916 results on '"Drouart A"'
Search Results
2. COALAS III: The ATCA CO(1-0) look at the growth and death of H$\alpha$ emitters in the Spiderweb protocluster at z=2.16
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Pérez-Martínez, J. M., Dannerbauer, H., Emonts, B. H. C., Allison, J. R., Champagne, J. B., Indermuehle, B., Norris, R. P., Serra, P., Seymour, N., Thomson, A. P., Casey, C. M., Chen, Z., Daikuhara, K., De Breuck, C., D'Eugenio, C., Drouart, G., Hatch, N., Jin, S., Kodama, T., Koyama, Y., Lehnert, M. D., Macgregor, P., Miley, G., Naufal, A., Röttgering, H., Sánchez-Portal, M., Shimakawa, R., Zhang, Y., and Ziegler, B.
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Astrophysics - Astrophysics of Galaxies - Abstract
We obtain CO(1-0) molecular gas measurements with ATCA on a sample of 43 spectroscopically confirmed H$\alpha$ emitters in the Spiderweb protocluster at $z=2.16$ and investigate the relation between their star formation and cold gas reservoirs as a function of environment. We achieve a CO(1-0) detection rate of $\sim23\pm12\%$ with 10 dual CO(1-0) and H$\alpha$ detections at $10<\log M_{*}/M_\odot<11.5$. In addition, we obtain upper limits for the remaining sources. In terms of total gas fractions ($F_{gas}$), our sample is divided into two different regimes with a steep transition at $\log M_{*}/M_\odot\approx10.5$. Galaxies below that threshold have gas fractions that in some cases are close to unity, indicating that their gas reservoir has been replenished by inflows from the cosmic web. However, objects at $\log M_{*}/M_\odot>10.5$ display significantly lower gas fractions and are dominated by AGN (12 out of 20). Stacking results yield $F_{gas}\approx0.55$ for massive emitters excluding AGN, and $F_{gas}\approx0.35$ when examining only AGN candidates. Furthermore, depletion times show that most H$\alpha$ emitters may become passive by $1
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- 2024
3. The GLEAMing of the first supermassive black holes: III. Radio sources with ultra-faint host galaxies
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Broderick, J. W., Seymour, N., Drouart, G., Knight, D., Afonso, J. M., De Breuck, C., Galvin, T. J., Hedge, A. J., Lehnert, M. D., Noirot, G., Shabala, S. S., Turner, R. J., and Vernet, J.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present deep near-infrared $K_{\rm s}$-band imaging for 35 of the 53 sources from the high-redshift ($z > 2$) radio galaxy candidate sample defined in Broderick et al. (2022). These images were obtained using the High-Acuity Widefield $K$-band Imager (HAWK-I) on the Very Large Telescope. Host galaxies are detected for 27 of the sources, with $K_{\rm s} \approx 21.6$$-$$23.0$ mag (2$''$ diameter apertures; AB). The remaining eight targets are not detected to a median $3\sigma$ depth of $K_{\rm s} \approx 23.3$ mag ($2''$ diameter apertures). We examine the radio and near-infrared flux densities of the 35 sources, comparing them to the known $z > 3$ powerful radio galaxies with 500-MHz radio luminosities $L_{500\,{\rm MHz}} > 10^{27}$ W Hz$^{-1}$. By plotting 150-MHz flux density versus $K_{\rm s}$-band flux density, we find that, similar to the sources from the literature, these new targets have large radio to near-infrared flux density ratios, but extending the distribution to fainter flux densities. Five of the eight HAWK-I deep non-detections have a median $3\sigma$ lower limit of $K_{\rm s} \gtrsim 23.8$ mag ($1.5''$ diameter apertures); these five targets, along with a further source from Broderick et al. (2022) with a deep non-detection ($K_{\rm s} \gtrsim 23.7$ mag; $3\sigma$; $2''$ diameter aperture) in the Southern H-ATLAS Regions $K_{\rm s}$-band Survey, are considered candidates to be ultra-high-redshift ($z > 5$) radio galaxies. The extreme radio to near-infrared flux density ratios ($>10^5$) for these six sources are comparable to TN J0924$-$2201, GLEAM J0856$+$0223 and TGSS J1530$+$1049, the three known powerful radio galaxies at $z > 5$. For a selection of galaxy templates with different stellar masses, we show that $z \gtrsim 4.2$ is a plausible scenario for our ultra-high-redshift candidates if the stellar mass $M_{\rm *} \gtrsim 10^{10.5}\,{\rm M}_\odot$. [abridged], Comment: 24 pages, 5 figures (one of which is a multi-page figure with 30 separate panels), 2 tables, accepted for publication in PASA
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- 2024
4. Multi-wavelength properties of three new radio-powerful $z\sim5.6$ quasi-stellar objects discovered from RACS
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Ighina, L., Caccianiga, A., Moretti, A., Broderick, J. W., Leung, J. K., López-Sánchez, A. R., Rigamonti, F., Seymour, N., An, T., Belladitta, S., Bisogni, S., Della Ceca, R., Drouart, G., Gargiulo, A., and Liu, Y.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present a multi-wavelength study of three new $z\sim5.6$ quasi-stellar objects (QSOs) identified from dedicated spectroscopic observations. The three sources were selected as high-$z$ candidates based on their radio and optical/near-infrared properties as reported in the Rapid ASKAP Continuum Survey (RACS), the Dark Energy Survey (DES), and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey. These are among the most radio-bright QSOs currently known at $z>5.5$, relative to their optical luminosity, having $\rm R=S_{\rm 5GHz}/S_{\rm 4400A}>100$. In this work, we present their identification, and we also discuss their multi-wavelength properties (from the radio to the X-ray band) based on detections in public surveys as well as in dedicated radio and X-ray observations. The three sources present a wide range of properties in terms of relative intensity and spectral shape, highlighting the importance of multi-wavelength observations in accurately characterising these high-$z$ objects. In particular, from our analysis we found one source at $z=5.61$ that presents clear blazar properties (strong radio and X-ray emission), making it one of the most distant currently known in this class. Moreover, from the fit of the optical/near-infrared photometric measurements with an accretion disc model as well as the analysis of the CIV broad emission line in one case, we were able to estimate the mass and accretion rate of the central black holes in these systems, finding $\rm M_{\rm BH}\sim1-10\times10^9$~M$_\odot$ accreting at a rate $\lambda_{\rm Edd}\sim0.1-0.4$. The multi-wavelength characterisation of radio QSOs at $z>5.5$, such as the ones reported here, is essential to constraining the evolution of relativistic jets and supermassive black holes hosted in this class of objects., Comment: Accepted for publication on November 4
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- 2024
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5. Comprehensive view on a $z\sim6.5$ radio-loud QSO: from the radio to the optical/NIR to the X-ray band
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Ighina, Luca, Caccianiga, Alessandro, Moretti, Alberto, Broderick, Jess W., Leung, James K., Paterson, Sean, Rigamonti, Fabio, Seymour, Nick, Belladitta, Silvia, Drouart, Guillaume, Galvin, Tim J., and Hurley-Walker, Natasha
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present a multi-wavelength analysis, from the radio to the X-ray band, of the redshift $z=6.44$ VIK J2318$-$31 radio-loud (RL) quasi stellar object (QSO), one of the most distant currently known in this class. The work is based on newly obtained (uGMRT, ATCA, Chandra) as well as archival (GNIRS and X-Shooter) dedicated observations that have not been published yet. Based on the observed X-ray and radio emission, its relativistic jets are likely young and misaligned from our line of sight. Moreover, we can confirm, with simultaneous observations, the presence of a turnover in the radio spectrum at $\nu_{\rm peak} \sim 650$ MHz which is unlikely to be associated with self-synchrotron absorption. From the NIR spectrum we derived the mass of the central black hole, M$_{\rm BH}=8.1^{+6.8}_{-5.6} \times 10^8 {\rm M_{\odot}}$, and the Eddington ratio, $\lambda_{\rm EDD} = 0.8^{+0.8}_{-0.6}$, using broad emission lines as well as an accretion disc model fit to the continuum emission. Given the high accretion rate, the presence of a $\sim$8$\times$10$^8$ M$_\odot$ black hole at $z=6.44$ can be explained by a seed black hole ($\sim$10$^{4}$ M$_\odot$) that formed at $z\sim25$, assuming a radiative efficiency $\eta_{\rm d}\sim0.1$. However, by assuming $\eta_{\rm d}\sim0.3$, as expected for jetted systems, the mass observed would challenge current theoretical models of black hole formation., Comment: Accepted for publication on A&A the 22nd April 2024
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- 2024
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6. COALAS II. Extended molecular gas reservoirs are common in a distant, forming galaxy cluster
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Chen, Zhengyi, Dannerbauer, Helmut, Lehnert, Matthew, Emonts, Bjorn, Gu, Qiusheng, Allison, James R, Champagne, Jaclyn, Hatch, Nina, Indermüehle, Balthasar, Norris, Ray, Pérez-Martínez, José Manuel, Röttgering, Huub, Serra, Paolo, Seymour, Nick, Shimakawa, Rhythm, Thomson, Alasdair, Casey, Caitlin M, De Breuck, Carlos, Drouart, Guillaume, Kodama, Tadayuki, Koyama, Yusei, Urbina, Claudia Lagos, Macgregor, Peter, Miley, George, Rodríguez-Espinosa, José Miguel, Sánchez-Portal, Miguel, and Ziegler, Bodo
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
This paper presents the results of 475 hours of interferometric observations with the Australia Telescope Compact Array towards the Spiderweb protocluster at \(z=2.16\). We search for large, extended molecular gas reservoirs among 46 previously detected CO(1-0) emitters, employing a customised method we developed. Based on the CO emission images and position-velocity diagrams, as well as the ranking of sources using a binary weighting of six different criteria, we have identified 14 robust and 7 tentative candidates that exhibit large extended molecular gas reservoirs. These extended reservoirs are defined as having sizes greater than 40 kpc or super-galactic scale. This result suggests a high frequency of extended gas reservoirs, comprising at least \(30 \%\) of our CO-selected sample. An environmental study of the candidates is carried out based on N-th nearest neighbour and we find that the large molecular gas reservoirs tend to exist in denser regions. The spatial distribution of our candidates is mainly centred on the core region of the Spiderweb protocluster. The performance and adaptability of our method are discussed. We found 13 (potentially) extended gas reservoirs located in nine galaxy (proto)clusters from the literature. We noticed that large extended molecular gas reservoirs surrounding (normal) star-forming galaxies in protoclusters are rare. This may be attributable to the lack of observations low-J CO transitions and the lack of quantitative analyses of molecular gas morphologies. The large gas reservoirs in the Spiderweb protocluster are a potential source of the intracluster medium seen in low redshift Virgo- or Coma-like galaxy clusters., Comment: 25 pages, 16 figures. Accepted for publication in MNRAS
- Published
- 2023
7. 3D tomography of the giant Ly$\alpha$ nebulae of $z$$\approx$3--5 radio-loud AGN
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Wang, Wuji, Wylezalek, Dominika, Vernet, Joël, De Breuck, Carlos, Gullberg, Bitten, Swinbank, Mark, Martín, Montserrat Villar, Lehnert, Matthew, Drouart, Guillaume, Battaia, Fabrizio Arrigoni, Humphrey, Andrew, Noirot, Gaël, Kolwa, Sthabile, Seymour, Nick, and Lagos, Patricio
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Astrophysics - Astrophysics of Galaxies - Abstract
Ly$\alpha$ emission nebulae are ubiquitous around high-z galaxies and are tracers of the gaseous environment on scales out to >100 kpc. High-z radio galaxies (HzRGs, type-2 radio-loud quasars) host large scale nebulae observed in the ionised gas differ from those seen in other types of high-z quasars. In this work, we exploit MUSE observations of Lya nebulae around eight HzRGs ($2.9
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- 2023
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8. The Dragonfly Galaxy. III. Jet-brightening of a High-redshift Radio Source Caught in a Violent Merger of Disk Galaxies
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Lebowitz, Sophie, Emonts, Bjorn, Terndrup, Donald M., Burchett, Joseph N., Prochaska, J. Xavier, Drouart, Guillaume, Villar-Martin, Montserrat, Lehnert, Matthew, De Breuck, Carlos, Vernet, Joel, and Alatalo, Katherine
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The Dragonfly Galaxy (MRC 0152-209), the most infrared-luminous radio galaxy at redshift z~2, is a merger system containing a powerful radio source and large displacements of gas. We present kpc-resolution data from ALMA and the VLA of carbon monoxide (6-5), dust, and synchrotron continuum, combined with Keck integral-field spectroscopy. We find that the Dragonfly consists of two galaxies with rotating disks that are in the early phase of merging. The radio jet originates from the northern galaxy and brightens when it hits the disk of the southern galaxy. The Dragonfly Galaxy therefore likely appears as a powerful radio galaxy because its flux is boosted into the regime of high-z radio galaxies by the jet-disk interaction. We also find a molecular outflow of (1100 $\pm$ 550) M$_{\odot}$/yr associated with the radio host galaxy, but not with the radio hot-spot or southern galaxy, which is the galaxy that hosts the bulk of the star formation. Gravitational effects of the merger drive a slower and longer lived mass displacement at a rate of (170 $\pm$ 40) M$_{\odot}$/yr, but this tidal debris contain at least as much molecular gas mass as the much faster outflow, namely M(H2) = (3 $\pm$ 1) x 10$^9$ (alpha(CO)/0.8) M$_{\odot}$. This suggests that both the AGN-driven outflow and mass transfer due to tidal effects are important in the evolution of the Dragonfly system. The Keck data show Ly$\alpha$ emission spread across 100 kpc, and CIV and HeII emission across 35 kpc, confirming the presence of a metal-rich and extended circumgalactic medium previously detected in CO(1-0)., Comment: Accepted for publication in ApJ (15 pages, 9 figures)
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- 2023
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9. New Radio-Loud QSOs at the end of the Re-ionisation Epoch
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Ighina, L., Caccianiga, A., Moretti, A., Belladitta, S., Broderick, J. W., Drouart, G., Leung, J. K., and Seymour, N.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present the selection of high-redshift ($z\gtrsim5.7$) radio-loud (RL) quasi-stellar object (QSO) candidates from the combination of the radio Rapid ASKAP Continuum Survey (RACS; at 888 MHz) and the optical/near-infrared Dark Energy Survey (DES). In particular, we selected six candidates brighter than $S_{\rm 888MHz}>1$ mJy beam$^{-1}$ and ${\rm mag}(z_\mathrm{{DES}})<21.3$ using the dropout technique (in the $i$-band). From this sample, we were able to confirm the high-$z$ nature ($z\sim6.1$) of two sources, which are now among the highest-redshift RL QSOs currently known. Based on our Gemini-South/GMOS observations, neither object shows a prominent Ly$\alpha$ emission line. This suggests that both sources are likely to be weak emission-line QSOs hosting radio jets and would therefore further strengthen the potential increase of the fraction of weak emission-line QSOs recently found in the literature. However, further multiwavelength observations are needed to constrain the properties of these QSOs and of their relativistic jets. From the discovery of these two sources, we estimated the space density of RL QSOs in the redshift range $5.9
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- 2022
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10. High-resolution laser system for the S3-Low Energy Branch
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Romans, Jekabs, Ajayakumar, Anjali, Authier, Martial, Boumard, Frederic, Caceres, Lucia, Cam, Jean-Francois, Claessens, Arno, Damoy, Samuel, Delahaye, Pierre, Desrues, Philippe, Dong, Wenling, Drouart, Antoine, Duchesne, Patricia, Ferrer, Rafael, Flechard, Xavier, Franchoo, Serge, Gangnant, Patrice, Geldhof, Sarina, de Groote, Ruben P., Lecesne, Nathalie, Leroy, Renan, Lory, Julien, Lutton, Franck, Manea, Vladimir, Merrer, Yvan, Moore, Iain, Ortiz-Cortes, Alejandro, Osmond, Benoit, Piot, Julien, Pochon, Olivier, Raeder, Sebastian, de Roubin, Antoine, Savajols, Herve, Sels, Simon, Studer, Dominik, Traykov, Emil, Uusitalo, Juha, Vandamme, Christophe, Vandebrouck, Marine, Bergh, Paul Van den, Van Duppen, Piet, and Wendt, Klaus
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Nuclear Experiment ,Physics - Atomic Physics - Abstract
In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S$^3$-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S$^3$. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the $4f^{12}6s^2$ $^3H_6 \rightarrow 4f^{12}(^3 H)6s6p$ $J = 5$ atomic transition (415 nm) and the tin isotopes were studied by the $5s^25p^2 (^3P_0) \rightarrow 5s^25p6s (^3P_1)$ atomic transition (286.4 nm), and are used as a benchmark of the laser setup. Additionally, the tin isotopes were studied by the $5s^25p6s (^3P_1) \rightarrow 5s^25p6p (^3P_2)$ atomic transition (811.6 nm), for which new isotope-shift data was obtained and the corresponding field-shift $F_{812}$ and mass-shift $M_{812}$ factors are presented.
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- 2022
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11. The GLEAMing of the first supermassive black holes: II. A new sample of high-redshift radio galaxy candidates
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Broderick, J. W., Drouart, G., Seymour, N., Galvin, T. J., Wright, N., Rosell, A. Carnero, Chhetri, R., Dannerbauer, H., Driver, S. P., Morgan, J. S., Moss, V. A., Prabu, S., Afonso, J. M., De Breuck, C., Emonts, B. H. C., Franzen, T. M. O., Gutiérrez, C. M., Hancock, P. J., Heald, G. H., Hurley-Walker, N., Ivison, R. J., Lehnert, M. D., Noirot, G., Read, M., Shabala, S. S., Stern, D., Sutherland, W. J., Sutorius, E., Turner, R. J., and Vernet, J.
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Astrophysics - Astrophysics of Galaxies - Abstract
While unobscured and radio-quiet active galactic nuclei are regularly being found at redshifts $z > 6$, their obscured and radio-loud counterparts remain elusive. We build upon our successful pilot study, presenting a new sample of low-frequency-selected candidate high-redshift radio galaxies (HzRGs) over a sky area twenty times larger. We have refined our selection technique, in which we select sources with curved radio spectra between 72-231 MHz from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. In combination with the requirements that our GLEAM-selected HzRG candidates have compact radio morphologies and be undetected in near-infrared $K_{\rm s}$-band imaging from the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, we find 51 new candidate HzRGs over a sky area of approximately 1200 deg$^2$. Our sample also includes two sources from the pilot study: the second-most distant radio galaxy currently known, at $z=5.55$, with another source potentially at $z \sim 8$. We present our refined selection technique and analyse the properties of the sample. We model the broadband radio spectra between 74 MHz and 9 GHz by supplementing the GLEAM data with both publicly available data and new observations from the Australia Telescope Compact Array at 5.5 and 9 GHz. In addition, deep $K_{\rm s}$-band imaging from the High-Acuity Widefield $K$-band Imager (HAWK-I) on the Very Large Telescope and from the Southern Herschel Astrophysical Terahertz Large Area Survey Regions $K_{\rm s}$-band Survey (SHARKS) is presented for five sources. We discuss the prospects of finding very distant radio galaxies in our sample, potentially within the epoch of reionisation at $z \gtrsim 6.5$., Comment: 49 pages, 3 figures (one of which is a multi-page figure with 102 separate panels), 9 tables, accepted for publication in PASA
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- 2022
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12. Constraining the Radio Properties of the $z$=6.44 QSO VIK J2318$-$3113
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Ighina, Luca, Leung, James K., Broderick, Jess W., Drouart, Guillaume, Seymour, Nick, Belladitta, Silvia, Caccianiga, Alessandro, Lenc, Emil, Moretti, Alberto, An, Tao, Galvin, Tim J., Heald, George H., Huynh, Minh T., McConnell, David, Murphy, Tara, Pritchard, Joshua, Quici, Benjamin, Shabala, Stas S., Tingay, Steven J., Turner, Ross J., Wang, Yuanming, and White, Sarah V.
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Astrophysics - Astrophysics of Galaxies - Abstract
The recent detection of the quasi-stellar object (QSO) VIKING J231818.3$-$311346 (hereafter VIK J2318$-$3113) at redshift $z=6.44$ in the Rapid ASKAP Continuum Survey (RACS) uncovered its radio-loud nature, making it one of the most distant known to date in this class. By using data from several radio surveys of the Galaxy and Mass Assembly 23$^\mathrm{h}$ field and from dedicated follow-up, we were able to constrain the radio spectrum of VIK J2318$-$3113 in the observed range $\sim$0.1--10 GHz. At high frequencies (0.888--5.5 GHz in the observed frame) the QSO presents a steep spectrum ($\alpha_{\rm r}$=1.24, with $S_\nu\propto \nu^{-\alpha_{\rm r}}$), while at lower frequencies (0.4--0.888 GHz in the observed frame) it is nearly flat. The overall spectrum can be modelled by either a curved function with a rest-frame turnover around 5 GHz, or with a smoothly varying double power law that is flat below a rest-frame break frequency of about 20 GHz and which significantly steepens above it. Based on the model adopted, we estimated that the radio jets of VIK J2318$-$3113 must be a few hundred years old, in the case of a turnover, or less than few$\times$10$^4$ years, in the case of a break in the spectrum. Having multiple observations at two frequencies (888 MHz and 5.5 GHz), we further investigated the radio variability previously reported for this source. We found that the marginally significant flux density variations are consistent with the expectations from refractive interstellar scintillation, even though relativistic effects related to the orientation of the source may still play a non-negligible role. Further radio and X-ray observations are required to conclusively discern the nature of this variation., Comment: Accepted for publication in A&A
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- 2022
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13. HST WFC3/Grism Observations of the Candidate Ultra-High-Redshift Radio Galaxy GLEAM J0917-0012
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Seymour, N., Drouart, G., Noirot, G., Broderick, J. W., Turner, R. J., Shabala, S. S., Stern, D. K., Bellstedt, S., Driver, S., Davies, L., De Breuck, C. A., Afonso, J., Vernet, J. D. R., and Galvin, T. J.
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Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We present Hubble Space Telescope Wide Field Camera 3 photometric and grism observations of the candidate ultra-high-redshift (z>7) radio galaxy, GLEAM J0917-0012. This radio source was selected due to the curvature in its 70-230 MHz, low-frequency Murchison Widefield Array radio spectrum and its faintness in K-band. Follow-up spectroscopic observations of this source with the VLA and ALMA were inconclusive as to its redshift. Our F105W and F0986M imaging observations detect the host of GLEAM J0917-0012 and a companion galaxy, ~one arcsec away. The G102 grism observations reveal a single weak line in each of the spectra of the host and the companion. To help identify these lines we utilised several photometric redshift techniques including template fitting to the grism spectra, fitting the UV-to-radio photometry with galaxy templates plus a synchrotron model, fitting of the UV-to-near-infrared photometry with EAZY, and fitting the radio data alone with RAiSERed. For the host of GLEAM J0917-0012 we find a line at 1.12 micron and the UV-to-radio spectral energy distribution fitting favours solutions at z~2 or z~8. While this fitting shows a weak preference for the lower redshift solution, the models from the higher redshift solution are more consistent with the strength of the spectral line. The redshift constraint by RAiSERed of z>6.5 also supports the interpretation that this line could be Lyman-alpha at z=8.21; however EAZY favours the z~2 solution. We discuss the implications of both solutions. For the companion galaxy we find a line at 0.98 micron and the spectral energy distribution fitting favours solutions at z<3 implying that the line could be the [OII]3727 doublet at z=1.63 (although the EAZY solution is z~2.6+/-0.5). Further observations are still required to unambiguously determine the redshift of this intriguing candidate ultra-high-redshift radio galaxy (abridged)., Comment: 18 pages, 7 figures, 6 tables, accepted for publication in PASA
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- 2022
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14. The COVID-19 Pandemic Highlights International Insecurity and the Violence of Economic Globalisation
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Fontanel, Jacques and Corvaisier-Drouart, Bénédicte
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- 2023
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15. The GLEAMing of the First Supermassive Black Holes
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Drouart, Guillaume, Seymour, Nick, Galvin, Tim J., Afonso, Jose, Callingham, Joseph R., De Breuck, Carlos, Johnston-Hollitt, Melanie, Kapińska, Anna, Lehnert, Matthew D., and Vernet, Joël
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Astrophysics - Astrophysics of Galaxies - Abstract
We present the results of a new selection technique to identify powerful ($L_{\rm 500\,MHz}>10^{27}\,$WHz$^{-1}$) radio galaxies towards the end of the Epoch of Reionisation. Our method is based on the selection of bright radio sources showing radio spectral curvature at the lowest frequency ($\sim 100\,$MHz) combined with the traditional faintness in $K-$band for high redshift galaxies. This technique is only possible thanks to the Galactic and Extra-galactic All-sky Murchison wide-field Array (GLEAM) survey which provides us with 20 flux measurements across the $70-230\,$MHz range. For this pilot project, we focus on the GAMA 09 field to demonstrate our technique. We present the results of our follow-up campaign with the Very Large Telescope, Australian Telescope Compact Array and the Atacama Large Millimetre Array (ALMA) to locate the host galaxy and to determine its redshift. Of our four candidate high redshift sources, we find two powerful radio galaxies in the $1
5.5$ has a high $25-50\%$ success rate., Comment: 19 pages, 9 figures, published in PASA - Published
- 2021
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16. The Nature and Likely Redshift of GLEAM J0917-0012
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Drouart, Guillaume, Seymour, Nick, Broderick, Jess W., Afonso, José, Chhetri, Rajan, De Breuck, Carlos, Emonts, Bjorn, Galvin, Tim J., Lehnert, Matthew D., Morgan, John, Stern, Daniel, Vernet, Joël, and Wright, Nigel
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Astrophysics - Astrophysics of Galaxies - Abstract
We previously reported a putative detection of a radio galaxy at z=10.15, selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The redshift of this source, GLEAM J0917-0012, was based upon three weakly detected molecular emission lines observed with the Atacama Large Millimetre Array (ALMA). In order to confirm this result, we conducted deep spectroscopic follow-up observations with ALMA and the Karl Jansky Very Large Array (VLA). The ALMA observations targeted the same CO lines previously reported in Band 3 (84-115GHz) and the VLA targeted the CO(4-3) and [CI(1-0)] lines for an independent confirmation in Q-band (41 and 44GHz). Neither observation detected any emission lines, removing support for our original interpretation. Adding publicly available optical data from the Hyper Suprime-Cam survey, WISE and Herschel Space Observatory in the infrared, as well as <10GHz polarisation and 162MHz inter-planetary scintillation observations, we model the physical and observational characteristics of GLEAM J0917-0012 as a function of redshift. Comparing these predictions and observational relations to the data, we are able to constrain its nature and distance. We argue that if GLEAM J0917-0012 is at z<3 then it has an extremely unusual nature, and that the more likely solution is that the source lies above z=7., Comment: 19 pages, 6 figures, published in PASA
- Published
- 2021
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17. First observation of high-$K$ isomeric states in $^{249}$Md and $^{251}$Md
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Goigoux, T., Theisen, Ch., Sulignano, B., Airiau, M., Auranen, K., Badran, H., Briselet, R., Calverley, T., Cox, D., Déchery, F., Bisso, F. Defranchi, Drouart, A., Favier, Z., Gall, B., Grahn, T., Greenlees, P. T., Hauschild, K., Herzáň, A., Herzberg, R. -D., Jakobsson, U., Julin, R., Juutinen, S., Konki, J., Leino, M., Lightfoot, A., Lopez-Martens, A., Mistry, A., Nieminen, P., Pakarinen, J., Papadakis, P., Partanen, J., Peura, P., Rahkila, P., Rey-Herme, E., Rubert, J., Ruotsalainen, P., Sandzelius, M., Sarén, J., Scholey, C., Sorri, J., Stolze, S., Uusitalo, J., Vandebrouck, M., Ward, A., Zielińska, M., Jachimowicz, P., Kowal, M., and Skalski, J.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
Decay spectroscopy of the odd-proton nuclei $^{249}$Md and $^{251}$Md has been performed. High-$K$ isomeric states were identified for the first time in these two nuclei through the measurement of their electromagnetic decay. An isomeric state with a half-life of $2.8(5)$ ms and an excitation energy $\geq 910$ keV was found in $^{249}$Md. In $^{251}$Md, an isomeric state with a half-life of $1.4(3)$ s and an excitation energy $\geq 844$ keV was found. Similarly to the neighbouring $^{255}$Lr, these two isomeric states are interpreted as 3 quasi-particle high-$K$ states and compared to new theoretical calculations. Excited nuclear configurations were calculated within two scenarios: via blocking nuclear states located in proximity to the Fermi surface or/and using the quasiparticle Bardeen-Cooper-Schrieffer method. Relevant states were selected on the basis of the microscopic-macroscopic model with a deformed Woods-Saxon potential. The most probable candidates for the configurations of $K$-isomeric states in Md nuclei are proposed.
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- 2021
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18. COALAS: I. ATCA CO(1-0) survey and luminosity function in the Spiderweb protocluster at z=2.16
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Jin, S., Dannerbauer, H., Emonts, B., Serra, P., Lagos, C. D. P., Thomson, A. P., Bassini, L., Lehnert, M., Allison, J. R., Champagne, J. B., Indermuhle, B., Norris, R. P., Seymour, N., Shimakawa, R., Casey, C. M., De Breuck, C., Drouart, G., Hatch, N., Kodama, T., Koyama, Y., Macgregor, P., Miley, G., Overzier, R., Perez-Martinez, J. M., Rodriguez-Espinosa, J. M., Rottgering, H., Portal, M. Sanchez, and Ziegler, B.
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We report a detailed CO(1-0) survey of a galaxy protocluster field at $z=2.16$, based on 475 hours of observations with the Australia Telescope Compact Array. We constructed a large mosaic of 13 individual pointings, covering an area of 21 arcmin$^2$ and $\pm6500$ km/s range in velocity. We obtain a robust sample of 46 CO(1-0) detections spanning $z=2.09-2.22$, constituting the largest sample of molecular gas measurements in protoclusters to date. The CO emitters show an overdensity at $z=2.12-2.21$, suggesting a galaxy super-protocluster or a protocluster connected to large-scale filaments with ~120 cMpc size. We find that 90% CO emitters have distances $>0'.5-4'$ to the center galaxy, indicating that small area surveys would miss the majority of gas reservoirs in similar structures. Half of the CO emitters have velocities larger than escape velocities, which appears gravitationally unbound to the cluster core. These unbound sources are barely found within the $R_{200}$ radius around the center, which is consistent with a picture in which the cluster core is collapsed while outer regions are still in formation. Compared to other protoclusters, this structure contains relatively more CO emitters with relatively narrow line width and high luminosity, indicating galaxy mergers. We use these CO emitters to place the first constraint on the CO luminosity function and molecular gas density in an overdense environment. The amplitude of the CO luminosity function is 1.6$\pm$0.5 orders of magnitudes higher than observed for field galaxy samples at $z\sim2$, and one order of magnitude higher than predictions for galaxy protoclusters from semi-analytical SHARK models. We derive a high molecular gas density of $0.6-1.3\times10^{9}$ $M_\odot$ cMpc$^{-3}$ for this structure, consistent with predictions for cold gas density of massive structures from hydro-dynamical DIANOGA simulations., Comment: 21 pages + Appendices, 9 figures, 6 tables. Accepted for publication in A&A
- Published
- 2021
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19. Radio Detection of VIK J2318$-$3113, the Most Distant Radio-Loud Quasar ($z$=6.44)
- Author
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Ighina, L., Belladitta, S., Caccianiga, A., Broderick, J. W., Drouart, G., Moretti, A., and Seymour, N.
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Astrophysics - Astrophysics of Galaxies - Abstract
We report the 888 MHz radio detection in the Rapid ASKAP Continuum Survey (RACS) of VIK J2318$-$3113, a $z$=6.44 quasar. Its radio luminosity (1.2 $\times 10^{26}$ W Hz$^{-1}$ at 5 GHz) compared to the optical luminosity (1.8 $\times 10^{24}$ W Hz$^{-1}$ at 4400 A) makes it the most distant radio-loud quasar observed so far, with a radio loudness R$\sim$70 (R$=L_\mathrm{{5GHz}}/L_\mathrm{{4400A}}$). Moreover, the high bolometric luminosity of the source (L$_\mathrm{{bol}}$=7.4 $\times 10^{46}$ erg s$^{-1}$) suggests the presence of a supermassive black hole with a high mass ($\gtrsim$6 $\times$10$^8$ M$_\odot$) at a time when the Universe was younger than a billion years. Combining the new radio data from RACS with previous ASKAP observations at the same frequency, we found that the flux density of the source may have varied by a factor of $\sim$2, which could suggest the presence of a relativistic jet oriented towards the line of sight, that is, a blazar nature. However, currently available radio data do not allow us to firmly characterise the orientation of the source. Further radio and X-ray observations are needed., Comment: 5 pages, 2 figures, 3 tables. Accepted for publication in A&A Letters
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- 2021
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20. ALMA detects molecular gas in the halo of the powerful radio galaxy TXS 0828+193
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Fogasy, Judit, Knudsen, Kirsten K., Drouart, Guillaume, and Gullberg, Bitten
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Both theoretical and observational results suggest that high-redshift radio galaxies (HzRGs) inhabit overdense regions of the universe and might be the progenitors of local, massive galaxies residing in the centre of galaxy clusters. In this paper we present CO(3-2) line observations of the HzRG TXS 0828+193 (z=2.57) and its environment using the Atacama Large Millimeter/submillimeter Array. In contrast to previous observations, we detect CO emission associated with the HzRG and derive a molecular gas mass of $(0.9\pm0.3)\times10^{10}\,\rm M_{\odot}$. Moreover, we confirm the presence of a previously detected off-source CO emitting region (companion #1), and detect three new potential companions. The molecular gas mass of each companion is comparable to that of the HzRG. Companion #1 is aligned with the axis of the radio jet and has stellar emission detected by Spitzer. Thus this source might be a normal star-forming galaxy or alternatively a result of jet-induced star formation. The newly found CO sources do not have counterparts in any other observing band and could be high-density clouds in the halo of TXS 0828+193 and thus potentially linked to the large-scale filamentary structure of the cosmic web., Comment: Accepted by MNRAS; 9 pages, 4 figures
- Published
- 2020
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21. RAiSERed: radio continuum redshifts for lobed AGNs
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Turner, Ross J., Drouart, Guillaume, Seymour, Nick, and Shabala, Stanislav S.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Next-generation radio surveys are expected to detect tens of millions of active galactic nuclei (AGN) with a median redshift of z > 1. Beyond targeted surveys, the vast majority of these objects will not have spectroscopic redshifts, whilst photometric redshifts for high-redshift AGNs are of limited quality, and even then require optical and infrared photometry. We propose a new approach to measure the redshifts of lobed radio galaxies based exclusively on radio-frequency imaging and broadband radio photometry. Specifically, our algorithm uses the lobe flux density, angular size and width, and spectral shape to derive probability density functions for the most likely source redshift based on the Radio AGN in Semi-analytic Environments (RAiSE) dynamical model. The full physically based model explains 70% of the variation in the spectroscopic redshifts of a high-redshift (2 < z < 4) sample of radio AGNs, compared to at most 27% for any one of the observed attributes in isolation. We find that upper bounds on the angular size, as expected for unresolved sources, are sufficient to yield accurate redshift measurements at z > 2. The error in the model upon calibration using at least nine sources with known spectroscopic redshifts is <14% in redshift (as 1 + z) across all redshifts. We provide python code for the calculation and calibration of our radio continuum redshifts in an online library., Comment: 14 pages, 9 figures, 4 tables; accepted in MNRAS. Code available at github.com/rossjturner/RAiSERed
- Published
- 2020
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22. SMM J04135+10277: A distant QSO-starburst system caught by ALMA
- Author
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Fogasy, Judit, Knudsen, Kirsten K., Drouart, Guillaume, Lagos, Claudia del P., and Fan, Lulu
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
The gas content of galaxies is a key factor for their growth, starting from star formation and black hole accretion to galaxy mergers. Thus, characterising its properties via observations of tracers like the CO emission line is of big importance in order to understand the bigger picture of galaxy evolution. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of dust continuum, CO(5-4) and CO(8-7) line emission in the quasar--star-forming companion system SMM J04135+10277 (z=2.84). Earlier low-$J$ CO studies of this system found a huge molecular gas reservoir associated to the companion galaxy, while the quasar appeared gas-poor. Our CO observations revealed that the host galaxy of the quasar is also gas-rich, with an estimated molecular gas mass of $\sim(0.7-2.3)\times10^{10}$ M$_{\odot}$. The CO line profiles of the companion galaxy are broad ($\sim1000$ km s$^{-1}$), and show signs of rotation of a compact, massive system. In contrast to previous far-infrared observations, we resolve the continuum emission and detect both sources, with the companion galaxy dominating the dust continuum and the quasar having a $\sim25\%$ contribution to the total dust emission. By fitting the infrared spectral energy distribution of the sources with \textsc{MR-MOOSE} and empirical templates, the infrared luminosities of the quasar and the companion are in the range of $L_{\rm IR, QSO}\sim(2.1-9.6)\times10^{12}$ L$_{\odot}$ and $L_{\rm IR, Comp.}\sim(2.4-24)\times10^{12}$ L$_{\odot}$, while the estimated star formation rates are $\sim210-960$ M$_{\odot}$ yr$^{-1}$ and $\sim240-2400$ M$_{\odot}$ yr$^{-1}$, respectively. Our results demonstrate that non-detection of low-$J$ CO transition lines in similar sources does not necessarily imply the absence of massive molecular gas reservoir but that the excitation conditions favour the excitation of high-$J$ transitions., Comment: Accepted by MNRAS; 14 pages, 9 figures
- Published
- 2020
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23. Lifetime measurements on fission fragments in the A ∼ 100 region
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Grente L., Salsac M.-D., Korten W., Görgen A., Hagen T. W., Braunroth T., Bruyneel B., Celikovic I., Clément E., Delaune O., Dijon A., Drouart A., Ertürk S., Farget F., de France G., Gottardo A., Hackstein M., Jacquot B., Libert J., Litzinger J., Ljungvall J., Louchart C., Michelagnoli C., Napoli D.R., Navin A., Pillet N., Pipidis A., Recchia F., Rejmund M., Rother W., Sahin E., Schmitt C., Siem S., Sulignano B., Valiente-Dobon J.J., and Zell K.O.
- Subjects
Physics ,QC1-999 - Abstract
Lifetimes of first 4+ and 6+ states have been measured in neutron-rich isotopes of Zr, Mo, Ru and Pd using the recoil distance Doppler shift method at GANIL. The nuclei were produced through a fusion-fission reaction in inverse kinematics. The fission fragments were fully identified in the large-acceptance VAMOS spectrometer and γ-rays were detected in coincidence with the EXOGAM germanium array. Lifetimes of excited states in the range of 1–100 ps were measured with the Cologne plunger. Preliminary lifetime results are presented as well as a discussion on the evolution of the collectivity in this region.
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- 2013
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24. Long lifetime components in the decay of excited super-heavy nuclei
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Morjean M., Chbihi A., Dasgupta M., Drouart A., Frankland J.D., Frégeau J.D., Hinde D.J., Jacquet D., Nalpas L., Pârlog M., Simenel C., Tassan-Got L., and Williams E.
- Subjects
Physics ,QC1-999 - Abstract
For nuclear reactions in which super-heavy nuclei can be formed, the essential difference between the fusion process followed by fission and non-equilibrium processes leading to fission-like fragments is there action time. Quite probable non-equilibrium processes, characterized by very short reaction times, are highlighted thanks to mass-angle correlations. However, long lifetime components associated with fission following fusion have been observed with two independent experimental techniques, providing evidence for the formation of compound nuclei with Z = 120 and 124, followed by mass asymmetric fission.
- Published
- 2013
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25. Fusion-evaporation studies with the Super Separator spectrometer (S3) at Spiral2
- Author
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Déchery F., Boutin D., Amthor A. M., Drouart A., Nolen J. A., and Savajols H.
- Subjects
Physics ,QC1-999 - Abstract
The Super Separator Spectrometer S3 is a device designed for experiments with the very high intensity stable ion beam of the superconducting linear accelerator of the SPIRAL2 facility. Its Physics goals cover the study of radioactive ions produced by fusion-evaporation reactions, like superheavy elements or neutron deficient nuclei close to the proton drip line, but also neutron rich nuclei produced by multi-nucleon transfer reactions as well as ion-ion atomic interactions. It is composed of a two-step separator, with a momentum achromat followed by a mass spectrometer. Superconducting multipole triplets, combining quadruple, sextuple and octupole fields, allow a combination of high transmission and mass resolution. A specific open multipole has been designed to stop the high beam power at the first momentum dispersive plane. A decay spectroscopy detection set-up or a low energy branch can be coupled to S3 for a wide range of studies.
- Published
- 2011
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26. In-beam gamma-ray and electron spectroscopy of $^{249,251}$Md
- Author
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Briselet, R., Theisen, Ch., Sulignano, B., Airiau, M., Auranen, K., Cox, D. M., Déchery, F., Drouart, A., Favier, Z., Gall, B., Goigoux, T., Grahn, T., Greenlees, P. T., Hauschild, K., Herzan, A., Herzberg, R. -D., Jakobsson, U., Julin, R., Juutinen, S., Konki, J., Leino, M., Lopez-Martens, A., Mistry, A., Nieminen, P., Pakarinen, J., Papadakis, P., Peura, P., Rahkila, P., Rey-Herme, E., Rubert, J., Ruotsalainen, P., Sandzelius, M., Sarén, J., Scholey, C., Sorri, J., Stolze, S., Uusitalo, J., Vandebrouck, M., Ward, A., Zielińska, M., Bally, B., Bender, M., and Ryssens, W.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
The odd-$Z$ $^{251}$Md nucleus was studied using combined $\gamma$-ray and conversion-electron in-beam spectroscopy. Besides the previously observed rotational band based on the $[521]1/2^-$ configuration, another rotational structure has been identified using $\gamma$-$\gamma$ coincidences. The use of electron spectroscopy allowed the rotational bands to be observed over a larger rotational frequency range. Using the transition intensities that depend on the gyromagnetic factor, a $[514]7/2^-$ single-particle configuration has been inferred for this band, i.e., the ground-state band. A physical background that dominates the electron spectrum with an intensity of $\simeq$ 60% was well reproduced by simulating a set of unresolved excited bands. Moreover, a detailed analysis of the intensity profile as a function of the angular momentum provided a method for deriving the orbital gyromagnetic factor, namely $g_K = 0.69^{+0.19}_{-0.16}$ for the ground-state band. The odd-$Z$ $^{249}$Md was studied using $\gamma$-ray in-beam spectroscopy. Evidence for octupole correlations resulting from the mixing of the $\Delta l = \Delta j = 3$ $[521]3/2^-$ and $[633]7/2^+$ Nilsson orbitals were found in both $^{249,251}$Md. A surprising similarity of the $^{251}$Md ground-state band transition energies with those of the excited band of $^{255}$Lr has been discussed in terms of identical bands. Skyrme-Hartree-Fock-Bogoliubov calculations were performed to investigate the origin of the similarities between these bands.
- Published
- 2020
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27. MUSE unravels the ionisation and origin of metal enriched absorbers in the gas halo of a z = 2.92 radio galaxy
- Author
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Kolwa, S., Vernet, J., De Breuck, C., Villar-Martin, M., Humphrey, A., Arrigoni-Battaia, F., Gullberg, B., Falkendal, T., Drouart, G., Lehnert, M., Wylezalek, D., and Man, A.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We have used the Multi-Unit Spectroscopic Explorer (MUSE) to study the circumgalactic medium (CGM) of a z = 2.92 radio galaxy, MRC 0943-242 by parametrising its emitting and absorbing gas. In both Ly$\alpha$ $\lambda$1216 and He II $\lambda$1640 lines, we observe emission with velocity shifts of $\Delta v \simeq-1000$ km s$^{-1}$ from the systemic redshift of the galaxy. These blueshifted components represent kinematically perturbed gas that is aligned with the radio axis, which we interpret as jet-driven outflows. Three of the four known Ly$\alpha$ absorbers are detected at the same velocity as C IV $\lambda\lambda1548,1551$ and N V $\lambda\lambda1239,1243$ absorbers, proving that the gas is metal enriched more so than previously thought. At the velocity of a strong Ly$\alpha$ absorber with an HI column of $N_{\rm HI}/{\rm cm}^{-2} = 10^{19.2}$ and velocity shift of $\Delta v \simeq -400$ km s$^{-1},$ we also detect Si II $\lambda$1260 and Si II $\lambda$1527 absorption, which suggests that the absorbing gas is ionisation bounded. With the added sensitivity of this MUSE observation, we are more capable of adding constraints to absorber column densities and consequently determining what powers their ionisation. To do this, we obtain photoionisation grid models in \pkg{cloudy} which show that AGN radiation is capable of ionising the gas and producing the observed column densities in a gas of metallicity of Z/Z$_\odot \simeq$ 0.01 with a nitrogen abundance a factor of 10 greater than that of hydrogen. This metal-enriched absorbing gas, which is also spatially extended over a projected distance of $r \gtrsim 60$ kpc, is likely to have undergone chemical enrichment through stellar winds that have swept up metals from the interstellar-medium and deposited them in the outer regions of the galaxy's halo., Comment: 21 pages, 20 figures, accepted for publication in A&A
- Published
- 2019
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28. Nude in an Interior.
- Author
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Drouart, Raphaël and Drouart, Raphaël
- Subjects
- Prints, French 20th century., Women., Estampe française 20e siècle., Femmes., interior architecture (object genre), women (female humans), Prints, French, Women
- Published
- 2024
29. In-gas-jet laser spectroscopy with S[formula omitted]-LEB
- Author
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Ajayakumar, Anjali, Romans, Jekabs, Authier, Martial, Balasmeh, Yazeed, Brizard, Alexandre, Boumard, Frederic, Caceres, Lucia, Cam, Jean-Francois, Claessens, Arno, Damoy, Samuel, Delahaye, Pierre, Desrues, Philippe, Dong, Wenling, Drouart, Antoine, Duchesne, Patricia, Ferrer, Rafael, Fléchard, Xavier, Franchoo, Serge, Gangnant, Patrice, Geldhof, Sarina, de Groote, Ruben P., Ivandikov, Fedor, Lecesne, Nathalie, Leroy, Renan, Lory, Julien, Lutton, Franck, Manea, Vladimir, Merrer, Yvan, Moore, Iain, Ortiz-Cortes, Alejandro, Osmond, Benoit, Piot, Julien, Pochon, Olivier, Raeder, Sebastian, de Roubin, Antoine, Savajols, Hervé, Studer, Dominik, Traykov, Emil, Uusitalo, Juha, Vandamme, Christophe, Van den Bergh, Paul, Van Duppen, Piet, and Wendt, Klaus
- Published
- 2023
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30. Production cross section and decay study of $^{243}$Es and $^{249}$Md
- Author
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Briselet, R., Theisen, Ch., Vandebrouck, M., Marchix, A., Airiau, M., Auranen, K., Badran, H., Boilley, D., Calverley, T., Cox, D., Déchery, F., Bisso, F. Defranchi, Drouart, A., Gall, B., Goigoux, T., Grahn, T., Greenlees, P. T., Hauschild, K., Herzan, A., Herzberg, R. D., Jakobsson, U., Julin, R., Juutinen, S., Konki, J., Leino, M., Lightfoot, A., Lopez-Martens, A., Mistry, A., Nieminen, P., Pakarinen, J., Papadakis, P., Partanen, J., Peura, P., Rahkila, P., Rubert, J., Ruotsalainen, P., Sandzelius, M., Saren, J., Scholey, C., Sorri, J., Stolze, S., Sulignano, B., Uusitalo, J., Ward, A., and Zielińska, M.
- Subjects
Nuclear Experiment - Abstract
In the study of the odd-$Z$, even-$N$ nuclei $^{243}$Es and $^{249}$Md, performed at the University of Jyv\"askyl\"a, the fusion-evaporation reactions $^{197}$Au($^{48}$Ca,2$n$)$^{243}$Es and $^{203}$Tl($^{48}$Ca,2$n$)$^{249}$Md have been used for the first time. Fusion-evaporation residues were selected and detected using the RITU gas-filled separator coupled with the focal-plane spectrometer GREAT. For $^{243}$Es, the recoil decay correlation analysis yielded a half-life of $24 \pm 3$s, and a maximum production cross section of $37 \pm 10$ nb. In the same way, a half-life of $26 \pm 1$ s, an $\alpha$ branching ratio of 75 $\pm$ 5%, and a maximum production cross section of 300 $\pm$ 80 nb were determined for $^{249}$Md. The decay properties of $^{245}$Es, the daughter of $^{249}$Md, were also measured: an $\alpha$ branching ratio of 54 $\pm$ 7% and a half-life of 65 $\pm$ 6 s. Experimental cross sections were compared to the results of calculations performed using the KEWPIE2 statistical fusion-evaporation code.
- Published
- 2018
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31. Massive galaxies on the road to quenching: ALMA observations of powerful high redshift radio galaxies
- Author
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Falkendal, Theresa, De Breuck, Carlos, Lehnert, Matthew D., Drouart, Guillaume, Vernet, Joël, Emonts, Bjorn, Lee, Minju, Nesvadba, Nicole P. H., Seymour, Nick, Béthermin, Matthieu, Kolwa, Sthabile, Gullberg, Bitten, and Wylezalek, Dominika
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We present 0.3" (band 6) and 1.5" (band 3) ALMA observations of the (sub)millimeter dust continuum emission for 25 radio galaxies at 1
- Published
- 2018
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32. Mr-Moose: An advanced SED-fitting tool for heterogeneous multi-wavelength datasets
- Author
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Drouart, Guillaume and Falkendal, Theresa
- Subjects
Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We present the public release of MrMoose, a fitting procedure that is able to perform multi-wavelength and multi-object spectral energy distribution (SED) fitting in a Bayesian framework. This procedure is able to handle a large variety of cases, from an isolated source to blended multi-component sources from an heterogeneous dataset (i.e. a range of observation sensitivities and spectral/spatial resolutions). Furthermore, MrMoose handles upper-limits during the fitting process in a continuous way allowing models to be gradually less probable as upper limits are approached. The aim is to propose a simple-to-use, yet highly-versatile fitting tool fro handling increasing source complexity when combining multi-wavelength datasets with fully customisable filter/model databases. The complete control of the user is one advantage, which avoids the traditional problems related to the "black box" effect, where parameter or model tunings are impossible and can lead to overfitting and/or over-interpretation of the results. Also, while a basic knowledge of Python and statistics is required, the code aims to be sufficiently user-friendly for non-experts. We demonstrate the procedure on three cases: two artificially-generated datasets and a previous result from the literature. In particular, the most complex case (inspired by a real source, combining Herschel, ALMA and VLA data) in the context of extragalactic SED fitting, makes MrMoose a particularly-attractive SED fitting tool when dealing with partially blended sources, without the need for data deconvolution.
- Published
- 2018
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33. ALMA detections of CO emission in the most luminous, heavily dust-obscured quasars at z>3
- Author
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Fan, Lulu, Knudsen, Kirsten K., Fogasy, Judit, and Drouart, Guillaume
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We report the results of a pilot study of CO$(4-3)$ emission line of three {\it WISE}-selected hyper-luminous, dust-obscured quasars (QSOs) with sensitive ALMA Band 3 observations. These obscured QSOs with $L_{\rm bol}>10^{14}L_\odot$ are among the most luminous objects in the universe. All three QSO hosts are clearly detected both in continuum and in CO$(4-3)$ emission line. Based on CO$(4-3)$ emission line detection, we derive the molecular gas masses ($\sim 10^{10-11}$ M$_\odot$), suggesting that these QSOs are gas-rich systems. We find that three obscured QSOs in our sample follow the similar $L'_{\rm CO}- L_{\rm FIR}$ relation as unobscured QSOs at high redshifts. We also find the complex velocity structures of CO$(4-3)$ emission line, which provide the possible evidence for gas-rich merger in W0149+2350 and possible molecular outflow in W0220+0137 and W0410$-$0913. Massive molecular outflow can blow away the obscured interstellar medium (ISM) and make obscured QSOs evolve towards the UV/optical bright, unobscured phase. Our result is consistent with the popular AGN feedback scenario involving the co-evolution between the SMBH and host galaxy., Comment: 3 figures, 2 tables
- Published
- 2017
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34. Evidence for the role of proton shell closure in quasi-fission reactions from X-ray fluorescence of mass-identified fragments
- Author
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Morjean, M., Hinde, D. J., Simenel, C., Jeung, D. Y., Airiau, M., Cook, K. J., Dasgupta, M., Drouart, A., Jacquet, D., Kalkal, S., Palshetkar, C. S., Prasad, E., Rafferty, D., Simpson, E. C., Tassan-Got, L., Vo-Phuoc, K., and Williams, E.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
The atomic numbers and the masses of fragments formed in quasi-fission reactions have been simultaneously measured at scission in 48 Ti + 238 U reactions at a laboratory energy of 286 MeV. The atomic numbers were determined from measured characteristic fluorescence X-rays whereas the masses were obtained from the emission angles and times of flight of the two emerging fragments. For the first time, thanks to this full identification of the quasi-fission fragments on a broad angular range, the important role of the proton shell closure at Z = 82 is evidenced by the associated maximum production yield, a maximum predicted by time dependent Hartree-Fock calculations. This new experimental approach gives now access to precise studies of the time dependence of the N/Z (neutron over proton ratios of the fragments) evolution in quasi-fission reactions., Comment: 6 pages, 5 figures, accepted for publication in Phys.Rev.Lett
- Published
- 2017
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35. Are we seeing accretion flows in a 250kpc-sized Ly-alpha halo at z=3?
- Author
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Vernet, J., Lehnert, M. D., De Breuck, C., Villar-Martin, M., Wylezalek, D., Falkendal, T., Drouart, G., Kolwa, S., Humphrey, A., Venemans, B. P., and Boulanger, F.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Using MUSE on the ESO-VLT, we obtained a 4 hour exposure of the z=3.12 radio galaxy MRC0316-257. We detect features down to ~10^-19 erg/s/cm^2/arcsec^2 with the highest surface brightness regions reaching more than a factor of 100 higher. We find Ly-alpha emission out to ~250 kpc in projection from the active galactic nucleus (AGN). The emission shows arc-like morphologies arising at 150-250 kpc from the nucleus in projection with the connected filamentary structures reaching down into the circum-nuclear region. The most distant arc is offset by 700 km/s relative to circum-nuclear HeII 1640 emission, which we assume to be at the systemic velocity. As we probe emission closer to the nucleus, the filamentary emission narrows in projection on the sky, the relative velocity decreases to ~250 km/s, and line full-width at half maximum range from 300-700 km/s. From UV line ratios, the emission on scales of 10s of kpc from the nucleus along a wide angle in the direction of the radio jets is clearly excited by the radio jets and ionizing radiation of the AGN. Assuming ionization equilibrium, the more extended emission outside of the axis of the jet direction would require 100% or more illumination to explain the observed surface brightness. High speed (>300 km/s) shocks into rare gas would provide sufficiently high surface brightness. We discuss the possibility that the arcs of Ly-alpha emission represent accretion shocks and the filamentary emission represent gas flows into the halo, and compare our results with gas accretion simulations., Comment: 4 pages, 2 figures, 1 table, A&A letters accepted
- Published
- 2017
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36. Comprehensive view of a z~6.5 radio-loud quasi-stellar object: From the radio to the optical/NIR to the X-ray band
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Ighina, L., primary, Caccianiga, A., additional, Moretti, A., additional, Broderick, J.W., additional, Leung, J.K., additional, Paterson, S., additional, Rigamonti, F., additional, Seymour, N., additional, Belladitta, S., additional, Drouart, G., additional, Galvin, T.J., additional, and Hurley-Walker, N., additional
- Published
- 2024
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37. Superconducting Multipole Triplets for the Super Separator Spectrometer
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Aburas, Muhammad, primary, Esper, Alexandre, additional, Bernaudin, Pierre-Emmanuel, additional, Drouart, Antoine, additional, Esnault, Franck, additional, Ghribi, Adnan, additional, Savajols, Hervé, additional, and Stodel, Marc-Hervé, additional
- Published
- 2024
- Full Text
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38. On the frequency of star-forming galaxies in the vicinity of powerful AGNs: The case of SMM J04135+10277
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Fogasy, J., Knudsen, K. K., Lagos, C. D. P., Drouart, G., and Gonzalez-Perez, V.
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
(Abridged) In the last decade several massive molecular gas reservoirs were found <100 kpc distance from active galactic nuclei (AGNs), residing in gas-rich companion galaxies. The study of AGN-gas-rich companion systems opens the opportunity to determine whether the stellar mass of massive local galaxies was formed in their host after a merger event or outside of their host galaxy in a close starbursting companion and later incorporated via mergers. We study the quasar-companion galaxy system of SMM J04135+10277 (z=2.84) and investigate the expected frequency of quasar-starburst galaxy pairs at high redshift using a cosmological galaxy formation model. We use archive data and new APEX ArTeMiS data to construct and model the spectral energy distribution of SMM J04135. We also carry out a comprehensive analysis of the cosmological galaxy formation model GALFORM with the aim of characterising how typical the system of SMM J04135 is and whether quasar-star-forming galaxy pairs may constitute an important stage in galaxy evolution. The companion galaxy of SMM J04135 is a heavily dust-obscured starburst galaxy with a median star formation rate (SFR) of $700\,\rm{M_{\odot}\,yr^{-1}}$, median dust mass of $5.1\times 10^9\,\rm{M_{\odot}}$ and median dust luminosity of $\textrm 9.3 \times 10^{12}\,\rm{L_{\odot}}$. Our simulations, performed at z=2.8, suggest that SMM J04135 is not unique. In fact, at a distance of <100 kpc, 22% of our simulated quasar sample have at least one companion galaxy of a stellar mass $>10^8\, \rm{M_{\odot}}$, and 0.3% have at least one highly star-forming companion ($\rm{SFR}>100\,\rm{M_{\odot}\,yr^{-1}}$). Our results suggest that quasar-gas-rich companion galaxy systems are common phenomena in the early Universe and the high incidence of companions makes the study of such systems crucial to understand the growth and hierarchical build-up of galaxies and black holes., Comment: 10 pages, 5 figures, accepted for publication in A&A
- Published
- 2016
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39. Gas kinematics in powerful radio galaxies at z~2: Energy supply from star formation, AGN, and radio jet
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Nesvadba, N., Drouart, G., De Breuck, C., Best, P., Seymour, N., and Vernet, J.
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Astrophysics - Astrophysics of Galaxies - Abstract
We compare the kinetic energy and momentum injection rates from intense star formation, bolometric AGN radiation, and radio jets with the kinetic energy and momentum observed in the warm ionized gas in 24 powerful radio galaxies at z~2. These galaxies are amongst our best candidates for being massive galaxies near the end of their active formation period, when intense star formation, quasar activity, and powerful radio jets all co-exist. All galaxies have VLT/SINFONI imaging spectroscopy of the rest-frame optical line emission, showing emission-line regions with large velocity offsets (up to 1500 km/s) and line widths (typically 800-1000 km/s) consistent with very turbulent, often outflowing gas. As part of the HeRGE sample, they also have FIR estimates of the star formation and quasar activity obtained with Herschel/PACS and SPIRE, which enables us to measure the relative energy and momentum release from each of the three main sources of feedback in massive, star-forming AGN host galaxies during their most rapid formation phase. We find that star formation falls short by factors 10-1000 of providing the energy and momentum necessary to power the observed gas kinematics. The obscured quasars in the nuclei of these galaxies provide enough energy and momentum in about half of the sample, however, only if these are transfered to the gas relatively efficiently. We compare with theoretical and observational constraints on the efficiency of the energy and momentum transfer from jet and AGN radiation, which advocates that the radio jet is the main driver of the gas kinematics., Comment: A&A accepted. Comments welcome
- Published
- 2016
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40. Estimating sizes of faint, distant galaxies in the submillimetre regime
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Lindroos, L., Knudsen, K. K., Fan, L., Conway, J., Coppin, K., Decarli, R., Drouart, G., Hodge, J. A., Karim, A., Simpson, J. M., and Wardlow, J.
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Astrophysics - Astrophysics of Galaxies - Abstract
We measure the sizes of redshift ~2 star-forming galaxies by stacking data from the Atacama Large Millimeter/submillimeter Array (ALMA). We use a uv-stacking algorithm in combination with model fitting in the uv-domain and show that this allows for robust measures of the sizes of marginally resolved sources. The analysis is primarily based on the 344 GHz ALMA continuum observations centred on 88 sub-millimeter galaxies in the LABOCA ECDFS Submillimeter Survey (ALESS). We study several samples of galaxies at z~2 with $M_* \sim{} 5\times{}10^{10} $ M$_\odot$ , selected using near-infrared photometry (distant red galaxies, extremely red objects, sBzK-galaxies, and galaxies selected on photometric redshift). We find that the typical sizes of these galaxies are ~0.6 arcsec which corresponds to ~5 kpc at z~2, this agrees well with the median sizes measured in the near-infrared z-band (~0.6 arcsec). We find errors on our size estimates of ~0.1-0.2 arcsec, which agree well with the expected errors for model fitting at the given signal-to-noise ratio. With the uv-coverage of our observations (18-160 m), the size and flux density measurements are sensitive to scales out to 2 . We compare this to a simulated ALMA Cycle 3 dataset with intermediate length baseline coverage, and we find that, using only these baselines, the measured stacked flux density would be an order of magnitude fainter. This highlights the importance of short baselines to recover the full flux density of high-redshift galaxies., Comment: Accepted for publication in MNRAS
- Published
- 2016
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41. Starbursts and dusty tori in distant 3CR radio galaxies
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Podigachoski, P., Rocca-Volmerange, B., Barthel, P. D., Drouart, G., and Fioc, M.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present a study of the complete ultraviolet to submillimetre spectral energy distributions (SEDs) of twelve 3CR radio galaxy hosts in the redshift range $1.0 < z < 2.5$, which were all detected in the far-infrared by the Herschel Space Observatory. The study employs the new spectro-chemical evolutionary code P\'EGASE.3, in combination with recently published clumpy AGN torus models. We uncover the properties of the massive host galaxy stellar populations, the AGN torus luminosities, and the properties of the recent starbursts, which had earlier been inferred in these objects from their infrared SEDs. The P\'EGASE.3 fitting yields very luminous (up to 10$^{13}$L$_{\odot}$) young stellar populations with ages of several hundred million years in hosts with masses exceeding 10$^{11}$M$_{\odot}$. Dust masses are seen to increase with redshift, and a surprising correlation -- or better upper envelope behaviour -- is found between the AGN torus luminosity and the starburst luminosity, as revealed by their associated dust components. The latter consistently exceeds the former by a constant factor, over a range of one order of magnitude in both quantities., Comment: 15 pages, 9 figures, accepted for publication in MNRAS
- Published
- 2016
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42. Disentangling star formation and AGN activity in powerful infrared luminous radio galaxies at 1<z<4
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Drouart, Guillaume, Rocca-Volmerange, Brigitte, De Breuck, Carlos, Fioc, Michel, Lehnert, Matthew, Seymour, Nick, Stern, Dan, and Vernet, Joel
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
High-redshift radio galaxies present signs of both star formation and AGN activity, making them ideal candidates to investigate the connection and coevolution of AGN and star formation in the progenitors of present-day massive galaxies. We make use of a sample of 11 powerful radio galaxies spanning 1
- Published
- 2016
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43. Infrared spectral energy distribution decomposition of WISE-selected, hyperluminous hot dust-obscured galaxies
- Author
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Fan, Lulu, Han, Yunkun, Nikutta, Robert, Drouart, Guillaume, and Knudsen, Kirsten K.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We utilize a Bayesian approach to fit the observed mid-IR-to-submm/mm spectral energy distributions (SEDs) of 22 WISE-selected and submm-detected, hyperluminous hot dust-obscured galaxies. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot DOGs into torus and cold dust components. The main results are: 1) Hot DOGs in our submm-detected sample are hyperluminous, with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, averagely contributing ~24% of total IR luminosity. 2) Compared to QSO and starburst SED templates, the median SED of Hot DOGs shows the highest luminosity ratio between mid-IR and submm at rest-frame, while it is very similar to that of QSOs at 10-50um suggesting that the heating sources of Hot DOGs should be buried AGNs. 3) Hot DOGs have both high dust temperatures ~73K and IR luminosity of cold dust. The T-L relation of Hot DOGs suggests that the increase in IR luminosity for Hot DOGs is mostly due to the increase of the dust temperature, rather than dust mass. Hot DOGs have lower dust masses than those of submillimeter galaxies (SMGs) and QSOs within the similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot DOGs can be expected by their relatively high dust temperatures. 4) Hot DOGs have high dust covering factors, which deviate the previously proposed trend of the dust covering factor decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot DOGs by employing a physical model of galaxy evolution. The result suggests that Hot DOGs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst dominated phase to the optically bright QSO phase. (abridged), Comment: 16 pages, 12 figures. Accepted by ApJ
- Published
- 2016
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44. [CII] emission in z ~ 6 strongly lensed, star-forming galaxies
- Author
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Knudsen, Kirsten K., Richard, Johan, Kneib, Jean-Paul, Jauzac, Mathilde, Clement, Benjamin, Drouart, Guillaume, Egami, Eiichi, and Lindroos, Lukas
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The far-infrared fine-structure line [CII] at 1900.5\,GHz is known to be one of the brightest cooling lines in local galaxies, and therefore it has been suggested to be an efficient tracer for star-formation in very high-redshift galaxies. However, recent results for galaxies at $z>6$ have yielded numerous non-detections in star-forming galaxies, except for quasars and submillimeter galaxies. We report the results of ALMA observations of two lensed, star-forming galaxies at $z = 6.029$ and $z=6.703$. The galaxy A383-5.1 (star formation rate [SFR] of 3.2 M$_\odot$ yr$^{-1}$ and magnification of $\mu = 11.4\pm1.9$) shows a line detection with $L_{\rm [CII]} = 8.9\times10^{6}$ L$_\odot$, making it the lowest $L_{\rm [CII]}$ detection at $z>6$. For MS0451-H (SFR = 0.4 M$_\odot$ yr$^{-1}$ and $\mu = 100\pm20$) we provide an upper limit of $L_{\rm [CII]} < 3\times10^{5}$ L$_\odot$, which is 1\,dex below the local SFR-$L_{\rm [CII]}$ relations. The results are consistent with predictions for low-metallicity galaxies at $z>6$, however, other effects could also play a role in terms of decreasing $L_{\rm [CII]}$. The detection of A383-5.1 is encouraging and suggests that detections are possible, but much fainter than initially predicted., Comment: 5 pages, accepted for publication in MNRAS Letters
- Published
- 2016
- Full Text
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45. The Mysterious Morphology of MRC0943-242 as Revealed by ALMA and MUSE
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Gullberg, Bitten, De Breuck, Carlos, Lehnert, Matthew D., Vernet, Joel, Bacon, Roland, Drouart, Guillaume, Emonts, Bjorn, Galametz, Audrey, Ivison, Rob, Nesvadba, Nicole P. H., Richard, Johan, Seymour, Nick, Stern, Daniel, and Wylezalek, Dominika
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We present a pilot study of the z=2.923 radio galaxy MRC0943-242, where we for the first time combine information from ALMA and MUSE data cubes. Even with modest integration times, we disentangle an AGN and a starburst dominated set of components. These data reveal a highly complex morphology, as the AGN, starburst, and molecular gas components show up as widely separated sources in dust continuum, optical continuum and CO line emission observations. CO(1-0) and CO(8-7) line emission suggest that there is a molecular gas reservoir offset from both the dust and the optical continuum that is located ~90kpc from the AGN. The UV line emission has a complex structure in emission and absorption. The line emission is mostly due to i) a large scale ionisation cone energised by the AGN, ii) a Ly-alpha emitting bridge of gas between the radio galaxy and a heavily star-forming set of components. Strangely, the ionisation cone has no Ly-alpha emission. We find this is due to an optically thick layer of neutral gas with unity covering fraction spread out over a region of at least ~100kpc from the AGN. Other, less thick absorption components are associated with Ly-alpha emitting gas within a few tens of kpc from the radio galaxy and are connected by a bridge of emission. We speculate that this linear structure of dust, Ly-alpha and CO emission, and the redshifted absorption seen in the circum-nuclear region may represent an accretion flow feeding gas into this massive AGN host galaxy., Comment: 15 pages, 8 figures, accepted for publication in A&A
- Published
- 2015
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46. ALMA unveils a triple merger and gas exchange in a hyper-luminous radio galaxy at z=2: the Dragonfly Galaxy (II)
- Author
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Emonts, B. H. C., De Breuck, C., Lehnert, M. D., Vernet, J., Gullberg, B., Villar-Martín, M., Nesvadba, N., Drouart, G., Ivison, R., Seymour, N., Wylezalek, D., and Barthel, P.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
The Dragonfly Galaxy (MRC0152-209), at redshift z~2, is one of the most vigorously star-forming radio galaxies in the Universe. What triggered its activity? We present ALMA Cycle 2 observations of cold molecular CO(6-5) gas and dust, which reveal that this is likely a gas-rich triple merger. It consists of a close double nucleus (separation ~4 kpc) and a weak CO-emitter at ~10 kpc distance, all of which have counterparts in HST/NICMOS imagery. The hyper-luminous starburst and powerful radio-AGN were triggered at this precoalescent stage of the merger. The CO(6-5) traces dense molecular gas in the central region, and complements existing CO(1-0) data, which revealed more widespread tidal debris of cold gas. We also find ~10$^{10}$ M(sun) of molecular gas with enhanced excitation at the highest velocities. At least 20-50% of this high-excitation, high-velocity gas shows kinematics that suggests it is being displaced and redistributed within the merger, although with line-of-sight velocities of |v| < 500 km/s, this gas will probably not escape the system. The processes that drive the redistribution of cold gas are likely related to either the gravitational interaction between two kpc-scale discs, or starburst/AGN-driven outflows. We estimate that the rate at which the molecular gas is redistributed is at least ~1200 +- 500 M(sun)/yr, and could perhaps even approach the star formation rate of ~3000 +- 800 M(sun)/yr. The fact that the gas depletion and gas redistribution timescales are similar implies that dynamical processes can be important in the evolution of massive high-z galaxies., Comment: Accepted for publication in A&A (6 pages, 5 figures)
- Published
- 2015
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47. A CO-rich merger shaping a powerful and hyper-luminous infrared radio galaxy at z=2: the Dragonfly Galaxy
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Emonts, B. H. C., Mao, M. Y., Stroe, A., Pentericci, L., Villar-Martin, M., Norris, R. P., Miley, G., De Breuck, C., van Moorsel, G. A., Lehnert, M. D., Carilli, C. L., Rottgering, H. J. A., Seymour, N., Sadler, E. M., Ekers, R. D., Drouart, G., Feain, I., Colina, L., Stevens, J., and Holt, J.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
In the low-redshift Universe, the most powerful radio sources are often associated with gas-rich galaxy mergers or interactions. We here present evidence for an advanced, gas-rich (`wet') merger associated with a powerful radio galaxy at a redshift of z~2. This radio galaxy, MRC 0152-209, is the most infrared-luminous high-redshift radio galaxy known in the southern hemisphere. Using the Australia Telescope Compact Array, we obtained high-resolution CO(1-0) data of cold molecular gas, which we complement with HST/WFPC2 imaging and WHT long-slit spectroscopy. We find that, while roughly M(H2) ~ 2 x 10$^{10}$ M$_{\odot}$ of molecular gas coincides with the central host galaxy, another M(H2) ~ 3 x 10$^{10}$ M$_{\odot}$ is spread across a total extent of ~60 kpc. Most of this widespread CO(1-0) appears to follow prominent tidal features visible in the rest-frame near-UV HST/WFPC2 imaging. Ly$\alpha$ emission shows an excess over HeII, but a deficiency over L(IR), which is likely the result of photo-ionisation by enhanced but very obscured star formation that was triggered by the merger. In terms of feedback, the radio source is aligned with widespread CO(1-0) emission, which suggests that there is a physical link between the propagating radio jets and the presence of cold molecular gas on scales of the galaxy's halo. Its optical appearance, combined with the transformational stage at which we witness the evolution of MRC 0152-209, leads us to adopt the name `Dragonfly Galaxy'., Comment: Accepted for publication in MNRAS (12 pages, 5 figures)
- Published
- 2015
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48. Supernova remnant mass cumulated along the star formation history of the z=3.8 radiogalaxies 4C41.17 and TN J2007-1316
- Author
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Rocca-Volmerange, Brigitte, Drouart, Guillaume, and De Breuck, Carlos
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
In this paper, we show that the supernova remnant (SNR) masses cumulated from core-collapse supernovae along the star formation history of two powerful z=3.8 radio galaxies 4C41.17 and TN J2007-1316 reach up to > 10^9 Msun, comparable with supermassive black hole (SMBH) masses measured from the SDSS sample at similar redshifts. The SNR mass is measured from the already exploded supernova mass after subtraction of ejecta at the galaxy age where the mass of still luminous stars fits at best the observed spectral energy distribution (SED), continuously extended to the optical-Spitzer-Herschel-submm domains, with the help of the galaxy evolution model P\'egase.3. For the recent and old stellar populations, SNR masses vary on 10^(9 to 10) Msun and the SNR-to-star mass ratio between 1 and 0.1 percent is comparable to the observed low-z SMBH-to-star mass ratio. For the template radio galaxy 4C41.17, SNR and stellar population masses estimated from large aperture (>4arcsec=30kpc) observations are compatible, within one mass order, with the total mass of multiple optical HST (~700pc) structures, associated with VLA radio emissions, both at 0.1 arcsec. Probing the SNR accretion by central black holes is a simple explanation for SMBH growth, requiring physics on star formation, stellar and galaxy dynamics with consequences on various processes (quenching, mergers, negative feedback) and a key to the relation bulge-SMBH., Comment: 13 pages, 2 double figures, 1 table, accepted for publication in Astrophysical Journal Letters, in press
- Published
- 2015
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49. Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project
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Drouart, G., De Breuck, C., Vernet, J., Seymour, N., Lehnert, M., Barthel, P., Bauer, F. E., Ibar, E., Galametz, A., Haas, M., Hatch, N., Mullaney, J. R., Nesvadba, N., Rocca-Volmerange, B., Rottgering, H. J. A., Stern, D., and Wylezalek, D.
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We present results from a survey of 70 radio galaxies (RGs) at redshifts 1
2.5 are higher than the sSFR of typical star-forming galaxies over the same redshift range but are similar or perhaps lower than the galaxy population for RGs at z<2.5. By comparing the sSFR and the specific black hole mass accretion rate, we conclude that BHs in radio loud AGN are already, or soon will be, overly massive compared to their host galaxies in terms of expectations from the local MBH-MGal relation. In order to ``catch up'' with the BH, the galaxies require about an order-of magnitude more time to grow in mass, at the observed SFRs, compared to the time the BH is actively accreting. However, during the current cycle of activity, we argue that this catching-up is likely to be difficult due to the short gas depletion times. Finally, we speculate on how the host galaxies might grow sufficiently in stellar mass to ultimately fall onto the local MBH-MGal relation., Comment: 37 pages, accepted to A&A - Published
- 2014
- Full Text
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50. The molecular gas content of ULIRG type 2 quasars at z < 1
- Author
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Rodríguez, M. I., Villar-Martín, M., Emonts, B., Humphrey, A., Drouart, G., Burillo, S. García, and Torres, M. Pérez
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We present new results of CO(1-0) spectroscopic observations of 4 SDSS type 2 quasars (QSO2) at z$\sim$0.3, observed with the 30m IRAM telescope. The QSO2 have infrared luminosities in the ULIRG (UltraLuminous Infrared Galaxies) regime. We confirm the CO(1-0) detection in one of our 4 QSO2, SDSS J1543-00, with $L'_{CO}$ and $M_{H_2}$ (1.2$\pm$0.2) $\times$10$^{10}$ K km s$^{-1}$ pc$^2$ and (9.4$\pm$1.4)$\times$10$^9$ M$_{\odot}$, respectively. The CO(1-0) line has $FWHM=$575$\pm$102 km s$^{-1}$. No CO(1-0) emission is detected in SDSS J0903+02, SDSS J1337-01, SDSS J1520-01 above 3 sigma, yielding upper limits on $M(H_2)\sim$ 9.6, 4.3 and 5.1 $\times$10$^9$ M$_{\odot}$ respectively. Together with CO measurements of 9 QSO2 at $z\sim$0.3-1.0 from the ULIRG sample by Combes et al. (2011, 2013), we expand previous studies of the molecular gas content of intermediate $z$ QSO2 into the ULIRG regime. We discuss the location of the 13 ULIRG QSO2 at $z<$1 with available $L'_{CO}$ measurements in the $L'_{CO}$ vs. $z$ and $L'_{CO}$ vs. $L_{FIR}$ diagrams, in comparison with other QSO1 and ULIRG star forming samples., Comment: 4 pages, 2 figures, Accepted for publication in A&A
- Published
- 2014
- Full Text
- View/download PDF
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