Optical and radio properties of extragalactic radio sources with recurrent jet activity

We present a sample of 74 radio sources with recurrent jet activity. The sample consists of 67 galaxies, 2 quasars and 5 unidentified sources, selected from the published data or are newly recognized. The sample's redshift range is 0.002 < z < 0.7 and the size of inner and outer structures varies from 0.02 to 4248 kpc. We analyse the optical and radio properties of the sample and compare them with the characteristics of ordinary one-off FRII radio sources. With the help of stellar population modelling, we derive black hole masses and stellar masses of host galaxies of 35 restarting radio sources, finding that the black hole masses in restarting radio sources are comparable to those of typical single-cycle FRII radio sources. The obtained median values of log M$_{BH}$ are 8.58 and 8.62 M$_{\odot}$ Unlike the black hole masses, the stellar masses in restarting radio sources tend to be smaller than in the FRII sources. Although the stellar populations of the hosts of recurrent activity sources are dominated by old stars, a significant fraction of young stars can be observed as well. Based on the Sloan Digital Sky Survey photometric observations, we also analyse the morphology of the host galaxies and obtained significantly smaller concentration indices for the restarting radio sources when compared to the classical FRII hosts. This effect can be interpreted as a result of frequent merger events in the history of host galaxies of restarting radio sources.Comment: 21 pages, 17 figure

J1420--0545: The radio galaxy larger than 3C236

We report the discovery of the largest giant radio galaxy, J1420-0545: a FR type II radio source with an angular size of 17.4' identified with an optical galaxy at z=0.3067. Thus, the projected linear size of the radio structure is 4.69 Mpc (if we assume that H_{0}=71 km\s\Mpc, Omega_{m}=0.27, and Omega_{\Lambda}=0.73). This makes it larger than 3C236, which is the largest double radio source known to date. New radio observations with the 100 m Effelsberg telescope and the Giant Metrewave Radio Telescope, as well as optical identification with a host galaxy and its optical spectroscopy with the William Herschel Telescope are reported. The spectrum of J1420-0545 is typical of elliptical galaxies in which continuum emission with the characteristic 4000A discontinuity and the H and K absorption lines are dominated by evolved stars. The dynamical age of the source, its jets' power, the energy density, and the equipartition magnetic field are calculated and compared with the corresponding parameters of other giant and normal-sized radio galaxies from a comparison sample. The source is characterized by the exceptionally low density of the surrounding IGM and an unexpectedly high expansion speed of the source along the jet axis. All of these may suggest a large inhomogeneity of the IGM.Comment: 20 pages, 5 figures, 3 table

CGCG 292-057 - a radio galaxy with merger-modulated radio activity

We announce the discovery of a unique combination of features in a radio source identified with the merger galaxy CGCG 292-057. The radio galaxy both exhibits a highly complex, X-like structure and shows signs of recurrent activity in the form of double-double morphology. The outer lobes of CGCG 292-057 are characterized by low radio power, P_{1400MHz} \simeq 2 * 10^{24} W\Hz^{-1}, placing this source below the FRII/FRI luminosity threshold, and are highly polarized (almost 20 per cent at 1400 MHz) as is typical of X-shaped radio sources. The host is a LINER-type galaxy with a relatively low black hole mass and double-peaked narrow emission lines. These features make this galaxy a primary target for studies of merger-triggered radio activity.Comment: 7 pages, 5 figures, submitted to MNRA

FRII radio galaxies in the SDSS: Observational facts

Starting from the Cambridge Catalogues of radio sources, we have created a sample of 401 FRII radio sources that have counterparts in the main galaxy sample of the 7th Data release of the SDSS and analyse their radio and optical properties. We find that the luminosity in the Halpha line - which we argue gives a better measure of the total emission-line flux than the widely used O[III] luminosity - is strongly correlated with the radio luminosity P1.4GHz. We show that the absence of emission lines in about one third of our sample is likely due to a detection threshold and not to a lack of optical activity. We find that the properties of FRII galaxies are mainly driven by the Eddington parameter LHa/"MBH" or, equivalently, P1.4GHz/"MBH". Radio galaxies with hot spots are found among the ones with the highest values of P1.4GHz/"MBH". Compared to classical AGN hosts in the main galaxy sample of the SDSS, our FRII galaxies show a larger proportion of objects with very hard ionizing radiation field and large ionization parameter. A few objects are, on the contrary, ionized by a softer radiation field. We find that the black hole masses and stellar masses in FRII galaxies are very closely related. A comparison sample of line-less galaxies in the SDSS follows the same relation, although on average the masses are smaller. This suggests that the FRII radio phenomenon occurs in normal elliptical galaxies, preferentially in the most massive ones. Although most FRII galaxies are old, some contain traces of young stellar populations. Such young populations are not seen in normal line-less galaxies, suggesting that the activity in some FRII galaxies may be triggered by recent star formation. The "MBH"-Mgal relation in a comparison sample of radio-quiet AGNs from the SDSS is very different, suggesting that galaxies which are still forming stars are also still building their central black holes.Comment: Accepted for publication in MNRAS: 26 pages, 29 figures, 1 tabl

What Distinguishes the Host Galaxies of Radio-loud and Radio-quiet AGNs?

International audienc

Identifying Radio-active Galactic Nuclei among Radio-emitting Galaxies

International audienceBasing our analysis on ROGUE I, a catalog of over 32,000 radio sources associated with optical galaxies, we provide two diagnostics to select the galaxies where the radio emission is dominated by an active galactic nucleus (AGN), referred to in the paper as radio-AGNs. Each of these diagnostics can be applied independently. The first one, dubbed MIRAD, compares the flux FW3 in the W3 mid-infrared band of the Wide-field Infrared Survey Explorer telescope, with the radio flux at 1.4 GHz, F1.4. MIRAD requires no optical spectra. The second diagnostic, dubbed DLM, compares the 4000 Å break strength, Dn(4000), with the radio luminosity per unit stellar mass. The DLM diagram has already been used in the past, but not as stand-alone. For these two diagrams, we propose simple, empirical dividing lines that result in the same classification for the objects in common. These lines correctly classify as radio-AGN 99.5% of the extended radio sources in the ROGUE I catalog, and as star-forming galaxies 98%-99% of the galaxies identified as such by their emission-line ratios. Both diagrams clearly show that radio-AGNs are preferentially found among elliptical galaxies and among galaxies hosting the most massive black holes. Most of the radio sources classified as radio-AGNs in the MIRAD or DLM diagrams are either optically weak AGNs or retired galaxies

Physical parameters of components in close binary systems. V

The paper presents combined spectroscopic and photometric orbital solutions for ten close binary systems: CN And, V776 Cas, FU Dra, UV Lyn, BB Peg, V592 Per, OU Ser, EQ Tau, HN UMa and HT Vir. The photometric data consist of new multicolor light curves, while the spectroscopy has been recently obtained within the radial velocity program at the David Dunlap Observatory (DDO). Absolute parameters of the components for these binary systems are derived. Our results confirm that CN And is not a contact system. Its configuration is semi-detached with the secondary component filling its Roche lobe. The configuration of nine other systems is contact. Three systems (V776 Cas, V592 Per and OU Ser) have high (44-77%) and six (FU Dra, UV Lyn, BB Peg, EQ Tau, HN UMa and HT Vir) low or intermediate (8-32%) fill-out factors. The absolute physical parameters are derived

Physical parameters of components in close binary systems : IV

The paper presents new geometric, photometric and absolute parameters, derived from combined spectroscopic and photometric solutions, for ten contact binary systems. The analysis shows that three systems (EF Boo, GM Dra and SW Lac) are of W-type with shallow to moderate contact. Seven systems (V417 Aql, AH Aur, YY CrB, UX Eri, DZ Psc, GR Vir and NN Vir) are of A-type in a deep contact configuration. For six systems (V417 Aql, YY CrB, GM Dra, UX Eri, SW Lac and GR Vir) a spot model is introduced to explain the O'Connell effect in their light curves. The photometric and geometric elements of the systems are combined with the spectroscopic data taken at David Dunlap Observatory to yield the absolute parameters of the components

The W UMa-type Stars Program : first results, current status and perspectives

We present the results of a statistical investigation of the period-color and period-bolometric magnitude relations using a carefully selected sample of 120 contact systems with known physical parameters