The XXL Survey

Smolčić, Vernesa; Delhaize, J.; Huynh, Minh; Bondì, M.; Ciliegi, P.; Novak, Mladen; Baran, N.; Birkinshaw, Mark; Bremer, M. N.; Chiappetti, L.; Ferrari, C.; Fotopoulou, S.; Horellou, C.; McGee, Sean L.; Pacaud, F.; Pierre, M.; Raychaudhury, Somak; Röttgering, H. J. A.; Vignali, C.

doi:10.1051/0004-6361/201526818

Cited by 15 publications

(8 citation statements)

References 36 publications

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“…also Padovani et al 2015) is noticeable. In addition, the total counts (black) are in remarkable agreement with the observations by Prandoni et al (2017), Smolcic et al (2016) and Vernstrom et al (2016). We stress that at around S ∼ 0.5 mJy, a fraction of 1% of the counts is contributed by strongly, lensed high-redshift SFGs, whose identification by followup observations will be extremely important.…”

Section: Resultssupporting

confidence: 90%

Galaxy Evolution in the Radio Band: The Role of Star-forming Galaxies and Active Galactic Nuclei

Mancuso

Lapi

Prandoni

et al. 2017

ApJ

104

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We investigate the astrophysics of radio-emitting star-forming galaxies and active galactic nuclei (AGNs), and elucidate their statistical properties in the radio band including luminosity functions, redshift distributions, and number counts at sub-mJy flux levels, that will be crucially probed by next-generation radio continuum surveys. Specifically, we exploit the model-independent approach by Mancuso et al. (2016a,b) to compute the star formation rate functions, the AGN duty cycles and the conditional probability of a star-forming galaxy to host an AGN with given bolometric luminosity. Coupling these ingredients with the radio emission properties associated to star formation and nuclear activity, we compute relevant statistics at different radio frequencies, and disentangle the relative contribution of star-forming galaxies and AGNs in different radio luminosity, radio flux, and redshift ranges. Finally, we highlight that radio-emitting star-forming galaxies and AGNs are expected to host supermassive black holes accreting with different Eddington ratio distributions, and to occupy different loci in the galaxy main sequence diagrams. These specific predictions are consistent with current datasets, but need to be tested with larger statistics via future radio data with multi-band coverage on wide areas, as it will become routinely achievable with the advent of the SKA and its precursors.

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Section: Resultssupporting

confidence: 90%

Galaxy Evolution in the Radio Band: The Role of Star-forming Galaxies and Active Galactic Nuclei

Mancuso

Lapi

Prandoni

et al. 2017

ApJ

104

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“…The two fields have an extensive multiwavelength coverage from X-ray to radio wavelengths (the detailed descriptions are given in XXL Paper I and Fotopoulou et al 2016, hereafter XXL Paper VI 1 ). Baran et al (2016; hereafter XXL Paper IX) and Smolčić et al (2016; hereafter XXL Paper XI) presented radio observations of XXL with the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA), respectively. Butler et al (2018a, hereafter XXL Paper XVIII) reported the new observations of the full XXL-S with ATCA.…”

Section: The Xxl Survey and The Samplementioning

confidence: 99%

The XXL Survey

Мelnyk

Elyiv

Smolčić

et al. 2018

A&A

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Context. This work is part of a series of studies focusing on the environment and the properties of the X-ray selected active galactic nuclei (AGN) population from the XXL survey. The present survey, given its large area, continuity, extensive multiwavelength coverage, and large-scale structure information, is ideal for this kind of study. Here, we focus on the XXL-South (XXL-S) field. Aims. Our main aim is to study the environment of the various types of X-ray selected AGN and investigate its possible role in AGN triggering and evolution. Methods. We studied the large-scale (>1 Mpc) environment up to redshift z = 1 using the nearest neighbour distance method to compare various pairs of AGN types. We also investigated the small-scale environment (<0.4 Mpc) by calculating the local overdensities of optical galaxies. In addition, we built a catalogue of AGN concentrations with two or more members using the hierarchical clustering method and we correlated them with the X-ray galaxy clusters detected in the XXL survey. Results. It is found that radio detected X-ray sources are more obscured than non-radio ones, though not all radio sources are obscured AGN. We did not find any significant differences in the large-scale clustering between luminous and faint X-ray AGN, or between obscured and unobscured ones, or between radio and non-radio sources. At local scales (<0.4 Mpc), AGN typically reside in overdense regions, compared to non-AGN; however, no differences were found between the various types of AGN. A majority of AGN concentrations with two or more members are found in the neighbourhood of X-ray galaxy clusters within <25–45 Mpc. Our results suggest that X-ray AGN are typically located in supercluster filaments, but they are also found in over- and underdense regions.

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“…For XLSSC 634 in XXL-S, the image was taken from the BCS survey (Desai et al 2012) with the Mosaic2 imager on the Blanco 4 m telescope 5 . For radio data we used the NRAO VLA Sky Survey (Condon et al 1998) and Tasse et al (2008) for the XXL-N field and used Australia Telescope Compact Array (ATCA) data (Smolčić et al 2016 -also known as XXL Paper XI; Butler et al 2018 -also known as XXL Paper XVIII) for the XXL-S field (for XLSSC 634). We define an optical or radio source as a likely counterpart to a Chandra detected point source if it falls within 2 of the Chandra detected point source coordinates.…”

Section: Point Source Detection and Flux Calculationmentioning

confidence: 99%

The XXL Survey

Logan

Maughan

Bremer

et al. 2018

A&A

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Context. The XMM-XXL survey has used observations from the XMM-Newton observatory to detect clusters of galaxies over a wide range in mass and redshift. The moderate PSF (FWHM ~ 6″ on-axis) of XMM-Newton means that point sources within or projected onto a cluster may not be separated from the cluster emission, leading to enhanced luminosities and affecting the selection function of the cluster survey. Aims. We present the results of short Chandra observations of 21 galaxy clusters and cluster candidates at redshifts z > 1 detected in the XMM-XXL survey in X-rays or selected in the optical and infra-red. Methods. With the superior angular resolution of Chandra, we investigate whether there are any point sources within the cluster region that were not detected by the XMM-XXL analysis pipeline, and whether any point sources were misclassified as distant clusters. Results. Of the 14 X-ray selected clusters, 9 are free from significant point source contamination, either having no previously unresolved sources detected by Chandra or with less than about 10% of the reported XXL cluster flux being resolved into point sources. Of the other five sources, one is significantly contaminated by previously unresolved AGN, and four appear to be AGN misclassified as clusters. All but one of these cases are in the subset of less secure X-ray selected cluster detections and the false positive rate is consistent with that expected from the XXL selection function modelling. We also considered a further seven optically selected cluster candidates associated with faint XXL sources that were not classed as clusters. Of these, three were shown to be AGN by Chandra, one is a cluster whose XXL survey flux was highly contaminated by unresolved AGN, while three appear to be uncontaminated clusters. By decontaminating and vetting these distant clusters, we provide a pure sample of clusters at redshift z > 1 for deeper follow-up observations, and demonstrate the utility of using Chandra snapshots to test for AGN in surveys with high sensitivity but poor angular resolution.

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The XXL Survey

Cited by 15 publications

References 36 publications

Galaxy Evolution in the Radio Band: The Role of Star-forming Galaxies and Active Galactic Nuclei

Galaxy Evolution in the Radio Band: The Role of Star-forming Galaxies and Active Galactic Nuclei

The XXL Survey

The XXL Survey

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