A Near-Infrared Spectroscopic Survey of K-selected Galaxies at z ~ 2.3: Comparison of Stellar Population Synthesis Codes and Constraints from the Rest-frame NIR
Adam Muzzin, Danilo Marchesini, Pieter G. van Dokkum, Ivo Labbé, Mariska Kriek, Marijn Franx
We present SED modeling of a sample of 34 K-selected galaxies at z ~ 2.3. These galaxies have NIR spectroscopy that samples the rest-frame Balmer/4000A break as well as deep photometry in thirteen broadband filters. New to our analysis is IRAC data that extend the SEDs into the rest-frame NIR. Comparing parameters determined from SED fits with and without the IRAC data we find that the IRAC photometry significantly improves the confidence intervals of Tau, A_v, stellar mass, and SFR for individual galaxies, but does not systematically alter the mean parameters of the sample. We use the IRAC data to assess how well current stellar population synthesis codes describe the rest-frame NIR SEDs of young galaxies where discrepancies between treatments of the TP-AGB phase of stellar evolution are most pronounced. The models of Bruzual & Charlot (2003), Maraston (2005), and Charlot & Bruzual (2008) all successfully reproduce the SEDs of our galaxies with < 5% differences in the quality of fit; however, the best-fit masses from each code differ systematically by as much as a factor of 1.5, and other parameters vary more, up to factors of 2-3. A comparison of best-fit stellar population parameters from different SPS codes, dust laws, and metallicities shows that the choice of SPS code is the largest systematic uncertainty in most parameters, and that systematic uncertainties are typically larger than the formal random uncertainties. The SED fitting confirms our previous result that galaxies with strongly suppressed star formation account for ~ 50% of the K-bright population at z ~ 2.3; however, the uncertainty in this fraction is large due to systematic differences in the SSFRs derived from the three SPS models.
Chronos is our response to ESA's call for white papers to define the science for the future L2, L3 missions. Chronos targets the formation and evolution of galaxies, by collecting the deepest NIR spectroscopic data, from the formation of the first galaxies at z~10 to the peak of formation activity at z~1-3. The strong emission from the atmospheric background makes this type of survey impossible from a ground-based observatory. The spectra of galaxies represent the equivalent of a DNA fingerprint, containing information about the past history of star formation and chemical enrichment. The propo…
We report the multi-wavelength identification of the X-ray sources found in the Subaru-XMM-Newton Deep Survey (SXDS) using deep imaging data covering the wavelength range between the far-UV to the mid-IR. We select a primary counterpart of each X-ray source by applying the likelihood ratio method to R-band, 3.6micron, near-UV, and 24micron source catalogs as well as matching catalogs of AGN candidates selected in 1.4GHz radio and i'-band variability surveys. Once candidates of Galactic stars, ultra-luminous X-ray sources in a nearby galaxy, and clusters of galaxies are removed there are 896 AG…
Dwarf galaxies provide insights on the processes of star formation and chemical enrichment at the low end of the galaxy mass function, as well as on the clustering of dark matter on small scales. In studies of Local Group dwarf galaxies, spectroscopic samples of individual stars are used to derive the internal kinematics and abundance properties of these galaxies. It is therefore important to clean these samples from Milky Way stars, not related to the dwarf galaxy, since they can contaminate the analysis of the properties of these objects. Here we introduce a new diagnostic for separating Mil…
We present near infrared (NIR) IRTF/SpeX spectra of the intermediate-age galaxy M32 and the post-starburst galaxy NGC 5102. We show that features from thermally-pulsing asymptotic giant branch (TP-AGB) and main sequence turn-off (MSTO) stars yield similar ages to those derived from optical spectra. The TP-AGB can dominate the NIR flux of a coeval stellar population between ~0.1 and ~2 Gyr, and the strong features of (especially C-rich) TP-AGB stars are useful chronometers in integrated light studies. Likewise, the Paschen series in MSTO stars is stongly dependent on age and is an indicator of …
We present the spectroscopic confirmation of a galaxy cluster at $z=2.095$ in the COSMOS field. This galaxy cluster was first reported in the ZFOURGE survey as harboring evolved massive galaxies using photometric redshifts derived with deep near-infrared (NIR) medium-band filters. We obtain medium resolution ($R \sim$ 3600) NIR spectroscopy with MOSFIRE on the Keck 1 telescope and secure 180 redshifts in a $12'\times12'$ region. We find a prominent spike of 57 galaxies at $z=2.095$ corresponding to the galaxy cluster. The cluster velocity dispersion is measured to be $σ_{\rm v1D}$ = 552 $\pm$ …
Recently, the Nancy Grace Roman Space Telescope (Roman) Project raised the possibility of adding another filter to Roman. Based on the Filter Working Group's recommendations, this filter may be a K-band filter, extending significantly redder than the current-reddest F184. Among other scientific possibilities, this K filter raises the possibility of measuring SNe Ia in the rest-frame NIR out to higher redshifts than is possible with the current filter complement. I perform a simple survey optimization for NIR SN Ia distances with Roman, simultaneously optimizing both filter cutoffs and survey s…
Mennickent et al.and Sabogal et al.identified a large number of Classical Be (CBe) candidates in the L&SMC based on their photometric variability using the OGLEII database. They classified these stars into four different groups based on the appearance of their variability. We studied the infrared properties of the sample as well as the spectroscopic properties of a subsample. We cross-correlated the optical sample with the IRSF catalog to obtain the J, H, Ks magnitudes of all the four types of stars in the L&SMC. Spectra of 120 stars belonging to the types 1, 2 and 3 were analysed to study the…
We explore the feasibility and limitations of using the 1.6um bump as a photometric redshift indicator and selection technique and use it to study the rest-frame H-band galaxy luminosity and stellar mass functions at redshift z~2. We use publicly available Spitzer/IRAC images in the GOODS fields and find that color selection in the IRAC bandpasses alone is comparable in completeness and contamination to BzK selection. We find that the shape of the 1.6um bump is robust, and photometric redshifts are not greatly affected by choice of model parameters. Comparison with spectroscopic redshifts show…
We characterize the ability of the ALHAMBRA survey to assign accurate photo-z's to BLAGN and QSOs based on their ALHAMBRA very-low-resolution optical-NIR spectroscopy. A sample of 170 spectroscopically identified BLAGN and QSOs have been used together with a library of templates (including SEDs from AGN, normal, starburst galaxies and stars) in order to fit the 23 photometric data points provided by ALHAMBRA in the optical and NIR (20 medium-band optical filters plus the standard JHKs). We find that the ALHAMBRA photometry is able to provide an accurate photo-z and spectral classification for …
The SPHEREx Instrument: Calibration, testing and performance measurements of the NIR spectroscopic surveyor from the laboratory to in-orbit commissioning
California Institute of Technology（加州理工学院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Rochester Institute of Technology（罗切斯特理工学院）
We present the AKARI near-infrared (NIR; 2.5-5 micron) spectroscopic study of 36 (ultra)luminous infrared galaxies [(U)LIRGs] at z=0.01-0.4. We measure the NIR spectral features including the strengths of 3.3 micron polycyclic aromatic hydrocarbon (PAH) emission and hydrogen recombination lines (Brα. and Brβ), optical depths at 3.1 and 3.4 micron, and NIR continuum slope. These spectral features are used to identify optically elusive, buried AGN. We find that half of the (U)LIRGs optically classified as non-Seyferts show AGN signatures in their NIR spectra. Using a combined sample of (U)LIRGs …
We present near-infrared (NIR) spectroscopic observations of the blue compact dwarf (BCD) galaxy Mrk 59, obtained with the TripleSpec spectrograph mounted on the 3.5m APO telescope. The NIR spectrum of Mrk 59, which covers the 0.90 - 2.40 micron wavelength range, shows atomic hydrogen, molecular hydrogen, helium, sulfur and iron emission lines. The NIR data have been supplemented by a SDSS optical spectrum. We found extinction in the BCD to be low [A(V)=0.24 mag] and to be the same in both the optical and NIR ranges. The NIR light does not reveal hidden star formation. The H2 emission comes fr…
We investigate rest-frame near-infrared (NIR) morphologies of a sample of 139 galaxies with M_{s} >= 1 x 10^{10} M_{sun} at z=0.8-1.2 in the GOODS-North field using our deep NIR imaging data (MOIRCS Deep Survey, MODS). We focus on Luminous Infrared Galaxies (LIRGs), which dominate high star formation rate (SFR) density at z~1, in the sample identified by cross-correlating with the Spitzer/MIPS 24um source catalog. We perform two-dimensional light profile fitting of the z~1 galaxies in the Ks-band (rest-frame J-band) with a single component Sersic model. We find that at z~1, ~90% of LIRGs have …
We present 13 Type Ia supernovae (SNe Ia) observed in the restframe near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared Camera (WHIRC) on the WIYN 3.5-m telescope. With only 1-3 points per light curve and a prior on the time of maximum from the spectrum used to type the object we measure an H-band dispersion of spectroscopically normal SNe Ia of 0.164 mag. These observations continue to demonstrate the improved standard brightness of SNe Ia in H-band even with limited data. Our sample includes two SNe Ia at z ~ 0.09, which represent the most distant restframe NIR H-…
HIZOA J0836-43is one of the most HI-massive galaxies in the local (z<0.1) Universe. Not only are such galaxies extremely rare, but this "coelacanth" galaxy exhibits characteristics -- in particular its active, inside-out stellar disk-building -- that appear more typical of past (z ~ 1) star formation, when large gas fractions were more common. Unlike most local giant HI galaxies, it is actively star forming. Moreover, the strong infrared emission is not induced by a merger event or AGN, as is commonly found in other local LIRGs. The galaxy is suggestive of a scaled-up version of local spiral g…
We study how the spectral fitting of galaxies, in terms of light fractions derived in one spectral region translates into another region, by using results from evolutionary synthesis models. In particular, we examine propagation dependencies on Evolutionary Population Synthesis (EPS, {\sc grasil}, {\sc galev}, Maraston and {\sc galaxev}) models, age, metallicity, and stellar evolution tracks over the near-UV---near infrared (NUV---NIR, 3500Å to 2.5\mc) spectral region. Our main results are: as expected, young ($t \lesssim$ 400 Myr) stellar population fractions derived in the optical cannot be …
We present sensitive near--infrared VLT ISAAC spectroscopic observations of the z=6.08 quasar SDSS J030331.40-001912.9. This QSO is more than a magnitude fainter than other QSOs at z~6 for which NIR spectroscopy has been obtained to date and is therefore presumably more representative of the QSO population at the end of Cosmic Reionization. Combining rest--frame UV continuum luminosity with the width measurements of the Mg II and C IV lines, we derive a black hole mass of 2(+1.0/-0.5) x 10^8 solar masses, the lowest mass observed for z~6 QSOs to date, and derive an Eddington ratio of 1.6(+0.4/…
Astronomical observations toward Sagittarius B2(M) as well as other sources with APEX have recently suggested that the rest frequency of the J = 1 - 0 transitions of 13CH+ is too low by about 80 MHz. Improved rest frequencies of isotopologs of methylidynium should be derived to support analyses of spectral recording obtained with the ongoing Herschel mission or the upcoming SOFIA. Laboratory electronic spectra of four isotopologs of CH+ have been subjected to one global least-squares fit. Laboratory data for the J = 1 - 0 ground state rotational transitions of CH+, 13CH+, and CD+, which became…
We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR C I lines, and the C I λ1.0693 μm line is the strongest ever observed in a SN Ia. Interestingly, no strong optical C II counterparts were found, even though the optical spe…
While conventional Type Ia supernova (SN Ia) cosmology analyses rely primarily on rest-frame optical light curves to determine distances, SNe Ia are excellent standard candles in near-infrared (NIR) light, which is significantly less sensitive to dust extinction. A SN Ia spectral energy distribution (SED) model capable of fitting rest-frame NIR observations is necessary to fully leverage current and future SN Ia datasets from ground- and space-based telescopes including HST, LSST, JWST, and RST. We construct a hierarchical Bayesian model for SN Ia SEDs, continuous over time and wavelength, fro…
