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The hidden HI-massive LIRG HIZOA J0836-43: Inside-out galaxy formation

  • Cluver, M. E.
  • Jarrett, T. H.
  • Appleton, P. N.
  • Kraan-Korteweg, R. C.
  • Woudt, P. A.
  • Koribalski, B. S.
  • Donley, J. L.
  • Wakamatsu, K.
  • Nagayama, T.
Publication Date
Aug 29, 2008
Submission Date
Aug 29, 2008
DOI: 10.1086/592784
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HIZOA J0836-43 is an extreme gas-rich ($M_{\rm{HI}}$=7.5$\times10^{10} M_{\sun}$) disk galaxy which lies hidden behind the strongly obscuring Vela region of the Milky Way. Utilizing observations from the {\it Spitzer Space Telescope}, we have found it to be a luminous infrared starburst galaxy with a star formation rate of $\sim 21 M_{\sun} \rm{yr^{-1}}$, arising from exceptionally strong molecular PAH emission ($L_{7.7\micron} = 1.50 \times 10^{9} L_{\odot}$) and far-infrared emission from cold dust. The galaxy exhibits a weak mid-infrared continuum compared to other starforming galaxies and U/LIRGs. This relative lack of emission from small grains suggests atypical interstellar medium conditions compared to other starbursts. We do not detect significant $[$Ne {\sc v}$]$ or $[$O {\sc iv}$]$, which implies an absent or very weak AGN. The galaxy possesses a prominent bulge of evolved stars and a stellar mass of 4.4($\pm$1.4)$\times10^{10} M_{\sun}$. With its plentiful gas supply and current star formation rate, a doubling of stellar mass would occur on a timescale of $\sim$2 Gyr. Compared to local galaxies, HIZOA J0836-43 appears to be a "scaled-up" spiral undergoing inside-out formation, possibly resembling stellar disk building processes at intermediate redshifts.


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