Host galaxies and environments of compact extragalactic radio sources

The main goal of this thesis is to study the interrelation of powerful radio sources with their hosts. The objects of study are GPS and CSS sources. Due to their small size, GPS/CSS sources are excellent probes of this relation. Furthermore, their young age allows us to compare them to the larger, old radio sources and establish a time-line evolution of this relation. This thesis combines imaging and spectroscopy of GPS/CSS sources at different wavelengths, and all our studies lead to the same conclusion: the presence and expansion of powerful radio sources clearly affect the properties and evolution of their hosts. All chapters of the thesis find evidence of strong interaction between the host and the radio source. Furthermore, the radio source and host can significantly affect each others evolution. However, this influence takes place in different ways. The influence that the host has on the radio source is somehow indirect. However it can completely change its destiny: depending of the contents, distribution and density of the gas, the radio source will die early, expand and grow into the large FR sources, or remain confined inside its host. In contrast, the influence of the radio source on its host seems to be more direct and takes place during its expansion through the host: the radio source will affect the kinematics and ionization of the emission line gas, and may change the star formation history of the host.Comment: Thesis dissertation. University of Groningen (The Netherlands) Full version available at: http://irs.ub.rug.nl/ppn/29144461

Radio Loud AGN in the 2XMMi catalogue

We are carrying out a search for all radio loud Active Galactic Nuclei observed with XMM-Newton, including targeted and field sources to perform a multi-wavelength study of these objects. We have cross-correlated the Veron-Cetty & Veron (2010) catalogue with the XMM-Newton Serendipitous Source Catalogue (2XMMi) and found about 4000 matched sources. A literature search provided radio, optical, and X-ray data for 403 sources. Here we summarize the first results of our study.Comment: Proceedings og the IAU275 Symposium: Jets at all scale

Correlation between X-ray and radio absorption in compact radio galaxies

Compact radio galaxies with a GHz-peaked spectrum (GPS) and/or compact-symmetric-object (CSO) morphology (GPS/CSOs) are increasingly detected in the X-ray domain. Their radio and X-ray emissions are affected by significant absorption. However, the locations of the X-ray and radio absorbers are still debated. We investigated the relationship between the column densities of the total ($N_{\mathrm{H}}$) and neutral ($N_{\mathrm{HI}}$) hydrogen to statistically constrain the picture. We compiled a sample of GPS/CSOs including both literature data and new radio data that we acquired with the Westerbork Synthesis Radio Telescope for sources whose X-ray emission was either established or under investigation. In this sample, we compared the X-ray and radio hydrogen column densities, and found that $N_{\mathrm{H}}$ and $N_{\mathrm{HI}}$ display a significant positive correlation, with $N_{\mathrm{HI}} \propto N_{\mathrm{H}}^b$, where $b=0.47$ and $b=0.35$, depending on the subsample. The $N_{\mathrm{H}}$ - $N_{\mathrm{HI}}$ correlation suggests that the X-ray and radio absorbers are either co-spatial or different components of a continuous structure. The correlation displays a large intrinsic spread that we suggest to originate from fluctuations, around a mean value, of the ratio between the spin temperature and the covering factor of the radio absorber, $T_{\rm s}/C_{\rm f}$.Comment: 18 pages, 5 figures, 6 tables; final version: a few typos corrected, minor style change

HST [Hubble Space Telescope]/STIS [Space Telescope Imaging Spectrograph] Low Dispersion Spectroscopy of Three Compact Steep Spectrum Sources: Evidence for Jet-Cloud Interaction

We present Hubble Space Telescope Imaging Spectrograph long-slit spectroscopy of the emission line nebulae in the compact steep spectrum radio sources 3C 67, 3C 277.1, and 3C 303.1. We derive BPT (Baldwin- Philips-Terlevich; Baldwin et al. 1981) diagnostic emission line ratios for the nebulae which are consistent with a mix of shock excitation and photoionization in the extended gas. In addition, line ratios indicative of lower ionization gas are found to be associated with higher gas velocities. The results are consistent with a picture in which these galaxy scale radio sources interact with dense clouds in the interstellar medium of the host galaxies, shocking the clouds thereby ionizing and accelerating them

A 3D Drizzle Algorithm for JWST and Practical Application to the MIRI Medium Resolution Spectrometer

We describe an algorithm for application of the classic `drizzle' technique to produce 3d spectral cubes using data obtained from the slicer-type integral field unit (IFU) spectrometers on board the James Webb Space Telescope. This algorithm relies upon the computation of overlapping volume elements (composed of two spatial dimensions and one spectral dimension) between the 2d detector pixels and the 3d data cube voxels, and is greatly simplified by treating the spatial and spectral overlaps separately at the cost of just 0.03% in spectrophotometric fidelity. We provide a matrix-based formalism for the computation of spectral radiance, variance, and covariance from arbitrarily dithered data and comment on the performance of this algorithm for the Mid-Infrared Instrument's Medium Resolution IFU Spectrometer (MIRI MRS). We derive a series of simplified scaling relations to account for covariance between cube spaxels in spectra extracted from such cubes, finding multiplicative factors ranging from 1.5 to 3 depending on the wavelength range and kind of data cubes produced. Finally, we discuss how undersampling produces periodic amplitude modulations in the extracted spectra in addition to those naturally produced by fringing within the instrument; reducing such undersampling artifacts below 1% requires a 4-point dithering strategy and spectral extraction radii of 1.5 times the PSF FWHM or greater.Comment: 16 pages, 12 figures. Revised version resubmitted to A

Jet-triggered star formation in young radio galaxies

Emission in the ultraviolet continuum is a salient signature of the hot, massive and consequently short-lived, stellar population that traces recent or ongoing star formation. With the aim of mapping star forming regions and morphologically separating the generic star formation from that associated with the galaxy-scale jet activity, we obtained high-resolution HST/UV imaging for a sample of nine compact radio sources. Out of these, seven are known Compact Steep Spectrum (CSS) galaxies that host young, kpc-scale radio sources and hence are the best candidates for studying radio-mode feedback on galaxy scales, while the other two form a control sample of larger sources. Extended UV emission regions are observed in six of the seven CSS sources showing close spatial alignment with the radio-jet orientation. If other mechanisms possibly contributing to the observed UV emission are ruled out, this could be evidence in support of jet-triggered star formation in the CSS phase of radio galaxy evolution.Comment: 4 pages, 2 figures, Proceedings of the 6th Workshop on GHz-Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) source

Optical- & UV-Continuum Morphologies of Compact Radio Source Hosts

We present the first systematic search for UV signatures from radio source-driven AGN feedback in Compact Steep Spectrum (CSS) radio galaxies. Owing to their characteristic sub-galactic jets (1-20 kpc projected linear sizes), CSS hosts are excellent laboratories for probing galaxy scale feedback via jet-triggered star formation. The sample consists of 7 powerful CSS galaxies, and 2 galaxies host to radio sources >20 kpc as control, at low to intermediate redshifts (z<0.6). Our new HST images show extended UV continuum emission in 6/7 CSS galaxies; with 5 CSS hosts exhibiting UV knots co-spatial and aligned along the radio-jet axis. Young (5 M$_\odot$) stellar populations are likely to be the dominant source of the blue excess emission in radio galaxies at these redshifts. Hence, the radio-aligned UV regions could be attributed to jet-induced starbursts. Lower near-UV SFRs compared to other indicators suggests low scattered AGN light contribution to the observed UV. Dust attenuation of UV emission appears unlikely from high internal extinction correction estimates in most sources. Comparison with evolutionary synthesis models shows that our observations are consistent with recent (~1-8 Myr old) star forming activity likely triggered by current or an earlier episode of radio emission, or by a confined radio source that has frustrated growth due to a dense environment. While follow-up spectroscopic and polarized light observations are needed to constrain the activity-related components in the observed UV, the detection of jet-induced star formation is a confirmation of an important prediction of the jet feedback paradigm.Comment: Submitted to Ap