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تسجيل مستخدم جديدALMA 1.3 mm Survey of Lensed Submillimeter Galaxies (SMGs) Selected by Herschel: Discovery of Spatially Extended SMGs and Implications
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We present an ALMA 1.3 mm (Band 6) continuum survey of lensed submillimeter galaxies (SMGs) at $z=1.0sim3.2$ with an angular resolution of $sim0.2$. These galaxies were uncovered by the Herschel Lensing Survey (HLS), and feature exceptionally bright far-infrared continuum emission ($S_mathrm{peak} gtrsim 90$ mJy) owing to their lensing magnification. We detect 29 sources in 20 fields of massive galaxy clusters with ALMA. Using both the Spitzer/IRAC (3.6/4.5 $mathrm{mu m}$) and ALMA data, we have successfully modeled the surface brightness profiles of 26 sources in the rest-frame near- and far-infrared. Similar to previous studies, we find the median dust-to-stellar continuum size ratio to be small ($R_mathrm{e,dust}/R_mathrm{e,star} = 0.38pm0.14$) for the observed SMGs, indicating that star formation is centrally concentrated. This is, however, not the case for two spatially extended main-sequence SMGs with a low surface brightness at 1.3 mm ($lesssim 0.1$ mJy arcsec$^{-2}$), in which the star formation is distributed over the entire galaxy ($R_mathrm{e,dust}/R_mathrm{e,star}>1$). As a whole, our SMG sample shows a tight anti-correlation between ($R_mathrm{e,dust}/R_mathrm{e,star}$) and far-infrared surface brightness ($Sigma_mathrm{IR}$) over a factor of $simeq$ 1000 in $Sigma_mathrm{IR}$. This indicates that SMGs with less vigorous star formation (i.e., lower $Sigma_mathrm{IR}$) lack central starburst and are likely to retain a broader spatial distribution of star formation over the whole galaxies (i.e., larger $R_mathrm{e,dust}/R_mathrm{e,star}$). The same trend can be reproduced with cosmological simulations as a result of central starburst and potentially subsequent inside-out quenching, which likely accounts for the emergence of compact quiescent galaxies at $zsim2$.
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