Simulations Find Our Accounting of Dust-Obscured Star Formation May Be Incomplete. (arXiv:1907.03354v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Roebuck_E/0/1/0/all/0/1">Eric Roebuck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sajina_A/0/1/0/all/0/1">Anna Sajina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayward_C/0/1/0/all/0/1">Christopher C. Hayward</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martis_N/0/1/0/all/0/1">Nicholas Martis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marchesini_D/0/1/0/all/0/1">Danilo Marchesini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krefting_N/0/1/0/all/0/1">Nicholas Krefting</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pope_A/0/1/0/all/0/1">Alexandra Pope</a>
The bulk of the star-formation rate density peak at cosmic noon was obscured
by dust. How accurately we can assess the role of dust obscured star-formation
is affected by inherent biases in our empirical methods — both those that rely
on direct dust emission and those that rely on the inferred dust attenuation of
starlight. We use a library of hydrodynamic simulations with radiative transfer
to explore these biases. We find that for IR luminous galaxies that are in
rapidly quenching systems (e.g. post-coalescence) standard luminosity-to-SFR
relations can strongly overestimate the true SFRs. We propose using the
$L_{IR}/L_{1.6}$ color to both help identify such systems and provide more
accurate SFRs. Conversely, we find that the diagnostic UVJ plot misidentifies a
subset of dusty star-forming galaxies. This is due to variability in the
effective attenuation curves including being much grayer in the
optical-to-near-IR regime than the Calzetti starburst law. This is in agreement
with recent observations of IR-selected galaxies at cosmic noon. Our results
support the view that we need a panchromatic approach from the rest-frame UV
through the IR and SED modeling that includes realistic SFHs and allows for
variable attenuation curves if we want to fully account for dust obscured
star-formation across the epochs of greatest galaxy build-up.
The bulk of the star-formation rate density peak at cosmic noon was obscured
by dust. How accurately we can assess the role of dust obscured star-formation
is affected by inherent biases in our empirical methods — both those that rely
on direct dust emission and those that rely on the inferred dust attenuation of
starlight. We use a library of hydrodynamic simulations with radiative transfer
to explore these biases. We find that for IR luminous galaxies that are in
rapidly quenching systems (e.g. post-coalescence) standard luminosity-to-SFR
relations can strongly overestimate the true SFRs. We propose using the
$L_{IR}/L_{1.6}$ color to both help identify such systems and provide more
accurate SFRs. Conversely, we find that the diagnostic UVJ plot misidentifies a
subset of dusty star-forming galaxies. This is due to variability in the
effective attenuation curves including being much grayer in the
optical-to-near-IR regime than the Calzetti starburst law. This is in agreement
with recent observations of IR-selected galaxies at cosmic noon. Our results
support the view that we need a panchromatic approach from the rest-frame UV
through the IR and SED modeling that includes realistic SFHs and allows for
variable attenuation curves if we want to fully account for dust obscured
star-formation across the epochs of greatest galaxy build-up.
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