TY - JOUR
T1 - Secondary Infall in the Seyfert's Sextet
T2 - A Plausible Way Out of the Short Crossing Time Paradox
AU - López-Cruz, Omar
AU - Ibarra-Medel, Héctor Javier
AU - Sánchez, Sebastián F.
AU - Birkinshaw, Mark
AU - Añorve, Christopher
AU - Barrera-Ballesteros, Jorge K.
AU - Falcon-Barroso, Jesús
AU - Barkhouse, Wayne A.
AU - Torres-Papaqui, Juan P.
PY - 2019/11/13
Y1 - 2019/11/13
N2 - We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly-available data to investigate the star-formation histories of galaxies in the Seyfert's Sextet (SS, HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star-formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories (sSFH), we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turn-around, initially gas-rich galaxies crossed for the first time, consuming most of their gas. Hence after the second turn-around most mergers from second crossings would be mixed or dry. The exception would be gas-rich galaxies intruding for the first time. Therefore, we suggest that SS galaxies have survived one crossing during a Hubble time. Strong Balmer absorption lines and the presence of counter-rotating disks provide independent bounds to the second and first crossing, respectively. This scenario provides a plausible way out of the short crossing time paradox.
AB - We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly-available data to investigate the star-formation histories of galaxies in the Seyfert's Sextet (SS, HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star-formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories (sSFH), we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turn-around, initially gas-rich galaxies crossed for the first time, consuming most of their gas. Hence after the second turn-around most mergers from second crossings would be mixed or dry. The exception would be gas-rich galaxies intruding for the first time. Therefore, we suggest that SS galaxies have survived one crossing during a Hubble time. Strong Balmer absorption lines and the presence of counter-rotating disks provide independent bounds to the second and first crossing, respectively. This scenario provides a plausible way out of the short crossing time paradox.
KW - Star formation
KW - Stellar evolution
KW - Disk galaxies
KW - E+A galaxies
KW - Stellar evolutionary models
KW - Galaxy dynamics
KW - Galaxies
KW - Galaxy collisions
KW - Galaxy mergers
KW - Galaxy groups
KW - Galactic and extragalactic astronomy
KW - Hickson compact group
UR - http://www.scopus.com/inward/record.url?scp=85078340487&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ab5117
DO - 10.3847/2041-8213/ab5117
M3 - Article (Academic Journal)
SN - 2041-8205
VL - 886
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L2
ER -