New SIS receivers for the IRAM Plateau de Bure interferometer

Chenu, J.-Y.; Carter, M.; Maier, D.; Bortolotti, Yves; Butin, G.; Serres, Patrice; Boucher, Cynthia; Mattiocco, F.; Lazareff, B.

doi:10.1109/icimw.2007.4516447

Cited by 3 publications

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“…Whether or not such a bimodality represents the physical reality has been questioned (e.g., Narayanan et al 2012) on the grounds of discrete "concordance" values being assumed for the CO-to-H 2 conversion factor α CO and, second, due to the expectation that SF laws at a basic level should be expressed in terms of volumetric quantities rather than observationally more easily accessible surface densities of SFR and gas (e.g., Krumholz et al 2012). The lack of known sources with SFEs between those measured for normal disk galaxies and strong SBs could also be a selection effect: initial CO follow-up observations of high-redshift galaxies targeted only highly luminous sources experiencing "bursty" SF (submillimeter galaxies and QSOs; e.g., Omont et al 1996, Frayer et al 1998, Walter et al 2003, Greve et al 2005, Maiolino et al 2007, Tacconi et al 2008 and following improvements in the sensitivity of millimeter receivers (Chenu et al 2007, Perley et al 2011, dedicated studies of typical MS galaxies were undertaken (e.g., Daddi et al 2008, 2010a, Geach et al 2011, Tacconi et al 2013, Bauermeister et al 2013a).…”

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confidence: 99%

Regularity Underlying Complexity: A Redshift-Independent Description of the Continuous Variation of Galaxy-Scale Molecular Gas Properties in the Mass-Star Formation Rate Plane

Sargent

Daddi

Béthermin

et al. 2014

ApJ

332

104

645

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Star-forming galaxies (SFGs) display a continuous specific star formation rate (sSFR) distribution which can be approximated by two log-normal functions: one encompassing the galaxy main sequence, the other a rarer, starbursting population. Starburst sSFRs can be regarded as outcome of a physical process (plausibly merging) taking the mathematical form of a log-normal boosting kernel that enhances star formation activity. We explore the utility of splitting the star-forming population into main-sequence and starburst galaxies -an approach we term "2-Star Formation Mode" (2-SFM) framework -for understanding their molecular gas properties. Star formation efficiency (SFE) and gas fraction variations among SFGs take a simple redshift-independent form, once these quantities are normalized to the corresponding values for average main-sequence galaxies. SFE enhancements during starburst episodes scale supra-linearly with the SFR increase, as expected for mergers. Consequently, galaxies separate more clearly into loci for starbursts and normal galaxies in the Schmidt-Kennicutt plane than in (s)SFR versus M ⋆ space. Starbursts with large deviations (>10-fold) from the main sequence, e.g. local ULIRGs, are not average starbursts, but are much rarer events whose progenitors had larger gas fractions than typical main-sequence galaxies. Statistically, gas fractions in starbursts are reduced two-to threefold compared to their direct main-sequence progenitors, as expected for short-lived SFR boosts where internal gas reservoirs are depleted more quickly than gas is re-accreted from the cosmic web. We predict variations of the conversion factor α CO in the SFR-M ⋆ plane and we show that the higher sSFR of distant galaxies is directly related to their larger gas fractions.

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