Chemical Abundances of Seven Irregular and Three Tidal Dwarf Galaxies in the M81 Group

Croxall, K. V.; Zee, Liese van; Lee, Henry; Skillman, Evan D.; Boquien, M.; Côté, Stéphanie; Kennicutt, Robert C.; Miller, Bryan W.

doi:10.1088/0004-637x/705/1/723

Cited by 132 publications

(176 citation statements)

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“…The emission lines, therefore, probably originate from gas similar to that found in objects of medium metallicity and low excitation. It is also similar to the Croxall et al (2009) HII regions in tidal dwarf galaxies. Second, the ICL star population is not very old, of the order of 2.3 × 10 9 yr, compared to the BCG population of 9.3 × 10 9 yr (close to estimates of Cui et al 2014, see their Fig.…”

Section: Discussionsupporting

confidence: 65%

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The XXL Survey

Adami

Pompei

Sadibekova

et al. 2016

A&A

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Aims. Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies and their subsequent dispersal into the intracluster medium. Gas hydrodynamical effects can additionally strip gas and dust from galaxies; both gas and stars contribute to intracluster light (ICL). The properties of the ICL can therefore help constrain the physical processes at work in clusters by serving as a fossil record of the interaction history. Methods. The present study is designed to characterise this ICL for the first time in a ∼10 14 M and z ∼ 0.53 cluster of galaxies from imaging and spectroscopic points of view. By applying a wavelet-based method to CFHT Megacam and WIRCAM images, we detect significant quantities of diffuse light and are able to constrain their spectral energy distributions. These sources were then spectroscopically characterised with ESO Multi Unit Spectroscopic Explorer (MUSE) spectroscopic data. MUSE data were also used to compute redshifts of 24 cluster galaxies and search for cluster substructures.Results. An atypically large amount of ICL, equivalent in i to the emission from two brightest cluster galaxies, has been detected in this cluster. Part of the detected diffuse light has a very weak optical stellar component and apparently consists mainly of gas emission, while other diffuse light sources are clearly dominated by old stars. Furthermore, emission lines were detected in several places of diffuse light. Our spectral analysis shows that this emission likely originates from low-excitation parameter gas. Globally, the stellar contribution to the ICL is about 2.3 × 10 9 yr old even though the ICL is not currently forming a large number of stars. On the other hand, the contribution of the gas emission to the ICL in the optical is much greater than the stellar contribution in some regions, but the gas density is likely too low to form stars. These observations favour ram pressure stripping, turbulent viscous stripping, or supernovae winds as the origin of the large amount of intracluster light. Since the cluster appears not to be in a major merging phase, we conclude that ram pressure stripping is the most plausible process that generates the observed ICL sources. Conclusions. This is one of the first times that we are able to spectroscopically study diffuse light in such a distant and massive cluster, and it demonstrates the potential of MUSE observations for such studies.

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Section: Discussionsupporting

confidence: 65%

“…Any of their models with metallicity larger than 1 predict R23 values at least five times smaller than what we observe in the ELDL source. We also compared our results with the work of Croxall et al (2009) on HII regions in dwarf galaxies of the M81 group. From their Fig.…”

Section: Eldl Sourcementioning

confidence: 91%

The XXL Survey

Adami

Pompei

Sadibekova

et al. 2016

A&A

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“…Dwarf galaxies with similarly high metallicity for their luminosity have also been observed in the M 81 group, and it was also suggested that they formed during galaxy interactions in the group from tidal debris (e.g. Croxall et al 2009). Here we aim to test this scenario by studying the integrated properties of the IKN GCs.…”

Section: Introductionmentioning

confidence: 89%

Optical-near-IR analysis of globular clusters in the IKN dwarf spheroidal: a complex star formation history

Tudorica

Georgiev

Chies-Santos

2015

A&A

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Context. Age, metallicity, and spatial distribution of globular clusters (GCs) provide a powerful tool for reconstructing major starformation episodes in galaxies. IKN is a faint dwarf spheroidal (dSph) in the M 81 group of galaxies. It contains five old GCs, which makes it the galaxy with the highest known specific frequency (S N = 126). Aims. We estimate the photometric age, metallicity, and spatial distribution of the poorly studied IKN GCs. We search SDSS for GC candidates beyond the HST/ACS field of view, which covers half of IKN. Methods. To break the age-metallicity degeneracy in the V −I colour, we used WHT/LIRIS K S -band photometry and derived photometric ages and metallicities by comparison with SSP models in the V, I, K s colour space. Results. IKN GCs' V IK s colours are consistent with old ages (≥8 Gyr) and a metallicity distribution with a higher mean than is typical for such a dSph ([Fe/H] −1.4 +0.6 −0.2 dex). Their photometric mass range (0.5 < M GC < 4 × 10 5 M ) implies an unusually high mass ratio between GCs and field stars, of 10.6%. Mixture model analysis of the RGB field stars' metallicity suggests that 72% of the stars may have formed together with the GCs. Using the most massive GC−SFR relation, we calculated a star formation rate (SFR) of ∼10 M /yr during its formation epoch. We note that the more massive GCs are closer to the galaxy photometric centre. IKN GCs also appear spatially aligned along a line close to the major axis of the IKN and nearly orthogonal to the plane of spatial distribution of galaxies in the M 81 group. We identify one new IKN GC candidate based on colour and the PSF analysis of the SDSS data. Conclusions. The evidence of i) broad and high metallicity distribution of the field IKN RGB stars and its GCs, ii) high fraction, and iii) spatial alignment of IKN GCs supports a scenario for tidally triggered, complex IKN's star formation history in the context of interactions with galaxies in the M 81 group.

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“…Spectroscopy data (line intensities and EW (Hβ)) for IC 2574 are taken from Croxall et al (2009), data for NGC 628 are partly from Gusev et al (2012) and partly from van Zee et al (1998), data for NGC 6946 are taken from Gusev, Sakhibov & Dodonov (2013), and NGC 925 and NGC 3184 data are taken from van Zee et al (1998). Finally, NGC 3621 data are from Ryder (1995).…”

Section: Spectroscopic Datamentioning

confidence: 99%

Optical and infrared emission of H ii complexes as a clue to the PAH life cycle

Khramtsova¹,

Wiebe²,

Lozinskaya³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present an analysis of optical spectroscopy and infrared aperture photometry of more than 100 H ii complexes in nine galaxies. Spectra obtained with the 6-m telescope of SAO RAS are used along with archival data from Spitzer and several ground-based telescopes to infer a strength of polycyclic aromatic hydrocarbon (PAH) emission, age, properties of the UV radiation field, and metallicity of studied H ii complexes. Physical properties (age, radiation field parameters, metallicity) are related to the F 8 /F 24 ratio used as a proxy for the PAH abundance in order to reveal factors that may influence the PAH evolution in H ii complexes. The well-known correlation between the F 8 /F 24 ratio and metallicity is confirmed in the studied complexes. The infrared flux ratio also correlates with the [O iii]λ5007/Hβ ratio which is often considered as an indicator of the radiation field hardness, but this correlation seems to be a mere reflection of a correlation between [O iii]λ5007/Hβ and metallicity. In separate metallicity bins, the F 8 /F 24 ratio is found to correlate with an age of an H ii complex, which is estimated from the equivalent width of Hβ line. The correlation is positive for low metallicity complexes and negative for high metallicity complexes. Analysing various mechanisms of PAH formation and destruction in the context of found correlations, we suggest that PAH abundance is likely altered by the UV radiation within H ii complexes, but this is not necessarily due to their destruction. If PAHs can also form in H ii complexes due to some processes like aromatisation, photodestruction, shattering and sputtering of very small grains, the net F 8 /F 24 ratio is determined by a balance between all these processes that can be different at different metallicities.

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Chemical Abundances of Seven Irregular and Three Tidal Dwarf Galaxies in the M81 Group

Cited by 132 publications

References 81 publications

The XXL Survey

The XXL Survey

Optical-near-IR analysis of globular clusters in the IKN dwarf spheroidal: a complex star formation history

Optical and infrared emission of H ii complexes as a clue to the PAH life cycle

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