TY - JOUR A1 - Bulla, Mattia A1 - Coughlin, Michael W. A1 - Dhawan, Suhail A1 - Dietrich, Tim T1 - Multi-messenger constraints on the Hubble constant through combination of gravitational waves, gamma-ray bursts and kilonovae from neutron star mergers JF - Universe : open access journal N2 - The simultaneous detection of gravitational waves and light from the binary neutron star merger GW170817 led to independent measurements of distance and redshift, providing a direct estimate of the Hubble constant H-0 that does not rely on a cosmic distance ladder, nor assumes a specific cosmological model. By using gravitational waves as "standard sirens", this approach holds promise to arbitrate the existing tension between the H-0 value inferred from the cosmic microwave background and those obtained from local measurements. However, the known degeneracy in the gravitational-wave analysis between distance and inclination of the source led to a H-0 value from GW170817 that was not precise enough to resolve the existing tension. In this review, we summarize recent works exploiting the viewing-angle dependence of the electromagnetic signal, namely the associated short gamma-ray burst and kilonova, to constrain the system inclination and improve on H-0. We outline the key ingredients of the different methods, summarize the results obtained in the aftermath of GW170817 and discuss the possible systematics introduced by each of these methods. KW - gravitational waves KW - stars: neutron KW - stars: binaries KW - cosmology: cosmological parameters KW - cosmology: distance scale KW - cosmology: cosmic background radiation Y1 - 2022 U6 - https://doi.org/10.3390/universe8050289 SN - 2218-1997 VL - 8 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Petrov, Polina A1 - Singer, Leo P. A1 - Coughlin, Michael W. A1 - Kumar, Vishwesh A1 - Almualla, Mouza A1 - Anand, Shreya A1 - Bulla, Mattia A1 - Dietrich, Tim A1 - Foucart, Francois A1 - Guessoum, Nidhal T1 - Data-driven expectations for electromagnetic counterpart searches based on LIGO/Virgo public alerts JF - The astrophysical journal : an international review of spectroscopy and astronomical physics; part 1 N2 - Searches for electromagnetic counterparts of gravitational-wave signals have redoubled since the first detection in 2017 of a binary neutron star merger with a gamma-ray burst, optical/infrared kilonova, and panchromatic afterglow. Yet, one LIGO/Virgo observing run later, there has not yet been a second, secure identification of an electromagnetic counterpart. This is not surprising given that the localization uncertainties of events in LIGO and Virgo's third observing run, O3, were much larger than predicted. We explain this by showing that improvements in data analysis that now allow LIGO/Virgo to detect weaker and hence more poorly localized events have increased the overall number of detections, of which well-localized, gold-plated events make up a smaller proportion overall. We present simulations of the next two LIGO/Virgo/KAGRA observing runs, O4 and O5, that are grounded in the statistics of O3 public alerts. To illustrate the significant impact that the updated predictions can have, we study the follow-up strategy for the Zwicky Transient Facility. Realistic and timely forecasting of gravitational-wave localization accuracy is paramount given the large commitments of telescope time and the need to prioritize which events are followed up. We include a data release of our simulated localizations as a public proposal planning resource for astronomers. Y1 - 2022 U6 - https://doi.org/10.3847/1538-4357/ac366d SN - 1538-4357 VL - 924 IS - 2 PB - Institute of Physics Publ. CY - London ER -