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Emission-Line Measurements

Emission-Line Parameters

The table below provides a compilation of emission-line parameters gathered through the development of the DAP. Many of them have not actually been fit by the DAP in any survey-level runs of the software and are simply collected here for reference.

Rest wavelengths are Ritz wavelengths in vacuum, collected from the NIST Atomic Spectra Database.

The "M1" and "E2" values are the Einstein Aki coefficients for the magnetic dipole and electric quadrupole transitions, respectively. These are collected to fix the expected flux ratio between specific line doublets. The expected flux ratio is:

$$\frac{f_1}{f_2} = \frac{\lambda_2}{\lambda_1}\ \cdot\ \frac{M1_1+E2_1}{M1_2+E2_2}$$

where, e.g., λ1 is the rest wavelength of the first line in the doublet.

Additionally, we have defined some nominal passbands used for calculations of the line equivalent width (EW), including the main passband centered on the line and blue and red sidebands that are used to construct a linear continuum beneath the emission line.

Name Rest λ (Å) M1 E2 EW Passband (Å) Blue Passband (Å) Red Passband (Å)
HeII1

3204.019
NeIII

3343.14
NeV

3346.783

 1.38e-1

6.2e-5
NeV

3426.864

 3.82e-1

3.9e-4
NI2

3467.513
H25

3670.5155
H24

3672.5279
H23

3674.8110
H22

3677.4160
H21

3680.4065
H20

3683.8627
H19

3687.8871
H18

3692.6119
H17

3698.2103
H16

3704.9132
H15

3713.0334
H14

3723.0035

3

3706.3 -- 3716.3

3738.6 -- 3748.6
OII

3727.092

 1.59e-4 1.86e-5

3716.3 -- 3738.3

3706.3 -- 3716.3

3738.6 -- 3748.6
OII

3729.875

 1.98e-6 2.86e-5

4

3706.3 -- 3716.3

3738.6 -- 3748.6
H13

3735.4365

5

3706.3 -- 3716.3

3738.6 -- 3748.6
H126

3751.2174

3746.2 -- 3756.2

3738.6 -- 3748.6

3756.6 -- 3766.6
H117

3771.7012

3761.7 -- 3781.7

3756.6 -- 3766.6

3779.1 -- 3789.1
${\rm H}\theta$8

3798.9757

3789.0 -- 3809.0

3776.5 -- 3791.5

3806.5 -- 3821.5
${\rm H}\eta$9

3836.4720

3826.5 -- 3846.5

3806.5 -- 3826.5

3900.2 -- 3920.2
NeIII

3869.86

 1.74e-1

3859.9 -- 3879.9

3806.5 -- 3826.5

3900.2 -- 3920.2
HeI10

3889.749

11

3806.5 -- 3826.5

3900.2 -- 3920.2
${\rm H}\zeta$12

3890.1506

3880.2 -- 3900.2

3806.5 -- 3826.5

3900.2 -- 3920.2
NeIII

3968.59

 5.40e-2

13

3938.6 -- 3958.6

3978.6 -- 3998.6
${\rm H}\epsilon$14

3971.1951

3961.2 -- 3981.2

3941.2 -- 3961.2

3981.2 -- 4001.2
HeI15

4027.328

4017.3 -- 4037.3

3997.3 -- 4017.3

4037.3 -- 4057.3
SII

4069.749

 1.92e-1 9.53e-8

4062.7 -- 4073.6

4049.7 -- 4062.7

4082.0 -- 4092.9
SII

4077.500

 7.72e-2 1.16e-6

4073.6 -- 4084.5

4049.7 -- 4062.7

4082.0 -- 4092.9
${\rm H}\delta$16

4102.8922

4092.9 -- 4112.9

4082.0 -- 4092.9

4112.9 -- 4132.9
${\rm H}\gamma$17

4341.6837

4331.7 -- 4351.7

4311.7 -- 4331.7

4349.7 -- 4358.7
OIII

4364.436

 1.71e+0

4358.7 -- 4374.4

4349.7 -- 4358.7

4374.4 -- 4384.4
HeI18

4472.734

4462.7 -- 4482.7

4442.7 -- 4462.7

4482.7 -- 4502.7
HeII19

4687.015

4677.0 -- 4697.0

4667.0 -- 4677.0

4697.0 -- 4707.0
ArIV20

4712.58

 9.6e-3
HeI21

4714.466

4707.0 -- 4722.0

4697.0 -- 4707.0

4722.0 -- 4732.0
ArIV

4741.45

7.2e-2

5.1e-3
${\rm H}\beta$22

4862.6830

4852.7 -- 4872.7

4798.9 -- 4838.9

4885.6 -- 4925.6
HeI

4923.3051

4913.3 -- 4933.3

4898.3 -- 4913.3

4933.3 -- 4948.3
OIII

4960.295

 6.21e-3 4.57e-6

4950.3 -- 4970.3

4930.3 -- 4950.3

4970.3 -- 4990.3
OIII

5008.240

 1.81e-2 3.52e-5

4998.2 -- 5018.2

4978.2 -- 4998.2

5028.2 -- 5048.2
HeI

5017.0769

23

4988.2 -- 4983.2

5028.2 -- 5048.2
ArIII

5193.27

 3.10e+0
NI

5199.349

 1.60e-5 4.34e-6

5189.3 -- 5209.3

5169.4 -- 5189.3

5211.7 -- 5231.7
NI

5201.705

 9.71e-7 6.59e-6

24

5169.4 -- 5189.4

5211.7 -- 5231.7
OI

5578.887

 1.26e+0
NII

5756.19

 1.14e+0
HeI25

5877.252

5867.2 -- 5887.2

5847.2 -- 5867.2

5887.2 -- 5907.2
NaI

5891.583
NaI

5897.558
OI

6302.046

 5.63e-3 2.11e-5

6292.0 -- 6312.0

6272.0 -- 6292.0

6312.0 -- 6332.0
OI

6365.536

 1.82e-3 3.39e-6

6355.5 -- 6375.5

6335.5 -- 6355.5

6375.5 -- 6395.5
NII

6549.86

 9.84e-4 9.22e-7

6542.9 -- 6556.9

6483.0 -- 6513.0

6623.0 -- 6653.0
HeII26

6561.890
${\rm H}\alpha$27

6564.608

6557.6 -- 6571.6

6483.0 -- 6513.0

6623.0 -- 6653.0
NII

6585.27

 2.91e-3 8.65e-6

6575.3 -- 6595.3

6483.0 -- 6513.0

6623.0 -- 6653.0
HeI

6679.9956

6670.0 -- 6690.0

6652.0 -- 6670.0

6690.0 -- 6708.0
SII

6718.295

 1.39e-5 1.88e-4

6711.3 -- 6725.3

6690.0 -- 6708.0

6748.0 -- 6768.0
SII

6732.674

 5.63e-4 1.21e-4

6725.7 -- 6739.7

6690.0 -- 6708.0

6748.0 -- 6768.0
HeI28

7067.144

7057.1 -- 7077.1

7037.1 -- 7057.1

7077.1 -- 7097.1
HeI

7067.65683
ArIII

7137.76

 3.21e-1

1.4e-3

7127.8 -- 7147.8

7107.8 -- 7127.8

7147.8 -- 7167.8
ArIV

7172.67

8.1e-1

9.8e-2
ArIV

7239.77

 4.44e-1 2.26e-1
ArIV

7265.33

 4.88e-1 1.90e-1
HeI

7283.3571
OII

7320.94

 5.19e-2

29

7291.0 -- 7311.0

7342.8 -- 7362.8
OII

7322.01

 8.37e-3 9.07e-2

7313.8 -- 7326.8

7291.0 -- 7311.0

7342.8 -- 7362.8
OII

7331.68

 9.32e-3 7.74e-2

7326.8 -- 7339.8

7291.0 -- 7311.0

7342.8 -- 7362.8
OII

7332.75

 1.49e-2 3.85e-2

30

7291.0 -- 7311.0

7342.8 -- 7362.8
ArIV

7334.17

 1.22e-1
ArIII

7753.24

8.3e-2

1.3e-4

7743.2 -- 7763.2

7703.2 -- 7743.2

7763.2 -- 7803.2
ArIII

8038.73

2.9e-5
P20

8394.703
P19

8415.630
P18

8440.274
P17

8469.581
P16

8504.819

8494.8 -- 8514.8

8474.8 -- 8494.8

8514.8 -- 8534.8
P15

8547.731

8534.8 -- 8557.7

8514.8 -- 8534.8

8557.7 -- 8587.7
P14

8600.754

8587.7 -- 8610.8

8557.7 -- 8587.7

8610.8 -- 8650.8
P13

8667.398

8657.4 -- 8677.4

8617.4 -- 8657.4

8677.4 -- 8717.4
P12

8752.876

8742.9 -- 8762.9

8702.9 -- 8742.9

8762.9 -- 8802.9
SIII

8831.8

 5.25e-6
${\rm P}\theta$

8865.216

8855.2 -- 8875.2

8815.2 -- 8855.2

8875.2 -- 8915.2
${\rm P}\eta$

9017.384

9007.4 -- 9027.4

8977.4 -- 9007.4

9027.4 -- 9057.4
SIII

9071.1

 1.85e-2 3.94e-5

9061.1 -- 9081.1

9026.1 -- 9061.1

9081.1 -- 9116.1
HeI31

9212.862
${\rm P}\zeta$

9231.546

9221.5 -- 9241.5

9181.5 -- 9221.5

9241.5 -- 9281.5
SIII

9533.2

 4.78e-2 2.09e-4

9525.5 -- 9540.9

9483.2 -- 9523.2

9558.6 -- 9598.6
${\rm P}\epsilon$

9548.588

9540.9 -- 9556.3

9483.2 -- 9523.2

9558.6 -- 9598.6
HeI32

9528.778
HeI33

10030.470
${\rm P}\delta$

10052.123

10042.1 -- 10062.1

10002.1 -- 10042.1

10062.1 -- 10102.1

Non-parametric Emission-Line Measurements

The DAP performs non-parametric measurements of the emission lines using a simple moment analysis. See mangadap.proc.emissionlinemoments and emission-line-moments. In survey-level runs of the DAP, we have typically paired the set of moment measurements and Gaussian models; however, the number of emission-line moment measurements need not be matched to the number of emission-line Gaussian models and vice versa.

Input Data Format

The parameters that define the emission-line moments to calculate are provided via the ~mangadap.par.emissionmomentsdb.EmissionMomentsDB object, which is built using an SDSS-style parameter file.

The columns of the parameter file are:

Parameter Format Description
index int Unique integer identifier of the emission line. Must be unique.
name str Name of the transition.
lambda float Rest frame wavelength of the emission line to analyze.
waveref str The reference frame of the wavelengths; must be either 'air' for air or 'vac' for vacuum.
primary float[2] A two-element vector with the starting and ending wavelength for the primary passband surrounding the emission line(s).
blueside float[2] A two-element vector with the starting and ending wavelength for a passband to the blue of the primary band.
redside float[2] A two-element vector with the starting and ending wavelength for a passband to the red of the primary band.

and an example file might look like this:

typedef struct {
    int index;
    char name[6];
    double lambda;
    char waveref[3];
    double primary[2];
    double blueside[2];
    double redside[2];
} DAPELB;

DAPELB   2  OIId    3728.4835  vac  { 3716.3  3738.3 } { 3706.3  3716.3 } { 3738.6  3748.6 }
DAPELB   3  OII     3729.875   vac  {   -1      -1   } {   -1      -1   } {   -1      -1   }

Note in the above example that the second set of parameters define nonsensical passbands with limits of {-1 -1}. This is used to signify that the moment parameters are "dummy" or placeholder parameters. This is used to create an empty channel in the output MAPS file and is used just to synchronize the channel indices between the non-parametric and Gaussian-fit results. That is, it's used to ensure that, e.g., the ${\rm H}\alpha$ measurements are in the same channel for both the EMLINE_SFLUX and EMLINE_GFLUX extensions in the datamodel-maps.

Changing the moment parameters

The moment measurements are performed by ~mangadap.proc.emissionlinemoments.EmissionLineMoments; see emission-line-moments. A set of parameter files that define a list of emission-line moment sets are provided with the DAP source distribution and located at $MANGADAP_DIR/mangadap/data/emission_bandpass_filters. The database you wish to use is selected by the passbands parameter in the relevant parameter block of the plan file. The keyword is simply the capitalized name of the file without the ".par" extension. For example, to use the elbmpl9.par database, the plan file would include

[default.eline_moments]
 passbands = 'ELBMPL9'

To provide a user-defined database, simply replace the passbands keyword with the name of the local file defining the database (in the format given above). For example,

[default.eline_moments]
 passbands = '/path/to/my/local/file/my_elb_database.par'

Gaussian Emission-Line Modeling

The DAP models the emission lines using single-component Gaussian functions. See mangadap.proc.emissionlinemoments and emission-line-modeling. In survey-level runs of the DAP, we have typically paired the set of moment measurements and Gaussian models; however, the number of emission-line moment measurements need not be matched to the number of emission-line Gaussian models and vice versa.

Input Data Format

The parameters that define the emission-line models to fit are provided via the ~mangadap.par.emissionlinedb.EmissionLineDB object, which is built using an SDSS-style parameter file.

The columns of the parameter file are:

Parameter Format Description
index int Unique integer identifier of the emission line. Must be unique. Specifically used when tying line parameters.
name str Name of the transition.
restwave float Rest frame wavelength of the emission line to analyze.
waveref str The reference frame of the wavelengths; must be either 'air' for air or 'vac' for vacuum.
action str A single character setting how the line should be treated. See emission-line-modeling-action.
tie_f str[2] A sequence of 2 10-character strings that indicate how the flux of the line should be tied to another line. The first element gives the index of the line to tie (see index above). The second element provides the constraint. Currently fluxes can only be tied by fixing the line flux ratio, and lines with tied fluxes must also have their velocity and velocity dispersions tied by equality. For example, to fix the ratio of the OIII 4959 line to the OIII 5007 line, the entry for the OIII 4959 line should be { 14 =0.34 }, where 14 is the index number of the OIII 5007 in the file and the flux in the OIII 4959 line is always 0.34 times the flux in the OIII 5007 line.
tie_v str[2] A sequence of 2 10-character strings that indicate how the velocity of the line should be tied to another line. The first element gives the index of the line to tie (see index above). The second element provides the constraint. Velocities can be tied by equality (using =) or tied by inequality (see below); however, tying by inequality is not well tested.
tie_s str[2] A sequence of 2 10-character strings that indicate how the velocity dispersion of the line should be tied to another line. The first element gives the index of the line to tie (see index above). The second element provides the constraint. Velocity dispersions can can be tied by equality (using =) or tied by inequality (see below).
blueside float[2] A two-element vector with the starting and ending wavelength for a passband to the blue of the primary band.
redside float[2] A two-element vector with the starting and ending wavelength for a passband to the red of the primary band.

and an example file might look like this:

typedef struct {
    int index;
    char name[6];
    double restwave;
    char waveref[3];
    char action;
    char tie_f[2][10];
    char tie_v[2][10];
    char tie_s[2][10];
    double blueside[2];
    double redside[2];
} DAPEML;

DAPEML   2  OII     3727.092   vac  f  { None   None }  {   34      = }  { None   None }  {  3706.3  3716.3 }  {  3738.6  3748.6 }
DAPEML   3  OII     3729.875   vac  f  { None   None }  {    2      = }  {    2      = }  {  3706.3  3716.3 }  {  3738.6  3748.6 }
DAPEML  23  Hb      4862.6830  vac  f  { None   None }  {   34      = }  {   34    1.4 }  {  4798.9  4838.9 }  {  4885.6  4925.6 }
DAPEML  33  NII     6549.86    vac  f  {   35  =0.34 }  {   35      = }  {   35      = }  {  6483.0  6513.0 }  {  6623.0  6653.0 }
DAPEML  34  Ha      6564.608   vac  f  { None   None }  { None   None }  { None   None }  {  6483.0  6513.0 }  {  6623.0  6653.0 }
DAPEML  35  NII     6585.27    vac  f  { None   None }  {   34      = }  { None   None }  {  6483.0  6513.0 }  {  6623.0  6653.0 }

Note

  • Both the emission-line moments database and the emission-line modeling database define the sidebands used for the equivalent width calculations. Nominally, these should be the same, but it's up to the person that writes the two parameter files to make sure that is true.
  • Format changes:
    • version 3.1.0: Many parameters removed that were used by the deprecated ~mangadap.proc.elric.Elric fitter.
    • version 4.1.0: Added ability to tie the three parameters to different lines; i.e., velocity can be tied to one line while dispersion is tied to a different one.

Emission-Line "Actions"

Emission-Line Tying

Line tying in the DAP uses the functionality in ppxf in a limited and abstracted way.

Tying fluxes effectively means that the lines are put in the same emission-line template. This is why, currently, any lines with tied fluxes must also tie their velocity and velocity dispersion. Also, the DAP currently does not allow tying fluxes using inequalities.

Tying kinematics can be done with equality or inequality. For equality, use the = character, as in the example file above. Unlike the fluxes, the kinematics cannot be tied to be, e.g., a specific fraction of the value of the tied line. (I.e., you can't tie the dispersion to be exactly half of the dispersion of the tied line). For inequality, there are a couple of options:

  1. Use >N or <N to force the value to be greater or less than the provided fraction of the the value of the tied line. E.g., to force the dispersion of one component to be at least 1.5 times larger than the tied line, use >1.5. Using > or < is equivalent to >1 and <, respectively.
  2. To bound the value between both upper and lower limits, you must use a single fixed fractional bound. For example, setting the tied value for the dispersion to 1.4 means that the best-fitting dispersion must be greater than 1/1.4 and less than 1.4 times the dispersion of the tied line.

Warning

Although line tying has been experimented with for MaNGA data, much of the inequality tying is not well tested.

Emission-Line "Modes"

Warning

This parameter is now DEPRECATED in favor of the tie parameter.

Changing the modeling parameters

The moment measurements are performed by ~mangadap.proc.emissionlinemoments.EmissionLineMoments; see emission-line-moments. A set of parameter files that define a list of emission-line moment sets are provided with the DAP source distribution and located at $MANGADAP_DIR/mangadap/data/emission_bandpass_filters. The database you wish to use is selected by the passbands parameters in the relevant parameter block of the plan file. The keyword is simply the capitalized name of the file without the ".par" extension. To provide a user-defined database, simply replace the passbands keyword with the name of the local file defining the database (in the format given above).

The emission-line modeling is performed by ~mangadap.proc.emissionlinemodel.EmissionLineModel; see emission-line-modeling. A set of files that define a list of emission-line model parameter sets are provided with the DAP source distribution and located at $MANGADAP_DIR/mangadap/data/emission_lines. The database you wish to use is selected by the emission_lines parameter in the relevant parameter block of the plan file. The keyword is simply the capitalized name of the file without the ".par" extension. For example, to use the elpmpl11.par database, the plan file would include

[default.eline_fits.fit]
 emissionpassbands = 'ELPMPL11'

To provide a user-defined database, simply replace the passbands keyword with the name of the local file defining the database (in the format given above). For example,

[default.eline_fits.fit]
 emissionpassbands = '/path/to/my/local/file/my_elp_database.par'

  1. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  2. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  3. No primary band defined because it overlaps with another line.↩

  4. No primary band defined because it overlaps with another line.↩

  5. No primary band defined because it overlaps with another line.↩

  6. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  7. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  8. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  9. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  10. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  11. No primary band defined because it overlaps with another line.↩

  12. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  13. No primary band defined because it overlaps with another line.↩

  14. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  15. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  16. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  17. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  18. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  19. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  20. Provided magnetic dipole coefficient is actually its sum with the electric quadrupole coefficient.↩

  21. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  22. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  23. No primary band defined because it overlaps with another line.↩

  24. No primary band defined because it overlaps with another line.↩

  25. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  26. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  27. Center of gravity of the blending of fine-structure lines assuming Boltzmann populations in an optically thin plasma; see, e.g.: https://physics.nist.gov/cgi-bin/ASBib1/get_ASBib_ref.cgi?db=el&db_id=&comment_code=c69&element=H&spectr_charge=1&ref=&type=↩

  28. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  29. No primary band defined because it overlaps with another line.↩

  30. No primary band defined because it overlaps with another line.↩

  31. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  32. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩

  33. Wavelength based on a simple average of wavelengths for many fine-structure transitions.↩