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Reliable Dense-Gas Tracers at High Redshift: CN in the z ∼ 4 Quasar APM 08279

R. Soria-Ruiz, S. García-Burillo, A. Usero

Transactions of IAA RAS, issue 41, 111–115 (2017)

Keywords: Galaxies, high-redshift, radio-lines.

Abstract

Molecular lines have been widely used for the study of galaxy formation and evolution at high-redshift. Of special interest is how the relation between the star formation rate and the dense-gas content varies with redshift. Fair tracers of the dense gas are key to understanding the first phases of galaxy formation. We present for the first time, the detection of the two rotational transitions CN(5–4)@115 GHz and CN(6–5)@138 GHz, in the z ∼ 4 quasar APM 08279 with the IRAM Plateau de Bure interferometer (PdBI). Together with current information on the CN(4–3) line, we have modelled the Spectral Line Energy Distribution (SLED) of CN and derived its molecular abundance in APM 08279. Based on the previous model of the CO molecular emission from APM 08279 we have performed a preliminary analysis of the CN molecular excitation using the radiative transfer code RADEX. To reproduce the observed CN line intensities and the overall SLED, molecular abundances of 5 · 10¯⁸ − 5 · 10¯⁶ are needed. We conclude that the CN emission in APM 08279 is mostly free from IR pumping, and therefore is a fair tracer of the dense-molecular gas at high redshift.

Citation

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RIS

R. Soria-Ruiz, S. García-Burillo, A. Usero. Reliable Dense-Gas Tracers at High Redshift: CN in the z ∼ 4 Quasar APM 08279 // Transactions of IAA RAS. — 2017. — Issue 41. — P. 111–115.

@article{soria-ruiz2017,
  abstract = {Molecular lines have been widely used for the study of galaxy formation and evolution at high-redshift. Of special interest is how the relation between the star formation rate and the dense-gas content varies with redshift. Fair tracers of the dense gas are key to understanding the first phases of galaxy formation. We present for the first time, the detection   of   the   two   rotational   transitions   CN(5–4)@115   GHz   and CN(6–5)@138 GHz, in the z  ∼ 4 quasar APM 08279  with the IRAM
Plateau de Bure interferometer (PdBI). Together with current information on the CN(4–3) line, we have modelled the Spectral Line Energy Distribution (SLED) of CN and derived its molecular abundance in APM 08279. Based on the previous model of the CO molecular emission from APM 08279 we have performed a preliminary analysis of the CN molecular excitation using the radiative transfer  code  RADEX.  To reproduce  the  observed  CN line intensities and the overall SLED, molecular abundances of  5 · 10¯⁸  −  5 · 10¯⁶ are needed. We conclude that the CN emission in APM 08279 is mostly free from IR pumping, and therefore is a fair tracer of the dense-molecular gas at high redshift.},
  author = {R. Soria-Ruiz and S. García-Burillo and A. Usero},
  issue = {41},
  journal = {Transactions of IAA RAS},
  keyword = {Galaxies, high-redshift, radio-lines},
  pages = {111--115},
  title = {Reliable Dense-Gas Tracers at High Redshift: CN in the z ∼ 4 Quasar APM 08279},
  url = {http://iaaras.ru/en/library/paper/1716/},
  year = {2017}
}

TY  - JOUR
TI  - Reliable Dense-Gas Tracers at High Redshift: CN in the z ∼ 4 Quasar APM 08279
AU  - Soria-Ruiz, R.
AU  - García-Burillo, S.
AU  - Usero, A.
PY  - 2017
T2  - Transactions of IAA RAS
IS  - 41
SP  - 111
AB  - Molecular lines have been widely used for the study of galaxy
formation and evolution at high-redshift. Of special interest is how
the relation between the star formation rate and the dense-gas
content varies with redshift. Fair tracers of the dense gas are key
to understanding the first phases of galaxy formation. We present for
the first time, the detection   of   the   two   rotational
transitions   CN(5–4)@115   GHz   and CN(6–5)@138 GHz, in the z  ∼ 4
quasar APM 08279  with the IRAM  Plateau de Bure interferometer
(PdBI). Together with current information on the CN(4–3) line, we
have modelled the Spectral Line Energy Distribution (SLED) of CN and
derived its molecular abundance in APM 08279. Based on the previous
model of the CO molecular emission from APM 08279 we have performed a
preliminary analysis of the CN molecular excitation using the
radiative transfer  code  RADEX.  To reproduce  the  observed  CN
line intensities and the overall SLED, molecular abundances of  5 ·
10¯⁸  −  5 · 10¯⁶ are needed. We conclude that the CN emission in APM
08279 is mostly free from IR pumping, and therefore is a fair tracer
of the dense-molecular gas at high redshift.
UR  - http://iaaras.ru/en/library/paper/1716/
ER  -