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The H <small>i</small> environment of counter‐rotating gas hosts: gas accretion from cold gas blobs
Chung, Aeree,Bureau, Martin,van Gorkom, J. H.,Koribalski, Bä,rbel Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.422 No.2
<P><B>ABSTRACT</B></P><P>We probe the H <SMALL>i</SMALL> properties and the gas environments of three early‐type barred galaxies harbouring counter‐rotating ionized gas: NGC 128, NGC 3203 and NGC 7332. Each system has one or more optically identified galaxy at a similar or as yet unknown redshift within a 50‐kpc projected radius. Using H <SMALL>i</SMALL> synthesis imaging data, we investigate the hypothesis that the counter‐rotating gas in these galaxies has been accreted from their neighbours. In NGC 128 and NGC 3203, we find 9.6 × 10<SUP>7</SUP> and 2.3 × 10<SUP>8</SUP> M<SUB>⊙</SUB> of H <SMALL>i</SMALL>, respectively, covering almost the entire stellar bodies of dwarf companions that appear physically connected. Both the H <SMALL>i</SMALL> morphology and kinematics are suggestive of tidal interactions. In NGC 7332, we do not find any directly associated H <SMALL>i</SMALL>. Instead, NGC 7339, a neighbour of a comparable size at about 10 kpc, is found with 8.9 × 10<SUP>8</SUP> M<SUB>⊙</SUB> of H <SMALL>i</SMALL> gas. More recently in a single dish observation, however, another group discovered a large H <SMALL>i</SMALL> structure which seems to be an extension of NGC 7339’s H <SMALL>i</SMALL> disc and also covers NGC 7332. All these observations thus suggest that H <SMALL>i</SMALL> gas is being accreted in these three galaxies from their companions, which is likely responsible for the kinematically decoupled gas component present in their central region. In particular, the dynamical friction time‐scales of the nearest neighbours with H <SMALL>i</SMALL> gas of NGC 128 and NGC 3203 are comparable to their orbital time‐scales around the counter‐rotators, several ∼10<SUP>8</SUP> yr, implying that those neighbours will likely soon merge with the primary galaxies, fuelling them with gas. NGC 7332 also appears to be in the merging process with its neighbour through the common H <SMALL>i</SMALL> envelope. Besides, we find some other potential gas donors around NGC 128 and NGC 7332: two H <SMALL>i</SMALL>‐rich galaxies with <IMG src='/wiley-blackwell_img/equation/MNR_20679_mu1.gif' alt ='inline image'/> and 2.5 × 10<SUP>9</SUP> M<SUB>⊙</SUB> at a distance of ≈67 kpc from NGC 128 and two dwarf systems with <I>M</I><SUB>HI</SUB>= 3.9 × 10<SUP>7</SUP> and 7.4 × 10<SUP>7</SUP> M<SUB>⊙</SUB> at ≲100 kpc from NGC 7332. Among the seven H <SMALL>i</SMALL> features identified in this study, three of them are associated with dwarf galaxies, two of which have only been recently identified in a blind survey, while the third one is still not catalogued at optical wavelengths. Considering the incompleteness of existing studies of the faint dwarf galaxy population both in the optical and in H <SMALL>i</SMALL>, accretion from cold gas blobs, presumably gas‐rich dwarfs, is expected to occur even more frequently than what is inferred from such cases that have been observed to date.</P>
Ferná,ndez, Ximena,Gim, Hansung B.,Gorkom, J. H. van,Yun, Min S.,Momjian, Emmanuel,Popping, Attila,Chomiuk, Laura,Hess, Kelley M.,Hunt, Lucas,Kreckel, Kathryn,Lucero, Danielle,Maddox, Natasha,Oo American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.824 No.1
<P>Our current understanding of galaxy evolution still has many uncertainties associated with the details of the accretion, processing, and removal of gas across cosmic time. The next generation of radio telescopes will image the neutral hydrogen (H I) in galaxies over large volumes at high redshifts, which will provide key insights into these processes. We are conducting the COSMOS H I Large Extragalactic Survey (CHILES) with the Karl G. Jansky Very Large Array, which is the first survey to simultaneously observe H I from z = 0 to z similar to 0.5. Here, we report the highest redshift H I 21 cm detection in emission to date of the luminous infrared galaxy COSMOS J100054.83+023126.2 at z = 0.376 with the first 178 hr of CHILES data. The total H I mass is (2.9 +/- 1.0) x 10(10) M-circle dot and the spatial distribution is asymmetric and extends beyond the galaxy. While optically the galaxy looks undisturbed, the H I distribution suggests an interaction with a candidate companion. In addition, we present follow-up Large Millimeter Telescope CO observations that show it is rich in molecular hydrogen, with a range of possible masses of (1.8-9.9) x 10(10) M-circle dot. This is the first study of the H I and CO in emission for a single galaxy beyond z similar to 0.2.</P>
CAUGHT IN THE ACT: STRONG, ACTIVE RAM PRESSURE STRIPPING IN VIRGO CLUSTER SPIRAL NGC 4330
Abramson, Anne,Kenney, Jeffrey D. P.,Crowl, Hugh H.,Chung, Aeree,van Gorkom, J. H.,Vollmer, Bernd,Schiminovich, David American Institute of Physics 2011 The Astronomical journal Vol.141 No.5
<P>We present a multi-wavelength study of NGC 4330, a highly inclined spiral galaxy in the Virgo Cluster which is a clear example of strong, ongoing intracluster medium-interstellar medium (ICM-ISM) ram pressure stripping. The H <SPAN CLASS='sml'>I</SPAN> has been removed from well within the undisturbed old stellar disk, to 50%-65% of R<SUB>25</SUB>. Multi-wavelength data (WIYN BVR-Hα, Very Large Array 21 cm H <SPAN CLASS='sml'>I</SPAN> and radio continuum, and Galaxy Evolution Explorer NUV and FUV) reveal several one-sided extraplanar features likely caused by ram pressure at an intermediate disk-wind angle. At the leading edge of the interaction, the Hα and dust extinction curve sharply out of the disk in a remarkable and distinctive 'upturn' feature that may be generally useful as a diagnostic indicator of active ram pressure. On the trailing side, the ISM is stretched out in a long tail which contains 10% of the galaxy's total H <SPAN CLASS='sml'>I</SPAN> emission, 6%-9% of its NUV-FUV emission, but only 2% of the Hα. The centroid of the H <SPAN CLASS='sml'>I</SPAN> tail is downwind of the UV/Hα tail, suggesting that the ICM wind has shifted most of the ISM downwind over the course of the past 10-300 Myr. Along the major axis, the disk is highly asymmetric in the UV, but more symmetric in Hα and H <SPAN CLASS='sml'>I</SPAN>, also implying recent changes in the distributions of gas and star formation. The UV-optical colors indicate very different star formation histories for the leading and trailing sides of the galaxy. On the leading side, a strong gradient in the UV-optical colors of the gas-stripped disk suggests that it has taken 200-400 Myr to strip the gas from a radius of >8 to 5 kpc, but on the trailing side there is no age gradient. All our data suggest a scenario in which NGC 4330 is falling into the cluster center for the first time and has experienced a significant increase in ram pressure over the last 200-400 Myr. Many of the UV-bright stars that form outside the thin disk due to ram pressure will ultimately produce stellar thick disk and halo components with characteristic morphologies and age distributions distinct from those produced by gravitational interactions.</P>
PRE-PROCESSING OF GALAXIES IN THE FILAMENTS AROUND THE VIRGO CLUSTER
YOON, HYEIN,CHUNG, AEREE,SENGUPTA, CHANDREYEE,WONG, O. IVY,BUREAU, MARTIN,REY, SOO-CHANG,VAN GORKOM, J.H. The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
Galaxies can be "pre-processed" in the low-density outskirts by ambient medium in the filaments or tidal interactions with other galaxies while falling into the cluster. In order to probe how early on and by which mechanisms galaxies can be affected before they enter high-density cluster environments, we are carrying out an atomic hydrogen ($H\small{I}$) imaging study of a sample of galaxies selected from three filamentary structures around the Virgo cluster. Our sample consists of 14 late-type galaxies, which are potentially interacting with their surroundings. The $H\small{I}$ observations have been done using the Westerbork Synthesis Radio Telescope, the Giant Metrewave Radio Telescope, and the Jansky Very Large Array with column density sensitivity of ${\approx}3-5{\times}10^{19}cm^{-2}$ in $3{\sigma}$ per channel, which is low enough to detect faint $H\small{I}$ features in the outer disks of galaxies. In this work, we present the Hi data of two galaxies that were observed with GMRT. We examine the $H\small{I}$ morphology and kinematics to find the evidence for gas-gas and/or tidal interactions, and discuss which mechanism(s) could be responsible for pre-processing in these cases.
CHILES: H i morphology and galaxy environment at <i>z</i> = 0.12 and <i>z</i> = 0.17
Hess, Kelley M,Luber, Nicholas M,Ferná,ndez, Ximena,Gim, Hansung B,van Gorkom, J H,Momjian, Emmanuel,Gross, Julia,Meyer, Martin,Popping, Attila,Davies, Luke J M,Hunt, Lucas,Kreckel, Kathryn,Luce Oxford University Press 2019 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.484 No.2