MeerKAT HI imaging of the jellyfish galaxy ESO 137-001

¹ Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University, Makhanda 6140, South Africa
² INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius, (CA), Italy
³ Department of Physics and Astronomy, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899, USA
⁴ South African Radio Astronomy Observatory, Black River Park North, 2 Fir St, Cape Town 7925, South Africa
⁵ Institute for Radioastronomy, National Institute of Astrophysics (INAF IRA), Via Gobetti 101, 40129 Bologna, Italy
⁶ School of Physics, University of the Witwatersrand, Johannesburg, Gauteng, South Africa

^⋆ Corresponding author; m.ramatsoku@ru.ac.za

Received: 10 June 2024
Accepted: 26 December 2024

Abstract

We present MeerKAT H I observations of ESO 137-001, a quintessential jellyfish galaxy with long multi-phase tails formed due to the interaction with the intra-cluster medium of its host galaxy cluster, ACO 3627. Our observations reveal the presence of H I in both the disc and outer regions of the galaxy for the first time, with a total H I mass of (3.5 ± 0.4)×10⁸ M_⊙. ESO 137-001 is at an advanced stage of gas stripping; it is extremely H I deficient and seems to have lost 90% of its initial H I mass; about 2/3 of the surviving H I is found at larger radius than expected for a normal H I disc and forms ∼40 kpc tail coincident with the tail detected at other wavelengths. Only ∼10% of the surviving H I is still found within the stellar disc, consistent with the expectation of an outside-in truncation due to ram pressure. Similarly to other jellyfish galaxies, ESO137-001 has a high star formation rate for the low amount of H I detected. We measure an H I depletion time of 0.29 Gyr. However, when taking into account the total gas (H I + H₂) content, the depletion time is consistent with typical values measured in nearby spiral galaxies. This suggests that ESO 137-001 is at its current stage of ram pressure interaction characterised by an efficient H I stripping, rather than an enhanced conversion of H I to H₂, which was recently observed in some other jellyfish galaxies.