Cluster galaxies moving through the intracluster medium (ICM) are expected to lose some of their interstellar medium (ISM) through ISM-ICM interactions. We perform high resolution (40 pc) three-dimensional hydrodynamical simulations of a galaxy undergoing ram pressure stripping including radiative cooling in order to investigate stripping of a multiphase medium. The clumpy, multiphase ISM is self-consistently produced by the inclusion of radiative cooling, and spans six orders of magnitude in gas density. We find no large variations in the amount of gas lost whether or not cooling is involved, although the gas in the multiphase galaxy is stripped more quickly and to a smaller radius. We also see significant differences in the morphology of the stripped disks. This occurs because the multiphase medium naturally includes high density clouds set inside regions of lower density. We find that the lower density gas is stripped quickly from any radius of the galaxy, and the higher density gas can then be ablated. If high density clouds survive, through interaction with the ICM they lose enough angular momentum to drift towards the center of the galaxy where they are no longer stripped. Finally, we find that low ram pressure values compress gas into high density clouds that could lead to enhanced star formation, while high ram pressure leads to a smaller amount of high-density gas.
Ram pressure stripping of the multiphase ISM is studied in the perturbed Virgo cluster spiral galaxy NGC 4438. This galaxy underwent a tidal interaction ~100 Myr ago and is now strongly affected by ram pressure stripping. Deep VLA radio continuum observations at 6 and 20 cm are presented. We detect prominent extraplanar emission to the west of the galactic center, which extends twice as far as the other tracers of extraplanar material. The spectral index of the extraplanar emission does not steepen with increasing distance from the galaxy. This implies in situ re-acceleration of relativistic e…
Using the IllustrisTNG simulation, we study the interaction of large-scale shocks with the circumgalactic medium (CGM) and interstellar medium (ISM) of star-forming (SF) satellite galaxies in galaxy clusters. These shocks are usually produced by mergers and massive accretion. Our visual inspection shows that approximately half of SF satellites have encountered shocks in their host clusters at $z\leq0.11$. After a satellite crosses a shock front and enters the postshock region, the ram pressure on it is boosted significantly. Both the CGM and ISM can be severely impacted, either by striping or …
Ram pressure stripping (RPS) is a process that removes the interstellar medium (ISM) quickly, playing a vital role in galaxy evolution. Previous RPS studies have treated the ISM as single-phase or lack the resolution and physical processes to properly capture the full multiphase ISM. To improve this simplification, we introduce an inflowing, hot intracluster medium (ICM) into a self-consistently modeled ISM in a local patch of star-forming galactic disks using the TIGRESS framework. Our simulations reveal that the workings of RPS are not only direct acceleration of the ISM by ICM ram pressure …
The Launching of Galactic Winds from a Multiphase ISM
Max Planck Institute for Astrophysics（马普天体物理研究所）；Astronomisches Rechen-Institut, Zentrum für Astronomie, Universität Heidelberg（海德堡大学天文学计算研究所）；Hamburger Sternwarte, Universität Hamburg（汉堡大学天文台）
Remarkable dust extinction features in the deep HST V and I images of the face-on Coma cluster spiral galaxy NGC 4921 show in unprecedented ways how ram pressure strips the ISM from the disk of a spiral galaxy. New VLA HI maps show a truncated and highly asymmetric HI disk with a compressed HI distribution in the NW, providing evidence for ram pressure acting from the NW. Where the HI distribution is truncated in the NW region, HST images show a well-defined, continuous front of dust that extends over 90 degrees and 20 kpc. This dust front separates the dusty from dust-free regions of the gala…
Pressure balance plays a central role in models of the interstellar medium (ISM), but whether and how pressure balance is realized in a realistic multiphase ISM is not yet well understood. We address this question using a set of FIRE-2 cosmological zoom-in simulations of Milky Way-mass disk galaxies, in which a multiphase ISM is self-consistently shaped by gravity, cooling, and stellar feedback. We analyze how gravity determines the vertical pressure profile as well as how the total ISM pressure is partitioned between different phases and components (thermal, dispersion/turbulence, and bulk fl…
We study gas inflows onto supermassive black holes using hydrodynamics simulations of isolated galaxies and idealized galaxy mergers with an explicit, multiphase interstellar medium (ISM). Our simulations use the recently developed ISM and stellar evolution model called Stars and MUltiphase Gas in GaLaxiEs (SMUGGLE). We implement a novel super-Lagrangian refinement scheme that increases the gas mass resolution in the immediate neighborhood of the black holes (BHs) to accurately resolve gas accretion. We do not include black hole feedback in our simulations. We find that the complex and turbule…
We investigate the effects of magnetic fields and turbulence on ram pressure stripping in elliptical galaxies using ideal magnetohydrodynamics simulations. We consider weakly-magnetised interstellar medium (ISM) characterised by subsonic turbulence, and two orientations of the magnetic fields in the intracluster medium (ICM) - parallel and perpendicular to the direction of the galaxy motion through the ICM. While the stronger turbulence enhances the ram pressure stripping mass loss, the magnetic fields tend to suppress the stripping rates, and the suppression is stronger for parallel fields. H…
Ram pressure stripping (RPS) is known to be a key environmental effect that can remove interstellar gas from galaxies in a cluster. The RPS process is commonly described as a competition between the ram pressure by the intracluster medium (ICM) and the anchoring pressure on the interstellar medium (ISM) by the gravitational potential of a galaxy. However, the actual gas stripping process can be more complicated due to the complexity of gas physics such as compression and geometrical self-shielding as well as cooling and heating. In order to verify how well the observed signatures of the RPS pr…
The atomic multiphase interstellar medium of galaxies in the COLIBRE simulations
University of Vienna（维也纳大学）；Leiden University（莱顿大学）；Università degli Studi di Milano-Bicocca（米兰比可卡大学）；University of Durham（杜伦大学）；University of Hull（赫尔大学）；University of Hertfordshire（赫特福德大学）
The sensitive infrared telescopes, Spitzer and Herschel, have been used to target low-metallicity star-forming galaxies, allowing us to investigate the properties of their interstellar medium (ISM) in unprecedented detail. Interpretation of the observations in physical terms relies on careful modeling of those properties. We have employed a multiphase approach to model the ISM phases (HII region and photodissociation region) with the spectral synthesis code Cloudy. Our goal is to characterize the physical conditions (gas densities, radiation fields, etc.) in the ISM of the galaxies from the He…
Up, Up, and Away? Quantifying ISM Fallback using Ram Pressure Stripping Simulations
Center for Computational Astrophysics, Flatiron Institute（Flatiron Institute 计算天体物理学中心）；Department of Astronomy, Yale University（耶鲁大学天文学系）；Department of Astronomy, Columbia University（哥伦比亚大学天文学系）
Galactic Dust Polarization in Turbulent Multiphase ISM: On the Origin of the $EE/BB$ Asymmetry
Institute for Advanced Study（高等研究院）；California Institute of Technology（加州理工学院）；Korea Astronomy and Space Science Institute（韩国天文学与宇宙学研究所）；Korea University of Science and Technology（韩国科学技术院）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）
We develop a model of dust evolution in a multiphase, inhomogeneous ISM including dust growth and destruction processes. The physical conditions for grain evolution are taken from hydrodynamical simulations of giant molecular clouds in a Milky Way-like spiral galaxy. We improve the treatment of dust growth by accretion in the ISM to investigate the role of the temperature-dependent sticking coefficient and ion-grain interactions. From detailed observational data on the gas-phase Si abundances [Si/H]_{gas} measured in the local Galaxy, we derive a relation between the average [Si/H]_{gas} and t…
Supersonic turbulence in the interstellar medium (ISM) is believed to decay rapidly within a flow crossing time irrespective of the degree of magnetization. However, this general consensus of decaying magnetohydrodynamic (MHD) turbulence relies on local isothermal simulations, which are unable to take into account the roles of global structures of magnetic fields and the ISM. Utilizing three-dimensional MHD simulations including interstellar cooling and heating, we investigate decaying MHD turbulence within cold neutral medium sheets embedded in warm neutral medium. Early evolution of turbulen…
Massive, young stars are the main source of energy that maintains multiphase structure and turbulence in the interstellar medium (ISM), and without this "feedback" the star formation rate (SFR) would be much higher than is observed. Rapid energy loss in the ISM and efficient energy recovery by stellar feedback lead to co-regulation of SFRs and the ISM state. Realistic approaches to this problem should solve the dynamical evolution of the ISM, including star formation, and the input of feedback energy self-consistently and accurately. Here, we present the TIGRESS-NCR numerical framework, in whi…
The cluster environment can affect galaxy evolution in different ways: via ram pressure stripping or by gravitational perturbations caused by galactic encounters. New IRAM 30m HERA CO(2-1) data of NGC 4501 and NGC 4567/68 are presented. We find an increase in the molecular fraction where the ISM is compressed. The gas is close to self-gravitation in compressed regions. This leads to an increase in gas pressure and a decrease in the ratio between the molecular fraction and total ISM pressure. The overall Kennicutt Schmidt relation based on a pixel-by-pixel analysis at ~1.5 kpc resolution is not…
The physics of magnetic fields ($\textbf{B}$) and cosmic rays (CRs) have recently been included in simulations of galaxy formation. However, significant uncertainties remain in how these components affect galaxy evolution. To understand their common observational tracers, we analyze the magnetic fields in a set of high-resolution, magneto-hydrodynamic, cosmological simulations of Milky-Way-like galaxies from the FIRE-2 project. We compare mock observables of magnetic field tracers for simulations with and without CRs to observations of Zeeman splitting and rotation/dispersion measures. We find…
Multiphase turbulence as the origin of OH+, H2O+ and H3+ column density scatter in the local ISM
Technion Israel Institute of Technology（以色列理工学院）；The Johns Hopkins University（约翰斯·霍普金斯大学）；Rutgers, The State University of New Jersey（新泽西州立罗格斯大学）；Center for Computational Astrophysics, Flatiron Institute, Simons Foundation（西蒙斯基金会平顿研究所计算天体物理学中心）
In this paper we show results of numerical simulations for the turbulence in the interstellar medium. These results were obtained using a Riemann solver-free numerical scheme for high-Mach number hyperbolic equations. Here we especially concentrate on the physical properties of the ISM. That is, we do not present turbulence simulations trimmed to be applicable to the interstellar medium. The simulations are rather based on physical estimates for the relevant parameters of the interstellar gas. Applying our code to simulate the turbulent plasma motion within a typical interstellar molecular clo…
Galactic outflows produced by stellar feedback are known to be multiphase in nature. Both observations and simulations indicate that the material within several kpc of galactic disk mid-planes consists of warm clouds embedded within a hot wind. A theoretical understanding of the outflow phenomenon, including both winds and fountain flows, requires study of the interactions among thermal phases. We develop a method to quantify these interactions via measurements of mass, momentum, and energy flux exchanges using temporally and spatially averaged quantities and conservation laws. We apply this m…
CO(J=1-0) line emission is a widely used observational tracer of molecular gas, rendering essential the X_CO factor, which is applied to convert CO luminosity to H_2 mass. We use numerical simulations to study how X_CO depends on numerical resolution, non-steady-state chemistry, physical environment, and observational beam size. Our study employs 3D magnetohydrodynamics (MHD) simulations of galactic disks with solar neighborhood conditions, where star formation and the three-phase interstellar medium (ISM) are self-consistently regulated by gravity and stellar feedback. Synthetic CO maps are o…
Magnetic fields grow quickly, even at early cosmological times, suggesting the action of a small-scale dynamo (SSD) in the interstellar medium (ISM) of galaxies. Many studies have focused on idealized, isotropic, homogeneous, turbulent driving of the SSD. Here we analyze more realistic simulations of supernova-driven turbulence to understand how it drives an SSD. We find that SSD growth rates are intermittently variable as a result of the evolving multiphase ISM structure. Rapid growth in the magnetic field typically occurs in hot gas, with the highest overall growth rates occurring when the f…
Hydrodynamical simulations show that the ram-pressure stripping in galaxy clusters fosters a strong interaction between stripped interstellar medium (ISM) and the surrounding medium, with the possibility of intracluster medium (ICM) cooling into cold gas clouds. Exploiting the MUSE observation of three jellyfish galaxies from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we explore the gas metallicity of star-forming clumps in their gas tails. We find that the oxygen abundance of the stripped gas decreases as a function of the distance from the parent galaxy disk; the observ…
Ratios of polycyclic aromatic hydrocarbon (PAH) vibrational bands are a promising tool for measuring the properties of the PAH population and their effect on star formation. The photometric bands of the MIRI and NIRCam instruments on JWST provide the opportunity to measure PAH emission features across entire galaxy disks at unprecedented resolution and sensitivity. Here we present the first results of this analysis in a sample of three nearby galaxies: NGC 628, NGC 1365, and NGC 7496. Based on the variations observed in the 3.3, 7.7, and 11.3 $μ$m features, we infer changes to the average PAH …
We present simulations of galaxy formation, based on the GADGET-3 code, in which a sub-resolution model for star formation and stellar feedback is interfaced with a new model for AGN feedback. Our sub-resolution model describes a multiphase ISM, accounting for hot and cold gas within the same resolution element: we exploit this feature to investigate the impact of coupling AGN feedback energy to the different phases of the ISM over cosmic time. Our fiducial model considers that AGN feedback energy coupling is driven by the covering factors of the hot and cold phases. We perform a suite of cosm…
We systematically perform hydrodynamics simulations of 20 km s^-1 converging flows of the warm neutral medium (WNM) to calculate the formation of the cold neutral medium (CNM), especially focusing on the mean properties of the multiphase interstellar medium (ISM), such as the average shock front position and the mean density on a 10 pc scale. Our results show that the convergence in those mean properties requires 0.02 pc spatial resolution that resolves the cooling length of the thermally unstable neutral medium (UNM) to follow the dynamical condensation from the WNM to CNM. We also find that …
We introduce the PRISM interstellar medium (ISM) model for thermochemistry and its implementation in the RAMSES-RTZ code. The model includes a non-equilibrium primordial, metal, and molecular chemistry network for 115 species coupled to on-the-fly multifrequency radiation transport. PRISM accurately accounts for the dominant ISM cooling and heating processes in the low-density regime (i.e. $ρ<10^5\ {\rm cm^{-3}}$), including photoheating, photoelectric heating, H$_2$ heating/cooling, cosmic-ray heating, H/He cooling, metal-line cooling, CO cooling, and dust cooling (recombination and gas-grain…
We use numerical simulations to analyze the evolution and properties of superbubbles (SBs), driven by multiple supernovae (SNe), that propagate into the two-phase (warm/cold), cloudy interstellar medium (ISM). We consider a range of mean background densities n_avg=0.1-10 cm^{-3} and intervals between SNe dt_sn=0.01-1 Myr, and follow each SB until the radius reaches (1-2)H, where H is the characteristic ISM disk thickness. Except for embedded dense clouds, each SB is hot until a time t_sf,m when the shocked warm gas at the outer front cools and forms an overdense shell. Subsequently, diffuse ga…
Ultrafast outflows (UFOs) from supermassive black holes (SMBHs) are thought to regulate the growth of SMBHs and host galaxies, resulting in a number of observational correlations. We present high-resolution numerical simulations of the impact of a thermalized UFO on the ambient gas in the inner part of the host galaxy. Our results depend strongly on whether the gas is homogeneous or clumpy. In the former case all of the ambient gas is driven outward rapidly as expected based on commonly used energy budget arguments, while in the latter the flows of mass and energy decouple. Carrying most of th…
It has been hypothesized that photons from young, massive star clusters are responsible for maintaining the ionization of diffuse warm ionized gas seen in both the Milky Way and other disk galaxies. For a theoretical investigation of the warm ionized medium (WIM), it is crucial to solve radiation transfer equations where the ISM and clusters are modeled self-consistently. To this end, we employ a Solar neighborhood model of TIGRESS, a magnetohydrodynamic simulation of the multiphase, star-forming ISM, and post-process the simulation with an adaptive ray tracing method to transfer UV radiation …
Galaxy evolution and star formation are two multi-scale problems tightly linked to each other. To understand the interstellar cycle, which triggers galaxy evolution, it is necessary to describe simultaneously the large-scale evolution widely induced by the feedback processes and the details of the gas dynamics that controls the star formation process through gravitational collapse. We perform a set of three-dimensional high-resolution numerical simulations of a turbulent, self-gravitating and magnetized interstellar medium within a $1\ \mathrm{kpc}$ stratified box with supernova feedback corre…
We present a multi-wavelength study of a nearby radio loud elliptical galaxy NGC708, selected from the Bologna B2 sample of radio galaxies. We obtained optical broad band and narrow images from IGO 2m telescope (Pune, India). We supplement the multi-wavelength coverage of the observation by using X-ray data from Chandra, infrared data from 2MASS, Spitzer and WISE and optical image from DSS and HST. In order to investigate properties of interstellar medium, we have generated unsharp-masked, color, residual, quotient, dust extinction, H_alph emission maps. From the derived maps it is evident tha…
The removal of the interstellar medium (ISM) of disk galaxies through ram pressure stripping (RPS) has been extensively studied in numerous simulations. Nevertheless, the role of magnetic fields (MF) on the gas dynamics in this process has been hardly studied, although the MF influence on the large-scale disk structure is well established. With this in mind, we present a 3D magnetohydrodynamic (MHD) simulation of face-on RPS of a disk galaxy to study the impact of the galactic MF in the gas stripping. The main effect of including a galactic MF is a flared disk. When the intracluster medium (IC…
Galactic outflows have density, temperature, and velocity variations at least as large as that of the multiphase, turbulent interstellar medium (ISM) from which they originate. We have conducted a suite of parsec-resolution numerical simulations using the TIGRESS framework, in which outflows emerge as a consequence of interaction between supernovae (SNe) and the star-forming ISM. The outflowing gas is characterized by two distinct thermal phases, cool (T<10^4 K) and hot (T>10^6 K), with most mass carried by the cool phase and most energy and newly-injected metals carried by the hot phase. Both…
Molecular clouds are essentially made up of atomic and molecular hydrogen, which in spite of being the simplest molecule in the ISM plays a key role in the chemical evolution of molecular clouds. Since its formation time is very long, the H2 molecules can be transported by the turbulent motions within the cloud toward low density and warm regions, where its enhanced abundance can boost the abundances of molecules with high endothermicities. We present high resolution simulations where we include the evolution of the molecular gas under the effect of the dynamics, and we analyze its impact on t…
The energy and momentum feedback from young stars has a profound impact on the interstellar medium (ISM), including heating and driving turbulence in the neutral gas that fuels future star formation. Recent theory has argued that this leads to a quasi-equilibrium self-regulated state, and for outer atomic-dominated disks results in the surface density of star formation $Σ_{SFR}$ varying approximately linearly with the weight of the ISM (or midplane turbulent + thermal pressure). We use three-dimensional numerical hydrodynamic simulations to test the theoretical predictions for thermal, turbule…
We describe and constrain the origins of ISM structures likely created by ongoing ICM ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and NGC 4402, using HST BVI images of dust extinction and stars, as well as supplementary HI, Halpha, and radio continuum images. This is the highest-resolution study to date of the physical processes that occur during an ICM-ISM ram pressure stripping interaction, ram pressure stripping's effects on the multi-phase, multi-density ISM, and the formation and evolution of ram-pressure-stripped tails. In dust extinction, we view the leading side of NG…
We report the first detection of multiphase gas within a quiescent galaxy beyond $z\approx0$. The observations use the brighter image of doubly lensed QSO HE 0047$-$1756 to probe the ISM of the massive ($M_{\rm star}\approx 10^{11} \mathrm{M_\odot}$) elliptical lens galaxy at $z_\mathrm{gal}=0.408$. Using Hubble Space Telescope's Cosmic Origins Spectrograph (COS), we obtain a medium-resolution FUV spectrum of the lensed QSO and identify numerous absorption features from $\mathrm{H_2}$ in the lens ISM at projected distance $d=4.6$ kpc. The $\mathrm{H_2}$ column density is $\log N(\mathrm{H_2})/…
X-ray studies of jellyfish galaxies play a crucial role in understanding the interactions between the interstellar medium (ISM) and the intracluster medium (ICM). In this paper, we focused on the jellyfish galaxy JO201. By combining archival Chandra observations, MUSE H$α$ cubes, and maps of the emission fraction of the diffuse ionised gas, we investigated both its high energy spectral properties and the spatial correlation between its X-ray and optical emissions. The X-ray emission of JO201 is provided by both the Compton thick AGN (L$_{\text{X}}^{0.5-10 \text{keV}}$=2.7$\cdot$10$^{41}$ erg s…
We report the detection of CO emission in the recently discovered multiphase isolated gas cloud in the nearby galaxy cluster Abell 1367. The cloud is located about 800 kpc in projection from the center of the cluster and at a projected distance of > 80 kpc from any galaxy. It is the first and the only known isolated intra-cluster cloud detected in X-ray, H$α$, and CO emission. We found a total of about $2.2\times 10^8 M_\odot$ of H$_2$ with the IRAM 30-m telescope in two regions, one associated with the peak of H$α$ emission and another with the peak of X-ray emission surrounded by weak H$α$ f…
We present an efficient heating/cooling method coupled with chemistry and ultraviolet (UV) radiative transfer, which can be applied to numerical simulations of the interstellar medium (ISM). We follow the time-dependent evolution of hydrogen species (H$_2$, H, H$^+$), assume carbon/oxygen species (C, C$^+$, CO, O, and O$^+$) are in formation-destruction balance given the non-steady hydrogen abundances, and include essential heating/cooling processes needed to capture thermodynamics of all ISM phases. UV radiation from discrete point sources and the diffuse background is followed through adapti…
Context. Massive star-formation leads to enrichment with heavy elements of the interstellar medium. On the other hand, the abundance of heavy elements is a key parameter to study the star-formation history of galaxies. Furthermore, the total molecular hydrogen mass, usually determined by converting CO or [C ii] 158 $μ$m luminosities, depends on the metallicity as well. The excitation of metallicity-sensitive emission lines, however, depends on the gas density of H ii regions, where they arise. Aims. We used spectroscopic observations from SOFIA, Herschel, and Spitzer of the nuclear region of t…
