FIRST-based survey of Compact Steep Spectrum sources, V.
  Milliarcsecond-scale morphology of CSS objects
Astronomy & Astrophysics manuscript no. 6364 c© ESO 2021
June 8, 2021
FIRST-based survey of compact steep spectrum sources
V. Milliarcsecond-scale morphology of CSS objects
M. Kunert-Bajraszewska1 and A. Marecki1
Toruń Centre for Astronomy, N. Copernicus University, 87-100 Toruń, Poland
Received 8 September 2006; Accepted 7 March 2007
ABSTRACT
Aims. Multifrequency VLBA observations of the final group of ten objects in a sample of FIRST-based compact steep spectrum
(CSS) sources are presented. The sample was selected to investigate whether objects of this kind could be relics of radio−loud AGNs
switched off at very early stages of their evolution or possibly to indicate intermittent activity.
Methods. Initial observations were made using MERLIN at 5 GHz. The sources have now been observed with the VLBA at 1.7, 5 and
8.4 GHz in a snapshot mode with phase-referencing. The resulting maps are presented along with unpublished 8.4-GHz VLA images
of five sources.
Results. Some of the sources discussed here show a complex radio morphology and therefore a complicated past that, in some cases,
might indicate intermittent activity. One of the sources studied – 1045+352 – is known as a powerful radio and infrared-luminous
broad absorption line (BAL) quasar. It is a young CSS object whose asymmetric two-sided morphology on a scale of several hundred
parsecs, extending in two different directions, may suggest intermittent activity. The young age and compact structure of 1045+352
is consistent with the evolution scenario of BAL quasars. It has also been confirmed that the submillimetre flux of 1045+352 can be
seriously contaminated by synchrotron emission.
Key words. galaxies: active, galaxies: evolution, quasars: absorption lines
1. Introduction
Following early hypotheses (Phillips & Mutel, 1982; Carvalho,
1985) suggesting that the gigahertz-peaked spectrum (GPS)
and compact steep spectrum (CSS) could be young objects,
Readhead et al. (1996) proposed an evolutionary scheme uni-
fying three classes of radio-loud AGNs (RLAGNs): symmet-
ric GPS objects – CSOs (compact symmetric objects); sym-
metric CSS objects – MSOs (medium-sized symmetric objects)
and large symmetric objects (LSOs). In this scheme GPS/CSO
sources with linear sizes less than 1 kpc1 would evolve into
CSS/MSOs with subgalactic sizes (<20 kpc) and these in turn
would eventually become LSOs during their lifetimes. Two
pieces of evidence definitely point towards GPS/CSS sources
being young objects: lobe proper motions (up to 0.3c) giving
kinematic ages as low as ∼103 years for CSOs (Owsianik et al.,
1998; Giroletti et al., 2003; Polatidis & Conway, 2003) and ra-
diative ages typically ∼105 years for MSOs (Murgia et al.,
1999). Although these AGNs are small-scale objects, in some
cases CSO/GPS sources are associated with much larger ra-
dio structures that extend out to many kiloparsecs. In these
cases, it has been suggested that the CSO/GPS stage rep-
resents a period of renewed activity in the life cycle of
the AGN (Stanghellini et al., 2005, and references therein).
Reynolds & Begelman (1997) have also proposed a model in
which extragalactic radio sources are intermittent on timescales
Send offprint requests to: M. Kunert-Bajraszewska
e-mail: magda@astro.uni.torun.pl
1 For consistency with earlier papers in this field, the following
cosmological parameters have been adopted throughout this paper:
H0=100 km s
−1 Mpc−1 and q0=0.5. Throughout this paper, the spectral
index is defined such that S ∝ να.
of ∼104–105 years. Following the above scenarios and also an
earlier suggestion by Readhead et al. (1994) and O’Dea & Baum
(1997) that there exists a large population of compact, short-
lived objects, Marecki et al. (2003, 2006) concluded that the evo-
lutionary track proposed by Readhead et al. (1996) is only one
of many possible tracks. A lack of stable fuelling from the black
hole can inhibit the growth of a radio source, and consequently
it will never reach the LSO stage, at least in a given phase of its
activity.
Observational support for the above ideas has been pro-
vided by Gugliucci et al. (2005). They calculated the kinematic
ages for a sample of CSOs with well-identified hotspots. It ap-
pears that the kinematic age distribution drops sharply above
∼500 years, suggesting that in many CSOs activity may cease
early. It is, therefore, possible that only some of them evolve
any further. Our observations have shown that young, fading
compact sources do indeed exist (Kunert-Bajraszewska et al.,
2005; Marecki et al., 2006; Kunert-Bajraszewska et al., 2006,
hereafter Papers II, III, and IV, respectively). A double source,
0809+404, described in Paper IV is our best example of a very
compact – i.e. very young – fader. The VLBA multifrequency
observations have shown it to have a diffuse, amorphous struc-
ture, devoid of a dominant core and hotspots. Giroletti et al.
(2005) have analysed the properties of a sample of small-size
sources and found a very good example of a kiloparsec-scale
fader (1855+37). It is to be noted that re-ignition of activity in
compact radio sources is not ruled out. In this paper – the fifth
and the last of the series – VLBA observations of 10 CSS and
CSO sources that are potential candidates for compact faders
or objects with intermittent activity are presented. One of these
sources, 1045+352, is of particular interest not only because it
http://arxiv.org/abs/0704.0351v2
2 M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources
has a puzzling radio structure, but it also appears to be a broad
absorption line (BAL) quasar.
As their name somewhat suggests, BAL quasars have very
broad, blue-shifted absorption lines arising from high-ionization
transitions such as C IV, Si IV, N V, etc. (e.g C IV 1549Å). They
constitute ∼10% of the optically selected radio-quiet quasars
with the absorption arising from gas outflow at velocities up to
∼0.2 c (Hewett & Foltz, 2003). In fact, BAL quasars have been
divided into two categories, as 10% of them also show absorp-
tion troughs in low-ionization lines such as Mg II 2800Å. This
group has been designated as LoBAL quasars and the others as
HiBAL ones. The high ionization level and continuous absorp-
tion over a wide velocity range is hard to reconcile with absorp-
tion by individual clouds. Rather, they indicate that BAL regions
exist in both BAL and non-BAL quasars and evidence, accumu-
lated from optically selected BAL quasars, indicates an orienta-
tion hypothesis to explain their nature. It would appear that BAL
quasars are normal quasars seen along a particular line of sight,
e.g. a line of sight skimming the edge of the accretion disk or
torus (Weymann et al., 1991; Elvis, 2000). Murray et al. (1995)
have proposed a model in which the line of sight to a BAL quasar
intersects an outflow or wind that is not entirely radial, e.g. an
outflow that initially emerges perpendicular to the accretion disk
and is then accelerated radially.
For quite a long time it was believed that BAL quasars were
never radio-loud. This view was challenged by Becker et al.
(1997), who discovered the first radio-loud BAL quasar when
using the VLA FIRST survey to select quasar candidates.
Five radio-loud BAL quasars were then identified in NVSS
by Brotherton et al. (1998). Since then, the number of radio-
loud BAL QSOs has increased considerably (Becker et al., 2000;
Menou et al., 2001), following identification of new quasar can-
didates selected from the FIRST survey. Most of the BAL
quasars in the Becker et al. (2000) sample tended to be com-
pact at radio frequencies with either a flat or steep radio spec-
trum. Those with steep spectra could be related to GPS and CSS
sources. A variety of their spectral indices also suggested a wide
range of orientations, contrary to the interpretation favoured
from optically selected quasars. Moreover, Becker et al. (2000)
indicated that the frequency of BAL quasars in their sample was
significantly greater (factor ∼2) than inferred from optically se-
lected samples and that the frequency of BAL quasars appeared
to show a complex dependence on radio loudness.
The radio morphology of BAL quasars is important because
it can indicate inclination in BALs, and therefore yields a di-
rect test of the orientation model. However, information about
the radio structure of BAL quasars is still very limited. Prior
to 2006, only three BAL quasars, FIRST J101614.3+520916
(Gregg et al., 2000), PKS 1004+13 (Wills et al., 1999), and
LBQS 1138−0126 (Brotherton et al., 2002) were known to have
a double-lobed FR II radio morphology on kiloparsec scales,
although this interpretation was doubtful for PKS 1004+13
(Gopal-Krishna & Wiita, 2000). Recently, the population of
FR II-BAL quasars has increased to ten objects (excluding PKS
1004+13) following the discoveries of Gregg et al. (2006) and
Zhou et al. (2006), although some of these still require confir-
mation. Their symmetric structures indicate an “edge-on” ori-
entation, which in turn supports an alternative hypothesis de-
scribed as “unification by time”, with BAL quasars charac-
terised as young or recently refuelled quasars (Becker et al.,
2000; Gregg et al., 2000). There has been only one attempt (at
1.6 GHz with the EVN) to image radio structures of the smallest
(and possibly the youngest) BAL quasars (Jiang & Wang, 2003)
from the Becker et al. (2000) sample. This paper presents high
frequency VLBA images of another very compact BAL quasar
— 1045+352, which makes it the BAL quasar with the best
known radio structure to date.
2. The observations and data reduction
The five papers of this series are concerned with a sample
of 60 candidates selected from the VLA FIRST catalogue
(White et al., 1997)2 which could be weak CSS sources. The
sample selection criteria have been given in Kunert et al. (2002)
(hereafter Paper I). All the sources were initially observed with
MERLIN at 5 GHz and the results of these observations led to
the selection of several groups of objects for further study with
MERLIN and the VLA (Paper II), as well as the VLBA and
the EVN (Papers III and IV). The last of those groups contains
10 sources that, because of their structures (very faint “haloes”
or possible core-jet structures), were not included in the other
groups as they were less likely to be candidates for faders.
However, to complete the investigation of the primary sample,
1.7, 5, and 8.4-GHz VLBA observations of 10 sources listed in
Table 1 together with their basic properties, were carried out on
13 November 2004 in a snapshot mode with phase-referencing.3
Each target source scan was interleaved with a scan on a phase
reference source and the total cycle time (target and phase-
reference) was ∼9 minutes including telescope drive times, with
∼7 minutes actually on the target source per cycle. The cycles
for a given target-calibrator pair were grouped and rotated round
the three frequencies, although the source 1059+351 was only
observed at 1.7 GHz with the VLBA because of its very low flux
density as measured at 5 GHz by MERLIN (13 mJy).
The whole data reduction process was carried out using
standard AIPS procedures but, in addition to this, corrections
for Earth orientation parameter (EOP) errors introduced by the
VLBA correlator also had to be made. For each target source
and at each frequency, the corresponding phase-reference source
was mapped, and the phase errors so determined were applied to
the target sources, which were then mapped using a few cycles
of phase self-calibration and imaging. For some of the sources
a final amplitude self-calibration was also applied. IMAGR was
used to produce the final “naturally weighted”, total intensity im-
ages shown in Figs. 1 to 10. Three of the ten sources (1056+316,
1302+356, 1627+289) were not detected in the 8.4-GHz VLBA
observations, and 1425+287 has not been detected in any VLBA
observations. Flux densities of the principal components of the
sources were measured using the AIPS task JMFIT and are listed
in Table 3.
In addition to the observations described above, unpub-
lished 8.4-GHz VLA observations of five sources – 1056+316,
1126+293, 1425+287, 1627+289, 1302+356 – made in A-conf.
by Glen Langston (first four objects) and Patnaik et al. (1992)
have been included (Figs. 3, 5, 9, 10, and 7, respectively).
It was realised that because of poor u-v coverage at the higher
frequencies, some flux density could be missing and the resul-
tant spectral index maps were not considered to be reliable. Any
calculation of spectral indices from the flux densities quoted in
Table 3 should also be treated only as coarse approximations.
For 1045+352, 30-GHz continuum observations using the
Toruń 32-m radio telescope and a prototype (two-element
2 Official website: http://sundog.stsci.edu
3 Including this paper, the results of the observations of 46 sources
out of 60 candidates from the primary sample have been published. The
observations of 14 objects failed for different reasons.
http://sundog.stsci.edu
M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources 3
Table 1. Basic parameters of target sources
Source RA Dec ID mR z S 1.4 GHz logP1.4GHz S 4.85 GHz α
4.85GHz
1.4GHz LAS LLS
Name h m s ◦ ′ ′′ mJy W Hz−1 mJy ′′ h−1 kpc
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
1045+352 10 48 34.247 34 57 24.99 Q 20.86 1.604 1051 27.65 439 −0.70 ∼0.50 2.1
1049+384 10 52 11.797 38 11 43.83 G 20.76 1.018 712 27.04 205 −1.00 0.14 0.6
1056+316 10 59 43.236 31 24 20.59 G 21.10 0.307∗ 459 25.72 209 −0.63 0.50 1.4
1059+351 11 02 08.686 34 55 10.74 G 19.50 0.594∗ 702 26.52 252 −0.82 3.03 11.5
1126+293 11 29 21.738 29 05 06.40 EF — — 729 — 213 −0.99 0.79 —
1132+374 11 35 05.927 37 08 40.80 G — 2.880 638 28.00 218 −0.86 ∼0.30 1.1
1302+356 13 04 34.477 35 23 33.93 EF — — 483 — 185 −0.77 ∼0.20 —
1407+369 14 09 09.528 36 42 08.06 q 21.51 0.996∗ 538 26.89 216 −0.73 ∼0.25 1.1
1425+287 14 27 40.281 28 33 25.78 EF — — 859 — 198 −1.18 0.75 —
1627+289 16 29 12.290 28 51 34.25 EF — — 526 — 162 −0.95 ∼0.65 —
Description of the columns: (1) source name in the IAU format; (2) source right ascension (J2000) extracted from FIRST; (3) source declination
(J2000) extracted from FIRST; (4) optical identification: G - galaxy, Q - quasar, EF - empty field, q - star-like object, i.e. unconfirmed QSO; (5)
red magnitude extracted from SDSS/DR5; (6) redshift; (7) total flux density at 1.4 GHz extracted from FIRST; (8) log of the radio luminosity
at 1.4 GHz; (9) total flux density at 4.85 GHz extracted from GB6; (10) spectral index between 1.4 and 4.85 GHz calculated using flux densities
in columns (7) and (9); (11) largest angular size (LAS) measured in the 5-GHz MERLIN image – in most cases, as a separation between the
outermost component peaks, otherwise “∼” means measured in the image contour plot; (12) largest linear size (LLS).
∗ photometric redshift extracted from SDSS/DR5
receiver) of the One-Centimeter Receiver Array (OCRA-p,
Lowe et al., 2005) have also been made. The recorded output
from the receiver was the difference between the signals from
two closely-spaced horns effectively separated in azimuth so
that atmospheric variations were mostly cancelled out. The ob-
serving technique was such that the respective two beams were
pointed at the source alternately with a switching cycle of ∼50
seconds for a period of ∼6 minutes, thus measuring the source
flux density relative to the sky background on either side of the
source. The telescope pointing was determined from azimuth
and elevation scans across the point source Mrk 421. The pri-
mary flux density calibrator that was used was the planetary neb-
ula NGC 7027, which has an effective radio angular size of ∼8
arcseconds (Bryce et al., 1997) and for which a correction of the
flux density scale had to be made. However, as NGC 7027 was at
some distance from the target source, the point source 1144+402
was used as a secondary flux density calibrator. Corrections for
the effects of the atmosphere were determined from system tem-
perature measurements at zenith distances of 0◦ and 60◦.
3. Comments on individual sources
1045+352. The MERLIN and VLBA maps (Fig. 1) show this
source to be extended in both the NE/SW and NW/SE directions.
The central compact feature visible in all the maps is probably a
radio core with a steep spectrum. The VLBA image at 1.7 GHz
shows two symmetric protrusions – possibly jets – straddling the
core in a NE/SW direction, the SW emission being weaker than
in the NE. This structure is aligned with the NE/SW emission
visible in the 5-GHz MERLIN image, but the more extended dif-
fuse emission has been resolved out in the VLBA images. The
5-GHz VLBA image shows a core and a one-sided jet pointing
to the East. Some compact features in a NE direction are also
visible. The radio structure in the 8.4-GHz VLBA image is sim-
ilar to that at 5 GHz: an extended radio core and a jet pointing in
an easterly direction.
The observed radio morphology of 1045+352 could indicate
a restart of activity with the NE/SW radio emission being the
first phase of activity, now fading away, and the extension in the
NW/SE direction being a signature of the current active phase.
However, the above is only one of a number of possible interpre-
tations of the structure of 1045+352 – see further discussion in
Sect. 4.
According to Sloan Digital Sky Survey/Data Release 5
(SDSS/DR5), 1045+352 is a galaxy at RA= 10h48m34.s242,
Dec=+34◦57′24.′′95, which is marked with a cross in the
MERLIN map but the spectral observations carried out by
Willott et al. (2002) have shown 1045+352 to be a quasar with
a redshift of z = 1.604. It has been also classified as a HiBAL
object based upon the observed very broad C IV absorption, and
it is a very luminous submillimetre object with detections at both
850µm and 450µm (Willott et al., 2002).
The total flux of 1045+352 at 30 GHz measured by us using
OCRA-p is S 30GHz=69 mJy±7 mJy, which gives a steep spectral
index α = −1.01 between 4.85 GHz and 30 GHz.
1049+384. The 5-GHz MERLIN image (Fig. 2) shows it as
a triple core-jet structure with the brightest component re-
solved into a double structure extended in a NW/SE direc-
tion in the high resolution VLBA observations. The 1.7-GHz
VLBA image shows four radio components (in agreement with
Dallacasa et al., 2002), whereas the 5-GHz and 8.4-GHz VLBA
maps show only three components. However, the 5-GHz VLBA
image published by Orienti et al. (2004) shows all four compo-
nents, and they suggest that the two western components and the
two eastern ones are two independent radio sources. As pointed
by Orienti et al. (2004), it is difficult to classify the object, al-
though the idea that 1049+384 consists of two separate com-
pact, double sources is not very plausible because of the very
small separation, ∼ 0.09′′ (0.4 kpc), between these two poten-
tial objects. Although the spectral index calculations are very
uncertain, it is suggested that one of the eastern components
at RA= 10h52m11.s797, Dec=+38◦11′44.′′027 is a radio core (in
agreement with Orienti et al., 2004) from which jets emerge al-
ternately in opposite directions.
1049+384 is a galaxy with a redshift z = 1.018
(Riley & Warner, 1994), but according to Allington-Smith et al.
(1988) the optical spectrum of 1049+384 shows interme-
diate properties between a galaxy and a quasar. The opti-
4 M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources
1045+352         4994.000 MHz
peak flux density=230.21 mJy/beam, beam size=56 x 41 mas
first contour level=0.12 mJy/beam
RIGHT ASCENSION (J2000)
10 48 34.30 34.28 34.26 34.24 34.22 34.20
34 57 25.8
1045+352         1667.474 MHz
peak flux density=118.71 mJy/beam, beam size=13.1 x 8.2 mas
first contour level=0.80 mJy/beam
RIGHT ASCENSION (J2000)
10 48 34.256 34.254 34.252 34.250 34.248 34.246 34.244 34.242 34.240
34 57 25.14
25.12
25.10
25.08
25.06
25.04
25.02
25.00
24.98
24.96
24.94
1045+352        4987.474 MHz
peak flux density=13.64 mJy/beam, beam size=4.7 x 2.4 mas
first contour level=0.14 mJy/beam
RIGHT ASCENSION (J2000)
10 48 34.254 34.252 34.250 34.248 34.246 34.244
34 57 25.12
25.10
25.08
25.06
25.04
25.02
25.00
24.98
1045+352        8421.474 MHz
peak flux density=4.03 mJy/beam, beam size=2.7 x 1.5 mas
first contour level=0.14 mJy/beam
RIGHT ASCENSION (J2000)
10 48 34.251 34.250 34.249 34.248 34.247 34.246 34.245
34 57 25.08
25.07
25.06
25.05
25.04
25.03
25.02
25.01
Fig. 1. The MERLIN 5-GHz (upper left) and VLBA 1.7, 5, and 8.4-GHz maps of 1045+352. Contours increase by a factor 2, and
the first contour level corresponds to ≈ 3σ. A cross indicates the position of an optical object found using the SDSS/DR5.
cal object was included in SDSS/DR5 (RA= 10h52m11.s802,
Dec=+38◦11′44.′′00) and is marked in all maps with a cross.
1056+316. The 8.4-GHz VLA image (Fig. 3) shows this source
to have a double structure that, in the 5-GHz MERLIN image,
has been resolved into a radio core and probably a hotspot in
a NW radio lobe. Both components are visible in the 1.7-GHz
VLBA image, but neither has been detected in the higher fre-
quency VLBA images. The two weak features on either side of
the NW component in the 1.7-GHz VLBA image may be the
remains of extended emission that has been resolved out.
The optical counterpart of 1056+316 was included
in SDSS/DR5 (RA= 10h59m43.s145, Dec=+31◦24′23.′′31), to-
gether with a photometric redshift (Table 1). Its position is
marked with a cross in 8.4-GHz VLA map.
1059+351. The 5-GHz MERLIN map (Fig. 4) shows a bright
component that is probably a radio core, on almost opposite
sides of which is emission from compact features (hotspots)
within the two radio lobes. This structure agrees with the 1.4-
GHz VLA observations presented by Gregorini et al. (1988) and
Machalski & Condon (1983). Their images clearly show an S-
shaped morphology of 1059+351 with two very diffuse compo-
nents, the brighter one resolved into a double structure in 5-GHz
VLA observations (Machalski, 1998). One of these two com-
ponents is the NW hotspot visible in the 5-GHz MERLIN map,
and the second is probably a radio core visible in both the 5-GHz
MERLIN and 1.7-GHz VLBA images.
The optical counterpart of 1059+351 was included
in SDSS/DR5 (RA= 11h02m08.s727, Dec=+34◦55′08.′′79), to-
gether with a photometric redshift (Table 1). The position of the
optical object is marked with a cross in all maps and is well
correlated with the position of the radio core. Machalski (1998)
also measured a photometric redshift for 1059+351, which is
z = 0.37 and which differs from that in SDSS/DR5.
1126+293. The VLA 8.4-GHz and MERLIN 5-GHz maps
(Fig. 5) show three radio components, the brighter one proba-
bly being the core that was resolved into a core-jet structure in
M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources 5
1049+384        4994.000 MHz
peak flux density=116.27 mJy/beam, beam size=62 x 38 mas
first contour level=0.40 mJy/beam
RIGHT ASCENSION (J2000)
10 52 11.84 11.83 11.82 11.81 11.80 11.79 11.78 11.77 11.76
38 11 44.6
1049+384        1667.474 MHz
peak flux density=181.64 mJy/beam, beam size=11.6 x 8.2 mas
first contour level=0.09 mJy/beam
RIGHT ASCENSION (J2000)
10 52 11.810 11.805 11.800 11.795 11.790 11.785
38 11 44.14
44.12
44.10
44.08
44.06
44.04
44.02
44.00
43.98
43.96
43.94
1049+384        4987.474 MHz
peak flux density=21.07 mJy/beam, beam size=4.2 x 2.3 mas
first contour level=0.09 mJy/beam
RIGHT ASCENSION (J2000)
10 52 11.805 11.800 11.795 11.790
38 11 44.08
44.07
44.06
44.05
44.04
44.03
44.02
44.01
44.00
43.99
43.98
1049+384        8421.474 MHz
peak flux density=68.39 mJy/beam, beam size=2.6 x 1.2 mas
first contour level=0.15 mJy/beam
RIGHT ASCENSION (J2000)
10 52 11.800 11.798 11.796 11.794 11.792 11.790 11.788 11.786
38 11 44.06
44.05
44.04
44.03
44.02
44.01
44.00
43.99
Fig. 2. The MERLIN 5-GHz (upper left) map and VLBA 1.7, 5, and 8.4-GHz maps of 1049+384. Contours increase by a factor 2,
and the first contour level corresponds to ≈ 3σ. Crosses indicate the position of an optical object found using the SDSS/DR5 .
the 1.7-GHz VLBA image. The source was not detected in the 5
and 8.4-GHz VLBA observations.
1132+374. The 5-GHz MERLIN image shows (Fig. 6) a core-jet
structure that was resolved into a triple CSO object in the 1.7-
GHz VLBA image. The 5 and 8.4-GHz VLBA images show only
two components: a hotspot in the NE lobe and a radio core. This
source is identified with a very high redshift (z = 2.88) galaxy
(Eales & Rawlings, 1996).
1302+356. This source was observed with the VLA at 8.4 GHz
as a part of the JVAS survey (Patnaik et al., 1992). The result-
ing map shows a slightly extended EW object (Fig. 7). The 5-
GHz MERLIN image shows this to be a double source, and the
weak (∼10 mJy) eastern component could be part of a jet. The
bright component was resolved into a diffuse structure in the 1.7-
GHz VLBA image. The 5-GHz VLBA image shows only a sin-
gle component at the position of the maximum emission in the
1.7-GHz VLBA image, which is probably a radio core (Fig. 7).
There is no trace of this source in the 8.4-GHz VLBA image.
1407+369. The 5-GHz MERLIN image shows a core-jet struc-
ture in a NW direction that is resolved into a core and jet in
6 M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources
1056+316        8439.900 MHz
peak flux density=118.41 mJy/beam, beam size=270 x 257 mas
first contour level=0.06 mJy/beam
RIGHT ASCENSION (J2000)
10 59 43.45 43.35 43.25 43.15 43.05
31 24 23
1056+316        4994.000 MHz
peak flux density=80.83 mJy/beam, beam size=60 x 43 mas
first contour level=0.16 mJy/beam
RIGHT ASCENSION (J2000)
10 59 43.28 43.26 43.24 43.22 43.20
31 24 21.2
1056+316        1667.474 MHz
peak flux density=9.10 mJy/beam, beam size=13.9 x 5.5 mas
first contour level=0.30 mJy/beam
RIGHT ASCENSION (J2000)
10 59 43.265 43.255 43.245 43.235 43.225
31 24 20.6
Fig. 3. The VLA 8.4-GHz map, MERLIN 5-GHz map, and VLBA 1.7-GHz map of 1056+316. Contours increase by a factor 2, and
the first contour level corresponds to ≈ 3σ. A cross on the VLA map indicates the position of an optical object found using the
SDSS/DR5.
1059+351        4994.000 MHz
peak flux density=10.03 mJy/beam, beam size=89 x 69 mas
first contour level=0.15 mJy/beam
RIGHT ASCENSION (J2000)
11 02 08.85 08.80 08.75 08.70 08.65 08.60
34 55 10.0
1059+351        1667.474 MHz
peak flux density=8.07 mJy/beam, beam size=10.9 x 7.9 mas
first contour level=0.08 mJy/beam
RIGHT ASCENSION (J2000)
11 02 08.735 08.730 08.725 08.720
34 55 08.80
08.75
08.70
08.65
08.60
Fig. 4. The MERLIN 5-GHz map and VLBA 1.7-GHz map of 1059+351. Contours increase by a factor 2, and the first contour level
corresponds to ≈ 3σ. Crosses indicate the position of an optical object found using the SDSS/DR5.
all the VLBA maps (Fig. 8). The optical object was included
in SDSS/DR5 (RA= 14h09m09.s509, Dec=+36◦42′08.′′15) and is
marked with a cross in all maps. The redshift quoted in Table 1
is photometric.
1425+287. Both the VLA 8.4-GHz and MERLIN 5-GHz images
(Fig. 9) show a double structure for this source. The brighter
component seems to be a radio core, although this cannot be
confirmed because the source was not detected in the VLBA ob-
servations (Fig. 9).
1627+289. Both the VLA 8.4-GHz and MERLIN 5-GHz images
(Fig. 10) show this source to have a core-jet structure. The 1.7-
GHz VLBA image shows only the central extended feature that
was resolved into a core-jet structure in the 5-GHz VLBA image.
The source was not detected in the 8.4-GHz VLBA image.
4. Discussion
4.1. 1045+352 — a BAL quasar
1045+352 is a HiBAL quasar with a very reddened spectrum
showing a C IV broad absorption system (Willott et al., 2002).
Its projected linear size is only 2.1 kpc, which is consistent with
the observation of Becker et al. (2000) that, amongst radio loud
quasars, broad absorption lines are more commonly observed in
the smallest radio sources.
It is a very luminous submillimetre object, which together
with the template dust spectrum adopted by Willott et al. (2002),
indicates this source to be a hyperluminous infrared quasar, with
large amounts of dust in its host galaxy. Although 1045+352
is quite luminous at 151 MHz (2.88 Jy, Waldram et al., 1996),
which suggests the presence of some extended emission and
which, indeed, appears to be present in our MERLIN 5-GHz
M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources 7
1126+293        8439.900 MHz
peak flux density=65.97 mJy/beam, beam size=368 x 310 mas
first contour level=0.08 mJy/beam
RIGHT ASCENSION (J2000)
11 29 23.9 23.8 23.7 23.6 23.5 23.4
29 05 01
04 59
1126+293        4994.000 MHz
peak flux density=60.53 mJy/beam, beam size=62 x43 mas
first contour level=0.14 mJy/beam
RIGHT ASCENSION (J2000)
11 29 21.80 21.75 21.70 21.65
29 05 07.5
1126+293        1667.474 MHz
peak flux density=6.03 mJy/beam, beam size=14.0 x 4.2 mas
first contour level=0.15 mJy/beam
RIGHT ASCENSION (J2000)
11 29 21.762 21.760 21.758 21.756 21.754 21.752 21.750 21.748 21.746
29 05 06.50
06.48
06.46
06.44
06.42
06.40
06.38
06.36
06.34
06.32
06.30
Fig. 5. The VLA 8.4-GHz map, MERLIN 5-GHz map and VLBA 1.7-GHz map of 1126+293. Contours increase by a factor 2, and
the first contour level corresponds to ≈ 3σ.
image, the VLBA maps show the radio structure to be domi-
nated by jets and a core. The 30-GHz flux density of 1045+352
is also high, as would be expected from the VLBA structure.
Consequently, there could be synchrotron contamination of the
submillimetre flux. As shown by Blundell et al. (1999), either
the first-order or second-order polynomials can accurately pre-
dict the shape of the radio spectrum. Both models have been ap-
plied to the radio data of 1045+352 taken from the literature and
from this paper (Fig. 11), and show that a non-thermal compo-
nent could constitute at least ∼40% of the entire 850µm flux (the
parabolic fit). The linear fit agrees with calculations based upon
the 1.25 mm flux measured by Haas et al. (2006), who derived a
value of 94% for the non-thermal component part of the detected
850µm flux. It has to be noted here that the linear fit should be
treated as an upper limit for the synchrotron emission at submil-
limetre wavelengths, since the spectrum may steepen in the inter-
val between 30 GHz and the SCUBA wavebands. However, the
above can indicate values of infrared emission and dust mass of
1045+352 lower than estimated (Willott et al., 2002). This also
appears be consistent with the findings of Willott et al. (2003),
who have shown that there is no difference between the submil-
limetre luminosities of BAL and non-BAL quasars, which sug-
gest that a large dust mass is not required for quasars to show
BALs.
The radio luminosity at 1.4 GHz is high (Table 1), making
this source one of the most radio-luminous BAL quasars, with
a value similar to that of the first known radio-loud BAL QSO
with an FR II structure, FIRST J101614.3+520916 (Gregg et al.,
2000). Following Stocke et al. (1992), a radio-loudness param-
eter, R∗, defined as the K-corrected ratio of the 5-GHz radio
flux to 2500Å optical flux (Table 2) was calculated. For this,
a global radio spectral index, αradio = −0.8 and an optical spec-
tral index, αopt = −1.0, were assumed, and the SDSS g
′ mag-
nitude defined by Fukugita et al. (1996) was converted to the
Johnson-Morgan-Cousins B magnitude using the formula given
by Smith et al. (2002). Corrections were also made for intrin-
8 M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources
1132+374        4994.000 MHz
peak flux density=122.40 mJy/beam, beam size=58 x 44 mas
first contour level=0.18 mJy/beam
RIGHT ASCENSION (J2000)
11 35 05.98 05.96 05.94 05.92 05.90 05.88
37 08 41.6
1132+374        1667.474 MHz
peak flux density=38.64 mJy/beam, beam size=9.5 x 4.0 mas
first contour level=0.40 mJy/beam
RIGHT ASCENSION (J2000)
11 35 05.940 05.938 05.936 05.934 05.932 05.930 05.928 05.926
37 08 40.86
40.84
40.82
40.80
40.78
40.76
40.74
40.72
40.70
40.68
40.66
1132+374         4987.474 MHz
peak flux density=12.57 mJy/beam, beam size=3.1 x 1.2 mas
first contour level=0.14 mJy/beam
RIGHT ASCENSION (J2000)
11 35 05.936 05.934 05.932 05.930 05.928
37 08 40.82
40.80
40.78
40.76
40.74
40.72
40.70
1132+374        8421.474 MHz
peak flux density=8.74 mJy/beam, beam size=2.2 x 1.5 mas
first contour level=0.10 mJy/beam
RIGHT ASCENSION (J2000)
11 35 05.936 05.935 05.934 05.933 05.932 05.931 05.930
37 08 40.83
40.82
40.81
40.80
40.79
40.78
40.77
40.76
40.75
40.74
Fig. 6. The MERLIN 5-GHz (upper left) map and VLBA 1.7, 5, and 8.4-GHz maps of 1132+374. Contours increase by a factor 2,
and the first contour level corresponds to ≈ 3σ.
sic extinction (local to the quasar) calculated by Willott et al.
(2002), who assumed a Milky-Way extinction curve. Even af-
ter correction, log(R∗) > 1, which means that 1045+352 is still
radio-loud object. The angle between the jet axis and the line
of sight can be estimated using the core radio-to-optical lumi-
nosity ratio defined by Wills & Brotherton (1995) as log(RV ) =
log(Lcore) + 0.4MV − 13.69, where Lcore is a radio luminosity of
the core at 5-GHz rest frequency (the core flux density at 5 GHz
were taken from the VLBA image; see also Table 3), and MV
is the K-corrected absolute magnitude calculated using transfor-
mation equation V = g′−0.55(g′−r′)−0.03 (Smith et al., 2002).
From this, a value of ∼3.2 has been obtained for 1045+352, im-
plying an angle in the range θ ∼ 10◦ − 30◦ for the jet in the
observed asymmetric MERLIN 5-GHz radio morphology, and
can explain the high value of the radio-loudness parameter. An
assumption of θ = 20◦ yields the deprojected linear size of the
source of ∼ 6 kpc. As shown by White et al. (2006), BAL QSOs
are systematically brighter than non-BAL objects, which indi-
cates we are looking closer to the jet axis in quasars with BALs.
Based upon the small inclination angles of their BAL quasars,
Zhou et al. (2006) suggest that BAL features can be caused by
polar disk winds. Also, Saikia et al. (2001) and Jeyakumar et al.
(2005) found that the radio properties of CSS sources are con-
sistent with the unified scheme in which the axes of the quasars
are observed close to the line of sight. On the other hand, it
has been shown (Saikia et al., 2001; Jeyakumar et al., 2005) that
many CSS objects interact with an asymmetric medium in the
central regions of their host galaxies, and this can cause the ob-
served asymmetries. It is then likely that, also in the case of the
CSS quasar 1045+352, the environmental asymmetries might
play an important role. The jet power can be estimated from
the relationship between the radio luminosity and the jet power
given by Willott et al. (1999, Eq.(12)). However, because some
of the flux density of the 1045+352 can be beamed, the calcu-
lations have to be treated as an approximation. Assuming the
151-MHz flux density, which accounts for the extended emis-
M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources 9
1302+356        8452.400 MHz
peak flux density=109.96 mJy/beam, beam size=252 x 230 mas
first contour level=0.09 mJy/beam
RIGHT ASCENSION (J2000)
13 04 34.75 34.70 34.65 34.60 34.55 34.50 34.45 34.40 34.35 34.30
35 23 36
1302+356        4994.500 MHz
peak flux density=129.54 mJy/beam, beam size=62 x 39 mas
first contour level=0.18 mJy/beam
RIGHT ASCENSION (B1950)
13 02 13.86 13.84 13.82 13.80 13.78 13.76 13.74 13.72 13.70 13.68
35 39 38.5
1302+356        1667.474 MHz
peak flux density=19.62 mJy/beam, beam size=10.0 x 4.0 mas
first contour level=0.14 mJy/beam
RIGHT ASCENSION (J2000)
13 04 34.502 34.500 34.498 34.496 34.494 34.492 34.490 34.488 34.486
35 23 33.64
33.62
33.60
33.58
33.56
33.54
33.52
33.50
33.48
33.46
33.44
1302+356        4987.474 MHz
peak flux density=4.23 mJy/beam, beam size=3.8 x 1.5 mas
first contour level=0.07 mJy/beam
RIGHT ASCENSION (J2000)
13 04 34.498 34.497 34.496 34.495 34.494 34.493 34.492
35 23 33.57
33.56
33.55
33.54
33.53
33.52
33.51
33.50
33.49
Fig. 7. The VLA 8.4-GHz map (upper left), MERLIN 5-GHz map (upper right) and VLBA 1.7 and 5-GHz maps of 1302+356.
Contours increase by a factor 2, and the first contour level corresponds to ≈ 3σ.
sion and the radio emission from the jets, the jet kinetic power is
Q jet ∼ 10
44erg sec−1.
The projected linear size D of a radio quasar or radio
galaxy can be approximately related to the time, from the trig-
gering of activity, as the relationship between these variables
is only weakly dependent upon the radio luminosity. Using
the model of radio source evolution from Willott et al. (1999),
the age of 1045+352 was estimated to be ∼ 105 years (see
also Willott et al., 2002; Rawlings et al., 2004). For the calcu-
lations we assumed: θ = 20◦, β = 1.5, c1 = 2.3, n100 =
3000 e− m−3, a0 = 100 kpc (see Willott et al., 1999, for defini-
tions). Both the MERLIN and VLBA high frequency images
have revealed that two cycles of activity may have occurred dur-
ing these ∼ 105 years. The extended NE/SW emission is prob-
ably the remnant of the first phase of activity, which has been
very recently replaced by a new phase of activity pointing in a
NW/SE direction. It has been shown by Stanghellini et al. (2005)
that the extended emission observed for small-scale objects can
be the remnants of an earlier period of activity in these sources.
In the case of 1045+352, renewal of activity has been accompa-
nied by a reorientation of the jet axis.
Several processes can be used to explain a jet reorientation
in AGNs. There are strong observational and theoretical grounds
for believing that accretion disks around black holes may be
twisted or warped, and this can be caused by a number of pos-
sible physical processes. In particular, if there is a misalignment
between the axis of rotating black hole and the axis of its rotating
accretion disk, then the Lense-Thirring precession produces a
warp in the disk. This process is called the Bardeen-Peterson ef-
fect (Bardeen & Petterson, 1975). According to Pringle (1997),
disk warping can also be induced by internal instabilities in
the accretion disk caused by radiation pressure from the central
source.
A reorientation of the jet axis may also result from a merger
with another black hole. Merritt & Ekers (2002) have shown that
a rapid change in jet orientation can be caused by even a mi-
10 M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources
1407+369        4994.500 MHz
peak flux density=109.87 mJy/beam, beam size=52 x 46 mas
first contour level=0.12 mJy/beam
RIGHT ASCENSION (J2000)
14 09 09.56 09.54 09.52 09.50 09.48 09.46
36 42 08.8
1407+369        1667.474 MHz
peak flux density=147.37 mJy/beam, beam size=10.2 x 5.1 mas
first contour level=0.18 mJy/beam
RIGHT ASCENSION (J2000)
14 09 09.516 09.512 09.508 09.504 09.500
36 42 08.30
08.25
08.20
08.15
08.10
08.05
1407+369        4987.474 MHz
peak flux density=60.90 mJy/beam, beam size=3.6 x 2.0 mas
first contour level=0.16 mJy/beam
RIGHT ASCENSION (J2000)
14 09 09.512 09.510 09.508 09.506 09.504
36 42 08.22
08.20
08.18
08.16
08.14
08.12
08.10
1407+369        8421.474 MHz
peak flux density=24.34 mJy/beam, beam size=2.1 x 1.0 mas
first contour level=0.15 mJy/beam
RIGHT ASCENSION (J2000)
14 09 09.511 09.510 09.509 09.508 09.507 09.506
36 42 08.18
08.17
08.16
08.15
08.14
08.13
08.12
Fig. 8. The MERLIN 5-GHz map (upper left) and VLBA 1.7, 5, and 8.4-GHz maps of 1407+369. Contours increase by a factor 2,
and the first contour level corresponds to ≈ 3σ. Crosses indicate the position of an optical object found using the SDSS/DR5.
nor merger because of a spin-flip of the central active black
hole arising from the coalescence of inclined binary black holes.
According to Liu (2004), the Bardeen-Peterson effect can also
cause a realignment of a rotating SMBH and a misaligned ac-
cretion disk, where the timescale of such a realignment t < 105
years. If it is assumed that the typical speed of advance of ra-
dio lobes of young AGNs is υ ∼0.3c (Owsianik et al., 1998;
Giroletti et al., 2003; Polatidis & Conway, 2003), then distorted
jets of length, tυ <10 kpc for some CSS and GPS sources should
be observed, although the character of these disturbances is not
known. Liu (2004) shows that the interaction/realignment of
a binary and its accretion disk leads to the development of X-
shaped sources. 1045+352 is not a typical X-shaped source like
3C 223.1 or 3C 403 (Dennett-Thorpe et al., 2002; Capetti et al.,
2002). However, according to Cohen et al. (2005) the realign-
ment of a rotating SMBH followed by a repositioning of the ac-
cretion disk and jets is a plausible interpretation for misaligned
radio structures, even if they are not conspicuously X-shaped.
It is likely that in young sources such as 1045+352, the
gas has not yet settled into a regular disk following a merger
event and that separate clouds of gas and dust reaching the very
central regions of the source at different times disturb the sta-
bility of the accretion disk and affect the jet formation. Later,
these clouds could cause a renewal of activity. Numerical simu-
lations of colliding galaxies show that these usually merge com-
pletely after a few encounters in timescales up to ∼ 108 years
(Barnes & Hernquist, 1996). According to Schoenmakers et al.
(2000), multiple encounters between interacting galaxies can
cause interruptions of activity and lead to the many types of
sources that are observed in a restarted phase, such as double-
double radio galaxies. Nevertheless, it is unclear whether such
encounters can cause jet reorientation. On the other hand, the
dense medium of a host galaxy can frustrate the jets, and their
collisions with the dense surrounding medium can cause rapid
bends through large angles. In the case of 1045+352, the VLBA
images at the higher frequencies seem to show a jet emerging in
M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources 11
1425+287       8439.900 MHz
peak flux density=64.89 mJy/beam, beam size=305 x 267 mas
first contour level=0.08 mJy/beam
RIGHT ASCENSION (J2000)
14 27 38.7 38.6 38.5 38.4 38.3 38.2
28 33 17
1425+287        4994.500 MHz
peak flux density=62.37 mJy/beam, beam size=74 x 40 mas
first contour level=0.80 mJy/beam
RIGHT ASCENSION (J2000)
14 27 40.40 40.35 40.30 40.25 40.20
28 33 27.5
Fig. 9. The VLA 8.4-GHz map and MERLIN 5-GHz map of 1425+287. Contours increase by a factor 2, and the first contour level
corresponds to ≈ 3σ.
Frequency (Hz)
1045+352
Fig. 11. Spectral Energy Distribution (SED) of 1045+352 from
radio to submillimetre wavelengths. The errors are smaller than
the size of the symbols; 1.25 mm point (Haas et al., 2006) is
shown as a triangle, 850µm and 450 µm points (Willott et al.,
2002) are shown as filled circles, radio observations are shown
as asterisks. The solid curve is the parabolic fit f (x) = ax2+bx+c
to all radio data (yi), with a = −0.14, b = 1.91, c = −5.68, and
reduced χ2 = 12. The dashed curve is the linear fit f (x) = ax+ b
to radio data with ν > 1GHz, with a = −0.86, b = 7.91, and
reduced χ2 = 0.5.
a S/SE direction, but being bent through ∼ 60◦ to a NE direction
in the lower resolution 1.7-GHz image. The MERLIN lower res-
olution 5-GHz image might indicate that the jet has been bent
again and now emerges from the core in a NW direction.
It is difficult to find a convincing argument in favour of one
of the above-mentioned alternatives or to rule any of them out
based upon the extensive multifrequency data on 1045+352 pre-
sented here. However, if it is assumed that a merger is the most
probable cause of the ignition and restart of activity in radio
galaxies, this could mean that 1045+352 has undergone two
merger events in a very short period of time (∼ 105), which is un-
Table 2. 1045+352 properties
Parameter Value
u′ 22.12
g′ 21.38
r′ 20.81
i′ 20.14
z′ 20.08
AB 2.0
MB -22.05 (-24.05)
AV 1.5
MV -22.83 (-24.33)
log(R∗)(total) 4.9 (4.1)
log(R∗)(core) 3.8 (3.0)
Notes: Optical photometry from SDSS, corrected for Galactic extinc-
tion. AV taken from Willott et al. (2002). Quantities in parentheses are
corrected for intrinsic extinction.
likely. More probable is that the ignition of activity in 1045+352
has occurred during a merger event that is, as yet, incomplete and
that disturbed, misaligned radio jets result from the realignment
of a rotating SMBH or intermittent gas injection that interrupts
jet formation.
4.2. Other nine sources
Three sources from our sample (1126+293, 1407+369,
1627+289) show one- or two-sided core-jet structures, indicat-
ing that they are in an active phase of their evolution, although
the core-jet structure of 1126+293 is controversial. Our images
indicate that the western components are parts of the jet, which is
possibly precessing or being bent by interactions with the inter-
stellar medium. They could, however, also be hotspots of a radio
lobe. Unfortunately, our high frequency VLBA observations are
not sensitive enough to settle this problem. Three other sources
(1056+316, 1132+374, 1425+287) have visible radio cores and
parts of lobes or hotspots, indicating activity. 1132+374 is a CSO
object. In the case of one source, 1059+351, the VLBA obser-
12 M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources
1627+289        8439.900 MHz
peak flux density=75.42 mJy/beam, beam size=271 x 263 mas
first contour level=0.07 mJy/beam
RIGHT ASCENSION (J2000)
16 29 12.50 12.45 12.40 12.35 12.30 12.25 12.20 12.15 12.10 12.05
28 51 37
1627+289        4994.500 MHz
peak flux density=77.77 mJy/beam, beam size=70 x 39 mas
first contour level=0.15 mJy/beam
RIGHT ASCENSION (J2000)
16 29 12.36 12.34 12.32 12.30 12.28 12.26 12.24 12.22 12.20
28 51 35.5
1627+289        1667.474 MHz
peak flux density=40.35 mJy/beam, beam size=10.6 x 5.1 mas
first contour level=0.30 mJy/beam
RIGHT ASCENSION (J2000)
16 29 12.270 12.268 12.266 12.264 12.262 12.260 12.258
28 51 34.16
34.14
34.12
34.10
34.08
34.06
34.04
34.02
34.00
33.98
33.96
1627+289        4987.474 MHz
peak flux density=5.57 mJy/beam, beam size=4.2 x 1.9 mas
first contour level=0.15 mJy/beam
RIGHT ASCENSION (J2000)
16 29 12.267 12.266 12.265 12.264 12.263 12.262 12.261 12.260
28 51 34.11
34.10
34.09
34.08
34.07
34.06
34.05
34.04
34.03
34.02
Fig. 10. The VLA 8.4-GHz map (upper left), MERLIN 5-GHz map (upper right), and VLBA 1.7 and 5-GHz maps of 1627+289.
Contours increase by a factor 2, and the first contour level corresponds to ≈ 3σ.
vations show only a radio core, although the 5-GHz MERLIN
image of 1059+351 also shows remnants of the two radio
lobes of its “S” shaped structure visible at the VLA resolutions
(Machalski & Condon, 1983; Machalski, 1998). According to
Taylor et al. (1996) and Readhead et al. (1996), “S” symmetry
is observed in many compact sources and can be explained
by precession of the central engine. 1059+351 is the largest
source in our sample with a linear size of 45 kpc based upon
its largest angular size measured from 1.46-GHz VLA image
(Machalski & Condon, 1983).
The compact 1049+384 and 1302+356 steep spectrum
sources appeared to be low-frequency variables (LFV) at
151 MHz with very high (≥0.99) probabilities that their variabil-
ity is real (Minns & Riley, 2000). According to them, LFV ob-
jects are generally more compact than other CSS sources and
tend to exhibit steeper spectra than typical CSS sources. This
may be because of rapid spectral ageing, which might be ex-
pected for frustrated sources, or it might simply be because the
sources are at very high redshifts.
5. Conclusions
VLBA, VLA, and MERLIN images of ten compact steep
spectrum sources have been presented. One of these sources,
1045+352, is a very radio-luminous BAL quasar, whose com-
plex structure suggests restarted activity. This may have resulted
either from a merger event or from the infall of a cloud of gas,
that had cooled in the halo of the galaxy into the core region of
the source. The asymmetric radio jets of 1045+352 and the es-
timated angle suggest that some of the emission can be boosted,
although the intrinsic asymmetries cannot be ruled out. It has
also been confirmed that the 850µm flux of 1045+352 can be
severely contaminated by synchrotron emission, which may sug-
gest less than previously estimated values of infrared emission
and dust mass. Most of the radio-loud BAL quasars detected to
M. Kunert-Bajraszewska and A. Marecki: FIRST-based survey of compact steep spectrum sources 13
Table 3. Flux densities of sources principal components from the VLBA observations
Source RA DEC S1.7 GHz S5 GHz S8.4GHz θ1 θ2 PA
Name h m s ◦ ′ ′′ mJy mJy mJy mas mas ◦
(1) (2) (3) (4) (5) (6) (7) (8) (9)
1045+352 10 48 34.248 34 57 25.044 303.2 − − 15.0 11.0 60
10 48 34.249 34 57 25.061 − 3.5 − 2.0 1.0 76
10 48 34.248 34 57 25.041 − 21.8 7.1 7.0 1.0 101
10 48 34.248 34 57 25.043 − 32.7 12.3 4.0 3.0 95
1049+384 10 52 11.803 38 11 44.018 13.6 − − 3.0 1.0 14
10 52 11.797 38 11 44.027 11.4 3.9 6.9 2.0 2.0 121
10 52 11.789 38 11 44.031 182.1 33.6 12.9 8.0 1.0 119
10 52 11.787 38 11 44.048 218.5 23.9 2.3 5.0 3.0 177
1056+316 10 59 43.254 31 24 20.106 8.8 − − 0.9 0.1 7
10 59 43.235 31 24 20.538 43.6 − − 33.0 8.0 6
1059+351 11 02 08.726 34 55 08.709 8.1 − − 0.7 0.3 124
1126+293 11 29 21.755 29 05 06.402 7.3 − − 3.0 1.0 84
11 29 21.753 29 05 06.401 10.4 − − 13.0 4.0 53
1132+374 11 35 05.934 37 08 40.810 124.1 6.6 1.6 18.0 2.0 57
11 35 05.932 37 08 40.775 36.3 13.8 9.4 2.0 0.4 8
11 35 05.931 37 08 40.715 14.5 − − 5.0 0.8 105
1302+356 13 04 34.495 35 23 33.534 46.8 5.9 − 11.0 6.0 97
13 04 34.494 35 23 33.538 60.5 − − 15.0 7.0 147
1407+369 14 09 09.504 36 42 08.195 81.0 1.9 − 17.0 3.0 138
14 09 09.508 36 42 08.164 192.8 76.7 42.0 8.0 1.5 141
14 09 09.508 36 42 08.152 − 9.5 4.8 0.7 0.2 140
1627+289 16 29 12.264 28 51 34.062 111.5 8.1 − 10.0 6.0 58
Description of the columns: (1) source name in the IAU format; (2) component right ascension (J2000) as measured at 1.7 GHz; (3) component
declination (J2000) as measured at 1.7 GHz; (4) VLBA flux density in mJy at 1.7 GHz from the present paper; (5) VLBA flux density in mJy at
5 GHz from the present paper; (6) VLBA flux density in mJy at 8.4 GHz from the present paper; (7) deconvolved component major axis angular
size at 1.7 GHz obtained using JMFIT; (8) deconvolved component minor axis angular size at 1.7 GHz obtained using JMFIT; (9) deconvolved
major axis position angle at 1.7 GHz obtained using JMFIT. In the case the component is not visible in 1.7 GHz map the values for the last three
columns are taken from the 5-GHz image.
date have very compact radio structures similar to GPS and CSS
sources which are thought to be young. Therefore, the compact
structure and young age of 1045+352 fit well to the evolutionary
interpretation of radio-loud BAL QSOs.
According to the evolutionary model recently proposed by
Lipari & Terlevich (2006), BAL quasars are young systems with
composite outflows, and they are accompanied by absorption
clouds. The radio-loud systems may be associated with the later
stages of evolution, when jets have removed the clouds respon-
sible for the generation of BALs. The effect of orientation could
play a secondary role here. The above could explain the rarity of
extended radio structures showing BAL features (Gregg et al.,
2006).
Acknowledgements.
The VLBA is operated by the National Radio Astronomy Observatory (NRAO),
a facility of the National Science Foundation (NSF) operated under cooperative
agreement by Associated Universities, Inc. (AUI).
This research has made use of the NASA/IPAC Extragalactic Database (NED),
which is operated by the Jet Propulsion Laboratory, California Institute
of Technology, under contract with the National Aeronautics and Space
Administration.
Use has been made of the Sloan Digital Sky Survey (SDSS) Archive. The
SDSS is managed by the Astrophysical Research Consortium (ARC) for the
Participating Institutions: The University of Chicago, Fermilab, the Institute for
Advanced Study, the Japan Participation Group, The Johns Hopkins University,
Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy
(MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State
University, University of Pittsburgh, Princeton University, the United States
Naval Observatory, and the University of Washington.
We thank M. Gawroński for his help with the OCRA-p observations. The OCRA
project was supported by the Polish Ministry of Science and Higher Education
under grant 5 P03D 024 21 and the Royal Society Paul Instrument Fund.
We thank P.J. Wiita for a discussion and P. Thomasson for reading of the paper
and a number of suggestions.
This work was supported by the Polish Ministry of Science and Higher
Education under grant 1 P03D 008 30.
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List of Objects
‘1045+352’ on page 3
‘1049+384’ on page 3
‘1056+316’ on page 3
‘1059+351’ on page 3
‘1126+293’ on page 4
‘1132+374’ on page 4
‘1302+356’ on page 4
‘1407+369’ on page 5
‘1425+287’ on page 5
‘1627+289’ on page 5
	Introduction
	The observations and data reduction
	Comments on individual sources
	Discussion
	1045+352 — a BAL quasar
	Other nine sources
	Conclusions
