1603.08522
First identification of direct collapse black hole candidates in the early universe in CANDELS/GOODS-S
Pacucci, Ferrara, Grazian, Fiore, Giallongo
The first BH seeds, formed when the universe was younger than 500 Myr, are recognized to play an important role for the growth of early (z~7) SMBHs. While progresses have been made in understanding their formation and growth, their observational signatures remain largely unexplored. As a result, no detection of such sources has been confirmed so far. Supported by numerical simulations, present a novel photometric method to identify BH seed candidates in deep multi-wavelength surveys. Predict that these highly-obscured sources are characterized by a steep spectrum in the IR (1.6-4.5 um), i.e., by very red colors. The method selects the only 2 objects with a robust x-ray detection found in the CANDELS/GOODS-S survey with a photometric redshift z>6. Fitting their IR spectra only with a stellar component would require unrealistic SFRs (>2000 Msun/yr). To date, the selected objects represent the most promising BH seed candidates, possibly formed via the direct collapse BH scenario, with predicted mass > 1e5 Msun. While this result is based on the best photometric observations of high-z sources available to date, additional progress is expected from spectroscopic and deeper X-ray data. Upcoming observatories, like the JWST, will greatly expand the scope of this work.
1603.08609
Covariance in the Thermal SZ-Weak lensing mass scaling relation of galaxy clusters
Shirasaki, Nagai, Lau
Investigate the origin of observed scatter in the tSZ-WL scaling relation, using mock maps of galaxy clusters extracted from cosmo hydro sims. Show that the inferred intrinsic scatter from mock tSZ-WL analyses is considerably larger than the intrinsic scatter measured in simulations, and comparable to the scatter in the observed tSZ-WL relation. Show that this enhanced scatter originates form the combination of the projection of correlated structures along the line of sight and the uncertainty in the cluster radius associated with WL mass estimates, causing the amplitude of the scatter to depend on the covariance between tSZ and WL signals. Present a statistical model to recover the unbiased cluster scaling relation and cosmological parameter by taking into account the covariance in the tSZ-WL mass relation from multi-wavelength cluster surveys.
1603.08626
The composite spectrum of BOSS quasars selected for suites of the LYman-alpha forest
Harris, Jensen, Suzuki, et al
BOSS has collected more than 150,000 2.1<z<3.5 quasar spectra since 2009. Using this unprecedented sample, create a composite spectrum in the rest-frame of 102,150 quasar spectra from 800A to 3300A at a S/N ratio close to 1000 per pixel (Delta nu of 69 km/s). Included in this analysis is a correction to account for flux calibration residuals in the BOSS spectrophotometry. Determine the spectral index as a function of z of the full sample, warp the composite spectrum to match the median spectral index, and compare the resulting spectrum to SDSS photometry used in target selection. The quasar composite matches the color of the quasar population to within 0.02 magnitudes in g-r, 0.03 magnitudes in r-i, and 0.01 magnitudes in i-z over 2.2<z<2.6. The composite spectrum deviates from the imaging photometry by 0.05 mag around z=2.7, likely due to differences in target selection as the quasar colors become similar to the stellar locus at this redshift. Finally, characterize the line features in the high S/N composite and identity 9 faint lines not found in the previous composite spectrum from SDSS.
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