Gergely Dálya

The long-duration GRB 240222A (Fermi/GBM detection: GCN 35769; Swift/BAT detection: GCN 35770; GECAM-B detection: GCN 35782; INTEGRAL/SPI-ACS peak detection at 2024-02-22~ 08: 51: 32 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui. adsabs. harvard. edu/abs/2023A% 26A... 677A.. 40P/abstract). The detection was confirmed at the peak time 2024-02-22 08: 51: 31 UTC. The T90 duration measured by GRBAlpha is 1.5 s and the overall significance during T90 reaches 6.3 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240222A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists …

The long-duration GRB 240128A (MAXI/GSC detection: GCN 35646; CALET/CGBM detection: GCN 35647; INTEGRAL/SPI-ACS trigger no. 10493) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-01-28 15: 13: 46 UTC. The T90 duration measured by GRBAlpha is 13 s and the overall significance during T90 reaches 8 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240128A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from~ 50 keV to~ 1000 …

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

The bright long-duration GRB 240118A (Fermi/GBM detection: GCN 35558; Fermi/LAT detection: GCN 35560; NuSTAR detection: GCN 35564; Konus/Wind detection: GCN 35567; Swift/BAT detection: GCN 35522; INTEGRAL/SPI-ACS detection: trigger no. 10477) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-01-18 01: 49: 22 UTC. The T90 duration measured by GRBAlpha is 58 s and the overall significance during T90 reaches 174 sigma. The light curve shows a multiple-peaked structure which is consistent with light curves observed by other missions. However, GRBAlpha was passing through the van Allen radiation belt during the entire burst duration and therefore the measured count rate is subject to a higher variable background which cannot be distinguished from the burst itself. The light curve obtained by …

The long-duration GRB 240329A (Fermi/GBM detection: GCN 35993) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui. adsabs. harvard. edu/abs/2023A% 26A... 677A.. 40P/abstract). The detection was confirmed at the peak time 2024-03-29 21: 43: 08.0 UTC. The T90 duration measured by GRBAlpha is 6.5 s and the overall significance during T90 reaches 16 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240329A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from~ 50 keV to~ 1000 keV. To increase the …

Standard sirens have been the central paradigm in gravitational‐wave cosmology so far. From the gravitational wave signature of compact star binaries, it is possible to measure the luminosity distance of the source directly, and if additional information on the source redshift is provided, a measurement of the cosmological expansion can be performed. This review article discusses several methodologies that have been proposed to use gravitational waves for cosmological studies. Methods that use only gravitational‐wave signals and methods that use gravitational waves in conjunction with additional observations such as electromagnetic counterparts and galaxy catalogs will be discussed. The review also discusses the most recent results on gravitational‐wave cosmology, starting from the binary neutron star merger GW170817 and its electromagnetic counterpart and finishing with the population of binary black …

The short-duration GRB 240123C (AstroSat detection: GCN 35635; INTEGRAL/SPI-ACS peak detection at 2024-01-23~ 23: 12: 37) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-01-23 23: 12: 37 UTC. The T90 duration measured by GRBAlpha is 2 s and the overall significance during T90 reaches 12 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240123C_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from~ 50 keV to~ 1000 keV. To increase …

The long-duration GRB 240226A (Fermi/GBM detection: GCN 35804) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui. adsabs. harvard. edu/abs/2023A% 26A... 677A.. 40P/abstract). The sub-threshold detection was confirmed at the peak time 2024-02-26 19: 33: 09.5 UTC. The T90 duration measured by GRBAlpha is 9.5 s and the overall significance during T90 reaches 4.7 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240226A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from~ 50 keV to~ 1000 keV. To …

We present the first test of coasting cosmological models with gravitational-wave (GW) standard sirens observed in the first three observing runs of the LIGO–Virgo–KAGRA detector network. We apply the statistical galaxy catalog method adapted to coasting cosmologies and infer constraints on the H 0 Hubble constant for the three fixed values of the curvature parameter

Multi-messenger astronomy is an emerging field of research aimed at unravelling the physics governing astrophysical transients. GW170817 stands out as the first multi-messenger observation of the coalescence of a binary system of neutron stars, detected by the LIGO and Virgo gravitational-wave interferometers, along with space- and ground-based electromagnetic telescopes. It is a striking example of how multi-messenger observations significantly enhance our understanding of the physics of compact objects, relativistic outflows, and nucleosynthesis. It shows a new way of making cosmology and has the potential to resolve the tension between different measurements of the expansion rate of the Universe. To optimise multi-messenger observational strategies, to evaluate the efficiency of the searches for counterparts, and to identify the host galaxy of the source in a large sky localisation, information about the …

The long-duration GRB 240112C (Swift/BAT detection: GCN 35522; Fermi/GBM detection: GCN 35533; INTEGRAL/SPI-ACS detection: trigger no. 10466; Konus/Wind trigger at 2024-01-12 17: 37: 21.633 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-01-12 17: 37: 25 UTC. The T90 duration measured by GRBAlpha is 5 s and the overall significance during T90 reaches 12 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240112C_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a …

The detection of GW170817 (Abbott et al. 2017b) coincident with the short gamma-ray burst GRB 170817A (Goldstein et al. 2017; Savchenko et al. 2017) was a groundbreaking discovery for the multimessenger era. Not only was it the first binary neutron star (BNS) merger detected by the gravitational-wave (GW) instruments Advanced LIGO (Aasi et al. 2015) and Advanced Virgo (Acernese et al. 2014), it was also the first, and to date only, GW detection with a confirmed electromagnetic (EM) counterpart. Since then, the search for EM emission from more of these extreme events has been at the forefront of multimessenger astronomy, particularly in the gamma-ray energy band, since GRB 170817A demonstrated that BNS mergers are a progenitor of short gamma-ray bursts (GRBs; Abbott et al. 2017a). GWs have also been observed from the mergers of other compact objects, such as binary black hole (BBH) and …

The long-duration GRB 240213A (Fermi/GBM detection: GCN 35718; Glowbug detection: GCN 35728; INTEGRAL/SPI-ACS peak detection at 2024-02-13~ 20: 11: 35) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-02-13 20: 11: 48 UTC. The T90 duration measured by GRBAlpha is 44.5 s and the overall significance during T90 reaches 28 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240213A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range …

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

The long-duration GRB 240106A (Fermi/GBM detection: GCN 35490; CALET/CGBM detection: trigger no. 1388536424; INTEGRAL/SPI-ACS peak detection at 2024-01-06~ 00: 36: 35 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-01-06 00: 36: 37 UTC. The T90 duration measured by GRBAlpha is 148 s and the overall significance during T90 reaches 16 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240106A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering …

The short-duration GRB 240125A (Glowbug detection: GCN 35630; AstroSat detection: GCN 35637; CALET/CGBM detection: GCN 35639; Konus/Wind trigger at 2024-01-25 09: 35: 03.601 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The subthreshold detection was confirmed at the peak time 2024-01-25 09: 35: 00 UTC. The T90 duration measured by GRBAlpha is 1 s and the overall significance during T90 reaches 4.4 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240125A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a …

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U (1) B− L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U (1) B− L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

The detection was confirmed at the peak time 2024-02-16 10: 57: 03 UTC. The T90 duration measured by GRBAlpha is 1.0 s and the overall significance during T90 reaches 8.8 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240216A_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from~ 50 keV to~ 1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS …

The short-duration GRB 240101C (Fermi/GBM detection: GCN 35451; INTEGRAL/SPI-ACS peak detection at 2024-01-01~ 12: 57: 24 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv: 2302.10048). The detection was confirmed at the peak time 2024-01-01 12: 57: 24 UTC. The T90 duration measured by GRBAlpha is 1 s and the overall significance during T90 reaches 4.9 sigma in the 120-400 keV band. The light curve obtained by GRBAlpha is available here: https://grbalpha. konkoly. hu/static/share/GRB240101C_GCN. pdf All GRBAlpha detections are listed at: https://monoceros. physics. muni. cz/hea/GRBAlpha/GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from …

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in April of 2019 and lasting six months, O3b starting in November of 2019 and lasting five months, and O3GK starting in April of 2020 and lasting 2 weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main dataset, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.