The H<scp>i</scp>Content of E+A Galaxies

Buyle, Pieter; Michielsen, D.; Rijcke, S. De; Pisano, D. J.; Dejonghe, Herwig; Freeman, K. C.

doi:10.1086/505633

Cited by 35 publications

(62 citation statements)

References 29 publications

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“…A small but significant fraction of E+A galaxies have optical tidal features, which are indicative of a merger event only 0.5−1 Gyr ago (e.g., Zabludoff et al 1996;Blake et al 2004). Furthermore, Buyle et al (2006) obtained HI observations of a sample of E+A galaxies and showed that the total atomic gas content may not be consumed until a galaxy reaches its post-starburst phase.…”

Section: Present State and Expected Future Evolution Of Ngc 4441mentioning

confidence: 99%

The molecular gas content of the advanced S+E merger NGC 4441

Juette

Aalto

Huettemeister³

2010

A&A

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Context. Despite their importance to galaxy evolution, mergers between a spiral and an elliptical (S+E mergers) have been poorly studied so far. NGC 4441 is a nearby candidate of an advanced remnant of such a merger, showing typical tidal structures such as an optical tail and two shells as well as two H i tails.Aims. Studying the molecular gas content provides clues about the impact of a recent merger event on the star formation. Simulations of S+E mergers yield conflicting predictions about both the strength and the extent of an induced starburst. Thus, observations of the amount and the distribution of the molecular gas, the raw material of star formation, are needed to understand the influence of the merger on the star formation history. Methods. 12 CO and 13 CO (1−0) and (2−1) observations were obtained using the Onsala Space Observatory 20 m and IRAM 30 m telescope as well as the Plateau de Bure interferometer. These data allow us to carry out a basic analysis of the molecular gas properties, such as estimates of the molecular gas mass, temperature, and density and the star formation efficiency. Results. The CO observations detect an extended molecular gas reservoir out to ∼4 kpc, with a total molecular gas mass of ∼5 × 10 8 M . Furthermore, high resolution imaging shows a central molecular gas feature, which is probably a rotating disc hosting most of the molecular gas (∼4 × 10 8 M ). This nuclear disc has a different sense of rotation to the large-scale H i structure, indicating a kinematically decoupled core. We modeled the state of the interstellar medium with the radiative transfer code RADEX, using the ratios of the 12 CO to 13 CO line strenghts. The results are consistent with a diffuse (n ≤ 10 3 cm −3 ) molecular medium with no significant indications of cold, dense cores of ongoing star formation. This is in agreement with the moderate star formation rate of 1−2 M yr −1 measured for NGC 4441. Assuming a constant star formation rate, the gas depletion time is τ = 4.8 × 10 8 yr. NGC 4441 might be a nearby candidate early-type galaxy with a dominant A-star population, a so-called E+A galaxy, which is in a post-starburst phase several 10 8 yr after a merger event.

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Section: Present State and Expected Future Evolution Of Ngc 4441mentioning

confidence: 99%

The molecular gas content of the advanced S+E merger NGC 4441

Juette

Aalto

Huettemeister³

2010

A&A

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“…To create a starburst, the gas density must be strongly enhanced, otherwise the self-regulation prevents large SFR variations. The availability of large amounts of gas alone is not sufficient for a starburst as the example of poststarburst E+A galaxies with a large amount of HI gas demonstrated (Buyle et al 2006).…”

Section: Comparison With "Full" Dwarf Galaxy Simulationsmentioning

confidence: 99%

Starbursts in isolated galaxies

Theis

Koeppen

2009

A&A

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Context. Starbursts and substantial variations in the star formation histories are a common phenomenon in galaxies. Although predominantly found in interacting galaxies, they also occur in isolated galaxies. Aims. We study the stability properties of isolated star-forming dwarf galaxies with the aim of identifying starburst modes. The impact of the stellar birth function, i.e. a spontaneous and an induced star formation mode, the initial mass function (IMF), the stellar feedback and the interstellar medium (ISM) model on the galactic star formation history are investigated. We especially focus on dynamically driven starbursts induced by stellar feedback. Methods. We apply a one-zone model for a star-gas system coupled by both mass and energy transfer. Additionally, we extend the network for active dynamical evolution. This allows for a coupling between the dynamical state of the galaxy and its internal properties, such as star formation activity or the thermal state of the ISM. Results. While the influence of the dynamics on the total star formation rate is strong, especially with nonlinear stellar birth functions, the coupling of the internal properties (gas temperature) on the dynamics is rather limited, because radiative cooling keeps the gas temperature well below the virial temperature. Because of short cooling and feedback timescales, the star formation rate is close to the equilibrium star formation rates. Quasi-periodic starbursts occur, because star formation follows the variations in the gas density induced by decaying virial oscillations. This behaviour is quite insensitive to the nature and the details of the stellar birth description, viz. whether spontaneous or induced star formation is considered or the IMF is varied. A second type of burst is found as an instability operating when the cooling may drop at very low densities with increasing temperature, in regimes beyond 10 4 K. Conclusions. Bursts of star formation occur during transitory phases, when dynamical equilibrium is established. Then they are quasiperiodic on the dynamical timescale. Because of short heating and cooling timescales, the star formation rate follows the equilibrium star formation rate corresponding to the actual gas density.

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“…Thus, these galaxies should be secure PSGs. For more details about the data reduction and analysis, we refer to Buyle et al (2006). These 20 PSGs reside at redshifts z ∼ 0.06-0.12 (observing PSGs at high redshifts would result in unworkably long integration times).…”

Section: Hi Observations Of Psgsmentioning

confidence: 99%

Post‐starburst galaxies and the transformation of blue into red galaxies

Rijcke¹,

Buyle

Pisano

et al. 2009

Astron Nachr

Self Cite

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We present deep single-dish radio observations of a sample of nearby post-starburst galaxies (0.05 < z < 0.1). About 50% of these post-starburst galaxies are detected at 21 cm, with H I masses of ˜ 109 M_ȯ, up to ˜ 1010 M_ȯ. These post-starburst galaxies are as gas-rich as spiral galaxies with comparable luminosities. There appears to exist no direct correlation between the amount of H I present in a post-starburst galaxy and its star formation rate as traced by radio continuum emission. Moreover, the end of the starburst clearly does not necessarily require the complete exhaustion of the neutral gas reservoir. High-resolution radio observations of one post-starburst binary system suggest that most of the neutral gas resides outside the stellar bodies of the galaxies. Most likely, the gas was expelled by supernova and/or AGN feedback. This effectively stops star formation, even though copious amounts of diffuse neutral gas remain in the immediate vicinity. This remaining H I reservoir may eventually lead to further episodes of star formation. This may indicate that some post-starbursts are observed in the inactive phase of the star formation duty cycle

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The HiContent of E+A Galaxies

Cited by 35 publications

References 29 publications

The molecular gas content of the advanced S+E merger NGC 4441

The molecular gas content of the advanced S+E merger NGC 4441

Starbursts in isolated galaxies

Post‐starburst galaxies and the transformation of blue into red galaxies

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