A deep, wide-field study of Holmberg II with Suprime-Cam: evidence for ram pressure stripping

Bernard, Edouard J.; Ferguson, Annette M. N.; Barker, M. K.; Irwin, M. J.; Jablonka, P.; Arimoto, N.

doi:10.1111/j.1365-2966.2012.22025.x

Cited by 18 publications

(23 citation statements)

References 67 publications

(87 reference statements)

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“…The morphology of atomic hydrogen in this galaxy is extremely inhomogeneous. The observed large-scale cometlike asymmetry of the H i disc is probably caused by the ram pressure stripping due to the hot intragroup medium (Bernard et al 2012). The H i distribution in the galaxy Oh et al (2011) c Updated Local Volume galaxies database (Karachentsev et al 2013, http://www.sao.ru/lv/lvgdb/) d Moustakas et al (2010) e Sánchez-Salcedo et al (2014) disc represents a large number of contiguous giant supershells and 'holes' (most representable of them are shown in Fig.…”

Section: Multi-wavelength Overview Of Holmberg IImentioning

confidence: 99%

Complexes of triggered star formation in supergiant shell of Holmberg II

Egorov

Lozinskaya

Моисеев

et al. 2016

Mon. Not. R. Astron. Soc.

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We report a detailed analysis of all regions of current star formation in the walls of the supergiant H i shell (SGS) in the galaxy Holmberg II based on observations with a scanning Fabry-Perot interferometer at the 6-m SAO RAS telescope. We compare the structure and kinematics of ionized gas with that of atomic hydrogen and with the stellar population of the SGS. Our deep Hα images and archival images taken by the HST demonstrate that current star formation episodes are larger and more complicated than previously thought: they represent unified star-forming complexes with sizes of several hundred pc rather than 'chains' of separate bright nebulae in the walls of the SGS. The fact that we are dealing with unified complexes is evidenced by identified faint shell-like structures of ionized and neutral gas which connect several distinct bright H ii regions. Formation of such complexes is due to the feedback of stars with very inhomogeneous ambient gas in the walls of the SGS. The arguments supporting an idea about the triggering of star formation in SGS by the H i supershells collision are presented. We also found a faint ionized supershell inside the H i SGS expanding with a velocity of no greater than 10 − 15 km s −1 . Five OB stars located inside the inner supershell are sufficient to account for its radiation, although a possibility of leakage of ionizing photons from bright H ii regions is not ruled out as well.

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Section: Multi-wavelength Overview Of Holmberg IImentioning

confidence: 99%

Complexes of triggered star formation in supergiant shell of Holmberg II

Egorov

Lozinskaya

Моисеев

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Color-magnitude diagrams are a widely used tool to study the stellar fossil records of nearby galaxies (Monelli et al (2010), Rubele et al (2011), Bernard et al (2012. This approach is currently limited to the local Universe, for which resolved photometric data is accessible with the currently available instruments.…”

Section: Constructing Realistic Color-magnitude Diagramsmentioning

confidence: 99%

“Observations” of simulated dwarf galaxies

Rathi

Rijcke

Gallart

et al. 2020

A&A

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Context. Apparent deviations between properties of dwarf galaxies from observations and simulations are known to exist, such as the “Missing Dwarfs” problem, the too-big-to-fail problem, and the cusp-core problem, to name a few. Recent studies have shown that these issues can at least be partially resolved by taking into account the systematic differences between simulations and observations. Aims. This work aims to investigate and address any systematic differences affecting the comparison of simulations with observations. Methods. To this aim, we analyzed a set of 24 realistically simulated Models of Realistic dwarfs In Action (MoRIA) dwarf galaxies in an observationally motivated way. We first constructed “observed” color-magnitude diagrams (CMDs) of the simulated dwarf galaxies in the typically used V- and I-bands. Then we used the synthetic CMD-fitting method to recover their star-formation histories (SFHs) from their observed CMDs. These solved SFHs were then directly compared to the true SFHs from the simulation star-particle data, mainly in terms of the star-formation rate (SFR) and the age-metallicity relation (AMR). We also applied a dust extinction prescription to the simulation data to produce observed CMDs affected by dust in the star-forming regions. Since future facilities, such as the James Webb Space Telescope and the European Extremely Large Telescope, will focus on the (near)-infrared rather than the optical, we also constructed and analyzed CMDs consisting of the I- and H- bands. Results. We find a very good agreement between the recovered and the true SFHs of all the simulated dwarf galaxies in our sample, from the synthetic CMD analysis of their V − I versus I as well as the I − H versus H CMDs. Dust leads to an underestimation of the SFR during the last few hundred million years, with the strength and duration of the effect dependent on the dust content. Overall, our analysis indicates that quantities like SFR and AMR derived from the photometric observations of galaxies are directly comparable to their simulated counterparts, thus eliminating any systematic bias in the comparison of simulations and observations.

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“…These five illustrative examples provide a direct grasp of our ability in resolving individual stars as a function of galaxy distance. Previous studies have demonstrated that individual RGB stars can be resolved from the ground in the least crowded galaxy outskirts up to distances of ∼4-5 Mpc, provided that the seeing is as good as 0.8 (e.g Bernard et al 2012;Okamoto et al 2015;Crnojević et al 2016). The CMDs obtained from our analysis confirm these results, showing that RGB stars, tracing the underlying old (>1-2 Gyr) stellar population, are reached up to targets at D 5 Mpc, while only brighter stellar phases (young main sequence stars, blue and red supergiants, asymptotic giant branch stars) are accessible at larger distances.…”

Section: Color-magnitude Diagramsmentioning

confidence: 99%

“…The CMDs presented in section 7 provide a powerful diagnostic to separate stars belonging to the target galaxies from background and foreground contaminants. This technique has been extensively used in the literature to identify low surface brightness stellar streams, satellites, and extended stellar halos in galaxies within the Local Group and beyond (e.g., Belokurov et al 2006;Bernard et al 2012;Bonaca et al 2012;Beccari et al 2014;Greggio et al 2014;Martin et al 2014;Roderick et al 2015;Belokurov & Koposov 2016;Crnojević et al 2016;Higgs et al 2016;Mackey et al 2016;Tanaka et al 2017;McConnachie et al 2018;Pucha et al 2019). This approach allows to typically reach much fainter surface brightness structures than from the integrated light, down to values as low as 31-35 mag arcsec −2 , depending on the faintest evolutionary phase sampled by the CMD.…”

Section: Stellar Density Mapsmentioning

confidence: 99%

The Smallest Scale of Hierarchy Survey (SSH). I. Survey Description

Annibali,

Beccari,

Bellazzini

et al. 2019

Preprint

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The Smallest Scale of Hierarchy (SSH) survey is an ongoing strategic large program at the Large Binocular Telescope, aimed at the detection of faint stellar streams and satellites around 45 late-type dwarf galaxies located in the Local Universe within 10 Mpc. SSH exploits the wide-field, deep photometry provided by the Large Binocular Cameras in the two wide filters g and r. This paper describes the survey, its goals, and the observational and data reduction strategies. We present preliminary scientific results for five representative cases (UGC 12613, NGC 2366, UGC 685, NGC 5477 and UGC 4426) covering the whole distance range spanned by the SSH targets. We reach a surface brightness limit as faint as µ(r) ∼ 31 mag arcsec −2 both for targets closer than 4−5 Mpc, which are resolved into individual stars, and for more distant targets through the diffuse light. Our analysis reveals the presence of extended low surface brightness stellar envelopes around the dwarfs, reaching farther out than what traced by the integrated light, and as far out as, or even beyond, the observed H I disk. Stellar streams, arcs, and peculiar features are detected in some cases, indicating possible perturbation, accretion, or merging events. We also report on the discovery of an extreme case of Ultra Diffuse Galaxy (µ g (0) = 27.9 mag/arcsec 2 ) in the background of one of our targets, to illustrate the power of the survey in revealing extremely low surface brightness systems.

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A deep, wide-field study of Holmberg II with Suprime-Cam: evidence for ram pressure stripping

Cited by 18 publications

References 67 publications

Complexes of triggered star formation in supergiant shell of Holmberg II

Complexes of triggered star formation in supergiant shell of Holmberg II

“Observations” of simulated dwarf galaxies

The Smallest Scale of Hierarchy Survey (SSH). I. Survey Description

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