CCD astrometry of faint compact extragalactic radio
sources. II.

Costa, E.

doi:10.1051/0004-6361:20000063

Cited by 6 publications

(3 citation statements)

References 14 publications

(11 reference statements)

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“…Our three detections meanwhile span 6.2-7.2 mag. We however note the uncertain R-band magnitude available in the literature for PKS 1829−718 (Costa 2001), which could increase this range. If we consider both samples together that have a R − W 1 magnitude between 6-7.5 mag, we have 5 Hi absorption detections out of 12, or a 42 ± 14% detection rate.…”

Section: Discussionmentioning

confidence: 85%

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An ASKAP survey for H i absorption towards dust-obscured quasars

Glowacki

Allison

Moss

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Obscuration of quasars by accreted gas and dust, or dusty intervening galaxies, can cause active galactic nuclei (AGN) to be missed in optically-selected surveys. Radio observations can overcome this dust bias. In particular, radio surveys searching for Hi absorption inform us on how the AGN can impact on the cold neutral gas medium within the host galaxy, or the population of intervening galaxies through the observed line of sight gas kinematics. We present the results of a Hi absorption line survey at 0.4 < z < 1 towards 34 obscured quasars with the Australian SKA Pathfinder (ASKAP) commissioning array. We detect three Hi absorption lines, with one of these systems previously unknown. Through optical follow-up for two sources, we find that in all detections the Hi gas is associated with the AGN, and hence that these AGN are obscured by material within their host galaxies. Most of our sample are compact, and in addition, are either gigahertz peaked spectrum (GPS), or steep spectrum (CSS) sources, both thought to represent young or recently re-triggered radio AGN. The radio spectral energy distribution classifications for our sample agree with galaxy evolution models in which the obscured AGN has only recently become active. Our associated Hi detection rate for GPS and compact SS sources matches those of other surveys towards such sources. We also find shallow and asymmetric Hi absorption features, which agrees with previous findings that the cold neutral medium in compact radio galaxies is typically kinematically disturbed by the AGN.

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Section: Discussionmentioning

confidence: 85%

“…Prior to our observations with ASKAP-BETA, the redshift of PKS 1829−718 was not known. There is no spectroscopic measurement in the literature and only a possible optical identification made at ∼23 mag (Costa 2001). This source was detected in Hi absorption during our observations (Section 4).…”

Section: Follow-up Optical Spectroscopy Of Pks 1829−718mentioning

confidence: 84%

An ASKAP survey for H i absorption towards dust-obscured quasars

Glowacki

Allison

Moss

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Following unsuccessful attempts by di and Costa (2001), we have now identified the bright radio source B0008-421 with an R=24.3, somewhat diffuse galaxy (Figure 4). This magnitude is consistent with previous non-detections (which had detection limits down to magnitude 23).…”

Section: B0008-421mentioning

confidence: 96%

GPS radio sources: new optical observations and an updated master list

Labiano

Barthel²,

O’Dea

et al. 2006

A&A

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Aims. We identify optical counterparts, address uncertain identifications and measure previously unknown redshifts of the host galaxies of candidate GPS radio sources, and study their stellar populations. Methods. Long slit spectroscopy and deep optical imaging in the B, V and R bands, obtained with the Very Large Telescope. Results. We obtain new redshifts for B0316+161, B0407-658, B0904+039, B1433-040, and identify the optical counterparts of B0008-421 and B0742+103. We confirm the previous identification for B0316+161, B0407-658, B0554-026, and B0904+039, and find that the previous identification for B0914+114 is incorrect. Using updated published radio spectral information, we classify as non GPS the following sources: B0407-658, B0437-454, B1648+015. The optical colors of typical GPS sources are consistent with single instantaneous burst stellar population models but do not yield useful information on age or metallicity. A new master list of GPS sources is presented.

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Optical monitoring of extragalactic sources for linking the ICRF and the futureGaiacelestial reference frame

Taris

Andrei

Klotz

et al. 2013

A&A

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Context. The astrometric mission Gaia of the European Space Agency is scheduled to be launched in 2013. It will provide an astrometric catalog of 500 000 extragalactic sources that could be the basis of a new optical reference frame after the Hipparcos satellite one. On the other hand, the current International Celestial Reference Frame (ICRF) is based on observations of extragalactic sources at radio wavelength. The astrometric coordinates of sources in these two reference systems will have roughly the same uncertainty. It is then mandatory to observe a set of common targets at both optical and radio wavelengths to link the ICRF with what could be called the Gaia Celestial Reference Frame (GCRF). Aims. The goal of this work is to observe a first set of 70 extragalactic sources at optical wavelengths that could achieve the link with the ICRF. Variations in the light curves of these targets are connected with astrophysical processes that could produce displacements of the optical photocenter. Such displacements, if they exist, are critical in the framework of the link of reference systems. Methods. Four telescopes were used to observe the targets at optical wavelengths. Two of them are located in France, one in Chile, and the last one in Australia. First observations were carried out during one year and a half in the R and V bands. A new method of characterizing the compactness of the targets was applied to the images obtained.Results. This paper presents results for the optical monitoring of extragalactic sources suitable for linking reference systems. We show that a large number of targets in our set are variable at the two observational wavelengths. A short presentation of each object is given, along with some references to earlier photometric studies. A morphological index is defined and applied to the 5000 images obtained during the observation campaign. Conclusions. This work fits into a more general project of astrophotometric and astrophysical studies of extragalactic radiosources in the framework of the reference systems. It brings to the astrometric community some information at optical wavelengths about a set of targets that could be used for the link between the radio ICRF and the future GCRF.

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CCD astrometry of faint compact extragalactic radio sources. II.

Cited by 6 publications

References 14 publications

An ASKAP survey for H i absorption towards dust-obscured quasars

An ASKAP survey for H i absorption towards dust-obscured quasars

GPS radio sources: new optical observations and an updated master list

Optical monitoring of extragalactic sources for linking the ICRF and the futureGaiacelestial reference frame

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