Rotating Starburst Cores in Massive Galaxies at z = 2.5

Ken-ichi Tadaki, Tadayuki Kodama, Erica J. Nelson, Sirio Belli, Natascha M Förster Schreiber, Reinhard Genzel, Masao Hayashi, Rodrigo Herrera-Camus, Yusei Koyama, Philipp Lang, Dieter Lutz, Rhythm Shimakawa, Linda J. Tacconi, Hannah Ubler, Emily Wisnioski, Stijn Wuyts, Bunyo Hatsukade, Magdalena Lippa, Kouichiro Nakanishi, Soh IkarashiKotaro Kohno, Tomoko L. Suzuki, Yoichi Tamura, Ichi Tanaka

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Abstract

We present spatially resolved ALMA observations of the CO J = 3 - 2 emission line in two massive galaxies at z = 2.5 on the star-forming main sequence. Both galaxies have compact dusty star-forming cores with effective radii of Re = 1.3 ± 0.1 kpc and Re = 1.2 ± 0.1 kpc in the 870 μm continuum emission. The spatial extent of starforming molecular gas is also compact with Re = 1.9 ± 0.4 kpc and Re = 2.3 ± 0.4 kpc, but more extended than the dust emission. Interpreting the observed position-velocity diagrams with dynamical models, we find the starburst cores to be rotation dominated with the ratio of the maximum rotation velocity to the local velocity dispersion of Vmax0 = 7.0+2.5-2.8 (Vmax = 386+36-32 km s-1) and Vmax0 = 4.1+1.7-1.5 (Vmax = 391+54-41 km s-1). Given that the descendants of these massive galaxies in the local universe are likely ellipticals with v/σ nearly an order of magnitude lower, the rapidly rotating galaxies would lose significant net angular momentum in the intervening time. The comparisons among dynamical, stellar, gas, and dust mass suggest that the starburst CO-to-H2 conversion factor of αCO = 0.8 M (K km s-1 pc-2)-1 is appropriate in the spatially resolved cores. The dense cores are likely to be formed in extreme environments similar to the central regions of local ultraluminous infrared galaxies. Our work also demonstrates that a combination of medium-resolution CO and high-resolution dust continuum observations is a powerful tool for characterizing the dynamical state of molecular gas in distant galaxies.

Original languageEnglish
Article numberL25
JournalAstrophysical Journal Letters
Volume841
Issue number2
DOIs
Publication statusPublished - 26 May 2017

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galaxies
dust
gas
molecular gases
angular momentum
continuums
compact galaxies
stars
diagram
stellar mass
universe
diagrams
radii
high resolution
gases
comparison

Keywords

  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Tadaki, K., Kodama, T., Nelson, E. J., Belli, S., Schreiber, N. M. F., Genzel, R., ... Tanaka, I. (2017). Rotating Starburst Cores in Massive Galaxies at z = 2.5. Astrophysical Journal Letters, 841(2), [L25]. https://doi.org/10.3847/2041-8213/aa7338

Rotating Starburst Cores in Massive Galaxies at z = 2.5. / Tadaki, Ken-ichi; Kodama, Tadayuki; Nelson, Erica J.; Belli, Sirio; Schreiber, Natascha M Förster; Genzel, Reinhard; Hayashi, Masao; Herrera-Camus, Rodrigo; Koyama, Yusei; Lang, Philipp; Lutz, Dieter; Shimakawa, Rhythm; Tacconi, Linda J.; Ubler, Hannah; Wisnioski, Emily; Wuyts, Stijn; Hatsukade, Bunyo; Lippa, Magdalena; Nakanishi, Kouichiro; Ikarashi, Soh; Kohno, Kotaro; Suzuki, Tomoko L.; Tamura, Yoichi; Tanaka, Ichi.

In: Astrophysical Journal Letters, Vol. 841, No. 2, L25, 26.05.2017.

Research output: Contribution to journalArticle

Tadaki, K, Kodama, T, Nelson, EJ, Belli, S, Schreiber, NMF, Genzel, R, Hayashi, M, Herrera-Camus, R, Koyama, Y, Lang, P, Lutz, D, Shimakawa, R, Tacconi, LJ, Ubler, H, Wisnioski, E, Wuyts, S, Hatsukade, B, Lippa, M, Nakanishi, K, Ikarashi, S, Kohno, K, Suzuki, TL, Tamura, Y & Tanaka, I 2017, 'Rotating Starburst Cores in Massive Galaxies at z = 2.5', Astrophysical Journal Letters, vol. 841, no. 2, L25. https://doi.org/10.3847/2041-8213/aa7338
Tadaki K, Kodama T, Nelson EJ, Belli S, Schreiber NMF, Genzel R et al. Rotating Starburst Cores in Massive Galaxies at z = 2.5. Astrophysical Journal Letters. 2017 May 26;841(2). L25. https://doi.org/10.3847/2041-8213/aa7338
Tadaki, Ken-ichi ; Kodama, Tadayuki ; Nelson, Erica J. ; Belli, Sirio ; Schreiber, Natascha M Förster ; Genzel, Reinhard ; Hayashi, Masao ; Herrera-Camus, Rodrigo ; Koyama, Yusei ; Lang, Philipp ; Lutz, Dieter ; Shimakawa, Rhythm ; Tacconi, Linda J. ; Ubler, Hannah ; Wisnioski, Emily ; Wuyts, Stijn ; Hatsukade, Bunyo ; Lippa, Magdalena ; Nakanishi, Kouichiro ; Ikarashi, Soh ; Kohno, Kotaro ; Suzuki, Tomoko L. ; Tamura, Yoichi ; Tanaka, Ichi. / Rotating Starburst Cores in Massive Galaxies at z = 2.5. In: Astrophysical Journal Letters. 2017 ; Vol. 841, No. 2.
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abstract = "We present spatially resolved ALMA observations of the CO J = 3 - 2 emission line in two massive galaxies at z = 2.5 on the star-forming main sequence. Both galaxies have compact dusty star-forming cores with effective radii of Re = 1.3 ± 0.1 kpc and Re = 1.2 ± 0.1 kpc in the 870 μm continuum emission. The spatial extent of starforming molecular gas is also compact with Re = 1.9 ± 0.4 kpc and Re = 2.3 ± 0.4 kpc, but more extended than the dust emission. Interpreting the observed position-velocity diagrams with dynamical models, we find the starburst cores to be rotation dominated with the ratio of the maximum rotation velocity to the local velocity dispersion of Vmax/σ0 = 7.0+2.5-2.8 (Vmax = 386+36-32 km s-1) and Vmax/σ0 = 4.1+1.7-1.5 (Vmax = 391+54-41 km s-1). Given that the descendants of these massive galaxies in the local universe are likely ellipticals with v/σ nearly an order of magnitude lower, the rapidly rotating galaxies would lose significant net angular momentum in the intervening time. The comparisons among dynamical, stellar, gas, and dust mass suggest that the starburst CO-to-H2 conversion factor of αCO = 0.8 M⊙ (K km s-1 pc-2)-1 is appropriate in the spatially resolved cores. The dense cores are likely to be formed in extreme environments similar to the central regions of local ultraluminous infrared galaxies. Our work also demonstrates that a combination of medium-resolution CO and high-resolution dust continuum observations is a powerful tool for characterizing the dynamical state of molecular gas in distant galaxies.",
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AU - Belli, Sirio

AU - Schreiber, Natascha M Förster

AU - Genzel, Reinhard

AU - Hayashi, Masao

AU - Herrera-Camus, Rodrigo

AU - Koyama, Yusei

AU - Lang, Philipp

AU - Lutz, Dieter

AU - Shimakawa, Rhythm

AU - Tacconi, Linda J.

AU - Ubler, Hannah

AU - Wisnioski, Emily

AU - Wuyts, Stijn

AU - Hatsukade, Bunyo

AU - Lippa, Magdalena

AU - Nakanishi, Kouichiro

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AB - We present spatially resolved ALMA observations of the CO J = 3 - 2 emission line in two massive galaxies at z = 2.5 on the star-forming main sequence. Both galaxies have compact dusty star-forming cores with effective radii of Re = 1.3 ± 0.1 kpc and Re = 1.2 ± 0.1 kpc in the 870 μm continuum emission. The spatial extent of starforming molecular gas is also compact with Re = 1.9 ± 0.4 kpc and Re = 2.3 ± 0.4 kpc, but more extended than the dust emission. Interpreting the observed position-velocity diagrams with dynamical models, we find the starburst cores to be rotation dominated with the ratio of the maximum rotation velocity to the local velocity dispersion of Vmax/σ0 = 7.0+2.5-2.8 (Vmax = 386+36-32 km s-1) and Vmax/σ0 = 4.1+1.7-1.5 (Vmax = 391+54-41 km s-1). Given that the descendants of these massive galaxies in the local universe are likely ellipticals with v/σ nearly an order of magnitude lower, the rapidly rotating galaxies would lose significant net angular momentum in the intervening time. The comparisons among dynamical, stellar, gas, and dust mass suggest that the starburst CO-to-H2 conversion factor of αCO = 0.8 M⊙ (K km s-1 pc-2)-1 is appropriate in the spatially resolved cores. The dense cores are likely to be formed in extreme environments similar to the central regions of local ultraluminous infrared galaxies. Our work also demonstrates that a combination of medium-resolution CO and high-resolution dust continuum observations is a powerful tool for characterizing the dynamical state of molecular gas in distant galaxies.

KW - galaxies: evolution

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KW - galaxies: ISM

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