Browsing by Author "Zavala, Jorge A."

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    Characterization of Two 2 mm detected Optically Obscured Dusty Star-forming Galaxies
    (2022) Manning, Sinclaire M.; Casey, Caitlin M.; Zavala, Jorge A.; Magdis, Georgios E.; Drew, Patrick M.; Champagne, Jaclyn B.; Aravena, Manuel; Béthermin, Matthieu; Clements, David L.; Finkelstein, Steven L.; Fujimoto, Seiji; Hayward, Christopher C.; Hodge, Jacqueline A.; Ilbert, Olivier; Kartaltepe, Jeyhan S.; Knudsen, Kirsten K.; Koekemoer, Anton M.; Man, Allison W. S.; Sanders, David B.; Sheth, Kartik; Spilker, Justin S.; Staguhn, Johannes; Talia, Margherita; Treister, Ezequiel; Yun, Min S.
    The 2 mm Mapping Obscuration to Reionization with ALMA (MORA) Survey was designed to detect high-redshift (z greater than or similar to 4), massive, dusty star-forming galaxies (DSFGs). Here we present two likely high-redshift sources, identified in the survey, whose physical characteristics are consistent with a class of optical/near-infrared (OIR)-invisible DSFGs found elsewhere in the literature. We first perform a rigorous analysis of all available photometric data to fit spectral energy distributions and estimate redshifts before deriving physical properties based on our findings. Our results suggest the two galaxies, called MORA-5 and MORA-9, represent two extremes of the "OIR-dark" class of DSFGs. MORA-5 (z(phot) = 4.3(-1.3)(+1.5)) is a significantly more active starburst with a star formation rate (SFR) of 830(-190)(+340) M-circle dot yr(-1) compared to MORA-9 (z(phot) = 4.3(-1.0)(+1.3)), whose SFR is a modest 200(-60)(+250) M-circle dot yr(-1). Based on the stellar masses (M-star approximate to 10(10-11) M-circle dot), space density (n similar to (5 +/- 2) x 10(-6) Mpc(-3), which incorporates two other spectroscopically confirmed OIR-dark DSFGs in the MORA sample at z = 4.6 and z = 5.9), and gas depletion timescales (<1 Gyr) of these sources, we find evidence supporting the theory that OIR-dark DSFGs are the progenitors of recently discovered 3 < z < 4 massive quiescent galaxies.
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    Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies
    (2021) Casey, Caitlin M.; Zavala, Jorge A.; Manning, Sinclaire M.; Aravena, Manuel; Béthermin, Matthieu; Caputi, Karina I.; Champagne, Jaclyn B.; Clements, David L.; Drew, Patrick; Finkelstein, Steven L.; Fujimoto, Seiji; Hayward, Christopher C.; Dekel, Anton M.; Kokorev, Vasily; Lagos, Claudia del P.; Long, Arianna S.; Magdis, Georgios E.; Man, Allison W. S.; Mitsuhashi, Ikki; Popping, Gergö; Spilker, Justin; Staguhn, Johannes; Talia, Margherita; Toft, Sune; Treister, Ezequiel; Weaver, John R.; Yun, Min
    We present the characteristics of 2 mm selected sources from the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey conducted to date, the Mapping Obscuration to Reionization with ALMA (MORA) survey covering 184 arcmin(2) at 2 mm. Twelve of 13 detections above 5 sigma are attributed to emission from galaxies, 11 of which are dominated by cold dust emission. These sources have a median redshift of < Z(2) (mm)> = 3.6(-0.3)(+0.4) primarily based on optical/near-infrared photometric redshifts with some spectroscopic redshifts, with 77% +/- 11% of sources at z > 3 and 38% +/- 12% of sources at z > 4. This implies that 2 mm selection is an efficient method for identifying the highest-redshift dusty star-forming galaxies (DSFGs). Lower-redshift DSFGs (z < 3) are far more numerous than those at z > 3 yet are likely to drop out at 2 mm. MORA shows that DSFGs with star formation rates in excess of 300 M-circle dot yr(-1) and a relative rarity of similar to 10(-5) Mpc(-3) contribute similar to 30% to the integrated star formation rate density at 3 < z < 6. The volume density of 2 mm selected DSFGs is consistent with predictions from some cosmological simulations and is similar to the volume density of their hypothesized descendants: massive, quiescent galaxies at z > 2. Analysis of MORA sources' spectral energy distributions hint at steeper empirically measured dust emissivity indices than reported in typical literature studies, with = 2.2(-0.4)(+0.5). The MORA survey represents an important step in taking census of obscured star formation in the universe's first few billion years, but larger area 2 mm surveys are needed to more fully characterize this rare population and push to the detection of the universe's first dusty galaxies.
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    On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Protoclusters at z ≈ 2.0─2.5
    (2019) Zavala, Jorge A.; Casey, Caitlin M.; Scoville, Nick Z.; Champagne, Jaclyn B.; Chiang, Y.; Dannerbauer, H.; Drew, P.; Fu, Hai; Spilker, J.; Treister, Ezequiel
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    Physical Characterization of an Unlensed, Dusty Star-forming Galaxy at z = 5.85
    (2019) Casey, Caitlin M.; Zavala, Jorge A.; Aravena, Manuel; Bethermin, M.; Caputi, Karina I.; Champagne, Jaclyn B.; Clements, David L.; Cunha, Elisabete da; Drew, Patrick; Treister, Ezequiel
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    SERENADE. II. An ALMA Multiband Dust Continuum Analysis of 28 Galaxies at 5<z<8 and the Physical Origin of the Dust Temperature Evolution
    (2024) Mitsuhashi, Ikki; Harikane, Yuichi; Bauer, Franz E.; Bakx, Tom J. L. C.; Ferrara, Andrea; Fujimoto, Seiji; Hashimoto, Takuya; Inoue, Akio K.; Iwasawa, Kazushi; Nishimura, Yuri; Imanishi, Masatoshi; Ono, Yoshiaki; Saito, Toshiki; Sugahara, Yuma; Umehata, Hideki; Vallini, Livia; Wang, Tao; Zavala, Jorge A.
    We present an analysis of the Atacama Large Millimeter-submillimeter Array (ALMA) multiband dust continuum observations for 28 spectroscopically confirmed bright Lyman break galaxies at 5 < z < 8. Our sample consists of 11 galaxies at z similar to 6 newly observed in our ALMA program, which substantially increases the number of 5 < z < 8 galaxies with both rest-frame 88 and 158 mu m continuum observations, allowing us to simultaneously measure the IR luminosity and dust temperature for a statistical sample of z greater than or similar to 5 galaxies for the first time. We derive the relationship between the ultraviolet (UV) slope (beta(UV)) and infrared excess (IRX) for the z similar to 6 galaxies, and find a shallower IRX-beta(UV) relation compared to the previous results at z similar to 2-4. Based on the IRX-beta(UV) relation consistent with our results and the beta(UV)-M-UV relation including fainter galaxies in the literature, we find a limited contribution of the dust-obscured star formation to the total star formation rate density, similar to 30% at z similar to 6. Our measurements of the dust temperature at z similar to 6-7, T-dust = 40.9(-9.1)(+10.0) K on average, support a gentle increase of T-dust from z = 0 to z similar to 6-7. Using an analytic model with parameters consistent with recent James Webb Space Telescope results, we discuss that the observed redshift evolution of the dust temperature can be reproduced by an similar to 0.6 dex decrease in the gas depletion timescale and similar to 0.4 dex decrease in the metallicity. The variety of T-dust observed at high redshifts can also be naturally explained by scatters around the star formation main sequence and average mass-metallicity relation including an extremely high dust temperature of T-dust > 80 K observed in a galaxy at z = 8.3.