27 pages, 7 figures, 3 tables
We present a re-analysis of the shear and galaxy clustering data from first-year Dark Energy Survey data (DES Y1), making use of a Hybrid Effective Field Theory (HEFT) approach to model the galaxy-matter relation on weakly non-linear scales, initially proposed in Modi et al. (2020). This allows us to explore the enhancement in cosmological constraints enabled by extending the galaxy clustering scale range typically used in projected large-scale structure analysis. Our analysis is based on a recomputed harmonic-space data vector and covariance matrix, carefully accounting for all sources of mode-coupling, non-Gaussianity and shot noise, which allows us to provide robust goodness-of-fit measures. We use the AbacusSummit suite of simulations to build an emulator for the HEFT model predictions. We find that this model can explain the galaxy clustering and shear data up to wavenumbers $k_{\rm max}\sim 0.6\, {\rm Mpc}^{-1}$. We constrain $(S_8,\Omega_m) = (0.782\pm 0.018,0.279^{+0.023}_{-0.033})$ at the fiducial $k_{\rm max}\sim 0.3\, {\rm Mpc}^{-1}$, improving to $(S_8,\Omega_m) = (0.784\pm 0.016,0.270^{+0.019}_{-0.029})$ at $k_{\rm max}\sim 0.5\, {\rm Mpc}^{-1}$. This represents a $\sim10\%$ and $\sim30\%$ improvement on the constraints derived respectively on both parameters using a linear bias relation on a reduced scale range ($k_{\rm max}\lesssim0.15\,{\rm Mpc}^{-1}$), in spite of the 15 additional parameters involved in the HEFT model. Our constraints are investigative and subject to certain caveats discussed in the text.
4 pages, 3 figures, submitted to MNRAS. Python implementation available at this https URL
The homologous collapse from rest of a uniform density sphere under its self gravity is a well-known toy model for the formation dynamics of astronomical objects ranging from stars to galaxies. Equally well-known is that the evolution of the radius with time cannot be explicitly obtained because of the transcendental nature of the differential equation solution. Rather, both radius and time are written parametrically in terms of the development angle $\theta$. We here present an explicit integral solution for radius as a function of time, exploiting methods from complex analysis recently applied to the mathematically-similar 'geometric goat problem'. Our solution can be efficiently evaluated using a Fast Fourier Transform and allows for arbitrary sampling in time, with a simple Python implementation that is $\sim$$100\times$ faster than using numerical root-finding to achieve arbitrary sampling. Our explicit solution is advantageous relative to the usual approach of first generating a uniform grid in $\theta$, since this latter results in a non-uniform radial or time sampling, less useful for applications such as generation of sub-grid physics models.
29 pages, 11 figures, accepted by AJ
The updated H-band spectral line list (from \lambda 15,000 - 17,000\AA) adopted by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) for the SDSS IV Data Release 16 (DR16) is presented here. The APOGEE line list is a combination of atomic and molecular lines with data from laboratory, theoretical, and astrophysical sources. Oscillator strengths and damping constants are adjusted using high signal-to-noise, high-resolution spectra of the Sun and alpha Boo (Arcturus) as "standard stars". Updates to the DR16 line list, when compared to the previous DR14 version, are the inclusion of molecular H_2O and FeH lines, as well as a much larger (by a factor of ~4) atomic line list, which includes significantly more transitions with hyperfine splitting. More recent references and line lists for the crucial molecules CO and OH were used, as well as for C_2 and SiH. In contrast to DR14, DR16 contains measurable lines from the heavy neutron-capture elements cerium (as Ce II), neodymium (as Nd II), and ytterbium (as Yb II), as well as one line from rubidium (as Rb I), that may be detectable in a small fraction of APOGEE red giants.
10 pages, 10 figures, accepted for publication in MNRAS
We estimate the solar peculiar velocities and Oort constants using a sample of 5,627 A-type stars with $d<0.6\,\rm kpc$ and $|z|<0.1\,\rm kpc$, selected from the LAMOST surveys. The radial and tangential velocities of these A-type stars are fitted by using a non-axisymmetric model. The best-fitting result yields the solar peculiar velocities $(U_\odot,V_\odot,W_\odot)=(11.69\pm0.68, 10.16\pm0.51, 7.67\pm0.10)\,\rm km\,s^{-1}$ and Oort constants $A=16.31\pm0.89\,\rm km\,s^{-1}\,kpc^{-1}$, $B=-11.99\pm0.79\,\rm km\,s^{-1}\,kpc^{-1}$, $C=-3.10\pm0.48\,\rm km\,s^{-1}\,kpc^{-1}$, $K=-1.25\pm1.04\,\rm km\,s^{-1}\,kpc^{-1}$, respectively. $|K+C|>4\,\rm km\,s^{-1}\,kpc^{-1}$ means that there is a radial velocity gradient in the extended local disk, implying the local disk is in a non-asymmetric potential. Using the derived Oort constants, we derive the local angular velocity $\Omega\,{\approx}\,A-B=28.30\pm1.19\,\rm km\,s^{-1}\,kpc^{-1}$. By using A-type star sample of different volumes, we further try to evaluate the impacts of the ridge pattern in $R$-$V_{\phi}$ plane on constraining the solar motions and Oort constants. As the volume becomes larger toward the anti-center direction, the values of $A$ and $B$ become larger (implying a steeper slope of the local rotation curve) and the value of $V_\odot$ becomes smaller probably caused by the ridge structure and its signal increasing with distance.
17 pages, 10 figures. Submitted to ApJ, comments are welcome
Gas morphology and kinematics in the Milky Way contain key information for understanding the formation and evolution of our Galaxy. We present a high resolution hydrodynamical simulation based on a realistic barred Milky Way potential constrained by recent observations. Our model can reproduce most features in the observed longitude-velocity diagram, including the Central Molecular Zone, the Near and Far 3-kpc arms, the Molecular Ring, and the spiral arm tangents. It can also explain the non-circular motions of masers obtained by the recent BeSSeL2 survey. The central gas kinematics are consistent with a mass of $6.9\times10^8\; {\rm M}_{\odot}$ in the Nuclear Stellar Disk. Our model predicts the formation of an elliptical gaseous ring surrounding the bar, which is composed of the 3-kpc arms, Norma arm, and the bar-spiral interfaces. This ring is similar to those "inner" rings in some Milky Way analogs with a boxy/peanut-shaped bulge. The kinematics of gas near the solar neighbourhood are governed by the Local arm, which is induced by the four major stellar spiral arms. The bar pattern speed constrained by our gas model is $37.5-40\; {\rm km}\;{\rm s}^{-1}\;{\rm kpc}^{-1}$, corresponding to a corotation radius of $R_{\rm CR}=6.0-6.4\;{\rm kpc}$. The rotation curve of our model rises gently within the central $\sim5\;{\rm kpc}$, which is significantly less steep than those predicted by modern zoom-in cosmological simulations such as Auriga.
13 pages, 12+2 figures, submitted to MNRAS
23 pages, 10 figures
MNRAS submitted, comments welcome!
Accepted by MNRAS
24 pages (incl. Appendix), 20 figures, 1 table
27 pages, 14 figures, 2 tables
24 pages; 18 figures; to be submitted to MNRAS; comments welcome
28 pages, accepted to ApJ
16 pages, 9 figures, 3 tables. Accepted for publication in A&A
10 pages, 3 figures, 2 tables. Accepted for publication in MNRAS
21 pages, 18 figures, accepted in A&A
11 pages, 5 figures, 3 tables, accepted for publication in MNRAS
5 pages, 4 figures. Submitted to MNRAS Letters
9 pages, 5 figures, ASP2020 Conference Proceedings, December 2020
19 pages, 14 figures. To be published in Astronomy & Astrophysics
Accepted to ApJ on March 13, 2021
submitted to RNAAS
34 Pages, 9 Figures, 4 Tables
7 Pages, 3 Figures, Accepted for publication on Astrophysical Journal Letters
PhD Thesis, Universit\'e C\^ote d'Azur, Observatoire de la C\^ote d'Azur, 2020, 300 pages, in English. Abstract shortened to fit within arXiv character limit
12 page, 3 figures, Accepted by ApJ
11 pages, 5 Figures
27 pages, 19 figures, accepted by AJ
15 pages, accepted for publication in A&A
14 pages, 14 figures, submitted to MNRAS
36 pages, 17 figures and 2 tables, accepted for publication in ApJs
47 pages, 13 figures, submitted to P&SS
26 pages, 14 figures, submitted to MNRAS
18 pages, 12 figures, Accepted for publication in MNRAS
19 pages, 11 figures, submitted to MNRAS on 8. Feb. 2021
18 pages, 4 figures, contribution to special issue
Aceepted for publication in MNRAS. 10 pages, 9 figures
13 pages, 4 figures, accepted for publication on AAS journals
10 pages, 10 figures; accepted for publication in MNRAS
22 pages, 28 figures, arXiv-only submission
Submitted for publication to Icarus. Comments and suggestions are welcome!
Accepted for publication in MNRAS
Accepted to MNRAS
9 pages, 5 figures, accepted for publication on ApjL
17 pages, 11 figures, 2 tables, submitted to Physical Review D
10 pages, 7 figures
Submitted for publication 13 October 2020; Minor revisions 18 March 2021
13 pages, 20 figures. Accepted for publication in A&A
PhD Thesis, University of St Andrews, 2017; 249 pages; Also available from: this https URL
43 pages, 13 figures. Latex file
5 pages, 3 figures, comments are welcomed
38+30 pages, 14 figures
12 pages, 7 figures
8 pages, 8 figures
13 pages, 3 figures, 1 table
25 pages, 12 figures, 2 tables
1 figure, 2 tables, 10 pages
11 pages, 9 figures