The novel Gaia Multi Peak (GMP) technique has proven to be able to successfully select dual and lensed AGN candidates at sub-arcsec separations. Both populations are important because dual AGNs ...represent one of the central, still largely untested, predictions of lamdaCDM cosmology, and compact lensed quasars allow to probe the central regions of the lensing galaxies. In this work, we present high spatial resolution spectroscopy of twelve GMP-selected systems. We use the the adaptive-optics assisted integral-field spectrograph MUSE at VLT to resolve each system and study the nature of each component. All the targets reveal the presence of two components confirming the GMP selection. We classify five targets as dual AGNs, two as lensed systems, and five as a chance alignment of a star and and AGN. Having separations between 0.30" and 0.86", these dual and lensed systems are, to date, among the most compact ever discovered at z >0.3. This is the largest sample of distant dual AGNs with sub-arcsec separations ever presented in a single paper.
We present the ALMA view of 11 main-sequence DSFGs, (sub-)millimeter selected in the GOODS-S field, and spectroscopically confirmed to be at the peak of Cosmic SFH (z = 2-3). Our study combines the ...analysis of galaxy SED with ALMA continuum and CO spectral emission, by using ALMA Science Archive products at the highest spatial resolution currently available for our sample (< 1 arcsec). We include galaxy multi-band images and photometry (in the optical, radio and X-rays) to investigate the interlink between dusty, gaseous and stellar components and the eventual presence of AGN. We use multi-band sizes and morphologies to gain an insight on the processes that lead galaxy evolution, e.g. gas condensation, star formation, AGN feedback. The 11 DSFGs are very compact in the (sub-)millimeter (median r(ALMA) = 1.15 kpc), while the optical emission extends tolarger radii (median r(H)/r(ALMA) = 2.05). CO lines reveal the presence of a rotating disc of molecular gas, but we can not exclude either the presence of interactions and/or molecular outflows. Images at higher (spectral and spatial) resolution are needed to disentangle from the possible scenarios. Most of the galaxies are caught in the compaction phase, when gas cools and falls into galaxy centre, fuelling the dusty burst of star formation and the growing nucleus. We expect these DSFGs to be the high-zstar-forming counterparts of massive quiescent galaxies. Some features of CO emission in three galaxies are suggestive of forthcoming/ongoing AGN feedback, that is thought to trigger the morphological transition from star-forming disks to ETGs.
In the nearby universe jets from AGN are observed to have a dramatic impact on their surrounding extragalactic environment. Their effect at the `cosmic noon' (z>1.5), the epoch when star formation ...and AGN activity peak, is instead much less constrained. Here we present a study of the giant (750 kpc) radio galaxy 103025+052430 located at the centre of a protocluster at redshift z=1.7, with a focus on its interaction with the external medium. We present new LOFAR observations at 144 MHz, which we combine with VLA 1.4 GHz and 0.5-7 keV Chandra archival data. The new map at 144 MHz confirms that the source has a complex morphology, possibly consistent with the `hybrid morphology' classification. The large size of the source gave us the possibility to perform a resolved radio spectral index analysis, a very unique opportunity for a source at such high redshift. This reveals a tentative flattening of the radio spectral index at the edge of the backflow in the Western lobe, which might be indicating plasma compression. The spatial coincidence between this region and the thermal X-ray bubble C suggests a causal connection between the two. Contrary to previous estimates for the bright X-ray component A, we find that inverse Compton scattering between the radio-emitting plasma of the Eastern lobe and the CMB photons can account for a large fraction (~45%-80%) of its total 0.5-7 keV measured flux. Finally, the X-ray bubble C, which is consistent with a thermal origin, is found to be significantly overpressurised with respect to the ambient medium. This suggests that it will tend to expand and release its energy in the surroundings, contributing to the overall intracluster medium heating. Overall, 103025+052430 gives us the chance to investigate the interaction between AGN jets and the surrounding gas in a system that is likely the predecessor of the rich galaxy clusters we all well know at z=0.
The Star Formation Rate Density (SFRD) history of the Universe is well
constrained up to redshift $z \sim 2$. At earlier cosmic epochs, the picture
has been largely inferred from UV-selected galaxies ...(e.g. Lyman-break galaxies,
LBGs). However, LBGs' inferred SFRs strongly depend on the assumed dust
extinction correction, which is not well-constrained at high-$z$, while
observations in the radio domain are not affected by this issue. In this work
we measure the SFRD from a 1.4 GHz-selected sample of $\sim$600 galaxies in the
GOODS-N field up to redshift $\sim 3.5$. We take into account the contribution
of Active Galactic Nuclei from the Infrared-Radio correlation. We measure the
radio luminosity function, fitted with a modified Schechter function, and
derive the SFRD. The cosmic SFRD shows a rise up to $z \sim 2$ and then an
almost flat plateau up to $z \sim 3.5$. Our SFRD is in agreement with the ones
from other FIR/radio surveys and a factor 2 higher than those from LBG samples.
We also estimate that galaxies lacking a counterpart in the HST/WFC3 H-band
($H$-dark) make up $\sim 25\%$ of the $\phi$-integrated SFRD relative to the
full sample at z $\sim 3.2$, and up to $58\%$ relative to LBG samples.
We report on ALMA observations of D1, a system at z~6.15 with stellar mass M_* ~ 10^7 M_sun containing globular cluster (GC) precursors, strongly magnified by the galaxy cluster MACS J0416.1-2403. ...Since the discovery of GC progenitors at high redshift, ours is the first attempt to probe directly the physical properties of their neutral gas through infrared observations. A careful analysis of our dataset, performed with a suitable procedure designed to identify faint narrow lines and which can test various possible values for the unknown linewidth value, allowed us to identify a 4-sigma tentative detection of CII emission with intrinsic luminosity L_CII=(2.9 +/- 1.4) 10^6 L_sun, one of the lowest values ever detected at high redshift. This study offers a first insight on previously uncharted regions of the L_CII-SFR relation. Despite large uncertainties affecting our measure of the star formation rate, if taken at face value our estimate lies more than 1 dex below the values observed in local and high redshift systems. Our weak detection indicates a deficiency of CII emission, possibly ascribed to various explanations, such as a low-density gas and/or a strong radiation field caused by intense stellar feedback, and a low metal content. From the non-detection in the continuum we derive constraints on the dust mass, with 3-sigma upper limit values as low as a few 10^4 M_sun, consistent with the values measured in local metal-poor galaxies.
Based on ALMA Band 3 observations of the CO(2-1) line transition, we report the discovery of three new gas-rich (M_H2 ~ 1.5-4.8 x 10^10 M_sun, SFRs in the range ~5-100 M_sun/yr) galaxies in an ...overdense region at z=1.7, that already contains eight spectroscopically confirmed members. This leads to a total of 11 confirmed overdensity members, within a projected distance of ~ 1.15 Mpc and in a redshift range of Dz = 0.012. Under simple assumptions, we estimate that the system has a total mass of >= 3-6 x 10^13 M_sun, and show that it will likely evolve into a >~ 10^14 M_sun cluster at z = 0. The overdensity includes a powerful Compton-thick Fanaroff-Riley type II (FRII) radio-galaxy, around which we discovered a large molecular gas reservoir (M_H2 ~ 2 x 10^11 M_sun). We fitted the FRII resolved CO emission with a 2-D Gaussian model with major (minor) axis of ~ 27 (~ 17) kpc, that is a factor of ~3 larger than the optical rest-frame emission. Under the assumption of a simple edge-on disk morphology, we find that the galaxy interstellar medium produces a column density towards the nucleus of ~ 5.5 x 10^23 cm^-2. Such a dense ISM may then contribute significantly to the total nuclear obscuration measured in the X-rays (N_(H,X) ~ 1.5 x 10^24 cm^-2) in addition to a small, pc-scale absorber around the central engine. The velocity map of this source unveils a rotational motion of the gas that is perpendicular to the radio-jets. The FRII is located at the center of the projected spatial distribution of the structure members, and its velocity offset from the peak of the redshift distribution is well within the structure's velocity dispersion. All this, coupled with the large amount of gas around the FRII, its stellar mass of ~ 3 x 10^11 M_sun, SFR of ~ 200-600 M_sun/yr, and powerful radio-to-X-ray emission, suggests that this source is the likely progenitor of the future brightest cluster galaxy.
In this paper we show an application of the Minimum Spanning Tree (MST) clustering method to the high-energy gamma-ray sky observed at energies higher than 10 GeV in 6.3 years by the Fermi-Large Area ...Telescope. We report the detection of 19 new high-energy gamma-ray clusters with good selection parameters whose centroid coordinates were found matching the positions of known BL Lac objects in the 5th Edition of the Roma-BZCAT catalogue. A brief summary of the properties of these sources is presented.
We report ALMA high-resolution observations of water emission lines \(p-{\rm{H_2O}} (2_{02}-1_{11}\)), \(o-{\rm{H_2O}} (3_{21}-3_{12})\), \(p-{\rm{H_2O}} (4_{22}-4_{13})\), in the strongly lensed ...galaxy HATLASJ113526.2-01460 at redshift z \(\sim\) 3.1. From the lensing-reconstructed maps of water emission and line profiles, we infer the general physical properties of the ISM in the molecular clouds where the lines arise. We find that the water vapor lines \(o-{\rm{H_2O}} (3_{21}-3_{12})\), \(p-{\rm{H_2O}} (4_{22}-4_{13})\) are mainly excited by FIR pumping from dust radiation in a warm and dense environment, with dust temperatures ranging from 70 K to \(\sim 100\) K, as suggested by the line ratios. The \(p-{\rm{H_2O}} (2_{02}-1_{11})\) line instead, is excited by a complex interplay between FIR pumping and collisional excitation in the dense core of the star-forming region. This scenario is also supported by the detection of the medium-level excitation of CO resulting in the line emission CO (J=8-7). Thanks to the unprecedented high resolution offered by the combination of ALMA capabilities and gravitational lensing, we discern the different phases of the ISM and locate the hot molecular clouds into a physical scale of \(\sim\) 500 pc. We discuss the possibility of J1135 hosting an AGN in its accretion phase. Finally, we determine the relation between the water emission lines and the total IR luminosity of J1135, as well as the SFR as a function of water emission intensities, comparing the outcomes to local and high-\(z\) galactic samples from the literature.
Obscured AGN represent a significant fraction of the entire AGN population, especially at high redshift (~70% at z=3--5). They are often characterized by the presence of large gas and dust reservoirs ...that are thought to sustain and possibly obscure vigorous star formation processes that make these objects shine at far-IR and sub-mm wavelengths. We exploit ALMA Cycle 4 observations of the continuum (~2.1mm) and high-J CO emission of a sample of six X-ray selected SMGs hosting an obscured AGN at z_spec>2.5 in the 7 Ms CDF-S. We measured the masses and sizes of the dust and molecular gas and we derived the gas density and column density on the basis of a uniform sphere geometry. Finally, we compared the measured column densities with those derived from the Chandra X-ray spectra. We detected both the continuum and line emission for three sources for which we measured both the flux density and size. For the undetected sources, we derived an upper limit on the flux density. We found that the detected galaxies are rich in gas and dust (molecular gas mass in the range <0.5 - 2.7 x 10^10 M_sun for {\alpha}_CO=0.8 and up to ~2 x 10^11~M_sun for {\alpha}_CO=6.5, and dust mass <0.9 - 4.9 x 10^8 M_sun) and compact (gas major axis 2.1-3.0 kpc, dust major axis 1.4-2.7 kpc). The column densities associated with the ISM are on the order of 10^(23-24) cm-2, which is comparable with those derived from the X-ray spectra. For the detected sources we also derived dynamical masses in the range 0.8 - 3.7 x 10^10 M_sun. We conclude that the ISM of high redshift galaxies can substantially contribute to nuclear obscuration up to the Compton-thick (>10^24 cm-2) regime. In addition, we found that all the detected sources show a velocity gradient reminding one rotating system, even though two of them show peculiar features in their morphology that can be associated with a chaotic, possibly merging, structure.
We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 5 observations of a galaxy at \(z=1.91\), GDS24569, in search of molecular gas in its vicinity via the C I ...\(^3\)P\(_1\)-\(^3\)P\(_0\) line. GDS24569 is a massive (\(\log M_*/M_\odot=11\)) passively evolving galaxy, and characterized by compact morphology with an effective radius of \(\sim0.5\) kpc. We apply two blind detection algorithms to the spectral data cubes, and find no promising detection in or around GDS24569 out to projected distance of \(\sim320\) kpc, while a narrow tentative line (\(4.1 \sigma\)) is identified at \(+1200\) km/s by one of the algorithms. From the non-detection of C I, we place a \(3\sigma\) upper limit on molecular hydrogen mass, \(\sim 7.1 \times 10^9 M_\odot\), which converts to an extremely low gas-to-stellar mass fraction, \(< 5 \%\). We conduct a spectral energy distribution modeling by including optical-to-far-infrared data, and find a considerably high (\(\sim0.1\%\)) dust-to-stellar mass ratio, \(\sim10\)-\(100\times\) higher than those of local early-type galaxies. In combination with a previous result of an insufficient number of surrounding satellite galaxies, it is suggested that GDS24569 is unlikely to experience significant size evolution via satellite mergers. We discuss possible physical mechanisms that quenched GDS24569.
