We present the results from the HST WFC3 and ACS data on an archetypal galaxy undergoing ram pressure stripping (RPS), ESO 137-001, in the nearby cluster Abell 3627. ESO 137-001 is known to host a prominent stripped tail detected in many bands from X-rays, H α to CO. The HST data reveal significant features indicative of RPS such as asymmetric dust distribution and surface brightness as well as many blue young star complexes in the tail. We study the correlation between the blue young star complexes from HST, H ii regions from H α (MUSE), and dense molecular clouds from CO (ALMA). The correlation between the HST blue star clusters and the H ii regions is very good, while their correlation with the dense CO clumps are typically not good, presumably due in part to evolutionary effects. In comparison to the starburst99 + cloudy model, many blue regions are found to be young (<10 Myr) and the total star formation (SF) rate in the tail is 0.3–0.6 M⊙ yr−1 for sources measured with ages less than 100 Myr, about 40 per cent of the SF rate in the galaxy. We trace SF over at least 100 Myr and give a full picture of the recent SF history in the tail. We also demonstrate the importance of including nebular emissions and a nebular to stellar extinction correction factor when comparing the model to the broad-band data. Our work on ESO 137-001 demonstrates the importance of HST data for constraining the SF history in stripped tails.
Ram pressure stripping (RPS) is an important mechanism for galaxy evolution. In this work, we present results from HST and APEX observations of one RPS galaxy, ESO 137-002 in the closest rich cluster Abell 3627. The galaxy is known to host prominent X-ray and H α tails. The HST data reveal significant features indicative of RPS in the galaxy, including asymmetric distribution of dust in the galaxy, dust filaments, and dust clouds in ablation generally aligned with the direction of ram pressure, and young star clusters immediately upstream of the residual dust clouds that suggest star formation (SF) triggered by RPS. The distribution of the molecular gas is asymmetric in the galaxy, with no CO upstream and abundant CO downstream and in the inner tail region. A total amount of ∼5.5 × 109 M⊙ of molecular gas is detected in the galaxy and its tail. On the other hand, we do not detect any active SF in the X-ray and H α tails of ESO 137-002 with the HST data and place a limit on the SF efficiency in the tail. Hence, if selected by SF behind the galaxy in the optical or UV (e.g. surveys like GASP or using the Galex data), ESO 137-002 will not be considered a ‘jellyfish’ galaxy. Thus, galaxies like ESO 137-002 are important for our comprehensive understanding of RPS galaxies and the evolution of the stripped material. ESO 137-002 also presents a great example of an edge-on galaxy experiencing a nearly edge-on RPS wind.
more » « less- Award ID(s):
- 1714764
- NSF-PAR ID:
- 10379845
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 509
- Issue:
- 3
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- p. 3938-3956
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT Ram pressure stripping (RPS) is an important process to affect the evolution of cluster galaxies and their surrounding environment. We present a large MUSE mosaic for ESO 137-001 and its stripped tails, and study the detailed distributions and kinematics of the ionized gas and stars. The warm, ionized gas is detected to at least 87 kpc from the galaxy and splits into three tails. There is a clear velocity gradient roughly perpendicular to the stripping direction, which decreases along the tails and disappears beyond ∼45 kpc downstream. The velocity dispersion of the ionized gas increases to ∼80 km s−1 at ∼20 kpc downstream and stays flat beyond. The stars in the galaxy disc present a regular rotation motion, while the ionized gas is already disturbed by the ram pressure. Based on the observed velocity gradient, we construct the velocity model for the residual galactic rotation in the tails and discuss the origin and implication of its fading with distance. By comparing with theoretical studies, we interpreted the increased velocity dispersion as the result of the oscillations induced by the gas flows in the galaxy wake, which may imply an enhanced degree of turbulence there. We also compare the kinematic properties of the ionized gas and molecular gas from ALMA, which shows they are co-moving and kinematically mixed through the tails. Our study demonstrates the great potential of spatially resolved spectroscopy in probing the detailed kinematic properties of the stripped gas, which can provide important information for future simulations of RPS.
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