INAF – OASOsservatorio di Astrofisica e Scienza dello Spazio di Bologna
The energy released by AGN has the potential to heat or remove the gas of the ISM, thus likely impacting the cold molecular gas reservoir of host galaxies at first, with star formation following on longer timescales. Previous works on high-z galaxies have yielded conflicting results, possibly due to selection biases and other systematics. To provide a reliable benchmark for galaxy evolution models at cosmic noon (z=1-3), two surveys were conceived: SUPER and KASHz, both targeting unbiased X-ray-selected AGN at z>1 that span a wide bolometric luminosity range. In this paper, we assess the effects of AGN feedback on the molecular gas content of host galaxies in a statistically robust, uniformly selected, coherently analyzed sample of AGN at z=1-2.6, drawn from the KASHz and SUPER surveys. By using ALMA data in combination with dedicated SED modeling, we retrieve CO and FIR luminosity as well as MM_* of SUPER and KASHz AGN. We selected non-active galaxies from PHIBBS, ASPECS and multiple ALMA/NOEMA surveys of sub-mm galaxies. By matching the samples in z, MM_* and LFIRL_{FIR}, we compared the properties of AGN and non-active galaxies within a Bayesian framework. We find that AGN hosts at given LFIRL_{FIR} are on average CO depleted compared to non-active galaxies, confirming what was previously found in the SUPER survey. Moreover, the molecular gas fraction distributions of AGN and non-active galaxies are statistically different, with that of of AGN being skewed to lower values. Our results indicate that AGN can indeed reduce the total cold molecular gas reservoir of their host galaxies. Lastly, by comparing our results with predictions from three cosmological simulations (TNG, Eagle and Simba) filtered to match the observed properties, we confirm already known discrepancies and highlight new ones between observations and simulations.[Abridged]
By combining Hubble Space Telescope (HST) and ground based optical and near-infrared photometric samples, we derive the RGB tip absolute magnitude of 22 galactic globular clusters (GGCs). The effects of varying the distance and the metallicity scales are also investigated. Then we compare the observed tip luminosities with those predicted by state-of-the-art stellar models that include the energy-loss due to the axion production in the degenerate core of red giant stars. We find that theoretical predictions including only the energy-loss by plasma neutrinos are, in general, in good agreement with the observed tip bolometric magnitudes, even though the latter are about 0.04 mag brighter, on the average. This small shift may be the result of systematic errors affecting the evaluation of the RGB tip bolometric magnitudes or, alternatively, it could be ascribed to an axion-electron coupling causing a non-negligible thermal production of axions. In order to estimate the strength of this possible axion sink, we perform a cumulative likelihood analysis using the RGB tips of the whole set of 22 GGCs. All the possible source of uncertainties affecting both the measured bolometric magnitudes and the corresponding theoretical predictions are carefully considered. As a result, we find that the value of the axion-electron coupling parameter that maximizes the likelihood probability is gae/10^13=0.60(+0.32;-0.58). This hint is valid, however, if the dominant energy sinks operating in the core of red giant stars are standard neutrinos and axions coupled with electrons. Any additional energy-loss process, not included in the stellar models, would reduce such a hint. Nevertheless, we find that values gae/10^13 > 1.48 can be excluded with a 95% of confidence.
We present ClumPyLen, a Python-based simulator designed to produce realistic mock observations of strongly lensed, high-redshift, clumpy star-forming galaxies. The tool models galaxy components such as disks, bulges, and spiral arms using Sérsic profiles, and it populates them with stellar clumps whose properties are sampled from physically motivated distributions. ClumPyLen includes the effects of gravitational lensing through user-provided deflection angle maps and simulates realistic observational conditions by accounting for instrumental effects, Point-Spread-Function convolution, sky background, and photon noise. The simulator can support a wide range of filters and instruments; here we focus on HST/ACS, HST/WFC3-IR, and JWST/NIRCam. We demonstrate the capabilities of the code through two examples, including a detailed simulation of the z = 6.145 source Cosmic Archipelago lensed by MACS J0416.1-2403. The simulated images closely match the morphology and limiting magnitudes of real observations. ClumPyLen is designed to explore the detectability of stellar clumps in terms of mass and size, especially in the low-mass regime, and it allows the study of clump blending effects. Thanks to its modular design, the code is highly adaptable to a wide range of scientific goals, including lensing studies, galaxy evolution, and the generation of synthetic datasets for machine learning or forward modeling applications.
A multitude of JWST studies reveal a surprising over-abundance of over-massive accreting super-massive blackholes (SMBHs) -- leading to a deepening tension between theory and observation in the first billion years of cosmic time. Across X-ray to infrared wavelengths, models built off of pre-JWST predictions fail to easily reproduce observed AGN signatures (or lack thereof), driving uncertainty around the true nature of these sources. Using a sample of JWST AGN identified via their broadened Halpha emission and covered by the deepest X-ray surveys, we find neither any measurable X-ray emission nor any detection of high-ionization emission lines frequently associated with accreting SMBHs. We propose that these sources are accreting at or beyond the Eddington limit, which reduces the need for efficient production of heavy SMBH seeds at cosmic dawn. Using a theoretical model of super-Eddington accretion, we can produce the observed relative dearth of both X-ray and ultraviolet emission, as well as the high Balmer decrements, without the need for significant dust attenuation. This work indicates that super-Eddington accretion is easily achieved through-out the early Universe, and further study is required to determine what environments are required to trigger this mode of black hole growth.
We present a sample of 1956 individual stellar clumps at redshift 0.73, reflecting the rapid increase towards the peak of the cosmic star formation history. We conclude that the results achieved over the studied redshift range are in agreement with expectation of in-situ clump formation scenario from large-scale disk fragmentation.
We present a comprehensive search and analysis of high-redshift galaxies in a suite of nine public JWST extragalactic fields taken in Cycle 1, covering a total effective search area of 358arcmin2\sim358{\rm arcmin^2}. Through conservative (8σ8\sigma) photometric selection, we identify 341 galaxies at 51.5σ51.5\,\sigma below the derived size-mass slope. These compact sources exhibit a high star formation surface density \Sigma_{\rm SFR}>10\,M_\odot\,{\rm yr^{-1}\,kpc^{-2}}, a range in which only <0.01\,\% of the local star-forming galaxy sample is found. For those with available NIRSpec data, no evidence of ongoing supermassive black hole accretion is observed. A potential explanation for the observed high [OIII]-to-Hbeta ratios could be high shock velocities, likely originating within intense star-forming regions characterized by high ΣSFR\Sigma_{\rm SFR}. Lastly, we find that the rest-frame UV and optical sizes of our sample are comparable. Our results are consistent with these early galaxies building up their structures inside-out and yet to exhibit the strong color gradient seen at lower redshift.
The study of resonant oscillation modes in low-mass red giant branch stars enables their ages to be inferred with exceptional (\sim10%) precision, unlocking the possibility to reconstruct the temporal evolution of the Milky Way at early cosmic times. Ensuring the accuracy of such a precise age scale is a fundamental yet difficult challenge. Since the age of red giant branch stars primarily hinges on their mass, an independent mass determination for an oscillating red giant star provides the means for such assessment. We analyze the old eclipsing binary KIC10001167, which hosts an oscillating red giant branch star and is a member of the thick disk of the Milky Way. Of the known red giants in eclipsing binaries, this is the only member of the thick disk that has asteroseismic signal of high enough quality to test the seismic mass inference at the 2% level. We measure the binary orbit and obtain fundamental stellar parameters through combined analysis of light curve eclipses and radial velocities, and perform a detailed asteroseismic, photospheric, and Galactic kinematic characterization of the red giant and binary system. We show that the dynamically determined mass 0.9337±0.0077 M0.9337\pm0.0077 \rm\ M_{\odot} (0.8%) of this 10 Gyr-old star agrees within 1.4% with the mass inferred from detailed modelling of individual pulsation mode frequencies (1.6%). This is now the only thick disk stellar system, hosting a red giant, where the mass has been determined both asteroseismically with better than 2% precision, and through a model-independent method at 1% precision, and we hereby affirm the potential of asteroseismology to define an accurate age scale for ancient stars to trace the Milky Way assembly history.
We present measurements of the gas-phase Oxygen and Nitrogen abundances obtained by applying the direct method to JWST NIRspec R1000R\sim1000 spectroscopy for 6 galaxies at redshift greater than 3. Our measurements are based on rest-frame optical Nitrogen [N II]λλ6548,6583_{\lambda\lambda6548,6583} lines and are complemented by 6 additional objects from the literature at 3z63\leq z \leq 6. We find that 9 out of 12 objects have values of log(N/O) that are compatible with those found for low-redshift, metal-poor, dwarf galaxies and for HII regions of more luminous local galaxies. However, 3 out of 12 objects have log(N/O) values that are overabundant compared to what is expected on the basis of their Oxygen abundance. We explore a few standard scenarios to explain the observations and conclude that, within the limited statistics available to us, none of them can be definitely excluded even though we prefer dilution by pristine gas infall in between star formation bursts as this is predicted by simulations to take place as a natural part of bursty star formation.
It has been known for decades that the observed number of baryons in the local universe falls about 30-40% short of the total number of baryons predicted by Big-Bang Nucleosynthesis, as inferred from density fluctuations of the Cosmic Microwave Background and seen during the first 2-3 billion years of the universe in the so called Lyman-alpha Forest. A theoretical solution to this paradox locates the missing baryons in the hot and tenuous filamentary gas between galaxies, known as the warm-hot intergalactic medium. However, it is difficult to detect them there because the largest by far constituent of this gas - hydrogen - is mostly ionized and therefore almost invisible in far-ultraviolet spectra with typical signal-to-noise ratios. Indeed, despite the large observational efforts, only a few marginal claims of detection have been made so far. Here we report observations of two absorbers of highly ionized oxygen (OVII) in the high signal-to-noise-ratio X-ray spectrum of a quasar at redshift >0.4. These absorbers show no variability over a 2-year timescale and have no associated cold absorption, making the assumption that they originate from the quasar's intrinsic outflow or the host galaxy's interstellar medium implausible. The OVII systems lie in regions characterized by large (x4 compared to average) galaxy over-densities and their number (down to the sensitivity threshold of our data), agrees well with numerical simulation predictions for the long-sought warm-hot intergalactic medium (WHIM). We conclude that the missing baryons have been found.
We designed customized Lyman-break color selection techniques to identify galaxy candidates in the redshift ranges 15z2015 \leq z \leq 20 and $20 \leq z \leq 28$. The selection was performed on the ASTRODEEP-JWST multi-band catalogs of the CEERS, Abell-2744, JADES, NGDEEP, and PRIMER survey fields, covering a total area of 0.2\sim0.2 sq. deg. We identify nine candidates at $15 \leq z \leq 20,whilenoobjectsarefoundbasedonthe, while no objects are found based on the z\gtrsim20$ color selection criteria. Despite exhibiting a >1.5 mag break, all the objects display multimodal redshift probability distributions across different SED-fitting codes and methodologies. The alternative solutions correspond to poorly understood populations of low-mass quiescent or dusty galaxies at z\sim3-7. This conclusion is supported by the analysis of a NIRSpec spectrum recently acquired by the CAPERS program for one interloper object, which is confirmed to be a dusty (E(BV)=0.8E(B-V)=0.8 mag) starburst galaxy at z=6.56z=6.56. We measured the UV luminosity function under different assumptions on the contamination level within our sample. We find that if even a fraction of the candidates is indeed at z15z\gtrsim15, the resulting UV LF points to a very mild evolution compared to estimates at z<15, implying a significant tension with existing theoretical models. In particular, confirming our bright (M_{\text{UV}}<-21) candidates would require substantial revisions to the theoretical framework. In turn, if all these candidates will be confirmed to be interlopers, we conclude that future surveys may need ten times wider areas to select MUV20M_{\text{UV}}\lesssim-20 galaxies at z>15. Observations in the F150W and F200W filters at depths comparable to those in the NIRCam LW bands are also required to mitigate contamination from rare red objects at z\lesssim8.
California Institute of Technology logoCalifornia Institute of TechnologyUniversity of OsloINFN Sezione di NapoliChinese Academy of Sciences logoChinese Academy of SciencesUniversity of ZurichUniversity of Oxford logoUniversity of OxfordUniversity of BonnUniversity of Michigan logoUniversity of MichiganUniversity of EdinburghETH Zürich logoETH ZürichCSICUniversity of Minnesota logoUniversity of MinnesotaUniversité Paris-Saclay logoUniversité Paris-SaclayHelsinki Institute of PhysicsStockholm University logoStockholm UniversityUniversity of HelsinkiUniversity of BolognaCEA logoCEAUniversity of GenevaUniversity of PortsmouthNASA Jet Propulsion LaboratoryUniversity of SussexUniversity of FlorenceNiels Bohr InstituteUniversity of PadovaEuropean Space AgencyEuropean Southern Observatory logoEuropean Southern ObservatoryEötvös Loránd UniversityCNESUniversity of LisbonUniversidad de ValparaísoUniversity of KwaZulu-NatalLudwig-Maximilians-UniversitätRoma Tre UniversityKapteyn Astronomical InstituteUniversity of BarcelonaMax Planck Institute for AstronomyLaboratoire d’Astrophysique de MarseilleINAF – Osservatorio Astronomico di RomaInstitut d'Astrophysique de ParisInstitut d’Estudis Espacials de Catalunya (IEEC)INFN - Sezione di PadovaIFPUINAF-IASF MilanoInstitute of Space ScienceDTU SpaceINFN-Sezione di BolognaKonkoly ObservatoryOsservatorio di Astrofisica e Scienza dello Spazio di BolognaParis ObservatoryUKATCAstronomical Observatory of BelgradeAix Marseille University, CNRS, CNESItalian National Institute for AstrophysicsKavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of TokyoAPC, CNRS, University Paris Diderot, Sorbonne Paris CitéINAF-Osservatorio Astronomico di NapoliINFN-Sezione di Roma TreUniversit de ToulouseINAF Osservatorio Astronomico di CapodimonteUniversit de LyonINAF Osservatorio Astrofisico di ArcetriINAF Osservatorio Astronomico di PadovaUniversity of Naples “Federico II”INAF Osservatorio di Astrofisica e Scienza dello Spazio di BolognaINAF ` Osservatorio Astronomico di Trieste
We investigate the cosmological constraints that can be expected from measurement of the cross-correlation of galaxies with cosmic voids identified in the Euclid spectroscopic survey, which will include spectroscopic information for tens of millions of galaxies over 1500015\,000 deg2^2 of the sky in the redshift range 0.9\leq z<1.8. We do this using simulated measurements obtained from the Flagship mock catalogue, the official Euclid mock that closely matches the expected properties of the spectroscopic data set. To mitigate anisotropic selection-bias effects, we use a velocity field reconstruction method to remove large-scale redshift-space distortions from the galaxy field before void-finding. This allows us to accurately model contributions to the observed anisotropy of the cross-correlation function arising from galaxy velocities around voids as well as from the Alcock-Paczynski effect, and we study the dependence of constraints on the efficiency of reconstruction. We find that Euclid voids will be able to constrain the ratio of the transverse comoving distance DMD_{\rm M} and Hubble distance DHD_{\rm H} to a relative precision of about 0.3%0.3\%, and the growth rate fσ8f\sigma_8 to a precision of between 5%5\% and 8%8\% in each of four redshift bins covering the full redshift range. In the standard cosmological model, this translates to a statistical uncertainty ΔΩm=±0.0028\Delta\Omega_\mathrm{m}=\pm0.0028 on the matter density parameter from voids, better than can be achieved from either Euclid galaxy clustering and weak lensing individually. We also find that voids alone can measure the dark energy equation of state to 6%6\% precision.
The second Gaia data release (DR2), contains very precise astrometric and photometric properties for more than one billion sources, astrophysical parameters for dozens of millions, radial velocities for millions, variability information for half a million of stellar sources and orbits for thousands of solar system objects. Before the Catalogue publication, these data have undergone dedicated validation processes. The goal of this paper is to describe the validation results in terms of completeness, accuracy and precision of the various Gaia DR2 data. The validation processes include a systematic analysis of the Catalogue content to detect anomalies, either individual errors or statistical properties, using statistical analysis, and comparisons to external data or to models. Although the astrometric, photometric and spectroscopic data are of unprecedented quality and quantity, it is shown that the data cannot be used without a dedicated attention to the limitations described here, in the Catalogue documentation and in accompanying papers. A particular emphasis is put on the caveats for the statistical use of the data in scientific exploitation.
In this data release from the LOFAR Two-metre Sky Survey (LoTSS) we present 120-168MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44^\circ30' and 1h00m +28^\circ00' and spanning 4178 and 1457 square degrees respectively. The images were derived from 3,451hrs (7.6PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4,396,228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 6" resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144MHz have: a median rms sensitivity of 83μ\muJy/beam; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2"; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8mJy/beam. By creating three 16MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of +/-0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 20" resolution 120-168MHz continuum images have a median rms sensitivity of 95μ\muJy/beam, and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480 x 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8mJy/beam at 4' and 2.2mJy/beam at 20"; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data.
We present a new method to determine the star formation rate (SFR) density of the Universe at z5z \gtrsim 5 that includes the contribution of dust-obscured star formation. For this purpose, we use a [CII] (158 μ\mum) selected sample of galaxies serendipitously identified in the fields of known z4.5z\gtrsim 4.5 objects to characterize the fraction of obscured SFR. The advantage of a [CII] selection is that our sample is SFR-selected, in contrast to a UV-selection that would be biased towards unobscured star formation. We obtain a sample of 23 [CII] emitters near star-forming (SF) galaxies and QSOs -- three of which we identify for the first time -- using previous literature and archival ALMA data. 18 of these serendipitously identified galaxies have sufficiently deep rest-UV data and are used to characterize the obscured fraction of the star formation in galaxies with SFRs 30 M yr1\gtrsim 30\ \text{M}_{\odot} \ \text{yr}^{-1}. We find that [CII] emitters identified around SF galaxies have \approx63\% of their SFR obscured, while [CII] emitters around QSOs have \approx93\% of their SFR obscured. By forward modeling existing wide-area UV luminosity function (LF) determinations, we derive the intrinsic UV LF using our characterization of the obscured SFR. Integrating the intrinsic LF to MUVM_{UV} = -20 we find that the obscured SFRD contributes to >3%>3\% and >10%>10\% of the total SFRD at z5z \sim 5 and z6z \sim 6 based on our sample of companions galaxies near SFGs and QSOs, respectively. Our results suggest that dust obscuration is not negligible at z5z\gtrsim 5, further underlining the importance of far-IR observations of the z5z\gtrsim 5 Universe.
The interaction between radio-jets and quasar host galaxies plays a paramount role in quasar/galaxy co-evolution. However, very little has been known so far about this interaction at very high-z. Here, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 7 and Band 3 of six radio-loud quasars' host galaxies at z>5z > 5. We recover [CII] 158 μ\mum line and underlying dust continuum emission at >2σ>2\sigma for five sources, while we obtain upper limits for the CO(6-5) emission line and continuum for the remaining source. At the spatial resolution of our observations (\sim1.0"-1.4"), we do not recover perturbed/extended morphologies or kinematics, signatures of potential mergers. These galaxies already host large quantities of gas, with [CII]-based star formation rates of 30400M30-400 M_{\odot} yr1^{-1}. Building their radio/sub-mm spectral energy distributions (SEDs), we find that in at least four cases the 1mm continuum intensity arises from a combination of synchrotron and dust emission, with an initial estimation of synchrotron contribution at 300 GHz of \gtrsim10%. We compare the properties of the sources inspected here with a large collection of radio-quiet sources from the literature, as well as a sample of radio-loud quasars from previous studies, at comparable redshift. We recover a potential mild decrease in L[CII]L_{\rm [CII]} for the radio-loud sources, which might be due to a suppression of the cool gas emission due to the radio-jets. We do not find any [CII]-emitting companion galaxy candidate around the five radio-loud quasars observed in Band 7: given the depth of our dataset, this result is still consistent with that observed around radio-quiet quasars. Further higher-spatial resolution observations, over a larger frequency range, of high-z radio-loud quasars hosts will allow for a better understanding of the physics of such sources.
The mechanisms of Lyα\alpha photon escape are key to understanding galaxy evolution and cosmic reionization, yet remain poorly understood. We investigate the UV-continuum sizes of 23 Lyα\alpha emitters (LAEs) at Cosmic Noon (1.7 < z < 3.3), extending previous size analyses to include fainter galaxies (MUV14M_{\rm UV} \simeq -14) using gravitational lensing. Our results show that these LAEs are unusually small for their luminosity, with a mean effective radius (reffr_{\rm eff}) of 170±140170 \pm 140 pc. They follow a distinct size-luminosity relation, with an intercept at MUV=21M_{\rm UV} = -21 approximately three times smaller than typical star-forming galaxies (SFGs) at similar redshifts. This relation, however, is consistent with that of low-redshift Green Pea galaxies, suggesting that LAEs maintain compact sizes across redshifts. We also find that Lyα\alpha equivalent width (EW(Lyα\alpha)) increases with decreasing reffr_{\rm eff}, confirming previous findings. The small sizes of LAEs lead to high star formation surface densities (Σ\SigmaSFR =1600M\sun yr1 kpc2= 1-600 M_{\sun} \ \rm{yr}^{-1} \ \rm{kpc^{-2}}), clearly separating them from typical SFGs in the Σ\SigmaSFR vs. reffr_{\rm eff} space. Given that high Σ\SigmaSFR is linked to strong galactic outflows, our findings imply that compact morphology plays a key role in Lyα\alpha escape, likely facilitated by outflows that clear under-dense channels in the ISM. Thus, these results demonstrate that compact size and high Σ\SigmaSFR can help identify Lyα\alpha-emitters.
Lyα\alpha emission is the strongest tracer of recombining ionized hydrogen in young, star-forming galaxies, but its origin is still debated. Lyα\alpha arises when emitted photons scatter in neutral hydrogen and, so far, observational efforts have mostly focused on the Lyα\alpha surface brightness and spectral profile, which depend on the neutral hydrogen column density, geometry, kinematics, powering mechanism and on the region from which the photons are emitted. Different processes produce similar spectra, but have different degrees of polarization, that we can use to discriminate between them. In this paper, we present the first spectropolarimetric observations of a typical star-forming galaxy at z3.4z\sim 3.4, strongly lensed by the cluster of galaxies Abell 2895, taken with the PMOS mode of the VLT/FORS2 instrument. We measure a Lyα\alpha degree of polarization 1σ1\sigma upper limit of 4.6%4.6\%. We develop new Lyα\alpha radiative transfer models to reproduce the observations, that can be explained by assuming the star-forming galaxy being embedded in a CGM with a biconical outflow geometry, with an opening angle of the wind θo,Wind30\theta_{o,Wind}\sim 30^\circ for line-of-sight angles θLOS20\theta_{LOS} \leq 20^\circ, θo,Wind45\theta_{o,Wind}\sim 45^\circ for θLOS20\theta_{LOS}\leq 20^\circ, θo,Wind60\theta_{o,Wind}\sim 60^\circ for θLOS20\theta_{LOS}\leq 20^\circ, and θo,Wind75\theta_{o,Wind}\sim 75^\circ for θLOS40\theta_{LOS}\leq 40^\circ, where θLOS=0\theta_{LOS}=0^\circ means observing in the direction of the outflow. We notice that the constraints from polarization are complementary to those from the spectral line profile. This study shows the potential of adding measurements of the Lyα\alpha degree of polarization to constrain the geometry of the gas surrounding typical star-forming galaxies and paves the way to spatially resolved studies that will allow us to disentangle between different Lyα\alpha origin mechanisms.
We present spatially resolved dust-continuum ALMA observations from rest-frame \sim60 to \sim600 μ\mum (bands 3-10) of the hyperluminous hot dust-obscured galaxy (hot DOG) WISE J224607.6-052634.9 (W2246-0526), at redshift z=4.6z=4.6. W2246-0526 is interacting with at least three companion galaxies, forming a system connected by tidal streams. We model the multiwavelength ALMA observations of the dust continuum using a modified blackbody, from which we derive the dust properties (mass, emissivity index, area of the emitting region, and temperature) in the hot DOG and resolved structures across a region of nearly \sim50 kpc. The peak temperature at the location of the hot DOG, \sim110 K, is likely the consequence of heating by the central quasar. The dust temperature drops to \sim40 K at a radius of \sim8 kpc, suggesting that heating by the quasar beyond that distance is nondominant. The dust in the connecting streams between the host and companion galaxies is at temperatures between 30-40 K, typical of starburst galaxies, suggesting it is most likely heated by recent, in-situ star formation. This is the first time dust properties are spatially resolved over several tens of kpc in a galaxy system beyond Cosmic Noon --this is more than six times the scales previously probed in galaxies at those redshifts.
We present the first contemporaneous X-ray and optical polarimetric measurement of the extremely high synchrotron peaked (EHSP) blazar H 1426+428. The X-ray polarimetric observations were undertaken using the Imaging X-ray Polarimetry Explorer (\textit{IXPE}) on 2024 May 27, and 2024 July 5. The \textit{IXPE} pointings were accompanied by contemporaneous optical observations of the Observatorio de Sierra Nevada, Calar Alto Observatory and the Perkins Telescope Observatory. While we observed the X-ray degree of polarization to be >20%>20\%, the polarization in the optical band was found to be only 13%1-3\%. This trend has been observed in several HSP blazars with available optical and X-ray polarimetric data and is typically explained in terms of energy stratification downstream of a shock. However, we observed a significant difference between the optical and X-ray polarization angles, a feature that has been observed in certain HSP blazars, such as Mrk 421, but remains a relatively rare or underreported phenomenon. We discuss possible scenarios for these findings within the framework of a partially turbulent jet model.
We present the results of VLT/MUSE integral field spectroscopic observations of the Lyα\alpha\, emission nebulae associated with 11 high redshift ($z \geq 2.9)radiogalaxies(HzRGs)withDEC) radio galaxies (HzRGs) with DEC <25^{\circ}$. When considering the other nine sources with available archival MUSE data, these observations increase the coverage to half of the currently known HzRGs. For two sources we are unable to confirm the original identification, as no Lyα\alpha\, emission was detected. We produce narrow band images centered on the Lyα\alpha\, line, extract their nuclear spectra, map their ionized gas kinematics, and derive the Lyα\alpha\, surface brightness profiles (SBPs). The SBPs are generally well reproduced by an exponential law with a typical scale length of 2030\sim 20-30 ckpc. We measure emission line ratios finding most sources in agreement with an AGN origin for their gas ionization, with a single object hinting at strong star formation. Regarding the connection between the radio and ionized gas emission, we find that while the Lyα\alpha\, nebulae are preferentially aligned with the direction of the radio emission, there is no clear correlation in terms of size or gas kinematics, and only a weak trend connecting their radio and Lyα\alpha\, luminosities. The alignment is most likely the result of anisotropic nuclear emission rather than of a direct impact of the jets into the ionized gas.
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