J/AJ/166/79 Spatiotemporal technosignature candidate targets (Nilipour+, 2023) ================================================================================ Signal Synchronization Strategies and Time Domain SETI with Gaia DR3. Nilipour A., Davenport J.R.A., Croft S., Siemion A.P.V. =2023AJ....166...79N ================================================================================ ADC_Keywords: Stars, variable; Positional data; Photometry, UBVRI Keywords: Technosignatures ; Astrobiology ; Search for extraterrestrial intelligence ; Astrometry Abstract: Spatiotemporal techniques for signal coordination with actively transmitting extraterrestrial civilizations, without the need for prior communication, can constrain technosignature searches to a significantly smaller coordinate space. With the variable star catalog from Gaia Data Release 3, we explore two related signaling strategies: the SETI Ellipsoid, and that proposed by Seto, which are both based on the synchronization of transmissions with a conspicuous astrophysical event. This data set contains more than 10 million variable star candidates with light curves from the first three years of Gaia's operational phase, between 2014 and 2017. Using four different historical supernovae as source events, we find that less than 0.01% of stars in the sample have crossing times, the times at which we would expect to receive synchronized signals on Earth, within the date range of available Gaia observations. For these stars, we present a framework for technosignature analysis that searches for modulations in the variability parameters by splitting the stellar light curve at the crossing time. Description: We have presented both a spatiotemporal technosignature candidate search framework, which combines the SETI Ellipsoid and Seto methods, and a novel SETI approach that is sensitive to changes in a periodic star's variability parameters. We find a total of 868 candidates with SETI Ellipsoid or Seto crossing times falling in the time range of Gaia DR3 epoch photometry. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 271 868 Candidate targets -------------------------------------------------------------------------------- See also: I/350 : Gaia EDR3 (Gaia Collaboration, 2020) I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021) J/A+A/652/A76 : Gaia Photometric Science Alerts (Hodgkin+, 2021) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 I19 --- ID Gaia Source ID 21- 41 F21.17 deg RAdeg [0/360] Right Ascension, Gaia DR3 (ICRS at Epoch=2016.0) 43- 63 F21.17 deg DEdeg [-90/83] Declination, Gaia DR3 (ICRS at Epoch=2016.0) 65- 75 F11.6 pc Dist [13.7/5073] Distance (1) 77- 87 F11.6 pc E_Dist [13/7528] Distance Upper Uncertainty Limit (84th percentile) (1) 89- 99 F11.6 pc e_Dist [13/4325] Distance Lower Uncertainty Limit (16th percentile) (1) 101-123 F23.17 pc X [-1850/5035] Galactocentric X Coordinate 125-145 F21.16 pc Y [-456/2373] Galactocentric Y Coordinate 147-168 F22.17 pc Z [-408/682] Galactocentric Z Coordinate 170-179 F10.7 mag Gmag [6.43/20.9] Gaia G Band Magnitude 181-190 F10.7 mag BPmag [6.63/21.2] Gaia BP Band Magnitude 192-201 F10.7 mag RPmag [5.82/20.3] Gaia RP Band Magnitude 203-228 A26 --- Class Gaia Variability Classification 230-247 F18.10 d XTime [2456852/2457901] Crossing Time (BJD) 249-253 A5 --- Seto Seto Method (2) 255-259 A5 --- SN Supernova Source Event, Table 1 261-271 F11.9 yr e_XTime [0.02/1.5]? Crossing Time Error -------------------------------------------------------------------------------- Note (1): Distances and upper/lower uncertainty limits, at the 16th and 84th percentiles, are taken from Bailer-Jones+, I/352. Note (2): Seto Method False indicates that the SETI Ellipsoid method was used to get the target candidate; True indicates that the Seto method was used. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Coralie Fix [CDS], 12-Mar-2024