Tidal origin of NGC 1427A in the Fornax cluster

Lee-Waddell, K.; Serra, P.; Koribalski, B. S.; Venhola, Aku; Iodice, E.; Catinella, Barbara; Cortese, Luca; Peletier, Reynier F.; Popping, Attila; Keenan, Olivia; Capaccioli, M.

doi:10.1093/mnras/stx2808

Cited by 23 publications

(42 citation statements)

References 41 publications

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“…Thus, it may be a new Fornax member which is infalling from the foreground. As already mentioned, Lee-Waddell et al (2018) studied the origin of the HI tail using the same data we present here. They concluded that, unlike previously suggestions, ram-pressure is unlikely to be the main process shaping the galaxy's optical appearance.…”

Section: Discussionmentioning

confidence: 85%

A blind ATCA HI survey of the Fornax galaxy cluster

Loni

Serra

Kleiner

et al. 2021

A&A

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We present the first interferometric blind HI survey of the Fornax galaxy cluster, which covers an area of 15 deg2 out to the cluster virial radius. The survey has a spatial and velocity resolution of 67″ × 95″(∼6 × 9 kpc at the Fornax cluster distance of 20 Mpc) and 6.6 km s−1 and a 3σ sensitivity of NHI ∼ 2 × 1019 cm−2 and MHI ∼ 2 × 107 M⊙, respectively. We detect 16 galaxies out of roughly 200 spectroscopically confirmed Fornax cluster members. The detections cover about three orders of magnitude in HI mass, from 8 × 106 to 1.5 × 1010 M⊙. They avoid the central, virialised region of the cluster both on the sky and in projected phase-space, showing that they are recent arrivals and that, in Fornax, HI is lost within a crossing time, ∼2 Gyr. Half of these galaxies exhibit a disturbed HI morphology, including several cases of asymmetries, tails, offsets between HI and optical centres, and a case of a truncated HI disc. This suggests that these recent arrivals have been interacting with other galaxies, the large-scale potential or the intergalactic medium, within or on their way to Fornax. As a whole, our Fornax HI detections are HI-poorer and form stars at a lower rate than non-cluster galaxies in the same M⋆ range. This is particularly evident at M⋆ ≲ 109 M⊙, indicating that low mass galaxies are more strongly affected throughout their infall towards the cluster. The MHI/M⋆ ratio of Fornax galaxies is comparable to that in the Virgo cluster. At fixed M⋆, our HI detections follow the non-cluster relation between MHI and the star formation rate, and we argue that this implies that thus far they have lost their HI on a timescale ≳1−2 Gyr. Deeper inside the cluster HI removal is likely to proceed faster, as confirmed by a population of HI-undetected but H2-detected star-forming galaxies. Overall, based on ALMA data, we find a large scatter in H2-to-HI mass ratio, with several galaxies showing an unusually high ratio that is probably caused by faster HI removal. Finally, we identify an HI-rich subgroup of possible interacting galaxies dominated by NGC 1365, where pre-processing is likely to have taken place.

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Section: Discussionmentioning

confidence: 85%

A blind ATCA HI survey of the Fornax galaxy cluster

Loni

Serra

Kleiner

et al. 2021

A&A

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“…The tail shows low SB regions, and the top part is elongated with the south, moving in opposite directions. NGC 1437A has about one third the Himass as NGC 1427A and the velocity difference between these dIrrs is 1150 km s −1 , which is three times higher than the velocity dispersion of the Fornax cluster (Lee-Waddell et al 2018) with no indication of recent tidal interactions.…”

Section: A8 Fcc285mentioning

confidence: 81%

“…Galaxies with asymmetric stellar discs (FCC113 and FCC285) could have experienced similar mechanisms during infall, but after the cluster collapse (Whitmore 1993). Since these galaxies have tidal disturbances similar to NGC 1427A, another possible mechanism for this is that it was triggered by a recent fly-by of another galaxy in the cluster (Lee-Waddell et al 2018). However, more analysis on the Hi distribution of these galaxies are required to confirm the possibility of ram-pressure stripping acting on them (e.g.…”

Section: Evolution Of Ltgs Inside the Virial Radius Of The Fornax Clumentioning

confidence: 99%

The Fornax Deep Survey with the VST

Raj

Iodice

Napolitano

et al. 2019

A&A

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Context. We present the study of a magnitude limited sample (mB ≤ 16.6 mag) of 13 late type galaxies (LTGs), observed inside the virial radius, Rvir ∼ 0.7 Mpc, of the Fornax cluster within the Fornax Deep Survey (FDS). Aims. The main objective is to use surface brightness profiles and g − i colour maps to obtain information on the internal structure of these galaxies and find signatures of the mechanisms that drive their evolution in high-density environments inside the virial radius of the cluster. Methods. By modelling galaxy isophotes, we extract the azimuthally averaged surface brightness profiles in four optical bands. We also derive g − i colour profiles, and relevant structural parameters like total magnitude and effective radius. For ten of the galaxies in this sample, we observe a clear discontinuity in their typical exponential surface brightness profiles, derive their “break radius”, and classify their disc-breaks into Type II (down-bending) or Type III (up-bending). Results. We find that Type II galaxies have bluer average (g − i) colour in their outer discs while Type III galaxies are redder. The break radius increases with stellar mass and molecular gas mass while it decreases with molecular gas-fractions. The inner and outer scale-lengths increase monotonically with absolute magnitude, as found in other works. For galaxies with CO(1-0) measurements, there is no detected cold gas beyond the break radius (within the uncertainties). In the context of morphological segregation of LTGs in clusters, we also find that, in Fornax, galaxies with morphological type 5 < T ≤ 9 (∼60% of the sample) are located beyond the high-density, ETG-dominated regions, however there is no correlation between T and the disc-break type. We do not find any correlation between the average (g − i) colours and cluster-centric distance, but the colour-magnitude relation holds true. Conclusions. The main results of this work suggest that the disc-breaks of LTGs inside the virial radius of the Fornax cluster seem to have arisen through a variety of mechanisms (e.g. ram-pressure stripping, tidal disruption), which is evident in their outer-disc colours and the absence of molecular gas beyond their break radius in some cases. This can result in a variety of stellar populations inside and outside the break radii.

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“…NGC1427A has been proposed to be undergoing ram pressure stripping (Chanamé et al 2000;Mora et al 2015), although recent HI observations by Lee-Waddell et al (2018) suggest that previous tidal interactions are responsible for the galaxy's irregular shape, and for star formation triggering in the disk. It was detected in all five Herschel bands (Fuller et al 2014).…”

Section: Ngc1427amentioning

confidence: 99%

The ALMA Fornax Cluster Survey I: stirring and stripping of the molecular gas in cluster galaxies

Zabel

Davis

Smith

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present the first results of the ALMA Fornax Cluster Survey (AlFoCS): a complete ALMA survey of all members of the Fornax galaxy cluster that were detected in HI or in the far infrared with Herschel. The sample consists of a wide variety of galaxy types, ranging from giant ellipticals to spiral galaxies and dwarfs, located in all (projected) areas of the cluster. It spans a mass range of 10 ∼8.5−11 M . The CO(1-0) line was targeted as a tracer for the cold molecular gas, along with the associated 3 mm continuum. CO was detected in 15 of the 30 galaxies observed. All 8 detected galaxies with stellar masses below 3 × 10 9 M have disturbed molecular gas reservoirs, only 7 galaxies are regular/undisturbed. This implies that Fornax is still a very active environment, having a significant impact on its members. Both detections and non-detections occur at all projected locations in the cluster. Based on visual inspection, and the detection of molecular gas tails in alignment with the direction of the cluster centre, in some cases ram pressure stripping is a possible candidate for disturbing the molecular gas morphologies and kinematics. Derived gas fractions in almost all galaxies are lower than expected for field objects with the same mass, especially for the galaxies with disturbed molecular gas, with differences of sometimes more than an order of magnitude. The detection of these disturbed molecular gas reservoirs reveals the importance of the cluster environment for even the tightly bound molecular gas phase.

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Tidal origin of NGC 1427A in the Fornax cluster

Cited by 23 publications

References 41 publications

A blind ATCA HI survey of the Fornax galaxy cluster

A blind ATCA HI survey of the Fornax galaxy cluster

The Fornax Deep Survey with the VST

The ALMA Fornax Cluster Survey I: stirring and stripping of the molecular gas in cluster galaxies

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