468 research outputs found
Testing the evolutionary link between submillimetre galaxies and quasars: CO observations of QSOs at z~2
No full textWe have used the IRAM Plateau de Bure millimetre interferometer and the UKIRT 1–5 μm Imager Spectrometer (UIST) to test the connection between the major phases of spheroid growth and nuclear accretion by mapping CO emission in nine submillimetre-detected QSOs at z= 1.7–2.6 with black hole (BH) masses derived from near-infrared spectroscopy. When combined with one QSO obtained from the literature, we present sensitive CO(3–2) or CO(2–1) observations of 10 submillimetre-detected QSOs selected at the epoch of peak activity in both QSOs and submillimetre (submm) galaxies (SMGs). CO is detected in 5/6 very optically luminous (MB∼−28) submm-detected QSOs with BH masses MBH≃ 109–1010 M⊙, confirming the presence of large gas reservoirs of Mgas≃ 3.4 × 1010 M⊙. Our BH masses and dynamical mass constraints on the host spheroids suggest, at face value, that these optically luminous QSOs at z= 2 lie about an order of magnitude above the local BH–spheroid relation, MBH/Msph, although this result is dependent on the size and inclination of the CO-emitting region. However, we find that their BH masses are ∼30 times too large and their surface density is ∼300 times too small to be related to typical SMGs in an evolutionary sequence. Conversely, we measure weaker CO emission in four fainter (MB∼−25) submm-detected QSOs with properties, BH masses (MBH≃ 5 × 108 M⊙), and surface densities similar to SMGs. These QSOs appear to lie near the local MBH/Msph relation, making them plausible ‘transition objects’ in the proposed evolutionary sequence linking QSOs to the formation of massive young galaxies and BHs at high redshift. We show that SMGs have a higher incidence of bimodal CO line profiles than seen in our QSO sample, which we interpret as an effect of their relative inclinations, with the QSOs seen more face-on. Finally, we find that the gas masses of the four fainter submm-detected QSOs imply that their star formation episodes could be sustained for ∼10 Myr, and are consistent with representing a phase in the formation of massive galaxies which overlaps a preceding SMG starburst phase, before subsequently evolving into a population of present-day massive ellipticals
Colour matters: the effects of lensing on the positional offsets between optical and submillimetre galaxies in Herschel★-ATLAS
No full textWe report an unexpected variation in the positional offset distributions between Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) submillimetre (submm) sources and their optical associations, depending on both 250-mu m signal-to-noise ratio and 250/350-mu m colour. We show that redder and brighter submm sources have optical associations with a broader distribution of positional offsets than would be expected if these offsets were due to random positional errors in the source extraction. The observation can be explained by two possible effects: either red submm sources trace a more clustered population than blue ones, and their positional errors are increased by confusion, or red submm sources are generally at high redshifts and are frequently associated with low-redshift lensing structures which are identified as false counterparts. We perform various analyses of the data, including the multiplicity of optical associations, the redshift and magnitude distributions in H-ATLAS in comparison to HerMES, and simulations of weak lensing, and we conclude that the effects are most likely to be explained by widespread weak lensing of Herschel-SPIRE sources by foreground structures. This has important consequences for counterpart identification and derived redshift distributions and luminosity functions of submm surveys.</p
Chandra reveals a luminous Compton-thick QSO powering a Ly α blob in a z = 4 starbursting protocluster
No full textContext. Galaxy clusters in the local universe descend from high-redshift overdense regions known as protoclusters. The large gas reservoirs and high rate of galaxy interaction in protoclusters are expected to enhance star-formation activity and trigger luminous supermassive black-hole accretion in the nuclear regions of the host galaxies. Aims. We investigated the active galactic nucleus (AGN) content of a gas-rich and starbursting protocluster at z = 4.002, known as the Distant Red Core (DRC). In particular, we search for luminous and possibly obscured AGN in 13 identified members of the structure, and compare the results with protoclusters at lower redshifts. We also test whether a hidden AGN can power the Lyα blob (LAB) detected with VLT/MUSE in the DRC. Methods. We observed all of the identified members of the structure with 139 ks of Chandra ACIS-S imaging. Being less affected by absorption than optical and IR bands, even in the presence of large column densities of obscuring material, X-ray observations are the best tools to detect ongoing nuclear activity in the DRC galaxies. Results. We detect obscured X-ray emission from the two most gas-rich members of the DRC, named DRC-1 and DRC-2. Both of them are resolved into multiple interacting clumps in high-resolution Atacama Large Millimeter Array and Hubble Space Telescope observations. In particular, DRC-2 is found to host a luminous (L2-10 keV ≈ 3 × 1045 erg s-1) Compton-thick (NH 1024 cm-2) quasar (QSO) candidate, comparable to the most luminous QSOs known at all cosmic times. The AGN fraction among DRC members is consistent with results found for lower redshift protoclusters. However, X-ray stacking analysis reveals that supermassive black hole (SMBH) accretion is likely also taking place in other DRC galaxies that are not detected individually by Chandra. Conclusions. The luminous AGN detected in the most gas-rich galaxies in the DRC and the widespread SMBH accretion in the other members, which is suggested by stacking analysis, point toward the presence of a strong link between large gas reservoirs, galaxy interactions, and luminous and obscured nuclear activity in protocluster members. The powerful and obscured QSO detected in DRC-2 is likely powering the nearby LAB detected with VLT/MUSE, possibly through photoionization; however, we propose that the diffuse Lyα emission may be due to gas shocked by a massive outflow launched by DRC-2 over a ≈10 kpc scale
Herschel-ATLAS : deep HST/WFC3 imaging of strongly lensed submillimetre galaxies
No full textThis work is supported by STFC (grants PP/D002400/1 and ST/G002533/1)We report on deep near-infrared observations obtained with the Wide Field Camera-3 (WFC3) onboard the Hubble Space Telescope (HST) of the first five confirmed gravitational lensing events discovered by the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). We succeed in disentangling the background galaxy from the lens to gain separate photometry of the two components. The HST data allow us to significantly improve on previous constraints of the mass in stars of the lensed galaxy and to perform accurate lens modelling of these systems, as described in the accompanying paper by Dye et al. We fit the spectral energy distributions of the background sources from near-IR to millimetre wavelengths and use the magnification factors estimated by Dye et al. to derive the intrinsic properties of the lensed galaxies. We find these galaxies to have star-formations rates (SFR) ∼ 400–2000 M⊙ yr−1, with ∼(6–25) × 1010 M⊙ of their baryonic mass already turned into stars. At these rates of star formation, all remaining molecular gas will be exhausted in less than ∼100 Myr, reaching a final mass in stars of a few 1011 M⊙. These galaxies are thus proto-ellipticals caught during their major episode of star formation, and observed at the peak epoch (z ∼ 1.5–3) of the cosmic star formation history of the Universe.Peer reviewe
Iram 30-m-emir redshift search of z=3-4 lensed dusty starbursts selected from the herbs sample
No full text(…) European Union Seventh Framework Programme ([FP7/2007–2013] [FP&/2007– 2011]) under grant agreement no. 607254; IGN (Spain); HD acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2014 Ramón y Cajal program RYC-2014-15686 and AYA2017-84061-P, the later one co-financed by FEDER (European Regional Development Funds). JGN acknowledges financial support from the PGC 2018 project PGC2018-101948-B-I00 (MICINN and FEDER), the PAPI-19-EMERG-11 (Universidad de Oviedo) and the Spanish MINECO ‘Ramón y Cajal’ fellowship (RYC-2013-13256). IPF acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN) under grant number ESP2017-86852-C4-2-R (…)Bakx, T.J.L.C., Dannerbauer, H., Frayer, D., Eales, S.A., Pérez-Fournon, I., Cai, Z.-Y., Clements, D.L., de Zotti, G., González-Nuevo, J., Ivison, R.J., Lapi, A., Michałowski, M.J., Negrello, M., Serjeant, S., Smith, M.W.L., Temi, P., Urquhart, S., van der Werf, P
The star formation rates of QSOs
No full textMS and MJP acknowledge support by the Science and Technology Facilities Council [ST/S000216/1]. NM acknowledges support of the LMU Faculty of Physics. EI acknowledges partial support from FONDECYT through grant N◦ 1171710. MJM acknowledges the support of the National Science Centre, Poland through the SONATA BIS grant 2018/30/E/ST9/00208. JGN acknowledges financial support from the PGC 2018 project PGC2018-101948-B-I00 (MICINN, FEDER), PAPI-19-EMERG-11 (Universidad de Oviedo) and for a ‘Ramon y Cajal’ fellowship (RYC-2013-13256) from the Spanish
MINECO.Symeonidis M., Maddox N., Jarvis M.J., Michałowski M.J., Andreani P., Clements D.L., De Zotti G., Duivenvoorden S., Gonzalez-Nuevo J., Ibar E., Ivison R.J., Leeuw L., Page M.J., Shirley R., Smith M.W.L., Vaccari M
Bright extragalactic ALMA redshift survey (BEARS) III: detailed study of emission lines from 71 Herschel targets
No full textThe European Science
Cluster of Astronomy and Particle Physics ESFRI Research Infrastructures has received funding from the European Union’s Horizon
2020 research and innovation programme under Grant Agreement
No. 824064. CY acknowledges support from
ERC Advanced Grant 789410 (...)Hagimoto, M., Bakx, T.J.L.C., Serjeant, S., Bendo, G.J., Urquhart, S.A., Eales, S., Harrington, K.C., Tamura, Y., Umehata, H., Berta, S., Cooray, A.R., Cox, P., De Zotti, G., Lehnert, M.D., Riechers, D.A., Scott, D., Temi, P., Van Der Werf, P.P., Yang, C., Amvrosiadis, A., Andreani, P.M., Baker, A.J., Beelen, A., Borsato, E., Buat, V., Butler, K.M., Dannerbauer, H., Dunne, L., Dye, S., Enia, A.F.M., Fan, L., Gavazzi, R., González-Nuevo, J., Harris, A.I., Herrera, C.N., Hughes, D.H., Ismail, D., Ivison, R.J., Jones, B., Kohno, K., Krips, M., Lagache, G., Marchetti, L., Massardi, M., Messias, H., Negrello, M., Neri, R., Omont, A., Perez-Fournon, I., Sedgwick, C., Smith, M.W.L., Stanley, F., Verma, A., Vlahakis, C., Ward, B., Weiner, C., Weiß, A., Young, A.J
Extremely red objects in the UKIDSS Ultra Deep Survey Early Data Release
No full textWe construct a sample of extremely red objects (EROs) within the UKIDSS Ultra Deep Survey by combining the Early Data Release with optical data from the Subaru/XMM–Newton Deep Field. We find a total of 3715 objects over 2013 arcmin2 with R−K > 5.3 and K≤ 20.3, which is a higher surface density than found by previous studies. This is partly due to our ability to use a small aperture in which to measure colours, but is also the result of a genuine overdensity of objects compared to other fields. We separate our sample into passively evolving and dusty star-forming galaxies using their RJK colours and investigate their radio properties using a deep radio map. The dusty population has a higher fraction of individually detected radio sources and a higher mean radio flux density among the undetected objects, but the passive population has a higher fraction of bright radio sources, suggesting that active galactic nuclei are more prevalent among the passive ERO population
The SCUBA half-degree extragalactic survey - I. Survey motivation, design and data processing
No full textThe Submillimetre Common-User Bolometer Array ( SCUBA) Half-Degree Extragalactic Survey ( SHADES) is a major new blank-field extragalactic submillimetre (submm) survey currently underway at the James Clerk Maxwell Telescope (JCMT). Ultimately, SHADES aims to cover half a square degree at 450 and 850 mu m to a 4 sigma depth of similar or equal to 8 mJy at 850 mu m. Two fields are being observed, the Subaru/XMM-Newton Deep Field (SXDF) (02(h)18(m) - 05 degrees.) and the Lockman Hole East (10(h)52(m) + 57 degrees). The survey has three main aims: (i) to investigate the population of high-redshift submm galaxies and the cosmic history of massive dust-enshrouded star formation activity; (ii) to investigate the clustering properties of submm-selected galaxies in order to determine whether these objects could be progenitors of present-day massive ellipticals; and (iii) to investigate the fraction of submm-selected sources that harbour active galactic nuclei. To achieve these aims requires that the submm data be combined with cospatial information spanning the radio-to-X-ray frequency range. Accordingly, SHADES has been designed to benefit from ultra-deep radio imaging obtained with the Very Large Array (VLA), deep mid-infrared observations from the Spitzer Space Telescope, submm mapping by the Balloon-borne Large Aperture Submillimetre Telescope ( BLAST), deep near-infrared imaging with the United Kingdom Infrared Telescope, deep optical imaging with the Subaru Telescope and deep X-ray observations with the XMM-Newton observatory. It is expected that the resulting extensive multiwavelength data set will provide complete photometric redshift information accurate to delta(z) 3 sigma at 850 mu m. Although uncorrected for Eddington bias, this source density is more than sufficient for providing enough sources to answer the science goals of SHADES, once half a square degree is observed. A refined reanalysis of the original 8-mJy survey Lockman hole data was carried out in order to evaluate the new data-reduction pipeline. Of the 17 most secure sources in the original sample, 12 have been reconfirmed, including 10 of the 11 for which radio identifications were previously secured
NOEMA confirmation of an optically dark ALMA–AzTEC submillimetre galaxy at
No full textWe have obtained deep 1 and 3 mm spectral-line scans towards a candidate z ≳ 5 ALMA-identified AzTEC submillimetre galaxy (SMG) in the Subaru/XMM-Newton Deep Field (or UKIDSS UDS), ASXDF1100.053.1, using the NOrthern Extended Millimeter Array (NOEMA), aiming to obtain its spectroscopic redshift. ASXDF1100.053.1 is an unlensed optically dark millimetre-bright SMG with S1100 μm = 3.5 mJy and KAB > 25.7 (2σ), which was expected to lie at z = 5–7 based on its radio–submillimetre photometric redshift. Our NOEMA spectral scan detected line emission due to 12CO(J = 5–4) and (J = 6–5), providing a robust spectroscopic redshift, zCO = 5.2383 ± 0.0005. Energy-coupled spectral energy distribution modelling from optical to radio wavelengths indicates an infrared luminosity L⊙, a star formation rate SFR M⊙ yr−1, a dust mass M⊙, a stellar mass M⊙, and a dust temperature K. The CO luminosity allows us to estimate a gas mass Mgas = 3.1 ± 0.3 × 1010 M⊙, suggesting a gas-to-dust mass ratio of around 70, fairly typical for z ∼ 2 SMGs. ASXDF1100.053.1 has ALMA continuum size kpc, so its surface infrared luminosity density ΣIR is L⊙ kpc−2. These physical properties indicate that ASXDF1100.053.1 is a massive dusty star-forming galaxy with an unusually compact starburst. It lies close to the star-forming main sequence at z ∼ 5, with low Mgas/Mstellar = 0.09, SFR/SFRMS(RSB) = 0.6, and a gas-depletion time τdep of ≈50 Myr, modulo assumptions about the stellar initial mass function in such objects. ASXDF1100.053.1 has extreme values of Mgas/Mstellar, RSB, and τdep compared to SMGs at z ∼ 2–4, and those of ASXDF1100.053.1 are the smallest among SMGs at z > 5. ASXDF1100.053.1 is likely a late-stage dusty starburst prior to passivisation. The number of z = 5.1–5.3 unlensed SMGs now suggests a number density dN/dz = 30.4 ± 19.0 deg−2, barely consistent with the latest cosmological simulations
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