Host galaxies of intermediate redshift radio-loud and radio-quiet quasars

• In a search for host galaxies associated with quasars, the authors present results from deep CCD imaging using the European Southern Observatory 3.5-m New Technology Telescope. Altogether 21 targets, 12 radio-loud and nine radio-quiet quasars, were observed in R, and additional V and Gunn i images were collected for a subgroup of these. The quasar redshifts are between 0.4 and 0.8, a range largely unexplored in previous studies. At these redshifts the R band corresponds to a rest-frame wavelength between 4600 and 3600 Aring. Thus, the authors are primarily probing the light from young stellar components of the presumed host galaxies. To separate out the light originating from the host object the authors remove the quasar contribution by scaling the point spread function (PSF). The PSF is a combination of an empirical PSF model, derived from stars lying in the same field as the quasars (used for the core of the PSF), and an analytical model for the wings of the PSF. After PSF subtraction of the QSO image the authors identify extended residual objects in 17 targets (nine in radio-loud and eight in radio-quiet quasars), of which a few are only marginal detections. These objects are large and luminous and their colours are relatively blue. Their V-R colours are consistent with a stellar population typical of late-type spirals and irregular galaxies. The blue colours could be caused by recent star formation events or by scattering of the QSO light

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

Experimental/ astronomical photometry

galaxies

quasars

red shift/ host galaxies

intermediate redshift radio-loud quasars

intermediate redshift radio-quiet quasars

CCD imaging

R-band images

V-band images

Gunn i-band images

quasar redshift 0.4 to 0.8

young stellar components

point spread function

V-R colours

late-type spirals

irregular galaxies

star formation events

QSO light scattering

360 to 460 nm/ A9850G Radiation and spectra of galaxies A9870J Quasars A9850E Galactic structure

content and morphology A9580J Photographic region astronomical observations/ wavelength 3.6E-07 to 4.6E-07 m

Publikations- och innehållstyp

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