Browsing by Author "Bournaud, F."

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    GOODS-ALMA 2.0: Source catalog, number counts, and prevailing compact sizes in 1.1 mm galaxies
    (2022) Gómez-Guijarro, C.; Elbaz, D.; Xiao, M.; Béthermin, M.; Franco, M.; Magnelli, B.; Daddi, E.; Dickinson, M.; Demarco, R.; Inami, H.; Rujopakarn, W.; Magdis, G. E.; Shu, X.; Chary, R.; Zhou, L.; Alexander, D. M.; Bournaud, F.; Ciesla, L.; Ferguson, H. C.; Finkelstein, S. L.; Giavalisco, M.; Iono, D.; Juneau, S.; Kartaltepe, J. S.; Lagache, G.; Le Floc'h, E.; Leiton, R.; Lin, L.; Motohara, K.; Mullaney, J.; Okumura, K.; Pannella, M.; Papovich, C.; Pope, A.; Sargent, M. T.; Silverman, J. D.; Treister, E.; Wang, T.
    Submillimeter/millimeter observations of dusty star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA) have shown that dust continuum emission generally occurs in compact regions smaller than the stellar distribution. However, it remains to be understood how systematic these findings are. Studies often lack homogeneity in the sample selection, target discontinuous areas with inhomogeneous sensitivities, and suffer from modest uv coverage coming from single array configurations. GOODS-ALMA is a 1.1 mm galaxy survey over a continuous area of 72.42 arcmin(2) at a homogeneous sensitivity. In this version 2.0, we present a new low resolution dataset and its combination with the previous high resolution dataset from the survey, improving the uv coverage and sensitivity reaching an average of sigma = 68.4 mu Jy beam(-1). A total of 88 galaxies are detected in a blind search (compared to 35 in the high resolution dataset alone), 50% at S/N-peak >= 5 and 50% at 3.5 <= S/N-peak <= 5 aided by priors. Among them, 13 out of the 88 are optically dark or faint sources (H- or K-band dropouts). The sample dust continuum sizes at 1.1 mm are generally compact, with a median effective radius of R-e = 0 ''.10 +/- 0 ''.5 (a physical size of R-e = 0.73 +/- 0.29 kpc at the redshift of each source). Dust continuum sizes evolve with redshift and stellar mass resembling the trends of the stellar sizes measured at optical wavelengths, albeit a lower normalization compared to those of late-type galaxies. We conclude that for sources with flux densities S-1.1mm > 1 mJy, compact dust continuum emission at 1.1 mm prevails, and sizes as extended as typical star-forming stellar disks are rare. The S-1.1mm < 1 mJy sources appear slightly more extended at 1.1 mm, although they are still generally compact below the sizes of typical star-forming stellar disks.
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    GOODS-ALMA 2.0: Starbursts in the main sequence reveal compact star formation regulating galaxy evolution prequenching
    (2022) Gomez-Guijarro, C.; Elbaz, D.; Xiao, M.; Kokorev, V., I; Magdis, G. E.; Magnelli, B.; Daddi, E.; Valentino, F.; Sargent, M. T.; Dickinson, M.; Bethermin, M.; Franco, M.; Pope, A.; Kalita, B. S.; Ciesla, L.; Demarco, R.; Inami, H.; Rujopakarn, W.; Shu, X.; Wang, T.; Zhou, L.; Alexander, D. M.; Bournaud, F.; Chary, R.; Ferguson, H. C.; Finkelstein, S. L.; Giavalisco, M.; Iono, D.; Juneau, S.; Kartaltepe, J. S.; Lagache, G.; Le Floc'h, E.; Leiton, R.; Leroy, L.; Lin, L.; Motohara, K.; Mullaney, J.; Okumura, K.; Pannella, M.; Papovich, C.; Treister, E.
    Compact star formation appears to be generally common in dusty star-forming galaxies (SFGs). However, its role in the framework set by the scaling relations in galaxy evolution remains to be understood. In this work we follow up on the galaxy sample from the GOODS-ALMA 2.0 survey, an ALMA blind survey at 1.1 mm covering a continuous area of 72.42 arcmin(2) using two array configurations. We derived physical properties, such as star formation rates, gas fractions, depletion timescales, and dust temperatures for the galaxy sample built from the survey. There exists a subset of galaxies that exhibit starburst-like short depletion timescales, but they are located within the scatter of the so-called main sequence of SFGs. These are dubbed starbursts in the main sequence and display the most compact star formation and they are characterized by the shortest depletion timescales, lowest gas fractions, and highest dust temperatures of the galaxy sample, compared to typical SFGs at the same stellar mass and redshift. They are also very massive, accounting for similar to 60% of the most massive galaxies in the sample (log(M-*/M-circle dot) > 11.0). We find trends between the areas of the ongoing star formation regions and the derived physical properties for the sample, unveiling the role of compact star formation as a physical driver of these properties. Starbursts in the main sequence appear to be the extreme cases of these trends. We discuss possible scenarios of galaxy evolution to explain the results drawn from our galaxy sample. Our findings suggest that the star formation rate is sustained in SFGs by gas and star formation compression, keeping them within the main sequence even when their gas fractions are low and they are presumably on the way to quiescence.
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    GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ∼ 3
    (2012) Mullaney, J. R.; Pannella, M.; Daddi, E.; Alexander, D. M.; Elbaz, D.; Hickox, R. C.; Bournaud, F.; Altieri, B.; Aussel, H.; Coia, D.; Dannerbauer, H.; Dasyra, K.; Dickinson, M.; Hwang, H. S.; Kartaltepe, J.; Leiton, R.; Magdis, G.; Magnelli, B.; Popesso, P.; Valtchanov, I.; Bauer, F. E.; Brandt, W. N.; Del Moro, A.; Hanish, D. J.; Ivison, R. J.; Juneau, S.; Luo, B.; Lutz, D.; Sargent, M. T.; Scott, D.; Xue, Y. Q.
    We present a study of the infrared properties of X-ray selected, moderate-luminosity (i.e. L-X = 10(42)-10(44) erg s(-1)) active galactic nuclei (AGNs) up to z approximate to 3, in order to explore the links between star formation in galaxies and accretion on to their central black holes. We use 100 and 160 mu m fluxes from GOODS-Herschel - the deepest survey yet undertaken by the Herschel telescope - and show that in the vast majority of cases (i.e. > 94 per cent) these fluxes are dominated by emission from the host galaxy. As such, these far-infrared bands provide an uncontaminated view of star formation in the AGN host galaxies. We find no evidence of any correlation between the X-ray and infrared luminosities of moderate AGNs at any redshift, suggesting that global star formation is decoupled from nuclear (i.e. AGN) activity in these galaxies. On the other hand, we confirm that the star formation rates of AGN hosts increase strongly with redshift, by a factor of 43(-18)(+27) from z < 0.1 to z = 2-3 for AGNs with the same range of X-ray luminosities. This increase is entirely consistent with the factor of 25-50 increase in the specific star formation rates (SSFRs) of normal, star-forming (i.e. main-sequence) galaxies over the same redshift range. Indeed, the average SSFRs of AGN hosts are only marginally (i.e. approximate to 20 per cent) lower than those of main-sequence galaxies at all surveyed redshifts, with this small deficit being due to a fraction of AGNs residing in quiescent (i.e. low SSFR) galaxies. We estimate that 79 +/- 10 per cent of moderate-luminosity AGNs are hosted in main-sequence galaxies, 15 +/- 7 per cent in quiescent galaxies and < 10 per cent in strongly starbursting galaxies. We derive the fractions of all main-sequence galaxies at z < 2 that are experiencing a period of moderate nuclear activity, noting that it is strongly dependent on galaxy stellar mass (M-stars), rising from just a few per cent at M-stars similar to 10(10) M-circle dot to greater than or similar to 20 per cent at M-stars >= 10(11) M-circle dot. Our results indicate that it is galaxy stellar mass that is most important in dictating whether a galaxy hosts a moderate-luminosity AGN. We argue that the majority of moderate nuclear activity is fuelled by internal mechanisms rather than violent mergers, which suggests that high-redshift disc instabilities could be an important AGN feeding mechanism.
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    The hidden side of cosmic star formation at z > 3 Bridging optically dark and Lyman-break galaxies with GOODS-ALMA
    (Wiley, 2023) Xiao, M-Y.; Elbaz, D.; Gomez-Guijarro, C.; Leroy, L.; Bing, L-J.; Daddi, E.; Magnelli, B.; Franco, M.; Zhou, L.; Dickinson, M.; Wang, T.; Rujopakarn, W.; Magdis, G. E.; Treister, Ezequiel; Inami, H.; Demarco, R.; Sargent, M. T.; Shu, X.; Kartaltepe, J. S.; Alexander, D. M.; Bethermin, M.; Bournaud, F.; Ciesla, L.; Ferguson, H. C.; Finkelstein, S. L.; Giavalisco, M.; Gu, Q-S.; Iono, D.; Juneau, S.; Lagache, G.; Leiton, R.; Messias, H.; Motohara, K.; Mullaney, J.; Nagar, N.; Pannella, M.; Papovich, C.; Pope, A.; Schreiber, C.; Silverman, J.
    Our current understanding of the cosmic star formation history at z > 3 is primarily based on UV-selected galaxies (Lyman-break galaxies, i.e., LBGs). Recent studies of H-dropouts (HST-dark galaxies) have revealed that we may be missing a large proportion of star formation that is taking place in massive galaxies at z > 3. In this work, we extend the H-dropout criterion to lower masses to select optically dark or faint galaxies (OFGs) at high redshifts in order to complete the census between LBGs and H-dropouts. Our criterion (H > 26.5 mag & [4.5] < 25 mag) combined with a de-blending technique is designed to select not only extremely dust-obscured massive galaxies but also normal star-forming galaxies (typically E(B - V) > 0.4) with lower stellar masses at high redshifts. In addition, with this criterion, our sample is not contaminated by massive passive or old galaxies. In total, we identified 27 OFGs at (Zphot) > 3 (with a median of z(med) = 4.1) in the GOODS-ALMA field, covering a wide distribution of stellar masses with log(M-star/M-circle dot) = 9.4-11.1 (with a median of log(M-star med/M-circle dot) = 10.3). We find that up to 75% of the OFGs with log(M-star/M-circle dot) = 9.5-10.5 were neglected by previous LBGs and H-dropout selection techniques. After performing an optical-to-millimeter stacking analysis of the OFGs, we find that rather than being limited to a rare population of extreme starbursts, these OFGs represent a normal population of dusty star-forming galaxies at z > 3. The OFGs exhibit shorter gas depletion timescales, slightly lower gas fractions, and lower dust temperatures than the scaling relation of typical star-forming galaxies. Additionally, the total star formation rate (SFRtot = SFRIR + SFRUV) of the stacked OFGs is much higher than the SFRUVcorr (SFRUV corrected for dust extinction), with an average SFRtot/SFRUVcorr = 8 +/- 1, which lies above (similar to 0.3 dex) the 16-84th percentile range of typical star-forming galaxies at 3 <= z <= 6. All of the above suggests the presence of hidden dust regions in the OFGs that absorb all UV photons, which cannot be reproduced with dust extinction corrections. The effective radius of the average dust size measured by a circular Gaussian model fit in the uv plane is R-e(1.13 mm) = 1.01 +/- 0.05 kpc. After excluding the five LBGs in the OFG sample, we investigated their contributions to the cosmic star formation rate density (SFRD). We found that the SFRD at z > 3 contributed by massive OFGs (log(M-star/M-circle dot) > 10.3) is at least two orders of magnitude higher than the one contributed by equivalently massive LBGs. Finally, we calculated the combined contribution of OFGs and LBGs to the cosmic SFRD at z = 4-5 to be 4 x 10(-2) M-circle dot yr(-1) Mpc(-3), which is about 0.15 dex (43%) higher than the SFRD derived from UV-selected samples alone at the same redshift. This value could be even larger, as our calculations were performed in a very conservative way.
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    The hidden side of cosmic star formation at z > 3 Bridging optically dark and Lyman-break galaxies with GOODS-ALMA
    (2023) Xiao, M-Y.; Elbaz, D.; Gomez-Guijarro, C.; Leroy, L.; Bing, L-J.; Daddi, E.; Magnelli, B.; Franco, M.; Zhou, L.; Dickinson, M.; Wang, T.; Rujopakarn, W.; Magdis, G. E.; Treister, Ezequiel; Inami, H.; Demarco, R.; Sargent, M. T.; Shu, X.; Kartaltepe, J. S.; Alexander, D. M.; Bethermin, M.; Bournaud, F.; Ciesla, L.; Ferguson, H. C.; Finkelstein, S. L.; Giavalisco, M.; Gu, Q-S.; Iono, D.; Juneau, S.; Lagache, G.; Leiton, R.; Messias, H.; Motohara, K.; Mullaney, J.; Nagar, N.; Pannella, M.; Papovich, C.; Pope, A.; Schreiber, C.; Silverman, J.
    Our current understanding of the cosmic star formation history at z > 3 is primarily based on UV-selected galaxies (Lyman-break galaxies, i.e., LBGs). Recent studies of H-dropouts (HST-dark galaxies) have revealed that we may be missing a large proportion of star formation that is taking place in massive galaxies at z > 3. In this work, we extend the H-dropout criterion to lower masses to select optically dark or faint galaxies (OFGs) at high redshifts in order to complete the census between LBGs and H-dropouts. Our criterion (H > 26.5 mag & [4.5] < 25 mag) combined with a de-blending technique is designed to select not only extremely dust-obscured massive galaxies but also normal star-forming galaxies (typically E(B - V) > 0.4) with lower stellar masses at high redshifts. In addition, with this criterion, our sample is not contaminated by massive passive or old galaxies. In total, we identified 27 OFGs at (Zphot) > 3 (with a median of z(med) = 4.1) in the GOODS-ALMA field, covering a wide distribution of stellar masses with log(M-star/M-circle dot) = 9.4-11.1 (with a median of log(M-star med/M-circle dot) = 10.3). We find that up to 75% of the OFGs with log(M-star/M-circle dot) = 9.5-10.5 were neglected by previous LBGs and H-dropout selection techniques. After performing an optical-to-millimeter stacking analysis of the OFGs, we find that rather than being limited to a rare population of extreme starbursts, these OFGs represent a normal population of dusty star-forming galaxies at z > 3. The OFGs exhibit shorter gas depletion timescales, slightly lower gas fractions, and lower dust temperatures than the scaling relation of typical star-forming galaxies. Additionally, the total star formation rate (SFRtot = SFRIR + SFRUV) of the stacked OFGs is much higher than the SFRUVcorr (SFRUV corrected for dust extinction), with an average SFRtot/SFRUVcorr = 8 +/- 1, which lies above (similar to 0.3 dex) the 16-84th percentile range of typical star-forming galaxies at 3 <= z <= 6. All of the above suggests the presence of hidden dust regions in the OFGs that absorb all UV photons, which cannot be reproduced with dust extinction corrections. The effective radius of the average dust size measured by a circular Gaussian model fit in the uv plane is R-e(1.13 mm) = 1.01 +/- 0.05 kpc. After excluding the five LBGs in the OFG sample, we investigated their contributions to the cosmic star formation rate density (SFRD). We found that the SFRD at z > 3 contributed by massive OFGs (log(M-star/M-circle dot) > 10.3) is at least two orders of magnitude higher than the one contributed by equivalently massive LBGs. Finally, we calculated the combined contribution of OFGs and LBGs to the cosmic SFRD at z = 4-5 to be 4 x 10(-2) M-circle dot yr(-1) Mpc(-3), which is about 0.15 dex (43%) higher than the SFRD derived from UV-selected samples alone at the same redshift. This value could be even larger, as our calculations were performed in a very conservative way.