Host Galaxies Of Quasi-stellar Objects Research Articles

Deep Hubble Space Telescope Imaging on the Extended Lyα Emission of a QSO at z = 2.19 with a Damped Lyman Alpha System as a Natural Coronagraph

Abstract Recent observations suggest that proximate damped Lyα (PDLA) systems can be used to study the host galaxies of quasi-stellar objects (QSOs), because the PDLAs can block the bright point-spread function from central QSOs. Using six orbits of narrowband imaging with Hubble Space Telescope (HST)/WFC3, we present the first high-resolution narrowband image of the Lyα emission in the PDLA trough of the QSO SDSS J115432.67–021537.9. We detect one major component and one minor component in the narrowband imaging. Combining the /WFC3 imaging with deep Magellan/MagE spectra, we measure that the Lyα flux = , which is among the luminous (≈2.7 ) Lyα emitters at 2.19. The -based star formation rate is ∼7 . These observational results favor that the star formation from the host galaxy could be the main mechanism powering the Lyα emission. This new method sheds light on the study of the kinematic structure and the spatial distribution of the extended Lyα emitting regions around the QSO host.

Decomposing the host galaxy from high-z QSOs using principal component analysis

High resolution deep imaging from space and adaptive optics techniques with large ground-based facilities have enabled studies examining faint host galaxies of high redshift quasi-stellar objects (QSOs). However, the related image processing techniques, especially for a precise point-spread function (PSF) reconstruction and characterization of the host galaxy light profiles, have yet to be optimized. We present here the scientific performance of a principal component analysis (PCA) based PSF subtraction of the central bright point source of high redshift QSO images, as well as further characterization of the host galaxy profile by directly fitting a Sèrsic model to the residual image using the Markov Chain Monte Carlo (MCMC) algorithm. With a set of reference PSF star images which represent interleaving exposures between the QSO imaging, we can create an orthogonal basis of eigen-images and restore the PSF of QSO images by projecting the QSO images onto the basis. In this way, we can quantify the modes in which the PSF varies with time by a basis function that characterizes the temporal variations of the reference star as well as the QSO images. To verify the algorithm, we performed a simulation and applied this method to one of the high-z QSO targets from Mechtley et al. We demonstrate that the PCA-based PSF subtraction and further modeling of the galaxy’s light profile using MCMC fitting would sufficiently remove the effects from central dominating point sources, and improve characterization ability for the host galaxies of high-z QSOs to the background noise level which is much better than previous two-component fitting procedures.

A low-luminosity type-1 QSO sample: Insight from integral-field spectroscopy

AbstractThe properties of the host galaxies of quasi-stellar objects (QSOs) are essential for the understanding of the suspected coevolution of central supermassive black holes (BHs) and their host galaxies. In Busch et al. (2014), we present a study of 20 low-luminosity type-1 QSOs (LLQSO; Busch et al.2012) that have been selected from the Hamburg/ESO survey for bright UV-excess QSOs (z ≤ 0.06). Performing careful decomposition of deep near-infrared J,H,K images, we found that the observed sources do not follow published MBH – Lbulge relations for inactive galaxies, supporting similar results found for type-1 AGN in the optical. This can be explained by overluminous bulges with very young stellar populations or undermassive black holes that are observed in a phase of growth. We use 3d-spectroscopy in the optical and near-infrared as a powerful tool to analyze gas and stellar kinematics, determine gas masses, star formation rate, trace underlying stellar continuum, etc. (e.g., Smajić et al.2014) and thereby constrain possible evolution scenarios. The results will be interpreted in the context of galaxy evolution and particularly the still unknown role of the AGN in this process. Here, we show first results for HE 1029-1831.

A low-luminosity type-1 QSO sample

Recognizing the properties of the host galaxies of quasi-stellar objects (QSOs) is essential to understand the suspected coevolution of central supermassive black holes (BHs) and their host galaxies. We selected a subsample of the Hamburg/ESO survey for bright UV-excess QSOs, containing only the 99 nearest QSOs with redshift z<=0.06, that are close enough to allow detailed structural analysis. From this "low-luminosity type-1 QSO sample", we observed 20 galaxies and performed aperture photometry and bulge-disk-bar-AGN-decomposition with BUDDA on near-infrared J, H, K band images. From the photometric decomposition of these 20 objects and visual inspection of images of another 26, we find that ~50% of the hosts are disk galaxies and most of them (86%) are barred. Stellar masses, calculated from parametric models based on inactive galaxy colors, range from 2x10^9 M_sun to 2x10^11 M_sun. Black hole masses measured from single epoch spectroscopy range from 1x10^6 M_sun to 5x10^8 M_sun. In comparison to higher luminosity QSO samples, LLQSOs tend to have lower stellar and BH masses. Also, in the effective radius vs. mean surface-brightness projection of the fundamental plane, they lie in the transition area between luminous QSOs and "normal" galaxies. This can be seen as further evidence that they can be pictured as a "bridge" between the local Seyfert population and luminous QSOs at higher redshift. Eleven low-luminosity QSOs for which we have reliable morphological decompositions and BH mass estimations lie below the published BH mass vs. bulge luminosity relations for inactive galaxies. This could be partially explained by bulges of active galaxies containing much younger stellar populations than bulges of inactive galaxies. Also, one could suspect that their BHs are undermassive. This might hint at the growth of the host spheroid to precede that of the BH.

A search for H2O maser emission in nearby low-luminosity QSO host galaxies

A sample of nearby galaxies hosting low-luminosity type 1 quasi-stellar objects (QSOs), previously studied in CO and HI emission lines, has been searched for maser emission. Using the Effelsberg 100-m telescope, we observed 17 sources with redshifts of z<0.06 and {\delta}>-30{\deg} for emission in the 22 GHz water vapor maser transition. The sample objects have been drawn from a wide-angle survey for optically bright QSOs (Hamburg /ESO survey, HES). No host galaxies from the sample have been detected in the water maser emission line. In this paper we review the discussion on the reasons for water megamasers being rarely found in Seyfert 1 galaxies. Eight of them are bulge dominated and probably of elliptical type (E/S0), whereas 6 have spiral geometry. Three of the objects seem to be in a phase of merging/interaction. We found 3{\sigma} upper limits for the flux density of 27 to 60 mJy at spectral resolutions of ~0.43 km/s. We furthermore find that the viewing angle to the line of sight to the galaxy, under which the probability to detect megamaser emission is highest, is about 6{\deg}.

THE TWO-COMPONENT RADIO LUMINOSITY FUNCTION OF QUASI-STELLAR OBJECTS: STAR FORMATION AND ACTIVE GALACTIC NUCLEUS

Despite decades of study, it remains unclear whether there are distinct radio-loud and radio-quiet populations of quasi-stellar objects (QSOs). Early studies were limited by inhomogeneous QSO samples, inadequate sensitivity to probe the radio-quiet population, and degeneracy between redshift and luminosity for flux-density-limited samples. Our new 6 GHz EVLA observations allow us for the first time to obtain nearly complete (97%) radio detections in a volume-limited color-selected sample of 179 QSOs more luminous than M_i = -23 from the Sloan Digital Sky Survey (SDSS) Data Release Seven in the narrow redshift range 0.2 < z < 0.3. The dramatic improvement in radio continuum sensitivity made possible with the new EVLA allows us, in 35 minutes of integration, to detect sources as faint as 20 microJy, or log[L_6 (W/Hz)] ~ 21.5 at z = 0.25, well below the radio luminosity, log[L_6 (W/Hz)] ~ 22.5, that separates star-forming galaxies from radio-loud active galactic nuclei (AGNs) driven by accretion onto a super-massive black hole. We calculate the radio luminosity function (RLF) for these QSOs using three constraints: (a) EVLA 6 GHz observations for log[L_6 (W/Hz)] < 23.5, (b) NRAO-VLA Sky Survey (NVSS) observations for log[L_6 (W/Hz)] > 23.5, and (c) the total number of SDSS QSOs in our volume-limited sample. We show that the RLF can be explained as a superposition of two populations, dominated by AGNs at the bright end and star formation in the QSO host galaxies at the faint end.

H I in nearby low-luminosity QSO host galaxies

We searched for 21 cm H i emission in a sample of 27 previously CO detected nearby galaxies hosting low-luminosity quasi - stellar objects (QSOs). In this paper we investigate the relationship between the H i and infrared properties of these host galaxies, compare the atomic and molecular gas content and look for connections to the optical and FIR properties. The single dish observations have been made with the Effelsberg 100-m telescope with a beam size of 9.5 � . The sample objects have been drawn from a wide-angle survey for optically bright QSOs (HES), which have declinations δ> −30 ◦ and redshifts up to z = 0.06. 12 host galaxies from the sample have been detected in the H i 21 cm emission line. Eight of them have a spiral geometry, whereas the other four are bulge dominated and probably of elliptical type (E/S0). Three of the objects seem to be in a phase of merging/interaction. The neutral atomic

Host Galaxies of QSOs at z > 5

ABSTRACTThis paper presents J‐band imaging of two quasars with redshifts of 5.02 and 5.17, respectively, using the Gemini North (GN) telescope. The quasars differ in brightness by several magnitudes. The image resolution ranged from 0.″4 to 1.″0. Both of the quasi‐stellar objects (QSOs) have resolved structure in their innermost arcsecond, and the brighter one shows resolved luminosity to a radius of 6″. We also report on GN I‐ and z‐band imaging of two QSOs at a redshift above 6 that are unresolved. The host galaxy luminosities and structure (and upper limits) are discussed and compared with K‐band resolved QSOs at z = 4.7 and the general K‐z relationship.

Submillimetre photometry of X-ray absorbed quasi-stellar objects: their formation and evolutionary status

We present an analysis of the submillimetre/X-ray properties of 19 X-ray absorbed, Compton-thin quasi-stellar objects (QSOs) selected to have luminosities and redshifts that represent the peak of cosmic QSO activity, i.e. ∼L* objects at 1 < z < 3. Of these, we present new data for 11 objects not previously observed at submillimetre wavelengths and additional data for a further three. The detection rate is 42 per cent, much higher than typically reported for samples of QSOs. Detection statistics show (at the 3–4σ level) that this sample of absorbed QSOs has a higher submillimetre output than a matched sample of unabsorbed QSOs. We argue that the far-infrared luminosity is produced by massive star formation. In this case, the correlation found between far-infrared luminosity and redshift can be interpreted as cosmological evolution of the star formation rate in the QSO host galaxies. Because the submillimetre luminous phase is confined to z > 1.5, the high star formation rates are consistent with a scenario in which the QSOs evolve to become local luminous elliptical galaxies. Combining these results with previously published data for X-ray unabsorbed QSOs and submillimetre-selected galaxies, we propose the following evolutionary sequence: the forming galaxy is initially far-infrared luminous but X-ray weak similar to the sources discovered by the Submillimetre Common-User Bolometer Array (SCUBA); as the black hole and spheroid grow with time, a point is reached when the central QSO becomes powerful enough to terminate the star formation and eject the bulk of the fuel supply (the Compton-thin absorbed QSO phase); this transition is followed by a period of unobscured QSO activity, which subsequently declines to leave a quiescent spheroidal galaxy.

Chemical abundances in QSO host galaxies and environments from narrow absorption line systems

We determined C, N and a-element relative abundances in the gas surrounding six quasi-stellar objects (QSOs) at an average redshift of z 2.4, by studying six narrow associated absorption systems in Ultraviolet Visual Echelle Spectrograph (UVES) high-resolution spectra. We found five systems with a metallicity (measured by C/H) consistent or above the solar value. The ionization structure observed in the associated systems is clearly different from that of the intervening ones, indicating that the associated systems are influenced by the strong UV flux from the QSO. There is a possible correlation (anticorrelation) between [N/C] ([Si/C]) and [C/H] of the studied associated systems, and [N/C]= 0 when [C/H]= 0. We have compared these observational results with the predictions of a model simulating the joint evolution of QSOs and their spheroidal hosts. The agreement turns out to be very good; in particular, the case envisaging massive haloes and high star formation rates recovers both the correlation between [N/C] and [C/H] and the anticorrelation for [Si/C] versus [C/H]. Narrow associated absorption systems prove to be powerful tracers of the chemical abundances in gas belonging to high-redshift spheroidal galaxies. The outflow of this same gas, triggered by the QSO feedback, is probably going to contribute to the early enrichment of the surrounding intergalactic medium. A larger sample, possibly increasing the number of ionization stages, chemical elements and the redshift range, would allow us to put firm constraints on detailed chemical evolution models of galaxies at high redshifts.

Hubble Space Telescope Wide Field Planetary Camera 2 observations of hyperluminous infrared galaxies

We present Hubble Space Telescope Wide Field Planetary Camera 2 I-band imaging for a sample of nine hyperluminous infrared galaxies (HLIRGs) spanning a redshift range 0.45 < z < 1.34. Three of the sample have morphologies showing evidence for interactions and six are quasi-stellar objects (QSOs). Host galaxies in the QSOs are detected reliably out to z ∼ 0.8. The detected QSO host galaxies have an elliptical morphology with scalelengths spanning 6.5 < re (kpc) < 88 and absolute k-corrected magnitudes spanning −24.5 < MI < −25.2. There is no clear correlation between the infrared (IR) power source and the optical morphology. None of the sources in the sample, including F15307+3252, shows any evidence for gravitational lensing. We infer that the IR luminosities are thus real. Based on these results, and previous studies of HLIRGs, we conclude that this class of object is broadly consistent with being a simple extrapolation of the ULIRG population to higher luminosities; ULIRGs being mainly violently interacting systems powered by starbursts and/or active galactic nuclei. Only a small number of sources, the infrared luminosities of which exceed 1013 L⊙, are intrinsically less luminous objects that have been boosted by gravitational lensing.