We determine the intrinsic axial ratio distribution of 'gas' disks extremely faint M_B > -14.5 dwarf irregular galaxies. start with measured (beam corrected) apparent ratios in HI 21cm images galaxies observed as part Faint Irregular Galaxy GMRT Survey (FIGGS). Assuming that can be approximated oblate spheroids, obtained from distribution. use a couple methods to do this, and our final results are based on using Lucy's deconvolution algorithm. This method is constrained produce physically...

We revisit the HI size-mass (D$_{\rm HI}$-M$_{\rm HI}$) relation of galaxies with a sample more than 500 nearby covering over five orders magnitude in mass and ten $B$-band magnitudes. The is remarkably tight scatter $\sigma \sim$0.06 dex, or 14%. does not change as function galaxy luminosity, richness morphological type. linked to fact that dwarf spiral have homogenous radial profile surface density outer regions when radius normalised by D$_{\rm HI}$. early-type disk typically shallower...

The Faint Irregular Galaxies GMRT Survey (FIGGS) is a Giant Metrewave Radio Telescope (GMRT) based HI imaging survey of systematically selected sample extremely faint nearby dwarf irregular galaxies. primary goal FIGGS to provide comprehensive and statistically robust characterization the neutral inter-stellar medium properties faint, gas rich galaxies represent low-mass end population, with median M${\rm{_B\sim-13.0}}$ mass $\sim 3 \times 10^7$ M$_\odot$, extending baseline in luminosity...

Foreground removal is a major challenge for detecting the redshifted 21 cm neutral hydrogen (H i) signal from Epoch of Reionization. We have used 150 MHz Giant Metrewave Radio Telescope observations to characterize statistical properties foregrounds in four different fields view. The measured multifrequency angular power spectrum Cℓ(Δν) found values range 104–2 × 104 mK2 across 700 ≤ ℓ 2 and Δν 2.5 MHz, which consistent with model predictions where point sources are most dominant foreground...

XSS J12270-4859 is an X-ray binary associated with the Fermi LAT gamma-ray source 1FGL J1227.9-4852. In 2012 December, this underwent a transition where and optical luminosity dropped spectral signatures of accretion disc disappeared. We report discovery 1.69 millisecond pulsar (MSP), PSR J1227-4853, at dispersion measure 43.4 pc cm$^{-3}$ source, using GMRT 607 MHz. This demonstrates that, post-transition, system hosts active radio MSP. third after J1023+0038 J1824-2452I showing evidence...

We report results from a programme aimed at investigating the temperature of neutral gas in high-redshift damped Lyman α absorbers (DLAs). This involved (1) H i 21 cm absorption studies large sample DLAs towards radio-loud quasars, (2) very long baseline interferometric to measure low-frequency quasar core fractions, and (3) optical/ultraviolet spectroscopy determine DLA metallicities velocity widths low-ionization metal lines. Including literature data, our consists 37 with estimates...

We use observations from the Giant Metrewave Radio Telescope (GMRT) to measure atomic hydrogen gas content of star-forming galaxies at z = 0.24 (i.e. a look-backtime ~3 Gyr). The sample studied were selected Halpha-emitting field detected in narrow-band imaging survey with Subaru Telescope. Anglo-Australian was used obtain precise optical redshifts for these galaxies. then coadded HI 21 cm emission signal all within GMRT spectral line data cube. From 121 galaxies, we an average mass (2.26 +-...

Foreground subtraction is the biggest challenge for future redshifted 21 cm observations to probe reionization. We use a short GMRT observation at 153 MHz characterize statistical properties of background radiation across ~ one degree sub-arcminutes angular scales, and frequency band 5 with 62.5 kHz resolution. The statistic we visibility correlation function, or equivalently power spectrum C_l. present results obtained from using relatively unsophisticated, conventional data calibration...

We measure the neutral atomic hydrogen (H i) gas content of field galaxies at intermediate redshifts z ∼ 0.1 and ∼0.2 using 21-cm emission lines observed with Westerbork Synthesis Radio Telescope. In order to make high signal-to-noise ratio detections, an H i signal stacking technique is applied: spectra from multiple galaxies, optically selected by second Canadian Network for Observational Cosmology redshift survey project, are co-added average mass in two bins. calculate cosmic densities...

We use observations made with the Giant Metrewave Radio Telescope (GMRT) to probe neutral hydrogen (H i) gas content of field galaxies in VIMOS VLT Deep Survey (VVDS) 14h at z ≈ 0.32. Because H i emission from individual is too faint detect this redshift, we an spectral stacking technique using known optical positions and redshifts 165 our sample co-add their spectra thus obtain average mass galaxies. Stacked measurements show that ≳ 95 per cent found blue, star-forming Among these galaxies,...

We study the Kennicutt-Schmidt relation between average star formation rate and cold gas surface density in Hi dominated ISM of nearby spiral dwarf irregular galaxies. divide galaxies into grid cells varying from sub-kpc to tens kpc size. Grid-cell measurements low SFRs using H-alpha emission can be biased scatter may introduced because non-uniform sampling IMF or stochastically formation. In order alleviate these issues, we use far-ultraviolet trace SFR, sum up fluxes different bins with...

We present deep GMRT 21-cm absorption spectra of 10 damped Lyman-α systems (DLAs), which 8 are at redshifts . HI was detected in only one DLA, the absorber toward PKS 1629+12. This has been identified with a luminous spiral galaxy; spin temperature limit ( K) derived from our observations continues trend DLAs associated bright spirals having low temperatures. In seven remaining 9 systems, place strong lower limits on gas. combine this sample data taken literature to study properties all...

view Abstract Citations (124) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Fast, Low-Ionization Emission Regions and Other Microstructures in Planetary Nebulae Balick, Bruce ; Rugers, M. Terzian, Yervant Chengalur, Jayaram N. nebulae (PNs) have highly articulated structures, called 'microstructures', little of which has been explored with spectrophotometry at high spatial resolution. We report spectrophotometric observations microstructures...

We used observations from the Giant Metrewave Radio Telescope to measure atomic hydrogen gas content of 324 galaxies around galaxy cluster Abell 370 at a redshift z= 0.37 (a look-back time ∼4 billion years). The H i 21 cm emission these was measured by co-adding their signals using precise optical redshifts obtained with Anglo-Australian Telescope. average mass for all is (6.6 ± 3.5) × 109 M⊙, while 105 optically blue (19.0 6.5) M⊙. significant quantities found suggest that there has been...

We study the relationship between gas column density (derived from GMRT 21 cm data) and star formation rate surface publicly available GALEX for a sample of 23 extremely faint dwarf irregular galaxies drawn Faint Irregular Galaxy Survey (FIGGS). Our have median HI mass 2.8e07 solar masses blue magnitude -13.2. find that averaged over forming region disk lies below most estimates "threshold density" formation, average is also lower than would be expected "Kennicutt-Schmidt" law (Kennnicutt...

Abstract We have used the upgraded Giant Metrewave Radio Telescope to carry out a deep (117 on-source hours) L -band observation of Extended Groth Strip, measure average neutral hydrogen (H i ) mass and median star formation rate (SFR) star-forming galaxies, as well cosmic H density, at 0.2 < z 0.4. This was done by stacking 21 cm emission rest-frame 1.4 GHz radio continuum from 445 blue galaxies with M B ≤ −17 mean ≈ 0.34. The stacked signal is detected ≈7 σ significance, implying an ....

We compare the gas distribution, kinematics and current star formation in a sample of 10 very faint (-13.37 < M_B -9.55) dwarf galaxies. For 5 these galaxies we present fresh, high sensitivity, GMRT HI 21cm observations. all our construct maps column density at constant linear resolution ~300 pc; this forms an excellent data set to check for presence threshold formation. find that while (as traced by Halpha emission) is confined regions with relatively large (N_HI > (0.4 -1.7) X...

We present Giant Metrewave Radio Telescope (GMRT) observations for three (viz., DDO 68, SDSS J2104-0035 and UGC 772) of the six most metal-deficient actively star-forming galaxies known. Although there is a debate as to whether these are undergoing their first episode star formation or not, they `young' in sense that ISM chemically unevolved. In this regard, nearest equivalents young early Universe. All galaxies, we have observed, irregular HI morphologies kinematics, which interpret either...

Extremely metal-deficient (XMD) galaxies, by definition, have oxygen abundances \le 1/10 solar, and form a very small fraction of the local gas-rich, star-forming dwarf galaxy population. We examine their positions in luminousity-metallicity (L-Z) mass-metallicity (M-Z) planes, with respect to L-Z M-Z relations other viz., blue compact galaxies (BCGs) irregular (dI) galaxies. find that while metallicities some low-luminousity XMD are consistent those expected from relation, deviant....

We study Tully-Fisher relations for a sample that combines extremely faint (M_B > -14.0) galaxies along with bright (i.e. L_*) galaxies. Accurate (~ 10%) distances, I band photometry, and B-V colors are known the majority of in our sample. The drawn from Faint Irregular Galaxy GMRT survey (FIGGS), we have HI rotation velocities derived aperture synthesis observations all them. For galaxies, find even though median stellar masses comparable, mass correlates significantly better circular...

We have carried out deep, high velocity resolution, interferometric Galactic HI 21 cm absorption spectroscopy towards 32 compact extra-galactic radio sources with the Giant Metrewave Radio Telescope (GMRT) and Westerbork Synthesis (WSRT). The optical depth spectra for most root mean square noise values \lesssim 10^{-3} per 1 km/s channel are thus sufficiently sensitive to detect by warm neutral hydrogen column densities N_HI \gtrsim 10^{20} cm^{-2}, spin temperatures T_s \leq 5000 K, line...

Foreground removal is a challenge for 21-cm tomography of the high redshift Universe. We use archival GMRT data (obtained completely different astronomical goals) to estimate foregrounds at ~ 1. The statistic we cross power spectrum between two frequencies separated by \Delta{\nu} angular multipole l, or equivalently multi-frequency C_l(\Delta{\nu}). An earlier measurement C_l(\Delta{\nu}) using this had revealed presence oscillatory patterns along \Delta{\nu}, which turned out be severe...

We discuss physical conditions in Galactic neutral hydrogen based on deep, high velocity resolution interferometric HI 21 cm absorption spectroscopy towards 33 compact extra-galactic radio sources. The optical depth spectra have root-mean-square noise values \lesssim 10^{-3} per 1 km/s channel, i.e., sufficiently sensitive to detect by the warm medium (WNM). Comparing these with emission from Leiden-Argentine-Bonn (LAB) survey, we show that some of detected most sightlines must arise gas...