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991. Extragalactic radio sources polarization
ID:
ivo://CDS.VizieR/J/A+AS/135/571
Title:
Extragalactic radio sources polarization
Short Name:
J/A+AS/135/571
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present linear polarization measurements of 154 extragalactic radio sources at {lambda}6.3cm, as part of a continuing effort to expand and improve our Faraday rotation determinations of radio galaxies and quasars. The excellent telescope optics of the Effelsberg 100 m telescope at this wavelength, combined with a matrix method we applied for calibrating out all components of the instrumental polarization enables us to achieve better than average accuracy in the determinations of linear polarization degree and position angle. In the absence of thermal noise errors, these are repeatable to better than 0.2% and 0.1{deg} respectively, for the prime calibrator, 3C 286.
992. Extragalactic sources at 22 and 37GHz
ID:
ivo://CDS.VizieR/J/A+A/440/409
Title:
Extragalactic sources at 22 and 37GHz
Short Name:
J/A+A/440/409
Date:
21 Oct 2021
Publisher:
CDS
Description:
Long term monitoring results from 2001 to mid 2004 of quasar observations at 22 and 37GHz done at the Metsahovi radio observatory are presented. Approximately 10000 observations are published here.
993. Extragalactic sources at 22, 37 and 87GHz
ID:
ivo://CDS.VizieR/J/A+A/427/769
Title:
Extragalactic sources at 22, 37 and 87GHz
Short Name:
J/A+A/427/769
Date:
21 Oct 2021
Publisher:
CDS
Description:
Long term monitoring results from mid 1995 to the end of 2000 of quasar observations at 22, 37 and 87GHz done at the Metsahovi radio observatory are presented. Approximately 15700 observations are published here.
994. Extragalactic star-forming regions
ID:
ivo://CDS.VizieR/J/AZh/94/648
Title:
Extragalactic star-forming regions
Short Name:
J/AZh/94/648
Date:
21 Oct 2021
Publisher:
CDS
Description:
The relationships between atomic and molecular hydrogen and dust of various sizes in extragalactic star-forming regions are considered, based on observational data from the Spitzer and Herschel infrared space telescopes, the Very Large Array (atomic hydrogen emission) and IRAM (CO emission). The source sample consists of approximately 300 star-forming regions in 11 nearby galaxies. Aperture photometry has been applied to measure the fluxes in eight infrared bands (3.6, 4.5, 5.8, 8, 24, 70, 100, and 160um), the atomic hydrogen 21 cm line, and CO (2-1) line. The parameters of the dust in the starforming regions were determined via synthetic-spectra fitting, such as the total dust mass, the fraction of polycyclic aromatic hydrocarbons (PAHs), etc. Comparison of the observed fluxes with the measured parameters shows that the relationships between atomic hydrogen, molecular hydrogen, and dust are different in low- and high-metallicity regions. Low-metallicity regions contain more atomic gas, but less molecular gas and dust, including PAHs. The mass of dust constitutes about 1% of the mass of molecular gas in all regions considered. Fluxes produced by atomic and molecular gas do not correlate with the parameters of the stellar radiation, whereas the dust fluxes grow with increasing mean intensity of stellar radiation and the fraction of enhanced stellar radiation. The ratio of the fluxes at 8 and 24um, which characterizes the PAH content, decreases with increasing intensity of the stellar radiation, possibly indicating evolutionary variations of the PAH content. The results confirm that the contribution of the 24um emission to the total IR luminosity of extragalactic star-forming regions does not depend on the metallicity.
995. Extragal. radio sources at 22, 37 and 87GHz
ID:
ivo://CDS.VizieR/J/A+AS/132/305
Title:
Extragal. radio sources at 22, 37 and 87GHz
Short Name:
J/A+AS/132/305
Date:
21 Oct 2021
Publisher:
CDS
Description:
Over 13500 continuum observations of extragalactic sources are presented. These observations of 157 sources at 22, 37 and 87GHz more than doubles the millimeter observations of these sources. The data are between 1990.5 and 1995.5, and combined with our earlier published data form a 15 year database.
996. Extreme emission line galaxies at z<~0.05
ID:
ivo://CDS.VizieR/J/ApJ/847/38
Title:
Extreme emission line galaxies at z<~0.05
Short Name:
J/ApJ/847/38
Date:
21 Oct 2021
Publisher:
CDS
Description:
Searching for extreme emission line galaxies allows us to find low-mass metal-poor galaxies that are good analogs of high redshift Ly{alpha} emitting galaxies. These low-mass extreme emission line galaxies are also potential Lyman-continuum leakers. Finding them at very low redshifts (z<~0.05) allows us to be sensitive to even lower stellar masses and metallicities. We report on a sample of extreme emission line galaxies at z<~0.05 (blueberry galaxies). We selected them from SDSS broadband images on the basis of their broadband colors and studied their properties with MMT spectroscopy. From the entire SDSS DR12 photometric catalog, we found 51 photometric candidates. We spectroscopically confirm 40 as blueberry galaxies. These blueberries are dwarf starburst galaxies with very small sizes (<1kpc) and very high ionization ([OIII]/[OII]~10-60). They also have some of the lowest stellar masses (log(M/M_{sun}_)~6.5-7.5) and lowest metallicities (7.1<12+log(O/H)<7.8) of starburst galaxies. Thus, they are small counterparts to green pea galaxies and high redshift Ly{alpha} emitting galaxies.
997. Extreme emission-line galaxies in CANDELS
ID:
ivo://CDS.VizieR/J/ApJ/742/111
Title:
Extreme emission-line galaxies in CANDELS
Short Name:
J/ApJ/742/111
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify an abundant population of extreme emission-line galaxies (EELGs) at redshift z~1.7 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). Sixty-nine EELG candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared broadband magnitudes. Supported by spectroscopic confirmation of strong [OIII] emission lines - with rest-frame equivalent widths ~1000{AA} - in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are galaxies with ~10^8^M_{sun}_ in stellar mass, undergoing an enormous starburst phase with M_*_/(dM/dt)_*_ of only ~15Myr. These bursts may cause outflows that are strong enough to produce cored dark matter profiles in low-mass galaxies. The individual star formation rates and the comoving number density (3.7x10^-4^Mpc^-3^) can produce in ~4Gyr much of the stellar mass density that is presently contained in 10^8^-10^9^M_{sun}_ dwarf galaxies. Therefore, our observations provide a strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z>1.
998. Extremely Isolated Galaxies. II.
ID:
ivo://CDS.VizieR/J/MNRAS/469/347
Title:
Extremely Isolated Galaxies. II.
Short Name:
J/MNRAS/469/347
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have selected a sample of 41 extremely isolated galaxies (EIGs) from the local Universe using both optical and HI Arecibo Legacy Fast ALFA survey redshifts. Narrow-band H{alpha} and wide-band imaging along with public data were used to derive star formation rates (SFRs), star formation histories and morphological classifications for the EIGs. We have found that the extreme isolation of the EIGs does not affect considerably their star formation compared to field galaxies. EIGs are typically 'blue cloud' galaxies that fit the 'main sequence of star-forming galaxies' and may show asymmetric star formation and strong compact star-forming regions. We discovered surprising environmental dependences of the HI content, M_HI_, and of the morphological type of EIGs; the most isolated galaxies (of subsample EIG-1) have lower M_HI_ on average (with 2.5{sigma} confidence) and a higher tendency to be early types (with 0.94 confidence) compared to the less isolated galaxies of subsample EIG-2. To the best of our knowledge, this is the first study that finds an effect in which an isolated sample shows a higher fraction of early types compared to a less isolated sample. Both early-type and late-type EIGs follow the same colour-to-M_*_, SFR-to-M_*_ (main sequence) and M_HI_-to-M_*_ relations. This indicates that the mechanisms and factors governing star formation, colour and the M_HI_-to-M_*_ relation are similar in early-type and late-type EIGs, and that the morphological type of EIGs is not governed by their M_HI_ content, colour or SFR.
999. Extremely metal-poor galaxies in SDSS. II.
ID:
ivo://CDS.VizieR/J/ApJ/819/110
Title:
Extremely metal-poor galaxies in SDSS. II.
Short Name:
J/ApJ/819/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
Extremely metal-poor (XMP) galaxies are defined to have a gas-phase metallicity smaller than a tenth of the solar value (12+log[O/H]<7.69). They are uncommon, chemically and possibly dynamically primitive, with physical conditions characteristic of earlier phases of the universe. We search for new XMPs in the Sloan Digital Sky Survey (SDSS) in a work that complements Paper I (Morales-Luis+, 2011, J/ApJ/743/77). This time, high electron temperature objects are selected; metals are a main coolant of the gas, so metal-poor objects contain high-temperature gas. Using the algorithm k-means, we classify 788677 spectra to select 1281 galaxies that have particularly intense [OIII]{lambda}4363 with respect to [OIII]{lambda}5007, which is a proxy for high electron temperature. The metallicity of these candidates was computed using a hybrid technique consistent with the direct method, rendering 196 XMPs. A less restrictive noise constraint provides a larger set with 332 candidates. Both lists are provided in electronic format. The selected XMP sample has a mean stellar mass around 10^8^M_{sun}_, with the dust mass ~10^3^M_{sun}_ for typical star-forming regions. In agreement with previous findings, XMPs show a tendency to be tadpole-like or cometary. Their underlying stellar continuum corresponds to a fairly young stellar population (<1Gyr), although young and aged stellar populations coexist at the low-metallicity starbursts. About 10% of the XMPs show large N/O. Based on their location in constrained cosmological numerical simulations, XMPs have a strong tendency to appear in voids and to avoid galaxy clusters. The puzzling 2%-solar low-metallicity threshold exhibited by XMPs remains.
1000. Extremely metal-poor (XMP) galaxies in SDSS
ID:
ivo://CDS.VizieR/J/ApJ/743/77
Title:
Extremely metal-poor (XMP) galaxies in SDSS
Short Name:
J/ApJ/743/77
Date:
21 Oct 2021
Publisher:
CDS
Description:
We carry out a systematic search for extremely metal-poor (XMP) galaxies in the spectroscopic sample of Sloan Digital Sky Survey (SDSS) data release 7 (DR7). The XMP candidates are found by classifying all the galaxies according to the form of their spectra in a region 80{AA} wide around H{alpha}. Due to the data size, the method requires an automatic classification algorithm. We use k-means. Our systematic search renders 32 galaxies having negligible [NII] lines, as expected in XMP galaxy spectra. Twenty-one of them have been previously identified as XMP galaxies in the literature - the remaining 11 are new. This was established after a thorough bibliographic search that yielded only some 130 galaxies known to have an oxygen metallicity 10 times smaller than the Sun (explicitly, with 12+log(O/H)<=7.65). XMP galaxies are rare; they represent 0.01% of the galaxies with emission lines in SDSS/DR7. Although the final metallicity estimate of all candidates remains pending, strong-line empirical calibrations indicate a metallicity about one-tenth solar, with the oxygen metallicity of the 21 known targets being 12+log(O/H)~7.61+/-0.19. Since the SDSS catalog is limited in apparent magnitude, we have been able to estimate the volume number density of XMP galaxies in the local universe, which turns out to be (1.32+/-0.23)x10^-4^Mpc^-3^. The XMP galaxies constitute 0.1% of the galaxies in the local volume, or ~0.2% considering only emission-line galaxies. All but four of our candidates are blue compact dwarf galaxies, and 24 of them have either cometary shape or are formed by chained knots.