- ID:
- ivo://CDS.VizieR/J/A+A/608/A48
- Title:
- HAE229 CO (1-0) ATCA datacube
- Short Name:
- J/A+A/608/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is not yet known if the properties of molecular gas in distant protocluster galaxies are significantly acted by their environment as galaxies are in local clusters. Through a deep, 64 hours of effective on-source integration with the Australian Telescope Compact Array (ATCA), we discovered a massive, M_mol_=2.0+/-0.2x0^11^M_{sun}_, extended, ~40kpc, CO(1-0)-emitting disk in the protocluster surrounding the radio galaxy, MRC1138-262. The galaxy, at z_CO_=2.1478, is a clumpy, massive disk galaxy, M*~5x10^11^M_{sun}_, which lies 250kpc in projection from MRC1138-262 and is a known H{alpha} emitter, named HAE229. This source has a molecular gas fraction of ~30%. The CO emission has a kinematic gradient along its major axis, centered on the highest surface brightness rest-frame optical emission, consistent with HAE229 being a rotating disk. Surprisingly, a significant fraction of the CO emission lies outside of the UV/optical emission. In spite of this, HAE229 follows the same relation between star-formation rate and molecular gas mass as normal field galaxies. HAE229 is the first CO(1-0) detection of an ordinary, star-forming galaxy in a protocluster.We compare a sample of cluster members at z>0.4 that are detected in low-order CO transitions, with a similar sample of sources drawn from the field.We confirm findings that the CO-luminosity and full-width at half maximum (FWHM) are correlated in starbursts and show that this relation is valid for normal high-z galaxies as well as for those in overdensities. We do not find a clear dichotomy in the integrated Schmidt-Kennicutt relation for protocluster and field galaxies. Our results suggest that environment does not have an impact on the "star-formation electronic efficiency" or the molecular gas content of high-redshift galaxies. Not finding any environmental dependence in these characteristics, especially for such an extended CO disk, suggests that environmentally-specific processes such as ram pressure stripping do not operate electronic efficiently in (proto)clusters.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/877/103
- Title:
- Half-mass radii for ~7000 galaxies at 1.0<=z<=2.5
- Short Name:
- J/ApJ/877/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial mass-to-light ratio gradients cause the half-mass and half-light radii of galaxies to differ, potentially biasing studies that use half-light radii. Here we present the largest catalog to date of galaxy half-mass radii at z>1: 7006 galaxies in the CANDELS fields at 1.0<=z<=2.5. The sample includes both star-forming and quiescent galaxies with stellar masses 9.0<=log(M_*_/M_{sun}_)<=11.5. We test three methods for calculating half-mass radii from multiband PSF-matched Hubble Space Telescope (HST) imaging: two based on spatially resolved spectral energy distribution modeling, and one that uses a rest-frame color profile. All three methods agree, with scatter <~0.3dex. In agreement with previous studies, most galaxies in our sample have negative color gradients (the centers are redder than the outskirts, and r_e,mass_<r_e,light_). We find that color gradient strength has significant trends with increasing stellar mass, half-light radius, U-V color, and stellar mass surface density. These trends have not been seen before at z>1. Furthermore, color gradients of star-forming and quiescent galaxies show a similar redshift evolution: they are flat at z>~2, then steeply decrease as redshift decreases. This affects the galaxy mass-size relation. The normalizations of the star-forming and quiescent r_mass_-M_*_ relations are 10%-40% smaller than the corresponding r_light_-M_*_ relations; the slopes are ~0.1-0.3dex shallower. Finally, the half-mass radii of star-forming and quiescent galaxies at M_*_=10^10.5^M_{sun}_ only grow by ~1% and ~8% between z~2.25 and z~1.25. This is significantly less than the ~37% and ~47% size increases found when using the half-light radius.
- ID:
- ivo://CDS.VizieR/J/ApJS/178/247
- Title:
- H{alpha} and [NII] survey in local 11 Mpc
- Short Name:
- J/ApJS/178/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a broader effort to characterize the population of star-forming galaxies in the local universe, we have carried out an H{alpha}+[NII] imaging survey for an essentially volume-limited sample of galaxies within 11Mpc of the Milky Way. This first paper describes the design of the survey, the observation, data processing, and calibration procedures, and the characteristics of the galaxy sample. The main product of the paper is a catalog of integrated H{alpha} fluxes, luminosities, and equivalent widths for the galaxies in the sample. We briefly discuss the completeness properties of the survey and compare the distribution of the sample and its star formation properties to other large H{alpha} imaging surveys. These data form the foundation for a series of follow-up studies of the star formation properties of the local volume, and the properties and duty cycles of star formation bursts in dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/506/3079
- Title:
- Halpha and other SFR indicators
- Short Name:
- J/MNRAS/506/3079
- Date:
- 18 Jan 2022 13:46:29
- Publisher:
- CDS
- Description:
- We present new H{alpha} photometry for the Star Formation Reference Survey (SFRS), a representative sample of star-forming galaxies in the local Universe. Combining these data with the panchromatic coverage of the SFRS, we provide calibrations of H{alpha}-based star-formation rates (SFRs) with and without correction for the contribution of [NII] emission. We consider the effect of extinction corrections based on the Balmer decrement, infrared excess, and spectral energy distribution (SED) fits. We compare the SFR estimates derived from SED fits, polycyclic aromatic hydrocarbons, hybrid indicators such as 24um+H{alpha}, 8um+H{alpha}, FIR+FUV, and H{alpha} emission for a sample of purely star-forming galaxies. We provide a new calibration for 1.4GHz-based SFRs by comparing to the H{alpha} emission, and we measure a dependence of the radio-to-H{alpha} emission ratio based on galaxy stellar mass. Active galactic nuclei introduce biases in the calibrations of different SFR indicators but have only a minimal effect on the inferred SFR densities from galaxy surveys. Finally, we quantify the correlation between galaxy metallicity and extinction.
- ID:
- ivo://CDS.VizieR/J/ApJ/744/44
- Title:
- H{alpha} and UV fluxes in nearby galaxies
- Short Name:
- J/ApJ/744/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We consider the effects of non-constant star formation histories (SFHs) on H{alpha} and GALEX far-ultraviolet (FUV) star formation rate (SFR) indicators. Under the assumption of a fully populated Chabrier initial mass function (IMF), we compare the distribution of H{alpha}-to-FUV flux ratios from ~1500 simple, periodic model SFHs with observations of 185 galaxies from the Spitzer Local Volume Legacy survey. We find a set of SFH models that are well matched to the data, such that more massive galaxies are best characterized by nearly constant SFHs, while low-mass systems experience burst amplitudes of ~30 (i.e., an increase in the SFR by a factor of 30 over the SFR during the inter-burst period), burst durations of tens of Myr, and periods of ~250 Myr; these SFHs are broadly consistent with the increased stochastic star formation expected in systems with lower SFRs. We analyze the predicted temporal evolution of galaxy stellar mass, R-band surface brightness, H{alpha}-derived SFR, and blue luminosity, and find that they provide a reasonable match to observed flux distributions. We find that our model SFHs are generally able to reproduce both the observed systematic decline and increased scatter in H{alpha}-to-FUV ratios toward low-mass systems, without invoking other physical mechanisms.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/599
- Title:
- H{alpha} and UV SFR in the local volume
- Short Name:
- J/ApJ/706/599
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a complete sample of ~300 star-forming galaxies within 11Mpc of the Milky Way, we evaluate the consistency between star formation rates (SFRs) inferred from the far ultraviolet (FUV) non-ionizing continuum and H{alpha} nebular emission, assuming standard conversion recipes in which the SFR scales linearly with luminosity at a given wavelength. Our analysis probes SFRs over 5 orders of magnitude, down to ultra-low activities on the order of ~10^-4^M_{sun}_/yr. The data are drawn from the 11Mpc H{alpha} and Ultraviolet Galaxy Survey (11HUGS), which has obtained H{alpha} fluxes from ground-based narrowband imaging, and UV fluxes from imaging with GALEX.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/495
- Title:
- Halpha Catalogue of HCG Galaxies
- Short Name:
- J/A+AS/137/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H{alpha} photometry for a sample of 95 galaxies in Hickson Compact Groups (Cat. <VII/213>) obtained from observations of 31 groups. The Catalogue lists isophotal and adaptive aperture (Kron aperture) flux measurements for about 75% of the accordant galaxies inside the observed HCGs, 22 out of which are upper limits. Non standard data reduction procedures have been used to obtain the continuum subtracted H{alpha} images for each HCG of the target sample. Flux calibration has also been performed in order to obtain H{alpha} luminosities for the whole sample. Both the data reduction and calibration procedures are carefully described in the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A102
- Title:
- Halpha data cube of Stephan's Quintet
- Short Name:
- J/A+A/629/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stephan's Quintet (SQ), the prototypical compact group of galaxies in the local Universe, has been observed with the imaging Fourier transform spectrometer SITELLE, attached to the Canada-France-Hawaii- Telescope, to perform a deep search for intergalactic star-forming emission. In this paper we present the extended ionised gaseous structures detected and analyse their kinematical properties. The large field of view (11'x11') and the spectral ranges of SITELLE have allowed a thorough study of the entire galaxy system, its interaction history and the main properties of the ionised gas. The observations have revealed complex three-dimensional strands in SQ seen for the first time, as well as the spatially resolved velocity field for a new SQ dwarf galaxy (M82-like) and the detailed spectral map of NGC7320c, confirming its AGN nature. A total of 175 SQ Halpha emission regions have been found, 22 of which present line profiles with at least two kinematical components. We studied 12 zones and 28 sub-zones in the SQ system in order to define plausible physical spatial connections between its different parts in the light of the kinematical information gathered. In this respect we have found five velocity systems in SQ: i) v=[5600-5900]km/s associated with the new intruder and the southern debris region; ii) v=[5900-6100]km/s, associated with the north starburst A and south starburst A and the strands connected to these zones; iii) v=[6100-6600]km/s, associated with the strands from the large-scale shock region (LSSR); iv) v=[6600-6800]km/s, associated with the young tidal tail, the starburst A (SQA), NGC7319, and the NGC7319 north lobe; and v) v=[6800-7000]km/s, associated with the strands seen connecting LSSR with SQA. We fail to detect ionised gas emission in the old tail, neither in the vicinity of NGC7318A nor in NGC7317, and the connection between NGC7319 north lobe and SQA cannot be confirmed. Conversely, a clear gaseous bridge has been confirmed both spatially and kinematically between the LSSR zone and the NGC7319 AGN nucleus. Finally, a larger scale, outer rim winding the NGC7318B/A system clockwise north-west to south-east has been highlighted in continuum and in H{alpha}. This structure may be reminiscent of a sequence of a previously proposed scenario for SQ a sequence of individual interactions.
- ID:
- ivo://CDS.VizieR/J/AJ/134/2474
- Title:
- H{alpha} emission-line stars in 7 dwarfs galaxies
- Short Name:
- J/AJ/134/2474
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a search for H{alpha} emission-line stars in M31, M33, and seven dwarfs in or near the Local Group (IC 10, NGC 6822, WLM, Sextans B, Sextans A, Pegasus, and the Phoenix dwarf) using interference filter imaging with the KPNO and CTIO 4m telescopes and Mosaic cameras. The survey is aimed primarily at identifying new luminous blue variables (LBVs) from their spectroscopic similarity to known LBVs, avoiding the bias toward photometric variability, which may require centuries to manifest itself if LBVs go through long quiescent periods. Follow-up spectroscopy with WIYN confirms that our survey detected a wealth of stars whose spectra are similar to the known LBVs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/1977
- Title:
- H-alpha emitters in/towards USS 1558
- Short Name:
- J/MNRAS/473/1977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out deep H{alpha} narrowband imaging with 10h net integrations towards the young protocluster, USS1558-003 at z=2.53 with the Subaru Telescope. This system is composed of four dense groups with massive local overdensities, traced by 107 H{alpha} emitters (HAEs) with stellar masses and dust-corrected star formation rates down to 1x10^8^M_{sun}_ and 3M_{sun}_/yr, respectively. We have investigated the environmental dependence of various physical properties within the protocluster by comparing distributions of HAEs in higher and lower densities with a standard Kolmogorov-Smirnov test. At 97 per cent confidence level, we find enhanced star formation across the star-forming main sequence of HAEs living in the most extreme 'supergroup', corresponding to the top quartile of overdensities. Furthermore, we derive distribution functions of H{alpha} luminosity and stellar mass in group and intergroup regions, approximately corresponding to 30 and 8 times higher densities than the general field. As a consequence, we identify 0.7 and 0.9dex higher cut-offs in H{alpha} luminosity and stellar mass functions in the dense groups, respectively. On the other hand, HAEs in the intergroup environment of the protocluster show similar distribution functions to those of field galaxies despite residing in significant overdensities. In the early phase of cluster formation, as inferred from our results, the densest parts in the protocluster have had an accelerated formation of massive galaxies. We expect that these eventually grow and transform into early-type galaxies at the bright end of the red sequence as seen in present-day rich clusters of galaxies.
