Effect of Noise Estimation in Time-Domain Ringdown Analysis: A Case Study with GW150914Wang, Hai-Tian;Shao, Lijing
doi: 10.48550/arxiv.2311.13300pmid: N/A
Abstract:Accurate noise estimation from gravitational wave (GW) data is critical for Bayesian inference. However, recent studies on ringdown signal, such as those by Isi et al. [1], Cotesta et al. [2], and Isi and Farr [3], have encountered disagreement in noise estimation, leading to inconsistent results. The key discrepancy between these studies lies in the usage of different noise estimation methods, augmented by the usage of different sampling rates. We achieved consistent results across various sampling rates by correctly managing noise estimation, shown in the case study of the GW150914 ringdown signal. By conducting a time-domain Bayesian inference analysis on GW data, starting from the peak of the signal, we discovered that the first overtone mode is weakly supported by the amplitude distribution, with a confidence level of $1.6{\sigma}$, and is slightly disfavored by the log-Bayes factor. Overall, in our time-domain analysis we conclude there is no strong evidence for overtones in GW150914.
Constraining the top-light initial mass function in the extended ultraviolet disk of M83Rautio, R. P. V.;Watkins, A. E.;Salo, H.;Venhola, A.;Knapen, J. H.;Comerón, S.
doi: 10.48550/arxiv.2311.03237pmid: N/A
Abstract:The universality or non-universality of the initial mass function (IMF) has significant implications for determining star formation rates and star formation histories from photometric properties of stellar populations. We reexamine whether the IMF is deficient in high-mass stars (top-light) in the low-density environment of the outer disk of M83 and constrain the shape of the IMF therein. Using archival Galaxy Evolution Explorer (GALEX) far ultraviolet (FUV) and near ultraviolet (NUV) data and new deep OmegaCAM narrowband H$\alpha$ imaging, we constructed a catalog of FUV-selected objects in the outer disk of M83. We counted H$\alpha$-bright clusters and clusters that are blue in FUV$-$NUV in the catalog, measured the maximum flux ratio $F_{\mathrm{H}\alpha}/f_{\lambda \mathrm{FUV}}$ among the clusters, and measured the total flux ratio $\Sigma F_{\mathrm{H}\alpha}/\Sigma f_{\lambda \mathrm{FUV}}$ over the catalog. We then compared these measurements to predictions from stellar population synthesis models made with a standard Salpeter IMF, truncated IMFs, and steep IMFs. We also investigated the effect of varying the assumed internal extinction on our results. We are not able to reproduce our observations with models using the standard Salpeter IMF or the truncated IMFs. It is only when assuming an average internal extinction of $0.10 < A_{\mathrm{V}} < 0.15$ in the outer disk stellar clusters that models with steep IMFs ($\alpha > 3.1$) simultaneously reproduce the observed cluster counts, the maximum observed $F_{\mathrm{H}\alpha}/f_{\lambda \mathrm{FUV}}$, and the observed $\Sigma F_{\mathrm{H}\alpha}/\Sigma f_{\lambda \mathrm{FUV}}$. Our results support a non-universal IMF that is deficient in high-mass stars in low-density environments.
Probing cosmology via the clustering of critical pointsShim, Junsup;Pichon, Christophe;Pogosyan, Dmitri;Appleby, Stephen;Cadiou, Corentin;Kim, Juhan;Kraljic, Katarina;Park, Changbom
doi: 10.48550/arxiv.2311.09886pmid: N/A
Abstract:Exclusion zones in the cross-correlations between critical points (peak-void, peak-wall, filament-wall, filament-void) of the density field define quasi-standard rulers that can be used to constrain dark matter and dark energy cosmological parameters. The average size of the exclusion zone is found to scale linearly with the typical distance between extrema. The latter changes as a function of the matter content of the universe in a predictable manner, but its comoving size remains essentially constant in the linear regime of structure growth on large scales, unless the incorrect cosmology is assumed in the redshift-distance relation. This can be used to constrain the dark energy parameters when considering a survey that scans a range of redshifts. The precision of the parameter estimation is assessed using a set of cosmological simulations, and is found to be a 4$\sigma$ detection of a change in matter content of 5%, or about 3.8$\sigma$ detection of 50% shift in the dark energy parameter using a full sky survey up to redshift 0.5.
Discovery of Two Different Full Disk Evolutionary Patterns of M-type T Tauri Stars with LAMOST DR8Haerken, Hasitieer;Li, Guang-Wei;Li, Min;Duan, Fuqing;Zhao, Yongheng
doi: 10.48550/arxiv.2311.05206pmid: N/A
Abstract:The full disk, full of gas and dust, determines the upper limit of planet masses, and its lifetime is critical for planet formation, especially for giant planets. In this work, we studied the evolutionary timescales of the full disks of T Tauri stars (TTSs) and their relations to accretion. Combined with Gaia EDR3, 2MASS, and WISE data, 1077 disk-bearing TTS candidates were found in LAMOST DR8, and stellar parameters were obtained. Among them, 783 are newly classified by spectra as classical T Tauri stars (CTTSs; 169) or weak-lined T Tauri stars (WTTSs). Based on EW and FWHM of Ha, 157 TTSs in accretion were identified, with ~ 82% also having full disks. For TTSs with M<0.35 Mo, about 80% seem to already lose their full disks at ~ 0.1 Myr, which may explain their lower mass, while the remaining 20% with full disks evolve at similar rates of non-full disks within 5 Myr, possibly suffice to form giant planets. The fraction of accreting TTSs to disk-bearing TTSs is stable at ~10% and can last $\sim$ 5-10 Myr, suggesting that full disks and accretion evolve with similar rates as non-full disks. For TTSs with M>0.35Mo, almost all full disks can survive more than 0.1 Myr, most for 1 Myr and some even for 20 Myr, which implies planets are more likely to be formed in their disks than those of M<0.35 Mo, and thus M dwarfs with M>0.35Mo can have more planets. The fraction of full-disk TTSs to disk-bearing TTSs decreases with age following the relation $f\propto t^{-0.35}$, and similar relations existed in the fraction of accreting TTSs and the fraction of full-disk CTTSs, suggesting faster full disks and accretion evolution than non-full disks. For full disk stars, the ratio of accretion of lower-mass stars is systematically lower than that of higher-mass stars, confirming the dependence of accretion on stellar mass.
Revisiting $\epsilon$ Eridani with NEID: Identifying New Activity-Sensitive Lines in a Young K Dwarf StarJiang, Sarah;Roy, Arpita;Halverson, Samuel;Bender, Chad F.;Selgas, Carlos;Otor, O. Justin;Mahadevan, Suvrath;Stefánsson, Guðmundur;Terrien, Ryan C.;Schwab, Christian
doi: 10.48550/arxiv.2311.10677pmid: N/A
Abstract:Recent improvements in the sensitivity and precision of the radial velocity (RV) method for exoplanets has brought it close, but not quite to, the threshold ($\sim$10 cm/s) required to detect Earth-mass and other potentially habitable planets around Sun-like stars. Stellar activity-driven noise in RV measurements remains a significant hurdle to achieving this goal. While various efforts have been made to disentangle this noise from real planetary signals, a greater understanding of the relationship between spectra and stellar activity is crucial to informing stellar activity mitigation. We use a partially automated method to analyze spectral lines in a set of observations of the young, active star $\epsilon$ Eridani from the high-precision spectrograph NEID, correlate their features (depth, full width at half maximum, and integrated flux) with known activity indicators, and filter and curate for well-behaved lines whose shape changes are sensitive to certain types of stellar activity. We then present a list of 9 lines correlated with the S-index in all three line features, including 4 newly-identified activity-sensitive lines; as well additional lines correlated with S-index in at least one feature, and discuss the possible implications of the behavior observed in these lines. Our line lists represent a step forward in the empirical understanding of the complex relationships between stellar activity and spectra, and illustrate the importance of studying the time evolution of line morphologies with stabilized spectrographs, in the overall effort to mitigate activity in the search for small, potentially Earth-like exoplanets.
Adaptive Data Reduction Workflows for Astronomy -- The ESO Data Processing System (EDPS)Freudling, Wolfram;Zampieri, Stefano;Coccato, Lodovico;Podgorski, Stanislaw;Romaniello, Martino;Modigliani, Andrea;Pritchard, John
doi: 10.48550/arxiv.2311.03822pmid: N/A
Abstract:Astronomical data reduction is usually done with processing pipelines that consist of a series of individual processing steps that can be executed stand-alone. These processing steps are then strung together into workflows and fed with data to address a particular processing goal. In this paper, we propose a data processing system that automatically derives processing workflows for different use cases from a single specification of a cascade of processing steps. The system works by using formalized descriptions of data processing pipelines that specify the input and output of each processing step. Inputs can be existing data or the output of a previous step. Rules to select the most appropriate input data are directly attached to the description. A version of the proposed system has been implemented as the ESO Data Processing System (EDPS) in the Python language. The specification of processing cascades and data organisation rules use a restrictive set of Python classes, attributes and functions. The EDPS implementation of the proposed system was used to demonstrate that it is possible to automatically derive from a single specification of a pipeline processing cascade the workflows that the European Southern Observatory uses for quality control, archive production, and specialized science reduction. The EDPS will be used to replace all data reduction systems using different workflow specifications that are currently used at the European Southern Observatory.
Retrievals Applied To A Decision Tree Framework Can Characterize Earth-like Exoplanet AnalogsYoung, Amber V.;Crouse, Jaime;Arney, Giada;Domagal-Goldman, Shawn;Robinson, Tyler D.;Bastelberger, Sandra T.
doi: 10.48550/arxiv.2311.07530pmid: N/A
Abstract:Exoplanet characterization missions planned for the future will soon enable searches for life beyond our solar system. Critical to the search will be the development of life detection strategies that can search for biosignatures while maintaining observational efficiency. In this work, we adopted a newly developed biosignature decision tree strategy for remote characterization of Earth-like exoplanets. The decision tree offers a step-by-step roadmap for detecting exoplanet biosignatures and excluding false positives based on Earth's biosphere and its evolution over time. We followed the pathways for characterizing a modern Earth-like planet and an Archean Earth-like planet and evaluated the observational trades associated with coronagraph bandpass combinations of designs consistent with The Habitable Worlds Observatory (HWO) precursor studies. With retrieval analyses of each bandpass (or combination), we demonstrate the utility of the decision tree and evaluated the uncertainty on a suite of biosignature chemical species and habitability indicators (i.e., the gas abundances of H$_2$O, O$_2$, O$_3$, CH$_4$, and CO$_2$). Notably for modern Earth, less than an order of magnitude spread in the 1-$\sigma$ uncertainties were achieved for the abundances of H$_2$O and O$_2$, planetary surface pressure, and atmospheric temperature with three strategically placed bandpasses (two in the visible and one in the near-infrared). For the Archean, CH$_4$ and H$_2$O were detectable in the visible with a single bandpass.
A Pathway for Collisional Planetesimal Growth in the Ice-Dominant Regions of Protoplanetary DisksYunerman, Elizabeth;Powell, Diana;Murray-Clay, Ruth
doi: 10.48550/arxiv.2311.04286pmid: N/A
Abstract:We present a semi-analytic model for the growth, drift, desorption, and fragmentation of millimeter- to meter-sized particles in protoplanetary disks. Fragmentation occurs where particle collision velocities exceed critical fragmentation velocities. Using this criterion, we produce fragmentation regions in disk orbital radius-particle size phase space for particles with a range of material properties, structures, and compositions (including SiO$_2$, Mg$_2$SiO$_4$, H$_2$O, CO$_2$, and CO). For reasonable disk conditions, compact aggregate H$_2$O, CO$_2$, and CO ice particles do not reach destructive relative velocities and are thus not likely to undergo collisional fragmentation. Uncoated silicate particles are more susceptible to collisional destruction and are expected to fragment in the inner disk, consistent with previous work. We then calculate the growth, drift, and sublimation of small particles, initially located in the outer disk. We find that ice-coated particles can avoid fragmentation as they grow and drift inward under a substantial range of disk conditions as long as the particles are aggregates composed of 0.1 $\mu$m-sized monomers. Such particles may undergo runaway growth in disk regions abundant in H$_2$O or CO$_2$ ice depending on the assumed disk temperature structure. These results indicate that icy collisional growth to planetesimally-relevant sizes may happen efficiently throughout a disk's lifetime, and is particularly robust at early times when the disk's dust-to-gas ratio is comparable to that of the interstellar medium.
Detection of X-ray/UV delay in NGC 4051 using AstroSat observationsKumari, Kavita;Dewangan, G. C.;Papadakis, I. E.;Singh, K. P.
doi: 10.48550/arxiv.2311.02722pmid: N/A
Abstract:We study the connection between the variations in the far ultra-violet (FUV), near ultra-violet (NUV) and X-ray band emission from NGC 4051 using 4-days long AstroSat observations performed during 5-9 June 2016. NGC 4051 showed rapid variability in all three bands with the strongest variability amplitude in the X-ray band ($F_{var} \sim 37\%$) and much weaker variability in the UV bands ($F_{var} \sim 3 - 5\%$). Cross-correlation analysis performed using Interpolated cross-correlation Functions (ICCF) and Discrete cross-correlation Functions (DCF) revealed a robust correlation ($\sim 0.75$) between the UV and X-ray light curves. The variations in the X-ray band are found to lead those in the FUV and NUV bands by $\sim 7.4{\rm~ks}$ and $\sim 24.2{\rm~ks}$, respectively. The UV lags favour the thermal disc reprocessing model. The FUV and NUV bands are strongly correlated ($\sim 0.9$) and the variations in the FUV band lead those in the NUV band by $\sim 13{\rm~ks}$. Comparison of the UV lags found using the AstroSat observations with those reported earlier and the theoretical model for thermal reverberation time-lag suggests a possible change in either the geometry of the accretion disc/corona or the height of the corona.