- ID:
- ivo://CDS.VizieR/J/A+A/396/503
- Title:
- Spectra of blue compact galaxies
- Short Name:
- J/A+A/396/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper in a series studying the star formation rates, stellar components, metallicities, and star formation histories and evolution of a sample of blue compact galaxies. We analyzed spectral properties of 97 blue compact galaxies, obtained with the Beijing Astronomical Observatory (China) 2.16m telescope, with spectral range 3580{AA}-7400{AA}. We classify the spectra according to their emission lines: 13 of the total 97 BCG sample are non-emission line galaxies (non-ELGs); 10 have AGN-like emission (AGNs), and 74 of them are star-forming galaxies (SFGs). Emission line fluxes and equivalent widths, continuum fluxes, the 4000A Balmer break index and equivalent widths of absorption lines are measured from the spectra. Please find more detail information in http://optik2.mtk.nao.ac.jp/~xkong/bcg/
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- ID:
- ivo://CDS.VizieR/J/A+A/389/845
- Title:
- Spectra of blue compact galaxies
- Short Name:
- J/A+A/389/845
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Blue compact galaxies are compact objects that are dominated by intense star formation. Most of them have dramatically different properties compared to the Milky Way and many other nearby galaxies. Using the IRAS, HI data, and optical spectra, we wanted to measure the current star formation rates, stellar components, metallicities, and star formation histories and evolution of a large blue compact galaxy sample. We anticipate that our study will be useful as a benchmark for studies of emission line galaxies at high redshift. In the first paper of this series, we describe the selection, spectroscopic observation, data reduction and calibration, and spectrophotometric accuracy of a sample of 97 luminous blue compact galaxies. We present a spectrophotometric atlas of rest-frame spectra, as well as tables of the recession velocities and the signal-to-noise ratios. The recession velocities of these galaxies are measured with an accuracy of {delta}V<67km/s. The average signal-to-noise ratio of sample spectra is ~51. The spectral line strengths, equivalent widths and continuum fluxes are also measured for the same galaxies and will be analyzed in the next paper of this series.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A75
- Title:
- Spectra of 8 supergiants in nearby galaxies
- Short Name:
- J/A+A/562/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The role of episodic mass loss in massive star evolution is one of the outstanding questions of current stellar evolution theory. Episodic mass loss produces dust and therefore causes evolved massive stars to be very luminous in the mid-infrared and dim at optical wavelengths. We aim to increase the number of investigated luminous mid-IR sources to shed light on the late stages of these objects. To achieve this we explore mid-IR selection criteria to identity dusty evolved massive stars in two nearby galaxies. The method is based on mid-IR colors, using 3.6um and 4.5um photometry from archival Spitzer Space Telescope images of nearby galaxies and J-band from 2MASS. We apply our criteria to two nearby star-forming dwarf-irregular galaxies: Sextans A and IC 1613, selecting 8 targets, which we follow up with spectroscopy. Our spectral classification and analysis yielded the discovery of 2 M-type supergiants in IC 1613, 3 K-type supergiants and 1 candidate F-type giant in Sextans A, and 2 foreground M giants. We show that the proposed criteria provide an independent way for identifying dusty evolved massive stars, which can be extended to all nearby galaxies with available Spitzer/IRAC images at 3.6um and 4.5um.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A178
- Title:
- Spectra of 2 z>3 hot dust-obscured galaxies
- Short Name:
- J/A+A/646/A178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present the detection of H_2_O and OH+ emission in z>3 hot dust-obscured galaxies (Hot DOGs). Using ALMA Band-6 observations of two Hot DOGs, we have detected H_2_O(2_02_-1_11_) in W0149+2350, and H_2_O(3_12_-3_03_) and the multiplet OH+(1_1-0_1) in W0410-0913. These detections were serendipitous, falling within the side-bands of Band-6 observations aimed to study CO(9-8) in these Hot DOGs. We find that both sources have luminous H_2_O emission with line luminosities of L_H2O_>2.2x10^8^L_{sun}_ and L_H2O_=8.7x10^8^L_{sun}_ for W0149+2350 and W0410-0913, respectively. The H_2_O line profiles are similar to those seen for the neighbouring CO(9-8) line, with linewidths of FWHM~800-1000km/s. However, the H_2_O emission seems to be more compact than the CO(9-8). OH+ is detected in emission for W0410-0913, with a FWHM=1000km/s and a line luminosity of L_OH+_=6.92x10^8^L_{sun}_. The ratio of the observed H_2_O line luminosity over the IR luminosity, for both Hot DOGs, is consistent with previously observed star forming galaxies and AGN. The H_2_O/CO line ratio of both Hot DOGs and the OH+/H_2_O line ratio of W0410-0913 are comparable to those of luminous AGN in the literature. The bright H_2_O(2_02_-1_11_), and H_2_O(3_12_-3_03_) emission lines are likely due to the combined high star formation levels and luminous AGN in these sources. The presence of OH+ in emission, and the agreement of the observed line ratios of the Hot DOGs with luminous AGN in the literature, would suggest that the AGN emission is dominating the radiative output of these galaxies. However, followup multi-transition observations are needed to better constrain the properties of these systems.
- ID:
- ivo://CDS.VizieR/J/A+A/285/1
- Title:
- Spectrographic study of Kiso UV-excess galaxies
- Short Name:
- J/A+A/285/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/VII/141
- Title:
- Spectrophotometric Atlas of Galaxies
- Short Name:
- VII/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains 56 spectra: 55 galaxy spectra, and one night sky spectrum, which is included for users wishing to check for low-level spurious features in the galaxy spectra. The file "spectra.dat" contains a summary of the spectra. The user should consult the paper for details of the observations and a discussion of the limitations of the spectrophotometry. The spectra are integrated measurements made with apertures comparable to the diameters of the galaxies. The original spectra have been combined, rebinned to a common wavelength scale, and normalized in flux to unity at a reference wavelength of 555nm. An atmospheric extinction correction has been applied to the data, but otherwise they are not corrected for reddening, redshift, etc. The spectral range covered is 365-710 nm and the resolution is 5-8{AA}. Each spectrum consists in 1726 normalized flux values spaced each 2{AA}, stored as a file in the subdirectory "sp". Tests show that the spectrophotometry is accurate to the few percent level over small wavelength regions, and at the 10% level over the entire wavelength range. Although the data are useful for a variety of applications, the user should be forewarned that they may not be suitable for applications requiring precision colors over a long wavelength baseline (e.g., computation of K-corrections, some spectral synthesis applications).
- ID:
- ivo://CDS.VizieR/J/A+A/366/68
- Title:
- Spectrophotometric indices from galaxy bulges
- Short Name:
- J/A+A/366/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured Mg_2_, Fe5270 and Fe5335 spectrophotometric indices (LICK system) in the bulge of 89 galaxies, mostly spirals from the Heraudeau sample. The indices are reduced to a null velocity dispersion and normalized to an aperture of 0.2h^-1^kpc. The mean errors are 0.009 mag on Mg_2_, and 0.3{AA} on the iron indices. These measurements almost double the amount of similar data already available on spiral galaxies. Our data confirm the existence of the relation between Mg_2_ and sigma_0_, the central stellar velocity dispersion; and we find an even tighter relation between Mg_2_ and Vmaxrot, the maximum rotational velocity of the galaxy, deduced from HI observations. For the most massive bulges these correlations may be interpreted as a mass-metallicity relation. However, the presence of young stellar populations, traced by the detection of [OIII]{lambda}500.7nm emission, provides a clear evidence that age effects play a role. Since the contribution of the young population is anti-correlated with the mass of the galaxy, it continues the Mg_2_ vs. sigma_0_ relation toward the low sigma_0_ and globally increases its slope. We present also evidence for a new positive correlation between Fe indices and sigma_0_ and for a significant correlation between the line strength indices and the total or disk luminosity. We propose to model the whole sequence of bulges within the following framework: Bulges are composed of a primary population formed prior to the disk during the initial collapse and a secondary population formed along the evolution. The whole family of bulges can be classified in three classes: (A) The bulges dominated by a young population are generally small, have ionized gas, low velocity dispersion and low line strengths. (B) The bulges dominated by the primary population lie along the mass metallicity sequence defined for elliptical galaxies. (C) The bulges where the secondary population is significant are less Mg-overabundant than B-type bulges and deviate from the Mg_2_ vs. sigma_0_ relation of elliptical galaxies. The original data are available in Hypercat: http://www-obs.univ-lyon1.fr/hypercat The tables of measurements and the extracted 1D spectra are also available in the present archive set.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/839
- Title:
- Spectrophotometric redshifts for 1308 HUDF galaxies
- Short Name:
- J/ApJ/668/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of spectrophotometric redshifts for 1308 galaxies from the Grism ACS Program for Extragalactic Science (GRAPES) observations with the Hubble Space Telescope. These low-resolution spectra between 6000{AA} and 9500{AA} are supplemented with U, J, H, and Ks data from various facilities, resulting in redshifts computed with ~40 spectral bins per galaxy. For 75 galaxies in the range 0.5<z<1.5 with spectroscopic redshifts, the standard deviation in the fractional error in 1+z is 0.037. With this catalog, we compute the B-band luminosity function in this redshift range from 72 galaxies. Due to the depth of the GRAPES survey, we are able to accurately constrain the faint-end slope by going to MB~-18mag at z=1.0+/-0.2, nearly 2mag fainter than previous studies. The faint-end slope is alpha=-1.32+/-0.07. When compared to numerous published values at various redshifts, we find strong evidence for a steepening of the faint-end slope with redshift, which is expected in the hierarchical formation scenario of galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/157
- Title:
- Spectrophotometric redshifts of GOODS galaxies
- Short Name:
- J/ApJ/883/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the accuracy of 4000{AA}/Balmer-break based redshifts by combining Hubble Space Telescope (HST) grism data with photometry. The grism spectra are from the Probing Evolution And Reionization Spectroscopically survey with HST using the G800L grism on the Advanced Camera for Surveys. The photometric data come from a compilation by the 3D-HST collaboration of imaging from multiple surveys (notably, the Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS) and 3D-HST). We show evidence that spectrophotometric redshifts (SPZs) typically improve the accuracy of photometric redshifts by ~17%-60%. Our SPZ method is a template-fitting-based routine that accounts for correlated data between neighboring points within grism spectra via the covariance matrix formalism and also accounts for galaxy morphology along the dispersion direction. We show that the robustness of the SPZ is directly related to the fidelity of the D4000 measurement. We also estimate the accuracy of continuum-based redshifts, i.e., for galaxies that do not contain strong emission lines, based on the grism data alone ({sigma}_{Delta}z/(1+z)_^NMAD^<~0.06). Given that future space-based observatories like Wide Field InfraRed Survey Telescope and Euclid will spend a significant fraction of time on slitless spectroscopic observations, we estimate number densities for objects with |{Delta}z/(1+z_s_)|<=0.02. We predict ~700-4400 galaxies degree^-2^ for galaxies with D4000>1.1 and |{Delta}z/(1+z_s_)|<=0.02 to a limiting depth of i_AB_=24mag. This is especially important in the absence of an accompanying rich photometric data set like the existing one for the CANDELS fields, where redshift accuracy from future surveys will rely only on the presence of a feature like the 4000{AA}/Balmer breaks or the presence of emission lines within the grism spectra.
- ID:
- ivo://CDS.VizieR/J/ApJ/656/168
- Title:
- Spectrophotometry in NGC 5253
- Short Name:
- J/ApJ/656/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present echelle spectrophotometry of the blue compact dwarf galaxy NGC 5253 obtained with the VLT UVES. We have measured the intensities of a large number of permitted and forbidden emission lines in four zones of the central part of the galaxy. We detect faint CII and OII recombination lines, the first time that these are unambiguously detected in a dwarf starburst galaxy. The physical conditions of the ionized gas have been derived using a large number of different line intensity ratios.
