@article{giertych_shaban_haravu_williams_2024, title={A statistical primer on classical period-finding techniques in astronomy}, volume={87}, ISSN={["1361-6633"]}, url={https://doi.org/10.1088/1361-6633/ad4586}, DOI={10.1088/1361-6633/ad4586}, abstractNote={Abstract The aim of our paper is to investigate the properties of the classical phase-dispersion minimization (PDM), analysis of variance (AOV), string-length (SL), and Lomb–Scargle (LS) power statistics from a statistician’s perspective. We confirm that when the data are perturbations of a constant function, i.e. under the null hypothesis of no period in the data, a scaled version of the PDM statistic follows a beta distribution, the AOV statistic follows an F distribution, and the LS power follows a chi-squared distribution with two degrees of freedom. However, the SL statistic does not have a closed-form distribution. We further verify these theoretical distributions through simulations and demonstrate that the extreme values of these statistics (over a range of trial periods), often used for period estimation and determination of the false alarm probability (FAP), follow different distributions than those derived for a single period. We emphasize that multiple-testing considerations are needed to correctly derive FAP bounds. Though, in fact, multiple-testing controls are built into the FAP bound for these extreme-value statistics, e.g. the FAP bound derived specifically for the maximum LS power statistic over a range of trial periods. Additionally, we find that all of these methods are robust to heteroscedastic noise aimed to mimic the degradation or miscalibration of an instrument over time. Finally, we examine the ability of these statistics to detect a non-constant periodic function via simulating data that mimics a well-detached binary system, and we find that the AOV statistic has the most power to detect the correct period, which agrees with what has been observed in practice.}, number={7}, journal={REPORTS ON PROGRESS IN PHYSICS}, author={Giertych, Naomi and Shaban, Ahmed and Haravu, Pragya and Williams, Jonathan}, year={2024}, month={Jul} }
 @article{shaban_bordoloi_chisholm_rigby_sharma_sharon_tejos_bayliss_barrientos_lopez_et al._2023, title={Dissecting a 30 kpc galactic outflow at <i>z</i> ∼ 1.7}, volume={526}, ISSN={["1365-2966"]}, url={https://doi.org/10.1093/mnras/stad3004}, DOI={10.1093/mnras/stad3004}, abstractNote={ABSTRACT We present the spatially resolved measurements of a cool galactic outflow in the gravitationally lensed galaxy RCS0327 at z ≈ 1.703 using VLT/MUSE IFU observations. We probe the cool outflowing gas, traced by blueshifted Mg ii and Fe ii absorption lines, in 15 distinct regions of the same galaxy in its image-plane. Different physical regions, 5 – 7 kpc apart within the galaxy, drive the outflows at different velocities (Vout ∼ −161 to −240 km s−1), and mass outflow rates ($\dot{M}_{out} \sim 183$ – 527 ${\rm M}_{\odot }\, \mathrm{yr}^{-1}$). The outflow velocities from different regions of the same galaxy vary by 80 km s−1, which is comparable to the variation seen in a large sample of star-burst galaxies in the local universe. Using multiply lensed images of RCS0327, we probe the same star-forming region at different spatial scales (0.5–25 kpc2), we find that outflow velocities vary between ∼ −120 and −242 km s−1, and the mass outflow rates vary between ∼37 and 254 ${\rm M}_{\odot }\, \mathrm{yr}^{-1}$. The outflow momentum flux in this galaxy is ≥ 100% of the momentum flux provided by star formation in individual regions, and outflow energy flux is ≈ 10% of the total energy flux provided by star formation. These estimates suggest that the outflow in RCS0327 is energy driven. This work shows the importance of small scale variations of outflow properties due to the variations of local stellar properties of the host galaxy in the context of galaxy evolution.}, number={4}, journal={MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY}, author={Shaban, Ahmed and Bordoloi, Rongmon and Chisholm, John and Rigby, Jane R. and Sharma, Soniya and Sharon, Keren and Tejos, Nicolas and Bayliss, Matthew B. and Barrientos, L. Felipe and Lopez, Sebastian and et al.}, year={2023}, month={Oct}, pages={6297–6320} }
 @article{shaban_bordoloi_chisholm_sharma_sharon_rigby_gladders_bayliss_barrientos_lopez_et al._2022, title={A 30 kpc Spatially Extended Clumpy and Asymmetric Galactic Outflow at z similar to 1.7}, volume={936}, ISSN={["1538-4357"]}, url={https://doi.org/10.3847/1538-4357/ac7c65}, DOI={10.3847/1538-4357/ac7c65}, abstractNote={We image the spatial extent of a cool galactic outflow with fine structure Fe II$^*$ emission and resonant Mg II emission in a gravitationally lensed star-forming galaxy at $z = 1.70347$. The Fe II$^*$ and Mg II (continuum-subtracted) emissions span out to radial distances of $\sim$14.33 kpc and 26.5 kpc, respectively, with maximum spatial extents of $\sim$21 kpc for Fe II$^*$ emission and $\sim$30 kpc for Mg II emission. Mg II residual emission is patchy and covers a total area of $\sim$184 kpc$^2$, constraining the minimum area covered by the outflowing gas to be $\sim$13% of the total area. Mg II emission is asymmetric and shows $\sim$21% more extended emission along the declination direction. We constrain the covering fractions of the Fe II$^*$ and Mg II emission as a function of radial distance and characterize them with a power law model. The Mg II 2803 emission line shows two kinematically distinct emission components, and may correspond to two distinct shells of outflowing gas with a velocity separation of $\Delta v \sim$ 400 km/s. By using multiple images with different magnifications of the galaxy in the image plane, we trace the Fe II$^*$, Mg II emissions around three individual star-forming regions. In all cases, both the Fe II$^*$ and Mg II emissions are more spatially extended compared to the star forming regions traced by the [O II] emission. These findings provide robust constraints on the spatial extent of the outflowing gas, and combined with outflow velocity and column density measurements will give stringent constraints on mass outflow rates of the galaxy.}, number={1}, journal={ASTROPHYSICAL JOURNAL}, author={Shaban, Ahmed and Bordoloi, Rongmon and Chisholm, John and Sharma, Soniya and Sharon, Keren and Rigby, Jane R. and Gladders, Michael G. and Bayliss, Matthew B. and Barrientos, L. Felipe and Lopez, Sebastian and et al.}, year={2022}, month={Sep} }
 @article{bordoloi_john m. o'meara_sharon_rigby_cooke_shaban_matuszewski_rizzi_doppmann_martin_et al._2022, title={Resolving the H i in damped Lyman alpha systems that power star formation}, volume={5}, ISSN={["1476-4687"]}, url={https://doi.org/10.1038/s41586-022-04616-1}, DOI={10.1038/s41586-022-04616-1}, abstractNote={Reservoirs of dense atomic gas (primarily hydrogen), contain approximately 90 percent of the neutral gas at a redshift of 3, and contribute to 2-3 percent of the total baryons in the Universe. These damped Lyman-${\alpha}$ systems (so called because they absorb Lyman-${\alpha}$ photons from within and from background sources) have been studied for decades, but only through absorption lines present in the spectra of background quasars and gamma-ray bursts. Such pencil beams do not constrain the physical extent of the systems. Here, we report integral-field spectroscopy of a bright, gravitationally lensed galaxy at a redshift of 2.7 with two foreground damped Lyman-${\alpha}$ systems. These systems are $>$ 238 $kpc^2$ in extent, with column densities of neutral hydrogen varying by more than an order of magnitude on $<$ 3 kpc-scales. The mean column densities are $10^{20.46}$ - $10^{20.84} cm^{-2}$ and the total masses are $> 5.5 \times 10^{8}$ - $1.4 \times 10^{9} M_{\odot}$, showing that they contain the necessary fuel for the next generation of star formation, consistent with relatively massive, low-luminosity primeval galaxies at redshifts $>$ 2.}, journal={NATURE}, publisher={Springer Science and Business Media LLC}, author={Bordoloi, Rongmon and John M. O'Meara and Sharon, Keren and Rigby, Jane R. and Cooke, Jeff and Shaban, Ahmed and Matuszewski, Mateusz and Rizzi, Luca and Doppmann, Greg and Martin, D. Christopher and et al.}, year={2022}, month={May} }