arXiv subjects

A. T. Deller

Publications and source records attributed to A. T. Deller.

At least 55 records · Page 3Linked to original sources

arXiv2019

Radio and X-ray monitoring of the accreting millisecond X-ray pulsar IGR J17591-2342 in outburst

IGR J17591$-$2342 is a new accreting millisecond X-ray pulsar (AMXP) that was recently discovered in outburst in 2018. Early observations revealed that the source's radio emission is brighter than that of any other known neutron star low-mass X-ray binary (NS-LMXB) at comparable X-ray luminosity, and assuming its likely $\gtrsim 6$ kpc distance. It is comparably radio bright to black hole LMXBs at similar X-ray luminosities. In this work, we present the results of our extensive radio and X-ray monitoring campaign of the 2018 outburst of IGR J17591$-$2342. In total we collected 10 quasi-simultaneous radio (VLA, ATCA) and X-ray (Swift-XRT) observations, which make IGR J17591$-$2342 one of the best-sampled NS-LMXBs. We use these to fit a power-law correlation index $β= 0.37^{+0.42}_{-0.40}$ between observed radio and X-ray luminosities ( $L_\mathrm{R}\propto L_\mathrm{X}^β$). However, our monitoring revealed a large scatter in IGR J17591$-$2342's radio luminosity (at a similar X-ray luminosity, $L_\mathrm{X} \sim 10^{36}$ erg s$^{-1}$, and spectral state), with $L_\mathrm{R} \sim 4 \times 10^{29}$ erg s$^{-1}$ during the first three reported observations, and up to a factor of 4 lower $L_\mathrm{R}$ during later radio observations. Nonetheless, the average radio luminosity of IGR J17591$-$2342 is still one of the highest among NS-LMXBs, and we discuss possible reasons for the wide range of radio luminosities observed in such systems during outburst. We found no evidence for radio pulsations from IGR J17591$-$2342 in our Green Bank Telescope observations performed shortly after the source returned to quiescence. Nonetheless, we cannot rule out that IGR J17591$-$2342 becomes a radio millisecond pulsar during quiescence.

astro-ph.HE↗

arXiv2019

Quasi-simultaneous radio and X-ray observations of Aql X-1: probing low luminosities

Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least 7 different accretion outbursts. Such observations allow us to probe the interplay between accretion inflow (X-ray) and jet outflow (radio). Thus far, these combined observations have only covered one order of magnitude in radio and X-ray luminosity range; this means that any potential radio - X-ray luminosity correlation, $L_R \propto L_X^β$, is not well constrained ($β\approx$ 0.4-0.9, based on various studies) or understood. Here we present quasi-simultaneous Very Large Array and Swift-XRT observations of Aql X-1's 2016 outburst, with which we probe one order of magnitude fainter in radio and X-ray luminosity compared to previous studies ($6 \times 10^{34} < L_X < 3 \times 10^{35}$ erg s$^{-1}$, i.e., the intermediate to low-luminosity regime between outburst peak and quiescence). The resulting radio non-detections indicate that Aql X-1's radio emission decays more rapidly at low X-ray luminosities than previously assumed - at least during the 2016 outburst. Assuming similar behaviour between outbursts, and combining all available data, this can be modelled as a steep $β=1.17^{+0.30}_{-0.21}$ power-law index or as a sharp radio cut-off at $L_X \lesssim 5 \times 10^{35}$ erg s$^{-1}$ (given our deep radio upper limits at X-ray luminosities below this value). We discuss these results in the context of other similar studies.

astro-ph.HE↗

arXiv2019

Potential Kick Velocity distribution of black hole X-ray binaries and implications for natal kicks

We use Very Long Baseline Interferometry to measure the proper motions of three black hole X-ray binaries (BHXBs). Using these results together with data from the literature and Gaia-DR2 to collate the best available constraints on proper motion, parallax, distance and systemic radial velocity of 16 BHXBs, we determined their three dimensional Galactocentric orbits. We extended this analysis to estimate the probability distribution for the potential kick velocity (PKV) a BHXB system could have received on formation. Constraining the kicks imparted to BHXBs provides insight into the birth mechanism of black holes (BHs). Kicks also have a significant effect on BH-BH merger rates, merger sites, and binary evolution, and can be responsible for spin-orbit misalignment in BH binary systems. $75\%$ of our systems have potential kicks $>70\,\rm{km~s^{-1}}$. This suggests that strong kicks and hence spin-orbit misalignment might be common among BHXBs, in agreement with the observed quasi-periodic X-ray variability in their power density spectra. We used a Bayesian hierarchical methodology to analyse the PKV distribution of the BHXB population, and suggest that a unimodal Gaussian model with a mean of $107\pm16\,\rm{km~s^{-1}}$ is a statistically favourable fit. Such relatively high PKVs would also reduce the number of BHs likely to be retained in globular clusters. We found no significant correlation between the BH mass and PKV, suggesting a lack of correlation between BH mass and the BH birth mechanism. Our Python code allows the estimation of the PKV for any system with sufficient observational constraints.

astro-ph.HE↗

arXiv2019

A single fast radio burst localized to a massive galaxy at cosmological distance

Fast Radio Bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Non-repeating FRB observations have had insufficient positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single pulse FRB 180924 to a position 4 kpc from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web.

astro-ph.HE↗

arXiv2019

Five new real-time detections of Fast Radio Bursts with UTMOST

We detail a new fast radio burst (FRB) survey with the Molonglo Radio Telescope, in which six FRBs were detected between June 2017 and December 2018. By using a real-time FRB detection system, we captured raw voltages for five of the six events, which allowed for coherent dedispersion and very high time resolution (10.24 $μ$s) studies of the bursts. Five of the FRBs show temporal broadening consistent with interstellar and/or intergalactic scattering, with scattering timescales ranging from 0.16 to 29.1 ms. One burst, FRB181017, shows remarkable temporal structure, with 3 peaks each separated by 1 ms. We searched for phase-coherence between the leading and trailing peaks and found none, ruling out lensing scenarios. Based on this survey, we calculate an all-sky rate at 843 MHz of $98^{+59}_{-39}$ events sky$^{-1}$ day$^{-1}$ to a fluence limit of 8 Jy-ms: a factor of 7 below the rates estimated from the Parkes and ASKAP telescopes at 1.4 GHz assuming the ASKAP-derived spectral index $α=-1.6$ ($F_ν\proptoν^α$). Our results suggest that FRB spectra may turn over below 1 GHz. Optical, radio and X-ray followup has been made for most of the reported bursts, with no associated transients found. No repeat bursts were found in the survey.

astro-ph.HE↗

arXiv2019

VLA Observations of Single Pulses from the Galactic Center Magnetar

We present the results of a 7-12 GHz phased-array study of the Galactic center magnetar J1745-2900 with the Karl G. Jansky Very Large Array (VLA). Using data from two 6.5 hour observations from September 2014, we find that the average profile is comprised of several distinct components at these epochs and is stable over $\sim$day timescales and $\sim$GHz frequencies. Comparison with additional phased VLA data at 8.7 GHz shows significant profile changes on longer timescales. The average profile at 7-12 GHz is dominated by the jitter of relatively narrow pulses. The pulses in each of the four main profile components seen in September 2014 are uncorrelated in phase and amplitude, though there is a small but significant correlation in the occurrence of pulses in two of the profile components. Using the brightest pulses, we measure the dispersion and scattering parameters of J1745-2900. A joint fit of 38 pulses gives a 10 GHz pulse broadening time of $τ_{\rm sc, 10} = 0.09 \pm 0.03~\rm ms$ and a dispersion measure of ${\rm DM} = 1760^{+2.4}_{-1.3}~{\rm pc~cm}^{-3}$. Both of these results are consistent with previous measurements, which suggests that the scattering and dispersion measure of J1745-2900 may be stable on timescales of several years.

astro-ph.HE↗

arXiv2019

Microarcsecond VLBI pulsar astrometry with PSR$π$ II. parallax distances for 57 pulsars

We present the results of PSR$π$, a large astrometric project targeting radio pulsars using the Very Long Baseline Array (VLBA). From our astrometric database of 60 pulsars, we have obtained parallax-based distance measurements for all but 3, with a parallax precision of typically 40 $μ$as and approaching 10 $μ$as in the best cases. Our full sample doubles the number of radio pulsars with a reliable ($\gtrsim$5$σ$) model-independent distance constraint. Importantly, many of the newly measured pulsars are well outside the solar neighbourhood, and so PSR$π$ brings a near-tenfold increase in the number of pulsars with a reliable model-independent distance at $d>2$ kpc. Using our sample along with previously published results, we show that even the most recent models of the Galactic electron density distribution model contain significant shortcomings, particularly at high Galactic latitudes. When comparing our results to pulsar timing, two of the four millisecond pulsars in our sample exhibit significant discrepancies in the estimates of proper motion obtained by at least one pulsar timing array. With additional VLBI observations to improve the absolute positional accuracy of our reference sources and an expansion of the number of millisecond pulsars, we will be able to extend the comparison of proper motion discrepancies to a larger sample of pulsar reference positions, which will provide a much more sensitive test of the applicability of the solar system ephemerides used for pulsar timing. Finally, we use our large sample to estimate the typical accuracy attainable for differential astrometry with the VLBA when observing pulsars, showing that for sufficiently bright targets observed 8 times over 18 months, a parallax uncertainty of 4 $μ$as per arcminute of separation between the pulsar and calibrator can be expected.

astro-ph.IM↗

arXiv2018

Superluminal motion of a relativistic jet in the neutron star merger GW170817

The binary neutron star merger GW170817 was accompanied by radiation across the electromagnetic spectrum and localized to the galaxy NGC 4993 at a distance of 41+/-3 Mpc. The radio and X-ray afterglows of GW170817 exhibited delayed onset, a gradual rise in the emission with time as t^0.8, a peak at about 150 days post-merger, followed by a relatively rapid decline. To date, various models have been proposed to explain the afterglow emission, including a choked-jet cocoon and a successful-jet cocoon (a.k.a. structured jet). However, the observational data have remained inconclusive as to whether GW170817 launched a successful relativistic jet. Here we show, through Very Long Baseline Interferometry, that the compact radio source associated with GW170817 exhibits superluminal motion between two epochs at 75 and 230 days post-merger. This measurement breaks the degeneracy between the models and indicates that, while the early-time radio emission was powered by a wider-angle outflow (cocoon), the late-time emission was most likely dominated by an energetic and narrowly-collimated jet, with an opening angle of <5 degrees, and observed from a viewing angle of about 20 degrees. The imaging of a collimated relativistic outflow emerging from GW170817 adds substantial weight to the growing evidence linking binary neutron star mergers and short gamma-ray bursts.

astro-ph.HE↗

arXiv2018

Nowhere to Hide: Radio-faint AGN in the GOODS-N field. I. Initial catalogue and radio properties

(Abridged) Conventional radio surveys of deep fields ordinarily have arc-second scale resolutions often insufficient to reliably separate radio emission in distant galaxies originating from star-formation and AGN-related activity. Very long baseline interferometry (VLBI) can offer a solution by identifying only the most compact radio emitting regions in galaxies at cosmological distances where the high brightness temperatures (in excess of $10^5$ K) can only be reliably attributed to AGN activity. We present the first in a series of papers exploring the faint compact radio population using a new wide-field VLBI survey of the GOODS-N field. The unparalleled sensitivity of the European VLBI Network (EVN) will probe a luminosity range rarely seen in deep wide-field VLBI observations, thus providing insights into the role of AGN to radio luminosities of the order $10^{22}~\mathrm{W\,Hz^{-1}}$ across cosmic time. The newest VLBI techniques are used to completely cover an entire 7'.5 radius area to milliarcsecond resolutions, while bright radio sources ($S > 0.1$ mJy) are targeted up to 25 arcmin from the pointing centre. Multi-source self-calibration, and a primary beam model for the EVN array are used to correct for residual phase errors and primary beam attenuation respectively. This paper presents the largest catalogue of VLBI detected sources in GOODS-N comprising of 31 compact radio sources across a redshift range of 0.11-3.44, almost three times more than previous VLBI surveys in this field. We provide a machine-readable catalogue and introduce the radio properties of the detected sources using complementary data from the e-MERLIN Galaxy Evolution survey (eMERGE).

astro-ph.GA↗

arXiv2018

A VLBI distance and transverse velocity for PSR B1913+16

Using the Very Long Baseline Array, we have made astrometric observations of the binary pulsar B1913+16 spanning an 18 month period in 2014 - 2015. From these observations we make the first determination of the annual geometric parallax of B1913+16, measuring $π= 0.24^{+0.06}_{-0.08}$ milliarcseconds (68% confidence interval). The inferred parallax probability distribution differs significantly from a Gaussian. Using our parallax measurement and prior information on the spatial and luminosity distributions of the millisecond pulsar population, we infer a distance of $d=4.1^{+2.0}_{-0.7}$ kpc, which is significantly closer than the $9.8 \pm 3.1$ kpc suggested by the pulsar's dispersion measure and analyses of the ionized interstellar medium. While the relatively low significance of the parallax detection ($\sim$3$σ$) currently precludes an improved test of general relativity using the orbital decay of PSR B1913+16, ongoing observations with improved control of systematic astrometric errors could reach the 10% distance uncertainty required for this goal. The proper motion measured by our VLBI astrometry differs substantially from that obtained by pulsar timing, a discrepancy that has also been found between the proper motion measurements made by interferometers and pulsar timing for some other pulsars and which we speculate is the result of timing noise or dispersion measure variations in the timing data set. Our parallax and proper motion measurements yield a transverse velocityof $15^{+8}_{-4}$ km s$^{-1}$ in the solar reference frame. Analysis incorporating galactic rotation and solar motion finds the space velocity of the pulsar relative to its standard of rest has a component 22$^{+7}_{-3}$ km s$^{-1}$ perpendicular to the galactic plane and components of order 100 km s$^{-1}$ parallel to the galactic plane.

astro-ph.SR↗

arXiv2018

Low-frequency pulse profile variation in PSR B2217+47: evidence for echoes from the interstellar medium

We have observed a complex and continuous change in the integrated pulse profile of PSR B2217+47, manifested as additional components trailing the main peak. These transient components are detected over 6 years at $150$ MHz using the LOw Frequency ARray (LOFAR), but they are not seen in contemporaneous Lovell observations at $1.5$ GHz. We argue that propagation effects in the ionized interstellar medium (IISM) are the most likely cause. The putative structures in the IISM causing the profile variation are roughly half-way between the pulsar and the Earth and have transverse radii $R \sim 30$ AU. We consider different models for the structures. Under the assumption of spherical symmetry, their implied average electron density is $\overline{n}_e \sim 100$ cm$^{-3}$. Since PSR B2217+47 is more than an order of magnitude brighter than the average pulsar population visible to LOFAR, similar profile variations would not have been identified in most pulsars, suggesting that subtle profile variations in low-frequency profiles might be more common than we have observed to date. Systematic studies of these variations at low frequencies can provide a new tool to investigate the proprieties of the IISM and the limits to the precision of pulsar timing.

astro-ph.HE↗

arXiv2018

A radio frequency study of the accreting millisecond X-ray pulsar, IGR J16597$-$3704, in the globular cluster NGC 6256

We present Karl G. Jansky Very Large Array radio frequency observations of the new accreting millisecond X-ray pulsar (AMXP), IGR J16597$-$3704, located in the globular cluster NGC 6256. With these data, we detect a radio counterpart to IGR J16597$-$3704, and determine an improved source position. Pairing our radio observations with quasi-simultaneous Swift/XRT X-ray observations, we place IGR J16597$-$3704 on the radio -- X-ray luminosity plane, where we find that IGR J16597$-$3704 is one of the more radio-quiet neutron star low-mass X-ray binaries known to date. We discuss the mechanisms that may govern radio luminosity (and in turn jet production and evolution) in AMXPs. Further, we use our derived radio position to search for a counterpart in archival Hubble Space Telescope and Chandra X-ray Observatory data, and estimate an upper limit on the X-ray luminosity of IGR J16597$-$3704 during quiescence.

astro-ph.HE↗

arXiv2017

Jet quenching in the neutron star low-mass X-ray binary 1RXS J180408.9$-$342058

We present quasi-simultaneous radio (VLA) and X-ray ($Swift$) observations of the neutron star low-mass X-ray binary (NS-LMXB) 1RXS J180408.9$-$342058 (J1804) during its 2015 outburst. We found that the radio jet of J1804 was bright ($232 \pm 4 μ$Jy at $10$ GHz) during the initial hard X-ray state, before being quenched by more than an order of magnitude during the soft X-ray state ($19 \pm 4 μ$Jy). The source then was undetected in radio (< $13 μ$Jy) as it faded to quiescence. In NS-LMXBs, possible jet quenching has been observed in only three sources and the J1804 jet quenching we show here is the deepest and clearest example to date. Radio observations when the source was fading towards quiescence ($L_X = 10^{34-35}$ erg s$^{-1}$) show that J1804 must follow a steep track in the radio/X-ray luminosity plane with $β> 0.7$ (where $L_R \propto L_X^β$). Few other sources have been studied in this faint regime, but a steep track is inconsistent with the suggested behaviour for the recently identified class of transitional millisecond pulsars. J1804 also shows fainter radio emission at $L_X < 10^{35}$ erg s$^{-1}$ than what is typically observed for accreting millisecond pulsars. This suggests that J1804 is likely not an accreting X-ray or transitional millisecond pulsar.

astro-ph.HE↗

arXiv2017

Disk-jet coupling in low-luminosity accreting neutron stars

In outburst, neutron star X-ray binaries produce less powerful jets than black holes at a given X-ray luminosity. This has made them more difficult to study as they fade towards quiescence. To explore whether neutron stars power jets at low accretion rates ($L_{\rm X} \lesssim 10^{36}$ erg s$^{-1}$), we investigate the radio and X-ray properties of three accreting millisecond X-ray pulsars (IGR J17511-3057, SAX J1808.4-3658 and IGR J00291+5934) during their outbursts in 2015, and of the non-pulsing neutron star Cen X-4 in quiescence (2015) and in outburst (1979). We did not detect the radio counterpart of IGR J17511-3057 in outburst or of Cen X-4 in quiescence, but did detect IGR J00291+5934 and SAX J1808.4-3658, showing that at least some neutron stars launch jets at low accretion rates. While the radio and X-ray emission in IGR J00291+5934 seem to be tightly correlated, the relationship in SAX J1808.4-3658 is more complicated. We find that SAX J1808.4-3658 produces jets during the reflaring tail, and we explore a toy model to ascertain whether the radio emission could be attributed to the onset of a strong propeller. The lack of a universal radio/X-ray correlation, with different behaviours in different neutron star systems (with various radio/X-ray correlations; some being radio faint and others not), points at distinct disk-jet interactions in individual sources, while always being fainter in the radio band than black holes at the same X-ray luminosity.

astro-ph.HE↗

arXiv2016

Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz: A kpc-scale star forming disk surrounding nuclei with shocked outflows

We analyse new observations with the International Low Frequency Array (LOFAR) telescope, and archival data from the Multi-Element Radio Linked Interferometer Network (MERLIN) and the Karl G. Jansky Very Large Array (VLA). We model the spatially resolved radio spectrum of Arp 220 from 150 MHz to 33 GHz. We present an image of Arp 220 at 150 MHz with resolution $0.65''\times0.35''$, sensitivity 0.15 mJy beam$^{-1}$, and integrated flux density $394\pm59$ mJy. More than 80% of the detected flux comes from extended ($6''\approx$2.2 kpc) steep spectrum ($α=-0.7$) emission, likely from star formation in the molecular disk surrounding the two nuclei. We find elongated features extending $0.3''$ (110 pc) and $0.9''$ (330 pc) from the eastern and western nucleus respectively, which we interpret as evidence for outflows. The extent of radio emission requires acceleration of cosmic rays far outside the nuclei. We find that a simple three component model can explain most of the observed radio spectrum of the galaxy. When accounting for absorption at 1.4 GHz, Arp 220 follows the FIR/radio correlation with $q=2.36$, and we estimate a star formation rate of 220 M$_\odot\text{yr}^{-1}$. We derive thermal fractions at 1 GHz of less than 1% for the nuclei, which indicates that a major part of the UV-photons are absorbed by dust. International LOFAR observations shows great promise to detect steep spectrum outflows and probe regions of thermal absorption. However, in LIRGs the emission detected at 150 MHz does not necessarily come from the main regions of star formation. This implies that high spatial resolution is crucial for accurate estimates of star formation rates for such galaxies at 150 MHz.

astro-ph.GA↗

arXiv2016

Disk reflection and a possible disk wind during a soft X-ray state in the neutron star low-mass X-ray binary 1RXS J180408.9-342058

1RXS J180408.9-342058 is a transient neutron star low-mass X-ray binary that exhibited a bright accretion outburst in 2015. We present Nustar, Swift, and Chandra observations obtained around the peak of this outburst. The source was in a soft X-ray spectral state and displayed an X-ray luminosity of Lx~(2-3)E37 (D/5.8 kpc)^2 erg cm-2 (0.5-10 keV). The Nustar data reveal a broad Fe-K emission line that we model as relativistically broadened reflection to constrain the accretion geometry. We found that the accretion disk is viewed at an inclination of i~27-35 degrees and extended close to the neutron star, down to Rin~5-7.5 gravitational radii (~11-17 km). This inner disk radius suggests that the neutron star magnetic field strength is B<2E8 G. We find a narrow absorption line in the Chandra/HEG data at an energy of ~7.64 keV with a significance of ~4.8 sigma. This feature could correspond to blue-shifted Fe xxvi and arise from an accretion disk wind, which would imply an outflow velocity of v~0.086c (~25800 km s-1). However, this would be extreme for an X-ray binary and it is unclear if a disk wind should be visible at the low inclination angle that we infer from our reflection analysis. Finally, we discuss how the X-ray and optical properties of 1RXS J180408.9-342058 are consistent with a relatively small (Porb<3 hr) binary orbit.

astro-ph.HE↗

arXiv2016

Microarcsecond VLBI pulsar astrometry with PSRPI I. Two binary millisecond pulsars with white dwarf companions

Model-independent distance constraints to binary millisecond pulsars (MSPs) are of great value to both the timing observations of the radio pulsars, and multiwavelength observations of their companion stars. Very Long Baseline Interferometry (VLBI) astrometry can be employed to provide these model-independent distances with very high precision via the detection of annual geometric parallax. Using the Very Long Baseline Array, we have observed two binary millisecond pulsars, PSR J1022+1001 and J2145-0750, over a two-year period and measured their distances to be 700 +14 -10 pc and 613 +16 -14 pc respectively. We use the well-calibrated distance in conjunction with revised analysis of optical photometry to tightly constrain the nature of their massive (M ~ 0.85 Msun) white dwarf companions. Finally, we show that several measurements of their parallax and proper motion of PSR J1022+1001 and PSR J2145-0750 obtained by pulsar timing array projects are incorrect, differing from the more precise VLBI values by up to 5 sigma. We investigate possible causes for the discrepancy, and find that imperfect modeling of the solar wind is a likely candidate for the timing model errors given the low ecliptic latitude of these two pulsars.

astro-ph.SR↗

arXiv2015

A multi-wavelength analysis for interferometric (sub-)mm observations of protoplanetary disks: radial constraints on the dust properties and the disk structure

Theoretical models of grain growth predict dust properties to change as a function of protoplanetary disk radius, mass, age and other physical conditions. We lay down the methodology for a multi-wavelength analysis of (sub-)mm and cm continuum interferometric observations to constrain self-consistently the disk structure and the radial variation of the dust properties. The computational architecture is massively parallel and highly modular. The analysis is based on the simultaneous fit in the uv-plane of observations at several wavelengths with a model for the disk thermal emission and for the dust opacity. The observed flux density at the different wavelengths is fitted by posing constraints on the disk structure and on the radial variation of the grain size distribution. We apply the analysis to observations of three protoplanetary disks (AS 209, FT Tau, DR Tau) for which a combination of spatially resolved observations in the range ~0.88mm to ~10mm is available (from SMA, CARMA, and VLA), finding evidence of a decreasing maximum dust grain size (a_max) with radius. We derive large a_max values up to 1 cm in the inner disk between 15 and 30 AU and smaller grains with a_max~1 mm in the outer disk (R > 80AU). In this paper we develop a multi-wavelength analysis that will allow this missing quantity to be constrained for statistically relevant samples of disks and to investigate possible correlations with disk or stellar parameters.

astro-ph.GA↗