Publications (80)
The cosmic X-ray background: abundance and evolution of hidden black holes
Roberto Gilli
The growth of supermassive black holes across cosmic time leaves a radiative imprint recorded in the X-ray background (XRB). The XRB spectral shape suggests that a large population…
The X-Ray Derived Cosmological Star Formation History and the Galaxy X-Ray Luminosity Functions in the Chandra Deep Fields North and South
Colin Norman, Andrew Ptak, Ann Hornschemeier +15
The cosmological star formation rate in the combined Chandra Deep Fields North and South is derived from our X-Ray Luminosity Function for Galaxies in these Deep Fields. Mild evolu…
Unresolved z~8 point sources and their impact on the bright end of the galaxy luminosity function
Yuzo Ishikawa, Takahiro Morishita, Massimo Stiavelli +7
The distribution and properties of the first galaxies and quasars are critical pieces of the puzzle in understanding galaxy evolution and cosmic reionization. Previous studies have…
Tracing AGN-Galaxy Co-Evolution with UV Line-Selected Obscured AGN
Luigi Barchiesi, Lucia Marchetti, Mattia Vaccari +11
Understanding black hole-galaxy co-evolution and the role of AGN feedback requires complete AGN samples, including heavily obscured systems. In this work, we present the first UV l…
X-Ray Properties of AGN in Brightest Cluster Galaxies. I.A Systematic Study of the Chandra Archive in the and Redshift Range
Lilan Yang, Paolo Tozzi, Heng Yu +5
We present a search for nuclear X-ray emission in the brightest cluster galaxies (BCGs) of a sample of groups and clusters of galaxies extracted from the Chandra archive. The exqui…
Unveil the nature of JWST-AGN and Little Red Dots with SKAO continuum surveys
Giovanni Mazzolari, Dharam V. Lal, Isabella Prandoni +6
The advent of JWST has revealed a large population of AGN at , which are dex more abundant than previously expected, including also the enigmatic population of Little…
Feedback effect on the observable properties of AGN
Fabio Vito, Fabio Di Mascia, Simona Gallerani +4
Active galactic nuclei (AGN) feedback has a major impact onto the supermassive black-hole (SMBH) growth, the properties of the host galaxies, and their cosmic evolution. We investi…
An X-ray fading, UV brightening QSO at
Fabio Vito, Marco Mignoli, Roberto Gilli +13
Explaining the existence of SMBHs at is a persistent challenge to modern astrophysics. Multi-wavelength observations of QSOs revea…
Rolling down from the 30 keV peak: modelling the hard X-ray and gamma-ray backgrounds
Andrea Comastri, Roberto Gilli, Guenther Hasinger
We will briefly discuss the importance of sensitive X-ray observations above a few tens of keV for a better understanding of the physical mechanisms associated to the Supermassive…
The Advanced X-ray Imaging Satellite (AXIS) Community Science Book
Michael Koss, Nafisa Aftab, Steven W. Allen +395
The AXIS Community Science Book represents the collective effort of 592 scientists worldwide to define the transformative science enabled by the Advanced X-ray Imaging Satellite (A…
The MUSE view of Lyman- nebulae in High redshift Radio Galaxies
Miguel Coloma Puga, Barbara Balmaverde, Alessandro Capetti +2
We present the results of VLT/MUSE integral field spectroscopic observations of the Ly emission nebulae associated with 11 high redshift () radio galaxies (HzRGs)…
Lower-Luminosity Obscured AGN Host Galaxies are Not Predominantly in Major-Merging Systems at Cosmic Noon
Erini Lambrides, Marco Chiaberge, Timothy Heckman +15
For over 60 years, the scientific community has studied actively growing central super-massive black holes (active galactic nuclei -- AGN) but fundamental questions on their genesi…
The XMM-Newton wide-field survey in the COSMOS field: V. Angular Clustering of the X-ray Point Sources
Takamitsu Miyaji, Giovanni Zamorani, Nico Cappelluti +9
We present the first results of the measurements of angular auto-correlation functions (ACFs) of X-ray point sources detected in the XMM-Newton observations of the 2 deg2 COSMOS fi…
Radio selection of heavily obscured AGN in the J1030 field: unraveling a missing Compton-thick population
Giovanni Mazzolari, Roberto Gilli, Marco Mignoli +21
We tested the effectiveness of radio selection to discover heavily obscured AGNs, particularly at high-z, and we measured their abundance for the first time from a radio perspectiv…
An X-ray Significantly Variable, Luminous, Type 2 Quasar at z = 2.99 with a Massive Host Galaxy
Xiurui Zhao, Stefano Marchesi, Marco Ajello +8
We present a comprehensive X-ray analysis and spectral energy distribution (SED) fitting of WISEA J171419.96+602724.6, an extremely luminous type 2 quasar at = 2.99. The source…
Little Red and Blue Dots: AGN-excited narrow lines, Lyman- emission, and resemblance to standard quasars
Sophia Geris, Roberto Maiolino, Xihan Ji +35
We present an analysis of a sample of 36 Little Red and Blue Dots (LRDs and LBDs) at , identified by JWST in the GOODS fields. While both categories are selected to ha…
JWST-discovered AGN: evidence for heavy obscuration in the type-2 sample from the first stacked X-ray detection
Andrea Comastri, Giorgio Lanzuisi, Fabio Vito +9
One of the most puzzling properties of the high-redshift AGN population recently discovered by JWST, including both broad-line and narrow-line sources, is their X-ray weakness. Wit…
Chandra reveals a luminous Compton-thick QSO powering a blob in a starbursting protocluster
Fabio Vito, William Nielsen Brandt, Bret Darby Lehmer +7
Galaxy clusters in the local universe descend from high-redshift overdense regions known as protoclusters. The large gas reservoirs and high rate of galaxy interaction in protoclus…
X-UDS: The Chandra Legacy Survey of the UKIDSS Ultra Deep Survey Field
Dale D. Kocevski, Guenther Hasinger, Murray Brightman +25
We present the X-UDS survey, a set of wide and deep Chandra observations of the Subaru-XMM Deep/UKIDSS Ultra Deep Survey (SXDS/UDS) field. The survey consists of 25 observations th…
Broadband spectral energy distributions of SDSS-selected quasars and of their host galaxies: intense activity at the onset of AGN feedback
Federico Bianchini, Giulio Fabbian, Andrea Lapi +3
We present the mean spectral energy distribution (SED) of a sample of optically selected quasars (QSOs) at redshifts of . To derive it, we exploit photometric inform…
Testing the paradigm: First spectroscopic evidence of a quasar-galaxy Mpc-scale association at cosmic dawn
Roberto Decarli, Marco Mignoli, Roberto Gilli +9
State-of-the-art models of massive black hole formation postulate that quasars at reside in extreme peaks of the cosmic density structure in the early universe. Even so, dire…
Too many or too massive? Investigating the high- demography of active SMBHs from JWST
Daniel Roberts, Francesco Shankar, Vieri Cammelli +12
Recent JWST observations have unveiled a numerous population of low-luminosity active galactic nuclei (AGN) at , with space densities roughly an order of magnitude above p…
JADES -- The Rosetta Stone of JWST-discovered AGN: deciphering the intriguing nature of early AGN
Ignas Juodžbalis, Xihan Ji, Roberto Maiolino +23
JWST has discovered a large population of Active Galactic Nuclei (AGN) at high redshift. Many of these newly discovered AGN have broad permitted lines (typically H), but are ex…
Compton-thick AGN in the NuSTAR Era X: Analysing seven local CT-AGN candidates
Dhrubojyoti Sengupta, Stefano Marchesi, Cristian Vignali +14
We present the broad-band X-ray spectral analysis (0.6-50 keV) of seven Compton-Thick active galactic nuclei (CT-AGN; line-of-sight, l.o.s., column density cm) ca…
The Dual Nature of GHZ9: Coexisting Active Galactic Nuclei and Star Formation Activity in a Remote X-ray Source at z = 10.145
Lorenzo Napolitano, Marco Castellano, Laura Pentericci +33
We present James Webb Space Telescope (JWST)/NIRSpec PRISM spectroscopic characterization of GHZ9 at z= 10.145 0.010, currently the most distant source detected by the Chandr…
Redshift identification of X-ray selected active galactic nuclei in the J1030 field: searching for large-scale structures and high-redshift sources
Stefano Marchesi, Marco Mignoli, Roberto Gilli +23
We publicly release the spectroscopic and photometric redshift catalog of the sources detected with Chandra in the field of the =6.3 quasar SDSS J1030+0525. This is currently th…
X-ray spectral analyses of AGNs from the 7Ms Chandra Deep Field-South survey: the distribution, variability, and evolution of AGN's obscuration
Teng Liu, Paolo Tozzi, Jun-Xian Wang +18
We present a detailed spectral analysis of the brightest Active Galactic Nuclei (AGN) identified in the 7Ms Chandra Deep Field South (CDF-S) survey over a time span of 16 years. Us…
Large-scale clustering of buried X-ray AGN: Trends in AGN obscuration and redshift evolution
Akke Viitanen, Viola Allevato, Alexis Finoguenov +4
In order to test active galactic nucleus (AGN) unification and evolutionary models, we measured the AGN clustering properties as a function of AGN obscuration defined in terms of h…
A big red dot at cosmic noon
Federica Loiacono, Roberto Gilli, Marco Mignoli +22
We report the discovery of a little red dot (LRD), dubbed BiRD ('big red dot'), at in the field around the quasar SDSSJ1030+0524. Using NIRCam images, we identifie…
X-ray Unveiling Events in a z~1.6 Active Galactic Nucleus in the 7 Ms Chandra Deep Field-South
Li-Ming Yu, Bin Luo, William N. Brandt +14
We investigate the extreme X-ray variability of a z = 1.608 active galactic nucleus in the 7 Ms Chandra Deep Field-South (XID 403), which showed two significant X-ray brightening e…
The web of the Giant: spectroscopic confirmation of a Large Scale Structure around the z=6.31 quasar SDSS J1030+0524
Marco Mignoli, Roberto Gilli, Roberto Decarli +14
We report on the spectroscopic confirmation of a large scale structure around the luminous, z=6.31 QSO SDSS~J1030+0524, that is powered by a billion solar mass black hole. The stru…
A quasar-galaxy merger at : black hole mass and quasar properties from the NIRSpec spectrum
Federica Loiacono, Roberto Decarli, Marco Mignoli +31
We present JWST/NIRSpec integral field data of the quasar PJ308-21 at . As shown by previous ALMA and HST imaging, the quasar has two companion sources, interacting with…
The case for super-Eddington accretion in JWST broad-line AGN during the first billion years
Erini Lambrides, Rebecca Larson, Kristen Garofali +23
A multitude of JWST studies reveal a surprising over-abundance of over-massive accreting super-massive black holes (SMBHs) -- leading to a deepening tension between theory and obse…
The spatial distribution of X-ray selected AGN in the Chandra deep fields: a theoretical perspective
Federico Marulli, Silvia Bonoli, Enzo Branchini +3
We study the spatial distribution of X-ray selected AGN in the framework of hierarchical co-evolution of supermassive black holes and their host galaxies and dark matter haloes. To…
An extended Lyman outflow from a radio galaxy at z=3.7?
Miguel Coloma Puga, Barbara Balmaverde, Alessandro Capetti +5
Spatially resolved observations of AGN host galaxies undergoing feedback processes are one of the most relevant avenues through which galactic evolution can be studied, given the l…
Identification of (high-redshift) AGN with WFXT: lessons from COSMOS and CDFS
Marcella Brusa, Roberto Gilli, Francesca Civano +3
The Wide Field X-ray Telescope (WFXT) will provide tens of millions of AGN, with more than 4x10^5 expected at z>3. Here we review the issues present in the identification of (large…
Fast SMBH growth in the SPT2349--56 protocluster at
Fabio Vito, William N. Brandt, Andrea Comastri +7
Protoclusters at are gas-rich regions characterized by high star-formation activity. The same physical properties that enhance star formation in protoclusters are also though…
The most luminous blue quasars at 3.0<z<3.3 -- III. LBT spectra and accretion parameters
Bartolomeo Trefoloni, Elisabeta Lusso, Emanuele Nardini +13
We present the analysis of the rest frame ultraviolet and optical spectra of 30 bright blue quasars at , selected to examine the suitability of AGN as cosmological probes.…
QSO obscuration at high redshift (): Predictions from the BlueTides simulation
Yueying Ni, Tiziana Di Matteo, Roberto Gilli +3
High- AGNs hosted in gas rich galaxies are expected to grow through significantly obscured accretion phases. This may limit or bias their observability. In this work, we use \te…
X-ray properties and obscured fraction of AGN in the J1030 Chandra field
Matilde Signorini, Stefano Marchesi, Roberto Gilli +13
The 500ks Chandra ACIS-I observation of the field around the quasar SDSS J1030+0524 is currently the 5th deepest extragalactic X-ray survey. The rich multi-band coverage o…
Strong environmental AGN enhancement among DSFGs in z > 2 protoclusters
Monica Natalia Isla Llave, Fabio Vito, Alberto Traina +17
Galaxy protoclusters (PCs) at z > 2 are dense regions in which cold gas availability and elevated galaxy interaction rates trigger intense, often dust-obscured, star formation. The…
What do HST and Chandra tell us about the jet and the nuclear region of the radio galaxy 3C270?
Marco Chiaberge, Roberto Gilli, F. Duccio Macchetto +2
The HST/STIS ultraviolet image of the FR I radio galaxy 3C270 shows the presence of a jet-like structure emerging from the position of the nucleus. This feature, which represents t…
Discovery of the first heavily obscured QSO candidate at in a close galaxy pair
Fabio Vito, William Nielsen Brandt, Franz Erik Bauer +14
While theoretical arguments predict that most of the early growth of supermassive black holes (SMBHs) happened during heavily obscured phases of accretion, current methods used for…
X-ray variability with WFXT: AGNs, transients and more
Maurizio Paolillo, Ciro Pinto, Viola Allevato +6
The Wide Field X-ray Telescope (WFXT) is a proposed mission with a high survey speed, due to the combination of large field of view (FOV) and effective area, i.e. grasp, and sharp…
Compton-Thick AGN in the NuSTAR era VII. A joint NuSTAR, Chandra and XMM-Newton analysis of two nearby, heavily obscured sources
Alberto Traina, Stefano Marchesi, Cristian Vignali +11
We present the joint Chandra, XMM-Newton and NuSTAR analysis of two nearby Seyfert galaxies, NGC 3081 and ESO 565-G019. These are the only two having Chandra data in a larger sampl…
Systematic search for lensed X-ray sources in the CLASH fields
Ang Liu, Paolo Tozzi, Piero Rosati +8
We search for unresolved X-ray emission from lensed sources in the FOV of 11 CLASH clusters with Chandra data. We consider the solid angle in the lens plane corresponding to a magn…
The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
Roberto Gilli, Andrea Comastri, Guenther Hasinger
We present a detailed and self-consistent modeling of the cosmic X-ray background (XRB) based on the most up-to-date X-ray luminosity functions (XLF) and evolution of Active Galact…
Narrow line AGN selection in CEERS: spectroscopic selection, physical properties, X-ray and radio analysis
Giovanni Mazzolari, Jan Scholtz, Roberto Maiolino +11
In this work, we spectroscopically select narrow-line AGNs (NLAGNs) among the ~300 publicly available medium-resolution spectra of the Cosmic Evolution Early Release Science Survey…
Measuring the Cosmic X-ray Background in 3-20keV with Straylight from NuSTAR
Steven Rossland, Daniel Wik, Brian Grefenstette +13
By characterizing the contribution of stray light to large datasets from the NuSTAR X-ray observatory collected over 2012--2017, we report a measurement of the cosmic X-ray backgro…
X-ray redshifts for obscured AGN: a case study in the J1030 deep field
Alessandro Peca, Cristian Vignali, Roberto Gilli +9
We present a procedure to constrain the redshifts of obscured ( cm) Active Galactic Nuclei (AGN) based on low-count statistics X-ray spectra, which can be ado…
No evidence for an Eddington-ratio dependence of X-ray weakness in BALQSOs
Fabio Vito, William Nielsen Brandt, Bin Luo +3
Several works have studied the relation between X-ray, UV, and wind properties in broad absorption line quasars (BALQSOs), generally concluding that the formation of strong winds i…
The near-infrared SED of blue quasars: what drives the evolution of the dusty torus?
Bartolomeo Trefoloni, Roberto Gilli, Elisabeta Lusso +5
A fundamental ingredient in the unified model of active galactic nuclei (AGN) is the obscuring torus, whose innermost, hottest region dominates the near infrared (NIR) emission. Ch…
Mock catalogs for the extragalactic X-ray sky: simulating AGN surveys with Athena and with the AXIS probe
Stefano Marchesi, Roberto Gilli, Giorgio Lanzuisi +8
We present a series of new, publicly available mock catalogs of X-ray selected active galactic nuclei (AGNs), non-active galaxies, and clusters of galaxies. They are based on up-to…
Compton-Thick AGN in the NuSTAR era VIII: A joint NuSTAR-XMM-Newton monitoring of the changing-look Compton-thick AGN NGC 1358
Stefano Marchesi, Xiurui Zhao, Núria Torres-Albà +18
We present the multi-epoch monitoring with NuSTAR and XMM-Newton of NGC 1358, a nearby Seyfert 2 galaxy whose properties made it a promising candidate X-ray changing look AGN, i.e.…
The Hard X-Ray Luminosity Function of High-Redshift () Active Galactic Nuclei
Fabio Vito, Roberto Gilli, Cristian Vignali +4
We present the hard-band () X-ray luminosity function (HXLF) of band selected AGN at high redshift. We have assembled a sample of 141 AGN…
The Chandra COSMOS legacy survey: Energy Spectrum of the Cosmic X-ray Background and constraints on undetected populations
Nico Cappelluti, Yanxia Li, Angelo Ricarte +15
Using {\em Chandra} observations in the 2.15 deg COSMOS legacy field, we present one of the most accurate measurements of the Cosmic X-ray Background (CXB) spectrum to date i…
LBT-MODS spectroscopy of high-redshift candidates in the Chandra J1030 field. A newly discovered z2.8 large scale structure
Stefano Marchesi, Marco Mignoli, Roberto Gilli +13
We present the results of a spectroscopic campaign with the Multi-Object Double Spectrograph (MODS) instrument mounted on the Large Binocular Telescope (LBT), aimed at obtaining a…
The most luminous blue quasars at 3.0<z<3.3. II. CIV/X-ray emission and accretion disc physics
Elisabeta Lusso, Emanuele Nardini, Susanna Bisogni +12
We analyse the properties of the CIV broad emission line in connection with the X-ray emission of 30 bright SDSS quasars at z~3.0-3.3 with pointed XMM-Newton observations, which we…
X-ray spectroscopy of the z=6.4 quasar J1148+5251
Simona Gallerani, Luca Zappacosta, Maria Carmela Orofino +9
We present the 78-ks Chandra observations of the quasar SDSS J1148+5251. The source is clearly detected in the energy range 0.3-7 keV with 42 counts (with a significance $\…
Heavily Obscured AGN detection: a Radio vs X-ray challenge
Giovanni Mazzolari, Roberto Gilli, Marcella Brusa +11
In this work, we study the AGN radio detection effectiveness in the major deep extragalactic surveys, considering different AGN obscuration levels, redshift, and AGN bolometric lum…
The deepest X-ray view of high-redshift galaxies: constraints on low-rate black-hole accretion
Fabio Vito, Roberto Gilli, Cristian Vignali +16
We exploit the 7 Ms \textit{Chandra} observations in the \chandra\,Deep Field-South (\mbox{CDF-S}), the deepest X-ray survey to date, coupled with CANDELS/GOODS-S data, to measure…
The Chandra COSMOS Survey, I: Overview and Point Source Catalog
Martin Elvis, Francesca Civano, Cristian Vignali +40
The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10h, +02deg) with an effective exp…
PACHA: Probing AGN Coronae with High-redshift AGN
Xiurui Zhao, Elias Kammoun, Marco Ajello +18
The X-ray emission of active galactic nuclei (AGN) is generally attributed to inverse Compton scattering of accretion-disk photons by hot electrons in a compact corona. In local AG…
The X-ray properties of quasars: no evident evolution of accretion physics in the first Gyr of the Universe
Fabio Vito, William Nielsen Brandt, Franz Erik Bauer +10
X-ray emission from QSOs has been used to assess SMBH accretion properties up to ~6. However, at only ~15 QSOs are covered by sensitive X-ray observations, preventing a st…
The GlimmIr: Spectroscopic Variability in a z~7 LRD Indicates Rapid Changes in Both the Narrow and Broad Line Regions
Erini Lambrides, Taylor A. Hutchison, Rebecca L. Larson +39
The enigmatic population of ``Little Red Dots'' (LRDs) sit at the center of some of the largest debates in extragalactic astronomy today. The source(s) of ionizing emission and the…
A quasar-galaxy merger at : rapid host growth via accretion of two massive satellite galaxies
Roberto Decarli, Federica Loiacono, Emanuele Paolo Farina +38
We present JWST/NIRSpec Integral Field Spectroscopy in the rest-frame optical bands of the system PJ308-21, a quasar at caught as its host galaxy interacts with companio…
The Iron Line Background
Marcella Brusa, Roberto Gilli, Andrea Comastri
We investigate the presence of iron line emission among faint X-ray sources identified in the 1Ms Chandra Deep Field South and in the 2Ms Chandra Deep Field North. Individual sourc…
Black hole accretion preferentially occurs in gas rich galaxies
Fabio Vito, Roberto Maiolino, Paola Santini +15
We have investigated the gas content of a sample of several hundred AGN host galaxies at z1 and compared it with a sample of inactive galaxies, matched in bins of stellar mass a…
JWST meets Chandra: a large population of Compton thick, feedback-free, and intrinsically X-ray weak AGN, with a sprinkle of SNe
Roberto Maiolino, Guido Risaliti, Matilde Signorini +22
We investigate the X-ray properties of a sample of 71 broad line and narrow line AGN at 2z11 discovered by JWST in the GOODS fields, which have the deepest Chandra observatio…
No evolution in the number density of little red dots from cosmic dawn to cosmic noon
Federica Loiacono, Roberto Gilli, Marco Mignoli +24
We present our search for little red dots (LRDs) in the "J1030 field", a region of the sky around the quasar SDSS J1030+0524, observed by the JWST EIGER program. Over 1…
Piercing Through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields: I. X-ray Spectral and Long-term Variability Analyses
Junyao Li, Yongquan Xue, Mouyuan Sun +13
We present a detailed X-ray spectral analysis of 1152 AGNs selected in the Chandra Deep Fields (CDFs), in order to identify highly obscured AGNs (…
A Large Population of Obscured AGN in Disguise as Low Luminosity AGN in Chandra Deep Field South
Erini Lambrides, Marco Chiaberge, Timothy Heckman +3
Population synthesis models of actively accreting super-massive black holes (or active galactic nuclei -- AGN) predict a large fraction that must grow behind dense, obscuring scree…
Intervening nuclear obscuration changing the X-ray look of the QSO CFHQS J164121+375520
Fabio Vito, William Nielsen Brandt, Andrea Comastri +16
X-ray observations of the optically selected QSO CFHQS J164121+375520 (hereafter J1641) revealed that its flux dropped by a factor from 2018, when it was a bri…
Relativistic Iron lines at high redshifts
Andrea Comastri, Marcella Brusa, Roberto Gilli
The shape and the intensity of the 6.4 keV iron line bring unique information on the geometrical and physical properties of the supermassive black hole and the surrounding accretin…
Proceedings of the "Wide Field X-ray Telescope" workshop
Piero Rosati, Stefano Borgani, Roberto Gilli +2
We list here the contents of the Proceedings of the "Wide Field X-ray Telescope" conference held in Bologna, Italy on 25-26 Nov 2009. The conference highlighted the scientific pote…
AGN in overdense environments at high- with AXIS
Fabio Vito, Paolo Tozzi, Roberto Gilli +3
Overdense regions at high redshift () are perfect laboratories to study the relations between environment and SMBH growth, and the AGN feedback processes on the surrou…
The nuclear SED of NGC6251: a BL Lac in the center of an FR I radio galaxy
Marco Chiaberge, Roberto Gilli, Alessandro Capetti +1
We determine the nuclear spectral energy distribution (SED) from the radio to the gamma-ray band for the FR I radio galaxy NGC6251, by using both data from the literature and analy…
The Advanced X-ray Imaging Satellite
Richard F. Mushotzky, James Aird, Amy J. Barger +41
Much of the baryonic matter in the Universe, including the most active and luminous sources, are best studied in the X-ray band. Key advances in X-ray optics and detectors have pav…
Chandra and Magellan/FIRE follow-up observations of PSO167-13: an X-ray weak QSO at
Fabio Vito, William Nielsen Brandt, Federica Ricci +19
The discovery of hundreds of QSOs in the first Gyr of the Universe powered by already grown SMBHs challenges our knowledge of SMBH formation. In particular, investigations of …
Radio Loud AGNs are Mergers
Marco Chiaberge, Roberto Gilli, Jennifer Lotz +1
We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei at z>1 using new samples. The objects have HST images taken with WFC3 in the IR channel.…