17 research outputs found
The Gould-Hopper Polynomials in the Novikov-Veselov equation
We use the Gould-Hopper (GH) polynomials to investigate the Novikov-Veselov
(NV) equation. The root dynamics of the -flow in the NV equation is
studied using the GH polynomials and then the Lax pair is found. In particulr,
when , one can get the Gold-fish model. The smooth rational solutions
of the NV equation are also constructed via the extended Moutard transformation
and the GH polynomials. The asymptotic behavior is discussed and then the
smooth rational solution of the Liouville equation is obtained.Comment: 22 pages, no figur
Darboux transformations for a 6-point scheme
We introduce (binary) Darboux transformation for general differential
equation of the second order in two independent variables. We present a
discrete version of the transformation for a 6-point difference scheme. The
scheme is appropriate to solving a hyperbolic type initial-boundary value
problem. We discuss several reductions and specifications of the
transformations as well as construction of other Darboux covariant schemes by
means of existing ones. In particular we introduce a 10-point scheme which can
be regarded as the discretization of self-adjoint hyperbolic equation
Uncovering the stellar structure of the dusty star-forming galaxy GN20 at z=4.055 with MIRI/JWST
Luminous infrared galaxies at high redshifts (>4) include extreme
starbursts that build their stellar mass over short periods of time (>100 Myr).
These galaxies are considered to be the progenitors of massive quiescent
galaxies at intermediate redshifts (2) but their stellar structure and
buildup is unknown. Here, we present the first spatially resolved near-infrared
imaging of GN20, one of the most luminous dusty star-forming galaxies known to
date, observed at an epoch when the Universe was only 1.5 Gyr old. The
5.6m image taken with the JWST Mid-Infrared Instrument (MIRI/JWST) shows
that GN20 is a very luminous galaxy (M=25.01), with a
stellar structure composed of a conspicuous central source and an extended
envelope. The central source is an unresolved nucleus that carries 9% of the
total flux. The nucleus is co-aligned with the peak of the cold dust emission,
and offset by 3.9 kpc from the ultraviolet stellar emission. The diffuse
stellar envelope is similar in size to the clumpy CO molecular gas
distribution. The centroid of the stellar envelope is offset by 1 kpc from the
unresolved nucleus, suggesting GN20 is involved in an interaction or merger
event supported by its location as the brightest galaxy in a proto-cluster. The
stellar size of GN20 is larger by a factor of about 3-5 than known spheroids,
disks, and irregulars at 4, while its size and low S\'ersic index are
similar to those measured in dusty, infrared luminous galaxies at 2 of
the same mass. GN20 has all the ingredients necessary for evolving into a
massive spheroidal quiescent galaxy at intermediate : it is a large,
luminous galaxy at =4.05 involved in a short and massive starburst centred
in the stellar nucleus and extended over the entire galaxy, out to radii of 4
kpc, and likely induced by the interaction or merger with a member of the
proto-cluster.Comment: 7 pages, 4 figure
Strong (Hb + [OIII]) and Ha emitters at redshift z ~ 7-8 unveiled with JWST/NIRCam and MIRI imaging in the Hubble eXtreme Deep Field (XDF)
The JWST is revolutionizing the study of high-redshift galaxies by providing
for the first time a high-sensitivity view of the early Universe at infrared
wavelengths, both with its Near Infrared Camera (NIRCam) and Mid Infrared
Instrument (MIRI). In this paper, we make use of medium and broad-band NIRCam
imaging, as well as ultra-deep MIRI 5.6 microns imaging, in the Hubble eXtreme
Deep Field (XDF) to identify prominent line emitters at z ~ 7-8. Out of a total
of 58 galaxies at z ~ 7-8, we find 18 robust candidates (~31%) for prominent
(Hb + [OIII]) emitters, based on their enhanced fluxes in the F430M and F444W
filters, with rest-frame EW(Hb + [OIII]) ~ 87 - 2100 A. Among these emitters,
16 lie on the MIRI coverage area and 12 show a clear flux excess at 5.6
microns, indicating the simultaneous presence of a prominent Ha emission line
with rest-frame EW(Ha) ~ 200 - 3000 A. This is the first time that Ha emission
can be detected in individual galaxies at z>7. The Ha line, when present,
allows us to separate the contributions of the Hb and [OIII] emission lines to
the (Hb + [OIII]) complex and derive Ha-based star formation rates (SFRs). We
find that in some cases [OIII]/Hb > 1, suggesting low metallicities, but a few
have [OIII]/Hb < 1, so the NIRCam flux excess is mainly driven by Hb. The vast
majority of prominent line emitters are very young starbursts or galaxies on
their way to/from the starburst cloud. They make for a cosmic SFR density
log10(SFRD_Ha / Msun yr^-1 Mpc^-3) ~ 2.35, which is about a third of the total
value at z ~ 7-8. Therefore, the strong Ha emitters likely had an important
role in reionization.Comment: 15 pages, 9 figures. Submitted to Ap
Darboux transformations for linear operators on two dimensional regular lattices
Darboux transformations for linear operators on regular two dimensional
lattices are reviewed. The six point scheme is considered as the master linear
problem, whose various specifications, reductions, and their sublattice
combinations lead to other linear operators together with the corresponding
Darboux transformations. The second part of the review deals with
multidimensional aspects of (basic reductions of) the four point scheme, as
well as the three point scheme.Comment: 23 pages, 3 figures, presentation improve
Nonlinear Supersymmetric Quantum Mechanics: concepts and realizations
Nonlinear SUSY approach to preparation of quantum systems with pre-planned
spectral properties is reviewed. Possible multidimensional extensions of
Nonlinear SUSY are described. The full classification of ladder-reducible and
irreducible chains of SUSY algebras in one-dimensional QM is given. Emergence
of hidden symmetries and spectrum generating algebras is elucidated in the
context of Nonlinear SUSY in one- and two-dimensional QM.Comment: 75 pages, Minor corrections, Version published in Journal of Physics