School of Physics and Astronomy
https://qmro.qmul.ac.uk/xmlui/handle/123456789/3479
Wed, 16 Jun 2021 20:23:00 GMT2021-06-16T20:23:00ZIn situ formation of hot Jupiters with companion super-Earths
https://qmro.qmul.ac.uk/xmlui/handle/123456789/72579
In situ formation of hot Jupiters with companion super-Earths
Poon, STS; Nelson, RP; Coleman, GAL
Observations have confirmed the existence of multiple-planet systems containing a hot Jupiter and smaller planetary companions. Examples include WASP-47, Kepler-730, and TOI-1130. We examine the plausibility of forming such systems in situ using N-body simulations that include a realistic treatment of collisions, an evolving protoplanetary disc, and eccentricity/inclination damping of planetary embryos. Initial conditions are constructed using two different models for the core of the giant planet: a ‘seed-model’ and an ‘equal-mass-model’. The former has a more massive protoplanet placed among multiple small embryos in a compact configuration. The latter consists only of equal-mass embryos. Simulations of the seed-model lead to the formation of systems containing a hot Jupiter and super-Earths. The evolution consistently follows four distinct phases: early giant impacts; runaway gas accretion on to the seed protoplanet; disc damping-dominated evolution of the embryos orbiting exterior to the giant; a late chaotic phase after dispersal of the gas disc. Approximately 1 per cent of the equal-mass simulations form a giant and follow the same four-phase evolution. Synthetic transit observations of the equal-mass simulations provide an occurrence rate of 0.26 per cent for systems containing a hot Jupiter and an inner super-Earth, similar to the 0.2 per cent occurrence rate from actual transit surveys, but simulated hot Jupiters are rarely detected as single transiting planets, in disagreement with observations. A subset of our simulations form two close-in giants, similar to the WASP-148 system. The scenario explored here provides a viable pathway for forming systems with unusual architectures, but does not apply to the majority of hot Jupiters.
Fri, 21 May 2021 00:00:00 GMThttps://qmro.qmul.ac.uk/xmlui/handle/123456789/725792021-05-21T00:00:00ZNGTS-19b: A high mass transiting brown dwarf in a 17-day eccentric orbit
https://qmro.qmul.ac.uk/xmlui/handle/123456789/72578
NGTS-19b: A high mass transiting brown dwarf in a 17-day eccentric orbit
Acton, JS; Goad, MR; Burleigh, MR; Casewell, SL; Breytenbach, H; Nielsen, LD; Smith, G; Anderson, DR; Battley, MP; Bayliss, D; Bouchy, F; Bryant, EM; Csizmadia, S; Eigmüller, P; Gill, S; Gillen, E; Grieves, N; Günther, MN; Henderson, BA; Hodgkin, ST; Jackman, JAG; Jenkins, JS; Lendl, M; McCormac, J; Moyano, M; Nelson, RP; Sefako, RR; Smith, AMS; Stalport, M; Thomas, JK; Tilbrook, RH; Udry, S; West, RG; Wheatley, PJ; Worters, HL; Vines, JI; Alves, DR
We present the discovery of NGTS-19b, a high-mass transiting brown dwarf discovered by the Next Generation Transit Survey. We investigate the system using follow-up photometry from the South African Astronomical Observatory, as well as sector 11 Transiting Exoplanet Survey Satellite data, in combination with radial velocity measurements from the CORALIE spectrograph to precisely characterize the system. We find that NGTS-19b is a brown dwarf companion to a K-star, with a mass of 69.5+5.7−5.4 MJup and radius of 1.034+0.055−0.053RJup. The system has a reasonably long period of 17.84 d, and a high degree of eccentricity of 0.3767+0.0061−0.0061. The mass and radius of the brown dwarf imply an age of 0.46+0.26−0.15 Gyr, however, this is inconsistent with the age determined from the host star spectral energy distribution, suggesting that the brown dwarf may be inflated. This is unusual given that its large mass and relatively low levels of irradiation would make it much harder to inflate. NGTS-19b adds to the small, but growing number of brown dwarfs transiting main-sequence stars, and is a valuable addition as we begin to populate the so-called brown dwarf desert.
Sat, 22 May 2021 00:00:00 GMThttps://qmro.qmul.ac.uk/xmlui/handle/123456789/725782021-05-22T00:00:00ZExact properties of an integrated correlator in N = 4 SU(N) SYM
https://qmro.qmul.ac.uk/xmlui/handle/123456789/72566
Exact properties of an integrated correlator in N = 4 SU(N) SYM
Dorigoni, D; Green, MB; Wen, C
We present a novel expression for an integrated correlation function of four superconformal primaries in SU(N) N = 4 supersymmetric Yang-Mills (N = 4 SYM) theory. This integrated correlator, which is based on supersymmetric localisation, has been the subject of several recent developments. In this paper the correlator is re-expressed as a sum over a two dimensional lattice that is valid for all N and all values of the complex Yang-Mills coupling τ=θ/2π+4πi/g2YM. In this form it is manifestly invariant under SL(2, ℤ) Montonen-Olive duality. Furthermore, it satisfies a remarkable Laplace-difference equation that relates the SU(N) correlator to the SU(N + 1) and SU(N − 1) correlators. For any fixed value of N the correlator can be expressed as an infinite series of non-holomorphic Eisenstein series, E(s;τ,τ¯¯¯) with s ∈ ℤ, and rational coefficients that depend on the values of N and s. The perturbative expansion of the integrated correlator is an asymptotic but Borel summable series, in which the n-loop coefficient of order (gYM/π)2n is a rational multiple of ζ(2n + 1). The n = 1 and n = 2 terms agree precisely with results determined directly by integrating the expressions in one-loop and two-loop perturbative N = 4 SYM field theory. Likewise, the charge-k instanton contributions (|k| = 1, 2, . . .) have an asymptotic, but Borel summable, series of perturbative corrections. The large-N expansion of the correlator with fixed τ is a series in powers of N12−ℓ (ℓ ∈ ℤ) with coefficients that are rational sums of E(s;τ,τ¯¯¯) with s ∈ ℤ + 1/2. This gives an all orders derivation of the form of the recently conjectured expansion. We further consider the ’t Hooft topological expansion of large-N Yang-Mills theory in which λ=g2YMN is fixed. The coefficient of each order in the 1/N expansion can be expanded as a series of powers of λ that converges for |λ| < π2. For large λ this becomes an asymptotic series when expanded in powers of 1/λ−−√ with coefficients that are again rational multiples of odd zeta values, in agreement with earlier results and providing new ones. We demonstrate that the large-λ series is not Borel summable, and determine its resurgent non-perturbative completion, which is O(exp(−2λ−−√)).
Wed, 12 May 2021 00:00:00 GMThttps://qmro.qmul.ac.uk/xmlui/handle/123456789/725662021-05-12T00:00:00ZNovel Representation of an Integrated Correlator in N=4 Supersymmetric Yang-Mills Theory.
https://qmro.qmul.ac.uk/xmlui/handle/123456789/72565
Novel Representation of an Integrated Correlator in N=4 Supersymmetric Yang-Mills Theory.
Dorigoni, D; Green, MB; Wen, C
An integrated correlator of four superconformal stress-tensor primaries of N=4 supersymmetric SU(N) Yang-Mills theory (SYM), originally obtained by localization, is reexpressed as a two-dimensional lattice sum that is manifestly invariant under SL(2,Z) S duality. This expression is shown to satisfy a novel Laplace equation in the complex coupling constant τ that relates the SU(N) integrated correlator to those of the SU(N+1) and SU(N-1) theories. The lattice sum is shown to precisely reproduce known perturbative and nonperturbative properties of N=4 SYM for any finite N, as well as extending previously conjectured properties of the large-N expansion.
Fri, 23 Apr 2021 00:00:00 GMThttps://qmro.qmul.ac.uk/xmlui/handle/123456789/725652021-04-23T00:00:00Z