QSO Host Galaxies Research Articles

The Host Galaxy of the Broad Absorption Line QSO PG 1700+518 and Its Ring Galaxy Companion: NICMOS 1.6 Micron Imaging

The 1.6 μm Near Infrared Camera and Multiobject Spectrometer image of the broad absorption line QSO PG 1700+518 clearly resolves the QSO host galaxy and a ringlike companion. The companion is most likely a ring galaxy produced in a collision with the QSO galaxy ~5×10^7 yr ago. The morphology of the PG 1700+518 system is very similar to IRAS 04505-2958 (Boyce et al. 1996). Both objects were identified in a sample of eight QSOs selected by warm far-IR colors and extreme IR luminosities (Low et al. 1988). All eight QSOs show signs of strong interaction, and the presence of two head-on colliding systems in this sample may suggest that small impact parameters favor the energizing of IR-luminous QSOs.

Molecular Gas and Star Formation in the Host Galaxy of the QSO I Zw 1

We have investigated the ISM of the I Zw 1 QSO host galaxy with Plateau de Bure mm-interferometry and high angular resolution near-infrared imaging spectroscopy. We have detected a circumnuclear gas ring of diameter ~ 1.5'' (1.8 kpc) in its millimetric CO line emission and have mapped the disk and the spiral arms of the host galaxy in the ^{12}CO(1-0) line at 115 GHz as well as in the H (1.65 um) and K (2.2 um) band . Combining our new mm- and NIR-data with available estimates of the radio- and far-infrared contributions to the nuclear emission, we find strong evidence for a nuclear starburst ring. A comparison to other sources with nuclear activity indicates that these rings may be a common phenomenon and contribute a large fraction of the central luminosity.

The Nature and Origin ofza≈zeAbsorption Lines in the Redshift 0.20 Quasar, PKS 2135−147

We use new UV and optical spectra and an archival Hubble Space Telescope Wide Field Planetary Camera 2 (HST-WFPC2) image to study the za ? ze absorber in the ze ? 0.20 QSO PKS 2135-147. The UV spectra, obtained with the Faint Object Spectrograph on HST, show strong za ? ze absorption lines of C IV, N V, O VI, Ly?, and Ly?. The za ? ze line profiles are resolved, with deconvolved FWHM of 270-450 km s-1. The Lyman decrement and the O VI and N V doublet ratios indicate that there are also narrower, optically thick line components, and there is evidence in the C IV and Ly? profiles for two blended components. Lower limits on the total column densities are of order 1015 cm-2 for all ions. The ~2:1 ratio of the C IV doublets suggests that the total C IV column density is near the lower limit. If the absorber is photoionized by the QSO and the derived relative columns in C IV and H I are roughly correct, then the metallicity must be at least solar. The location of the za ? ze absorber remains uncertain. The line redshifts indicate that the clouds have little radial motion (less than ?200 km s-1) with respect to the QSO. This small velocity shift could mean that the absorber is outside of the deep gravitational potential of the QSO and the host-galaxy nucleus. Two ~L* galaxies in a small cluster centered on PKS 2135-147 lie within 36 h-1 kpc projected distance and have redshifts consistent with causing or contributing to the za ? ze lines. The extensive halo of the QSO's host galaxy could also contribute. Calculations show that the QSO is bright enough to photoionize gas up to O VI in the low-density halos of the host and nearby cluster galaxies. Nonetheless, there is indirect evidence for absorption much nearer the QSO, namely (1) the derived high (albeit uncertain) metallicity; (2) the relatively strong N V absorption lines, which might be caused by a higher nitrogen abundance in the metal-rich gas; and (3) strong, lobe-dominated, steep-spectrum radio emission, which is known to correlate with a much higher incidence of (probably intrinsic) za ? ze lines. We propose that the C IV/N V/O VI line ratios can be used as a general diagnostic of intrinsic versus intervening absorption, as long as the line saturation effects are understood.

QSO Host Galaxies at z=2.3

Images are discussed of six QSOs at z=2.3, one QSO-like IRAS source at z=2.3, and one QSO at z=1.1, taken with resolution 0.6 to 0.9 arcsec. Five of the QSOs are radio-quiet. All QSOs except one are just resolved, while the IRAS source has definite structure. In some cases, part of the QSO fuzz appears to be a close companion rather than a concentric host galaxy. The luminosities implied for the hosts or companions are typical of bright galaxies with young hot star populations. Radio-quiet QSOs appear to have host galaxies less luminous by ~2 magnitudes than radio-loud QSOs.

The Buried QSO in IRAS F15307+3252 and the Nature of Hyperluminous Infrared Galaxies

We detect a highly polarized continuum and broad emission line spectrum that is typical of QSOs in the hyperluminous infrared galaxy IRAS F15307+3252. The high nonvariable polarization (p = 16%-20%) and the unpolarized narrow emission lines imply that the polarized light is produced by scattering within or near the narrow-line region. Viewed along the vantage point of the scatterers, F15307+3252 would appear to be indistinguishable from luminous optically selected QSOs. The detection of buried QSOs in the three most luminous infrared galaxies known (P09104+4109, F10214+4724, and F15307+3252) suggests that QSO activity is strongly related to the hyperluminous infrared galaxy phenomenon. Even though significant CO emission and the radio-infrared correlation suggest ongoing star formation, these objects do not distinguish themselves dramatically from other QSOs. The high frequency of companions or signs of interaction among the ultra- and hyperluminous infrared galaxies supports the idea that galaxy interaction, accompanied by star formation, is related to the energizing of an active nucleus. If these objects truly represent misdirected QSOs, then hyperluminous infrared galaxies may provide a new view of QSO host galaxies, as well as important clues to the formation and evolution of galaxies and QSOs.

Imaging the host galaxies of high-redshift radio-quiet QSOs

We present new deep K-band and optical images of four radio-quiet QSOs at z approximately = 1 and six radio-quiet QSOs at z approximately = 2.5, as well as optical images only of six more at z approximately = 2.5. We have examined the images carefully for evidence of extended 'fuzz' from any putative QSO host galaxy. None of the z approximately = 2.5 QSOs shows any extended emission, and only two of the z approximately = 1 QSOs show marginal evidence for extended emission. Our 3 sigma detection limits in the K images, m(sub K) approximately = 21 for an isolated source, would correspond approximately to an unevolved L(sup star) elliptical galaxy at z = 2.5 or 2-3 mag fainter than an L(sup star) elliptical at z = 1, although our limits on host galaxy light are weaker than this due to the difficulty of separating galaxy light from QSO light. We simulate simple models of disk and elliptical host galaxies, and find that the marginal emission around the two z approximately = 1 QSOs can be explained by disks or bulges that are approximately 1-2 mag brighter than an unevolved L(sup star) galaxy in one case and approximately 1.5-2.5 mag brighter than L(sub star) in the other. For two other z approximately = 1 QSOs, we have only upper limits (L approximately = L(sup star)). The hosts of the high-redshift sample must be no brighter than about 3 mag above an unevolved L(sup star) galaxy, and are at least 1 magnitude fainter than the hosts of radio-loud QSOs at the same redshift. If the easily detected K-band light surrounding a previous sample of otherwise similar but radio-loud QSOs is starlight, then it must evolve on timescales of greater than or approximately equal to 10(exp 8) yr (e.g., Chambers & Charlot 1990); therefore our non-detection of host galaxy fuzz around radio-quiet QSOs supports the view that high-redshift radio-quiet and radio-loud QSOs inhabit different host objects, rather than being single types of objects that turn their radio emission on and off over short timescales. This is consistent with the general trend at low redshifts that radio-loud QSOs are found in giant elliptical galaxies while radio-quiet QSOs are found in less luminous disk galaxies. It also suggests that the processes responsible for the spectacular properties of radio-loud AGNs at high redshifts might not be generally relevent to the (far more numerous) radio-quiet population.

SYNTHETIC QSO HOST GALAXIES

ABSTRACT The subtraction of a point-spread function (PSF) from QSO images and subsequent deconvolution of the residual is a tool of potential interest for exploring the properties of QSO host galaxies. To test the power of this technique, we synthesize the appearance of QSOs at z=0.3 by combining bright stellar profiles and artificially redshifted images of seven nearby, luminous galaxies with interesting morphology. Such models offer an opportunity to measure how well the profile subtraction method is able to recover the flux and structure of host galaxies. Morphologically, several of our models do resemble real QSOs. In particular, the object created from the image of Arp 243 looks very much like Mrk 1014. Some QSOs have compact galactic companions; these systems appear to be well-represented by our QSO models employing interacting galaxies as hosts. Although, for an assumed seeing FWHM of 1.1", the subtraction and deconvolution method successfully recovers characteristic features of interacting systems, it is unable to recover spiral structure at this redshift. Azimuthally averaged radial brightness profiles of the subtraction residuals usually match the profiles of the original galaxies to within 1.4" of the central pixel. For our assumed parameters, careful application of an objective PSF subtraction procedure can restore an image comprising approximately 90% of a host galaxy's total brightness.

A search for dead quasars among nearby luminous galaxies. I - The stellar kinematics in the nuclei of NGC 2613, NGC 4699, NGC 5746, and NGC 7331

We present observations and analysis of the rotation velocities and velocity dispersions along the major and minor axes of the spiral galaxies NGC 2613, NGC 4699, NGC 5746, and NGC 7331. This work represents the initial results of a project to search for supermassive black holes in the nuclei of nearby galaxies with similar morphological types and luminosities as QSO host galaxies. We analyze the observed stellar kinematics using maximum entropy dynamical models that allow for the possibility of an anisotropic velocity distribution function

HIGH RESOLUTION IMAGING OF QSO 2305+187 (=4C 18.68)

ABSTRACT We present optical imaging of QSO 2305+187 with resolution ranging from 0.1 to 1.0 arcsec, in continuum and line emission. The data are from FOCAM and the HR Cam of the Canada-France-Hawaii telescope, and the Wide Field Camera of the Hubble Space Telescope. These are compared with previously published optical and radio images. The QSO host galaxy has the basic properties of an elliptical, but has significant irregularities, and tidal tails which indicate an ongoing gravitational interaction with a close companion.

Structure in host galaxies of steep-spectrum radio QSOs

We present deep imaging in two bands of five high-luminosity steep-spectrum radio QSOs. The set of broadband filters we have used has been specifically designed to exclude contamination from all strong emission lines found in extended emission regions around QSOs. For four of the objects, we also have deep R-band imaging. Because we generally do not have suitable stars for determining the point-spread function within our limited fields, we have developed a simple technique for detecting asymmetric structure close to the QSO by using a rotational average of the QSO profile itself.

Images and off-nuclear spectroscopy of QSOs

Long-slit spectroscopy is presented of the environs of six QSOs. Data were obtained at 5 A resolution in 1.5-2.0 arcsec seeing with a low-noise CCD detector on the Canada-France-Hawaii telescope. New direct images with 1 arcsec resolution are presented of four objects, one of which is tidally disturbed. The results indicate the presence of old and young stellar populations in QSO host galaxies. Extended line emission is seen in four objects, indicating nonsystematic relative motions of a few hundred km/s. Five of the objects have no radio emission, and these all have strong Fe II nuclear emission lines. 22 refs.

The local environments of low-redshift quasars and powerful radio galaxies

We have studied the local environments (z < 100h^-1^ kpc) of 31 low-redshift (z < 0.3) QSOs and 35 powerful radio galaxies (PRGs---defined to have P_178_ > 10^25^ W Hz^-1^) using V and R CCD frames processed through FOCAS to generate catalogs of companion galaxies. We find that the PRGs and the radio-loud QSOs typically inhabit regions with local galaxy densities similar to normal giant ellipticals and 3-4 times less dense than the regions inhabited by lower power radio-loud elliptical galaxies. The radio-loud QSOs and PRGs have about twice the average number of bright (L > 0.2 L_*_), nearby (r < 100 kpc) companion galaxies (at the 95% confidence level) compared to the radio-quiet QSOs, with the respective averages being about two companions and one companion. The luminosity function of the companions of the radio-loud objects (PRGs and QSOs) is unusually flat at the high end (> 0.2 L_*_) compared to a standard Schechter function (a 99% confidence level difference), while the luminosity function of the companions to the radio-quiet QSOs is consistent with a Schechter function. The brightest companion galaxy is on-average about 2 mag less bright than the QSO host galaxy or PRG (reflecting the large optical luminosities of the QSO hosts and PRGs). Finally, we find no difference between the local environments of radio-loud QSOs and PRGs in terms of galaxy density or the shape of the companion galaxy luminosity function. These results have some interesting implications for theories of the origin of nuclear activity and the relationships between the various classes of active galaxies and QSOs. Radio-quiet and radio-loud QSOs must be intrinsically different populations without any obvious evolutionary connection. This agrees with previously reported differences between the properties of the host galaxies. In contrast, the radio-loud QSOs and PRGs are likely to be closely related objects. They could be related in an evolutionary sense or might differ only in their geometric orientation with respect to the line of sight.

What is the difference between radio-loud and radio-quiet quasi-stellar objects?

Measures of the nuclear and host galaxy luminosities and colors and a morphological discussion of the host galaxies are presented for a sample of low-redshift, high-luminosity, radio-quiet QSOs whose redshift and luminosity distribution matches that of a radio-loud sample previously discussed. Radio-quiet QSOs are found to reside in galaxies which are smaller, fainter, and redder than the host galaxies of radio-loud QSOs. These properties are generally consistent with the suggestion that radio-quiet QSOs are located in spiral-type galaxies and radio-loud QSOs are located in more elliptical-type galaxies. Significantly less evidence is found for tidal interactions among the radio-quiet objects, although they appear to reside in somewhat richer environments in terms of nearby companions.

QSO activity and host galaxy evolution

The question of evacuation of the interstellar medium of the host galaxy of a quasar is examined. Compton heating due to hard X-rays from the quasar is considered. It is shown that the evacuation radius is much smaller than that hitherto believed and that it is redshift dependent. It is also shown that evacuation of the central part of the interstellar medium need not switch off the central engine, the quasar. 34 references.

What is the difference between radio galaxies and radio quasar galaxies?

Deep optical imaging in the B and R band of about 50 luminous radio galaxies and radio QSOs in the redshift range 0.1-0.5 is reported. More than 80 percent of each type of object are optically interacting; about 60 percent are irregular in some way, and about 30 percent have tidal tails. Separations range from a few kpc to tens of kpc. About 30 percent of the objects have elliptical galaxy characteristics and none has spiral. The mean optical absolute magnitude of radio galaxies is fainter by 1 mag than the host galaxies of QSOs, and the distributions differ significantly. Radio galaxies are redder and larger and have smaller luminosity scale lengths than QSO hosts. Thus, they are a different sample of objects. In all objects, however, galaxy size is greatest at M(R) of about -22, and at the lower redshifts. 30 references.

On the nature of QSO host galaxies

view Abstract Citations (198) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Nature of QSO Host Galaxies Smith, E. P. ; Heckman, T. M. ; Bothun, G. D. ; Romanishin, W. ; Balick, B. Abstract Results of an analysis of deep images of 31 low-redshift QSOs and lower luminosity QSO/AGNs obtained with the prime focus CCD system on the CTIO 4 m telescope are presented. The host galaxies of QSOs are generally luminous systems populating the exponential tail of the galaxy luminosity function. Seyfert galaxies are apparently less luminous than the hosts of radio-quiet QSOs. The radio-loud QSOs are more luminous than the radio-quiet QSO hosts. For the sample of QSOs and QSO/AGNs, there is a trend for the radio-loud hosts to be better fitted by elliptical galaxy models and for the radio-quiet hosts to be fitted by disk galaxies, suggesting that the dichotomy known to exist between Seyfert and radio galaxies extends to much higher levels of nuclear luminosity. These results strengthen the empirical basis for a continuity in properties between Seyfert galaxies and radio-quite QSOs and between radio galaxies and radio-loud QSOs. Publication: The Astrophysical Journal Pub Date: July 1986 DOI: 10.1086/164321 Bibcode: 1986ApJ...306...64S Keywords: Galactic Nuclei; Galactic Structure; Image Analysis; Quasars; Active Galactic Nuclei; Astronomical Spectroscopy; Cosmology; Data Processing; Galactic Evolution; Luminosity; Red Shift; Astrophysics; GALAXIES: NUCLEI; GALAXIES: PHOTOMETRY; GALAXIES: STRUCTURE; QUASARS; RADIO SOURCES: GALAXIES full text sources ADS | data products SIMBAD (30) NED (26)

An atlas of QSO luminosity profiles

view Abstract Citations (60) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An atlas of QSO luminosity profiles. Hutchings, J. B. ; Crampton, D. ; Campbell, B. ; Duncan, D. ; Glendenning, B. Abstract Isophotes of optical images in R and B passbands of 77 QSOs of redshift less than 0.7 are presented, supplementing the discussion of the main properties of the QSO nuclei and host galaxies given by Hutchings et al. (1981, 1982, 1984) and Hutchings and Campbell (1983). Maps over areas of about 30 arcsec square and azimuthally averaged log I versus radius plots for the QSOs and point-spread functions are shown. In addition to the QSO morphology, many maps show nearby and interacting companion galaxies. Commentary and numerical details are provided for each object. These data should form the basis for further morphological studies and spectroscopic investigations. Publication: The Astrophysical Journal Supplement Series Pub Date: June 1984 DOI: 10.1086/190958 Bibcode: 1984ApJS...55..319H Keywords: Astronomical Maps; Galactic Radiation; Luminous Intensity; Quasars; Astronomical Photometry; Isophotes; Morphology; Photographic Plates; Point Spread Functions; Astronomy full text sources ADS | data products SIMBAD (74) NED (53)