A Galactic Center Search for Extraterrestrial Intelligent Signals

1997 ◽  
Vol 161 ◽  
pp. 653-656 ◽  
Author(s):  
Woodruff T. Sullivan ◽  
Kelvin J. Wellington ◽  
G. Seth Shostak ◽  
Peter R. Backus ◽  
James M. Cordes
Keyword(s):  
Radio Telescope ◽  
Signal Analysis ◽  
Luminosity Function ◽  
Galactic Center ◽  
Spectrum Analyzer ◽  
Analysis System

AbstractIn June 1995 we used the Parkes 64-m radio telescope to search for narrowband or pulsing signals of extraterrestrial intelligent (ETI) origin from the direction of the galactic center. This strategy was chosen so as to maximize the number of possibly detectable ETI signals within the beam, assuming that they are associated with stars and that their luminosity function is such that they can be detected at a distance of at least a few kiloparsecs. A total of 190 1.2–minute integrations were taken in a region of size 5.0° × 0.6° centered on the galactic center. Many positions in this region were observed 2 or 3 times in order to allow for the possibility of strong interstellar scintillations arising in any ETI signal. The spectrum analyzer was that of Project Phoenix, configured such that it covered both circular polarizations over a 20-MHz bandwidth centered on 1425.0 MHz. This bandwidth was divided into 28.7 million channels with separations of 0.64 Hz. The signal analysis system searched both for slow pulses (periods of at least 2 sec) and narrowband signals with drifts from 0 to 1 Hz/sec. A second antenna located 200 km away was used for immediate follow-up on all candidate signals. No signals of ETI origin were found. A later search of smoothed spectra with 640 Hz resolution also revealed no new features not attributable to manmade interference.

scholarly journals The NIBLES bivariate luminosity–H I mass distribution function revised using Arecibo follow-up observations

2020 ◽  
Vol 642 ◽  
pp. A175
Author(s):  
Z. Butcher ◽  
W. van Driel ◽  
S. Schneider
Keyword(s):  
Mass Distribution ◽  
Radio Telescope ◽  
Luminosity Function ◽  
Mass Function ◽  
Bivariate Analysis ◽  
Dimensional Distribution ◽  
Low Mass ◽  
The One ◽  
Mass Distribution Function

We present a modified optical luminosity–H I mass bivariate luminosity function based on H I line observations from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES), including data from our new, four times more sensitive follow-up H I line observations obtained with the Arecibo radio telescope. The follow-up observations were designed to probe the underlying H I mass distribution of the NIBLES galaxies that were undetected or marginally detected in H I at the Nançay Radio Telescope. Our total follow-up sample consists of 234 galaxies, and it spans the entire luminosity and color range of the parent NIBLES sample of 2600 nearby (900 <  cz <  12 000 km s−1) SDSS galaxies. We incorporated the follow-up data into the bivariate analysis by scaling the NIBLES undetected fraction by an Arecibo-only distribution. We find the resulting increase in low H I mass-to-light ratio densities to be about 10% for the bins −1.0 ≤ log(MHI/M⊙/Lr/L⊙) ≤ −0.5, which produces an increased H I mass function (HIMF) low mass slope of α = −1.14 ± 0.07, being slightly shallower than the values of −1.35 ± 0.05 obtained by recent blind H I surveys. Applying the same correction to the optically corrected bivariate luminosity function from our previous paper produces a larger density increase of about 0.5 to 1 dex in the lowest H I mass-to-light ratio bins for a given luminosity while having a minimal effect on the resulting HIMF low mass slope, which still agrees with blind survey HIMFs. This indicates that while low H I-mass-to-light ratio galaxies do not contribute much to the one-dimensional HIMF, their inclusion has a significant impact on the densities in the two-dimensional distribution.

scholarly journals The Luminosity Function of White Dwarfs in the Local Disk and Halo

1989 ◽  
Vol 114 ◽  
pp. 15-23 ◽  
Author(s):  
James Liebert ◽  
Conard C. Dahn ◽  
David G. Monet
Keyword(s):  
White Dwarfs ◽  
Luminosity Function ◽  
Solar Neighborhood ◽  
Star Formation History ◽  
Empirical Estimates ◽  
Formation History ◽  
History Of ◽  
Cool White Dwarfs ◽  
Local Disk

The luminosity function (LF) and total space density of white dwarfs in the solar neighborhood contain important information about the star formation history of the stellar population, and provide an independent method of measuring its age. The first empirical estimates of the LF for degenerate stars were those of Weidemann (1967), Kovetz and Shaviv (1976) and Sion and Liebert (1977). The follow-up investigations made possible by the huge Luyten Palomar proper motion surveys, however, added many more faint white dwarfs to the known sample. While the number of known cool white dwarfs grew to nearly one hundred, these did not include any that were much fainter intrinsically than the coolest degenerates found from the early Luyten, van Biesbroeck and Eggen-Greenstein lists.

Near-infrared biomedical signal analysis system

1999 ◽  
Author(s):  
Jiangsheng Yu ◽  
Qingming Luo ◽  
Dan Zhu ◽  
Qiang Lu ◽  
Ruan Yu
Keyword(s):  
Signal Analysis ◽  
Near Infrared ◽  
Biomedical Signal ◽  
Biomedical Signal Analysis ◽  
Analysis System

scholarly journals Megaparsec-scale structure around the protocluster core SPT2349–56 at z = 4.3

2020 ◽  
Vol 495 (3) ◽  
pp. 3124-3159 ◽  
Author(s):  
Ryley Hill ◽  
Scott Chapman ◽  
Douglas Scott ◽  
Yordanka Apostolovski ◽  
Manuel Aravena ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Far Infrared ◽  
Main Structure ◽  
Star Forming ◽  
Galaxy Groups ◽  
The Core ◽  
Order Of Magnitude ◽  
Number Counts ◽  
Limited Coverage

ABSTRACT We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349–56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4–3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349–56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$  M⊙, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349–56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊙ yr−1 Mpc−3; this may be an order of magnitude greater than the most extreme examples seen in simulations.

scholarly journals A fast radio burst in the direction of the Virgo Cluster

2019 ◽  
Vol 490 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Devansh Agarwal ◽  
Duncan R Lorimer ◽  
Anastasia Fialkov ◽  
Keith W Bannister ◽  
Ryan M Shannon ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Confidence Limit ◽  
Luminosity Function ◽  
High Sensitivity ◽  
Virgo Cluster ◽  
Dispersion Measure ◽  
Nearby Galaxy ◽  
The Mean ◽  
Fast Radio Burst

ABSTRACT The rate of fast radio bursts (FRBs) in the direction of nearby galaxy clusters is expected to be higher than the mean cosmological rate if intrinsically faint FRBs are numerous. In this paper, we describe a targeted search for faint FRBs near the core of the Virgo Cluster using the Australian Square Kilometre Array Pathfinder telescope. During 300 h of observations, we discovered one burst, FRB 180417, with dispersion measure (DM) = 474.8 cm−3 pc. The FRB was promptly followed up by several radio telescopes for 27 h, but no repeat bursts were detected. An optical follow-up of FRB 180417 using the PROMPT5 telescope revealed no new sources down to an R-band magnitude of 20.1. We argue that FRB 180417 is likely behind the Virgo Cluster as the Galactic and intracluster DM contribution are small compared to the DM of the FRB, and there are no galaxies in the line of sight. The non-detection of FRBs from Virgo constrains the faint-end slope, α &lt; 1.52 (at 68 per cent confidence limit), and the minimum luminosity, Lmin ≳ 2 × 1040 erg s−1 (at 68 per cent confidence limit), of the FRB luminosity function assuming cosmic FRB rate of 104 FRBs per sky per day with flux above 1 Jy located out to redshift of 1. Further FRB surveys of galaxy clusters with high-sensitivity instruments will tighten the constraints on the faint end of the luminosity function and, thus, are strongly encouraged.

A Wide Survey in NH3 Lines of the Central 200 pc Around the Galactic Center with Kagoshima 6 Meter Radio Telescope

2008 ◽  
pp. 361-361
Author(s):  
Takumi Nagayama ◽  
Toshihiro Omodaka ◽  
Toshihiro Handa ◽  
Tsuyoshi Sawada ◽  
Hayati Bebe Iahak ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Galactic Center

Methodology of the Modular ECG Analysis System MEANS

1990 ◽  
Vol 29 (04) ◽  
pp. 346-353 ◽  
Author(s):  
G. van Herpen ◽  
J. H. van Bemmel ◽  
J. A. Kors
Keyword(s):  
Software Package ◽  
Signal Analysis ◽  
Basic Structure ◽  
Modular Approach ◽  
Entire System ◽  
Ecg Analysis ◽  
Study Evaluation ◽  
Interpretation System ◽  
Overall Evaluation ◽  
Analysis System

AbstractThe methodology, used in the Modular ECG Analysis System (MEANS) is described. MEANS consists of modules for signal analysis and diagnostic classification. The basic structure of the modular interpretation system remained intact over a period of 20 years, while all modules underwent many changes as a function of experience and insight, and the continuously changing information technology. The article describes the advantages of a modular approach to decision-support systems, the most important ones being easier maintenance of the software package and separate optimization and testing of each module. The overall evaluation of MEANS was done in the CSE study. Evaluation results for modules and for the entire system are presented.

scholarly journals Pulsar Searches at Effelsberg

2004 ◽  
Vol 218 ◽  
pp. 133-134 ◽  
Author(s):  
B. Klein ◽  
M. Kramer ◽  
P. Müller ◽  
R. Wielebinski
Keyword(s):  
Radio Telescope ◽  
Galactic Center ◽  
Millisecond Pulsars ◽  
Highly Dispersed ◽  
L Band ◽  
Under Construction ◽  
5 Ghz ◽  
Key Aspects ◽  
Pulsar Searches

We report on the progress of our search for highly dispersed pulsars near the Galactic Center at 5 GHz using the 100-m radio telescope in Effelsberg. We also present key aspects of our new survey for millisecond pulsars at 21 cm in parts of the northern sky. This survey will greatly benefit from the L-band multibeam receiver and a new FFT-based backend which are currently under construction at the MPIfR.

scholarly journals Euclid preparation

2019 ◽  
Vol 631 ◽  
pp. A85 ◽  
Author(s):  
◽  
R. Barnett ◽  
S. J. Warren ◽  
D. J. Mortlock ◽  
J.-G. Cuby ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Near Infrared ◽  
Selection Method ◽  
Early Type ◽  
Data Release ◽  
Rate Of Decline ◽  
Current Record

We provide predictions of the yield of 7 <  z <  9 quasars from the Euclid wide survey, updating the calculation presented in the Euclid Red Book in several ways. We account for revisions to the Euclid near-infrared filter wavelengths; we adopt steeper rates of decline of the quasar luminosity function (QLF; Φ) with redshift, Φ ∝ 10k(z − 6), k = −0.72, and a further steeper rate of decline, k = −0.92; we use better models of the contaminating populations (MLT dwarfs and compact early-type galaxies); and we make use of an improved Bayesian selection method, compared to the colour cuts used for the Red Book calculation, allowing the identification of fainter quasars, down to JAB ∼ 23. Quasars at z >  8 may be selected from Euclid OYJH photometry alone, but selection over the redshift interval 7 <  z <  8 is greatly improved by the addition of z-band data from, e.g., Pan-STARRS and LSST. We calculate predicted quasar yields for the assumed values of the rate of decline of the QLF beyond z = 6. If the decline of the QLF accelerates beyond z = 6, with k = −0.92, Euclid should nevertheless find over 100 quasars with 7.0 <  z <  7.5, and ∼25 quasars beyond the current record of z = 7.5, including ∼8 beyond z = 8.0. The first Euclid quasars at z >  7.5 should be found in the DR1 data release, expected in 2024. It will be possible to determine the bright-end slope of the QLF, 7 <  z <  8, M1450 <  −25, using 8 m class telescopes to confirm candidates, but follow-up with JWST or E-ELT will be required to measure the faint-end slope. Contamination of the candidate lists is predicted to be modest even at JAB ∼ 23. The precision with which k can be determined over 7 <  z <  8 depends on the value of k, but assuming k = −0.72 it can be measured to a 1σ uncertainty of 0.07.

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