Ram Pressure Stripping Of Gas Research Articles

Ram-pressure Stripping of a Kicked Hill Sphere: Prompt Electromagnetic Emission from the Merger of Stellar Mass Black Holes in an AGN Accretion Disk

Abstract Accretion disks around supermassive black holes (SMBHs) are promising sites for stellar mass black hole (BH) mergers due to mass segregation and merger acceleration by disk gas torques. Here we show that a gravitational-wave (GW) kick at BH merger causes ram-pressure stripping of gas within the BH Hill sphere. If R H ≥ H, the disk height, an off-center UV flare at a BH ∼ 103 r g , emerges within t UV ∼ O(2 days)(a BH/103 r g )(M SMBH/108 M ⊙)(v kick/102 km s−1) postmerger and lasts O(R H/v kick) ∼ O(5t UV). The flare emerges with luminosity O(1042erg s−1)(t UV/2days)−1(M Hill/1M ⊙)(v kick/102 km s−1)2. Active galactic nucleus optical/UV photometry is altered and asymmetric broad emission line profiles can develop after weeks. If R H < H, detectability depends on disk optical depth. Follow-up by large optical sky surveys is optimized for small GW error volumes and for Laser Interferometer Gravitational-Wave Observatory/Virgo triggers >50M ⊙.

The influence of mergers and ram-pressure stripping on black hole–bulge correlations

We analyse the scatter in the correlation between super-massive black hole (SMBH) mass and bulge stellar mass of the host galaxy, and infer that it cannot be accounted for by mergers alone. The merger-only scenario, where small galaxies merge to establish a proportionality relation between the SMBH and bulge masses, leads to a scatter around the linear proportionality line that increases with the square root of the SMBH (or bulge) mass. By examining a sample of 103 galaxies we find that the intrinsic scatter increases more rapidly than expected from the merger-only scenario. The correlation between SMBH masses and their host galaxy properties is therefore more likely to be determined by a negative feedback mechanism that is driven by an active galactic nucleus. We find a hint that some galaxies with missing stellar mass reside close to the centre of clusters and speculate that ram-pressure stripping of gas off the young galaxy as it moves near the cluster centre, might explain the missing stellar mass at later times.

Optical and X-ray profiles in the REXCESS sample of galaxy clusters*

Galaxy clusters' structure, dominated by dark matter, is traced by member galaxies in the optical and hot intra-cluster medium (ICM) in X-rays. We compare the radial distribution of these components and determine the mass-to-light ratio vs. system mass relation. We use 14 clusters from the REXCESS sample which is representative of clusters detected in X-ray surveys. Photometric observations with the Wide Field Imager on the 2.2m MPG/ESO telescope are used to determine the number density profiles of the galaxy distribution out to $r_{200}$. These are compared to electron density profiles of the ICM obtained using XMM-Newton, and dark matter profiles inferred from scaling relations and an NFW model. While red sequence galaxies trace the total matter profile, the blue galaxy distribution is much shallower. We see a deficit of faint galaxies in the central regions of massive and regular clusters, and strong suppression of bright and faint blue galaxies in the centres of cool-core clusters, attributable to ram pressure stripping of gas from blue galaxies in high density regions of ICM and disruption of faint galaxies due to galaxy interactions. We find a mass-to-light ratio vs. mass relation within $r_{200}$ of $\left(3.0\pm0.4\right) \times 10^2\, h\,\mathrm{M}_{\odot}\,\mathrm{L}_{\odot}^{-1}$ at $10^{15}\,\mathrm{M}_{\odot}$ with slope $0.16 \pm 0.14$, consistent with most previous results.

Gas and dark matter in the Sculptor group: NGC 300

We used the Australia Telescope Compact Array to map a large field of approximately $2^{\circ} \times 2^{\circ}$ around the Sculptor group galaxy NGC~300 in the 21-cm line emission of neutral hydrogen. We achieved a $5 \sigma$ \ion{H}{i} column density sensitivity of $10^{19}~\mathrm{cm}^{-2}$ over a spectral channel width of $8~\mathrm{km \, s}^{-1}$ for emission filling the $180'' \times 88''$ synthesised beam. The corresponding \ion{H}{i} mass sensitivity is $1.2 \times 10^{5}~\mathrm{M}_{\odot}$, assuming a distance of $1.9~\mathrm{Mpc}$. For the first time, the vast \ion{H}{i} disc of NGC~300 has been mapped over its entire extent at a moderately high spatial resolution of about $1~\mathrm{kpc}$. NGC~300 is characterised by a dense inner \ion{H}{i} disc, well aligned with the optical disc of $290^{\circ}$ orientation angle, and an extended outer \ion{H}{i} disc with a major axis of more than $1^{\circ}$ on the sky (equivalent to a diameter of about $35~\mathrm{kpc}$) and a different orientation angle of $332^{\circ}$. A significant fraction (about 43~per cent) of the total detected \ion{H}{i} mass of $1.5 \times 10^{9}~\mathrm{M}_{\odot}$ resides within the extended outer disc. We fitted a tilted ring model to the velocity field of NGC~300 to derive the rotation curve out to a radius of $18.4~\mathrm{kpc}$, almost twice the range of previous rotation curve studies. The rotation curve rises to a maximum velocity of almost $100~\mathrm{km \, s}^{-1}$ and then gently decreases again in the outer disc beyond a radius of about $10~\mathrm{kpc}$. Mass models fitted to the derived rotation curve yield good fits for Burkert and NFW dark matter halo models, whereas pseudo-isothermal halo models and MOND-based models both struggle to cope with the declining rotation curve. We also observe significant asymmetries in the outer \ion{H}{i} disc of NGC~300, in particular near the edge of the disc, which are possibly due to ram pressure stripping of gas by the intergalactic medium (IGM) of the Sculptor group. Our estimates show that ram pressure stripping can occur under reasonable assumptions on the density of the IGM and the relative velocity of NGC~300. The asymmetries in the gas disc suggest a proper motion of NGC~300 toward the south-east. At the same time, our data exclude IGM densities of significantly higher than $10^{-5}~\mathrm{cm}^{-3}$ in the vicinity of NGC~300, as otherwise the outer gas disc would have been stripped.

A New Approach for Simulating Galaxy Cluster Properties

We describe a subgrid model for including galaxies into hydrodynamical cosmological simulations of galaxy cluster evolution. Each galaxy construct- or galcon- is modeled as a physically extended object within which star formation, galactic winds, and ram pressure stripping of gas are modeled analytically. Galcons are initialized at high redshift (z~3) after galaxy dark matter halos have formed but before the cluster has virialized. Each galcon moves self-consistently within the evolving cluster potential and injects mass, metals, and energy into intracluster (IC) gas through a well-resolved spherical interface layer. We have implemented galcons into the Enzo adaptive mesh refinement code and carried out a simulation of cluster formation in a LambdaCDM universe. With our approach, we are able to economically follow the impact of a large number of galaxies on IC gas. We compare the results of the galcon simulation with a second, more standard simulation where star formation and feedback are treated using a popular heuristic prescription. One advantage of the galcon approach is explicit control over the star formation history of cluster galaxies. Using a galactic SFR derived from the cosmic star formation density, we find the galcon simulation produces a lower stellar fraction, a larger gas core radius, a more isothermal temperature profile, and a flatter metallicity gradient than the standard simulation, in better agreement with observations.

Stellar Populations of Dwarf Elliptical Galaxies:UBVRIPhotometry of Dwarf Elliptical Galaxies in the Virgo Cluster

We present UBVRI surface photometry for 16 dwarf elliptical galaxies in the Virgo Cluster with previously measured kinematic properties. The global optical colors are red, with median values for the sample of 0.24 ? 0.03 in U - B, 0.77 ? 0.02 in B - V, and 1.02 ? 0.03 in V - I. We recover the well-known color-magnitude relation for cluster galaxies but find no significant difference in dominant stellar population between rotating and nonrotating dwarf elliptical galaxies; the average age of the dominant stellar population is 5?7 Gyr in all 16 galaxies in this sample. Analysis of optical spectra confirm these age estimates and indicate Fe and Mg abundances in the range of 1/20 to one-third of solar, as expected for low-luminosity galaxies. Based on Lick indices and simple stellar population models, the derived [?/Fe] ratios are subsolar to solar, indicating a more gradual chemical enrichment history for dE's as compared with giant elliptical galaxies in the Virgo Cluster. These observations confirm the marked difference in stellar population and stellar distribution between dwarf and giant elliptical galaxies and further substantiate the need for alternative evolutionary scenarios for the lowest mass cluster galaxies. We argue that it is likely that several different physical mechanisms played a significant role in the production of the Virgo Cluster dE galaxies including in situ formation, infall of dE's that were once part of Local Group analogs, and transformation of dwarf irregular galaxies by the cluster environment. The observations support the hypothesis that a large fraction of the Virgo Cluster dE's are formed by ram pressure stripping of gas from infalling dI's.

Metallicity Gradients in the Intracluster Gas of Abell 496

Analysis of spatially resolved ASCA spectra of the intracluster gas in Abell 496 confirms there are mild metal abundance enhancements near the center, as previously found in a joint analysis of spectra from Ginga Large Area Counter and Einstein solid state spectrometer. Simultaneous analysis of spectra from all ASCA instruments (SIS + GIS) shows that the iron abundance is 0.36 ± 0.03 solar 3'-12' from the center of the cluster and rises ~50% to 0.53 ± 0.04 solar within the central 2'. The F-test shows that this abundance gradient is significant at the more than 99.99% level. Nickel and sulfur abundances are also centrally enhanced. We use a variety of elemental abundance ratios to assess the relative contribution of Type Ia supernovae (SNe Ia) and Type II supernovae (SNe II) to the metal enrichment of the intracluster gas. We find spatial gradients in several abundance ratios, indicating that the fraction of iron from SNe Ia increases toward the cluster center, with SNe Ia accounting for ~50% of the iron mass 3'-12' from the center and ~70% within 2'. The increased proportion of SN Ia ejecta at the center is such that the central iron abundance enhancement can be attributed wholly to SNe Ia; we find no significant gradient in SN II ejecta. These spatial gradients in the proportion of SN Ia/II ejecta imply that the dominant metal enrichment mechanism near the center is different than in the outer parts of the cluster. We show that the central abundance enhancement is unlikely to be due to ram pressure stripping of gas from cluster galaxies or to secularly accumulated stellar mass loss within the central cD. We suggest that the additional SN Ia ejecta near the center is the vestige of a secondary SN Ia-driven wind from the cD (following a more energetic protogalactic SN II-driven wind phase), which was partially smothered in the cD due to its location at the cluster center.

Ram pressure stripping of spiral galaxies in clusters

We use three-dimensional SPH/N-body simulations to study ram pressure stripping of gas from spiral galaxies orbiting in clusters. We find that the analytic expectation of Gunn & Gott, relating the gravitational restoring force provided by the disc to the ram pressure force, provides a good approximation to the radius at which gas will be stripped from a galaxy. However, at small radii it is also important to consider the potential provided by the bulge component. A spiral galaxy passing through the core of a rich cluster, such as Coma, will have its gaseous disc truncated to ∼4 kpc, thus losing ∼80 per cent of its diffuse gas mass. The time-scale for this to occur is a fraction of a crossing time ∼107 yr. Galaxies orbiting within poorer clusters, or inclined to the direction of motion through the intracluster medium, will lose significantly less gas. We conclude that ram pressure alone is insufficient to account for the rapid and widespread truncation of star formation observed in cluster galaxies, or the morphological transformation of Sabs to S0s that is necessary to explain the Butcher-Oemler effect.

A Search for Tidal Stellar Debris from the Magellanic Clouds: Survey Results from the First Two Years

An important discriminant between leading models for the origin of the Magellanic Stream is the presence of a stellar counterpart to the HI gas stream: ram pressure stripping of gas by a putative hot Galactic halo would act only on Magellanic gas while gravitational tidal stripping would act on both gas and stars. Several previous attempts to find tidal stellar debris have failed to find carbon stars, A stars, or other main sequence stars in the Magellanic Stream (Mathewson et al. 1979; Recillas-Cruz 1982; Brück & Hawkins 1983; Guhathakurta & Lin 1999). However, there has long been a suggestion (Kunkel 1979; Lynden-Bell 1982) of a possible Magellanic association of satellite galaxies and globular clusters that have similar orbits and may derive from the break up of a greater Magellanic galaxy (Lynden-Bell & Lynden-Bell 1995; Majewski et al. 1997). Recent models (Moore & Davis 1994; Johnston 1998) of the tidal disruption of Large Magellanic Cloud (LMC)-like systems indicate a wide dispersal of debris, much wider than the rather confined HI stream, so that the contrast of tidal debris against the Galactic fore/background would be low. If true, this could explain some of the previous negative results for tidal debris searches.

Ram-pressure stripping of gas from companions and accretion onto a spiral galaxy: A gaseous merger

view Abstract Citations (26) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ram-Pressure Stripping of Gas from Companions and Accretion onto a Spiral Galaxy: A Gaseous Merger Sofue, Yoshiaki Abstract We simulated the behavior of interstellar gas clouds in a companion galaxy during a gasdynamical interaction with the halo and disk of a spiral galaxy. Due to the ram pressure, the gas clouds are stripped from the companion and accreted toward the disk of the spiral galaxy. If the companion's orbit is retrograde with respect to the rotation of the spiral galaxy, infalling clouds hit the nuclear region. Angular momentum transfer causes disruption of the inner gaseous disk and makes a void of interstellar gas in the bulge. If the companion's orbit is either prograde or polar, infalling clouds are accreted by the outer disk and form a rotating gas ring. We show that the ram-pressure stripping and accretion is one way from the companion to a gas-rich larger galaxy, which causes disposal of interstellar gas from the companion and effectively changes its galaxy type into an earlier (redder) type. The ram-pressure process is significant during the merger of galaxies, in which interstellar gas is stripped and accreted prior to the stellar body merger. Based on the simulation, we discuss a possible history of interstellar gas in the M31 system, which comprises M32, NGC 205, and possible merged galaxies. The ram-pressure stripping explains the disposal of mass lost from evolving stars in the dwarf elliptical companion M32. The peculiar "face-on" spirals of ionized gas and dark clouds observed in M 31's bulge can be reproduced by a spiral inflow of accreting gas from the companions and/or from the merger galaxy. Publication: The Astrophysical Journal Pub Date: March 1994 DOI: 10.1086/173800 arXiv: arXiv:astro-ph/9309045 Bibcode: 1994ApJ...423..207S Keywords: Astronomical Models; Gaseous Diffusion; Interstellar Gas; Pressure Effects; Spiral Galaxies; Angular Momentum; Galactic Halos; Gas Ionization; Mass Transfer; Astrophysics; ACCRETION; ACCRETION DISKS; GALAXIES: INDIVIDUAL MESSIER NUMBER: M31; GALAXIES: INDIVIDUAL MESSIER NUMBER: M32; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 205; GALAXIES: INTERACTIONS; GALAXIES: ISM; Astrophysics E-Print: (to appear in Ap.J.), plainTeX, 12p, U-Tokyo Astro. No. 93-26 full text sources arXiv | ADS | data products SIMBAD (3) NED (3)