Institut de Radioastronomie Millimétrique (IRAM)
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The Event Horizon Telescope Collaboration conducted the first multi-epoch polarimetric imaging of M87* at event-horizon scales, observing a stable black hole shadow diameter while detecting substantial year-to-year variability in the ring's azimuthal brightness and linear polarization patterns, along with initial constraints on extended jet emission.
This paper accompanies Data Release 4 of the JWST Deep Extragalactic Survey (JADES), which presents the full NIRSpec spectroscopy of the survey. We provide spectra of 5190 targets across GOODS-North and GOODS-South (including the Hubble Ultra Deep Field), observed with the low-dispersion (R \sim 30-300) prism and three medium-resolution (R \sim 1000) gratings spanning 0.8 < \lambda < 5.5 microns; 2654 were also observed with the higher-resolution (R \sim 2700) G395H grating. The tiered survey design obtained more than 20 hr exposures for \sim 700 galaxies in the Deep and Ultra Deep tiers, and shallower observations (\sim 1-3 hr per setting) of > 4400 galaxies in the Medium tiers. Targets were selected from photometric redshifts or colours, with priority given to rest-UV-selected galaxies at z > 5.7 and F444W-selected galaxies at 1.5 < z < 5.7. We describe the full target selection and present spectroscopic redshifts and success rates. In total we obtain robust redshifts for 3297 galaxies, including 396 at z > 5.7 and 2545 at 1.5 < z < 5.7. To facilitate uniform analyses, we define 'gold' sub-samples based on UV- and F444W-selection. Using the parent samples and redshift success rates, we construct rest-UV luminosity functions at 6z96 \lesssim z \lesssim 9 from the Medium- and Deep-JWST tiers. Our number densities agree well with previous determinations from both photometric and spectroscopic samples, with modest interloper fractions confirming the reliability of photometric UV-bright galaxy selections at these redshifts.
Accretion rates in radio galaxies are typically estimated from optical and total radio flux measurements, incorporating emission from the core, jets, and lobes. These estimates can be used to investigate the link between observed Active Galactic Nuclei (AGN) emission properties and the underlying accretion physics of their Super-Massive Black Holes (SMBHs). However, while optical and core radio emission trace the ongoing accretion episode, extended jet and lobe structures may result from past AGN activity. Therefore, accretion rates inferred from spatially unresolved radio observations may be systematically overestimated, a bias whose prevalence and extent have yet to be thoroughly explored. In this study, using a sample of 121 local radio-loud galaxies with spatially resolved radio components, we assess this effect by estimating their \textit{Eddington}-scaled accretion rates (λ\lambda) using both the common methodology which considers total radio fluxes and a simple but novel approach that treats core and extended emission as signatures of distinct accretion phases. Our results show that the former method systematically overestimates the λ\lambda by a factor of 3\sim 3, affecting the accretion mode classification in approximately 11%11\% of sources. This discrepancy appears to correlate with radio size, with the most extended galaxies indicating a transition in accretion disk mode. Such a bias could affect AGN classification in unresolved high-redshift radio surveys. Our results motivate re-examining accretion rate calculations from AGN radio surveys and align with the AGN unification model for radio galaxies, revealing a clearer link between accretion disk physics and optical spectral properties.
Active galactic nuclei (AGNi) are a key ingredient in galaxy evolution and possibly shape galaxy growth through the generation of powerful outflows. Little is known regarding AGN-driven ionized outflows in moderate-luminosity AGNi (logLbol[erg/s]<47) beyond cosmic noon (z>3). We present the first systematic analysis of the ionized outflow properties of a sample of X-ray-selected AGNi (logLx[erg/s]>44) from the COSMOS-Legacy field at z~3.5 and with logLbol[erg/s]=45.2-46.7, by using JWST NIRSpec/IFU spectroscopic observations as part of the GA-NIFS program. We spectrally isolated and spatially resolved the ionized outflows, through a multi-component kinematic decomposition of the rest-frame optical emission lines. JWST/NIRSpec IFU data also revealed a wealth of close-by companions, of both non-AGN and AGN nature, and ionized gas streams likely tracing tidal structures and large-scale ionized gas nebulae, extending up to the circumgalactic medium. Ionized outflows are detected in all COS-AGNi targets, which we compared with results from the literature up to z~3, opportunely (re-)computed. We normalized outflow energetics (M˙out\dot{M}_{out}, E˙out\dot{E}_{out}) to the outflow density in order to standardize the various assumptions that were made in the literature. Our choice is equal to assuming that each outflow has the same gas density. We find GA-NIFS AGNi to show outflows consistent with literature results, within the large scatter shown by the collected measurements, thus suggesting no strong evolution with redshift in terms of total mass outflow rate, energy budget, and outflow velocity for fixed bolometric luminosity. Moreover, we find no clear redshift evolution of the ratio of mass outflow rate and kinetic power over AGN bolometric luminosity beyond z>1. In general, our results indicate no significant evolution of the physics driving outflows beyond z~3.[abridged]
We present the fourth data release of JADES, the JWST Advanced Deep Extragalactic Survey, providing deep spectroscopic observations in the two GOODS fields. A companion paper presents the target selection, spectroscopic redshifts and success rates, and in this paper, we discuss the data reduction and present emission line flux measurements. The spectroscopy in this work consists of medium-depth, deep and ultradeep NIRSpec/MSA spectra of 5,190 targets, covering the spectral range 0.65.50.6\text{--}5.5~\mum and observed with both the low-dispersion prism (R=30300R=30\text{--}300) and all three medium-resolution gratings (R=5001,500R=500\text{--}1,500). We describe the data reduction, analysis and description of the data products included in this data release. In total, we measured 3,297 robust redshifts out of 5,190 targets, spanning a redshift range from z=0.5z=0.5 up to z=14.2z=14.2, including 974 at z>4z>4. This data release includes 1-d and 2-d fully reduced spectra with 3 and 5 pixel extractions, with slit-loss corrections and background subtraction optimized for point sources. Furthermore, we provide redshifts and S/N>5S/N>5 emission-line flux catalogues for the prism and grating spectra, as well as new guidelines to use these data products. Lastly, we are launching a new JADES Online Database, designed to enable quick selection and browsing of this data release. Altogether, these data provide the largest statistical sample to date to characterise the properties of galaxy populations across Cosmic time.
We present the first results of V\textit{z}-GAL, a high-redshift CO(\textit{J} = 1 - 0) large survey with the Karl G. Jansky Very Large Array, targeting 92 \textit{Herschel}-selected, infrared-luminous, dusty star-forming galaxies (DSFGs). This flux density-limited sample includes 106 DSFGs in total, along with 14 galaxies from a recent pilot study -- altogether doubling the to-date available high-redshift \coonezero observations. These sources cover redshifts 1 to 6 with available mid/high-\textit{J} CO transitions from the Northern Extended Millimeter Array \zgal survey. We detect \coonezero emission in 90/92 targets above signal-to-noise ratio of 2, while two DSFGs remain undetected. \vzgal also covers additional \cotwoone emission lines in 10 of these sources. We find gas masses of the entire \vzgal sample to be (αCO/4.0)μMH2\rm (\alpha_{CO}/{4.0}) \mu {M}_{\rm H_2} = (220)×1011 M(2-20) \times {10}^{11}~\mathrm{M_{\odot}}, calibrated using \coonezero line luminosities. We confirm that these DSFGs -- with derived gas depletion timescales of (50600)(50-600) Myr -- represent a heterogeneous population, potentially comprising both main-sequence galaxies and starbursts in the early Universe. Using \coonezero luminosities as an anchor, we robustly derive the CO brightness temperature ratios with a good statistical significance up to \textit{J} = 6. Our measurements reveal a broad range of gas excitation conditions across the \vzgal DSFGs. We also explore [CI](1-0)/CO(1-0) ratios in 23 \vzgal galaxies that have existing detections of atomic carbon ground-state emission, [CI](1-0), from the \zgal survey. Our results show similar [CI]/CO ratio values across cosmic time for starbursts and local star-forming galaxy populations, supporting the use of \cionezero as an alternative cold gas tracer.
(Abridged) We explore the chemistry of the most abundant C, O, S, and N bearing species in molecular clouds, in the context of the IRAM 30 m Large Programme Gas phase Elemental abundances in Molecular Clouds (GEMS). In this work, we aim to assess the limitations introduced in the observational works when a uniform density is assumed along the line of sight for fitting the observations, developing a very simple numerical model of a turbulent box. We perform a MHD simulation in order to reproduce the turbulent steady-state of a turbulent box with properties typical of a molecular filament before collapse. We post-process the results of the MHD simulation with a chemical code to predict molecular abundances, and then post-process this cube with a radiative transfer code to create synthetic emission maps for a series of rotational transitions observed during the GEMS project. From the chemical point of view, we find that turbulence produces variations on the predicted abundances, but they are more or less critical depending on the chosen transition and the chemical age. When compared to real observations, the results from the turbulent simulation provides a better fit than when assuming a uniform gas distribution along the line of sight. In the view of our results, we conclude that taking into account turbulence when fitting observations might significantly improve the agreement with model predictions. This is especially important for sulfur bearing species that are very sensitive to the variations of density produced by turbulence at early times (0.1 Myr). The abundance of CO is also quite sensitive to turbulence when considering the evolution beyond a few 0.1 Myr.
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Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U , and V respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties.
Aims. To constrain the physical processes that lead to the birth of high-mass stars it is mandatory to study the very first stages of their formation. We search for high-mass analogs of low-mass prestellar cores in W43-MM1. Methods. We conducted a 1.3 mm ALMA mosaic of the complete W43-MM1 cloud, which has revealed numerous cores with ~ 2000 au FWHM sizes. We investigated the nature of cores located at the tip of the main filament, where the clustering is minimum. We used the continuum emission to measure the core masses and the 13^{13}CS(5-4) line emission to estimate their turbulence level. We also investigated the prestellar or protostellar nature of these cores by searching for outflow signatures traced by CO(2-1) and SiO(5-4) line emission, and for molecular complexity typical of embedded hot cores. Results. Two high-mass cores of ~ 1300 au diameter and ~ 60 M60~M_\odot mass are observed to be turbulent but gravitationally bound. One drives outflows and is associated with a hot core. The other core, W43-MM1\#6, does not yet reveal any star formation activity and thus is an excellent high-mass prestellar core candidate.
Jaime E. Pineda and colleagues present direct observational evidence of a 10,500 au-long accretion streamer feeding the young protostellar system Per-emb-2, revealing that material infall is highly asymmetric and extends far beyond the dense core boundary. This work supports predictions of non-axisymmetric accretion flows and provides a mechanism for episodic accretion events in protostars.
Context. In the past few years, there has been a rise in the detection of streamers, asymmetric flows of material directed toward the protostellar disk with material from outside the star's natal core. It is unclear how they affect the process of mass accretion, in particular beyond the Class 0 phase. Aims. We investigate the gas kinematics around Per-emb-50, a Class I source in the crowded star-forming region NGC 1333. Our goal is to study how the mass infall proceeds from envelope to disk scales in this source. Results. We discover a streamer delivering material toward Per-emb-50 in H2_2CO and C18^{18}O emission. The streamer's emission can be well described by the analytic solutions for an infalling parcel of gas along a streamline with conserved angular momentum, both in the image plane and along the line of sight velocities. The streamer has a mean infall rate of 1.3×1061.3 \times 10^{ -6} M_{ \odot} yr1^{ -1}, 5105 -10 times higher than the current accretion rate of the protostar. SO and SO2_2 emission reveal asymmetric infall motions in the inner envelope, additional to the streamer around Per-emb-50. Furthermore, the presence of SO2_2 could mark the impact zone of the infalling material. Conclusions. The streamer delivers sufficient mass to sustain the protostellar accretion rate and might produce an accretion burst, which would explain the protostar's high luminosity with respect to other Class I sources. Our results highlight the importance of late infall for protostellar evolution: streamers might provide a significant amount of mass for stellar accretion after the Class 0 phase.
We present a new catalog of 196 galaxies of the nearby Hydra I cluster out to \sim1.75r200\rm r_{200}, consisting of broad u,g,r,i,z along with narrowband Hα{\alpha} measurements. These deep optical images were obtained with the DECam camera (CTIO) and reach down to a surface brightness limit of μ(3σ;10×10)\mu( 3\sigma;10''\times10'')=26.9 mag arcsec2\rm arcsec^2 in the g band. We also report the HI properties for 89 cluster members detected with MeerKAT. A color magnitude diagram (CMD) shows a bimodal distribution typical of a cluster population, more evolved than those found in isolation. We combine optical Hα{\alpha} and WISE infrared data to compare the star formation history at two distinct timescales. Differences in the star forming activity depicted by both populations manifest as starburst in 24 found members. Of these, 18 starburst galaxies have neutral gas measurements, and show disturbed HI disks that suggest an environmentally-triggered boost in star formation within the last 107^7 yrs. Processes such as ram pressure stripping or tidal interactions may underlie their enhanced star-forming activity and asymmetric disks. Since Hydra's dynamical history is unclear, we examine the spatial and velocity distribution of the sample. We reveal a possible link between the large scale structure feeding the Hydra I cluster and the heightened star-forming activity of the starburst galaxies. This feeding pattern matches the few substructure that has been identified in Hydra in previous works, and may explain its origin. Our results portray a picture of a cluster with an evolved nature, plus a population of new infalling galaxies that manifest the impact of their first contact with the cluster environment through star formation, color, morphology and gas content transformations.
The New IRAM KID Array (NIKA) instrument is a dual-band imaging camera operating with Kinetic Inductance Detectors (KID) cooled at 100 mK. NIKA is designed to observe the sky at wavelengths of 1.25 and 2.14 mm from the IRAM 30 m telescope at Pico Veleta with an estimated resolution of 13\,arcsec and 18 arcsec, respectively. This work presents the performance of the NIKA camera prior to its opening to the astrophysical community as an IRAM common-user facility in early 2014. NIKA is a test bench for the final NIKA2 instrument to be installed at the end of 2015. The last NIKA observation campaigns on November 2012 and June 2013 have been used to evaluate this performance and to improve the control of systematic effects. We discuss here the dynamical tuning of the readout electronics to optimize the KID working point with respect to background changes and the new technique of atmospheric absorption correction. These modifications significantly improve the overall linearity, sensitivity, and absolute calibration performance of NIKA. This is proved on observations of point-like sources for which we obtain a best sensitivity (averaged over all valid detectors) of 40 and 14 mJy.s1/2^{1/2} for optimal weather conditions for the 1.25 and 2.14 mm arrays, respectively. NIKA observations of well known extended sources (DR21 complex and the Horsehead nebula) are presented. This performance makes the NIKA camera a competitive astrophysical instrument.
We present a detailed radio study of the tidal disruption events (TDEs) AT 2020zso and AT 2021sdu. Both exhibit transient radio emission beginning shortly after optical discovery and persisting for several years. For AT 2020zso, we identify two distinct radio flares. The first arises soon after the optical peak, reaching a maximum 1\sim1 year post-discovery before fading. The second flare appears 800\sim800 days after discovery and results in the brief presence of two distinct components in the radio spectra, providing strong evidence for physically separate outflows. Both flares are consistent with non-relativistic outflows, with velocities v0.10.2cv\approx0.1-0.2c and energies E1049E\sim10^{49} erg, propagating through a Bondi-like circumnuclear medium. Our analysis supports a scenario in which the first outflow is accretion-driven, launched while the TDE disk is accreting at a relatively high Eddington fraction, whereas the second outflow is associated with a transition to an advection-dominated accretion flow. In contrast, the radio emission from AT 2021sdu is best explained by a slower (v0.03cv\approx0.03c), less energetic outflow (E1048E\sim10^{48} erg), combined with diffuse, non-variable host emission that becomes dominant 500\sim500 days after discovery. Assuming free expansion, we infer an outflow launch date preceding the optical discovery date. This suggests that the outflow may originate from either the unbound stellar debris ejected during disruption or, alternatively, from a decelerating outflow. Our findings demonstrate the diversity of outflow properties in TDEs and highlight the observational challenges of interpreting late-time radio variability in the presence of host galaxy contamination.
We present a detailed analysis of J154506, a strongly lensed submillimeter galaxy (SMG) behind the Lupus-I molecular cloud, and characterization of its physical properties. Using a combination of archival and new data (including sub-arcsecond resolution (0.75\sim0.75) ALMA observations, VLT/MUSE and FORS2 optical data, as well as spectral scans from the ACA and the LMT) we identify two high-significance (SNR>5) emission lines at 97.0 and 145.5 GHz, corresponding to CO(4-3) and CO(6-5), respectively. These detections yield a spectroscopic redshift of zspec=3.7515±0.0005z_{\rm{spec}}=3.7515\pm 0.0005. We also report the detection of the [CII] 158 μ\mum fine-structure line at 400 GHz using the Atacama Pathfinder Experiment (APEX), further confirming the redshift and providing insights into J154506's physical properties. By modeling ALMA Band 6 and 7 continuum data in the uv-plane, we derive an average magnification factor of 6.0±0.46.0 \pm 0.4 and our analysis reveals a relatively cold dust (\sim37 K) in a starburst galaxy with a high intrinsic dust mass (2.5×109 M\sim2.5\times10^{9}~\rm{M}_{\odot}) and infrared (IR) luminosity (6×1012 L\sim6\times10^{12}~\rm{L}_{\odot}). The dust SED is best reproduced by a model dominated by moderately dense molecular gas (102104cm310^2-10^4\rm{cm}^{-3}), indicating that the far-infrared emission arises primarily from diffuse regions rather than compact, high-pressure environments typical of extreme starbursts or AGN. This is supported by the close-to-unity ratio between the dust and kinetic temperatures, which argues against highly energetic heating mechanisms. The CO excitation ladder peaks close to CO(5-4) and is dominated by slightly denser molecular gas. Our results underscore the unique power of far-IR and submillimeter observations to both uncover and characterize scarce, strongly lensed, high-redshift galaxies, even when obscured by foreground molecular clouds.
Magnetic fields, which play a major role in a large number of astrophysical processes from galactic to cosmological scales, can be traced via observations of dust polarization as demonstrated by the Planck satellite results. In particular, low-resolution observations of dust polarization have demonstrated that Galactic filamentary structures, where star formation takes place, are associated to well organized magnetic fields. A better understanding of this process requires detailed observations of galactic dust polarization on scales of 0.01 to 0.1 pc. Such high-resolution polarization observations can be carried out at the IRAM 30 m telescope using the recently installed NIKA2 camera, which features two frequency bands at 260 and 150 GHz (respectively 1.15 and 2.05 mm), the 260 GHz band being polarization sensitive. NIKA2 so far in commissioning phase, has its focal plane filled with ~3300 detectors to cover a Field of View (FoV) of 6.5 arcminutes diameter. The NIKA camera, which consisted of two arrays of 132 and 224 Lumped Element Kinetic Inductance Detectors (LEKIDs) and a FWHM (Full-Width-Half-Maximum) of 12 and 18.2 arcsecond at 1.15 and 2.05 mm respectively, has been operated at the IRAM 30 m telescope from 2012 to 2015 as a test-bench for NIKA2. NIKA was equipped of a room temperature polarization system (a half wave plate (HWP) and a grid polarizer facing the NIKA cryostat window). The fast and continuous rotation of the HWP permits the quasi simultaneous reconstruction of the three Stokes parameters, I, Q and U at 150 and 260 GHz. This paper presents the first polarization measurements with KIDs and reports the polarization performance of the NIKA camera and the pertinence of the choice of the polarization setup in the perspective of NIKA2. (abridged)
Active Galactic Nuclei (AGN) are believed to play a central role in quenching star formation by removing or destroying molecular gas from host galaxies via radiation-pressure driven outflows and/or radio jets. Some studies of cold molecular gas in galaxies at Cosmic Noon (z2z\sim2) show that AGN have less cold gas (&lt;100 K) compared to mass-matched star-forming galaxies. However, cold gas could also be shock-heated to warmer phases, detectable via H2_{2} transitions in the rest-frame near- and mid-infrared spectra. The Medium Resolution Spectrograph (MRS) of the Mid-infrared Instrument (MIRI) aboard JWST has opened a unique window to observe these emission lines in galaxies at Cosmic Noon. We present the first detection of hot molecular gas in cid_346, an X-ray AGN at z2.2z\sim2.2, via the H2_{2} ro-vibrational transition at 2.12 μ\mum. We measure a hot molecular gas mass of 8.0×105\sim 8.0 \times 10^{5} M_{\odot}, which is 105106\sim 10^{5}-10^{6} times lower than the cold molecular gas mass. cid_346 is located in an environment with extended gas structures and satellite galaxies. This is supported by detection of hot and cold molecular gas out to distances &gt;10 kpc in MIRI/MRS and ALMA data, respectively and ancillary NIRCam imaging that reveals two satellite galaxies at distances of \sim0.4 arcsec (3.3 kpc) and \sim0.9 arcsec (7.4 kpc) from the AGN. Our results tentatively indicate that while the CO(3-2)-based cold gas phase dominates the molecular gas mass at Cosmic Noon, H2_{2} ro-vibrational transitions are effective in tracing hot molecular gas locally in regions that may lack CO emission.
Having a detailed knowledge of the intracluster medium (ICM) to infer the exact cluster physics such as the cluster dynamical state is crucial for cluster-based cosmological studies. This knowledge limits the accuracy and precision of mass estimation, a key parameter for such studies. In this paper, we conduct an in-depth analysis of cluster ACT-CL J0240.0+0116 using a multi-wavelength approach, with a primary focus on high angular resolution Sunyaev-Zeldovich (SZ) thermal component observations obtained under the NIKA2 Sunyaev-Zeldovich Large Programme (LPSZ). We create composite images using NIKA2, X-ray, and optical galaxy number density maps. The results reveal distinct signs of disturbance within the cluster with the distributions of gas and member galaxies that do not overlap. We also find suggestions of an inflow of matter onto the cluster from the southwestern direction. Ultimately, we classify the cluster as disturbed, using morphological indicators derived from its SZ, X-ray, and optical image. The cluster SZ signal is also contaminated by a strong central point source. We adopt different approaches to handling this contaminant and find the estimates of our pressure and hydrostatic mass profiles robust to the point source mitigation model. The cluster hydrostatic mass is estimated at $4.25^{+0.50}_{-0.45\, } \times 10^{14} \,\mathrm{M}_{\odot}$ for the case where the point source was masked. These values are consistent with the mass estimated using only X-ray data and with those from previous SZ studies of the Atacama cosmology telescope (ACT) survey, with improved precision on the mass estimate. Our findings strongly suggest that ACT-CL J0240.0+0116 is a disturbed cluster system, and the detailed observations and derived values serve as a compelling case study for the capabilities of the LPSZ in mapping the cluster ICM with high precision.
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We present the results from a full polarization study carried out with ALMA during the first VLBI campaign, which was conducted in Apr 2017 in the λ\lambda3mm and λ\lambda1.3mm bands, in concert with the Global mm-VLBI Array (GMVA) and the Event Horizon Telescope (EHT), respectively. We determine the polarization and Faraday properties of all VLBI targets, including Sgr A*, M87, and a dozen radio-loud AGN. We detect high linear polarization fractions (2-15%) and large rotation measures (RM >103.3105.5>10^{3.3}-10^{5.5} rad m2^{-2}). For Sgr A* we report a mean RM of (4.2±0.3)×105(-4.2\pm0.3) \times10^5 rad m2^{-2} at 1.3 mm, consistent with measurements over the past decade, and, for the first time, an RM of (2.1±0.1)×105(-2.1\pm0.1) \times10^5 rad m2^{-2} at 3 mm, suggesting that about half of the Faraday rotation at 1.3 mm may occur between the 3 mm photosphere and the 1.3 mm source. We also report the first unambiguous measurement of RM toward the M87 nucleus at mm wavelengths, which undergoes significant changes in magnitude and sign reversals on a one year time-scale, spanning the range from -1.2 to 0.3 ×105\times\,10^5 rad m2^{-2} at 3 mm and -4.1 to 1.5 ×105\times\,10^5 rad m2^{-2} at 1.3 mm. Given this time variability, we argue that, unlike the case of Sgr A*, the RM in M87 does not provide an accurate estimate of the mass accretion rate onto the black hole. We put forward a two-component model, comprised of a variable compact region and a static extended region, that can simultaneously explain the polarimetric properties observed by both the EHT and ALMA. These measurements provide critical constraints for the calibration, analysis, and interpretation of simultaneously obtained VLBI data with the EHT and GMVA.
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