FIR Luminosity Research Articles

Massive black holes in high-redshift Lyman Break Galaxies

ABSTRACT Several evidences indicate that Lyman Break Galaxies (LBGs) in the Epoch of Reionization (redshift z > 6) might host massive black holes (MBHs). We address this question by using a merger-tree model combined with tight constraints from the 7 Ms Chandra survey and the known high-z super-MBH population. We find that a typical LBG with MUV = −22 residing in an Mh ≈ 1012 M⊙ halo at z = 6 host an MBH with mass M• ≈ 2 × 108 M⊙. Depending on the fraction, fseed, of early haloes planted with a direct collapse black hole seed (Mseed = 105M⊙), the model suggests two possible scenarios: (i) if fseed = 1, MBHs in LBGs mostly grow by merging and must accrete at a low (λE ≃ 10−3) Eddington ratio not to exceed the experimental X-ray luminosity upper bound $L_\mathrm{ X}^* = 10^{42.5} {\rm erg\, s}^{-1}$; (ii) if fseed = 0.05, accretion dominates (λE ≃ 0.22) and MBH emission in LBGs must be heavily obscured. In both scenarios the UV luminosity function is largely dominated by stellar emission up to very bright mag, $M_{\rm UV} \lower.5ex\hbox{$\,\, \buildrel\gt \over \sim \,\,$}-23$, with BH emission playing a subdominant role. Scenario (i) poses extremely challenging, and possibly unphysical, requirements on DCBH formation. Scenario (ii) entails testable implications on the physical properties of LBGs involving the FIR luminosity, emission lines, and the presence of outflows.

Characterizing [C ii] Line Emission in Massive Star-forming Clumps

Abstract Because the 157.74 μm [C ii] line is the dominant coolant of star-forming regions, it is often used to infer the global star formation rates of galaxies. By characterizing the [C ii] and far-infrared emission from nearby Galactic star-forming molecular clumps, it is possible to determine whether extragalactic [C ii] emission arises from a large ensemble of such clumps, and whether [C ii] is indeed a robust indicator of global star formation. We describe [C ii] and far-infrared observations using the FIFI-LS instrument on the Stratospheric Observatory For Infrared Astronomy (SOFIA) airborne observatory toward four dense, high-mass, Milky Way clumps. Despite similar far-infrared luminosities, the [C ii] to far-infrared luminosity ratio, /L FIR, varies by a factor of at least 140 among these four clumps. In particular, for AGAL313.576+0.324, no [C ii] line emission is detected despite a FIR luminosity of 24,000 . AGAL313.576+0.324 lies a factor of more than 100 below the empirical correlation curve between /L FIR and found for galaxies. AGAL313.576+0.324 may be in an early evolutionary “protostellar” phase with insufficient ultraviolet flux to ionize carbon, or in a deeply embedded “‘hypercompact” region phase where dust attenuation of UV flux limits the region of ionized carbon to undetectably small volumes. Alternatively, its apparent lack of [C ii] emission may arise from deep absorption of the [C ii] line against the 158 μm continuum, or self-absorption of brighter line emission by foreground material, which might cancel or diminish any emission within the FIFI-LS instrument’s broad spectral resolution element ( km s−1).

The AGN contribution to the UV–FIR luminosities of interacting galaxies and its role in identifying the main sequence

ABSTRACT Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact effects of its influence are still imperfectly understood. To assess the impact of AGNs on interacting systems, we present a spectral energy distribution (SED) analysis of a sample of 189 nearby galaxies. We gather and systematically re-reduce archival broad-band imaging mosaics from the ultraviolet to the far-infrared using data from GALEX, SDSS, 2MASS, IRAS, WISE, Spitzer, and Herschel. We use spectroscopy from Spitzer/IRS to obtain fluxes from fine-structure lines that trace star formation and AGN activity. Utilizing the SED modelling and fitting tool cigale, we derive the physical conditions of the interstellar medium, both in star-forming regions and in nuclear regions dominated by the AGN in these galaxies. We investigate how the star formation rates (SFRs) and the fractional AGN contributions (fAGN) depend on stellar mass, galaxy type, and merger stage. We find that luminous galaxies more massive than about $10^{10} \,\rm {M}_{*}$ are likely to deviate significantly from the conventional galaxy main-sequence relation. Interestingly, infrared AGN luminosity and stellar mass in this set of objects are much tighter than SFR and stellar mass. We find that buried AGNs may occupy a locus between bright starbursts and pure AGNs in the fAGN–[Ne v]/[Ne ii] plane. We identify a modest correlation between fAGN and mergers in their later stages.

The ALPINE−ALMA [C ii] Survey: on the nature of an extremely obscured serendipitous galaxy

ABSTRACT We report the serendipitous discovery of a dust-obscured galaxy observed as part of the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [C ii] at Early times (ALPINE). While this galaxy is detected both in line and continuum emissions in ALMA Band 7, it is completely dark in the observed optical/near-infrared bands and only shows a significant detection in the UltraVISTA Ks band. We discuss the nature of the observed ALMA line, that is [C ii] at $z$ ∼ 4.6 or high-J CO transitions at $z$ ∼ 2.2. In the first case, we find a [C ii]/FIR luminosity ratio of $\mathrm{log}{(L_{[\mathrm{ C}\, \rm {\small {II}}]}/L_{\mathrm{ FIR}})} \sim -2.5$, consistent with the average value for local star-forming galaxies (SFGs). In the second case instead, the source would lie at larger CO luminosities than those expected for local SFGs and high-z submillimetre galaxies. At both redshifts, we derive the star formation rate (SFR) from the ALMA continuum and the physical parameters of the galaxy, such as the stellar mass (M*), by fitting its spectral energy distribution. Exploiting the results of this work, we believe that our source is a ‘main-sequence’, dusty SFG at $z$ = 4.6 (i.e. [C ii] emitter) with $\mathrm{log(SFR/M_{\odot }\, yr^{-1})}\sim 1.4$ and log(M*/M⊙) ∼ 9.9. As a support to this scenario our galaxy, if at this redshift, lies in a massive protocluster recently discovered at $z$ ∼ 4.57, at only ∼1 proper Mpc from its centre. This work underlines the crucial role of the ALPINE survey in making a census of this class of objects, in order to unveil their contribution to the global SFR density at the end of the Reionization epoch.

Constraints on high-J CO emission lines in z ∼ 6 quasars

Abstract We present Atacama Large Millimiter/submillimiter Array (ALMA) observations of eight highly excited CO (${\rm J_{\rm up}}$ >8) lines and continuum emission in two z ∼ 6 quasars: SDSS J231038.88+185519.7 (hereafter J2310), for which CO(8-7), CO(9-8), and CO(17-16) lines have been observed, and ULAS J131911.29+095951.4 (J1319), observed in the CO(14-13), CO(17-16) and CO(19-18) lines. The continuum emission of both quasars arises from a compact region (<0.9 kpc). By assuming a modified black-body law, we estimate dust masses of Log(Mdust/M⊙) = 8.75 ± 0.07 and Log(Mdust/M⊙) = 8.8 ± 0.2 and dust temperatures of Tdust = 76 ± 3 K and $T_{\rm dust}=66^{+15}_{-10}~{\rm K}$, respectively for J2310 and J1319. Only CO(8-7) and CO(9-8) in J2310 are detected, while 3σ upper limits on luminosities are reported for the other lines of both quasars. The CO line luminosities and upper limits measured in J2310 and J1319 are consistent with those observed in local AGN and starburst galaxies, and other z ∼ 6 quasars, except for SDSS J1148+5251 (J1148), the only quasar at z = 6.4 with a previous CO(17-16) line detection. By computing the CO SLEDs normalised to the CO(6-5) line and FIR luminosities for J2310, J1319, and J1149, we conclude that different gas heating mechanisms (X-ray radiation and/or shocks) may explain the different CO luminosities observed in these z ∼ 6 quasar. Future ${\rm J_{\rm up}}$ >8 CO observations will be crucial to understand the processes responsible for molecular gas excitation in luminous high-z quasars.

A Search for High-mass Protostellar Objects in Cold IRAS Sources

Abstract We present the results of CS J = 2 → 1 mapping observations toward 39 massive star-forming regions selected from the previous CO line survey of cold IRAS sources with high-velocity CO flows along the Galactic plane. All sources are detected in CS J = 2 → 1, showing the existence of CS clumps around the IRAS sources. However, one-third of the sources are not deeply embedded in the dense clumps by comparison of the central powering IRAS sources and the morphologies of CS clumps. Physical parameters of the dense molecular clumps are presented. We have identified 12 high-mass protostellar object (HMPO) candidates by checking the association between the dense cores and the IRAS sources, the detection of water maser, and the radio properties toward the IRAS sources. We find that the HMPO sources are characterized by low FIR luminosity to virial mass ratios since they are in very early evolutionary stages when the massive protostars have not reached their full luminosities, which are typical for zero-age main-sequence stars. Large turbulent motion in the HMPO sources may be largely due to the large kinetic energy ejected by the central protostars formed in the dense clumps. However, alternative means or undetected outflows may also be responsible for the turbulence in the clumps.

The bivariate luminosity and mass functions of the local HRS galaxy sample

Aims.We discuss the results of the relationships between theK-band and stellar mass, FIR luminosities, star formation rate, and the masses of the dust and gas of nearby galaxies computing the bivariateK-band-luminosity function (BLF) and bivariateK-band-mass function (BMF) of theHerschelReference Survey (HRS), a volume-limited sample with full wavelength coverage.Methods.We derive the BLFs and BMFs from theK-band and stellar mass, FIR luminosities, star formation rate, dust and gas masses cumulative distributions using a copula method, which is outlined in detail. The use of the computed bivariate taking into account the upper limits allows us to derive a more solid statistical ground for the relationship between the observed physical quantities.Results.The analysis shows that the behaviour of the morphological (optically selected) subsamples is quite different. A statistically meaningful result can be obtained over the whole HRS sample only from the relationship between theK-band and the stellar mass, while for the remaining physical quantities (dust and gas masses, far-infrared luminosity, and star formation rate), the analysis is distinct for late-type (LT) and early-type galaxies (ETG). However, the number of ETGs is small to perform a robust statistical analysis, and in most of the case results are discussed only for the LTG subsample. The luminosity and mass functions (LFs, MFs) of LTGs are generally dependent on theK-band and the various dependencies are discussed in detail. We are able to derive the corresponding LFs and MFs and compare them with those computed with other samples. Our statistical analysis allows us to characterise the HRS which, although non-homogeneously selected and partially biased towards low IR luminosities, may be considered as representative of the local LT galaxy population.

Probing Early Phases of High Mass Stars with 6.7 GHz Methanol Masers

AbstractMethanol masers at 6.7 GHz are the brightest of class II methanol masers and have been found exclusively towards massive star forming regions. These masers can thus be used as a unique tool to probe the early phases of massive star formation. We present here the SED studies of 284 methanol masers chosen from the MMB catalogue, which falls in the Hi-GAL range (|l| ≤ 60°, |b| ≤ 1°). The masers are studied using the ATLASGAL, MIPSGAL and Hi-GAL data at wavelengths ranging from 24−870 micrometers. A single grey body component fit was used to model the cold dust emission whereas the emission from the warm dust is modelled by a black body. The clump properties such as isothermal mass, FIR luminosity and MIR luminosity were obtained using the best fit parameters of the SED fits. We discuss the physical properties of the sources and explore the evolutionary stages of the sources having 6.7 GHz maser emission in the timeline of high mass star formation.

The Dependence of the IR–Radio Correlation on the Metallicity

Abstract We have compiled a sample of 26 metal-poor galaxies with 12 + log(O/H) < 8.1 with both infrared continuum and 1.4 GHz radio continuum data. By comparing to galaxies at higher metallicity, we have investigated the IR–radio relationship’s dependence on metallicity at the 24, 70, 100, and 160 μm bands, as well as the integrated FIR luminosity. It is found that metal-poor galaxies have on average lower than metal-rich ones, with larger offsets at longer IR wavelengths, from −0.06 dex in to −0.6 dex in . The of all galaxies as a whole at 160 μm show positive trends with the metallicity and IR-to-FUV ratio and negative trends with the IR color, while those at lower IR wavelengths show weaker correlations. We propose a mechanism that invokes the combined effects of low obscured-SFR-to-total-SFR fraction and warm dust temperature at low metallicity to interpret the above behavior of , with the former reducing the IR radiation and the latter further reducing the IR emission at longer IR wavelengths. Other mechanisms that are related to the radio emission, including the enhanced magnetic field strength and increased thermal radio contribution, are unable to reconcile the IR-wavelength-dependent differences of between metal-poor and metal-rich galaxies. In contrast to , the mean total-SFR-to-radio ratio of metal-poor galaxies is the same as that for metal-rich galaxies, indicating the 1.4 GHz radio emission is still an effective tracer of SFRs at low metallicity.

ALMA [N ii] 205 μm Imaging Spectroscopy of the Interacting Galaxy System BRI 1202-0725 at Redshift 4.7*

Abstract We present the results from Atacama Large Millimeter/submillimeter Array imaging in the [N ii] 205μm fine-structure line (hereafter [N ii]) and the underlying continuum of BRI 1202-0725, an interacting galaxy system at z = 4.7, consisting of a quasi-stellar object (QSO), a submillimeter galaxy (SMG), and two Lyα emitters, all within ∼25 kpc of the QSO. We detect the QSO and SMG in both [N ii] and continuum. At the ∼1″ (or 6.6 kpc) resolution, both the QSO and SMG are resolved in [N ii], with the de-convolved major axes of ∼9 and ∼14 kpc, respectively. In contrast, their continuum emissions are much more compact and unresolved even at an enhanced resolution of ∼0.″7. The ratio of the [N ii] flux to the existing CO(7−6) flux is used to constrain the dust temperature (T dust) for a more accurate determination of the FIR luminosity L FIR. Our best estimated T dust equals 43 (±2) K for both galaxies (assuming an emissivity index β = 1.8). The resulting L CO(7−6)/L FIR ratios are statistically consistent with that of local luminous infrared galaxies, confirming that L CO(7−6) traces the star formation (SF) rate (SFR) in these galaxies. We estimate that the ongoing SF of the QSO (SMG) has an SFR of 5.1 (6.9) × 103 M ⊙ yr−1 (±30%) assuming Chabrier initial mass function, takes place within a diameter (at half maximum) of 1.3 (1.5) kpc, and will consume the existing 5 (5) × 1011 M ⊙ of molecular gas in 10 (7) × 107 years.

PROBING THE INTERSTELLAR MEDIUM AND STAR FORMATION OF THE MOST LUMINOUS QUASAR AT z = 6.3

ABSTRACT We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the ultraluminous quasar SDSS J010013.02+280225.8 (hereafter, J0100+2802) at z = 6.3, which hosts the most massive supermassive black hole (SMBH), , that is known at z > 6. We detect the [C ii] 158 μm fine structure line and molecular CO(6-5) line and continuum emission at 353, 260, and 3 GHz from this quasar. The CO(2-1) line and the underlying continuum at 32 GHz are also marginally detected. The [C ii] and CO detections suggest active star formation and highly excited molecular gas in the quasar host galaxy. The redshift determined with the [C ii] and CO lines shows a velocity offset of from that measured with the quasar Mg ii line. The CO (2-1) line luminosity provides a direct constraint on the molecular gas mass, which is about . We estimate the FIR luminosity to be , and the UV-to-FIR spectral energy distribution of J0100+2802 is consistent with the templates of the local optically luminous quasars. The derived [C ii]-to-FIR luminosity ratio of J0100+2802 is 0.0010 ± 0.0002, which is slightly higher than the values of the most FIR luminous quasars at z ∼ 6. We investigate the constraint on the host galaxy dynamical mass of J0100+2802 based on the [C ii] line spectrum. It is likely that this ultraluminous quasar lies above the local SMBH–galaxy mass relationship, unless we are viewing the system at a small inclination angle.

Total infrared luminosity estimation from local galaxies in AKARI all sky survey

We aim to use the a new and improved version of AKARI all sky survey catalogue of far-infrared sources to recalibrate the formula to derive the total infrared luminosity. We cross-match the faint source catalogue (FSC) of IRAS with the new AKARI-FIS and obtained a sample of 2430 objects. Then we calculate the total infrared (TIR) luminosity $L_{\textrm{TIR}}$ from the Sanders at al. (1996) formula and compare it with total infrared luminosity from AKARI FIS bands to obtain new coefficients for the general relation to convert FIR luminosity from AKARI bands to the TIR luminosity.

HIGH- J CO VERSUS FAR-INFRARED RELATIONS IN NORMAL AND STARBURST GALAXIES

We present correlations between 9 CO transition ($J=4-3$ to $12-11$) and beam-matched far-infrared (Far-IR) luminosities ($L_{\mathrm{FIR},\,b}$) among 167 local galaxies, using {\it{Herschel}} Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (SPIRE; FTS) spectroscopic data and Photoconductor Array Camera and Spectrometer (PACS) photometry data. We adopt entire-galaxy FIR luminosities ($L_{\mathrm{FIR},\,e}$) from the {\it{IRAS}} Revised Bright Galaxy Sample and correct to $L_{\mathrm{FIR},\,b}$ using PACS images to match the varying FTS beam sizes. All 9 correlations between $L'_{\mathrm{CO}}$ and $L_{\mathrm{FIR},\,b}$ are essentially linear and tight ($\sigma$=0.2-0.3 dex dispersion), even for the highest transition, $J=12-11$. This supports the notion that the star formation rate (SFR) is linearly correlated with the dense molecular gas ($n_{\mathrm{H}_2}\gtrsim10^{4-6}\,cm^{-3}$). We divide the entire sample into three subsamples and find that smaller sample sizes can induce large differences in the correlation slopes. We also derive an average CO spectral line energy distribution (SLED) for the entire sample and discuss the implied average molecular gas properties for these local galaxies. We further extend our sample to high-{\it{z}} galaxies with CO $J=5-4$ data from the literature as an example, including submillimeter galaxies (SMGs) and "normal" star-forming BzKs. BzKs have similar FIR/CO(5-4) ratios as that of local galaxies, an follow well the locally-determined correlation, whereas SMG ratios fall around or slightly above the local correlation with large uncertainties. Finally, by including Galactic CO($J=10-9$) data as well as very limited high-{\it{z}} CO $J=10-9$ data, we verify that the CO(10-9) -- FIR correlation successfully extends to Galactic young stellar objects, suggesting that linear correlations are valid over 15 orders of magnitude.

AN EXTREME STARBURST IN THE CORE OF A RICH GALAXY CLUSTER ATz= 1.7

We have discovered an optically rich galaxy cluster at z = 1.7089 with star formation occurring in close proximity to the central galaxy. The system, SpARCS104922.6+564032.5, was detected within the Spitzer Adaptation of the red-sequence Cluster Survey, and confirmed through Keck-MOSFIRE spectroscopy. The rest-frame optical richness of Ngal (500 kpc) = 30 ± 8 implies a total halo mass, within 500 kpc, of ∼3.8 ± 1.2 × 1014 M⊙, comparable to other clusters at or above this redshift. There is a wealth of ancillary data available, including Canada–France–Hawaii Telescope optical, UKIRT-K, Spitzer-IRAC/MIPS, and Herschel-SPIRE. This work adds submillimeter imaging with the SCUBA2 camera on the James Clerk Maxwell Telescope and near-infrared imaging with the Hubble Space Telescope. The mid/far-infrared (M/FIR) data detect an Ultra-luminous Infrared Galaxy spatially coincident with the central galaxy, with LIR = 6.2 ± 0.9 × 1012 L⊙. The detection of polycyclic aromatic hydrocarbons at z = 1.7 in a Spitzer-IRS spectrum of the source implies the FIR luminosity is dominated by star formation (an Active Galactic Nucleus contribution of 20%) with a rate of ∼860 ± 130 M⊙ yr−1. The optical source corresponding to the IR emission is likely a chain of >10 individual clumps arranged as "beads on a string" over a linear scale of 66 kpc. Its morphology and proximity to the Brightest Cluster Galaxy (BCG) imply a gas-rich interaction at the center of the cluster triggered the star formation. This system indicates that wet mergers may be an important process in forming the stellar mass of BCGs at early times.

Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers

We present fluxes in both neutral carbon [CI] lines at the centers of 76 galaxies with FIR luminosities between 10^{9} and 10^{12} L(o) obtained with Herschel-SPIRE and with ground-based facilities, along with the J=7-6, J=4-3, J=2-1 12CO and J=2-1 13CO line fluxes. We investigate whether these lines can be used to characterize the molecular ISM of the parent galaxies in simple ways and how the molecular gas properties define the model results. In most starburst galaxies, the [CI]/13CO flux ratio is much higher than in Galactic star-forming regions, and it is correlated to the total FIR luminosity. The [CI](1-0)/CO(4-3), the [CI](2-1) (2-1)/CO(7-6), and the [CI] (2-1)/(1-0) flux ratios are also correlated, and trace the excitation of the molecular gas. In the most luminous infrared galaxies (LIRGs), the ISM is fully dominated by dense and moderately warm gas clouds that appear to have low [C]/[CO] and [13CO]/[12CO] abundances. In less luminous galaxies, emission from gas clouds at lower densities becomes progressively more important, and a multiple-phase analysis is required to determine consistent physical characteristics. Neither the CO nor the [CI] velocity-integrated line fluxes are good predictors of H2 column densities in individual galaxies, and X(CI) conversion factors are not superior to X(CO) factors. The methods and diagnostic diagrams outlined in this paper also provide a new and relatively straightforward means of deriving the physical characteristics of molecular gas in high-redshift galaxies up to z=5, which are otherwise hard to determine.

THE HOST GALAXIES OF X-RAY QUASARS ARE NOT STRONG STAR FORMERS

We use ultradeep SCUBA-2 850um observations (~0.37 mJy rms) of the 2 Ms Chandra Deep Field-North (CDF-N) and 4 Ms Chandra Deep Field-South (CDF-S) X-ray fields to examine the amount of dusty star formation taking place in the host galaxies of high-redshift X-ray AGNs. Supplementing with COSMOS, we measure the submillimeter fluxes of the 4-8 keV sources at z>1, finding little flux at the highest X-ray luminosities but significant flux at intermediate luminosities. We determine gray body and MIR luminosities by fitting spectral energy distributions to each X-ray source and to each radio source in an ultradeep Karl G. Jansky Very Large Array (VLA) 1.4 GHz (11.5uJy at 5-sigma) image of the CDF-N. We confirm the FIR-radio and MIR-radio correlations to z=4 using the non-X-ray detected radio sources. Both correlations are also obeyed by the X-ray less luminous AGNs but not by the X-ray quasars. We interpret the low FIR luminosities relative to the MIR for the X-ray quasars as being due to a lack of star formation, while the MIR stays high due to the AGN contribution. We find that the FIR luminosity distributions are highly skewed and the means are dominated by a small number of high-luminosity galaxies. Thus, stacking or averaging analyses will overestimate the level of star formation taking place in the bulk of the X-ray sample. We conclude that most of the host galaxies of X-ray quasars are not strong star formers, perhaps because their star formation is suppressed by AGN feedback.

The host galaxies of X-ray selected active galactic nuclei toz= 2.5: Structure, star formation, and their relationships from CANDELS andHerschel/PACS

We study the relationship between the structure and star-formation rate (SFR) of X-ray selected low and moderate luminosity active galactic nuclei (AGNs) in the two Chandra Deep Fields, using Hubble Space Telescope imaging from the Cosmic Assembly Near Infrared Extragalactic Legacy Survey (CANDELS) and deep far-infrared maps from the PEP+GOODS-Herschel survey. We derive detailed distributions of structural parameters and FIR luminosities from carefully constructed control samples of galaxies, which we then compare to those of the AGNs. At z~1, AGNs show slightly diskier light profiles than massive inactive (non-AGN) galaxies, as well as modestly higher levels of gross galaxy disturbance (as measured by visual signatures of interactions and clumpy structure). In contrast, at z~2, AGNs show similar levels of galaxy disturbance as inactive galaxies, but display a red central light enhancement, which may arise due to a more pronounced bulge in AGN hosts or due to extinguished nuclear light. We undertake a number of tests of these alternatives, but our results do not strongly favour one interpretation over the other. The mean SFR and its distribution among AGNs and inactive galaxies are similar at z>1.5. At z<1, however, clear and significant enhancements are seen in the SFRs of AGNs with bulge-dominated light profiles. These trends suggest an evolution in the relation between nuclear activity and host properties with redshift, towards a minor role for mergers and interactions at z>1.5.

Integral field spectroscopy of nearby QSOs – I. ENLR size–luminosity relation, ongoing star formation and resolved gas-phase metallicities★

[abridged] We present optical integral field spectroscopy for a flux-limited sample of 19 QSOs at z<0.2 and spatially resolve their ionized gas properties at a physical resolution of 2-5kpc. The extended narrow line regions (ENLRs), photoionized by the radiation of AGN, have sizes of up to several kpc and correlate more strongly with the QSO continuum luminosity than with the integrated [OIII] luminosity. We find a relation of the form log(r)~(0.46+-0.04)log(L_5100), reinforcing the picture of an approximately constant ionization parameter for the ionized clouds across the ENLR. Besides the ENLR, we also find gas ionized by young massive stars in more than 50 per cent of the galaxies on kpc scales. In more than half of the sample, the specific star formation rates based on the extinction-corrected Ha luminosity are consistent with those of inactive disc-dominated galaxies, even for some bulge-dominated QSO hosts. Enhanced SFRs of up to 70Msun/yr are rare and always associated with signatures of major mergers. Comparison with the SFR based on the 60+100micron FIR luminosity suggests that the FIR luminosity is systematically contaminated by AGN emission and Ha appears to be a more robust and sensitive tracer for the star formation rate. Evidence for efficient AGN feedback is scarce in our sample, but some of our QSO hosts lack signatures of ongoing star formation leading to a reduced specific SFR with respect to the main sequence of galaxies. Based on 12 QSOs where we can make measurements, we find that on average bulge-dominated QSO host galaxies tend to fall below the mass-metallicity relation compared to their disc-dominated counterparts. While not yet statistically significant for our small sample, this may provide a useful diagnostic for future large surveys if this metal dilution can be shown to be linked to recent or ongoing galaxy interactions.

HerMES: THE REST-FRAME UV EMISSION AND A LENSING MODEL FOR THEz= 6.34 LUMINOUS DUSTY STARBURST GALAXY HFLS3

We discuss the restframe UV emission from the starbursting galaxy HFLS3 at z=6.34, discovered in Herschel/SPIRE data due to its red color in the submm wavelengths from 250-500 um. The apparent inst. SFR of HFLS3 inferred from the total FIR luminosity measured with over 15 photometric data points between 100 to 1000 um is 2900 Msun/yr. Keck/NIRC2 Ks band adaptive optics imaging data showed two potential NIR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z=2.1 while the southern galaxy was assumed to HFLS3's NIR counterpart. New HST/WFC3 and ACS imaging data show both optically bright galaxies are in the foreground at z<6. A new lensing model based on HST data and mm-wave continuum emission yields a magnification of 2.2+/-0.3. The lack of multiple imaging constrains the lensing magnification to be lower than either 2.7 or 3.5 at the 95% confidence level for the two scenarios, which attribute one or two components to HFLS3 in the source plane. Correcting for gravitational lensing, the inst. SFR is 1320 Msun/yr with the 95% confidence lower limit around 830 Msun/yr. Using models for the restframe UV to FIR SED, the ave. SFR over the last 100 Myr is around 660 Msun/yr. The dust and stellar masses of HFLS3 from the same SED models are 3x10^8 Msun and ~5x10^10 Msun, respectively, with large systematic uncertainties on assumptions related to the SED model. With HST/WFC3 images we also find diffuse NIR emission about 0.5" (~3 kpc) SW of HFLS3 that remains undetected in the ACS data. The emission has a photometric redshift consistent with either z~6 or a dusty galaxy template at z~2. If at the same redshift as HFLS3 the detected diffuse emission could be part of the complex merger system that could be triggering the starburst. Alternatively, it could be part of the foreground structure at z~2.1 that is responsible for lensing of HFLS3.

GRAIN PHYSICS AND INFRARED DUST EMISSION IN ACTIVE GALACTIC NUCLEUS ENVIRONMENTS

We study the effects of a detailed dust treatment on the properties and evolution of early-type galaxies containing central black holes, as determined by AGN feedback. We find that during cooling flow episodes, radiation pressure on the dust in and interior to infalling shells of cold gas can greatly impact the amount of gas able to be accreted and therefore the frequency of AGN bursts. However, the overall hydrodynamic evolution of all models, including mass budget, is relatively robust to the assumptions on dust. We find that IR re-emission from hot dust can dominate the bolometric luminosity of the galaxy during the early stages of an AGN burst, reaching values in excess of $10^{46}$ erg/s. The AGN-emitted UV is largely absorbed, but the optical depth in the IR does not exceed unity, so the radiation momentum input never exceeds $L_{\rm BH}/c$. We constrain the viability of our models by comparing the AGN duty cycle, broadband luminosities, dust mass, black hole mass, and other model predictions to current observations. These constraints force us to models wherein the dust to metals ratios are $\simeq 1%$ of the Galactic value, and only models with a dynamic dust to gas ratio are able to produce both quiescent galaxies consistent with observations and high obscured fractions during AGN "on" phases. During AGN outbursts, we predict that a large fraction of the FIR luminosity can be attributed to warm dust emission ($\simeq100$ K) from dense dusty gas within $\leq 1$ kpc reradiating the AGN UV emission.