Table of Contents
To upload a single galaxy go to http://lasd.lyman-alpha.com/uploadsingle
You will need to prepare a file with the spectrum according to How to prepare the spectrum file for upload and you need to have the following information prepared.
- continuum removal,
- redshift estimation, and
- computation of the spectral quantities.
We describe each of these steps in more detail in our paper.
In order to quantify the uncertainty of the computed spectral quantities, we repeat the calculation 100 times and in between 'shuffle' the spectrum. That is, we draw a new flux in each bin from a Gaussian with mean and standard deviation being the reported flux and error, respectively. We then repeat we repeat the redshift estimation process, and if the systemic redshift (and uncertainty) is given by the user, draw a new redshift from a Gaussian defined by these values.
Apart from the data analysis, LASD will also go \& get the full bibtex entry from SAO/NASA ADS to make it easier for the downloader to cite the appropriate papers. We will also send out a tweet to twitter page to let the world know about the most recent upload :)
Press on "Download data" in the menu above. Then you have the choiice between downloading the spectra (i.e., the original upload if the uploader has allowed this) or the measurements created by LASD. Yes, it's that easy ;)
A lot of work went into building planning \& executing the observations as well as building this website. When using data of LASD in your publication, we therefore kindly ask you to
- cite the original observational papers of the data you used. For this, we provide the full bibtex entries in the download. ,
- cite our paper Runnholm et al. (2042) ,
- and add a footnote to the LASD URL "http://lasd.lyman-alpha.com" or "www.lyman-alpha.com".
import pandas as pd df = pd.read_csv('zsysdf.ascii', delim_whitespace=True)
This will return a pandas dataframe object with all galaxies for which there are systematic redshifts.
import pandas as pd df = pd.read_csv('zsysdf.ascii', delim_whitespace=True) # Select subset based on Lya Equivalent width lya_emitter_subset = df[df['EW'] >= 20]
Multiple Object Uploadsee the guide below. The second is a tarball containing the relevant spectral files.
The spectra should be formatted according to the guide below. Additionally all the files should be either located in the root directory of the tarball (a so called tar-bomb) or the subdirectory should be specified in the filename column of the table file with the format 'subdirectory/name_of_spectrum_file.dat' or equivalent unix readable path.
- All lines prefaced with '#' are ignored as comments
- The file is required to have 3 columns separated by tabs
- The three columns need to be Wavelength, Flux, and Error
- The units of the columns should be Ångström and erg/s/cm2 respectively. For bulk upload a prefactor for the flux such as 1e17, as well as other units for flux and wavelength can be specified in the table file.
-       - name of the associated spectrum file in the tarball
-       - name of theinstrument with which the observations were made
-       - Approximate spectral resolution
-       - Redshift of the source
-       - Estimated uncertainty on the redshift
-       - Whether the redshift is an estimate or a measurement of the systemic redshift.
Boolean - Needs to be either 'True' or 'False'.
-       - Right ascension of the source. Preferred format: degrees
-       - Declination of the source. Preferred format: degrees
-       - Whether the raw spectrum is downloadable or not. Boolean - True or False
-       - Bibcode or URL from the ADS, for example: 2015A&A...583A..55O or http://adsabs.harvard.edu/abs/2016ApJ...828...49H.
- The following keywords are also recognized but are optional:
-       - A prefactor for the fluxvector in the spectrum.
-       - Units of the fluxvector. Example: 'erg / (s cm2 AA)'
-       - Units of the wavelength array. Default: 'AA'
-       - Name of the object.
We also perform this analysis once using the detected redshift (see ... on how the detection is performed), and (if available) using the systemic redshift given at upload.
Below is a table of all our measured quantities.
|Dx_max||Peak separation between maximum luminosity densities.||km/s|
|Dx_mean||Peak separation between first moments of both sides.||km/s|
|EW||Equivalent width of line.||Å|
|FWHM_max||Full-width at half maximum of highest peak.||km/s|
|FWHM_neg||Full-width at half maximum of blue side.||km/s|
|FWHM_pos||Full-width at half maximum of red side.||km/s|
|F_cont||Level of continuum.||erg/s/(km/s)|
|F_lc||Luminosity density at line center.||erg/s/(km/s)|
|F_max||Luminosity density of highest peak.||erg/s/(km/s)|
|F_neg_max||Luminosity density of highest peak on blue side.||erg/s/(km/s)|
|F_pos_max||Luminosity density of highest peak on red side.||erg/s/(km/s)|
|F_valley||Luminosity density of minimum between peaks.||erg/s/(km/s)|
|L_neg||Luminosity of blue side.||erg/s|
|L_pos||Luminosity of red side.||erg/s|
|R_F_cut_neg||Ratio of maximum luminosity density and peak detection threshold on blue side.|
|R_F_cut_pos||Ratio of maximum luminosity density and peak detection threshold on blue side.|
|R_F_lc_max||Ratio of luminosity density at line center and maximum peak height.|
|R_F_pos_neg||Ratio of luminosity density at red and blue peak.|
|R_F_valley_max||Ratio of luminosity density in the `valley` between the peaks and the maximum peak.|
|R_L_cut_neg||Ratio of blueward luminosity and peak detection threshold.|
|R_L_cut_pos||Ratio of redward luminosity and peak detection threshold.|
|R_L_pos_neg||Ratio of redward over blueward luminosity.|
|W_neg_std||Blue peak width as measured by square-root of second moment.||km/s|
|W_pos_std||Red peak width as measured by square-root of second moment.||km/s|
|neg_peak_fraction||Fraction of times a blue peak was detected.|
|pos_peak_fraction||Fraction of times a red peak was detected.|
|skew_neg||Pearson's moment coefficient of skewness of blue side.|
|skew_pos||Pearson's moment coefficient of skewness of red side.|
|x_max||Highest peak position determined by maximum luminosity density.||km/s|
|x_neg_max||Peak position determined by maximum luminosity density on blue side.||km/s|
|x_neg_mean||Peak position determined by weighted mean on blue side.||km/s|
|x_pos_max||Peak position determined by maximum luminosity density on red side.||km/s|
|x_pos_mean||Peak position determined by weighted mean on red side.||km/s|
|x_valley||Position of `valley` between the keys.||km/s|
|z||Systemic redshift of source.|