arXiv subjects

Ignacio Magaña Hernandez

Publications and source records attributed to Ignacio Magaña Hernandez.

22 records · Page 2Linked to original sources

arXiv2021

A Joint Ranking Statistic for Multi-messenger Astronomical Searches with Gravitational Waves

Joint ranking statistics are used to distinguish real from random coincidences, ideally considering whether shared parameters are consistent with each other as well as whether the individual candidates are distinguishable from noise. We expand on previous works to include additional shared parameters, we use galaxy catalogues aspriors for sky localization and distance, and avoid some approximations previously used. We develop methods to calculate this statistic both in low-latency using HEALPix sky maps, as well as with posterior samples. We show that these changes lead to a factor of one to two orders of magnitude improvement for GW170817-GRB 170817A depending on the method used, placing this significant event further into the foreground. We also examined the more tenuous joint candidate GBM-GW150914, which was largely penalized by these methods. Finally, we performed a simplistic simulation that argues these changes could better help distinguish between real and random coincidences in searches, although more realistic simulations are needed to confirm this.

astro-ph.IM↗

arXiv2020

Current observations are insufficient to confidently associate the binary black hole merger GW190521 with AGN J124942.3+344929

Recently, Graham et al. (2020) identified ZTF19abanrhr as a candidate electromagnetic counterpart to the binary black hole merger GW190521. The authors argue that the observations are consistent with a kicked binary black hole interacting with the accretion disk of the activate galactic nucleus AGN J124942.3+344929. If a real association (rather than happenstance), this has implications for the sources of LIGO/Virgo binary mergers, future prospects for electromagnetic counterparts, and measurements of the expansion rate of the Universe. In this Letter, we provide a re-analysis of the multi-messenger coincidence significance based on the localisation overlap and find that that the odds of a common source for GW190521 andZTF19abanrhr range between 1 and 12 depending on the waveform model used; we consider this insufficient evidence to warrant confidently associating GW190521 with ZTF19abanrhr.

astro-ph.HE↗

arXiv2020

First measurement of the Hubble parameter from bright binary black hole GW190521

The Zwicky Transient Facility (ZTF) reported the event "ZTF19abanrhr" as a candidate electromagnetic (EM) counterpart at a redshift $z=0.438$ to the gravitational wave (GW) emission from the binary black hole merger GW190521. Assuming that ZTF19abanrhr is the {\it bona fide} EM counterpart to GW190521, and using the GW luminosity distance estimate from three different waveforms NRSur7dq4, SEOBNRv4PHM, and IMRPhenomPv3HM, we report a measurement of the Hubble constant $H_0= 50.4_{-19.5}^{+28.1}$ km/s/Mpc, $ 62.2_{-19.7}^{+29.5}$ km/s/Mpc, and $ 43.1_{-11.4}^{+24.6}$ km/s/Mpc (median along with $68\%$ credible interval) respectively after marginalizing over matter density $Ω_m$ (or dark energy equation of state $w_0$) assuming the flat LCDM (or wCDM) model. Combining our results with the binary neutron star event GW170817 with its redshift measurement alone, as well as with its inclination angle inferred from Very Large Baseline Interferometry (VLBI), we find $H_0= 67.6_{-4.2}^{+4.3}$ km/s/Mpc, $Ω_m= 0.47_{-0.27}^{+0.34}$, and $w_0= -1.17_{-0.57}^{+0.68}$ (median along with $68\%$ credible interval) providing the most stringent measurement on $H_0$ and the first estimation on $Ω_m$ and $w_0$ from bright standard siren. In the future, $1.3\%$ measurement of $H_0=68$ km/s/Mpc and $28\%$ measurement of $w_0=-1$ is possible from about $200$ GW190521-like sources.

astro-ph.CO↗

arXiv2020

Cosmological Inference using Gravitational Wave Standard Sirens: A Mock Data Challenge

The observation of binary neutron star merger GW170817, along with its optical counterpart, provided the first constraint on the Hubble constant $H_0$ using gravitational wave standard sirens. When no counterpart is identified, a galaxy catalog can be used to provide the necessary redshift information. However, the true host might not be contained in a catalog which is not complete out to the limit of gravitational-wave detectability. These electromagnetic and gravitational-wave selection effects must be accounted for. We describe and implement a method to estimate $H_0$ using both the counterpart and the galaxy catalog standard siren methods. We perform a series of mock data analyses using binary neutron star mergers to confirm our ability to recover an unbiased estimate of $H_0$. Our simulations used a simplified universe with no redshift uncertainties or galaxy clustering, but with different magnitude-limited catalogs and assumed host galaxy properties, to test our treatment of both selection effects. We explore how the incompleteness of catalogs affects the final measurement of $H_0$, as well as the effect of weighting each galaxy's likelihood of being a host by its luminosity. In our most realistic simulation, where the simulated catalog is about three times denser than the density of galaxies in the local universe, we find that a 4.4\% measurement precision can be reached using galaxy catalogs with 50\% completeness and $\sim 250$ binary neutron star detections with sensitivity similar to that of Advanced LIGO's second observing run.

gr-qc↗