scholarly journals GASP XXV: neutral hydrogen gas in the striking jellyfish galaxy JO204

2020 ◽  
Vol 494 (4) ◽  
pp. 5029-5043 ◽  
Author(s):  
Tirna Deb ◽  
Marc A W Verheijen ◽  
Marco Gullieuszik ◽  
Bianca M Poggianti ◽  
Jacqueline H van Gorkom ◽  
...  
Keyword(s):  
Neutral Hydrogen ◽  
Turbulent Medium ◽  
Hydrogen Gas ◽  
Radio Continuum ◽  
Absorption Profile ◽  
Ionized Gas ◽  
Absorption Column ◽  
Continuum Source ◽  
Neutral Gas ◽  
Ram Pressure

ABSTRACT We present JVLA-C observations of the H i gas in JO204, one of the most striking jellyfish galaxies from the GASP survey. JO204 is a massive galaxy in the low-mass cluster A957 at z = 0.04243. The H i map reveals an extended 90 kpc long ram-pressure stripped tail of neutral gas, stretching beyond the 30 kpc long ionized gas tail and pointing away from the cluster centre. The H i mass seen in emission is $(1.32\pm 0.13) \times 10^{9} \, \rm M_{\odot }$, mostly located in the tail. The northern part of the galaxy disc has retained some H i gas, while the southern part has already been completely stripped and displaced into an extended unilateral tail. Comparing the distribution and kinematics of the neutral and ionized gas in the tail indicates a highly turbulent medium. Moreover, we observe associated H i absorption against the 11 mJy central radio continuum source with an estimated H i absorption column density of 3.2 × 1020 cm−2. The absorption profile is significantly asymmetric with a wing towards higher velocities. We modelled the H i absorption by assuming that the H i and ionized gas discs have the same kinematics in front of the central continuum source, and deduced a wider absorption profile than observed. The observed asymmetric absorption profile can therefore be explained by a clumpy, rotating H i gas disc seen partially in front of the central continuum source, or by ram pressure pushing the neutral gas towards the centre of the continuum source, triggering the AGN activity.

scholarly journals Material in the Vicinity of Galaxies

1978 ◽  
Vol 77 ◽  
pp. 287-292
Author(s):  
Bernard F. Burke
Keyword(s):  
Cooling Rate ◽  
Neutral Hydrogen ◽  
Radio Galaxies ◽  
Hydrogen Gas ◽  
Clusters Of Galaxies ◽  
Ionized Gas ◽  
X Ray ◽  
Continuum Source ◽  
Irregular Galaxies ◽  
Background Continuum

It is increasingly certain that the principal concentrations of neutral hydrogen gas are in spiral and irregular galaxies. The intergalactic medium (IGM) appears to be either a near-void with <ρ> ≲ 1.5 × 10−11 cm−3 from the 3C9 measurements of Gunn and Peterson (1965) or at best a hot, highly ionized gas with very little neutral hydrogen present (Field and Perrenod, 1977). In clusters of galaxies, the intracluster medium (ICM) also appears to be mostly hot and ionized, as suggested by X-ray observations (Jones et al. 1977) and by observations of head-tail radio galaxies. Even if most of the IGM and ICM were ionized, however, one might imagine that there exist high-density concentrations where the cooling rate is sufficient to allow recombination, particularly in the vicinity of galaxies. One might expect such condensations to be revealed either by 21-cm emission, or by absorption against a bright background continuum source.

scholarly journals Neutral hydrogen gas within and around NGC 1316

2019 ◽  
Vol 628 ◽  
pp. A122 ◽  
Author(s):  
P. Serra ◽  
F. M. Maccagni ◽  
D. Kleiner ◽  
W. J. G. de Blok ◽  
J. H. van Gorkom ◽  
...  
Keyword(s):  
Large Scale ◽  
Molecular Form ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Neutral Gas ◽  
Tidal Forces ◽  
The Galaxy ◽  
Long Tails ◽  
Stellar Body ◽  
Fornax Cluster

We present MeerKAT observations of neutral hydrogen gas (H I) in the nearby merger remnant NGC 1316 (Fornax A), the brightest member of a galaxy group which is falling into the Fornax cluster. We find H I on a variety of scales, from the galaxy centre to its large-scale environment. For the first time we detect H I at large radii (70–150 kpc in projection), mostly distributed on two long tails associated with the galaxy. Gas in the tails dominates the H I mass of NGC 1316: 7 × 108 M⊙– 14 times more than in previous observations. The total H I mass is comparable to the amount of neutral gas found inside the stellar body, mostly in molecular form. The H I tails are associated with faint optical tidal features thought to be the remnant of a galaxy merger occurred a few billion years ago. They demonstrate that the merger was gas-rich. During the merger, tidal forces pulled some gas and stars out to large radii, where we now detect them in the form of optical tails and, thanks to our new data, H I tails; while torques caused the remaining gas to flow towards the centre of the remnant, where it was converted into molecular gas and fuelled the starburst revealed by the galaxy’s stellar populations. Several of the observed properties of NGC 1316 can be reproduced by a ∼10:1 merger between a dominant, gas-poor early-type galaxy and a smaller, gas-rich spiral occurred 1–3 Gyr ago, likely followed by subsequent accretion of satellite galaxies.

scholarly journals On the Propagation and Structure of Ionization Fronts

1958 ◽  
Vol 8 ◽  
pp. 1062-1068
Author(s):  
F. A. Goldsworthy
Keyword(s):  
Shock Wave ◽  
Ionizing Radiation ◽  
Atomic Hydrogen ◽  
Hydrogen Gas ◽  
Ionization Front ◽  
Ionized Gas ◽  
Hii Region ◽  
Ionization Fronts ◽  
Neutral Gas ◽  
Gravitational Equilibrium

The problem discussed here is that of determining the motion of a cloud of neutral atomic hydrogen gas, when it is subjected to ionizing radiation from a star embedded in it. Initially the gas is in gravitational equilibrium at a constant temperature of about 100°K. It is supposed that at time t=0 the star suddenly begins to radiate with a certain intensity, which remains constant thereafter. Part of the surrounding gas will be ionized and an ionization front (separating the ionized gas from the neutral gas) will move outwards into the neutral gas. A shock wave may also propagate ahead of the ionization front into the neutral gas. There will therefore be two regions to consider—a region of ionized gas (HII region) and a region of neutral gas (HI region) in which there may be a shock.

scholarly journals Radio Continuum of the Small Magellanie Cloud at Wavelengths 6 and 3·4 cm

1976 ◽  
Vol 29 (4) ◽  
pp. 329 ◽  
Author(s):  
RX McGee ◽  
Lynette M Newton ◽  
PW Butler
Keyword(s):  
Neutral Hydrogen ◽  
Magellanic Cloud ◽  
Radio Continuum ◽  
Radio Sources ◽  
Spectral Indices ◽  
Small Magellanic Cloud ◽  
Ionized Gas

The radio continuum at wavelength 6 cm has been surveyed in the direction of the Small Magellanic Cloud with a telescope beam of 4'�1 arc. Only 27 radio sources have been delineated in this galaxy, and details of their positions, flux densities and spectral indices are given. Some supporting observations were made of the stronger sources at 3�4 cm wavelength. The distribution of the 6 cm emission is compared with the distributions of the ionized gas and neutral hydrogen.

scholarly journals 21cm Absorption Lines at High Redshift from Intervening Galaxies

2002 ◽  
Vol 199 ◽  
pp. 83-90 ◽  
Author(s):  
F. H. Briggs
Keyword(s):  
Absorption Line ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Radio Galaxies ◽  
Hydrogen Gas ◽  
Absorption Lines ◽  
Radio Sources ◽  
Evolution Of Galaxies ◽  
Neutral Gas ◽  
Extended Radio

Radio absorption line observations of neutral hydrogen gas against extended radio sources offers the means to measure sizes and kinematics in intervening galaxies at all redshifts up to the maximum redshift where radio galaxies are detected. Such observations can therefore trace the evolution of galaxies at redshifts z ≳ 2 where the damped Lyman — α statistics indicate that the mass in neutral gas exceeded the mass in stars.

scholarly journals The Nearby Young Dwarf Galaxy SBS 0335-052: Primordial Gas and Lyman-Alpha Emission

1998 ◽  
Vol 11 (1) ◽  
pp. 115-116
Author(s):  
Trinh Xuan Thuan ◽  
Yuri I. Izotov
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Dwarf Galaxy ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Gas Content ◽  
Ionized Gas ◽  
Filamentary Structure ◽  
A Chain ◽  
Super Star Clusters

Ever since their discovery, blue compact dwarf (BCD) galaxies have been thought of as excellent candidates for being young galaxies, i.e. systems presently undergoing one of their very first bursts of star formation. This is mainly because BCDs are very metal-deficient, the metallicities of their ionized gas ranging between Zʘ/50 and Zʘ/3, which makes them the least chemically evolved galaxies in the Universe. Other evidence, such as the very high fractional neutral hydrogen gas content and the lack of an evident underlying old stellar population on optical images, also point to the relative youth of some BCDs. Thuan, Izotov h Lipovetsky (1997) have argued SBS 0335-052 to be a young galaxy on the basis of the following evidence: 1) HST imaging of the BCD shows its underlying extended low surface brightness component to have an irregular and filamentary structure, suggesting that a significant part of the emission (~1/3) comes not from an underlying stellar population, but from ionized gas. Any underlying stellar population must be younger than ~108yr. Propagating star formation occurs in a chain of 6 super-star clusters with ages ranging between 4 and 30 Myr. 2) The underlying component shows unusually blue colors consistent with gaseous emission, in contrast to most BCDs which possess an underlying red component. 3) VLA 21 cm observations show the BCD to be embedded in an extraordinarily large HI cloud with dimensions some 64 × 24 kpc (the typical size of HI envelopes around BCDs is more like a few kpc in each dimension).

scholarly journals Intermediate Resolution Spectroscopy of the Radio Galaxy B2 0902+34 at Z ≈ 3.4

1996 ◽  
Vol 168 ◽  
pp. 499-500
Author(s):  
J. L. Sanz ◽  
J. M. Martín-Mirones ◽  
E. Martínez-González ◽  
J. I. González-Serrano
Keyword(s):  
Galaxy Evolution ◽  
Spectral Range ◽  
Spectral Resolution ◽  
Radio Galaxy ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Radio Continuum ◽  
Continuum Source ◽  
The Galaxy ◽  
William Herschel

We have carried out optical spectroscopic observations at intermediate spectral resolution of the massive high redshift radio galaxy 0902+34 atz≈ 3.39. This source was first identified by Lilly (1988) (from hereafter L88). The study of high redshift radio galaxies is interesting to analyze the physical conditions of the early universe and the galaxy evolution at cosmological redshifts. It has been claimed that some of these systems may be protogalaxies in the process of formation. Indications for this are the flat spectrum and the absence of the 4000 Å break, features which have already been observed in many cases. In particular, observations in the spectral range fromVtoKsuggest that 0902+34 is a young galaxy (Eisenhardt and Dickinson 1992). Recent radio observations of the 21 cm line of neutral hydrogen have detected (Uson et al. 1991) an absorption against the radio continuum source. This absorption could also leave a track in the optical, redwards the Lyα line. Our observations were carried out with the ISIS spectrograph at the 4.2 m William Herschel Telescope (seeing ≈ 1.2–1.6 arcsec). A spectral dispersion of 0.78 Å/pixel (blue arm) and 1.38 Å/pixel (red arm) was obtained. Å long slit of width 3′ was used providing a spectral resolution of ≈ 5.4 Å in the blue arm and of ≈ 9.5 Å in the red one. Both resolutions are a clear improvement over that achieved by L88 of 20 Å, allowing us to resolve the Lyα line (and its possible structure) and any other possible strong features appearing in the spectral range observed (e. g., C iv λ1549, He ii λ1640, …). Six different observations of 2700 s of the radio galaxy 0902+34 were carried out. The slit was rotated to coincide with the parallactic angle at the beginning of each exposure. This will allow us to map spectroscopically different regions of the galaxy (for more details see Martín-Mirones et al. 1994).

scholarly journals Neutral Hydrogen Gas in Star Forming Galaxies at z=0.24

2007 ◽  
Vol 3 (S244) ◽  
pp. 366-367 ◽  
Author(s):  
Philip Lah ◽  
Jayaram N. Chengalur ◽  
Frank H. Briggs ◽  
Matthew Colless ◽  
Roberto De Propris ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Atomic Hydrogen ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Gas Content ◽  
Star Forming ◽  
Emission Signal ◽  
Neutral Gas

AbstractWe use observations from the Giant Metrewave Radio Telescope (GMRT) to measure the atomic hydrogen gas content of star-forming galaxies at z = 0.24 (i.e. a look-backtime of ~3 Gyr). To measure the HI 21 cm emission signal we stack the signal from 121 galaxies with known optical positions and redshifts. We find an average HI mass for the galaxies of (2.26 ± 0.90) × 109 M⊙. We translate this HI measurement into a cosmic density of neutral gas at z=0.24 of Ωgas = (0.91 ± 0.42) × 10−3. This value is consistent with that estimated from damped Lyα systems around this redshift.

scholarly journals 2-D Simulation for focus of rotating and propagating ion beam in neutral gas

1990 ◽  
Vol 8 (1-2) ◽  
pp. 89-93
Author(s):  
Takayuki Aoki ◽  
Keishiro Niu
Keyword(s):  
Field Emission ◽  
Plasma Density ◽  
Impact Ionization ◽  
Ion Beam ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Two Dimensional ◽  
Gas Density ◽  
Neutral Gas ◽  
Hybrid Code

Focusing processes of rotating and propagating proton beams in a neutral hydrogen gas are studied numerically by using a two-dimensional hybrid code. Processes including beam impact ionization, plasma avalanche and field emission are taken into consideration. The plasma formation time depends on the initial gas density and the beam intensity. When 2-Torr neutral gas is filled initially, enough plasma density is created by the rising part of the beam pulse, so that the main pulse is focused and forms a rotating and propagatingbeam configuration.

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° &lt;l&lt; 250°, + 40° &lt;b&lt; + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| &lt; 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

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