- ID:
- ivo://CDS.VizieR/J/A+A/609/A116
- Title:
- Low extinction TGAS HR Catalogue
- Short Name:
- J/A+A/609/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gaia Data Release 1 allows the recalibration of standard candles such as the red clump stars. To use those stars, they first need to be accurately characterised. In particular, colours are needed to derive interstellar extinction. As no filter is available for the first Gaia data release and to avoid the atmosphere model mismatch, an empirical calibration is unavoidable. The purpose of this work is to provide the first complete and robust photometric empirical calibration of the Gaia red clump stars of the solar neighbourhood through colour-colour, effective temperature-colour, and absolute magnitude-colour relations from the Gaia, Johnson, 2MASS, Hipparcos, Tycho-2, APASS-SLOAN, and WISE photometric systems, and the APOGEE DR13 spectroscopic temperatures. We used a 3D extinction map to select low reddening red giants. To calibrate the colour-colour and the effective temperature-colour relations, we developed a MCMC method that accounts for all variable uncertainties and selects the best model for each photometric relation. We estimated the red clump absolute magnitude through the mode of a kernel-based distribution function. We provide 20 colour versus G-Ks relations and the first Teff versus G-Ks calibration. We obtained the red clump absolute magnitudes for 15 photometric bands with, in particular, M_Ks_=(-1.606+/-0.009) and M_G_=(0.495+/-0.009)+(1.121+/-0.128)(G-Ks-2.1). We present a dereddened Gaia-TGAS HR diagram and use the calibrations to compare its red clump and its red giant branch bump with Padova isochrones.
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- ID:
- ivo://CDS.VizieR/J/ApJ/857/104
- Title:
- Low surface brightness galaxies from HSC-SSP
- Short Name:
- J/ApJ/857/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of extended low surface brightness galaxies (LSBGs) identified in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Using the first ~200deg^2^ of the survey, we have uncovered 781 LSBGs, spanning red (g-i>=0.64) and blue (g-i<0.64) colors and a wide range of morphologies. Since we focus on extended galaxies (r_eff_=2.5"-14"), our sample is likely dominated by low-redshift objects. We define LSBGs to have mean surface brightnesses \bar{mu}_eff_(g)>24.3mag/arcsec^2^, which allows nucleated galaxies into our sample. As a result, the central surface brightness distribution spans a wide range of {mu}_0_(g)=18-27.4mag/arcsec^2^, with 50% and 95% of galaxies fainter than 24.3 and 22mag/arcsec^2^, respectively. Furthermore, the surface brightness distribution is a strong function of color, with the red distribution being much broader and generally fainter than that of the blue LSBGs, and this trend shows a clear correlation with galaxy morphology. Red LSBGs typically have smooth light profiles that are well characterized by single-component Sersic functions. In contrast, blue LSBGs tend to have irregular morphologies and show evidence for ongoing star formation. We cross-match our sample with existing optical, HI, and ultraviolet catalogs to gain insight into the physical nature of the LSBGs. We find that our sample is diverse, ranging from dwarf spheroidals and ultradiffuse galaxies in nearby groups to gas-rich irregulars to giant LSB spirals, demonstrating the potential of the HSC-SSP to provide a truly unprecedented view of the LSBG population.
- ID:
- ivo://CDS.VizieR/J/AJ/145/94
- Title:
- Luminosities of protostars from two Spitzer surveys
- Short Name:
- J/AJ/145/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Motivated by the long-standing "luminosity problem" in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate L_bol_ for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01L_{sun}_ to 69L_{sun}_, and has a mean and median of 4.3L_{sun}_ and 1.3L_{sun}_, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L_bol_<~0.5L_{sun}_) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70{mu}m<{lambda}<850{mu}m) and have L_bol_ underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.
- ID:
- ivo://CDS.VizieR/J/AJ/157/22
- Title:
- Luminous and variable stars in NGC 2403 and M81
- Short Name:
- J/AJ/157/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of spectroscopy and multi-wavelength photometry of luminous and variable star candidates in the nearby spiral galaxies NGC 2403 and M81. We discuss specific classes of stars, the Luminous Blue Variables (LBVs), B[e] supergiants (sgB[e]), and the high-luminosity yellow hypergiants. We identify two new LBV candidates, and three sgB[e] stars in M81. We also find that some stars that were previously considered LBV candidates are actually field stars. The confirmed and candidate LBVs and sgB[e] stars together with the other confirmed members are shown on the HR Diagrams for their respective galaxies. We also present the HR Diagrams for the two "SN impostors", V37 (SN2002kg) and V12 (SN1954J) in NGC 2403 and the stars in their immediate environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/37
- Title:
- Luminous WISE-selected quasars in SDSS Stripe 82
- Short Name:
- J/ApJ/861/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopically complete sample of 147 infrared-color-selected active galactic nuclei (AGNs) down to a 22{mu}m flux limit of 20mJy over the ~270deg^2^ of the Sloan Digital Sky Survey Stripe 82 region. Most of these sources are in the QSO luminosity regime (Lbol>~10^12^L_{sun}_) and are found out to z~3. We classify the AGNs into three types, finding 57 blue, unobscured Type-1 (broad-lined) sources; 69 obscured, Type-2 (narrow-lined) sources; and 21 moderately reddened Type-1 sources (broad-lined and E(B-V)>0.25). We study a subset of this sample in X-rays and analyze their obscuration to find that our spectroscopic classifications are in broad agreement with low, moderate, and large amounts of absorption for Type-1, red Type-1, and Type-2 AGNs, respectively. We also investigate how their X-ray luminosities correlate with other known bolometric luminosity indicators such as [OIII] line luminosity (L[OIII]) and infrared luminosity (L6{mu}m). While the X-ray correlation with L[OIII] is consistent with previous findings, the most infrared-luminous sources appear to deviate from established relations such that they are either underluminous in X-rays or overluminous in the infrared. Finally, we examine the luminosity function evolution of our sample, and by AGN type, in combination with the complementary, infrared-selected, AGN sample of Lacy et al. (2013), spanning over two orders of magnitude in luminosity. We find that the two obscured populations evolve differently, with reddened Type-1 AGNs dominating the obscured AGN fraction (~30%) for L_5{mu}m_>10^45^erg/s, while the fraction of Type-2 AGNs with L_5{mu}m_<10^45^erg/s rises sharply from 40% to 80% of the overall AGN population.
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/899
- Title:
- LVL SEDs and physical properties
- Short Name:
- J/MNRAS/445/899
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the panchromatic spectral energy distributions (SEDs) of the Local Volume Legacy (LVL) survey which consists of 258 nearby galaxies (D<11Mpc). The wavelength coverage spans the ultraviolet to the infrared (1500{AA}-24{mu}m) which is utilized to derive global physical properties (i.e. star formation rate, stellar mass, internal extinction due to dust). With these data, we find colour-colour relationships and correlated trends between observed and physical properties (i.e. optical magnitudes and dust properties, optical colour and specific star formation rate, and ultraviolet-infrared colour and metallicity). The SEDs are binned by different galaxy properties to reveal how each property affects the observed shape of these SEDs. In addition, due to the volume-limited nature of LVL, we utilize the dwarf-dominated galaxy sample to test star formation relationships established with higher mass galaxy samples. We find good agreement with the star-forming `main-sequence' relationship, but find a systematic deviation in the infrared `main sequence' at low luminosities. This deviation is attributed to suppressed polycyclic aromatic hydrocarbon (PAH) formation in low-metallicity environments and/or the destruction of PAHs in more intense radiation fields occurring near a suggested threshold in star formation rates (sSFR) at a value of log(sSFR)~-10.2.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/171
- Title:
- Ly{alpha} profile in 43 Green Pea galaxies
- Short Name:
- J/ApJ/844/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied Lyman-{alpha} (Ly{alpha}) escape in a statistical sample of 43 Green Peas with HST/COS Ly{alpha} spectra. Green Peas are nearby star-forming galaxies with strong [OIII]{lambda}5007 emission lines. Our sample is four times larger than the previous sample and covers a much more complete range of Green Pea properties. We found that about two-thirds of Green Peas are strong Ly{alpha} line emitters with rest-frame Ly{alpha} equivalent width >20{AA}. The Ly{alpha} profiles of Green Peas are diverse. The Ly{alpha} escape fraction, defined as the ratio of observed Ly{alpha} flux to intrinsic Ly{alpha} flux, shows anti-correlations with a few Ly{alpha} kinematic features-both the blue peak and red peak velocities, the peak separations, and the FWHM of the red portion of the Ly{alpha} profile. Using properties measured from Sloan Digital Sky Survey optical spectra, we found many correlations-the Ly{alpha} escape fraction generally increases at lower dust reddening, lower metallicity, lower stellar mass, and higher [OIII]/[OII] ratio. We fit their Ly{alpha} profiles with the HI shell radiative transfer model and found that the Ly{alpha} escape fraction is anti-correlated with the best-fit N_HI_. Finally, we fit an empirical linear relation to predict f_esc_^Ly{alpha}^ from the dust extinction and Ly{alpha} red peak velocity. The standard deviation of this relation is about 0.3dex. This relation can be used to isolate the effect of intergalactic medium (IGM) scatterings from Ly{alpha} escape and to probe the IGM optical depth along the line of sight of each z>7 Ly{alpha} emission-line galaxy in the James Webb Space Telescope era.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/41
- Title:
- Lyman Continuum in 111 GOODS and ERS galaxies
- Short Name:
- J/ApJ/897/41
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We present our analysis of the Lyman continuum (LyC) emission and escape fraction of 111 spectroscopically verified galaxies with and without active galactic nuclei (AGN) from 2.26<z<4.3. We extended our ERS sample from Smith et al. with 64 galaxies in the GOODS North and South fields using WFC3/UVIS F225W, F275W, and F336W mosaics we independently drizzled using the HDUV, CANDELS, and UVUDF data. Among the 17 AGN from the 111 galaxies, one provided a LyC detection in F275W at m_AB_=23.19mag (signal-to-noise ratio, S/N~133) and GALEX NUV at m_AB_=23.77mag (S/N~13). We simultaneously fit SDSS and Chandra spectra of this AGN to an accretion disk and Comptonization model, and find f_esc_ values of f_esc_^F275W^~28_-4_^+20^% and f_esc_^NUV^~30_-5_^+22^% . For the remaining 110 galaxies, we stack image cutouts that capture their LyC emission using the F225W, F275W, and F336W data of the GOODS and ERS samples, and both combined, as well as subsamples of galaxies with and without AGN, and all galaxies. We find the stack of 17 AGN dominate the LyC production from <z>~2.3-4.3 by a factor of ~10 compared to all 94 galaxies without AGN. While the IGM of the early universe may have been reionized mostly by massive stars, there is evidence that a significant portion of the ionizing energy came from AGN.
- ID:
- ivo://CDS.VizieR/J/AJ/159/84
- Title:
- Machine-learning regression of extinction in Gaia DR2
- Short Name:
- J/AJ/159/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Machine learning has become a popular tool to help us make better decisions and predictions, based on experiences, observations, and analyzing patterns, within a given data set without explicit functions. In this paper, we describe an application of the supervised machine-learning algorithm to the extinction regression for the second Gaia data release, based on the combination of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, Sloan Extension for Galactic Understanding and Exploration, and the Apache Point Observatory Galactic Evolution Experiment. The derived extinction in our training sample is consistent with other spectrum-based estimates, and its standard deviation of the cross-validations is 0.0127mag. A blind test is carried out using the RAdial Velocity Experiment catalog, and the standard deviation is 0.0372mag. Such a precise training sample enables us to regress the extinction, E(BP-RP), for 133 million stars in the second Gaia data release. Of these, 106 million stars have the uncertainties less than 0.1mag, which suffer less bias from the external regression. We also find that there are high deviations between the extinctions from photometry-based methods, and between spectrum- and photometry-based methods. This implies that the spectrum-based method could bring more signal to a regressing model than multiband photometry, and a higher signal-to-noise ratio would acquire a more reliable result.
- ID:
- ivo://CDS.VizieR/J/ApJS/226/5
- Title:
- MACT survey. I. Opt. spectroscopy in Subaru Deep Field
- Short Name:
- J/ApJS/226/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep rest-frame optical spectroscopy is critical for characterizing and understanding the physical conditions and properties of the ionized gas in galaxies. Here, we present a new spectroscopic survey called "Metal Abundances across Cosmic Time" or MACT, which will obtain rest-frame optical spectra for ~3000 emission-line galaxies. This paper describes the optical spectroscopy that has been conducted with MMT/Hectospec and Keck/DEIMOS for ~1900 z=0.1-1 emission-line galaxies selected from our narrowband and intermediate-band imaging in the Subaru Deep Field. In addition, we present a sample of 164 galaxies for which we have measured the weak [OIII]{lambda}4363 line (66 with at least 3{sigma} detections and 98 with significant upper limits). This nebular emission line determines the gas-phase metallicity by measuring the electron temperature of the ionized gas. This paper presents the optical spectra, emission-line measurements, interstellar properties (e.g., metallicity, gas density), and stellar properties (e.g., star formation rates, stellar mass). Paper II of the MACT survey (Ly et al. 2016ApJ...828...67L) presents the first results on the stellar mass-gas metallicity relation at z<=1 using the sample with [OIII]{lambda}4363 measurements.
