Dense molecular gas in a sample of LIRGs and ULIRGs: The low-redshift connection to the huge high-redshift starbursts and AGNs

Graciá-Carpio, J.; García‐Burillo, S.; Planesas, P.

doi:10.1007/978-1-4020-6935-2_59

Cited by 3 publications

(5 citation statements)

References 28 publications

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“…4a we can see that SFE dense increases with L FIR from normal galaxies to LIRGs & ULIRGs and high-z objects. This result confirms that SFE dense is higher in high-z galaxies compared to normal galaxies (Graciá-Carpio et al 2008;Gao et al 2007;Riechers et al 2007) and clearly extends this trend for the first time to the luminosity range of local universe LIRGs and ULIRGs. An orthogonal regression fit to the full sample of galaxies, excluding (lower or upper) limits, gives (solid line in Fig.…”

Section: Samplesupporting

confidence: 76%

“…In this paper we present new observations made with the IRAM 30 m telescope of the J = 1−0 and 3-2 lines of HCN and HCO + used to probe the dense molecular gas content of a sample of 17 LIRGs and ULIRGs. Preliminary results of this work were published by Graciá-Carpio et al (2008). These observations, that complement the first HCO + survey published by Graciá-Carpio et al (2006, hereafter GC06) of LIRGs and ULIRGs, are used to derive a new version of the power law describing the correlation between L FIR and L HCN(1−0) from normal galaxies (L FIR < 10 11 L ) to high-z galaxies.…”

Section: Introductionmentioning

confidence: 82%

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Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies

Graciá-Carpio

García‐Burillo

Planesas

et al. 2007

A&A

163

202

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We present new observations made with the IRAM 30 m telescope of the J = 1−0 and 3-2 lines of HCN and HCO + used to probe the dense molecular gas content in a sample of 17 local luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs). These observations have allowed us to derive an updated version of the power law describing the correlation between the FIR luminosity (L FIR ) and the HCN(1−0) luminosity (L HCN(1−0) ) of local and high-redshift galaxies. We present the first clear observational evidence that the star formation efficiency of the dense gas (SFE dense ), measured as the L FIR /L HCN(1−0) ratio, is significantly higher in LIRGs and ULIRGs than in normal galaxies, a result that has also been found recently in high-redshift galaxies. This may imply a statistically significant turn upward in the Kennicutt-Schmidt law derived for the dense gas at L FIR ≥ 10 11 L . We used a one-phase large velocity gradient (LVG) radiative transfer code to fit the three independent line ratios derived from our observations. The results of this analysis indicate that the [HCN]/[HCO + ] abundance ratios could be up to one order of magnitude higher than normal in a significant number of the LIRGs and ULIRGs in our sample. An overabundance of HCN at high L FIR implies that the reported trend in the L FIR /L HCN ratio as a function of L FIR would be underestimating a potentially more dramatic change of the SFE dense . Results obtained with two-phase LVG models corroborate that the L HCN(1−0) -to-M dense conversion factor must be lowered at high L FIR . We discuss the implications of these findings for the use of HCN as a tracer of the dense molecular gas in local and high-redshift luminous infrared galaxies.

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Section: Samplesupporting

confidence: 76%

Section: Introductionmentioning

confidence: 82%

Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies

Graciá-Carpio

García‐Burillo

Planesas

et al. 2007

A&A

163

202

View full text Add to dashboard Cite

show abstract

“…Lintott & Viti, 2006;Meijerink et al, 2013). At least some evidence for this has been seen by Krips et al (2008) and Graciá-Carpio et al (2008) in nearby active systems.…”

Section: Physics Learned From the Milky Way And Local Galaxiesmentioning

confidence: 87%

“…There may be some indication of sub-linear SFR law slopes for very high effective density tracers (e.g. Bussmann et al, 2008;Graciá-Carpio et al, 2008;Bayet et al, 2009), though larger samples are most certainly necessary. (2) Very high density systems (such as SMGs, or galactic nuclei) should have a super-linear SFR-HCN (J=1-0) relation (Narayanan et al, 2008a).…”

Section: Physics Learned From the Milky Way And Local Galaxiesmentioning

confidence: 99%

Dusty star-forming galaxies at high redshift

2014

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Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10 13 L with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrared instrumentation in recent years, both spacebased and ground-based, has led to the detection of nearly a million DSFGs, yet our understanding of the underlying astrophysics that govern the start and end of the dusty starburst phase is still in nascent stage. This review is aimed at summarizing the current status of DSFG studies, focusing especially on the detailed characterization of the bestunderstood subset (submillimeter galaxies, who were summarized in the last review of this field over a decade ago, Blain et al. 2002), but also the selection and characterization of more recently discovered DSFG populations. We review DSFG population statistics, their physical properties including dust, gas and stellar contents, their environments, and current theoretical models related to the formation and evolution of these galaxies.

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“…CO data are gathered from single-dish maps/observations of galaxies (e.g., [25,26]). Most of our HCN data come from the systematic survey of GS04a, with a few from sparse sampling of the other papers [16][17][18]27].…”

Section: Sample and Datamentioning

confidence: 99%

The global star formation law of galaxies revisited in the radio continuum

Liu

Gao

2012

Sci. China Phys. Mech. Astron.

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We study the global star formation law, the relation between the gas and star formation rate (SFR) in a sample of 130 local galaxies with infrared (IR) luminosities spanning over three orders of magnitude (10 9 -10 12 L  ), which includes 91 normal spiral galaxies and 39 (ultra)luminous IR galaxies [(U)LIRGs]. We derive their total (atomic and molecular) gas and dense molecular gas masses using newly available HI, CO and HCN data from the literature. The SFR of galaxies is determined from total IR (8-1000 m) and 1.4 GHz radio continuum (RC) luminosities. The galaxy disk sizes are defined by the de-convolved elliptical Gaussian FWHM of the RC maps. We derive the galaxy disk-averaged SFRs and various gas surface densities, and investigate their relationships. We find that the galaxy disk-averaged surface density of dense molecular gas mass has the tightest correlation with that of SFR (scatter ~0.26 dex), and is linear in log-log space (power-law slope of N=1.03±0.02) across the full galaxy sample. The correlation between the total gas and SFR surface densities for the full sample has a somewhat larger scatter (~0.48 dex), and is best fit by a power-law with slope 1.45±0.02. However, the slope changes from ~1 when only normal spirals are considered, to ~1.5 when more and more (U)LIRGs are included in the fitting. When different CO-to-H 2 conversion factors are used to infer molecular gas masses for normal galaxies and (U)LIRGs, the bi-modal relations claimed recently in CO observations of high-redshift galaxies appear to also exist in local populations of star-forming galaxies. galaxies: evolation, galaxies: ISM, radio lines: galaxies, stars: fromation PACS number(s): 98.62.Ai, 98.58.D6, 98.54.Ep, 98.52.Nr Citation:Liu L J, Gao Y. The global star formation law of galaxies revisited in the radio continuum.Understanding how stars form in galaxies is fundamentally one of the central questions in galactic and extragalactic astronomy, since star formation (SF) plays an integral part of the formation and evolution of galaxies. Studies of the so-called SF law, which relates the SF rate (SFR) to the density of the gas from which the stars form, have proven to be a fruitful way of approaching this problem (e.g., Kennicutt 1998, hereafter K98 [1] ). Schmidt (1959) [2] first introduced the notion of a general SF law by suggesting that the SFR volume density ( SFR ) varies with the interstellar gas volume density ( gas ) to the power n, i.e. SFR gas , n    where n~2. Under the assumption of a constant scale-height for the star-forming gas, this relation translates directly into an equivalent expression for the SFR and gas surface densities: SFR gas . N   K98 studied the global SF law in log surface densities space and found that a power-law index of N~1.4±0.2 provided a surprisingly tight parameterization of the data. These studies of the Kennicutt-Schmidt SF law (KS law) were among the first to highlight the importance of the gas density in regulating the SFR in star-forming galaxies, including luminous and ultralu...

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Dense molecular gas in a sample of LIRGs and ULIRGs: The low-redshift connection to the huge high-redshift starbursts and AGNs

Cited by 3 publications

References 28 publications

Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies

Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies

Dusty star-forming galaxies at high redshift

The global star formation law of galaxies revisited in the radio continuum

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