ALBERT

Description: We exploit Atacama Large Interferometer Array (ALMA) 870 μm observations to measure the star formation rates (SFRs) of eight X-ray detected active galactic nuclei (AGNs) in a z 3.1 protocluster, four of which reside in extended Lyα haloes (often termed Lyman-alpha blobs: LABs). Three of the AGNs are detected by ALMA and have implied SFRs of 220–410 M  yr –1 ; the non-detection of the other five AGNs places SFR upper limits of 210 M  yr –1 . The mean SFR of the protocluster AGNs (110–210 M  yr –1 ) is consistent (within a factor of 0.7–2.3) with that found for co-eval AGNs in the field, implying that the galaxy growth is not significantly accelerated in these systems. However, when also considering ALMA data from the literature, we find evidence for elevated mean SFRs (up-to a factor of 5.9 over the field) for AGNs at the protocluster core, indicating that galaxy growth is significantly accelerated in the central regions of the protocluster. We also show that all of the four protocluster LABs are associated with an ALMA counterpart within the extent of their Lyα emission. The SFRs of the ALMA sources within the LABs (150–410 M  yr –1 ) are consistent with those expected for co-eval massive star-forming galaxies in the field. Furthermore, the two giant LABs (with physical extents of 100 kpc) do not host more luminous star formation than the smaller LABs, despite being an order of magnitude brighter in Lyα emission. We use these results to discuss star formation as the power source of LABs.

Description: We present new [C i ](1–0) and 12 CO(4–3) Plateau de Bure Interferometer observations of five sub-millimeter galaxies (SMGs) and combine these with all available [C i ](1–0) literature detections in SMGs to probe the gas distribution within a sample of 14 systems. We explore the [C i ](1–0) properties of the SMG population, particularly investigating the ratio of the [C i ](1–0) luminosity to various 12 CO transition and far-infrared luminosities. We find that the SMGs with new observations extend the spread of L [C i ](1-0) / L FIR to much higher values than found before, with our complete sample providing a good representation of the diverse z  〉 2 SMG population. We compare the line ratios to the outputs of photodissociation region (PDR) models to constrain the physical conditions in the interstellar medium (ISM) of the SMGs, finding an average density of 〈log ( n /cm –3 )〉 = 4.3 ± 0.2 and an average radiation field (in terms of the local field value, G 0 ) of 〈log ( G 0 )〉 = 3.9 ± 0.4. Overall, we find the SMGs are most comparable to local ultraluminous infrared galaxies (ULIRGs) in G 0 and n ; however, a significant tail of 5 of the 14 SMGs are likely best compared to less compact, local starburst galaxies, providing new evidence that many SMGs have extended star formation distributions and are therefore not simply scaled up versions of local ULIRGs. We derive the ISM properties of a sample of quasars also finding that they have higher densities and radiation fields on average than the SMGs, consistent with the more extreme local ULIRGs, and reinforcing their interpretation as transition objects. We explore the limitations of using simple PDR models to understand [C i ], which may be concomitant with the bulk H 2 mass rather than PDR distributed. We therefore also assess [C i ] as a tracer of H 2 , finding that for our sample SMGs, the H 2 masses derived from [C i ] are often consistent with those determined from low excitation 12 CO. We conclude that [C i ] observations provide a useful tool to probe the bulk gas and gas processes occurring within merging SMGs, however more detailed, resolved observations are required to fully exploit [C i ] as a diagnostic.

Description: We present adaptive optics-assisted integral field spectroscopy around the Hα or Hβ lines of 12 gravitationally lensed galaxies obtained with VLT/SINFONI, Keck/OSIRIS and Gemini/NIFS. We combine these data with previous observations and investigate the dynamics and star formation properties of 17 lensed galaxies at 1 〈  z  〈 4. Thanks to gravitational magnification of 1.4–90 times by foreground clusters, effective spatial resolutions of 40–700 pc are achieved. The magnification also allows us to probe lower star formation rates (SFRs) and stellar masses than unlensed samples; our target galaxies feature dust-corrected SFRs derived from Hα or Hβ emission of ~0.8–40 M  yr –1 , and stellar masses M *  ~ 4 10 8 –6 10 10  M . All of the galaxies show velocity gradients, with 59 per cent consistent with being rotating discs and a likely merger fraction of 29 per cent, with the remaining 12 per cent classed as ‘undetermined’. We extract 50 star-forming clumps with sizes in the range 60 pc–1 kpc from the Hα (or Hβ) maps, and find that their surface brightnesses, clump and their characteristic luminosities, L 0 , evolve to higher luminosities with redshift. We show that this evolution can be described by fragmentation on larger scales in gas-rich discs, and is likely to be driven by evolving gas fractions.

Description: We present the first results from the KMOS ( K -band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASH z ), a VLT/KMOS integral-field spectroscopic (IFS) survey of z 0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN ( L 2–10 keV = 10 42 –10 45  erg s –1 ), for which we observed [O iii ] ( z 1.1–1.7) or Hα emission ( z 0.6–1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the [O iii ] targets, 50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall line widths 600 km s –1 ). The most luminous half (i.e. L X 〉 6 x 10 43  erg s –1 ) have a 2 times higher incidence of such velocities. On the basis of our results, we find no evidence that X-ray obscured AGN are more likely to host extreme kinematics than unobscured AGN. Our KASH z sample has a distribution of gas velocities that is consistent with a luminosity-matched sample of z 〈 0.4 AGN. This implies little evolution in the prevalence of ionized outflows, for a fixed AGN luminosity, despite an order-of-magnitude decrease in average star formation rates over this redshift range. Furthermore, we compare our Hα targets to a redshift-matched sample of star-forming galaxies and despite a similar distribution of Hα luminosities and likely star formation rates, we find extreme ionized gas velocities are up to 10 times more prevalent in the AGN-host galaxies. Our results reveal a high prevalence of extreme ionized gas velocities in high-luminosity X-ray AGN and imply that the most powerful ionized outflows in high-redshift galaxies are driven by AGN activity.

Description: We present Multi Unit Spectroscopic Explorer (MUSE) integral field unit spectroscopic observations of the ~150 kpc Lyα halo around the z  = 4.1 radio galaxy TN J1338–1942. This 9-h observation maps the full two-dimensional kinematics of the Lyα emission across the halo, which shows a velocity gradient of v ~ 700 km s –1 across 150 kpc in projection, and also identified two absorption systems associated with the Lyα emission from the radio galaxy. Both absorbers have high covering fractions (~1) spanning the full ~150 80 kpc 2 extent of the halo. The stronger and more blueshifted absorber ( v ~ –1200 km s –1 from the systemic) has dynamics that mirror that of the underlying halo emission and we suggest that this high column material ( n (H i ) ~ 10 19.4  cm –2 ), which is also seen in C iv absorption, represents an outflowing shell that has been driven by the active galactic nuclei (AGN) or the star formation within the galaxy. The weaker ( n (H i ) ~ 10 14  cm –2 ) and less blueshifted ( v ~ –500 km s –1 ) absorber most likely represents material in the cavity between the outflowing shell and the Lyα halo. We estimate that the mass in the shell must be ~10 10  M – a significant fraction of the interstellar medium from a galaxy at z  = 4. The large scales of these coherent structures illustrate the potentially powerful influence of AGN feedback on the distribution and energetics of material in their surroundings. Indeed, the discovery of high-velocity (~1000 km s –1 ), group-halo-scale (i.e. 〉150 kpc) and mass-loaded winds in the vicinity of the central radio source is in agreement with the requirements of models that invoke AGN-driven outflows to regulate star formation and black hole growth in massive galaxies.

Description: We present a Herschel /Spectral and Photometric Imaging Receiver (SPIRE) survey of three protoclusters at z = 2–3 (2QZCluster, HS1700, SSA22). Based on the SPIRE colours ( S 350 / S 250 and S 500 / S 350 ) of 250 μm sources, we selected high-redshift dusty star-forming galaxies potentially associated with the protoclusters. In the 2QZCluster field, we found a 4 overdensity of six SPIRE sources around 4.5 arcmin (~2.2 Mpc) from a density peak of H α emitters at z = 2.2. In the HS1700 field, we found a 5 overdensity of eight SPIRE sources around 2.1 arcmin (~1.0 Mpc) from a density peak of Lyman-break galaxies at z = 2.3. We did not find any significant overdensities in SSA22 field, but we found three 500 μm sources are concentrated 3 arcmin (~1.4 Mpc) east to the Ly α emitters overdensity. If all the SPIRE sources in these three overdensities are associated with protoclusters, the inferred star formation rate densities are 10 3 –10 4 times higher than the average value at the same redshifts. This suggests that dusty star formation activity could be very strongly enhanced in z ~ 2–3 protoclusters. Further observations are needed to confirm the redshifts of the SPIRE sources and to investigate what processes enhance the dusty star formation activity in z ~ 2–3 protoclusters.

Description: We present an Integral Field Unit survey of 73 galaxy clusters and groups with the VIsible Multi Object Spectrograph on the Very Large Telescope. We exploit the data to determine the H α gas dynamics on kpc scales to study the feedback processes occurring within the dense cluster cores. We determine the kinematic state of the ionized gas and show that the majority of systems (~2/3) have relatively ordered velocity fields on kpc scales that are similar to the kinematics of rotating discs and are decoupled from the stellar kinematics of the brightest cluster galaxy. The majority of the H α flux (〉50 per cent) is typically associated with these ordered kinematics and most systems show relatively simple morphologies suggesting they have not been disturbed by a recent merger or interaction. Approximately 20 per cent of the sample (13/73) have disturbed morphologies which can typically be attributed to active galactic nuclei activity disrupting the gas. Only one system shows any evidence of an interaction with another cluster member. A spectral analysis of the gas suggests that the ionization of the gas within cluster cores is dominated by non-stellar processes, possibly originating from the intracluster medium itself.

Description: To investigate what drives the reversal of the morphology–density relation at intermediate/high redshift, we present a multiwavelength analysis of 27 dusty starburst galaxies in the massive cluster Cl 0024+17 at z  = 0.4. We combine Hα dynamical maps from the VLT/FLAMES multi-IFU system with far-infrared imaging using Herschel /SPIRE and millimetre spectroscopy from IRAM/NOEMA, in order to measure the dynamics, star formation rates and gas masses of this sample. Most galaxies appear to be rotationally supported, with a median ratio of rotational-support to line-of-sight velocity dispersion v / ~ 5 ± 2, and specific angular momentum R  = 0.83 ± 0.06 – comparable to field spirals of a similar mass at this redshift. The star formation rates of 3–26 M  yr –1 and average 12 CO-derived gas mass of ~ 1  x  10 10  M suggest gas depletion time-scales of ~1 Gyr (~0.25 of the cluster crossing time). We derive characteristic dust temperatures (mean T d  = 26 ± 1 K) consistent with local galaxies of similar far-infrared luminosity, suggesting that the low-density gas is yet to be stripped. Taken together, these results suggest that these starbursts have only recently accreted from the field, with star formation rates likely enhanced due to the effects of ram pressure. In order to make the transition to cluster S0s these galaxies must lose ~40 per cent of their specific angular momentum. We suggest this must occur ≥1 Gyr later, after the molecular gas has been depleted and/or stripped, via multiple tidal interactions with other cluster members.

Description: We present Early Science observations with the Large Millimeter Telescope, AzTEC 1.1 mm continuum images and wide bandwidth spectra (73–111 GHz) acquired with the Redshift Search Receiver, towards four bright lensed submillimetre galaxies identified through the Herschel Lensing Survey-snapshot and the Submillimetre Common-User Bolometer Array-2 Cluster Snapshot Survey. This pilot project studies the star formation history and the physical properties of the molecular gas and dust content of the highest redshift galaxies identified through the benefits of gravitational magnification. We robustly detect dust continuum emission for the full sample and CO emission lines for three of the targets. We find that one source shows spectroscopic multiplicity and is a blend of three galaxies at different redshifts ( z  = 2.040, 3.252, and 4.680), reminiscent of previous high-resolution imaging follow-up of unlensed submillimetre galaxies, but with a completely different search method, that confirm recent theoretical predictions of physically unassociated blended galaxies. Identifying the detected lines as 12 CO ( J up  = 2–5) we derive spectroscopic redshifts, molecular gas masses, and dust masses from the continuum emission. The mean H 2 gas mass of the full sample is (2.0 ± 0.2)  x  10 11 M /μ, and the mean dust mass is (2.0 ± 0.2)  x  10 9 M /μ, where μ  2–5 is the expected lens amplification. Using these independent estimations we infer a gas-to-dust ratio of GDR   55–75, in agreement with other measurements of submillimetre galaxies. Our magnified high-luminosity galaxies fall on the same locus as other high-redshift submillimetre galaxies, extending the $L^{\prime }_{\rm CO}$ – L FIR correlation observed for local luminous and ultraluminous infrared galaxies to higher far-infrared and CO luminosities.

Description: We study the 850-μm emission in X-ray-selected active galactic nuclei (AGN) in the ~2 deg 2 COSMOS field using new data from the SCUBA-2 Cosmology Legacy Survey. We find 19 850-μm bright X-ray AGN in a ‘high-sensitivity’ region covering 0.89 deg 2 with flux densities of S 850 = 4–10 mJy. The 19 AGN span the full range in redshift and hard X-ray luminosity covered by the sample – 0.7   z   3.5 and 43.2  log 10 ( L X )  45. We report a highly significant stacked 850-μm detection of a hard X-ray flux-limited population of 699 z  〉 1 X-ray AGN – S 850  = 0.71 ± 0.08 mJy. We explore trends in the stacked 850-μm flux densities with redshift, finding no evolution in the average cold dust emission over the redshift range probed. For type 1 AGN, there is no significant correlation between the stacked 850-μm flux and hard X-ray luminosity. However, in type 2 AGN the stacked submillimeter flux is a factor of 2 higher at high luminosities. When averaging over all X-ray luminosities, no significant differences are found in the stacked submillimeter fluxes of type 1 and type 2 AGN as well as AGN separated on the basis of X-ray hardness ratios and optical-to-infrared colours. However, at log 10 ( L 2 – 10 /erg s –1 ) 〉 44.4, dependences in average submillimeter flux on the optical-to-infrared colours become more pronounced. We argue that these high-luminosity AGN represent a transition from a secular to a merger-driven evolutionary phase where the star formation rates and accretion luminosities are more tightly coupled. Stacked AGN 850-μm fluxes are compared to the stacked fluxes of a mass-matched sample of K -band-selected non-AGN galaxies. We find that at 10.5 〈log 10 ( M * /M )〈11.5, the non-AGN 850-μm fluxes are 1.5–2 times higher than in type 2 AGN of equivalent mass. We suggest these differences are due to the presence of massive dusty, red starburst galaxies in the K -band-selected non-AGN sample, which are not present in optically selected catalogues covering a smaller area.