arXiv subjects

S. Finkelstein

Publications and source records attributed to S. Finkelstein.

22 records · Page 2Linked to original sources

arXiv2014

New constraints on dust emission and UV attenuation of z=6.5-7.5 galaxies from millimeter observations

We have targeted two recently discovered Lyman break galaxies (LBGs) to search for dust continuum and [CII] 158 micron line emission. The strongly lensed z~6.8 LBG A1703-zD1 behind the galaxy cluster Abell 1703, and the spectroscopically confirmed z=7.508 LBG z8-GND-5296 in the GOODS-N field have been observed with the Plateau de Bure interferometer (PdBI) at 1.2mm. These observations have been combined with those of three z>6.5 Lya emitters (named HCM6A, Himiko, and IOK-1), for which deep measurements were recently obtained with the PdBI and ALMA. [CII] is undetected in both galaxies, providing a deep upper limit for Abell1703-zD1, comparable to recent ALMA non-detections. Dust continuum emission from Abell1703-zD1 and z8-GND-5296 is not detected with an rms of 0.12 and 0.16 mJy/beam. From these non-detections we derive upper limits on their IR luminosity and star formation rate, dust mass, and UV attenuation. Thanks to strong gravitational lensing the limit for Abell1703-zD1 is probing the sub-LIRG regime ($L_{IR} <8.1 \times 10^{10}$ Lsun) and very low dust masses ($M_d<1.6 \times 10^7$ Msun). We find that all five galaxies are compatible with the Calzetti IRX-$β$ relation, their UV attenuation is compatible with several indirect estimates from other methods (the UV slope, extrapolation of the attenuation measured from the IR/UV ratio at lower redshift, and SED fits), and the dust-to-stellar mass ratio is not incompatible with that of galaxies from z=0 to 3. For their stellar mass the high-z galaxies studied here have an attenuation below the one expected from the mean relation of low redshift (z<1.5) galaxies. More and deeper (sub)-mm data are clearly needed to directly determine the UV attenuation and dust content of the dominant population of high-z star-forming galaxies and to establish more firmly their dependence on stellar mass, redshift, and other properties.

astro-ph.GA↗

arXiv2014

Constraining the Lyman Alpha Escape Fraction with Far-Infrared Observations of Lyman Alpha Emitters

We study the far-infrared properties of 498 Lyman Alpha Emitters (LAEs) at z=2.8, 3.1 and 4.5 in the Extended Chandra Deep Field-South, using 250, 350 and 500 micron data from the Herschel Multi-tiered Extragalactic Survey (HerMES) and 870 micron data from the LABOCA ECDFS Submillimeter Survey (LESS). None of the 126, 280 or 92 LAEs at z=2.8, 3.1 and 4.5, respectively, are individually detected in the far-infrared data. We use stacking to probe the average emission to deeper flux limits, reaching $1σ$ depths of ~0.1 to 0.4 mJy. The LAEs are also undetected at $\ge3σ$ in the stacks, although a $2.5σ$ signal is observed at 870 micron for the z=2.8 sources. We consider a wide range of far-infrared spectral energy distributions (SEDs), including a M82 and an Sd galaxy template, to determine upper limits on the far-infrared luminosities and far-infrared-derived star-formation rates of the LAEs. These star-formation rates are then combined with those inferred from the Ly$α$ and UV emission to determine lower limits on the LAEs Ly$α$ escape fraction ($f_{\rm esc}($Ly$α$)). For the Sd SED template, the inferred LAEs $f_{\rm esc}($Ly$α$) are $\gtrsim30%$ ($1σ$) at z=2.8, 3.1 and 4.5, which are all significantly higher than the global $f_{\rm esc}($Ly$α$) at these redshifts. Thus, if the LAEs $f_{\rm esc}($Ly$α$) follows the global evolution then they have warmer far-infrared SEDs than the Sd galaxy template. The average and M82 SEDs produce lower limits on the LAE $f_{\rm esc}($Ly$α$) of ~10 to 20% ($1σ$), all of which are slightly higher than the global evolution of $f_{\rm esc}($Ly$α$) but consistent with it at the 2 to 3$σ$ level.

astro-ph.CO↗

arXiv2014

The Herschel Stripe 82 Survey (HerS): Maps and Early Catalog

We present the first set of maps and band-merged catalog from the Herschel Stripe 82 Survey (HerS). Observations at 250, 350, and 500 micron were taken with the Spectral and Photometric Imaging Receiver (SPIRE) instrument aboard the Herschel Space Observatory. HerS covers 79 deg$^2$ along the SDSS Stripe 82 to a depth of 13.0, 12.9, and 14.8 mJy beam$^{-1}$ (including confusion) at 250, 350, and 500 micron, respectively. HerS was designed to measure correlations with external tracers of the dark matter density field --- either point-like (i.e., galaxies selected from radio to X-ray) or extended (i.e., clusters and gravitational lensing) --- in order to measure the bias and redshift distribution of intensities of infrared-emitting dusty star-forming galaxies and AGN. By locating HeRS in Stripe 82, we maximize the overlap with available and upcoming cosmological surveys. The band-merged catalog contains 3.3x10$^4$ sources detected at a significance of >3 $σ$ (including confusion noise). The maps and catalog are available at http://www.astro.caltech.edu/hers/

astro-ph.CO↗

arXiv2011

A Link to the Past: Using Markov Chain Monte Carlo Fitting to Constrain Fundamental Parameters of High-Redshift Galaxies

We have a developed a new method for fitting spectral energy distributions (SEDs) to identify and constrain the physical properties of high-redshift (4 < z < 8) galaxies. Our approach uses an implementation of Bayesian based Markov Chain Monte Carlo (PiMC^2) that allows us to compare observations to arbitrarily complex models and to compute 95% credible intervals that provide robust constraints for the model parameters. The work is presented in 2 sections. In the first, we test PiMC^2 using simulated SEDs to not only confirm the recovery of the known inputs but to assess the limitations of the method and identify potential hazards of SED fitting when applied specifically to high redshift (z>4) galaxies. Our tests reveal five critical results: 1) the ability to confidently constrain metallicity, population ages, and Av all require photometric accuracy better than what is currently achievable (i.e. less than a few percent); 2) the ability to confidently constrain stellar masses (within a factor of two) can be achieved without the need for high-precision photometry; 3) the addition of IRAC photometry does not guarantee that tighter constraints of the stellar masses and ages can be defined; 4) different assumptions about the star formation history can lead to significant biases in mass and age estimates; and 5) we are able to constrain stellar age and Av of objects that are both young and relatively dust free. In the second part of the paper we apply PiMC^2 to 17 4 6 galaxies. Using PiMC^2, we are able to constrain the stellar mass of these objects and in some cases their stellar age and find no evidence that any of these sources formed at a redshift much larger than z_f=8, a time when the Universe was ~ 0.6 Gyr old.

astro-ph.GA↗