WALLABY Early Science – II. The NGC 7232 galaxy group

Lee-Waddell, K.; Koribalski, B. S.; Westmeier, T.; Elagali, Ahmed; For, Bi-Qing; Kleiner, D.; Madrid, Juan P.; Popping, Attila; Reynolds, T. N.; Rhee, J.; Serra, P.; Shao, Li; Staveley‐Smith, L.; Wang, Jing; Whiting, M. T.; Wong, O. I.; Allison, J. R.; Bhandari, Shivani; Collier, J. D.; Heald, G.; Marvil, J.; Ord, S. M.

doi:10.1093/mnras/stz017

Cited by 46 publications

(57 citation statements)

References 54 publications

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“…Many publications arose from the early science programme, as a result of identifying projects that the telescope could excel at with only a third of its collecting area. These include a continuum survey and detection of cold gas outflows from the small magellanic cloud (McClure-Griffiths et al 2018;Joseph et al 2019), studies of neutral hydrogen in nearby galaxy groups (Reynolds et al 2019;Lee-Waddell et al 2019;Elagali et al 2019;Kleiner et al 2019;For et al 2019), studies of absorption lines (Glowacki et al 2019;Allison et al 2020), continuum observations of the galaxy and mass assembly (GAMA) G23 field (Leahy et al 2019), searches for transient and variable sources (Bhandari et al 2018), and a few targeted studies of individual radio galaxies (e.g. Seymour et al 2020), including the polarisation characteristics of Centaurus A (Anderson et al 2018).…”

Section: Early Sciencementioning

confidence: 99%

Australian square kilometre array pathfinder: I. system description

Hotan

Bunton

Chippendale

et al. 2021

Publ. Astron. Soc. Aust.

235

159

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In this paper, we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first radio telescopes to deploy phased array feed (PAF) technology on a large scale, giving it an instantaneous field of view that covers $31\,\textrm{deg}^{2}$ at $800\,\textrm{MHz}$ . As a two-dimensional array of 36 $\times$ 12 m antennas, with baselines ranging from 22 m to 6 km, ASKAP also has excellent snapshot imaging capability and 10 arcsec resolution. This, combined with 288 MHz of instantaneous bandwidth and a unique third axis of rotation on each antenna, gives ASKAP the capability to create high dynamic range images of large sky areas very quickly. It is an excellent telescope for surveys between 700 and $1800\,\textrm{MHz}$ and is expected to facilitate great advances in our understanding of galaxy formation, cosmology, and radio transients while opening new parameter space for discovery of the unknown.

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Section: Early Sciencementioning

confidence: 99%

Australian square kilometre array pathfinder: I. system description

Hotan

Bunton

Chippendale

et al. 2021

Publ. Astron. Soc. Aust.

235

159

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“…Since the first interferometric observations of the Magellanic Clouds (Kerr, Hindman, & Robinson 1954;Hindman, Kerr, & McGee 1963), and of pairs and group galaxies in our nearest neighborhoods (Roberts 1968;Rots 1975), it was clear that environment can directly remove HI and create striking trails and streams. As showcased in Figure 14, we currently have a plethora of examples of HI stripping in groups, with most of the evidence pointing towards gravitational interactions as primarily responsible for creating these features (e.g., Yun, Ho, & Lo 1994;Hibbard et al 2001;Williams, Yun, & Verdes-Montenegro 2002;Koribalski, Gordon, & Jones 2003;Kantharia et al 2005;English et al 2010;Michel-Dansac et al 2010;Serra et al 2013Serra et al , 2015Leisman et al 2016;Hess et al 2017;de Blok et al 2018;Lee-Waddell et al 2019). This is due to the fact that, in most cases, stellar tidal features and/or peculiar optical morphologies are also clearly visible in these systems, suggesting a prominent role of tidal forces in affecting both their gas and stellar distributions.…”

Section: Hi Stripping In Groupsmentioning

confidence: 99%

The Dawes Review 9: The role of cold gas stripping on the star formation quenching of satellite galaxies

Cortese

Catinella

Smith

2021

Publ. Astron. Soc. Aust.

133

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One of the key open questions in extragalactic astronomy is what stops star formation in galaxies. While it is clear that the cold gas reservoir, which fuels the formation of new stars, must be affected first, how this happens and what are the dominant physical mechanisms involved is still a matter of debate. At least for satellite galaxies, it is generally accepted that internal processes alone cannot be responsible for fully quenching their star formation, but that environment should play an important, if not dominant, role. In nearby clusters, we see examples of cold gas being removed from the star-forming discs of galaxies moving through the intracluster medium, but whether active stripping is widespread and/or necessary to halt star formation in satellites, or quenching is just a consequence of the inability of these galaxies to replenish their cold gas reservoirs, remains unclear. In this work, we review the current status of environmental studies of cold gas in star-forming satellites in the local Universe from an observational perspective, focusing on the evidence for a physical link between cold gas stripping and quenching of the star formation. We find that stripping of cold gas is ubiquitous in satellite galaxies in both group and cluster environments. While hydrodynamical mechanisms such as ram pressure are important, the emerging picture across the full range of dark matter halos and stellar masses is a complex one, where different physical mechanisms may act simultaneously and cannot always be easily separated. Most importantly, we show that stripping does not always lead to full quenching, as only a fraction of the cold gas reservoir might be affected at the first pericentre passage. We argue that this is a key point to reconcile apparent tensions between statistical and detailed analyses of satellite galaxies, as well as disagreements between various estimates of quenching timescales. We conclude by highlighting several outstanding questions where we expect to see substantial progress in the coming decades, thanks to the advent of the Square Kilometre Array and its precursors, as well as the next-generation optical and millimeter facilities.

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“…This marks the first time WALLABY observations have reached the target WALLABY sensitivity (compared to ∼ 2.0-2.3 mJy beam −1 in Early Science, e.g. Reynolds et al 2019, Lee-Waddell et al 2019. We note that the sensitivity varies from ∼ 1.6-2.2 mJy across most of the field of view and increases to ∼ 3.7 mJy near the edges of the field.…”

Section: Datamentioning

confidence: 50%

“…In the lead up to full telescope operations and the full survey commencing, a number of smaller scale early science, pre-pilot and pilot survey data sets have been observed for verification and validation of the telescope and processing pipeline. WALLABY early science used a subset of 12-16 ASKAP antennas and limited bandwidth to observe four 30-square-degree fields (for details see Reynolds et al 2019;Lee-Waddell et al 2019;Elagali et al 2019;Kleiner et al 2019;For et al 2019). Pre-pilot observations of a single 30-square-degree field were the first WALLABY observations to use the full 36 antenna array of ASKAP and with its full bandwidth (for details see For et al in prep.…”

Section: The Australian Square Kilometre Array Pathfindermentioning

confidence: 99%

“…The WALLABY pilot survey observations of the Hydra I cluster were taken over four nights between 25-26 October and 20-24 November 2019. The raw ASKAP visibility data were flagged, calibrated and imaged using the ASKAP data processing software, ASKAP (Whiting 2020), using the standard method (see Reynolds et al 2019;Lee-Waddell et al 2019;Elagali et al 2019;Kleiner et al 2019;For et al 2019, for further details). The output spectral line cubes have a clean 30 arcsec synthesised beam (emission that was not cleaned because it is below the minor cycle deconvolution threshold of 3.5 mJy will have a slightly smaller beam size that varies with frequency, see Reynolds et al 2019 andKleiner et al 2019 for further details on cleaning).…”

Section: Datamentioning

confidence: 99%

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WALLABY pilot survey: first look at the Hydra I cluster and ram pressure stripping of ESO 501−G075

Reynolds

Westmeier

Elagali

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present results from neutral atomic hydrogen (H i) observations of Hydra I, the first cluster observed by the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) on the Australian Square Kilometre Array Pathfinder. For the first time we show that WALLABY can reach its final survey sensitivity. Leveraging the sensitivity, spatial resolution and wide field of view of WALLABY, we identify a galaxy, ESO 501−G075, that lies near the virial radius of Hydra I and displays an H i tail. ESO 501−G075 shows a similar level of morphological asymmetry as another cluster member, which lies near the cluster centre and shows signs of experiencing ram pressure. We investigate possible environmental processes that could be responsible for producing the observed disturbance in the H i morphology of ESO 501−G075. We rule out tidal interactions, as ESO 501−G075 has no nearby neighbours within ∼0.34 Mpc. We use a simple model to determine that ram pressure can remove gas from the disc at radii r ≳ 25 kpc. We conclude that, as ESO 501−G075 has a typical H i mass compared to similar galaxies in the field and its morphology is compatible with a ram pressure scenario, ESO 501−G075 is likely recently infalling into the cluster and in the early stages of experiencing ram pressure.

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WALLABY Early Science – II. The NGC 7232 galaxy group

Cited by 46 publications

References 54 publications

Australian square kilometre array pathfinder: I. system description

Australian square kilometre array pathfinder: I. system description

The Dawes Review 9: The role of cold gas stripping on the star formation quenching of satellite galaxies

WALLABY pilot survey: first look at the Hydra I cluster and ram pressure stripping of ESO 501−G075

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