Browsing by Author "Valentino, Francesco"

Now showing 1 - 5 of 5
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    ALMA Lensing Cluster Survey: A spectral stacking analysis of [C II] in lensed z ∼ 6 galaxies
    (2021) Jolly, Jean-Baptiste; Knudsen, Kirsten; Laporte, Nicolas; Richard, Johan; Fujimoto, Seiji; Kohno, Kotaro; Ao, Yiping; Bauer, Franz E.; Egami, Eiichi; Espada, Daniel; Dessauges-Zavadsky, Miroslava; Magdis, Georgios; Schaerer, Daniel; Sun, Fengwu; Valentino, Francesco; Wang, Wei-Hao; Zitrin, Adi
    Context. The properties of galaxies at redshift z>6 hold the key to our understanding of the early stages of galaxy evolution and can potentially identify the sources of the ultraviolet radiation that give rise to the epoch of reionisation. The far-infrared cooling line of [C II] at 158 mu m is known to be bright and correlate with the star formation rate (SFR) of low-redshift galaxies, and hence is also suggested to be an important tracer of star formation and interstellar medium properties for very high-redshift galaxies.
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    ALMA Lensing Cluster Survey: ALMA-Herschel Joint Study of Lensed Dusty Star-forming Galaxies across z ≃ 0.5-6
    (2022) Sun, Fengwu; Egami, Eiichi; Fujimoto, Seiji; Rawle, Timothy; Bauer, Franz E.; Kohno, Kotaro; Smail, Ian; Perez-Gonzalez, Pablo G.; Ao, Yiping; Chapman, Scott C.; Combes, Francoise; Dessauges-Zavadsky, Miroslava; Espada, Daniel; Gonzalez-Lopez, Jorge; Koekemoer, Anton M.; Kokorev, Vasily; Lee, Minju M.; Morokuma-Matsui, Kana; Munoz Arancibia, Alejandra M.; Oguri, Masamune; Pello, Roser; Ueda, Yoshihiro; Uematsu, Ryosuke; Valentino, Francesco; van der Werf, Paul; Walth, Gregory L.; Zemcov, Michael; Zitrin, Adi
    We present an ALMA-Herschel joint analysis of sources detected by the ALMA Lensing Cluster Survey (ALCS) at 1.15 mm. Herschel/PACS and SPIRE data at 100-500 mu m are deblended for 180 ALMA sources in 33 lensing cluster fields that are detected either securely (141 sources; in our main sample) or tentatively at S/N >= 4 with cross-matched HST/Spitzer counterparts, down to a delensed 1.15 mm flux density of similar to 0.02 mJy. We performed far-infrared spectral energy distribution modeling and derived the physical properties of dusty star formation for 125 sources (109 independently) that are detected at >2 sigma in at least one Herschel band. A total of 27 secure ALCS sources are not detected in any Herschel bands, including 17 optical/near-IR-dark sources that likely reside at z = 4.2 +/- 1.2. The 16th, 50th, and 84th percentiles of the redshift distribution are 1.15, 2.08, and 3.59, respectively, for ALCS sources in the main sample, suggesting an increasing fraction of z similar or equal to 1 - 2 galaxies among fainter millimeter sources (f(1150) similar to 0.1 mJy). With a median lensing magnification factor of mu = 2.6(-0.8)(+2.6), ALCS sources in the main sample exhibit a median intrinsic star formation rate of 94(-54)(+84) M-circle dot yr(-1), lower than that of conventional submillimeter galaxies at similar redshifts by a factor of similar to 3. Our study suggests weak or no redshift evolution of dust temperature with L-IR < 10(12) L-circle dot galaxies within our sample at z similar or equal to 0 - 2. At L-IR > 10(12) L-circle dot, the dust temperatures show no evolution across z similar or equal to 1-4 while being lower than those in the local universe. For the highest-redshift source in our sample (z = 6.07), we can rule out an extreme dust temperature (>80 K) that was reported for MACS0416 Y1 at z = 8.31.
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    ALMA Lensing Cluster Survey: Bright [C ii] 158 μm Lines from a Multiply Imaged Sub-L* Galaxy at z=6.0719
    (2021) Fujimoto, Seiji; Oguri, Masamune; Brammer, Gabriel; Yoshimura, Yuki; Laporte, Nicolas; Gonzalez-Lopez, Jorge; Caminha, Gabriel B.; Kohno, Kotaro; Zitrin, Adi; Richard, Johan; Ouchi, Masami; Bauer, Franz E.; Smail, Ian; Hatsukade, Bunyo; Ono, Yoshiaki; Kokorev, Vasily; Umehata, Hideki; Schaerer, Daniel; Knudsen, Kirsten; Sun, Fengwu; Magdis, Georgios; Valentino, Francesco; Ao, Yiping; Toft, Sune; Dessauges-Zavadsky, Miroslava; Shimasaku, Kazuhiro; Caputi, Karina; Kusakabe, Haruka; Morokuma-Matsui, Kana; Shotaro, Kikuchihara; Egami, Eiichi; Lee, Minju M.; Rawle, Timothy; Espada, Daniel
    We present bright [C ii] 158 mu m line detections from a strongly magnified and multiply imaged (mu similar to 20-160) sub-L* (MUV=-19.75-0.44+0.55) Lyman-break galaxy (LBG) at z = 6.0719 +/- 0.0004, drawn from the ALMA Lensing Cluster Survey (ALCS). Emission lines are identified at 268.7 GHz at >= 8 sigma exactly at the positions of two multiple images of the LBG, behind the massive galaxy cluster RXCJ0600-2007. Our lens models, updated with the latest spectroscopy from VLT/MUSE, indicate that a sub region of the LBG crosses the caustic, and is lensed into a long (similar to 6 '') arc with a local magnification of mu similar to 160, for which the [C ii] line is also significantly detected. The source plane reconstruction resolves the interstellar medium (ISM) structure, showing that the [C ii] line is co-spatial with the rest-frame UV continuum at a scale of similar to 300 pc. The [C ii] line properties suggest that the LBG is a rotation-dominated system, whose velocity gradient explains a slight difference in redshifts between the whole LBG and its sub-region. The star formation rate (SFR)-L-[CII] relations, for whole and sub-regions of the LBG, are consistent with those of local galaxies. We evaluate the lower limit of the faint-end of the [C ii] luminosity function at z = 6, finding it to be consistent with predictions from semi-analytical models and from the local SFR-L-[CII] relation with a SFR function at z = 6. These results imply that the local SFR-L-[CII] relation is universal for a wide range of scales, including the spatially resolved ISM, the whole region of the galaxy, and the cosmic scale, even in the epoch of reionization.
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    JWST and ALMA Multiple-line Study in and around a Galaxy at z=8.496: Optical to Far-Infrared Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape
    (2024) Fujimoto, Seiji; Ouchi, Masami; Nakajima, Kimihiko; Harikane, Yuichi; Isobe, Yuki; Brammer, Gabriel; Oguri, Masamune; Gimenez-Arteaga, Clara; Heintz, Kasper E.; Kokorev, Vasily; Bauer, Franz E.; Ferrara, Andrea; Kojima, Takashi; Lagos, Claudia del P.; Laura, Sommovigo; Schaerer, Daniel; Shimasaku, Kazuhiro; Hatsukade, Bunyo; Kohno, Kotaro; Sun, Fengwu; Valentino, Francesco; Watson, Darach; Fudamoto, Yoshinobu; Inoue, Akio K.; Gonzalez-Lopez, Jorge; Koekemoer, Anton M.; Knudsen, Kirsten; Lee, Minju M.; Magdis, Georgios E.; Richard, Johan; Strait, Victoria B.; Sugahara, Yuma; Tamura, Yoichi; Toft, Sune; Umehata, Hideki; Walth, Gregory
    We present Atacama Large Millimeter/submillimeter Array (ALMA) deep spectroscopy for a lensed galaxy at z(spec) = 8.496 with log(M-star/M-circle dot) similar to 7.8 whose optical nebular lines and stellar continuum are detected by JWST/NIRSpec and NIRCam Early Release Observations in the field of SMACS J0723.3-7327. Our ALMA spectrum shows [O III] 88 mu m and [C II] 158 mu m line detections at 4.0 sigma and 4.5 sigma, respectively. The redshift and position of the [O III] line coincide with those of the JWST source, while the [C II] line is blueshifted by 90 km s(-1) with a spatial offset of 0.'' 5 (approximate to 0.5 kpc in the source plane) from the centroid of the JWST source. The NIRCam F444W image, including [O III] lambda 5007 and H beta line emission, spatially extends beyond the stellar components by a factor of >8. This indicates that the z = 8.5 galaxy has already experienced strong outflows as traced by extended [O III] lambda 5007 and offset [C II] emission, which would promote ionizing photon escape and facilitate reionization. With careful slit-loss corrections and the removal of emission spatially outside the galaxy, we evaluate the [O III] 88 mu m/lambda 5007 line ratio, and derive the electron density n (e) by photoionization modeling to be 220(-130)(+230) cm(-3), which is comparable with those of z similar to 2-3 galaxies. We estimate an [O III] 88 mu m/[C II] 158 mu m line ratio in the galaxy of >4, as high as those of known z similar to 6-9 galaxies. This high [O III] 88 mu m/[C II] 158 mu m line ratio is generally explained by the high n(e) as well as the low metallicity (Z(gas)/Z(circle dot)=0.04(-0.02)(+0.02)), high ionization parameter (log U > -2.27), and low carbon-to-oxygen abundance ratio (log(C/O) = [-0.52: -0.24]) obtained from the JWST/NIRSpec data; further [C II] follow-up observations will constrain the covering fraction of photodissociation regions.
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    JWST Insight into a Lensed HST-dark Galaxy and Its Quiescent Companion at z=2.58
    (2023) Kokorev, Vasily; Jin, Shuowen; Magdis, Georgios E.; Caputi, Karina I.; Valentino, Francesco; Dayal, Pratika; Trebitsch, Maxime; Brammer, Gabriel; Fujimoto, Seiji; Bauer, Franz; Iani, Edoardo; Kohno, Kotaro; Sese, David Blanquez; Gomez-Guijarro, Carlos; Rinaldi, Pierluigi; Navarro-Carrera, Rafael
    Using the novel James Webb Space Telescope (JWST)/NIRCam observations in the A2744 field, we present a first spatially resolved overview of a Hubble Space Telescope (HST)-dark galaxy, spectroscopically confirmed at z = 2.58 with magnification mu approximate to 1.9. While being largely invisible at similar to 1 mu m with NIRCam, except for sparse clumpy substructures, the object is well detected and resolved in the long-wavelength bands with a spiral shape clearly visible in F277W. By combining ancillary Atacama Large Millimeter/submillimeter Array (ALMA) and Herschel data, we infer that this object is an edge-on dusty spiral with an intrinsic stellar mass log (M (*)/M (circle dot)) similar to 11.3 and a dust-obscured star formation rate similar to 300 M (circle dot) yr(-1). A massive quiescent galaxy (log (M (*)/M (circle dot)) similar to 10.8) with tidal features lies 2.'' 0 away (r similar to 9 kpc), at a consistent redshift as inferred by JWST photometry, indicating a potential major merger. The dusty spiral lies on the main sequence of star formation, and shows high dust attenuation in the optical (3 < A ( V ) < 4.5). In the far-infrared, its integrated dust spectral energy distribution is optically thick up to lambda (0) similar to 500 mu m, further supporting the extremely dusty nature. Spatially resolved analysis of the HST-dark galaxy reveals a largely uniform A ( V ) similar to 4 area spanning similar to 57 kpc(2), which spatially matches to the ALMA 1 mm continuum emission. Accounting for the surface brightness dimming and the depths of current JWST surveys, unlensed analogs of the HST-dark galaxy at z > 4 would be only detectable in F356W and F444W in an UNCOVER-like survey, and become totally JWST-dark at z similar to 6. This suggests that detecting highly attenuated galaxies in the Epoch of Reionization might be a challenging task for JWST.