Deciphering an evolutionary sequence of merger stages in infrared-luminous starburst galaxies at z ∼ 0.7

A. Calabrò*, E. Daddi, A. Puglisi, E. Oliva, R. Gobat, P. Cassata, R. Amorín, N. Arimoto, M. Boquien, R. Carraro, I. Delvecchio, E. Ibar, S. Jin, S. Juneau, D. Liu, M. Onodera, F. Mannucci, H. Méndez-Hernández, G. Rodighiero, F. Valentino & 1 others A. Zanella

*Corresponding author for this work

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Abstract

Based on optical and near-IR Magellan FIRE spectra of 25 starburst galaxies at 0.5 < z< 0.9, a recent publication showed that their attenuation properties can be explained by a single-parameter sequence of total obscurations ranging from A V = 2 to A V = 30 toward the starburst core centers in a mixed stars and dust configuration. We investigate here the origin of this sequence for the same sample. We show that total attenuations anticorrelate with the starburst sizes in radio (3 GHz) with a significance larger than 5σ and a scatter of 0.26 dex. More obscured and compact starbursts also show enhanced N2 (=[NII]/Hα) ratios and larger line velocity widths that we attribute to an increasing shock contribution toward later merger phases, driven by deeper gravitational potential wells at the coalescence. Additionally, the attenuation is also linked to the equivalent width (EW) of hydrogen recombination lines, which is sensitive to the luminosity weighted age of the relatively unobscured stellar populations. Overall, the correlations among A V, tot , radio size, line width, N2 and EW of Balmer and Paschen lines converge toward suggesting an evolutionary sequence of merger stages: all of these quantities are likely to be good time-tracers of the merger phenomenon, and their large spanned range appears to be characteristic of the different merger phases. Half of our sample at higher obscurations have radio sizes approximately 3 times smaller than early type galaxies at the same redshift, suggesting that, in analogy with local ultraluminous infrared galaxies (ULIRGs), these cores cannot be directly forming elliptical galaxies. Finally, we detect mid-IR AGN torus for half of our sample and additional X-ray emission for 6 starbursts; intriguingly, the latter have systematically more compact sizes, suggestive of emerging AGNs toward later merger stages, possibly precursors of a later QSO phase.

Original languageEnglish
Article numberA64
JournalAstronomy and Astrophysics
Volume623
Number of pages31
ISSN0004-6361
DOIs
Publication statusPublished - 2019

Bibliographical note

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Keywords

  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: interactions
  • Galaxies: star formation
  • Galaxies: starburst

Cite this

Calabrò, A. ; Daddi, E. ; Puglisi, A. ; Oliva, E. ; Gobat, R. ; Cassata, P. ; Amorín, R. ; Arimoto, N. ; Boquien, M. ; Carraro, R. ; Delvecchio, I. ; Ibar, E. ; Jin, S. ; Juneau, S. ; Liu, D. ; Onodera, M. ; Mannucci, F. ; Méndez-Hernández, H. ; Rodighiero, G. ; Valentino, F. ; Zanella, A. / Deciphering an evolutionary sequence of merger stages in infrared-luminous starburst galaxies at z ∼ 0.7. In: Astronomy and Astrophysics. 2019 ; Vol. 623.
@article{78f005bfe3094985ae3903e4b00b9882,
title = "Deciphering an evolutionary sequence of merger stages in infrared-luminous starburst galaxies at z ∼ 0.7",
abstract = "Based on optical and near-IR Magellan FIRE spectra of 25 starburst galaxies at 0.5 < z< 0.9, a recent publication showed that their attenuation properties can be explained by a single-parameter sequence of total obscurations ranging from A V = 2 to A V = 30 toward the starburst core centers in a mixed stars and dust configuration. We investigate here the origin of this sequence for the same sample. We show that total attenuations anticorrelate with the starburst sizes in radio (3 GHz) with a significance larger than 5σ and a scatter of 0.26 dex. More obscured and compact starbursts also show enhanced N2 (=[NII]/Hα) ratios and larger line velocity widths that we attribute to an increasing shock contribution toward later merger phases, driven by deeper gravitational potential wells at the coalescence. Additionally, the attenuation is also linked to the equivalent width (EW) of hydrogen recombination lines, which is sensitive to the luminosity weighted age of the relatively unobscured stellar populations. Overall, the correlations among A V, tot , radio size, line width, N2 and EW of Balmer and Paschen lines converge toward suggesting an evolutionary sequence of merger stages: all of these quantities are likely to be good time-tracers of the merger phenomenon, and their large spanned range appears to be characteristic of the different merger phases. Half of our sample at higher obscurations have radio sizes approximately 3 times smaller than early type galaxies at the same redshift, suggesting that, in analogy with local ultraluminous infrared galaxies (ULIRGs), these cores cannot be directly forming elliptical galaxies. Finally, we detect mid-IR AGN torus for half of our sample and additional X-ray emission for 6 starbursts; intriguingly, the latter have systematically more compact sizes, suggestive of emerging AGNs toward later merger stages, possibly precursors of a later QSO phase.",
keywords = "Galaxies: evolution, Galaxies: formation, Galaxies: high-redshift, Galaxies: interactions, Galaxies: star formation, Galaxies: starburst",
author = "A. Calabr{\`o} and E. Daddi and A. Puglisi and E. Oliva and R. Gobat and P. Cassata and R. Amor{\'i}n and N. Arimoto and M. Boquien and R. Carraro and I. Delvecchio and E. Ibar and S. Jin and S. Juneau and D. Liu and M. Onodera and F. Mannucci and H. M{\'e}ndez-Hern{\'a}ndez and G. Rodighiero and F. Valentino and A. Zanella",
note = "Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.",
year = "2019",
doi = "10.1051/0004-6361/201834522",
language = "English",
volume = "623",
journal = "Astronomy & Astrophysics",
issn = "0004-6361",
publisher = "E D P Sciences",

}

Calabrò, A, Daddi, E, Puglisi, A, Oliva, E, Gobat, R, Cassata, P, Amorín, R, Arimoto, N, Boquien, M, Carraro, R, Delvecchio, I, Ibar, E, Jin, S, Juneau, S, Liu, D, Onodera, M, Mannucci, F, Méndez-Hernández, H, Rodighiero, G, Valentino, F & Zanella, A 2019, 'Deciphering an evolutionary sequence of merger stages in infrared-luminous starburst galaxies at z ∼ 0.7', Astronomy and Astrophysics, vol. 623, A64. https://doi.org/10.1051/0004-6361/201834522

Deciphering an evolutionary sequence of merger stages in infrared-luminous starburst galaxies at z ∼ 0.7. / Calabrò, A.; Daddi, E.; Puglisi, A.; Oliva, E.; Gobat, R.; Cassata, P.; Amorín, R.; Arimoto, N.; Boquien, M.; Carraro, R.; Delvecchio, I.; Ibar, E.; Jin, S.; Juneau, S.; Liu, D.; Onodera, M.; Mannucci, F.; Méndez-Hernández, H.; Rodighiero, G.; Valentino, F.; Zanella, A.

In: Astronomy and Astrophysics, Vol. 623, A64, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Deciphering an evolutionary sequence of merger stages in infrared-luminous starburst galaxies at z ∼ 0.7

AU - Calabrò, A.

AU - Daddi, E.

AU - Puglisi, A.

AU - Oliva, E.

AU - Gobat, R.

AU - Cassata, P.

AU - Amorín, R.

AU - Arimoto, N.

AU - Boquien, M.

AU - Carraro, R.

AU - Delvecchio, I.

AU - Ibar, E.

AU - Jin, S.

AU - Juneau, S.

AU - Liu, D.

AU - Onodera, M.

AU - Mannucci, F.

AU - Méndez-Hernández, H.

AU - Rodighiero, G.

AU - Valentino, F.

AU - Zanella, A.

N1 - Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PY - 2019

Y1 - 2019

N2 - Based on optical and near-IR Magellan FIRE spectra of 25 starburst galaxies at 0.5 < z< 0.9, a recent publication showed that their attenuation properties can be explained by a single-parameter sequence of total obscurations ranging from A V = 2 to A V = 30 toward the starburst core centers in a mixed stars and dust configuration. We investigate here the origin of this sequence for the same sample. We show that total attenuations anticorrelate with the starburst sizes in radio (3 GHz) with a significance larger than 5σ and a scatter of 0.26 dex. More obscured and compact starbursts also show enhanced N2 (=[NII]/Hα) ratios and larger line velocity widths that we attribute to an increasing shock contribution toward later merger phases, driven by deeper gravitational potential wells at the coalescence. Additionally, the attenuation is also linked to the equivalent width (EW) of hydrogen recombination lines, which is sensitive to the luminosity weighted age of the relatively unobscured stellar populations. Overall, the correlations among A V, tot , radio size, line width, N2 and EW of Balmer and Paschen lines converge toward suggesting an evolutionary sequence of merger stages: all of these quantities are likely to be good time-tracers of the merger phenomenon, and their large spanned range appears to be characteristic of the different merger phases. Half of our sample at higher obscurations have radio sizes approximately 3 times smaller than early type galaxies at the same redshift, suggesting that, in analogy with local ultraluminous infrared galaxies (ULIRGs), these cores cannot be directly forming elliptical galaxies. Finally, we detect mid-IR AGN torus for half of our sample and additional X-ray emission for 6 starbursts; intriguingly, the latter have systematically more compact sizes, suggestive of emerging AGNs toward later merger stages, possibly precursors of a later QSO phase.

AB - Based on optical and near-IR Magellan FIRE spectra of 25 starburst galaxies at 0.5 < z< 0.9, a recent publication showed that their attenuation properties can be explained by a single-parameter sequence of total obscurations ranging from A V = 2 to A V = 30 toward the starburst core centers in a mixed stars and dust configuration. We investigate here the origin of this sequence for the same sample. We show that total attenuations anticorrelate with the starburst sizes in radio (3 GHz) with a significance larger than 5σ and a scatter of 0.26 dex. More obscured and compact starbursts also show enhanced N2 (=[NII]/Hα) ratios and larger line velocity widths that we attribute to an increasing shock contribution toward later merger phases, driven by deeper gravitational potential wells at the coalescence. Additionally, the attenuation is also linked to the equivalent width (EW) of hydrogen recombination lines, which is sensitive to the luminosity weighted age of the relatively unobscured stellar populations. Overall, the correlations among A V, tot , radio size, line width, N2 and EW of Balmer and Paschen lines converge toward suggesting an evolutionary sequence of merger stages: all of these quantities are likely to be good time-tracers of the merger phenomenon, and their large spanned range appears to be characteristic of the different merger phases. Half of our sample at higher obscurations have radio sizes approximately 3 times smaller than early type galaxies at the same redshift, suggesting that, in analogy with local ultraluminous infrared galaxies (ULIRGs), these cores cannot be directly forming elliptical galaxies. Finally, we detect mid-IR AGN torus for half of our sample and additional X-ray emission for 6 starbursts; intriguingly, the latter have systematically more compact sizes, suggestive of emerging AGNs toward later merger stages, possibly precursors of a later QSO phase.

KW - Galaxies: evolution

KW - Galaxies: formation

KW - Galaxies: high-redshift

KW - Galaxies: interactions

KW - Galaxies: star formation

KW - Galaxies: starburst

U2 - 10.1051/0004-6361/201834522

DO - 10.1051/0004-6361/201834522

M3 - Journal article

VL - 623

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A64

ER -