A CONSTANT MOLECULAR GAS DEPLETION TIME IN NEARBY DISK GALAXIES

By F. Bigiel, A. Leroy, F. Walter, E. Brinks, W. D. de Blok, C. Kramer, Hans-Walter Rix, A. Schruba, K. Schuster, A. Usero and 1 more. 2011

271 citations recorded by the source corpus.

We combine new sensitive, wide-field CO data from the HERACLES survey with ultraviolet and infrared data from GALEX and Spitzer to compare the surface densities of H2, ΣH2, and the recent star formation rate, ΣSFR, over many thousands of positions in 30 nearby disk galaxies. We more than quadruple the size of the galaxy sample compared to previous work and include targets with a wide range of galaxy properties. Even though the disk galaxies in this study span a wide range of properties, we find a strong, and approximately linear correlation between ΣSFR and ΣH2 at our common resolution of 1 kpc. This implies a roughly constant median H2 consumption time, τH2Dep = ΣH2/ΣSFR, of ∼2.35 Gyr (including heavy elements) across our sample. At 1 kpc resolution, there is only a weak correlation between ΣH2 and τH2Dep over the range ΣH2 ≈ 5–100 M☉ pc−2, which is probed by our data. We compile a broad set of literature measurements that have been obtained using a variety of star formation tracers, sampling schemes, and physical scales and show that overall, these data yield almost exactly the same results, although with more scatter. We interpret these results as strong, albeit indirect evidence that star formation proceeds in a uniform way in giant molecular clouds in the disks of spiral galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/04e7a5543882fdfeee07f3f2f8a6d87372fe4d46

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Citations in the corpus

EVOLVING GRAVITATIONALLY UNSTABLE DISKS OVER COSMIC TIME: IMPLICATIONS FOR THICK DISK FORMATION (2011, background): “The modification from McKee & Krumholz (2010) is that we impose a lower limit on fH2 of 3%, motivated by the observation that even extremely low total gas surface density regions form stars at a rate consistent with a constant H2 depletion time (Bigiel et al. 2011).”
An uncertainty principle for star formation - I. Why galactic star formation relations break down below a certain spatial scale (2014, background): “Galactic star formation (SF) relations (e.g. Silk 1997; Kennicutt 1998; Elmegreen 2002; Bigiel et al. 2011) break down below a certain spatial scale (Schruba et al. 2010; Onodera et al. 2010; Liu et al. 2011).”
VALIDATION OF THE EQUILIBRIUM MODEL FOR GALAXY EVOLUTION TO z ∼ 3 THROUGH MOLECULAR GAS AND DUST OBSERVATIONS OF LENSED STAR-FORMING GALAXIES (2013, background): “In the local Universe, normal starforming galaxies have tdep(H2)∼ 1.5 Gyr (Leroy et al. 2008; Bigiel et al. 2011; Saintonge et al. 2011b, 2012).”
How sensitive are predicted galaxy luminosities to the choice of stellar population synthesis model (2013, background): “It is important to note that there are compelling observations from z =0 to z ∼ 3 supporting the new star formation implementation (Bigiel et al. 2011; Tacconi et al. 2013).”
TOWARD A COMPLETE ACCOUNTING OF ENERGY AND MOMENTUM FROM STELLAR FEEDBACK IN GALAXY FORMATION SIMULATIONS (2012, background): “Observations indicate that in the local universe tSF ∼ 2Gyr (Bigiel et al. 2011), which is a manifestation of the fact that observed galaxies convert their gas into stars quite inefficiently.”
THE KMOS3D SURVEY: DESIGN, FIRST RESULTS, AND THE EVOLUTION OF GALAXY KINEMATICS FROM 0.7 ⩽ z ⩽ 2.7 (2014, background): “The leading factor of 1.5 Gyr is a normalization to the typical depletion time observed in local galaxies (Leroy et al. 2008; Bigiel et al. 2011; Saintonge et al. 2012).”
Cosmic evolution of the atomic and molecular gas contents of galaxies (2011, unknown): “…hydrostatic pressure asΣH2/ΣHI = fmol/(fmol−1) = (Pext/P0) α. HerekB is Boltzmann’s constant and the values of νSF = 5.25 ± 2.5 × 10−10 yr−1 (Leroy et al. 2008; Bigiel et al. 2011),α = 0.92± 0.07 andlog(P0/kB[cm−3K]) = 4.54± 0.07 (Blitz & Rosolowsky 2006) are derived from fits to the observational…”
Is molecular gas necessary for star formation (2011, background): “…observations have demonstrated that on large scales within local galaxies, there is a surprisingly close correlation between the surface density of star formation, ΣSFR, and the surface density of molecular hydrogen, ΣH2 (see e.g. Wong & Blitz 2002; Leroy et al. 2008; Bigiel et al. 2008, 2011).”
MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES (2013, background): “Bigiel et al. (2011) demonstrated that a fixed ratio of CO to recent star formation rate remains a reasonable description of the ensemble of 30 galaxies.”
THE PdBI ARCSECOND WHIRLPOOL SURVEY (PAWS). I. A CLOUD-SCALE/MULTI-WAVELENGTH VIEW OF THE INTERSTELLAR MEDIUM IN A GRAND-DESIGN SPIRAL GALAXY (2013, background): “This clearly suggests a very close link between (massive) star formation and molecular gas which has also been demonstrated in recent studies of external galaxies to hold at kpcresolution (Leroy et al. 2013; Bigiel et al. 2008, 2011).”
THE ARECIBO LEGACY FAST ALFA SURVEY: THE GALAXY POPULATION DETECTED BY ALFALFA (2012, background): “Similarly, Bigiel et al. (2011) demonstrated a roughly constant H2 consumption time (ΣH2/ΣSFR ∼ 2.35 Gyr).”
What controls star formation in the central 500 pc of the Galaxy (2013, background): “In nearby disc galaxies, a simple proportionality of the SFRto the molecular mass is commonplace (Bigiel et al. 2008, 2011).”
The Formation and Destruction of Molecular Clouds and Galactic Star Formation (2015, background): “This may explain the so-called “depletion timescale” of molecular clouds that manifests observationlly in the Schmidt-Kennicutt Law (e.g., Bigiel et al. 2011; Lada etl.”
Galaxy formation in WMAP1 and WMAP7 cosmologies (2012, background): “Recent studies of galaxy-wide star formation suggest α ∼ 0.02 for present-day disk galaxies, although with a characteristic time which is determined by the atomicto-molecular transition rather than the disk orbital period (Bigiel et al. 2011).”
Physical Processes in the Interstellar Medium (2014, background): “Work by a number of groups has shown that on large scales, there is a tight correlation between the surface density of molecular gas and the surface density of star formation in spiral galaxies (Wong & Blitz, 2002; Leroy et al., 2008; Bigiel et al., 2008; Bigiel et al., 2011; Schruba et al., 2011).”
PHIBSS: MOLECULAR GAS CONTENT AND SCALING RELATIONS IN z ∼ 1–3 MASSIVE, MAIN-SEQUENCE STAR-FORMING GALAXIES (2012, background): “In summary, the galaxy integrated data of z~1-3 near-main sequence SFGs favor a near-linear molecular gas–star formation relation, similar to the findings at z~0 (Bigiel et al. 2008, 2011.”
Globular clusters as the relics of regular star formation in ‘normal’ high-redshift galaxies (2015, result): “The star formation rate per unit gasm ss (or alternatively the gas depletion timetdepl ≡ SFR/Mgas) is similar to that in nearby galaxies (tdepl ∼ 109 yr, Bigiel et al. 2011; Schruba et al. 2011; Tacconi et al. 2013; Fisher et al. 2014).”
PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions (2017, background): “The different conclusions could be caused in part by the narrower range of sSFRs covered in the HERACLES sample analyzed in Bigiel et al. (2008, 2011) and Leroy et al (2008, 2013), relative to COLDGASS.”
Galaxy evolution in groups and clusters: star formation rates, red sequence fractions and the persistent bimodality (2011, background): “…over which satellites remain active after infall (several Gyr), and likely shorter than molecular gas consumption time-scale (∼2.4 Gyr; e.g. Bigiel et al. 2011), because if satellite SFR simply were to fade slowly over this time-scale after infall, we would observe an excess of galaxies…”