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the young radio sources , including compact steep spectrum ( css ) and gigahertz peaked spectrum ( gps ) radio sources , are believed to represent the earliest stages in the evolution of the powerful radio galaxies @xcite .
some of them are found to be associated with galaxies mergers @xcite or ultraluminous infrared galaxies ( ulirgs ) @xcite .
recent observations also manifest that some radio - loud narrow - line seyfert 1 galaxies / quasars ( nls1s ) have the radio properties consistent with css radio sources @xcite .
nls1s are classified based on their narrow balmer lines ( with the full width at half maximum , fwhm @xmath1 ) , small ratio between [ o iii]@xmath25007 and h@xmath0 ( [ o iii]@xmath25007/h@xmath0 @xmath3 3 ) and strong emission of fe ii complexes ( fe ii @xmath24570/h@xmath0 @xmath4 0.5 , ) .
these features are explained as a result of relatively small mass of the central black hole with high accretion rate ( @xcite , but also see @xcite ) .
thus nls1s are suggested to be during the early stage of the accretion activities .
the accretion rates of young radio sources are found to be relatively high , with the average value similar with nls1s @xcite .
thus the young radio sources can also stand during the early stage of accretion activities .
moreover , there is another similar feature between the young radio sources and nls1s . that is the blue wing of narrow [ o iii ] @xcite .
this feature is always explained as the outflow originated from the disk wind or galactic wind .
some results indicate that the strength of the blueshift is related to the eddington ratio @xcite , while other explanations refer to the jet - ism interaction @xcite .
although the common radio properties between nls1s and young radio sources have been discussed frequently in the literature , the common optical properties between them are less discussed . in this paper
, we obtain the optical spectra of four young radio sources , and explore their emission lines properties . throughout this paper , the luminosity
is calculated using a @xmath5cdm cosmology model with h=0.71 , @xmath6=0.27 , @xmath7=0.73 .
the spectra were obtained between 2014 and 2015 , with the yunnan faint object spectrograph and camera ( yfosc ) on the lijiang 2.4 m telescope in yunnan observatories .
the yfosc is equipped with a back - illuminated , blue sensitive ccd with 2048 @xmath8 4608 pixels , which works in both imaging and spectroscopy modes .
each pixel of the yfosc corresponds to the sky angle @xmath9 .
the spectra were taken with two gratings , g8 and g3 .
the dispersions of g8 and g3 are 1.5 @xmath10 and 2.9 @xmath10 , respectively .
the wavelength coverage is about 4970 - 9830   and 3200 - 9200   for g8 and g3 , respectively .
the details of observations are listed in table  [ tab1 ] .
0.1pt 0.5pt    ccccccc source name & date & exp .
( s ) & slit ( @xmath11 ) & grim & @xmath2 range (  ) & res .
(  ) + & 2014/11/25 & 2400 & 1.8 & g3 & 4264 - 8603 & 16 + & 2015/03/13 & 3000 & 2.5 & g3 & 3892 - 9110 & 20 + & 2015/03/16 & 3000 & 2.5 & g3 & 4156 - 9109 & 20 + & 2014/05/30 & 2400 & 1.8 & g8 & 5182 - 9518 & 8 +    the spectra are reduced with the standard iraf routines , including the bias substraction , flat field corrections and the removal of cosmic rays .
wavelength calibration is performed with the neon and helium lamps .
the spectra are flux calibrated with the spectrophotometric flux of standard stars observed at a similar air mass on the same night .
the spectral resolution is estimated using the fwhm of the sky emission lines ( table  [ tab1 ] ) .
the four reduced 1-d spectra are plotted in figure  [ fig1 ] .
the galactic extinction is firstly corrected using the dust map from @xcite and the extinction curve from @xcite with @xmath12 = 3.1 .
then we fit the four spectra in the rest frame .
the pseudo - continuum are decomposed with a power - law agn continuum , a host galaxy component ( for the optical band in the rest frame ) , and a fe ii template .
the fitting algorithm is followed hu et al .
@xcite ( also see @xcite ) .
the emission lines are fitted with gaussian profiles or gauss - hermite function . throughout this paper ,
we just focus on the h@xmath0 and mg ii region .
the h@xmath0 and mg ii are treated as a broad component plus a narrow one .
if one single gaussian can not fit the broad component well , we model it with a gauss - hermite function ( for ) . each of [ o iii ] doublet
is fitted with one gaussian . for , two gaussian profiles are performed to model the unusual [ o iii ] .
then the fitted fwhm is corrected for the instrumental broaden listed in table [ tab1 ] .
the strength of optical fe ii is represented by fe ii @xmath24570 ( integrated between @xmath24434 and @xmath24684 ) .
the ultraviolet ( uv ) fe ii is integrated in the range 2200 - 3090  .
the details of each sources are discussed below .    * * .
this source encounter a low signal / noise ratio ( s / n ) .
however , the mg ii and c iii lines are prominent ( upper left panel in figure [ fig1 ] ) .
the spectrum in rest frame which is corrected the galactic extinction around mg ii is plotted in figure [ fig2 ] , along with the modeled components . the flux and fwhm of the broad mg ii are @xmath13 and @xmath14 , respectively .
the flux of fe ii is @xmath15 .        * * .
@xcite labelled this sources as a low - luminosity css source .
@xcite noted that the optical image showed weak extended emission .
the optical spectrum manifests a large contribution of host galaxy component ( figure [ fig3 ] ) .
we obtain the flux and fwhm of the broad h@xmath0 which are @xmath16 and @xmath17 , respectively .
the [ o iii]@xmath25007/h@xmath0 and fe ii / h@xmath0 ( the so called r4570 parameter ) are 1.59 and 0.8 , respectively .    * * .
this is a famous ulirg with high velocity outflows observed at optical and x - ray band @xcite .
@xcite labelled this sources as a radio - loud nls1 and presented that its radio feature was compact and steep spectrum .
the optical spectrum of show large intrinsic extinction @xcite .
thus a intrinsic extinction @xmath18 mag is corrected to make the balmer decrement close to 3.1 @xcite .
the peak of [ o iii ] has a blueshift about 700 km s@xmath19 relative to the peak of h@xmath0 .
the h@xmath0 can be well fitted with a gauss - hermite function .
thus we treat total h@xmath0 as a broad component , while the narrow component of h@xmath0 is too weak to model .
the central wavelengths of the two gaussians also have systematic offsets with that of [ o iii ] . ]
( figure [ fig4 ] ) .
the fwhm of broad h@xmath0 is @xmath20 , which is slightly larger than @xmath21 listed in @xcite .
the flux of broad h@xmath0 is @xmath22 .
the [ o iii]@xmath25007/h@xmath0 and fe ii / h@xmath0 are 0.80 and 1.58 , respectively .    * * .
( pks 1345 + 12 ) is hosted in a major merger system which is still ongoing @xcite .
the gps nuclei was classified as a narrow line radio galaxy ( nlrg ) by @xcite .
however , it has very broad [ o iii ] lines .
the broad [ o iii ] can be fitted by two gaussian profiles ( figure [ fig5 ] ) .
recent analysis of its sdss spectrum showed a broad h@xmath0 component @xcite .
our results show that the broad h@xmath0 has the same blueshift ( about 1549 km s@xmath19 ) with the blueshifted [ o iii ] doublet .
and its fwhm ( 2130 km s@xmath19 ) is also consistent with the blue wing of [ o iii ] .
thus the detected broad h@xmath0 corresponds to the blue shifted narrow line component , but not originates from broad line region ( blr ) .
we estimate the black hole mass of three type 1 sources . the calculations
for h@xmath0 follow the relation of single epoch reverberation mapping in @xcite , @xmath23 for mg ii , we use the relation in @xcite , @xmath24 then we estimate the eddington ratio @xmath25 @xcite . the results are listed in table [ tab2 ] .
0.1pt 0.5pt    cccccc source name & redshift & @xmath26 ( @xmath27 ) & log@xmath28 & @xmath29 + & 1.62 & @xmath30 & 8.88 & 0.23 + & 0.208 & @xmath31 & 7.66 & 0.10 + & 0.189 & @xmath32 & 7.63 & 2.45 + & 0.122 &  & 7.82 & 0.27 +    the estimated average values of eddiongton ratios for nls1s are from 0.15 @xcite to 0.79 @xcite , while the broad line seyfert 1 galaxies ( bls1 ) have the average value about 0.16 @xcite . the eddington ratios of four young radio sources are generally larger than bls1 and distributes in the range of nls1s .
the three type 1 sources all show strong fe ii emissions , and [ o iii ] emission is weak for and .
these features confirm that the emission lines properties of young radio sources are similar with nls1s , except that the line width of young radio sources is broader than that of nls1s .
the estimated black hole mass is also larger than the average value of nls1s @xcite .
meanwhile , the radio powers of the compact steep - spectrum nls1s are at the low end of that of young radio sources @xcite , but locate in the range of the low - luminosity compact radio sources ( @xmath33 , @xcite ) .
therefore , we suggest the young radio sources are the high mass counterparts of the steep - spectrum radio - loud nls1s .
the blue wing of [ o iii ] is a prominent feature in nls1s @xcite . among the four sources ,
the blue wings of [ o iii ] are presented in and .
both sources are ulirgs , and with relatively high eddiongton ratio , which links the outflow mechanism to high star formation rate or high accretion rate .
we acknowledge the support of the staff of the lijiang 2.4 m telescope .
funding for the telescope has been provided by cas and the people s government of yunnan province .
this research is supported by the strategic priority research program of the chinese academy of sciences - the emergence of cosmological structures ( grant no .
xdb09000000 ) , the key research program of the chinese academy of sciences ( grant no .
kjzd - ew - m06 ) , and the nsfc through nsfc-11133006 and 11361140347 .
we report the optical spectroscopy of four young radio sources which are observed with the lijiang 2.4 m telescope 
 . the eddington ratios of these sources are similar with those of narrow - line seyfert 1 galaxies ( nls1s ) . 
 their fe ii emission is strong while [ o iii ] strength is weak . 
 these results confirm the nls1 features of young radio sources , except that the width of broad h@xmath0 of young radio sources is larger than that of nls1s . 
 we thus suggest that the young radio sources are the high black hole mass counterparts of steep - spectrum radio - loud nls1s . 
 in addition , the broad h@xmath0 component of is the blue wing of the narrow component , but not from the broad line region .    
 galaxies : jets  quasars : emission lines  quasars : individual ( , , , )