J/A+A/704/A234ivo://CDS.VizieR/J/A+A/704/A234CDSPearson W.J.Wang L.Rodriguez-Gomez V.Margalef-Bentabol B.,Suelves L.E.2026-03-02T06:25:50Z2025-12-12T09:49:52ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frinteracting-galaxiesvisible-astronomyGalaxy mergers can change the rate at which stars are formed. We can trace when these changes occur in simulations of galaxy mergers. However, for observed galaxies we do not know how the star-formation rate (SFR) evolves along the merger sequence as it is difficult to probe the time before or after coalescence. We aim to derive how SFR changes in observed mergers throughout the merger sequence, from a statistical perspective. Merger times were estimated for observed galaxy mergers in the Kilo Degree Survey (KiDS) using a convolutional neural network (CNN). The CNN was trained on mock KiDS images created using IllustrisTNG data. The SFRs were derived from spectral energy density fitting to KiDS and VIKINGs data. To determine the change in SFR for the merging galaxies, each merging galaxy was matched and compared to ten comparable non-merging galaxies; matching redshift, stellar mass, and local density. Mergers see an increase in SFR for galaxies from 300Myr before the merger until coalescence, continuing until at least 200Myr after the merger event. After this, there is a possibility that SFR activity in the mergers begins to decrease, but we need more data to better constrain our merger times and SFRs to confirm this. We find that more galaxies with larger stellar mass (M*) have greater SFR enhancement as they merge compared to lower M* galaxies. There is no clear trend of changing SFR enhancement as local density changes, but the least dense environments have the least SFR enhancement. The increasing SFR enhancement is likely due to closer proximity of galaxies and the presence of more close passes as the time before merger approaches 0Myr, with SFR slowing 200Myr after the merger event.2025A&A...704A.234Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/704/A234CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/347 : KiDS-ESO-DR3 multi-band source catalog (de Jong+, 2017)II/383 : ESO KiDS-DR5 multi-band source catalog (Wright+ 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/704/A234https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/704/A234http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/704/A234https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/704/A234https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/704/A234http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/704/A234GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/704/A234/table2 (Predicted merger times for KiDS merging galaxies)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/704/A234/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/704/A234/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/704/A234/table2?GETtext/xml+votable180.050000true158.45427082.74909440.0055555555555555564/1029 1032 1034 1621-1622 1625-1626 1642 1685-1686 1689-1690 1961-1962 2232-2233 2936 5/1024-1025 2048 4103 4107-4109 4113-4115 4120 4122 4124 4133 4224 5459-5461 5463 5469 6397-6399 6461 6477 6479 6481 6483 6492-6494 6498 6508-6509 6512-6514 6549-6551 6553-6557 6561-6562 6565-6567 6572-6574 6577-6578 6592-6594 6717 6733-6735 6737-6739 6748-6750 6755 6764 6768-6770 6819 6825-6828 6830 6912-6914 7823 7843 7852 7856 8828 8830-8831 8893-8894 8916 8918 8921-8922 8936 8939-8940 8967 8973 8976-8978 8984-8985 8987-8988 8994 8998 9001 9003 11262-11263 11639 11643 11645-11646 11719 11723-11724 11726-11727 11730-11734 11737-11740 11748-11750 11756 6/4105-4106 4108 4112 4128 8196 8198 8200-8202 8204 8224 16407 16409-16411 16421-16423 16427 16440-16442 16447 16449 16451 16484-16485 16487 16492-16494 16500 16504 16529-16531 16536 16538 16541-16543 16560-16561 16563-16565 16568 16576-16577 16579 16640-16642 16644 16646 16900 16902 16906 21831 21848-21849 21851 21861 21872 21874-21875 21881 21884 25567 25583 25587 25823 25839 25843 25849-25850 25852 25855 25887 25907 25913 25915 25921 25923 25929-25931 25989 25991 25996 25998-25999 26040-26042 26060 26064 26080 26173 26175 26189-26191 26193-26195 26211 26233-26235 26255 26257-26259 26300 26304 26306-26307 26316 26320 26336 26384 26400 26867 26876-26877 26879 26911 26931 26947 27004 27014-27016 27018-27019 27060-27061 27064 27066 27084 27104 27275 27296-27297 27299 27318 27324 27392-27393 27395 27397-27399 27401 27404 27408 27660 27664 31289-31291 31338 31365 31367 31371 31412 31414 31416-31418 31430 31432 34534 34537-34540 34542 35307 35309-35311 35316 35318 35547 35549-35551 35566-35567 35569 35571 35580 35582 35611 35613-35615 35623 35627 35629-35631 35633-35638 35641-35642 35644 35646-35647 35649 35652-35653 35663 35668-35669 35671 35677-35680 35682-35683 35692-35693 35696-35698 35700 35750-35753 35755 35764 35776 35778 35784 35861-35863 35865-35867 35877 35879 35885 35887 35889-35891 35896-35897 35899-35901 35903 35916-35917 35919 35922 35928-35930 35932 35934-35935 35944-35946 35956-35958 35960-35962 35970-35971 35973-35975 35981-35983 35985 35987-35988 35990-35991 35996-35998 36000-36001 36003 36010 36016 36018 36033-36038 36041 36352-36353 36357 40951 40956 40958 45035 45038-45039 45045 45047 46550-46551 46553-46555 46569 46577 46579 46588-46589 46591 46806-46807 46869-46871 46873 46875 46885-46887 46889 46891 46900-46902 46912 46914-46915 46917-46919 46940-46942 46944-46946 46964 46968 46970 47004-47005 47007 47012-47013 47015 47021 47028-47030 47033-47034 47036 47040-47042 47044-47045 47048-47050https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/704/A234?format=asciiOpticaldefaultJ/A+A/704/A234/table2Predicted merger times for KiDS merging galaxiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKiDSDR4KiDS DR4 identifier (KiDSDR4_JHHMMSS.sss+DDMMSS.ss)meta.id;meta.maincharMergerTimeNorm[0/1] Normalised merger time from CNNstat.fit.paramdoubleMergerTimeMyr[-485/492] Time after merger [Myr]Myrtime.epochint_RAPositions from Name (right ascension part)degpos.eq.ra;meta.main_DEPositions from Name (declination part)degpos.eq.dec;meta.main