy Survey. We confirm that the stellar and interstellar medium (ISM) metallicities are strongly correlated, with scatter $\sim$3 times smaller than that found in previous works, and that integrated stellar populations are generally more metal-poor than the…
Misalignments between the rotation axis of stars and gas are an indication of external processes shaping galaxies throughout their evolution. Using observations of 3068 galaxies from the SAMI Galaxy Survey, we compute global kinematic position angles for 1445 objects with reliable kinematics and identify 169 (12%) galaxies which show stellar-gas misalignments. Kinematically decoupled features are more prevalent in early-type/passive galaxies compared to late-type/star-forming systems. Star formation is the main source of gas ionisation in only 22% of misaligned galaxies; 17% are Seyfert object…
We examine the kinematic morphology of early-type galaxies (ETGs) in eight galaxy clusters in the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. The clusters cover a mass range of 14.2<log(M_200/M_odot)<15.2 and we measure spatially-resolved stellar kinematics for 315 member galaxies with stellar masses 10.0<log(M_*/M_odot)<11.7 within 1R_200 of the cluster centers. We calculate the spin parameter, lambda_R and use that to classify the kinematic morphology of the galaxies as fast or slow rotators. The total fraction of slow rotators in the early-type galaxy populatio…
We study the internal radial gradients of the stellar populations in a sample comprising 522 early-type galaxies (ETGs) from the SAMI (Sydney- AAO Multi-object Integral field spectrograph) Galaxy Survey. We stack the spectra of individual spaxels in radial bins, and derive basic stellar population properties: total metallicity ([Z/H]), [Mg/Fe], [C/Fe] and age. The radial gradient ($\nabla$) and central value of the fits (evaluated at R$_e$/4) are compared against a set of six possible drivers of the trends. We find that velocity dispersion ($σ$) - or, equivalently gravitational potential - is …
We investigate the energy sources of random turbulent motions of ionised gas from H$α$ emission in eight local star-forming galaxies from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. These galaxies satisfy strict pure star-forming selection criteria to avoid contamination from active galactic nuclei (AGN) or strong shocks/outflows. Using the relatively high spatial and spectral resolution of SAMI, we find that -- on sub-kpc scales our galaxies display a flat distribution of ionised gas velocity dispersion as a function of star formation rate (SFR) surface densi…
The kinematic morphology-density relation of galaxies is normally attributed to a changing distribution of galaxy stellar masses with the local environment. However, earlier studies were largely focused on slow rotators; the dynamical properties of the overall population in relation to environment have received less attention. We use the SAMI Galaxy Survey to investigate the dynamical properties of $\sim$1800 early and late-type galaxies with $\log(M_*/M_{\odot})>9.5$ as a function of mean environmental overdensity ($Σ_{5}$) and their rank within a group or cluster. By classifying galaxies int…
The existence of a kinematic morphology-density relation remains uncertain, and instead stellar mass appears the more dominant driver of galaxy kinematics. We investigate the dependence of the stellar spin parameter proxy $λ_{R_e}$ on environment using a marked cross-correlation method with data from the SAMI Galaxy Survey. Our sample contains 710 galaxies with spatially resolved stellar velocity and velocity dispersion measurements. By utilising the highly complete spectroscopic data from the GAMA survey, we calculate marked cross-correlation functions for SAMI galaxies using a pair count est…
Misalignment of gas and stellar rotation in galaxies can give clues to the origin and processing of accreted gas. Integral field spectroscopic observations of 1213 galaxies from the SAMI Galaxy Survey show that 11% of galaxies with fitted gas and stellar rotation are misaligned by more than 30 degrees in both field/group and cluster environments. Using SAMI morphological classifications and Sersic indices, the misalignment fraction is 45+/-6% in early-type galaxies, but only 5+/-1% in late-type galaxies. The distribution of position angle offsets is used to test the physical drivers of this di…
We explore local and global dynamical differences between the kinematics of ionised gas and stars in a sample of galaxies from Data Release 3 of the SAMI Galaxy Survey. We find better agreement between local (i.e., comparing on a spaxel-to-spaxel basis) velocities and dispersion of gas and stars in younger systems as with previous work on the asymmetric drift in galaxies, suggesting that the dynamics of stars and ionised gas are initially coupled. The intrinsic scatter around the velocity and dispersion relations increases with increasing stellar age and mass, suggesting that subsequent mechan…
Neutral hydrogen (HI) velocity dispersions are believed to be set by turbulence in the interstellar medium (ISM). Although turbulence is widely believed to be driven by star formation (SF), recent studies have shown that this driving mechanism may not be dominant in regions of low SF rate surface density (SFRSD), such as found in dwarf galaxies or the outer regions of spirals. We have generated average HI line profiles in a number of nearby dwarfs and low-mass spirals by co-adding HI spectra in regions with either a common radius or SFRSD. We find that the spatially-resolved superprofiles are …
Supernova explosions inject a considerable amount of energy into the interstellar medium (ISM) in regions with high to moderate star formation rates. In order to assess whether the driving of turbulence by supernovae is also important in the outer Galactic disk, where the star formation rates are lower, we study the spatial distribution of molecular cloud (MC) inclinations with respect to the Galactic plane. The latter contains important information on the nature of the mechanism of energy injection into the ISM. We analyze the spatial correlations between the position angles (PAs) of a select…
We present the results of the Velocity Coordinate Spectrum (VCS) technique to calculate the velocity power spectrum of turbulence in the Small Magellanic Cloud (SMC) in 21cm emission. We have obtained a velocity spectral index of -3.85 and an injection scale of 2.3 kpc. The spectral index is steeper than the Kolmogorov index which is expected for shock-dominated turbulence which is in agreement with past works on the SMC gas dynamics. The injection scale of 2.3 kpc suggests that tidal interactions with the Large Magellanic Cloud are the dominate driver of turbulence in this dwarf galaxy. This …
We investigate what drives the redshift evolution of the typical electron density ($n_e$) in star-forming galaxies, using a sample of 140 galaxies drawn primarily from KMOS$^{\rm 3D}$ ($0.6\lesssim{z}\lesssim{2.6}$) and 471 galaxies from SAMI ($z<0.113$). We select galaxies that do not show evidence of AGN activity or outflows, to constrain the average conditions within H II regions. Measurements of the [SII]$λ$6716/[SII]$λ$6731 ratio in four redshift bins indicate that the local $n_e$ in the line-emitting material decreases from 187$^{+140}_{-132}$ cm$^{-3}$ at $z\sim$ 2.2 to 32$^{+4}_{-9}$ c…
Kinematics of H I and O VI Absorbers: Insights into the Turbulence Driver of the Multiphase Circumgalactic Medium
Tsinghua University（清华大学）；The University of Chicago（芝加哥大学）；Peking University（北京大学）；Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut（海德堡大学天文中心，天文计算研究所）
We analyse the velocity dispersion properties of 472 z~0.9 star-forming galaxies observed as part of the KMOS Redshift One Spectroscopic Survey (KROSS). The majority of this sample is rotationally dominated (83 +/- 5% with v_C/sigma_0 > 1) but also dynamically hot and highly turbulent. After correcting for beam smearing effects, the median intrinsic velocity dispersion for the final sample is sigma_0 = 43.2 +/- 0.8 km/s with a rotational velocity to dispersion ratio of v_C/sigma_0 = 2.6 +/- 0.1. To explore the relationship between velocity dispersion, stellar mass, star formation rate and reds…
Large-scale and local environmental drivers of quenching: tracing H$α$ concentration in X-ray and optical galaxy groups
The University of Sydney（悉尼大学）；ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（三维全天空天体物理学卓越研究中心）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Beijing Normal University（北京师范大学）；Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）
Two competing models, gravitational instability-driven transport and stellar feedback, have been proposed to interpret the high velocity dispersions observed in high-redshift galaxies. We study the major mechanisms to drive the turbulence in star-forming galaxies using a sample of galaxies from the xCOLD GASS survey, selected based on their star-formation rate (SFR) and gas fraction to be in the regime that can best distinguish between the proposed models. We perform Wide Field Spectrograph (WiFeS) integral field spectroscopic (IFS) observations to measure the intrinsic gas velocity dispersion…
Small scale turbulence alongside with large scale turbulence in a z=1.87 star Forming Galaxy with outflowing wind, revealed by Multi-point structure functions
We investigate the feedback of the stellar jets on the surrounding interstellar gas based on 2D and 3D simulations applying HD and MHD module of PLUTO 4.2 code. The main question we address is whether the stellar jet can be considered as a turbulence driver into the interstellar gas. In addition, we investigate the most effective circumstances in which the driven turbulence is larger and can survive for a longer time scale in the ambient gas. We present a case study of different parameters runs including the jet Mach number, the initial jet velocity field and the background magnetic field geom…
We test the hypothesis that the initial mass function (IMF) is determined by the density probability distribution function (PDF) produced by supersonic turbulence. We compare 14 simulations of star cluster formation in 50 solar mass molecular cloud cores where the initial turbulence contains either purely solenoidal or purely compressive modes, in each case resolving fragmentation to the opacity limit to determine the resultant IMF. We find statistically indistinguishable IMFs between the two sets of calculations, despite a factor of two difference in the star formation rate and in the standar…
Are supernovae driving turbulence in the solar neighborhood?
Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）；CEA（法国原子能和替代能源委员会）；CNRS（法国国家科学研究中心）；University of Vienna（维也纳大学）；ENS de Lyon（里昂高等师范学校）；Universite Claude Bernard Lyon 1（里昂第一大学）；Universität Heidelberg（海德堡大学）；Laboratoire de Physique de l’Ecole Normale Supérieure（巴黎高等师范学院物理实验室）；ENS（巴黎高等师范学院）；Université PSL（巴黎文理研究大学）；Sorbonne Université（索邦大学）；Observatoire de Paris（巴黎天文台）；INAF - Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所）；Università di Roma Tor Vergata（罗马托尔维加塔大学）
We revisit an alternate explanation for the turbulent nature of molecular clouds - namely, that velocity dispersions matching classical predictions of driven turbulence can be generated by the passage of clumpy material through a shock. While previous work suggested this mechanism can reproduce the observed Larson relation between velocity dispersion and size scale ($σ\propto L^Γ$ with $Γ\approx 0.5$), the effects of self-gravity and magnetic fields were not considered. We run a series of smoothed particle magnetohydrodynamics experiments, passing clumpy gas through a shock in the presence of …
We study the driving of turbulence in star-froming disc galaxies of different masses at different epochs, using an analytic "bathtub" model. The disc of gas and stars is assumed to be in marginal Toomre instability. Turbulence is assumed to be sustained via an energy balance between its dissipation and three simultaneous energy sources. These are stellar feedback, inward transport due to disc instability and clumpy accretion via streams. The transport rate is computed with two different formalisms, with similar results. To achieve the energy balance, the disc self-regulates either the mass fra…
Supermassive black holes (SMBHs) are thought to provide energy that prevents catastrophic cooling in the centers of massive galaxies and galaxy clusters. However, it remains unclear how this "feedback" process operates. We use high-resolution optical data to study the kinematics of multi-phase filamentary structures by measuring the velocity structure function (VSF) of the filaments over a wide range of scales in the centers of three nearby galaxy clusters: Perseus, Abell 2597 and Virgo. We find that the motions of the filaments are turbulent in all three clusters studied. There is a clear cor…
We study the shapes of spatially integrated H I emission-line profiles of galaxies in the EAGLE simulation using three separate measures of the profile's asymmetry. We show that the subset of EAGLE galaxies whose gas fractions and stellar masses are consistent with those in the xGASS survey also have similar H I line asymmetries. Central galaxies with symmetric H I line profiles typically correspond to rotationally supported H I and stellar disks, but those with asymmetric line profiles may or may not correspond to dispersion-dominated systems. Galaxies with symmetric H I emission lines are, o…
It is well known that gas in galaxy discs is highly turbulent, but there is much debate on which mechanism can energetically maintain this turbulence. Among the possible candidates, supernova (SN) explosions are likely the primary drivers but doubts remain on whether they can be sufficient in regions of moderate star formation activity, in particular in the outer parts of discs. In this paper, we measure the SN efficiency $η$, namely the fraction of the total SN energy needed to sustain turbulence in galaxies, and verify that SNe can indeed be the sole driving mechanism. The key novelty of our…
We review recent advances in the analytical and numerical modeling of the star formation rate in molecular clouds and discuss the available observational constraints. We focus on molecular clouds as the fundamental star formation sites, rather than on the larger-scale processes that form the clouds and set their properties. Molecular clouds are shaped into a complex filamentary structure by supersonic turbulence, with only a small fraction of the cloud mass channeled into collapsing protostars over a free-fall time of the system. In recent years, the physics of supersonic turbulence has been w…
Low-energy cosmic rays, in particular protons with energies below 1 GeV, are significant drivers of the thermochemistry of molecular clouds. However, these cosmic rays are also greatly impacted by energy losses and magnetic field transport effects in molecular gas. Explaining cosmic ray ionization rates of $10^{-16}$ s$^{-1}$ or greater in dense gas requires either a high external cosmic ray flux, or local sources of MeV-GeV cosmic ray protons. We present a new local source of low-energy cosmic rays in molecular clouds: first order Fermi-acceleration of protons in regions undergoing turbulent …
Molecular clouds in the central molecular zone (CMZ) have been observed to feature turbulent line widths that are significantly higher, and scale with cloud size more steeply, than in the rest of the Milky Way. In the same Galactic region, the stellar density is also much higher than in the rest of the Milky Way, and the vertical stellar velocity dispersion is large, meaning that even young stars are likely to cross the entire vertical extent of the CMZ within their lifetimes. Here, we investigate whether interactions of CMZ molecular clouds with crossing stars can account for the extraordinar…
The origin of non-thermal motions in massive star forming regions can be ascribed to turbulence acting against the gravitational collapse, or to the self-gravity itself driving the rapid global collapse. The dependence between velocity dispersion, radius and clouds surface density found by Heyer et al. (2009), $σ/R^{1/2}\propto Σ^{1/2}$, has been interpreted in terms of global collapse of clouds. In this work we demonstrate that this relation is an expression of a more general relation between accelerations. We introduce the gravo-turbulent acceleration, a$_k$, which describe the non-thermal m…
High spatial and spectral resolution observations of star formation and kinematics in early galaxies have shown that two-thirds are massive rotating disk galaxies with the remainder being less massive non-rotating objects. The line of sight averaged velocity dispersions are typically five times higher than in today's disk galaxies. This has suggested that gravitationally-unstable, gas-rich disks in the early Universe are fuelled by cold, dense accreting gas flowing along cosmic filaments and penetrating hot galactic gas halos. However these accreting flows have not been observed, and cosmic ac…
We explore what dominant physical mechanism sets the kinetic energy contained in neutral, atomic (HI) gas. We compare the HI line widths predicted from turbulence driven by supernova (SN) explosions and magneto-rotational instability (MRI) to direct observations in 11 disk galaxies. We use high-quality maps of the HI mass surface density and line width, obtained by the THINGS survey. We show that all sample galaxies exhibit a systematic radial decline in the HI line width, which appears to be a generic property of HI disks and also implies a radial decline in kinetic energy density of HI. At a…
Using JCMT Gould Belt Survey data from CO J=3-2 isotopologues, we present a meta-analysis of the outflows and energetics of star-forming regions in several Gould Belt clouds. The majority of the regions are strongly gravitationally bound. There is evidence that molecular outflows transport large quantities of momentum and energy. Outflow energies are at least 20 per cent of the total turbulent kinetic energies in all of the regions studied and greater than the turbulent energy in half of the regions. However, we find no evidence that outflows increase levels of turbulence, and there is no corr…
The formation of stars from gas drives the evolution of galaxies. Yet, it remains one of the hardest processes to understand when trying to connect observations of stellar and galaxy populations to models of large scale structure formation. The star formation rate at redshifts z > 2 drops off rather more quickly than was thought even five years ago. Theoretical models have tended to overpredict the star formation rate at these high redshifts substantially, primarily due to overcooling. Overcooling in galaxies typically occurs because of unphysical radiative cooling. As a result, insufficient t…
Bulk vs. turbulent motions at the centres of galaxy clusters: AGN-driven turbulence according to TNG-Cluster
Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Fakultät für Physik und Astronomie, Universität Heidelberg（海德堡大学物理与天文学院）；Département de Physique, Université de Montréal（蒙特利尔大学物理系）；Universität Heidelberg, Zentrum für Astronomie, ITA（海德堡大学天文学中心）；Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen（海德堡大学跨学科科学计算中心）
Turbulence in the interstellar medium (ISM) is crucial in the process of star formation. Shocks produced by supernova explosions, jets, radiation from massive stars, or galactic spiral-arm dynamics are amongst the most common drivers of turbulence in the ISM. However, it is not fully understood how shocks drive turbulence, in particular whether shock driving is a more solenoidal(rotational, divergence-free) or a more compressive (potential, curl-free) mode of driving turbulence. The mode of turbulence driving has profound consequences for star formation, with compressive driving producing thre…
We analyze age-velocity dispersion relations (AVRs) from kinematics of individual stars in eight Local Group galaxies ranging in mass from Carina ($M_{*} \sim 10^{6}$) to M31 ($M_{*} \sim 10^{11}$). Observationally the $σ$ vs. stellar age trends can be interpreted as dynamical heating of the stars by GMCs, bars/spiral arms, or merging subhalos; alternatively the stars could have simply been born out of a more turbulent ISM at high redshift and retain that larger velocity dispersion till present day - consistent with recent IFU studies. To ascertain the dominant mechanism and better understand …
Jet-driven shocks and turbulence in radio-loud Active Galactic Nuclei observed with JWST MIRI/MRS
Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家研究委员会-国家航空航天技术研究所）；Departamento de Física, CCNE, Universidade Federal de Santa Maria（圣玛丽亚联邦大学物理系，CCNE）；Instituto de Astrofísica de Canarias（加那利群岛天体物理学研究所）；Universidad de La Laguna（拉帕鲁纳大学）；National and Kapodistrian University of Athens（雅典国立卡波季斯特里安大学）；Sorbonne Université（索邦大学）；University of Utah（犹他大学）
The driving mode of turbulence in disc galaxy simulations with adaptive mesh refinement
Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Lund Observatory, Division of Astrophysics, Department of Physics, Lund University（隆德大学物理系天体物理学部隆德天文台）
The dynamics of the intracluster medium (ICM) is affected by turbulence driven by several processes, such as mergers, accretion and feedback from active galactic nuclei. X-ray surface brightness fluctuations have been used to constrain turbulence in galaxy clusters. Here, we use simulations to further investigate the relation between gas density and turbulent velocity fluctuations, with a focus on the effect of the stratification of the ICM. In this work, we studied the turbulence driven by hierarchical accretion by analysing a sample of galaxy clusters simulated with the cosmological code ENZ…
Evidence for the gravity-driven and magnetically-regularized gas flows feeding the massive protostellar cluster in Cepheus A
Indian Institute of Science Education and Research Tirupati（印度科学教育研究所蒂鲁帕蒂分校）；Indian Institute of Science Education and Research (IISER) Mohali（印度科学教育研究所莫哈利分校）；Tsinghua University（清华大学）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）；Academia Sinica Institute of Astronomy & Astrophysics（中央研究院天文及天文物理研究所）；Physical Research Laboratory (PRL)（物理研究实验室）；East Asian Observatory（东亚天文台）；National Tsing Hua University（国立清华大学）
Revealing the nature of the starburst galaxies in the $z=2.4$ overdensity HATLAS J0849
Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天体物理与天文研究学院）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间研究中心）；DARK, Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所DARK中心）；Max-Planck-Institut für Extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study The University of Tokyo（东京大学宇宙起源研究科 Kavli 宇宙物质与物理全球卓越中心）；Sub-department of Astrophysics, Department of Physics, University of Oxford（牛津大学物理系天体物理小组）
Models for cosmic ray (CR) dynamics fundamentally depend on the rate of CR scattering from magnetic fluctuations. In the ISM, for CRs with energies ~MeV-TeV, these fluctuations are usually attributed either to 'extrinsic turbulence' (ET) - a cascade from larger scales - or 'self-confinement' (SC) - self-generated fluctuations from CR streaming. Using simple analytic arguments and detailed live numerical CR transport calculations in galaxy simulations, we show that both of these, in standard form, cannot explain even basic qualitative features of observed CR spectra. For ET, any spectrum that o…
We investigate giant molecular cloud (GMCs) collisions and their ability to induce gravitational instability and thus star formation. This mechanism may be a major driver of star formation activity in galactic disks. We carry out a series of three dimensional, magnetohydrodynamics (MHD), adaptive mesh refinement (AMR) simulations to study how cloud collisions trigger formation of dense filaments and clumps. Heating and cooling functions are implemented based on photo-dissociation region (PDR) models that span the atomic to molecular transition and can return detailed diagnostic information. Th…
We present an overview of the Middle Ages Galaxy Properties with Integral Field Spectroscopy (MAGPI) survey, a Large Program on ESO/VLT. MAGPI is designed to study the physical drivers of galaxy transformation at a lookback time of 3-4 Gyr, during which the dynamical, morphological, and chemical properties of galaxies are predicted to evolve significantly. The survey uses new medium-deep adaptive optics aided MUSE observations of fields selected from the GAMA survey, providing a wealth of publicly available ancillary multi-wavelength data. With these data, MAGPI will map the kinematic and chem…
