Star Formation in Isolated Dwarf Galaxies Hosting Tidal Debris: Extending the Dwarf–Dwarf Merger Sequence

Kado-Fong, Erin; Greene, Jenny E.; Greco, Johnny P.; Beaton, Rachael L.; Goulding, Andy D.; Johnson, Sean D.; Komiyama, Yutaka

doi:10.3847/1538-3881/ab6ef3

Cited by 40 publications

(26 citation statements)

References 74 publications

(101 reference statements)

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“…We also intend to explore the region outside our two 10-kpc spheres, and evaluate the role of tidal compression in driving extended star formation (Renaud et al 2014(Renaud et al , 2015. These investigations can also be expanded into (1) the dwarf regime, where gas content and SFE might be substantially different (Stierwalt et al 2015;Pearson et al 2016;Kado-Fong et al 2020;Martin et al 2020) ; (2) the high-redshift regime, where modifications to ISM content and structure (Bournaud et al 2011;Fensch et al 2017;Calabrò et al 2019) are accompanied by an increased frequency of merging (Bluck et al 2009(Bluck et al , 2012López-Sanjuan et al 2009;López-Sanjuan et al 2012Rodriguez-Gomez et al 2015;Mantha et al 2018;Duncan et al 2019); (3) minor mergers, which are expected to be more frequent (Villalobos & Helmi 2008Qu et al 2011;Kaviraj 2014;Martin et al 2018); and (4) the massive regime, where mixed and dry encounters tend to appear (Lin et al 2008;Stewart et al 2009; Lin et al 2010) -and where AGN feedback and environmental quenching processes are likely to collaborate in concert with tidal interactions, and assist galaxies in achieving their retirement into the passive sequence (Bluck et al 2014(Bluck et al , 2020.…”

Section: S U M M a Rymentioning

confidence: 99%

Spatially resolved star formation and fuelling in galaxy interactions

Moreno

Torrey

Ellison

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We investigate the spatial structure and evolution of star formation and the interstellar medium (ISM) in interacting galaxies. We use an extensive suite of parsec-scale galaxy merger simulations (stellar mass ratio = 2.5:1), which employs the ’Feedback In Realistic Environments-2’ model (fire-2). This framework resolves star formation, feedback processes, and the multi-phase structure of the ISM. We focus on the galaxy-pair stages of interaction. We find that close encounters substantially augment cool (HI) and cold-dense (H2) gas budgets, elevating the formation of new stars as a result. This enhancement is centrally-concentrated for the secondary galaxy, and more radially extended for the primary. This behaviour is weakly dependent on orbital geometry. We also find that galaxies with elevated global star formation rate (SFR) experience intense nuclear SFR enhancement, driven by high levels of either star formation efficiency (SFE) or available cold-dense gas fuel. Galaxies with suppressed global SFR also contain a nuclear cold-dense gas reservoir, but low SFE levels diminish SFR in the central region. Concretely, in the majority of cases, SFR-enhancement in the central kiloparsec is fuel-driven (55% for the secondary, 71% for the primary) - whilst central SFR-suppression is efficiency-driven (91% for the secondary, 97% for the primary). Our numerical predictions underscore the need of substantially larger, and/or merger-dedicated, spatially-resolved galaxy surveys - capable of examining vast and diverse samples of interacting systems - coupled with multi-wavelength campaigns aimed to capture their internal ISM structure.

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Section: S U M M a Rymentioning

confidence: 99%

Spatially resolved star formation and fuelling in galaxy interactions

Moreno

Torrey

Ellison

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The stellar masses measured by the SDSS team are derived using the Conroy et al (2009) Flexible Stellar Population Synthesis (FSPS) models with a Kroupa initial mass function (Kroupa 2001). In Kado-Fong et al (2020), we found that, for galaxies with both SDSS and GAMA spectroscopy, the SDSS stellar masses are higher than the GAMA stellar masses by a median of 0.08 dex and a median absolute deviation of 0.35 dex. We therefore reduce the masses derived from SDSS observations by 0.08 dex; it is however important to note that due to the width of our mass bins, including or excluding this shift does not impact this work.…”

Section: Initial Sample Selectionmentioning

confidence: 89%

Tracing the Intrinsic Shapes of Dwarf Galaxies out to Four Effective Radii: Clues to Low-Mass Stellar Halo Formation

Kado-Fong

Greene²,

Huang

et al. 2020

Preprint

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Though smooth, extended spheroidal stellar outskirts have long been observed around nearby dwarf galaxies, it is unclear whether dwarfs generically host an extended stellar halo. We use imaging from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) to measure the shapes of dwarf galaxies out to four effective radii for a sample of dwarfs at 0.005 < z < 0.2 and 10 7.0 < M /M < 10 9.6 . We find that dwarfs are slightly triaxial, with a B/A 0.75 (where the ellipsoid is characterized by three principle semi-axes constrained by C ≤ B ≤ A). At M > 10 8.5 M , the galaxies grow from thick disk-like near their centers towards the spheroidal extreme at four effective radii. We also see that although blue dwarfs are, on average, characterized by thinner discs than red dwarfs, both blue and red dwarfs grow more spheroidal as a function of radius. This relation also holds true for a comparison between field and satellite dwarfs. This uniform trend towards relatively spheroidal shapes as a function of radius is consistent with an in-situ formation mechanism for stellar outskirts around low-mass galaxies, in agreement with proposed models where star formation feedback produces round stellar outskirts around dwarfs.

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“…Finally, we cannot discard the possibility that the blue stream is associated with the possible star-forming dwarf galaxy DWARF-COMPANION, not with NGC 7241 itself. In recent years there has been a growing interest in detecting the presence of streams around low-mass galactic systems, i.e., LMC and SMC-like galaxies (e.g., Martínez-Delgado et al 2012;Kado-Fong et al 2020). The ΛCDM theory of a hierarchical universe predicts the presence of very lowmass halos interacting with dwarf galaxies in low-density environments (e.g., Guo et al 2011;Sales et al 2013).…”

Section: The Origin Of Blue Streams: Insights From Theory Simulations...mentioning

confidence: 99%

Once in a blue stream: Detection of recent star formation in the NGC 7241 stellar stream with MEGARA

Martínez–Delgado¹,

Roca-Fàbrega²,

Paz³

et al. 2021

Preprint

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The census of stellar tidal streams around nearby massive galaxies has significantly grown from recent deep imaging of the low-surface brightness sky. In this work we study the striking case of a blue narrow stream with a possible globular clusterlike progenitor around the Milky Way-size galaxy NGC 7241 and its foreground dwarf companion. We present a follow-up spectroscopic study of this stream based on data taken with the MEGARA instrument at the 10.4-m Gran Telescopio Canarias using the integral field spectroscopy mode. Although our data suggest that this compact object in the stream is actually a foreground Milky Way halo star, we detect emission lines overlapping a less compact, bluer and fainter blob of the stream that is clearly visible in both ultra-violet and optical deep images. From its heliocentric systemic radial velocity derived from the [O ]𝜆5007Å lines (𝑉 syst = 1548.58±1.80 km s −1 ) and new UV and optical broad-band photometry, we conclude that this over-density could be the actual core of the stream, with an absolute magnitude of M𝑔 ∼ -10 and a 𝑔 − 𝑟 = 0.08 ± 0.11, consistent with a remnant of a low-mass dwarf satellite undergoing a current episode of star formation. From the width of the stream and assuming a circular orbit, we calculate that the progenitor mass is between 6.4 × 10 6 M − 2.7 × 10 7 M , which is typical of a dwarf galaxy, but its mass could be substantially lower if the stream is on a very radial orbit. These estimates also suggest that this is one of the lowest mass streams detected so far beyond the Local Group. We find that blue stellar streams containing star formation regions are commonly predicted by high-resolution cosmological simulations of galaxies lighter than the Milky Way. This scenario is consistent with the processes explaining the bursty star formation history of some dwarf satellites, which are followed by a gas depletion and a fast quenching once they enter within the virial radius of their host galaxies for the first time. Thus, it is likely that the stream's progenitor is suffering a star-formation burst comparable to those that have shaped the star-formation history of several Local Group dwarfs in the last few Gigayears.

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Star Formation in Isolated Dwarf Galaxies Hosting Tidal Debris: Extending the Dwarf–Dwarf Merger Sequence

Cited by 40 publications

References 74 publications

Spatially resolved star formation and fuelling in galaxy interactions

Spatially resolved star formation and fuelling in galaxy interactions

Tracing the Intrinsic Shapes of Dwarf Galaxies out to Four Effective Radii: Clues to Low-Mass Stellar Halo Formation

Once in a blue stream: Detection of recent star formation in the NGC 7241 stellar stream with MEGARA

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