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2301. Mid-IR galaxy morphology from S^4^G
ID:
ivo://CDS.VizieR/J/ApJS/190/147
Title:
Mid-IR galaxy morphology from S^4^G
Short Name:
J/ApJS/190/147
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spitzer Space Telescope Infrared Array Camera imaging provides an opportunity to study all known morphological types of galaxies in the mid-IR at a depth significantly better than ground-based near-infrared and optical images. The goal of this study is to examine the imprint of the de Vaucouleurs classification volume in the 3.6um band, which is the best Spitzer waveband for galactic stellar mass morphology owing to its depth and its reddening-free sensitivity mainly to older stars. For this purpose, we have prepared classification images for 207 galaxies from the Spitzer archive, most of which are formally part of the Spitzer Survey of Stellar Structure in Galaxies (S^4^G), a Spitzer post-cryogenic ("warm") mission Exploration Science Legacy Program survey of 2331 galaxies closer than 40Mpc. For the purposes of morphology, the galaxies are interpreted as if the images are blue light, the historical waveband for classical galaxy classification studies. We find that 3.6um classifications are well correlated with blue-light classifications, to the point where the essential features of many galaxies look very similar in the two very different wavelength regimes. We present an atlas of all of the 207 galaxies analyzed here and bring attention to special features or galaxy types, such as nuclear rings, pseudobulges, flocculent spiral galaxies, I0 galaxies, double-stage and double-variety galaxies, and outer rings, that are particularly distinctive in the mid-IR.
2302. Mid-IR indicators of SF and AGN in galaxies
ID:
ivo://CDS.VizieR/J/ApJ/719/1191
Title:
Mid-IR indicators of SF and AGN in galaxies
Short Name:
J/ApJ/719/1191
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the use of mid-infrared (MIR) polycyclic aromatic hydrocarbon (PAH) bands, the continuum, and emission lines as probes of star formation (SF) and active galactic nucleus (AGN) activity in a sample of 100 "normal" and local (z~0.1) emission-line galaxies. The MIR spectra were obtained with the Spitzer Space Telescope Infrared Spectrograph as part of the Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS), which includes multi-wavelength photometry from the ultraviolet to the far-infrared and optical spectroscopy. The continuum and features were extracted using PAHFIT, a decomposition code which we find to yield PAH equivalent widths (EWs) up to ~30 times larger than the commonly used spline methods. Despite the lack of extreme objects in our sample (such as strong AGNs, low-metallicity galaxies, or ULIRGs), we find significant variations in PAH, continuum, and emission-line properties, and systematic trends between these MIR properties and optically derived physical properties, such as age, metallicity, and radiation field hardness. We revisit the diagnostic diagram relating PAH EWs and [NeII]12.8um/[OIV]25.9um line ratios and find it to be in much better agreement with the standard optical SF/AGN classification than when spline decompositions are used, while also potentially revealing obscured AGNs.
2303. Mid-IR observations in the extended Groth strip
ID:
ivo://CDS.VizieR/J/ApJ/642/126
Title:
Mid-IR observations in the extended Groth strip
Short Name:
J/ApJ/642/126
Date:
21 Oct 2021
Publisher:
CDS
Description:
A sample of about 150 AGNs was selected from observations of Chandra and XMM X-ray observatories in a 300arcmin^2^ region of the extended Groth strip (EGS), and observed by the IRAC and MIPS instruments of the Spitzer IR telescope. About 68-80% of these sources were detected by Spitzer, and they show a wide range of mid-infrared properties. The IRAC SED type does not directly correspond to X-ray spectral type (hard/soft). The mid-IR properties of X-ray-detected Lyman break, radio, submillimeter, and optically faint sources vary widely, and for the most part are not distinct from those of the general X-ray/IR source population. X-ray sources emit 6-11% of the integrated mid-IR light, making them significant contributors to the cosmic infrared background.
2304. Mid-IR properties of GOALS nearby LIRGs
ID:
ivo://CDS.VizieR/J/ApJS/206/1
Title:
Mid-IR properties of GOALS nearby LIRGs
Short Name:
J/ApJS/206/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Great Observatories All-Sky LIRG Survey (GOALS, Armus et al. 2009PASP..121..559A) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here we present low resolution Spitzer Infrared Spectrograph spectra covering 5-38um and provide a basic analysis of the mid-IR spectral properties observed for nearby LIRGs. In a companion paper, we discuss detailed fits to the spectra and compare the LIRGs to other classes of galaxies. The GOALS sample of 244 nuclei in 180 luminous (10^11^<=L_IR_/L_{sun}_<10^12^) and 22 ultraluminous (L_IR_/L_{sun}_>=10^12^) IR galaxies represents a complete subset of the IRAS Revised Bright Galaxy Sample (Sanders, 2003, Cat. J/AJ/126/1607) and covers a range of merger stages, morphologies, and spectral types. The majority (>60%) of the GOALS LIRGs have high 6.2um polycyclic aromatic hydrocarbon (PAH) equivalent widths (EQW_6.2um_>0.4um) and low levels of silicate absorption (s_9.7um_>-1.0).
2305. Mid-IR properties of OH maser galaxies
ID:
ivo://CDS.VizieR/J/A+A/570/A110
Title:
Mid-IR properties of OH maser galaxies
Short Name:
J/A+A/570/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., L_OH_>10L_{sun}_) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22{mu}m (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ~40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1-W2>=0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4{mu}m and 4.6{mu}m) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4{mu}m and 4.6{mu}m luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F_22{mu}m_/F_3.4{mu}m_). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index {alpha}_22-12_ than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22{mu}m and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support the pumping of OHM emission that is dominated by the far infrared radiation, instead of the MIR radiation.
2306. Mid-IR/radio correlation for Ghat galaxies
ID:
ivo://CDS.VizieR/J/A+A/581/L5
Title:
Mid-IR/radio correlation for Ghat galaxies
Short Name:
J/A+A/581/L5
Date:
21 Oct 2021
Publisher:
CDS
Description:
Wright et al. (2014ApJ...792...26W) have embarked on a search for advanced Karadashev Type III civilisations via the compilation of a sample of sources with extreme mid-IR emission and colours. The aim is to furnish a list of candidate galaxies that might harbour an advanced Kardashev Type III civilisation; in this scenario, the mid-IR emission is then primarily associated with waste heat energy by-products. I apply the mid-IR radio correlation to this Glimpsing Heat from Alien Technology (Ghat) sample, a catalogue of 93 candidate galaxies compiled by Griffith et al., 2015ApJS..217...25G. I demonstrate that the mid-IR and radio luminosities are correlated for the sample, determining a k-corrected value of q_22_=1.35+/-0.42 . By comparison, a similar measurement for 124 galaxies drawn from the First Look Survey (FLS) has q_22_=0.87+/-0.27. The statistically significant difference of the mean value of q_22_ for these two samples, taken together with their more comparable far-IR properties, suggests that the Ghat sample shows excessive emission in the mid-IR. The fact that the Ghat sample largely follows the mid-IR radio correlation strongly suggests that the vast majority of these sources are associated with galaxies in which natural astrophysical processes are dominant. This simple application of the mid-IR radio correlation can substantially reduce the number of false positives in the Ghat catalogue since galaxies occupied by advanced Kardashev Type III civilisations would be expected to exhibit very high values of q. I identify nine outliers in the sample with q_22_>2 of which at least three have properties that are relatively well explained via standard astrophysical interpretations e.g. dust emission associated with nascent star formation and/or nuclear activity from a heavily obscured AGN. The other outliers have not been studied in any great detail, and are deserving of further observation. I also note that the comparison of resolved mid-IR and radio images of galaxies on sub-galactic (kpc) scales can also be useful in identifying and recognising artificial mid-IR emission from less advanced intermediate Type II/III civilisations. Nevertheless, from the bulk properties of the Ghat sample, I conclude that Kardashev Type III civilisations are either very rare or do not exist in the local Universe.
2307. Mid-IR spectrum of star-forming galaxies
ID:
ivo://CDS.VizieR/J/ApJ/656/770
Title:
Mid-IR spectrum of star-forming galaxies
Short Name:
J/ApJ/656/770
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of low-resolution 5-38um Spitzer IRS spectra of the inner few square kiloparsecs of 59 nearby galaxies spanning a large range of star formation properties. A robust method for decomposing mid-infrared galaxy spectra is described and used to explore the behavior of PAH emission and the prevalence of silicate dust extinction.
2308. Mid-IR Tully-Fisher relation with WISE & 2MTF
ID:
ivo://CDS.VizieR/J/ApJ/771/88
Title:
Mid-IR Tully-Fisher relation with WISE & 2MTF
Short Name:
J/ApJ/771/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4{mu}m W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) galaxy catalog, spanning a range of environments including field, group, and cluster galaxies. This constitutes the largest mid-infrared TF relation constructed to date. After applying a number of corrections to galaxy magnitudes and line widths, we measure a master TF relation given by M_corr_=-22.24-10.05[log(W_corr_)-2.5], with an average dispersion of {sigma}_WISE_=0.686mag. There is some tension between WISE TF and a preliminary 3.6{mu}m relation, which has a shallower slope and almost no intrinsic dispersion. However, our results agree well with a more recent relation constructed from a large sample of cluster galaxies. We additionally compare WISE TF to the near-infrared 2MTF template relations, finding a good agreement between the TF parameters and total dispersions of WISE TF and the 2MTF K-band template. This fact, coupled with typical galaxy colors of (K-W1)~0, suggests that these two bands are tracing similar stellar populations, including the older, centrally-located stars in the galactic bulge which can (for galaxies with a prominent bulge) dominate the light profile.
2309. MILES base models & new line index system
ID:
ivo://CDS.VizieR/J/MNRAS/404/1639
Title:
MILES base models & new line index system
Short Name:
J/MNRAS/404/1639
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical spectral range at moderately high resolution [full width at half-maximum (FWHM)=2.3{AA}]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical stellar spectral library [Medium resolution INT Library of Empirical Spectra (MILES)], which follows the chemical evolution pattern of the solar neighbourhood. The models rely as much as possible on empirical ingredients, not just on the stellar spectra, but also on extensive photometric libraries, which are used to determine the transformations from the theoretical parameters of the isochrones to observational quantities. The unprecedented stellar parameter coverage of the MILES stellar library allowed us to safely extend our optical SSP SED predictions from intermediate- to very-old-age regimes and the metallicity coverage of the SSPs from super-solar to [M/H]=-2.3. SSPs with such low metallicities are particularly useful for globular cluster studies. We have computed SSP SEDs for a suite of initial mass function shapes and slopes. We provide a quantitative analysis of the dependence of the synthesized SSP SEDs on the (in)complete coverage of the stellar parameter space in the input library that not only shows that our models are of higher quality than those of other works, but also in which range of SSP parameters our models are reliable.
2310. Milky Way mass model and rotation curve
ID:
ivo://CDS.VizieR/J/ApJ/885/87
Title:
Milky Way mass model and rotation curve
Short Name:
J/ApJ/885/87
Date:
15 Mar 2022 08:00:47
Publisher:
CDS
Description:
We discuss a model for the Milky Way obtained by fitting the observed terminal velocities with the radial acceleration relation. The resulting stellar surface density profile departs from a smooth exponential disk, having bumps and wiggles that correspond to massive spiral arms. These features are used to estimate the term for the logarithmic density gradient in the Jeans equation, which turn out to have exactly the right location and amplitude to reconcile the apparent discrepancy between the stellar rotation curve and that of the interstellar gas. This model also predicts a gradually declining rotation curve outside the solar circle with slope -1.7km/s/kpc, as subsequently observed.

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