An unbiased sample of bright southern compact steep spectrum and gigahertz peaked spectrum sources

Randall, Kate; Hopkins, A. M.; Norris, R. P.; Edwards, Philip

doi:10.1111/j.1365-2966.2011.19116.x

Cited by 43 publications

(46 citation statements)

References 71 publications

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“…It is an archetypal GPS radio source (Randall et al 2011), peaking at an observed frequency of 1 GHz, with optically thick and thin spectral indices 4 of α = 0.83 and −0.74, respectively (see Fig. 1).…”

Section: Pks B1740−517mentioning

confidence: 99%

Discovery of H i gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder

Allison¹,

Sadler²,

Moss³

et al. 2015

Mon. Not. R. Astron. Soc.

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We report the discovery of a new 21-cm H I absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5 -1015.5 MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between z = 0.4 and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at z = 0.44 towards the GHz-peaked spectrum radio source PKS B1740−517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for H I absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the H I gas is intrinsic to the host galaxy of the radio source. The narrow [O III] emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the XMM-Newton satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The H I absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s −1 and fractional depths from 0.2 to 20 per cent. In addition to systemic H I gas, in a circumnuclear disc or ring structure aligned with the radio jet, we find evidence for a possible broad outflow of neutral gas moving at a radial velocity of v ∼ 300 km s −1 . We infer that the expanding young radio source (t age ≈ 2500 yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of ∼ 1 M yr −1 .

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Section: Pks B1740−517mentioning

confidence: 99%

Discovery of H i gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder

Allison¹,

Sadler²,

Moss³

et al. 2015

Mon. Not. R. Astron. Soc.

Self Cite

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“…The compact inverted-spectrum AGN core is similar to gigahertz-peaked spectrum sources (GPSs) that exhibit a peak in their radio spectra between 1 and 5 GHz and an inverted-shape spectrum at lower frequencies (Fanti 2009). GPSs are interpreted as radio AGNs in early phases of their evolution; therefore, compact inverted-spectrum radio cores of TDRGs may be considered as an indication of recent AGN activity (Randall et al 2011;Orienti 2016). Indeed, some DDRGs are known to show a mildly inverted spectrum of the core (Machalski et al 2010).…”

Section: Radio Morphologymentioning

confidence: 99%

J1216+0709: A Radio Galaxy With Three Episodes of Agn Jet Activity

Singh

Ishwara‐Chandra

Kharb

et al. 2016

ApJ

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We report the discovery of a "triple-double radio galaxy," J1216+0709, detected in deep low-frequency Giant Metrewave Radio Telescope (GMRT) observations. J1216+0709 is only the third radio galaxy, after B0925+420 and Speca, with three pairs of lobes resulting from three different episodes of active galactic nucleus (AGN) jet activity. The 610 MHz GMRT image clearly displays an inner pair of lobes, a nearly coaxial middle pair of lobes, and a pair of outer lobes that is bent with respect to the axis of the inner pair of lobes. The total end-to-end projected sizes of the inner, middle, and outer lobes are 40″ (∼95 kpc), 1 65 (∼235 kpc), and 5 7 (∼814 kpc), respectively. Unlike the outer pair of lobes, both the inner and middle pairs of lobes exhibit asymmetries in arm lengths and flux densities, but in the opposite sense, i.e., the eastern sides are farther and also brighter than the western sides, thus, suggesting the possibility of the jet being intrinsically asymmetric rather than due to a relativistic beaming effect. The host galaxy is a bright elliptical (m r ∼ 16.56) with M SMBH ∼ 3.9 × 10 9 M e and a star formation rate of ∼ -+ 4.66 1.61 4.65 M e yr −1 . The host galaxy resides in a small group of three galaxies (m r 17.77) and is possibly going through an interaction with faint dwarf galaxies in the neighborhood, which may have triggered the recent episodes of AGN activity.

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“…CSS and gigahertz-peaked spectrum (GPS) galaxies are bright radio sources, which are considered to be young radio galaxies based on their peaked radio spectra and compact jet structure (e.g., O'Dea 1998;Stanghellini 2003;Fanti et al 2011;Randall et al 2011, and references therein). The same scenario has been discussed for γ-NLS1 due to their low black hole masses and high accretion rates (e.g., Foschini et al 2015).…”

Section: Comparison With Compact Steep-spectrum Sourcesmentioning

confidence: 99%

The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004−447

Kreikenbohm

Schulz

Kadler

et al. 2015

A&A

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As part of the TANAMI multiwavelength progam, we discuss new X-ray observations of the γ-ray and radio-loud narrow line Seyfert 1 galaxy (γ-NLS1) PKS 2004−447. The active galaxy is a member of a small sample of radio-loud NLS1s detected in γ-rays by the Fermi Large Area Telescope. It stands out for being the radio-loudest and the only southern-hemisphere source in this sample. We present results from our X-ray monitoring program comprised of Swift snapshot observations from 2012 through 2014 and two new X-ray observations with XMM-Newton in 2012. Supplemented by archival data from 2004 and 2011, our data set allows for a careful analysis of the X-ray spectrum and variability of this peculiar source. The (0.5-10) keV spectrum is described well by a power law (Γ ∼ 1.6), which can be interpreted as non-thermal emission from a relativistic jet. The source exhibits moderate flux variability on timescales of both months and years. Correlated brightness variations in the (0.5-2) keV and (2-10) keV bands are explained by a single variable spectral component, such as the one from the jet. A possible soft excess seen in the data from 2004 cannot be confirmed by the new XMM-Newton observations taken during low-flux states. Any contribution to the total flux in 2004 is less than 20% of the power-law component. The (0.5-10) keV luminosities of PKS 2004−447 are in the range of (0.5−2.7) × 10 44 erg s −1 . A comparison of the X-ray properties among the known γ-NLS1 galaxies shows that in four out of five cases the X-ray spectrum is dominated by a flat power law without intrinsic absorption. These objects are moderately variable in their brightness, while spectral variability is observed in at least two sources. The major difference across the X-ray spectra of γ-NLS1s is the luminosity, which spans a range of almost two orders of magnitude from 10 44 erg s −1 to 10 46 erg s −1 in the (0.5-10) keV band.

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An unbiased sample of bright southern compact steep spectrum and gigahertz peaked spectrum sources

Cited by 43 publications

References 71 publications

Discovery of H i gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder

Discovery of H i gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder

J1216+0709: A Radio Galaxy With Three Episodes of Agn Jet Activity

The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004−447

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