A SOFIA Survey of [CII] in the galaxy M51 I. [CII] as a tracer of Star Formation. (arXiv:1811.11769v1 [astro-ph.GA])

A SOFIA Survey of [CII] in the galaxy M51 I. [CII] as a tracer of Star Formation. (arXiv:1811.11769v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pineda_J/0/1/0/all/0/1">Jorge L. Pineda</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Fischer_C/0/1/0/all/0/1">Christian Fischer</a>, (2) <a href="http://arxiv.org/find/astro-ph/1/au:+Kapala_M/0/1/0/all/0/1">Maria Kapala</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Stutzki_J/0/1/0/all/0/1">Juergen Stutzki</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Buchbender_C/0/1/0/all/0/1">Christof Buchbender</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Goldsmith_P/0/1/0/all/0/1">Paul F. Goldsmith</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Ziebart_M/0/1/0/all/0/1">Monika Ziebart</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Glover_S/0/1/0/all/0/1">Simon C. O. Glover</a> (5), <a href="http://arxiv.org/find/astro-ph/1/au:+Klessen_R/0/1/0/all/0/1">Ralf S. Klessen</a> (5), <a href="http://arxiv.org/find/astro-ph/1/au:+Koda_J/0/1/0/all/0/1">Jin Koda</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Kramer_C/0/1/0/all/0/1">Carsten Kramer</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Mookerjea_B/0/1/0/all/0/1">Bhaswati Mookerjea</a> (8), <a href="http://arxiv.org/find/astro-ph/1/au:+Sandstrom_K/0/1/0/all/0/1">Karin Sandstrom</a> (9), <a href="http://arxiv.org/find/astro-ph/1/au:+Scoville_N/0/1/0/all/0/1">Nick Scoville</a> (10), <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_R/0/1/0/all/0/1">Rowan Smith</a> (11), ((1) Jet Propulsion Laboratory, California Institute of Technology,(2) Deutsches SOFIA Institut, (3) University of Cape Town, (4) Universitaet zu Koeln,(5) Universitaet Heidelberg, (6) Stony Brook University, (7) Instituto Radioastronomia Milimetrica (IRAM), (8) Tata Institute of Fundamental Research, (9) University of California, San Diego, (10) California Institute of Technology, (11) University of Manchester)

We present a [CII] 158um map of the entire M51 (including M51b) grand–design
spiral galaxy observed with the FIFI-LS instrument on SOFIA. We compare the
[CII] emission with the total far–infrared (TIR) intensity and star formation
rate(SFR) surface density maps (derived using H_alpha and 24um emission) to
study the relationship between [CII] and the star formation activity in a
variety of environments within M51 on scales of 16″ corresponding to ~660 pc.
We find that [CII] and the SFR surface density are well correlated in the
central, spiral arm, and inter-arm regions. The correlation is in good
agreement with that found for a larger sample of nearby galaxies at kpc scales.
We find that the SFR, and [CII] and TIR luminosities in M51 are dominated by
the extended emission in M51’s disk. The companion galaxy M51b, however, shows
a deficit of [CII] emission compared with the TIR emission and SFR surface
density, with [CII] emission detected only in the S-W part of this galaxy. The
[CII] deficit is associated with an enhanced dust temperature in this galaxy.
We interpret the faint [CII] emission in M51b to be a result of suppressed star
formation in this galaxy, while the bright mid- and far-infrared emission,
which drive the TIR and SFR values, are powered by other mechanisms. A similar
but less pronounced effect is seen at the location of the black hole in M51’s
center. The observed [CII] deficit in M51b suggests that this galaxy is a
valuable laboratory to study the origin of the apparent [CII] deficit observed
in ultra-luminous galaxies.

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