Prospects for a local detection of dark matter with future missions to Uranus and Neptune

We investigate the possibility of detecting the gravitational influence of dark matter (DM) on the trajectory of prospective Doppler ranging missions to Uranus and Neptune. In addition, we estimate the constraints such a mission can provide on modified and massive gravity theories via extra-precession measurements using orbiters around the ice giants. We employ Monte Carlo-Markov Chain methods to reconstruct fictitious spacecraft trajectories in a simplified solar system model with varying amounts of DM. We characterise the noise on the Doppler link by the Allan deviation $\sigma_{\rm A}$, scaled on the Cassini-era value of $\sigma^{\rm{Cass}}_{\rm A}= 3 \times 10^{-15}$. Additionally, we compare the precision of prospective extra-precession measurements of Uranus and Neptune with the expected rates from simulations, in the context of modifications to the inverse square law. We estimate that the prospective mission will be sensitive to DM densities of the order of $\rho_{\rm{DM}} \sim 9 \times 10^{-20} \, (\sigma_{\rm A}/\sigma_{\rm A}^{\rm{Cass}})$ kg/m$^3$, while the $1\sigma$ bound on the expected galactic density of $\rho_{\rm{DM}} \sim 5 \times 10^{-22}$ kg/m$^3$ decreases as $1.0 \times 10^{-20} \, (\sigma_{\rm A}/\sigma^{\rm{Cass}}_{\rm A})^{0.8}$ kg/m$^3$. An improvement of two to three orders of magnitude from the baseline Allan deviation would guarantee a local detection of DM. Only a moderate reduction in ranging noise is required to rule out Milgrom's interpolating function with solar system based observations, and improve constraints the graviton mass beyond current local- or gravitational wave-based measurements. Our analysis also highlights the potential of future ranging missions to improve measurements of the standard gravitational parameters in the solar system.Comment: Published by A&

Prospects for localising Planet 9 with a future Uranus mission

Past years have seen various publications attempting to explain the apparent clustering features of trans-Neptunian objects, the most popular explanation being an unconfirmed "Planet 9". The recently proposed Uranus Orbiter and Probe mission by NASA's Planetary Science and Astrobiology Decadal Survey could offer the opportunity to precisely determine Planet 9's sky location and mass by carefully monitoring ranging data during the interplanetary cruise. We use Monte Carlo-Markov Chain methods to reconstruct simulated spacecraft trajectories in a simplified solar system model containing Planet 9, providing an estimate of the mission's localisation capacity depending on sky location, Earth-spacecraft Doppler link noise level and data collection rate. We characterise the noise via the Allan deviation $\sigma_{\rm A}$, scaled to the Cassini-era value $\sigma_{\rm A}^{\rm \scriptscriptstyle Cass} = 3 \times 10^{-15}$, finding that daily measurements of the spacecraft position can lead to $\sim$0.2 deg$^2$ localisation of Planet 9 (assuming $M_9 = 6.3 M_{\oplus}$, $d_9 = 460$AU). As little as a 3-fold improvement in $\sigma_{\rm A}$ drastically decreases the sky localisation area size to $\sim$0.01 deg$^2$. Thus, we showcase that a future Uranus mission carries a significant potential also for non-Uranian science.Comment: Submitted to MNRAS: Letters, 5 pages, 4 figure

Prospects for Localizing Planet 9 with a Future Uranus Mission

Past years have seen various publications attempting to explain the apparent clustering features of trans-Neptunian objects, the most popular explanation being an unconfirmed ‘Planet 9’. The recently proposed Uranus Orbiter and Probe mission by NASA’s Planetary Science and Astrobiology Decadal Survey could offer the opportunity to precisely determine Planet 9’s sky location and mass by carefully monitoring ranging data during the interplanetary cruise. We use Monte Carlo Markov chain methods to reconstruct simulated spacecraft trajectories in a simplified Solar system model containing Planet 9, providing an estimate of the mission’s localization capacity depending on sky location, Earth-spacecraft Doppler link noise level and data collection rate. We characterize the noise via the Allan deviation σA, scaled to the Cassini-era value $\sigma _{\rm A}^{\rm \scriptscriptstyle Cass} = 3 \times 10^{-15}$, finding that daily measurements of the spacecraft position can lead to ∼0.2 deg2 localization of Planet 9 (assuming M9 = 6.3 M⊕, d9 = 460 au). As little as a three-fold improvement in σA drastically decreases the sky localization area size to ∼0.01 deg2. Thus, we showcase that a future Uranus mission carries a significant potential also for non-Uranian science

Zonal Winds of Uranus and Neptune: Gravitational Harmonics, Dynamic Self-gravity, Shape, and Rotation

Uranus and Neptune exhibit fast surface zonal winds that can reach up to a few hundred meters per second. Previous studies on zonal gravitational harmonics and ohmic dissipation constraints suggest that the wind speeds diminish rapidly in relatively shallow depths within the planets. Through a case-by-case comparison between the missing dynamical gravitational harmonic from structure models, and with that expected from fluid perturbations, we put constraints on zonal wind decay in Uranus and Neptune. To this end, we generate polytropic empirical structure models of Uranus and Neptune using fourth-order theory of figures that leave hydrostatic J4 as an open parameter. Allotting the missing dynamical contribution to density perturbations caused by zonal winds (and their dynamic self-gravity), we find that the maximum scale height of zonal winds are ∼2%–3% of the planetary radii for both planets. Allowing the models to have J2 solutions in the ±5 × 10−6 range around the observed value has similar implications. The effect of self-gravity on is roughly a factor of ten lower than that of zonal winds, as expected. The decay scale heights are virtually insensitive to the proposed modifications to the bulk rotation periods of Uranus and Neptune in the literature. Additionally, we find that the dynamical density perturbations due to zonal winds have a measurable impact on the shape of the planet, and could potentially be used to infer wind decay and bulk rotation period via future observations

Searching for gravitational waves via Doppler tracking by future missions to Uranus and Neptune

The past year has seen numerous publications underlining the importance of a space mission to the ice giants in the upcoming decade. Proposed mission plans involve a ∼10 yr cruise time to the ice giants. This cruise time can be utilized to search for low-frequency gravitational waves (GWs) by observing the Doppler shift caused by them in the Earth–spacecraft radio link. We calculate the sensitivity of prospective ice giant missions to GWs. Then, adopting a steady-state black hole binary population, we derive a conservative estimate for the detection rate of extreme mass ratio inspirals (EMRIs), supermassive black hole (SMBH), and stellar mass binary black hole (sBBH) mergers. We link the SMBH population to the fraction of quasars fbin resulting from Galaxy mergers that pair SMBHs to a binary. For a total of 10 40-d observations during the cruise of a single spacecraft, O(fbin)∼0.5 detections of SMBH mergers are likely, if Allan deviation of Cassini-era noise is improved by ∼102 in the 10−5 − 10−3 Hz range. For EMRIs the number of detections lies between O(0.1) and O(100)⁠. Furthermore, ice giant missions combined with the Laser Interferometer Space Antenna (LISA) would improve the localization by an order of magnitude compared to LISA by itself

Searching for gravitational waves via Doppler tracking by future missions to Uranus and Neptune

The past year has seen numerous publications underlining the importance of a space mission to the ice giants in the upcoming decade. Proposed mission plans involve a $\sim$10 year cruise time to the ice giants. This cruise time can be utilized to search for low-frequency gravitational waves (GWs) by observing the Doppler shift caused by them in the Earth-spacecraft radio link. We calculate the sensitivity of prospective ice giant missions to GWs. Then, adopting a steady-state black hole binary population, we derive a conservative estimate for the detection rate of extreme mass ratio inspirals (EMRIs), supermassive- (SMBH) and stellar mass binary black hole (sBBH) mergers. We link the SMBH population to the fraction of quasars f_\rm{bin} resulting from galaxy mergers that pair SMBHs to a binary. For a total of ten 40-day observations during the cruise of a single spacecraft, \mathcal{O}(f_\rm{bin})\sim0.5 detections of SMBH mergers are likely, if Allan deviation of Cassini-era noise is improved by $\sim 10^2$ in the $10^{-5}-10^{-3}$ Hz range. For EMRIs the number of detections lies between $\mathcal{O}(0.1) - \mathcal{O}(100)$. Furthermore, ice giant missions combined with the Laser Interferometer Space Antenna (LISA) would improve the localisation by an order of magnitude compared to LISA by itself.Comment: Accepted for publication in MNRAS: Letter

Impaired exercise capacity in electrostatic polyester powder paint workers

Purpose: Limited number of studies investigated the effects of Electrostatic powder paints (EPP) on human health. We investigated the effects of EPP exposure on lung function, exercise capacity, and quality of life, and the factors determining exercise capacity in EPP workers. Methods: Fifty-four male EPP workers and 54 age-matched healthy male individuals (control group) were included. Lung function and respiratory muscle strength were measured. The lower limit of normal (LLN) cut-points for FEV1 and FEV1/FVC were calculated. An EPT was used to evaluate bronchial hyperactivity. The handgrip and quadriceps muscle strength were evaluated using a hand-held dynamometer. An ISWT was used to determine exercise capacity. The physical activity level was questioned using the IPAQ. The SGRQ and NHP were used to assessing respiratory specific and general quality of life, respectively. Results: Duration of work, FEV1, MIP, handgrip strength, and ISWT distance were significantly lower, and the change in FEV1 after EPT and %HRmax were significantly higher in the EPP group compared to the control group (p < 0.05). There were no subjects with a < LLN for FEV1 and FEV1/FVC in both groups. In the EPP group, ISWT distance was significantly related to age, height, duration of work, FEV1, change in FEV1 after EPT, MIP, MEP, handgrip strength, IPAQ, SGRQ, and NHP total scores (p < 0.05). The change in FEV1 after EPT, MIP, and duration of work explained % 62 of the variance in the ISWT distance (p < 0.001). Conclusions: Changes in lung function based on LLN for the FEV1 and FEV1/FVC were not clinically relevant in EPP workers. Exercise capacity is impaired in EPP workers. Degree of exercise-induced bronchospasm, inspiratory muscle strength, and duration of work are the determinants of exercise capacity in EPP workers.No sponso

Bridging the micro-Hz gravitational wave gap via Doppler tracking with the Uranus Orbiter and Probe Mission: Massive black hole binaries, early universe signals and ultra-light dark matter

With the recent announcement by NASA's Planetary Science and Astrobiology Decadal Survey 2023-2032, a priority flagship mission to the planet Uranus is anticipated. Here, we explore the prospects of using the mission's radio Doppler tracking equipment to detect gravitational waves (GWs) and other analogous signals related to dark matter (DM) over the duration of its interplanetary cruise. By employing a methodology to stack tracking data in combination with Monte-Carlo Markov-Chain parameter recovery tests, we show that the mission will be sensitive to GWs over the wide frequency range of $3\times 10^{-9}$ Hz to $10^{-1}$ Hz, provided that tracking data is taken consistently over a large fraction of the cruise duration. Thus, the mission has the potential to fill the gap between pulsar timing and space-based-interferometry GW observatories. Within this assumption, we forecast the detection of $\mathcal{\mathcal{O}}(1 - 100)$ individual massive black hole binaries using two independent population models. Additionally, we determine the mission's sensitivity to both astrophysical and primordial stochastic gravitational wave backgrounds, as well as its capacity to test, or even confirm via detection, ultralight DM models. In all these cases, the tracking of the spacecraft over its interplanetary cruise would enable coverage of unexplored regions of parameter space, where signals from new phenomena in our Universe may be lurking.Comment: Submitted to Pr.D. Comments welcome

Linking Uranus’ temperature profile to wind-induced magnetic fields

The low luminosity of Uranus is still a puzzling phenomenon and has key implications for the thermal and compositional gradients within the planet. Recent studies have shown that planetary volatiles become ionically conducting under conditions that are present in the ice giants. Rapidly growing electrical conductivity with increasing depth would couple zonal flows to the background magnetic field in the planets, inducing poloidal and toroidal field perturbations Bω=BωP+BωT via the ω-effect. Toroidal perturbations BωT are expected to diffuse downwards and produce poloidal fields BαP through turbulent convection via the α-effect, comparable in strength to those of the ω-effect, BωP⁠. To estimate the strength of poloidal field perturbations for various Uranus models in the literature, we generate wind decay profiles based on Ohmic dissipation constraints assuming an ionically conducting H2–He–H2O interior. Because of the higher metallicities in outer regions of hot Uranus models, zonal winds need to decay to ∼0.1 per cent of their surface values in the outer 1 per cent of Uranus to admit decay solutions in the Ohmic framework. Our estimates suggest that colder Uranus models could potentially have poloidal field perturbations that reach up to O(0.1) of the background magnetic field in the most extreme case. The possible existence of poloidal field perturbations spatially correlated with Uranus’ zonal flows could be used to constrain Uranus’ interior structure, and presents a further case for the in situ exploration of Uranus