Browsing by Author "Espada, Daniel"

Now showing 1 - 7 of 7
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    A variable active galactic nucleus at z=2.06 triply-imaged by the galaxy cluster MACS J0035.4-2015
    (2023) Furtak, Lukas J.; Mainali, Ramesh; Zitrin, Adi; Plat, Adele; Fujimoto, Seiji; Donahue, Megan; Nelson, Erica J.; Bauer, Franz E.; Uematsu, Ryosuke; Caminha, Gabriel B.; Andrade-Santos, Felipe; Bradley, Larry D.; Caputi, Karina, I; Charlot, Stephane; Chevallard, Jacopo; Coe, Dan; Curtis-Lake, Emma; Espada, Daniel; Frye, Brenda L.; Knudsen, Kirsten K.; Koekemoer, Anton M.; Kohno, Kotaro; Kokorev, Vasily; Laporte, Nicolas; Lee, Minju M.; Lemaux, Brian C.; Magdis, Georgios E.; Sharon, Keren; Stark, Daniel P.; Su, Yuanyuan; Suess, Katherine A.; Ueda, Yoshihiro; Umehata, Hideki; Vidal-Garcia, Alba; Wu, John F.
    We report the discovery of a triply imaged active galactic nucleus (AGN), lensed by the galaxy cluster MACS J0035.4-2015 (z(d) = 0.352). The object is detected in Hubble Space Telescope imaging taken for the RELICS program. It appears to have a quasi-stellar nucleus consistent with a point-source, with a de-magnified radius of r(e) less than or similar to 100 pc. The object is spectroscopically confirmed to be an AGN at z spec = 2.063 +/- 0.005 showing broad rest-frame UV emission lines, and detected in both X-ray observations with Chandra and in ALCS ALMA band 6 (1.2 mm) imaging. It has a relatively faint rest-frame UV luminosity for a quasar-like object, M (UV, 1450) = -19.7 +/- 0.2. The object adds to just a few quasars or other X-ray sources known to be multiply lensed by a galaxy cluster. Some diffuse emission from the host galaxy is faintly seen around the nucleus, and there is a faint object nearby sharing the same multiple-imaging symmetry and geometric redshift, possibly an interacting galaxy or a star-forming knot in the host. We present an accompanying lens model, calculate the magnifications and time delays, and infer the physical properties of the source. We find the rest-frame UV continuum and emission lines to be dominated by the AGN, and the optical emission to be dominated by the host galaxy of modest stellar mass M-* similar or equal to 10(9.2) M-circle dot. We also observe some variation in the AGN emission with time, which may suggest that the AGN used to be more active. This object adds a low-redshift counterpart to several relatively faint AGN recently uncovered at high redshifts with HST and JWST.
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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: average dust, gas, and star-formation properties of cluster and field galaxies from stacking analysis
    (2023) Guerrero, Andrea; Nagar, Neil; Kohno, Kotaro; Fujimoto, Seiji; Kokorev, Vasily; Brammer, Gabriel; Jolly, Jean-Baptiste; Knudsen, Kirsten; Sun, Fengwu; Bauer, Franz E.; Caminha, Gabriel B.; Caputi, Karina; Neumann, Gerald; Orellana-Gonzalez, Gustavo; Cerulo, Pierluigi; Gonzalez-Lopez, Jorge; Laporte, Nicolas; Koekemoer, Anton M.; Ao, Yiping; Espada, Daniel; Arancibia, Alejandra M. Munoz
    We develop new tools for continuum and spectral stacking of Atacama Large Millimeter/submillimeter Array (ALMA) data, and apply these to the ALMA Lensing Cluster Survey. We derive average dust masses, gas masses, and star-formation rates (SFRs) from the stacked observed 260-GHz continuum of 3402 individually undetected star-forming galaxies, of which 1450 are cluster galaxies and 1952 field galaxies, over three redshift and stellar mass bins (over z = 0-1.6 and log M-*[M-circle dot] = 8-11.7), and derive the average molecular gas content by stacking the emission line spectra in a SFR-selected subsample. The average SFRs and specific SFRs of both cluster and field galaxies are lower than those expected for main-sequence (MS) star-forming galaxies, and only galaxies with stellar mass of log M-*[M-circle dot] = 9.35-10.6 show dust and gas fractions comparable with those in the MS. The ALMA-traced average 'highly obscured' SFRs are typically lower than the SFRs observed from optical to near-infrared spectral analysis. Cluster and field galaxies show similar trends in their contents of dust and gas, even when field galaxies were brighter in the stacked maps. From spectral stacking we find a potential CO (J = 4 -> 3) line emission (signal-to-noise ratio being similar to 4) when stacking cluster and field galaxies with the highest SFRs.
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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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    ALMA Lensing Cluster Survey: Full Spectral Energy Distribution Analysis of z ∼ 0.5-6 Lensed Galaxies Detected with millimeter Observations
    (2024) Uematsu, Ryosuke; Ueda, Yoshihiro; Kohno, Kotaro; Toba, Yoshiki; Yamada, Satoshi; Smail, Ian; Umehata, Hideki; Fujimoto, Seiji; Hatsukade, Bunyo; Ao, Yiping; Bauer, Franz Erik; Brammer, Gabriel; Dessauges-Zavadsky, Miroslava; Espada, Daniel; Jolly, Jean-Baptiste; Koekemoer, Anton M.; Kokorev, Vasily; Magdis, Georgios E.; Oguri, Masamune; Sun, Fengwu
    Sub/millimeter galaxies are a key population for the study of galaxy evolution because the majority of star formation at high redshifts occurred in galaxies deeply embedded in dust. To search for this population, we have performed an extensive survey with Atacama Large Millimeter/submillimeter Array (ALMA), called the ALMA Lensing Cluster Survey (ALCS). This survey covers 133 arcmin(2) area and securely detects 180 sources at z similar to 0.5-6 with a flux limit of similar to 0.2 mJy at 1.2 mm. Here, we report the results of multiwavelength spectral energy distribution analysis of the whole ALCS sample, utilizing the observed-frame UV to millimeter photometry. We find that the majority of the ALCS sources lie on the star-forming main sequence, with a smaller fraction showing intense starburst activities. The ALCS sample contains high infrared-excess sources ( IRX = log ( L dust / L UV ) > 1 ), including two extremely dust-obscured galaxies (IRX > 5). We also confirm that the ALCS sample probes a broader range in lower dust mass than conventional submillimeter galaxy samples in the same redshift range. We identify six heavily obscured active galactic nucleus (AGN) candidates that are not detected in the archival Chandra data in addition to the three X-ray AGNs reported by Uematsu et al. (2023). The inferred AGN luminosity density shows a possible excess at z = 2-3 compared with that determined from X-ray surveys below 10 keV.
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    The CAVITY project: The spatially resolved stellar population properties of galaxies in voids
    (2024) Conrado, Ana M.; Delgado, Rosa M. Gonzalez; Garcia-Benito, Ruben; Perez, Isabel; Verley, Simon; Ruiz-Lara, Tomas; Sanchez-Menguiano, Laura; Puertas, Salvador Duarte; Jimenez, Andoni; Dominguez-Gomez, Jesus; Espada, Daniel; Argudo-Fernandez, Maria; Alcazar-Laynez, Manuel; Blazquez-Calero, Guillermo; Bidaran, Bahar; Zurita, Almudena; Peletier, Reynier; Torres-Rios, Gloria; Florido, Estrella; Rodriguez Martinez, Monica; del Moral-Castro, Ignacio; van de Weygaert, Rien; Falcon-Barroso, Jesus; Lugo-Aranda, Alejandra Z.; Sanchez, Sebastian F.; van der Hulst, Thijs; Courtois, Helene M.; Ferre-Mateu, Anna; Sanchez-Blazquez, Patricia; Roman, Javier; Aceituno, Jesus
    The Universe is shaped as a web-like structure, formed by clusters, filaments, and walls that leave large low number-density volumes in between named voids. Galaxies in voids have been found to be of a later type, bluer, less massive, and to have a slower evolution than galaxies in denser environments (filaments and walls). However, the effect of the void environment on their stellar population properties is still unclear. We aim to address this question using 118 optical integral field unit datacubes from the Calar Alto Void Integral-field Treasury surveY (CAVITY), observed with the PMAS/PPaK spectrograph at the 3.5 m telescope at the Calar Alto Observatory (Almer & iacute;a, Spain). We fitted their spectra from 3750 & Aring; to 7000 & Aring; with the non-parametric full spectral fitting code STARLIGHT to estimate their stellar population properties: stellar mass, stellar mass surface density, age, star formation rate (SFR), and specific star formation rate (sSFR). We analysed the results through the global properties, assessing the behaviour of the whole galaxy, and the spatially resolved information, by obtaining the radial profiles from the 2D maps up to the 2 half-light radius of each stellar population property. The results were examined with respect to their morphological type and stellar mass. Then, we compared them with a control sample of galaxies in filaments and walls, selected from the CALIFA survey and analysed following the same procedure. To make a fair comparison between the samples, we selected a twin filament galaxy for each void galaxy of the same morphological type and closest stellar mass, to match the void galaxy sample as much as possible in morphology and mass. Key findings from our global and spatially resolved analysis include void galaxies having a slightly higher half-light radius (HLR), lower stellar mass surface density, and younger ages across all morphological types, and slightly elevated SFR and sSFR (only significant enough for Sas). Many of these differences appear in the outer parts of spiral galaxies (HLR > 1), where discs are younger and exhibit a higher sSFR compared to galaxies in filaments and walls, indicative of less evolved discs. This trend is also found for early-type spirals, suggesting a slower transition from star-forming to quiescent states in voids. Our analysis indicates that void galaxies, influenced by their surroundings, undergo a more gradual evolution, especially in their outer regions, with a more pronounced effect for low-mass galaxies. We find that below a certain mass threshold, environmental processes play a more influential role in galactic evolution.