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A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies

Zanella, A; Le Floc’h, E; Harrison, CM; Daddi, E; Bernhard, E; Gobat, R; Strazzullo, V; Valentino, F; Cibinel, A; Sánchez Almeida, J; Kohandel, M; Fensch, J; Behrendt, M; Burkert, A; Onodera, M; Bournaud, F; Scholtz, J

A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies Thumbnail


Authors

A Zanella

E Le Floc’h

CM Harrison

E Daddi

E Bernhard

R Gobat

V Strazzullo

F Valentino

A Cibinel

J Sánchez Almeida

M Kohandel

J Fensch

M Behrendt

A Burkert

M Onodera

F Bournaud

J Scholtz



Abstract

We investigate the contribution of clumps and satellites to the galaxy mass assembly. We analysed spatially resolved HubbleSpace Telescope observations (imaging and slitless spectroscopy) of 53 star-forming galaxies at z ∼ 1–3. We created continuum and emission line maps and pinpointed residual ‘blobs’ detected after subtracting the galaxy disc. Those were separated into compact (unresolved) and extended (resolved) components. Extended components have sizes ∼2 kpc and comparable stellar mass and age as the galaxy discs, whereas the compact components are 1.5 dex less massive and 0.4 dex younger than the discs. Furthermore, the extended blobs are typically found at larger distances from the galaxy barycentre than the compact ones. Prompted by these observations and by the comparison with simulations, we suggest that compact blobs are in situ formed clumps, whereas the extended ones are accreting satellites. Clumps and satellites enclose, respectively, ∼20 per cent and ≲80 per cent of the galaxy stellar mass, ∼30 per cent and ∼20 per cent of its star formation rate. Considering the compact blobs, we statistically estimated that massive clumps (M⋆ ≳ 109 M⊙) have lifetimes of ∼650 Myr, and the less massive ones (108 < M⋆ < 109 M⊙) of ∼145 Myr. This supports simulations predicting long-lived clumps (lifetime ≳ 100 Myr). Finally, ≲30 per cent (13 per cent) of our sample galaxies are undergoing single (multiple) merger(s), they have a projected separation ≲10 kpc, and the typical mass ratio of our satellites is 1:5 (but ranges between 1:10 and 1:1), in agreement with literature results for close pair galaxies.

Citation

Zanella, A., Le Floc’h, E., Harrison, C., Daddi, E., Bernhard, E., Gobat, R., …Scholtz, J. (2019). A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies. Monthly Notices of the Royal Astronomical Society, 489(2), 2792-2818. https://doi.org/10.1093/mnras/stz2099

Journal Article Type Article
Acceptance Date Jul 26, 2019
Online Publication Date Aug 5, 2019
Publication Date Oct 31, 2019
Deposit Date Oct 24, 2019
Publicly Available Date Oct 25, 2019
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 489
Issue 2
Pages 2792-2818
DOI https://doi.org/10.1093/mnras/stz2099

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Royal Astronomical Society published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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