2001A&A...366....7V


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.22CEST12:08:34

2001A&A...366....7V - Astronomy and Astrophysics, volume 366, 7-25 (2001/1-4)

Radio galaxies at z∼ 2.5: results from Keck spectropolarimetry.

VERNET J., FOSBURY R.A.E., VILLAR-MARTIN M., COHEN M.H., CIMATTI A., DI SEREGO ALIGHIERI S. and GOODRICH R.W.

Abstract (from CDS):

In classifying the ensemble of powerful extragalactic radio sources, considerable evidence has accumulated that radio galaxies and quasars are orientation-dependent manifestations of the same parent population: massive spheroidal galaxies containing correspondingly massive black holes. One of the key factors in establishing this unification has been the signature of a hidden quasar detected in some radio galaxies in polarized light. The obscuration of our direct view of the active nucleus usually, but not necessarily exclusively, by a thick nuclear disk or torus can act conveniently as a ``natural coronograph" that allows a much clearer view of the host of a radio galaxy than of a quasar. In this study, we exploit the opportunity to eliminate the quasar glare by performing sensitive spectropolarimetry with the Keck II telescope of a sample of radio galaxies with redshifts around 2.5. This represents the epoch when quasars were many times more common that they are now and is likely to be the period during which their host galaxies were being assembled into what become the most massive galaxies in the Universe today. We show that dust-reflected quasar light generally dominates the restframe ultraviolet continuum of these sources and that a highly clumped scattering medium results in almost grey scattering of the active galactic nucleus photons. The observations, however, do not exclude a substantial star formation rate averaged over a Gyr of evolution. The sub-mm reradiation from the scattering dust is likely to represent only a small fraction (∼10%) of the total far infrared luminosity. An analysis of the emission lines excited in the interstellar medium of the host galaxy by the hard quasar radiation field reveals evidence of a dramatic chemical evolution within the spheroid during this epoch. Secondary nitrogen production in intermediate mass stars produces a characteristic signature in the NV/CIV and NV/HeII line ratios which has been seen previously in the broad line region of quasars at similar redshifts. We find intriguing correlations between the strengths of the Lyα and N v emission lines and the degree of ultraviolet continuum polarization which may represent the dispersal of dust associated with the chemical enrichment of the spheroid.

Abstract Copyright:

Journal keyword(s): techniques: polarimetric - galaxies: active - galaxies: evolution - galaxies: abundances - galaxies: starburst - scattering

Errata: Erratum vol. 370, p. 407 (2001)

Simbad objects: 27

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Number of rows : 27

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 PMN J0214-1158 rG 02 14 17.4 -11 58 47           ~ 56 1
2 Feige 22 WD* 02 30 16.6276774109 +05 15 50.698326875 11.939 12.746 12.798 12.901 13.004 DA2.5 114 0
3 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 3984 2
4 BD+52 913 WD* 05 05 30.6182785658 +52 49 51.920797126 10.25 11.44 11.69 11.93 12.108 DA.8 959 0
5 4C 41.17 rG 06 50 52.098 +41 30 30.53           ~ 315 1
6 3C 183 rG 07 35 22.4534192750 +43 44 25.039803733           ~ 47 1
7 NVSS J083053+191314 rG 08 30 53.44 +19 13 15.7           ~ 65 1
8 PMN J0945-2429 rG 09 45 32.7 -24 28 49           ~ 89 1
9 [VV96] J102434.5+470911 Sy1 10 24 34.5 +47 09 11     20.5     ~ 473 0
10 3C 256 rG 11 20 43.022 +23 27 55.21   21.5       ~ 118 0
11 BD+25 2534 HS* 12 37 23.5157891619 +25 03 59.871049394 9.117 10.26 10.59 10.642 10.809 sdB1(k) 202 0
12 BD+18 2647 HS* 12 41 51.7901702595 +17 31 19.750592670 10.261 11.70 11.63 11.969 12.159 sdOpec 160 1
13 4C 03.24 rG 12 45 38.4 +03 23 18           ~ 66 1
14 HZ 44 HS* 13 23 35.2632775627 +36 07 59.545982652 10.186 11.42 11.65 12.00 11.995 sdBN0VIIHe28 362 0
15 4C -00.54 rG 14 13 15.2 -00 23 01           ~ 44 0
16 NAME MS 1512-cB58 AGN 15 14 22.2751 +36 36 25.674     20.64   20.35 ~ 315 0
17 CNOC MS 1512 101094 G 15 14 22.482 +36 36 21.08           ~ 146 1
18 BD+33 2642 pA* 15 51 59.8857490337 +32 56 54.327647794 9.806 10.61 10.73 10.884 10.961 O7p 367 0
19 NGC 6052 IG 16 05 12.8707837896 +20 32 32.613940524 13.01 13.44 13.00     ~ 329 2
20 3C 372 rG 18 10 55.70 +40 45 23.6   22.1       ~ 64 1
21 NGC 6764 LIN 19 08 16.348 +50 55 59.14   15.00 14.32     ~ 268 1
22 4C 48.48 rG 19 33 05.27 +48 11 41.8           ~ 37 1
23 Schulte 12 s*b 20 32 40.9574572449 +41 14 29.276333992 16.1 14.45 11.702     B3-4Ia+ 352 0
24 4C 23.56 EmG 21 07 14.82 +23 31 45.0           ~ 93 0
25 BD+28 4211 HS* 21 51 11.0220905905 +28 51 50.366090892 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 721 0
26 QSO B2226-3905 QSO 22 29 51.3836374835 -38 50 03.442904142   18.6       ~ 17 1
27 GD 248 WD* 23 26 06.5870632822 +16 00 19.282796891 14.431 15.206 15.112 15.034 14.977 DA5 74 0

    Equat.    Gal    SGal    Ecl

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2019.10.22-12:08:34

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