New Identifications and Multi-wavelength Properties of Extragalactic Fermi Gamma-Ray Sources in the SPT-SZ Survey Field. (arXiv:2206.06228v3 [astro-ph.HE] UPDATED)

New Identifications and Multi-wavelength Properties of Extragalactic Fermi Gamma-Ray Sources in the SPT-SZ Survey Field. (arXiv:2206.06228v3 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_L/0/1/0/all/0/1">Lizhong Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vieira_J/0/1/0/all/0/1">Joaquin D. Vieira</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ajello_M/0/1/0/all/0/1">Marco Ajello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Malkan_M/0/1/0/all/0/1">Matthew A. Malkan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Archipley_M/0/1/0/all/0/1">Melanie A. Archipley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Capota_J/0/1/0/all/0/1">Joseph Capota</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Foster_A/0/1/0/all/0/1">Allen Foster</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Madejski_G/0/1/0/all/0/1">Greg Madejski</a>

The fourth Fermi Large Area Telescope (LAT) catalog (4FGL) contains 5064
$gamma$-ray sources detected at high significance, but 26% of them still lack
associations at other wavelengths. The SPT-SZ survey, conducted between 2008
and 2011 with the South Pole Telescope (SPT), covers 2500 $mathrm{deg^2}$ of
the Southern sky in three millimeter-wavelength (mm) bands and was used to
construct a catalog of nearly 5000 emissive sources. In this study, we
introduce a new cross-matching scheme to search for multi-wavelength
counterparts of extragalactic $gamma$-ray sources using a mm catalog. We apply
a Poissonian probability to evaluate the rate of spurious false associations
and compare the multi-wavelength associations from the radio, mm,
near-infrared, and X-ray with 4FGL $gamma$-ray sources. In the SPT-SZ survey
field, 85% of 4FGL sources are associated with mm counterparts. These mm
sources include 94% of previously associated 4FGL sources and 56% of previously
unassociated 4FGL sources. The latter group contains 40 4FGL sources for which
SPT has provided the first identified counterparts. Nearly all of the
SPT-associated 4FGL sources can be described as flat-spectrum radio quasars or
blazars. We find that the mm band is the most efficient wavelength for
detecting $gamma$-ray blazars when considering both completeness and purity.
We also demonstrate that the mm band correlates better to the $gamma$-ray band
than the radio or X-ray bands. With the next generation of CMB experiments,
this technique can be extended to greater sensitivities and more sky area to
further complete the identifications of the remaining unknown $gamma$-ray
blazars.

The fourth Fermi Large Area Telescope (LAT) catalog (4FGL) contains 5064
$gamma$-ray sources detected at high significance, but 26% of them still lack
associations at other wavelengths. The SPT-SZ survey, conducted between 2008
and 2011 with the South Pole Telescope (SPT), covers 2500 $mathrm{deg^2}$ of
the Southern sky in three millimeter-wavelength (mm) bands and was used to
construct a catalog of nearly 5000 emissive sources. In this study, we
introduce a new cross-matching scheme to search for multi-wavelength
counterparts of extragalactic $gamma$-ray sources using a mm catalog. We apply
a Poissonian probability to evaluate the rate of spurious false associations
and compare the multi-wavelength associations from the radio, mm,
near-infrared, and X-ray with 4FGL $gamma$-ray sources. In the SPT-SZ survey
field, 85% of 4FGL sources are associated with mm counterparts. These mm
sources include 94% of previously associated 4FGL sources and 56% of previously
unassociated 4FGL sources. The latter group contains 40 4FGL sources for which
SPT has provided the first identified counterparts. Nearly all of the
SPT-associated 4FGL sources can be described as flat-spectrum radio quasars or
blazars. We find that the mm band is the most efficient wavelength for
detecting $gamma$-ray blazars when considering both completeness and purity.
We also demonstrate that the mm band correlates better to the $gamma$-ray band
than the radio or X-ray bands. With the next generation of CMB experiments,
this technique can be extended to greater sensitivities and more sky area to
further complete the identifications of the remaining unknown $gamma$-ray
blazars.

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