Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFirst results from the ALHAMBRA-Survey
134
0
0.0
(
0
)
Added by
Alberto Fernandez-Soto
Publication date
2008
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We present the first results from the ALHAMBRA survey. ALHAMBRA will cover a relatively wide area (4 square degrees) using a purposely-designed set of 20 medium-band filters, down to an homogeneous magnitude limit AB~25 in most of them, adding also deep near-infrared imaging in JHK. To this aim we are using the Calar Alto 3.5m telescope. A small area of the ALHAMBRA survey has already been observed through our complete filter set, and this allows for the first time to check all the steps of the survey, including the pipelines that have been designed for the project, the fulfilment of the data quality expectations, the calibration procedures, and the photometric redshift machinery for which ALHAMBRA has been optimised. We present here the basic results regarding the properties of the galaxy sample selected in a 15x15 square arcmin area of the ALHAMBRA-8 field, which includes approximately 10000 galaxies with precise photometric redshift measurements. In a first estimate, approximately 500 of them must be galaxies with z>2.
rate research
Read More
We have attempted to analyse all the available data taken by XMM-Newton as it slews between targets. This slew survey, the resultant source catalogue and the analysis procedures used are described in an accompanying paper. In this letter we present the initial science results from the survey. To date, detailed source-searching has been performed in three X-ray bands (soft, hard and total) in the EPIC-pn 0.2-12 keV band over ~6300 sq.degrees (~15% of the sky), and of order 4000 X-ray sources have been detected (~55% of which have IDs). A great variety of sources are seen, including AGN, galaxies, clusters and groups, active stars, SNRs, low- and high-mass XRBs and white dwarfs. In particular, as this survey constitutes the deepest ever hard-band 2-12 keV all-sky survey, a large number of hard sources are detected. Furthermore, the great sensitivity and low-background of the EPIC-pn camera are especially suited to emission from extended sources, and interesting spatial structure is observed in many supernova remnants and clusters of galaxies. The instrument is very adept at mapping large areas of the X-ray sky. Also, as the slew survey is well matched to the ROSAT all-sky survey, long-term variability studies are possible, and a number of extremely variable X-ray sources, some possibly due to the tidal disruption of stars by central supermassive black holes, have been discovered.
We present the Calan-Yale Deep Extragalactic Research (CYDER) Survey. The broad goals of the survey are the study of stellar populations, the star formation history of the universe and the formation and evolution of galaxies. The fields studied include Chandra deep pointings in order to characterize the X-ray faint populations. Here we present the results on the first fields studied. We find that the redshift distribution is consistent with that found in the Chandra Deep Field North. The distribution of hardness ratios is, however, softer in our sample. We find a high redshift quasar, CXOCY J125304.0-090737 at z=4.179, which suggests that the abundance of low luminosity high redshift quasars may be larger than what would be expected from reasonable extrapolations from the quasar optical luminosity function.
Results from the first two years of data from the Taiwanese-American Occultation Survey (TAOS) are presented. Stars have been monitored photometrically at 4 Hz or 5 Hz to search for occultations by small (~3 km) Kuiper Belt Objects (KBOs). No statistically significant events were found, allowing us to present an upper bound to the size distribution of KBOs with diameters 0.5 km < D < 28 km.
We report on the results from the first six months of the Catalina Real-time Transient Survey (CRTS). In order to search for optical transients with timescales of minutes to years, the CRTS analyses data from the Catalina Sky Survey which repeatedly covers twenty six thousand of square degrees on the sky. The CRTS provides a public stream of transients that are bright enough to be followed up using small telescopes. Since the beginning of the survey, all CRTS transients have been made available to astronomers around the world in real-time using HTML tables, RSS feeds and VOEvents. As part of our public outreach program the detections are now also available in KML through Google Sky. The initial discoveries include over 350 unique optical transients rising more than two magnitudes from past measurements. Sixty two of these are classified as supernovae, based on light curves, prior deep imaging and spectroscopic data. Seventy seven are due to cataclysmic variables (only 13 previously known), while an additional 100 transients were too infrequently sampled to distinguish between faint CVs and SNe. The remaining optical transients include AGN, Blazars, high proper motions stars, highly variable stars (such as UV Ceti stars) and transients of an unknown nature. Our results suggest that there is a large population of SNe missed by many current supernova surveys because of selection biases. These objects appear to be associated with faint host galaxies. We also discuss the unexpected discovery of white dwarf binary systems through dramatic eclipses.
We present constraints on the abundance of carbon-monoxide in the early Universe from the CO Power Spectrum Survey (COPSS). We utilize a data set collected between 2005 and 2008 using the Sunyaev-Zeldovich Array (SZA), which were previously used to measure arcminute-scale fluctuations of the CMB. This data set features observations of 44 fields, covering an effective area of 1.7 square degrees, over a frequency range of 27 to 35 GHz. Using the technique of intensity mapping, we are able to probe the CO(1-0) transition, with sensitivity to spatial modes between $k=0.5{-}2 h,textrm{Mpc}^{-1}$ over a range in redshift of $z=2.3{-}3.3$, spanning a comoving volume of $3.6times10^{6} h^{-3},textrm{Mpc}^{3}$. We demonstrate our ability to mitigate foregrounds, and present estimates of the impact of continuum sources on our measurement. We constrain the CO power spectrum to $P_{textrm{CO}}<2.6times10^{4} mutextrm{K}^{2} (h^{-1},textrm{Mpc})^{3}$, or $Delta^{2}_{textrm{CO}}(k! = ! 1 h,textrm{Mpc}^{-1})<1.3 times10^{3} mutextrm{K}^{2}$, at $95%$ confidence. This limit resides near optimistic predictions for the CO power spectrum. Under the assumption that CO emission is proportional to halo mass during bursts of active star formation, this corresponds to a limit on the ratio of $textrm{CO}(1{-}0)$ luminosity to host halo mass of $A_{textrm{CO}}<1.2times10^{-5} L_{odot} M_{odot}^{-1}$. Further assuming a Milky Way-like conversion factor between CO luminosity and molecular gas mass ($alpha_{textrm{CO}}=4.3 M_{odot} (textrm{K} textrm{km} textrm{s}^{-1} textrm{pc}^{-2})^{-1}$), we constrain the global density of molecular gas to $rho_{zsim3}(M_{textrm{H}_{2}})leq 2.8 times10^{8} M_{odot} textrm{Mpc}^{-3}$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
