Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAn enormous molecular gas flow in the RXJ0821+0752 galaxy cluster
58
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present recent {it Chandra} X-ray observations of the RXJ0821.0+0752 galaxy cluster in addition to ALMA observations of the CO(1-0) and CO(3-2) line emission tracing the molecular gas in its central galaxy. All of the CO line emission, originating from a $10^{10},M_{odot}$ molecular gas reservoir, is located several kpc away from the nucleus of the central galaxy. The cold gas is concentrated into two main clumps surrounded by a diffuse envelope. They form a wide filament coincident with a plume of bright X-ray emission emanating from the cluster core. This plume encompasses a putative X-ray cavity that is only large enough to have uplifted a few percent of the molecular gas. Unlike other brightest cluster galaxies, stimulated cooling, where X-ray cavities lift low entropy cluster gas until it becomes thermally unstable, cannot have produced the observed gas reservoir. Instead, the molecular gas has likely formed as a result of sloshing motions in the intracluster medium induced by a nearby galaxy. Sloshing can emulate uplift by dislodging gas from the galactic center. This gas has the shortest cooling time, so will condense if disrupted for long enough.
rate research
Read More
We report ALMA Early Science observations of the Abell 1835 brightest cluster galaxy (BCG) in the CO (3-2) and CO (1-0) emission lines. We detect $5times 10^{10}~rm M_odot$ of molecular gas within 10 kpc of the BCG. Its ensemble velocity profile width of $sim 130 ~rm km~s^{-1}$ FWHM is too narrow for the molecular cloud sto be supported in the galaxy by dynamic pressure. The gas may instead be supported in a rotating, turbulent disk oriented nearly face-on. Roughly $10^{10}~rm M_odot$ of molecular gas is projected $3-10 ~rm kpc$ to the north-west and to the east of the nucleus with line of sight velocities lying between $-250 ~rm km~s^{-1}$ to $+480 ~rm km~s^{-1}$ with respect to the systemic velocity. The high velocity gas may be either inflowing or outflowing. However, the absence of high velocity gas toward the nucleus that would be expected in a steady inflow, and its bipolar distribution on either side of the nucleus, are more naturally explained as outflow. Star formation and radiation from the AGN are both incapable of driving an outflow of this magnitude. If so, the molecular outflow may be associated a hot outflow on larger scales reported by Kirkpatrick and colleagues. The molecular gas flow rate of approximately $200~rm M_odot ~yr^{-1}$ is comparable to the star formation rate of $100-180~rm M_odot ~yr^{-1}$ in the central disk. How radio bubbles would lift dense molecular gas in their updrafts, how much gas will be lost to the BCG, and how much will return to fuel future star formation and AGN activity are poorly understood. Our results imply that radio-mechanical (radio mode) feedback not only heats hot atmospheres surrounding elliptical galaxies and BCGs, it is able to sweep higher density molecular gas away from their centers.
We present new ALMA observations of the molecular gas and far-infrared continuum around the brightest cluster galaxy (BCG) in the cool-core cluster MACS 1931.8-2635. Our observations reveal $1.9 pm 0.3 times 10^{10}$ M$_{odot}$ of molecular gas, on par with the largest known reservoirs of cold gas in a cluster core. We detect CO(1-0), CO(3-2), and CO(4-3) emission from both diffuse and compact molecular gas components that extend from the BCG center out to $sim30$ kpc to the northwest, tracing the UV knots and H$alpha$ filaments observed by HST. Due to the lack of morphological symmetry, we hypothesize that the $sim300$ km s$^{-1}$ velocity of the CO in the tail is not due to concurrent uplift by AGN jets, rather we may be observing the aftermath of a recent AGN outburst. The CO spectral line energy distribution suggests that molecular gas excitation is influenced by processes related to both star formation and recent AGN feedback. Continuum emission in Bands 6 and 7 arises from dust and is spatially coincident with young stars and nebular emission observed in the UV and optical. We constrain the temperature of several dust clumps to be $lesssim 10$ K, which is too cold to be directly interacting with the surrounding $sim 4.8$ keV intracluster medium (ICM). The cold dust population extends beyond the observed CO emission and must either be protected from interacting with the ICM or be surrounded by local volumes of ICM that are several keV colder than observed by Chandra.
We present the serendipitous discovery of an extended cold gas structure projected close to the brightest cluster galaxy (BCG) of the z=0.045 cluster Abell 3716, from archival integral field spectroscopy. The gas is revealed through narrow Na D line absorption, seen against the stellar light of the BCG, which can be traced for $sim$25 kpc, with a width of 2-4 kpc. The gas is offset to higher velocity than the BCG (by $sim$100 km/s), showing that it is infalling rather than outflowing; the intrinsic linewidth is $sim$80 km/s (FWHM). Very weak H$alpha$ line emission is detected from the structure, and a weak dust absorption feature is suggested from optical imaging, but no stellar counterpart has been identified. We discuss some possible interpretations for the absorber: as a projected low-surface-brightness galaxy, as a stream of gas that was stripped from an infalling cluster galaxy, or as a retired cool-core nebula filament.
Enormous Ly$alpha$ nebulae, extending over 300-500,kpc around quasars, represent the pinnacle of galaxy and cluster formation. Here we present IRAM Plateau de Bure Interferometer observations of the enormous Ly$alpha$ nebulae `Slug ($z$=$2.282$) and `Jackpot ($z$=$2.041$). Our data reveal bright, synchrotron emission associated with the two radio-loud AGN embedded in the targeted nebulae, as well as molecular gas, as traced via the CO(3-2) line, in three galaxies (two sources in the Slug, and one in the Jackpot). All of the CO emission is associated with galaxies detected in their rest-frame UV stellar emission. The total mass in molecular gas of these three galaxies [$sim (3-5)times10^{10}$ M$_odot$] is comparable with the total ionized gas mass responsible for the diffuse nebular emission. Our observations place limits on the molecular gas emission in the nebulae: The molecular gas surface density is $Sigma_{rm H2}<12-25$ M$_odot$ pc$^{-2}$ for the Slug nebula and $Sigma_{rm H2}<34-68$ M$_odot$ pc$^{-2}$ for the Jackpot nebula. These are consistent with the expected molecular gas surface densities, as predicted via photoionization models of the rest-frame UV line emission in the nebulae, and via Ly$alpha$ absorption in the Jackpot nebula. Compared to other radio--loud quasars at $z>1$, and high-redshift radio--loud galaxies, we do not find any strong trends relating the molecular gas reservoirs, the radio power, and the Ly$alpha$ luminosities of these systems. The significant step in sensitivity required to achieve a detection of the molecular gas from the nebulae, if present, will require a substantial time investment with JVLA, NOEMA, or ALMA.
We present here the first of a series of papers aimed at better understanding the evolution and properties of giant molecular clouds (GMCs) in a galactic context. We perform high resolution, three-dimensional {sc arepo} simulations of an interacting galaxy inspired by the well-observed M51 galaxy. Our fiducial simulations include a non-equilibrium, time-dependent, chemical network that follows the evolution of atomic and molecular hydrogen as well as carbon and oxygen self-consistently. Our calculations also treat gas self-gravity and subsequent star formation (described by sink particles), and coupled supernova feedback. In the densest parts of the simulated interstellar medium (ISM) we reach sub-parsec resolution, granting us the ability to resolve individual GMCs and their formation and destruction self-consistently throughout the galaxy. In this initial work we focus on the general properties of the ISM with a particular focus on the cold star-forming gas. We discuss the role of the interaction with the companion galaxy in generating cold molecular gas and controlling stellar birth. We find that while the interaction drives large-scale gas flows and induces spiral arms in the galaxy, it is of secondary importance in determining gas fractions in the different ISM phases and the overall star-formation rate. The behaviour of the gas on small GMC scales instead is mostly controlled by the self-regulating property of the ISM driven by coupled feedback.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
