The SAMI–Fornax Dwarfs Survey – III. Evolution of [α/Fe] in dwarfs, from Galaxy Clusters to the Local Group

Romero-Gómez, J; Peletier, R. F.; Aguerri, J. A. L.; Mieske, S.; Scott, Nicholas; Bland‐Hawthorn, J.; Bryant, Julia J.; Croom, S. M.; Eftekhari, F. Sara; Falcón-Barroso, J.; Hilker, M.; Ven, Glenn van de; Venhola, Aku

doi:10.1093/mnras/stad953

Cited by 11 publications

(2 citation statements)

References 141 publications

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“…Any relative changes between the g and r profiles within R e (see also the g − r colour maps presented in Raj et al 2020), or differences compared to the average g − r colour, are significantly smaller than the uncertainty on dust correction or the spread of the ageing sequence or the expected variations in Hα. 3 shows, we detect [O III] in NGC 1326B, FCC 35 (central and outer regions), and in NGC 1317 and FCC 46 (central region; see also Romero-Gómez et al 2023), implying -at least qualitatively -that star formation is ongoing or recent in these galaxies. These are the galaxies that are removed from the secular evolution sequence (defined as the continuous evolution of a galaxy driven by the consumption of gas through uninterrupted star formation until quiescence is reached) as discussed in Section 4.2.…”

Section: G − R Colours From the Fds Surveymentioning

confidence: 60%

“…This is in contrast to 'ageing' which describes the normal star formation sequence in which a blue galaxy will eventually end up as a red galaxy with old stellar serving programmes across different wavelength regimes with Southern-hemisphere facilities. Campaigns include deep optical imaging from the Fornax Deep Survey (FDS; Iodice et al 2016;Venhola et al 2018;Peletier et al 2020), deep HI observations from the MeerKAT Fornax Survey (MFS; Serra et al 2016Serra et al , 2023, observations with ALMA (Zabel et al 2019;Morokuma-Matsui et al 2022), integral field spectroscopy from the Fornax3D Survey (F3D; Sarzi et al 2018), as well as the SAMI-Fornax Dwarf Survey (Romero-Gómez et al 2023).…”

Section: Introductionmentioning

confidence: 99%

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The star formation histories of galaxies in different stages of pre-processing in the Fornax A group

Loubser,

Mosia,

Serra

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We study the recent star formation histories of 10 galaxies in the Fornax A galaxy group, on the outskirts of the Fornax cluster. The group galaxies are gas-rich, and their neutral atomic hydrogen (H i) was studied in detail with observations from the MeerKAT telescope. This allowed them to be classified into different stages of pre-processing (early, ongoing, advanced). We use long-slit spectra obtained with the South African Large Telescope (SALT) to analyse stellar population indicators to constrain quenching time-scales and to compare these to the H i gas content of the galaxies. The H α equivalent width, EW(H α), suggest that the pre-processing stage is closely related to the recent (<10 Myr) specific Star Formation Rate (sSFR). The early-stage galaxy (NGC 1326B) is not yet quenched in its outer parts, while the ongoing-stage galaxies mostly have a distributed population of very young stars, though less so in their outer parts. The galaxies in the advanced stage of pre-processing show very low recent sSFR in the outer parts. Our results suggest that NGC 1326B, FCC 35, and FCC 46 underwent significantly different histories from secular evolution during the last Gyr. The fact that most galaxies are on the secular evolution sequence implies that pre-processing has a negligible effect on these galaxies compared to secular evolution. We find EW(H α) to be a useful tool for classifying the stage of pre-processing in group galaxies. The recent sSFR and H i morphology show that galaxies in the Fornax A vicinity are pre-processing from the outside in.

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Section: G − R Colours From the Fds Surveymentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

The star formation histories of galaxies in different stages of pre-processing in the Fornax A group

Loubser,

Mosia,

Serra

et al. 2023

Monthly Notices of the Royal Astronomical Society

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The MeerKAT Fornax Survey

Kleiner¹,

Serra²,

Maccagni³

et al. 2023

A&A

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We present MeerKAT Fornax Survey atomic hydrogen (H I) observations of the dwarf galaxies located in the central ∼2.5 × 4 deg2 of the Fornax galaxy cluster (Rvir ∼2°). The H I images presented in this work have a 3σ column density sensitivity between 2.7 and 50 × 1018 cm−2 over 25 km s−1 for spatial resolution between 4 and 1 kpc. We are able to detect an impressive MHI = 5 × 105 M⊙ 3σ point source with a line width of 50 km s−1 at a distance of 20 Mpc. We detected H I in 17 out of the 304 dwarfs in our field, with 14 out of the 36 late-type dwarfs (LTDs) and three out of the 268 early-type dwarfs (ETDs). The H I-detected LTDs have likely just joined the cluster and are on their first infall as they are located at large clustocentric radii, with comparable MHI and mean stellar surface brightness at fixed luminosity as blue, star-forming LTDs in the field. By contrast, the H I-detected ETDs have likely been in the cluster longer than the LTDs and acquired their H I through a recent merger or accretion from nearby H I. Eight of the H I-detected LTDs host irregular or asymmetric H I emission and disturbed or lopsided stellar emission. There are two clear cases of ram pressure shaping the H I, with the LTDs displaying compressed H I on the side closest to the cluster centre and a one-sided, starless tail pointing away from the cluster centre. The H I-detected dwarfs avoid the most massive potentials (i.e. cluster centre and massive galaxies), consistent with massive galaxies playing an active role in the removal of H I. We created a simple toy model to quantify the timescale of H I stripping in the cluster by reproducing the observed Mr′–MHI relation. We find that a MHI = 108 M⊙ dwarf is stripped in ∼240 Myr. The model is consistent with our observations, where low-mass LTDs are directly stripped of their H I from a single encounter and more massive LTDs can harbour a disturbed H I morphology due to longer times or multiple encounters being required to fully strip their H I. This is the first time dwarf galaxies with MHI ≲ 1 × 106 M⊙ have been detected and resolved beyond the local group and in a galaxy cluster.

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Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra-I cluster

Iodice,

Hilker,

Doll

et al. 2023

A&A

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Looking into the faintEst WIth MUSE (LEWIS) is an ESO large observing programme that aims at obtaining the first homogeneous integral-field spectroscopic survey of 30 extremely low-surface-brightness (LSB) galaxies in the Hydra I cluster of galaxies with MUSE at ESO-VLT. The majority of LSB galaxies in the sample (22 in total) are ultra-diffuse galaxies (UDGs). Data acquisition started in December 2021 and is expected to be concluded by March 2024. Up to June 2023, 29 targets were observed and the redshift has been derived for 20 of them. The distribution of systemic velocities Vsys ranges between 2317 km s−1 and 5198 km s−1 and is centred on the mean velocity of Hydra I (Vsys = 3683 ± 46 km s−1). Considering the mean velocity and the velocity dispersion of the cluster (σcluster ∼ 700 km s−1), 17 out of 20 targets are confirmed cluster members. The three objects with velocities of greater than 2σcluster away from the cluster mean velocity could be two background galaxies and one foreground galaxy. To assess the quality of the data and demonstrate the feasibility of the science goals, we report the preliminary results obtained for one of the sample galaxies, UDG11. For this target, we (i) derived the stellar kinematics, including the two-dimensional maps of line-of-sight velocity and velocity dispersion, (ii) constrained age and metallicity, and (iii) studied the globular cluster (GC) population hosted by the UDG. Results are compared with the available measurements for UDGs and dwarf galaxies in the literature. By fitting the stacked spectrum inside one effective radius, we find that UDG11 has a velocity dispersion of σ = 20 ± 8 km s−1 and is old (10 ± 1 Gyr), metal-poor ([M/H] = −1.17 ± 0.11 dex), and has a total dynamical mass-to-light ratio of M/LV ∼ 14, which is comparable to those observed for classical dwarf galaxies. The spatially resolved stellar kinematics maps suggest that UDG11 does not show a significant velocity gradient along either its major or minor photometric axis, and the average value of the velocity dispersion is ⟨σ⟩e = 27 ± 8 km s−1. We find two GCs kinematically associated with UDG11. The estimated total number of GCs in UDG11 – corrected for the spectroscopic completeness limit – is NGC = 5.9−1.8+2.2, which corresponds to a GC-specific frequency of SN = 8.4−2.7+3.2.

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The SAMI–Fornax Dwarfs Survey – III. Evolution of [α/Fe] in dwarfs, from Galaxy Clusters to the Local Group

Cited by 11 publications

References 141 publications

The star formation histories of galaxies in different stages of pre-processing in the Fornax A group

The star formation histories of galaxies in different stages of pre-processing in the Fornax A group

The MeerKAT Fornax Survey

Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra-I cluster

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