Alma imaging of HCN, CS, and dust in Arp 220 and NGC 6240

Nick Scoville, Kartik Sheth, Fabian Walter, Swarnima Manohar, Laura Zschaechner, Min Yun, Jin Koda, David Sanders, Lena Murchikova, Todd Thompson, Brant E Robertson, Reinhard Genzel, Lars Hernquist, Linda Tacconi, Robert Brown, Desika Narayanan, Christopher C. Hayward, Joshua Barnes, Jeyhan Kartaltepe, Richard Davies & 2 others Paul Van Der Werf, Edward Fomalont

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

We report ALMA Band 7 (350 GHz) imaging at 0.″4-0.″6 resolution and Band 9 (696 GHz) at ∼0.″25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 109 M within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are nH2 ∼ 105 cm-3 at R < 50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with nH2 ∼ 2 × 105 cm-3. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

Original languageEnglish (US)
Article number70
JournalAstrophysical Journal
Volume800
Issue number1
DOIs
StatePublished - Feb 10 2015

Fingerprint

dust
gas
radii
mass media
molecular excitation
emissivity
trapping
gas density
kinematics
gases
wavelength
counters
galaxies
continuums
photons
estimates
wavelengths
excitation
distribution

Keywords

  • Galaxies: individual (Arp 220, NGC 6240)
  • Galaxies: starburst

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Scoville, N., Sheth, K., Walter, F., Manohar, S., Zschaechner, L., Yun, M., ... Fomalont, E. (2015). Alma imaging of HCN, CS, and dust in Arp 220 and NGC 6240. Astrophysical Journal, 800(1), [70]. https://doi.org/10.1088/0004-637X/800/1/70

Alma imaging of HCN, CS, and dust in Arp 220 and NGC 6240. / Scoville, Nick; Sheth, Kartik; Walter, Fabian; Manohar, Swarnima; Zschaechner, Laura; Yun, Min; Koda, Jin; Sanders, David; Murchikova, Lena; Thompson, Todd; Robertson, Brant E; Genzel, Reinhard; Hernquist, Lars; Tacconi, Linda; Brown, Robert; Narayanan, Desika; Hayward, Christopher C.; Barnes, Joshua; Kartaltepe, Jeyhan; Davies, Richard; Van Der Werf, Paul; Fomalont, Edward.

In: Astrophysical Journal, Vol. 800, No. 1, 70, 10.02.2015.

Research output: Contribution to journalArticle

Scoville, N, Sheth, K, Walter, F, Manohar, S, Zschaechner, L, Yun, M, Koda, J, Sanders, D, Murchikova, L, Thompson, T, Robertson, BE, Genzel, R, Hernquist, L, Tacconi, L, Brown, R, Narayanan, D, Hayward, CC, Barnes, J, Kartaltepe, J, Davies, R, Van Der Werf, P & Fomalont, E 2015, 'Alma imaging of HCN, CS, and dust in Arp 220 and NGC 6240', Astrophysical Journal, vol. 800, no. 1, 70. https://doi.org/10.1088/0004-637X/800/1/70
Scoville N, Sheth K, Walter F, Manohar S, Zschaechner L, Yun M et al. Alma imaging of HCN, CS, and dust in Arp 220 and NGC 6240. Astrophysical Journal. 2015 Feb 10;800(1). 70. https://doi.org/10.1088/0004-637X/800/1/70
Scoville, Nick ; Sheth, Kartik ; Walter, Fabian ; Manohar, Swarnima ; Zschaechner, Laura ; Yun, Min ; Koda, Jin ; Sanders, David ; Murchikova, Lena ; Thompson, Todd ; Robertson, Brant E ; Genzel, Reinhard ; Hernquist, Lars ; Tacconi, Linda ; Brown, Robert ; Narayanan, Desika ; Hayward, Christopher C. ; Barnes, Joshua ; Kartaltepe, Jeyhan ; Davies, Richard ; Van Der Werf, Paul ; Fomalont, Edward. / Alma imaging of HCN, CS, and dust in Arp 220 and NGC 6240. In: Astrophysical Journal. 2015 ; Vol. 800, No. 1.
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AU - Scoville, Nick

AU - Sheth, Kartik

AU - Walter, Fabian

AU - Manohar, Swarnima

AU - Zschaechner, Laura

AU - Yun, Min

AU - Koda, Jin

AU - Sanders, David

AU - Murchikova, Lena

AU - Thompson, Todd

AU - Robertson, Brant E

AU - Genzel, Reinhard

AU - Hernquist, Lars

AU - Tacconi, Linda

AU - Brown, Robert

AU - Narayanan, Desika

AU - Hayward, Christopher C.

AU - Barnes, Joshua

AU - Kartaltepe, Jeyhan

AU - Davies, Richard

AU - Van Der Werf, Paul

AU - Fomalont, Edward

PY - 2015/2/10

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N2 - We report ALMA Band 7 (350 GHz) imaging at 0.″4-0.″6 resolution and Band 9 (696 GHz) at ∼0.″25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 109 M⊙ within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are nH2 ∼ 105 cm-3 at R < 50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with nH2 ∼ 2 × 105 cm-3. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

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KW - Galaxies: individual (Arp 220, NGC 6240)

KW - Galaxies: starburst

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