THE NATURE OF STARBURSTS. I. THE STAR FORMATION HISTORIES OF EIGHTEEN NEARBY STARBURST DWARF GALAXIES

By K. McQuinn, E. Skillman, J. Cannon, J. J. Dalcanton, A. Dolphin, Sebastian Hidalgo-Rodr'iguez, J. Holtzman, D. Stark, D. Weisz, B. Williams. 2010

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We use archival Hubble Space Telescope observations of resolved stellar populations to derive the star formation histories (SFHs) of 18 nearby starburst dwarf galaxies. In this first paper, we present the observations, color–magnitude diagrams (CMDs), and the SFHs of the 18 starburst galaxies, based on a homogeneous approach to the data reduction, differential extinction, and treatment of photometric completeness. We adopt a star formation rate (SFR) threshold normalized to the average SFR of the individual system as a metric for classifying starbursts in SFHs derived from resolved stellar populations. This choice facilitates finding not only the currently bursting galaxies but also “fossil” bursts increasing the sample size of starburst galaxies in the nearby (D < 8 Mpc) universe. Thirteen of the eighteen galaxies are experiencing ongoing bursts and five galaxies show fossil bursts. From our reconstructed SFHs, it is evident that the elevated SFRs of a burst are sustained for hundreds of Myr with variations on small timescales. A long >100 Myr temporal baseline is thus fundamental to any starburst definition or identification method. The longer lived bursts rule out rapid “self-quenching” of starbursts on global scales. The bursting galaxies’ gas consumption timescales are shorter than the Hubble time for all but one galaxy confirming the short-lived nature of starbursts based on fuel limitations. Additionally, we find that the strength of the Hα emission usually correlates with the CMD-based SFR during the last 4–10 Myr. However, in four cases, the Hα emission is significantly less than what is expected for models of starbursts; the discrepancy is due to the SFR changing on timescales of a few Myr. The inherently short timescale of the Hα emission limits identifying galaxies as starbursts based on the current characteristics which may or may not be representative of the recent SFH of a galaxy.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/d28d8ffc9fa4ffbfdf731f69e2ba695082bb2b74

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Citations in the corpus

The stellar mass-halo mass relation of isolated field dwarfs : a critical test of ΛCDM at the edge of galaxy formation (2016, background): “This is further supported by the presence of large and fast-expanding HI holes (see R16b; Table 2; and Johnson et al. 2012) and the fact that it is classified as a ‘Blue Compact Dwarf’, with a very recent starburst some ∼40 Myrs ago (McQuinn et al. 2010).”
THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. I. HUBBLE SPACE TELESCOPE/WIDE FIELD PLANETARY CAMERA 2 OBSERVATIONS (2014, background): “Figures 7 and 8 show that the LG dwarf galaxies have a 14 Weisz et al. wide variety of complex SFHs, which is consistent with previous studies of nearby dwarf galaxies (e.g., Hodge 1989; Grebel 1997; Mateo 1998; Tosi 2007; Tolstoy et al. 2009; McQuinn et al. 2010a; Weisz et al. 2011a).”
THE ACS NEARBY GALAXY SURVEY TREASURY. VIII. THE GLOBAL STAR FORMATION HISTORIES OF 60 DWARF GALAXIES IN THE LOCAL VOLUME (2011, background): “Beyond the LG, only a small subset of dwarf galaxies have explicitly measured CMD-based SFHs (e.g., Dolphin et al. 2003; Weisz et al. 2008; McQuinn et al. 2009, 2010).”
Cuspy No More: How Outflows Affect the Central Dark Matter and Baryon Distribution in Lambda CDM Galaxies (2012, result): “Bursty phases typically last 10-100 Myrs with SFR variations on shorter timescales and SF enhanced by a factor of ∼ 4-20, similar to what measured in Local Group dwarfs (McQuinn et al. 2010).”
Star formation sustained by gas accretion (2014, methodology): “Even though individual HII regions last for a few Myr (e.g., Mas-Hesse & Kunth 1999; Harris et al. 2004), the SF episodes of a galaxy as a whole do not shut off within this timescale but they last for several hundred Myr (Dohm-Palmer et al. 1998; McQuinn et al. 2010b; Hidalgo et al. 2011).”