Studies of galaxies in voids

Pustilnik, S. A.; Martin, Jean‐Michel; Huchtmeier, W. K.; Brosch, Noah; Lipovetsky, V. A.; Richter, G. M.

doi:10.1051/0004-6361:20020591

Cited by 46 publications

(50 citation statements)

References 61 publications

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“…Compared to previous H I surveys with the NRT (van Driel et al 2001;Pustilnik et al 2002;Monnier Ragaigne et al 2003), our detection threshold and line strength sensitivities have been lowered by a factor 5, from 2 Jy km/s to 0.4 Jy km/s, for comparable, total integration times (1 ÷ 3 hours per target). One can notice also that the achieved sensitivity limits, in term of line strength P * 21 ( Table ?…”

Section: H I Signal Searchcontrasting

confidence: 55%

On sky characterization of the BAORadio wide band digital backend

et al. 2015

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We have observed regions of three galaxy clusters at z ∼ [0.06 ÷ 0.09] (Abell85, Abell1205, Abell2440), as well as calibration sources with the Nançay radiotelescope (NRT) to search for 21 cm emission and fully characterize the FPGA based BAORadio digital backend. The total observation time of few hours per source have been distributed over few months, from March 2011 to January 2012, due to scheduling constraints of the NRT, which is a transit telescope. Data have been acquired in parallel with the NRT standard correlator (ACRT) back-end, as well as with the BAORadio data acquisition system. The latter enables wide band instantaneous observation of the [1250, 1500] MHz frequency range, as well as the use of powerful RFI mitigation methods thanks to its fine time sampling. A number of questions related to instrument stability, data processing and calibration are discussed. We have obtained the radiometer curves over the integration time range [0.01,10 000] seconds and we show that sensitivities of few mJy over most of the wide frequency band can be reached with the NRT. It is clearly shown that in blind line search, which is the context of H I intensity mapping for Baryon Acoustic Oscillations, the new acquisition system and processing pipeline outperforms the standard one. We report a positive detection of 21 cm emission at 3σ -level from galaxies in the outer region of Abell85 at 1352 MHz (14400 km/s) corresponding to a line strength of 0.8 Jy km/s. We observe also an excess power around 1318 Mhz (21600 km/s), although at lower statistical significance, compatible with emission from Abell1205 galaxies. Detected radio line emissions have been cross matched with optical catalogs and we have derived hydrogen mass estimates.

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Section: H I Signal Searchcontrasting

confidence: 55%

On sky characterization of the BAORadio wide band digital backend

et al. 2015

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“…17 does not allow us to determine the Keplerian mass of the galaxy. Using the H i data given by Pustilnik et al (2002), we derive M H I = (9.6 ± 3.6) × 10 8 M and M H I = (8.1 ± 3.6) × 10 8 M for A and B, respectively, which are indicative of mass-to-luminosity ratios of M H I /L B = 0.75 and 0.59. The gas depletion timescales are 1.7 Gyr for A and 5.5 Gyr for B.…”

Section: Kinematics Of the Ionized Gasmentioning

confidence: 93%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

Esteban

2009

A&A

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Aims. We have performed a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show the presence of a substantial population of very young massive stars, most of them classified as Wolf-Rayet (WR) galaxies. In this paper, the second of the series, we present the results of the analysis of long-slit intermediate-resolution spectroscopy of star-formation bursts for 16 galaxies of our sample. Methods. We study the spatial localization of the WR stars in each galaxy. We analyze the excitation mechanism and derive the reddening coefficient, physical conditions, and chemical abundances of the ionized gas. We study the kinematics of the ionized gas to check the rotation/turbulence pattern of each system. When possible, tentative estimates of the Keplerian mass of the galaxies are calculated. Results. Aperture effects and the exact positioning of the slit onto the WR-rich bursts seem to play a fundamental role in their detection. We check that the ages of the last star-forming burst estimated using optical spectra agree with those derived from Hα imagery. Our analysis shows that a substantial fraction of the galaxies exhibit evidence of perturbed kinematics. With respect to the results found in individual galaxies, we remark the detection of objects with different metallicity and decoupled kinematics in Haro 15 and Mkn 1199, the detection of tidal streams in IRAS 08208+2816, Tol 9, and perhaps in SBS 1319+579, and the development of a merging process in both SBS 0926+606 A and Tol 1457-262. Conclusions. All of these results -in combination with those obtained in Paper I -reinforce the hypothesis that interactions with or between dwarf objects is a very important mechanism in triggering massive-star formation in starburst galaxies, especially in dwarf ones. It must be highlighted that only deep and very detailed observations -as presented in this paper -can provide clear evidences that these subtle interaction processes are taking place.

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“…The key properties which indicate these low-luminosity galaxies may be in the midst of an evolutionary transition from dI/BCD to dE include the following. (Roberts & Haynes 1994) and BCDs (Pustilnik et al 2002) and M H I /L B < 0.1 for dEs. Star formation can continue in our sample galaxies only for about another 10 9 years at their current rate, based on their H i content; in a few cases, inclusion of molecular gas will at most double this time (e.g., Jackson et al 1989;Gordon 1991).…”

Section: Introductionmentioning

confidence: 88%

Deep Optical Imaging of Starbursting “Transition” Dwarf Galaxies

Dellenbusch

Gallagher

Knezek³

et al. 2007

The Astronomical Journal

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A subgroup of dwarf galaxies have characteristics of a possible evolutionary transition between star-forming systems and dwarf ellipticals. These systems host significant starbursts in combination with smooth, elliptical outer envelopes, and small H i content; they are low on gas and unlikely to sustain high star-formation rates over significant cosmic time spans. We explore possible origins of such starburst "transition" dwarfs using moderately deep optical images. While galaxy-galaxy interactions could produce these galaxies, no optical evidence exists for tidal debris or other outer disturbances, and they also lack nearby giant neighbors which could supply recent perturbations. Colors of the outer regions indicate that star formation ceased >1 Gyr in the past, a longer time span than can be reasonably associated with the current starbursts. We consider mechanisms where the starbursts are tied either to interactions with other dwarfs or to the state of the interstellar medium, and discuss the possibility of episodic star-formation events associated with gas heating and cooling in low specific angular-momentum galaxies.

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Studies of galaxies in voids

Cited by 46 publications

References 61 publications

On sky characterization of the BAORadio wide band digital backend

On sky characterization of the BAORadio wide band digital backend

Massive star formation in Wolf-Rayet galaxies

Deep Optical Imaging of Starbursting “Transition” Dwarf Galaxies

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