scholarly journals FR-type radio sources at 3 GHz VLA-COSMOS: Relation to physical properties and large-scale environment

2021 ◽  
Vol 648 ◽  
pp. A102
Author(s):  
E. Vardoulaki ◽  
E. F. Jiménez Andrade ◽  
I. Delvecchio ◽  
V. Smolčić ◽  
E. Schinnerer ◽  
...  
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Large Scale ◽  
Learning Algorithm ◽  
Control Sample ◽  
X Rays ◽  
Radio Luminosity ◽  
Radio Structure ◽  
X Ray ◽  
Jet Power

Context. Radio active galactic nuclei (AGN) are traditionally separated into two Fanaroff-Riley (FR) type classes, edge-brightened FRII sources or edge-darkened FRI sources. With the discovery of a plethora of radio AGN of different radio shapes, this dichotomy is becoming too simplistic in linking the radio structure to the physical properties of radio AGN, their hosts, and their environment. Aims. We probe the physical properties and large-scale environment of radio AGN in the faintest FR population to date, and link them to their radio structure. We use the VLA-COSMOS Large Project at 3 GHz (3 GHz VLA-COSMOS), with a resolution and sensitivity of 0.″75 and 2.3 μJy beam−1 to explore the FR dichotomy down to μJy levels. Methods. We classified objects as FRIs, FRIIs, or hybrid FRI/FRII based on the surface-brightness distribution along their radio structure. Our control sample was the jet-less/compact radio AGN objects (COM AGN), which show excess radio emission at 3 GHz VLA-COSMOS exceeding what is coming from star-formation alone; this sample excludes FRs. The largest angular projected sizes of FR objects were measured by a machine-learning algorithm and also by hand, following a parametric approach to the FR classification. Eddington ratios were calculated using scaling relations from the X-rays, and we included the jet power by using radio luminosity as a probe. Furthermore, we investigated their host properties (star-formation ratio, stellar mass, morphology), and we explore their incidence within X-ray galaxy groups in COSMOS, and in the density fields and cosmic-web probes in COSMOS. Results. Our sample is composed of 59 FRIIs, 32 FRI/FRIIs, 39 FRIs, and 1818 COM AGN at 0.03 ≤ z ≤ 6. On average, FR objects have similar radio luminosities (L3 GHz ∼ 1023 W Hz−1 sr−1), spanning a range of 1021−26 W Hz−1 sr−1, and they lie at a median redshift of z ∼ 1. The median linear projected size of FRIIs is 106.636.9238.2 kpc, larger than that of FRI/FRIIs and FRIs by a factor of 2−3. The COM AGN have sizes smaller than 30 kpc, with a median value of 1.71.54.7 kpc. The median Eddington ratio of FRIIs is 0.0060.0050.007, a factor of 2.5 less than in FRIs and a factor of 2 higher than in FRI/FRII. When the jet power is included, the median Eddington ratios of FRII and FRI/FRII increase by a factor of 12 and 15, respectively. FRs reside in their majority in massive quenched hosts (M* > 1010.5 M⊙), with older episodes of star-formation linked to lower X-ray galaxy group temperatures, suggesting radio-mode AGN quenching. Regardless of their radio structure, FRs and COM AGN are found in all types and density environments (group or cluster, filaments, field). Conclusions. By relating the radio structure to radio luminosity, size, Eddington ratio, and large-scale environment, we find a broad distribution and overlap of FR and COM AGN populations. We discuss the need for a different classification scheme, that expands the classic FR classification by taking into consideration the physical properties of the objects rather than their projected radio structure which is frequency-, sensitivity- and resolution-dependent. This point is crucial in the advent of current and future all-sky radio surveys.

scholarly journals Discovery of a galaxy overdensity around a powerful, heavily obscured FRII radio galaxy at z = 1.7: star formation promoted by large-scale AGN feedback?

2019 ◽  
Vol 632 ◽  
pp. A26 ◽  
Author(s):  
R. Gilli ◽  
M. Mignoli ◽  
A. Peca ◽  
R. Nanni ◽  
I. Prandoni ◽  
...  
Keyword(s):  
Star Formation ◽  
Adaptive Optics ◽  
Large Scale ◽  
Rest Frame ◽  
Radio Galaxy ◽  
Radial Distance ◽  
Relativistic Electrons ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering

We report the discovery of a galaxy overdensity around a Compton-thick Fanaroff–Riley type II (FRII) radio galaxy at z = 1.7 in the deep multiband survey around the z = 6.3 quasi-stellar object (QSO) SDSS J1030+0524. Based on a 6 h VLT/MUSE and on a 4 h LBT/LUCI observation, we identify at least eight galaxy members in this structure with spectroscopic redshift z = 1.687 − 1.699, including the FRII galaxy at z = 1.699. Most members are distributed within 400 kpc from the FRII core. Nonetheless, the whole structure is likely much more extended, as one of the members was serendipitously found at ∼800 kpc projected separation. The classic radio structure of the FRII itself extends for ∼600 kpc across the sky. Most of the identified overdensity members are blue, compact galaxies that are actively forming stars at rates of ∼8–60 M⊙ yr−1. For the brightest of them, a half-light radius of 2.2 ± 0.8 kpc at 8000 Å rest-frame was determined based on adaptive optics-assisted observations with LBT/SOUL in the Ks band. We do not observe any strong galaxy morphological segregation or concentration around the FRII core. This suggests that the structure is far from being virialized and likely constitutes the progenitor of a local massive galaxy group or cluster caught in its main assembly phase. Based on a 500 ks Chandra ACIS-I observation, we found that the FRII nucleus hosts a luminous QSO (L2 − 10 keV = 1.3 × 1044 erg s−1, intrinsic and rest-frame) that is obscured by Compton-thick absorption (NH = 1.5 ± 0.6 × 1024 cm−2). Under standard bolometric corrections, the total measured radiative power (Lrad ∼ 4 × 1045 erg s−1) is similar to the jet kinetic power that we estimated from radio observations at 150 MHz (Pkin = 6.3 × 1045 erg s−1), in agreement with what is observed in powerful jetted AGN. Our Chandra observation is the deepest so far for a distant FRII within a galaxy overdensity. It revealed significant diffuse X-ray emission within the region that is covered by the overdensity. In particular, X-ray emission extending for ∼240 kpc is found around the eastern lobe of the FRII. Four out of the six MUSE star-forming galaxies in the overdensity are distributed in an arc-like shape at the edge of this diffuse X-ray emission. These objects are concentrated within 200 kpc in the plane of the sky and within 450 kpc in radial separation. Three of them are even more concentrated and fall within 60 kpc in both transverse and radial distance. The probability of observing four out of the six z = 1.7 sources by chance at the edge of the diffuse emission is negligible. In addition, these four galaxies have the highest specific star formation rates of the MUSE galaxies in the overdensity and lie above the main sequence of field galaxies of equal stellar mass at z = 1.7. We propose that the diffuse X-rays originate from an expanding bubble of gas that is shock heated by the FRII jet, and that star formation is promoted by the compression of the cold interstellar medium of the galaxies around the bubble, which may be remarkable evidence of positive AGN feedback on cosmological scales. We emphasize that our conclusions about the feedback are robust because even assuming that the diffuse X-ray emission arises from inverse Compton scattering of photons of the cosmic microwave background by the relativistic electrons in the radio lobe, star formation may be promoted by the nonthermal pressure of the expanding lobe.

scholarly journals Extended X-ray emission in PKS 1718−649

2018 ◽  
Vol 612 ◽  
pp. L4 ◽  
Author(s):  
T. Beuchert ◽  
A. Rodríguez-Ardila ◽  
V. A. Moss ◽  
R. Schulz ◽  
M. Kadler ◽  
...  
Keyword(s):  
Large Scale ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Effective Area ◽  
Radio Spectrum ◽  
Host Galaxy ◽  
X Rays ◽  
Radio Structure ◽  
X Ray ◽  
Close Proximity

PKS 1718−649 is one of the closest and most comprehensively studied candidates of a young active galactic nucleus (AGN) that is still embedded in its optical host galaxy. The compact radio structure, with a maximal extent of a few parsecs, makes it a member of the group of compact symmetric objects (CSO). Its environment imposes a turnover of the radio synchrotron spectrum towards lower frequencies, also classifying PKS 1718−649 as gigahertz-peaked radio spectrum (GPS) source. Its close proximity has allowed the first detection of extended X-ray emission in a GPS/CSO source with Chandra that is for the most part unrelated to nuclear feedback. However, not much is known about the nature of this emission. By co-adding all archival Chandra data and complementing these datasets with the large effective area of XMM-Newton, we are able to study the detailed physics of the environment of PKS 1718−649. Not only can we confirm that the bulk of the ≲kiloparsec-scale environment emits in the soft X-rays, but we also identify the emitting gas to form a hot, collisionally ionized medium. While the feedback of the central AGN still seems to be constrained to the inner few parsecs, we argue that supernovae are capable of producing the observed large-scale X-ray emission at a rate inferred from its estimated star formation rate.

scholarly journals Multiwavelength morphological study of active galaxies

2019 ◽  
Vol 15 (S356) ◽  
pp. 295-298
Author(s):  
Betelehem Bilata-Woldeyes ◽  
Mirjana Pović ◽  
Zeleke Beyoro-Amado ◽  
Tilahun Getachew-Woreta ◽  
Shimeles Terefe
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Active Galaxies ◽  
Morphological Properties ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
Public Data

AbstractStudying the morphology of a large sample of active galaxies at different wavelengths and comparing it with active galactic nuclei (AGN) properties, such as black hole mass (MBH) and Eddington ratio (λEdd), can help us in understanding better the connection between AGN and their host galaxies and the role of nuclear activity in galaxy formation and evolution. By using the BAT-SWIFT hard X-ray public data and by extracting those parameters measured for AGN and by using other public catalogues for parameters such as stellar mass (M*), star formation rate (SFR), bolometric luminosity (Lbol), etc., we studied the multiwavelength morphological properties of host galaxies of ultra-hard X-ray detected AGN and their correlation with other AGN properties. We found that ultra hard X-ray detected AGN can be hosted by all morphological types, but in larger fractions (42%) they seem to be hosted by spirals in optical, to be quiet in radio, and to have compact morphologies in X-rays. When comparing morphologies with other galaxy properties, we found that ultra hard X-ray detected AGN follow previously obtained relations. On the SFR vs. stellar mass diagram, we found that although the majority of sources are located below the main sequence (MS) of star formation (SF), still non-negligible number of sources, with diverse morphologies, is located on and/or above the MS, suggesting that AGN feedback might have more complex influence on the SF in galaxies than simply quenching it, as it was suggested in some of previous studies.

scholarly journals Hard X-ray polarizer to enable simultaneous three-dimensional nanoscale imaging of magnetic structure and lattice strain

2016 ◽  
Vol 23 (5) ◽  
pp. 1210-1215 ◽  
Author(s):  
Jonathan Logan ◽  
Ross Harder ◽  
Luxi Li ◽  
Daniel Haskel ◽  
Pice Chen ◽  
...  
Keyword(s):  
Magnetic Circular Dichroism ◽  
Three Dimensional ◽  
Control Sample ◽  
Magnetic Ordering ◽  
X Rays ◽  
Diffractive Imaging ◽  
X Ray ◽  
Coherent Diffractive Imaging ◽  
Diffraction Patterns ◽  
A New Technique

Recent progress in the development of dichroic Bragg coherent diffractive imaging, a new technique for simultaneous three-dimensional imaging of strain and magnetization at the nanoscale, is reported. This progress includes the installation of a diamond X-ray phase retarder at beamline 34-ID-C of the Advanced Photon Source. The performance of the phase retarder for tuning X-ray polarization is demonstrated with temperature-dependent X-ray magnetic circular dichroism measurements on a gadolinium foil in transmission and on a Gd5Si2Ge2crystal in diffraction geometry with a partially coherent, focused X-ray beam. Feasibility tests for dichroic Bragg coherent diffractive imaging are presented. These tests include (1) using conventional Bragg coherent diffractive imaging to determine whether the phase retarder introduces aberrations using a nonmagnetic gold nanocrystal as a control sample, and (2) collecting coherent diffraction patterns of a magnetic Gd5Si2Ge2nanocrystal with left- and right-circularly polarized X-rays. Future applications of dichroic Bragg coherent diffractive imaging for the correlation of strain and lattice defects with magnetic ordering and inhomogeneities are considered.

scholarly journals A young and obscured AGN embedded in the giant radio galaxy Mrk 1498

2019 ◽  
Author(s):  
L Hernández-García ◽  
F Panessa ◽  
L Bassani ◽  
G Bruni ◽  
F Ursini ◽  
...  
Keyword(s):  
Large Scale ◽  
Radio Galaxy ◽  
Conclusive Evidence ◽  
X Rays ◽  
Nuclear Activity ◽  
X Ray ◽  
Multi Wavelength ◽  
Tidal Streams ◽  
A Minor ◽  
Extended Emission

Abstract Mrk 1498 is part of a sample of galaxies with extended emission line regions (extended outwards up to a distance of ∼7 kpc) suggested to be photo-ionized by an AGN that has faded away or that is still active but heavily absorbed. Interestingly, the nucleus of Mrk 1498 is at the center of two giant radio lobes with a projected linear size of 1.1 Mpc. Our multi-wavelength analysis reveals a complex nuclear structure, with a young radio source (Giga-hertz Peaked Spectrum) surrounded by a strong X-ray nuclear absorption, a mid-infrared spectrum that is dominated by the torus emission, plus a circum-nuclear extended emission in the [OIII] image (with radius of ∼ 1 kpc), most likely related to the ionization of the AGN, aligned with the small and large scale radio jet and extended also at X-rays. In addition a large-scale extended emission (up to ∼ 10 kpc) is only visible in [OIII]. These data show conclusive evidence of a heavily absorbed nucleus and has recently restarted its nuclear activity. To explain its complexity, we propose that Mrk 1498 is the result of a merging event or secular processes, such as a minor interaction, that has triggered the nuclear activity and produced tidal streams. The large-scale extended emission that gives place to the actual morphology could either be explained by star formation or outflowing material from the AGN.

scholarly journals A deep learning view of the census of galaxy clusters in IllustrisTNG

2020 ◽  
Vol 498 (4) ◽  
pp. 5620-5628
Author(s):  
Y Su ◽  
Y Zhang ◽  
G Liang ◽  
J A ZuHone ◽  
D J Barnes ◽  
...  
Keyword(s):  
Deep Learning ◽  
Galaxy Clusters ◽  
Large Scale ◽  
Learning Algorithm ◽  
X Ray ◽  
Deep Learning Algorithm ◽  
Cluster Evolution ◽  
Novel Method ◽  
Massive Clusters ◽  
Activation Mapping

ABSTRACT The origin of the diverse population of galaxy clusters remains an unexplained aspect of large-scale structure formation and cluster evolution. We present a novel method of using X-ray images to identify cool core (CC), weak cool core (WCC), and non-cool core (NCC) clusters of galaxies that are defined by their central cooling times. We employ a convolutional neural network, ResNet-18, which is commonly used for image analysis, to classify clusters. We produce mock Chandra X-ray observations for a sample of 318 massive clusters drawn from the IllustrisTNG simulations. The network is trained and tested with low-resolution mock Chandra images covering a central 1 Mpc square for the clusters in our sample. Without any spectral information, the deep learning algorithm is able to identify CC, WCC, and NCC clusters, achieving balanced accuracies (BAcc) of 92 per cent, 81 per cent, and 83 per cent, respectively. The performance is superior to classification by conventional methods using central gas densities, with an average ${\rm BAcc}=81{{\ \rm per\ cent}}$, or surface brightness concentrations, giving ${\rm BAcc}=73{{\ \rm per\ cent}}$. We use class activation mapping to localize discriminative regions for the classification decision. From this analysis, we observe that the network has utilized regions from cluster centres out to r ≈ 300 kpc and r ≈ 500 kpc to identify CC and NCC clusters, respectively. It may have recognized features in the intracluster medium that are associated with AGN feedback and disruptive major mergers.

scholarly journals A NuSTAR view of powerful γ-ray loud blazars

2019 ◽  
Vol 627 ◽  
pp. A72 ◽  
Author(s):  
G. Ghisellini ◽  
M. Perri ◽  
L. Costamante ◽  
G. Tagliaferri ◽  
T. Sbarrato ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Peak Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
Γ Ray ◽  
The Universe ◽  
Jet Power

We observed three blazars at z >  2 with the NuSTAR satellite. These were detected in the γ-rays by Fermi/LAT and in the soft X-rays, but have not yet been observed above 10 keV. The flux and slope of their X-ray continuum, together with Fermi/LAT data allows us to estimate their total electromagnetic output and peak frequency. For some of them we were able to study the source in different states, and investigate the main cause of the different observed spectral energy distribution. We then collected all blazars at redshifts greater than 2 observed by NuSTAR, and confirm that these hard and luminous X-ray blazars are among the most powerful persistent sources in the Universe. We confirm the relation between the jet power and the disk luminosity, extending it at the high-energy end.

scholarly journals Extragalactic X-Ray Sources

1973 ◽  
Vol 55 ◽  
pp. 199-207
Author(s):  
G. R. Burbidge
Keyword(s):  
Physical Properties ◽  
Compton Scattering ◽  
X Rays ◽  
X Ray ◽  
Thermal Bremsstrahlung

A review is given of the physical properties of extragalactic X-ray sources. The generation of X-rays as thermal bremsstrahlung, by the synchrotron mechanism or by Compton Scattering, is discussed. It is shown that each may be important depending on the circumstances. Only more detailed observations will enable us to decide which process dominates in any given source.

scholarly journals Starburst and post-starburst high-redshift protogalaxies

2019 ◽  
Vol 626 ◽  
pp. A85 ◽  
Author(s):  
Ellis R. Owen ◽  
Kinwah Wu ◽  
Xiangyu Jin ◽  
Pooja Surajbali ◽  
Noriko Kataoka
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
High Energy ◽  
Starburst Galaxies ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
High Energy Cosmic Rays ◽  
Radiation Fields ◽  
Inverse Compton

Quenching of star-formation has been identified in many starburst and post-starburst galaxies, indicating burst-like star-formation histories (SFH) in the primordial Universe. Galaxies undergoing violent episodes of star-formation are expected to be rich in high energy cosmic rays (CRs). We have investigated the role of these CRs in such environments, particularly how they could contribute to this burst-like SFH via quenching and feedback. These high energy particles interact with the baryon and radiation fields of their host via hadronic processes to produce secondary leptons. The secondary particles then also interact with ambient radiation fields to generate X-rays through inverse-Compton scattering. In addition, they can thermalise directly with the semi-ionised medium via Coulomb processes. Heating at a rate of ∼10−25 erg cm−3 s−1can be attained by Coulomb processes in a star-forming galaxy with one core-collapse SN event per decade, and this is sufficient to cause quenching of star-formation. At high-redshift, a substantial amount of CR secondary electron energy can be diverted into inverse-Compton X-ray emission. This yields an X-ray luminosity of above 1041 erg s−1by redshiftz = 7 which drives a further heating effect, operating over larger scales. This would be able to halt inflowing cold gas filaments, strangulating subsequent star-formation. We selected a sample of 16 starburst and post-starburst galaxies at 7 ≲ z ≲ 9 and determine the star-formation rates they could have sustained. We applied a model with CR injection, propagation and heating to calculate energy deposition rates in these 16 sources. Our calculations show that CR feedback cannot be neglected as it has the strength to suppress star-formation in these systems. We also show that their currently observed quiescence is consistent with the suffocation of cold inflows, probably by a combination of X-ray and CR heating.

scholarly journals X-ray studies of the structure of hair, wool, and related fibres.- I. General

1931 ◽  
Vol 230 (681-693) ◽  
pp. 75-101 ◽  
Keyword(s):  
Physical Properties ◽  
Crystalline Structure ◽  
Human Hair ◽  
X Rays ◽  
Present Communication ◽  
Cellulose Fibres ◽  
X Ray ◽  
Usual Manner ◽  
Wide Range ◽  
Muscle Nerve

It is now some ten years since it was first realised that, in common with natural and artificial cellulose fibres, animal fibres with a protein basis are in many cases sufficiently crystalline to yield a pronounced interference figure when examined with monochromatic X-rays. Such “ X-ray fibre diagrams ” were reported in 1921 by HERZOG and JANCKE* for muscle, nerve, sinew, and hair, and in 1924 similar photographs from human hair were obtained by one of the present writers. From an X-ray examination of wool it was concluded by THREADGOLD that “ there is no evidence for assuming the wool fibres and yarns examined to have a crystalline structure,” but in 1927 EWLES and SPEAKMAN had already obtained wool interference figures precisely similar to those previously obtained from hair. The two last-named authors endeavoured to interpret their results in the light of certain physical properties, but it has since become clear that the problem of hair structure is sufficiently complex to necessitate an X-ray study of a wide range of materials under as great a variety of conditions as possible. The present communication is an account of the preliminary results of such an investigation. Over a hundred X-ray photographs have been taken, using copper K-radiation filtered of the MATHS FORMULA line by nickel foil about 1/100 mm. thick. The “ slit” was a rectangular aperture, 4 cm. x 0.5mm., the scattered rays from which were screened off in the usual manner by a secondary slit.

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