We present IRAM/NOEMA and JVLA observations of the quasar J1342+0928 at z = 7.54 and report detections of copious amounts of dust and [ \ion C2 ] emission in the interstellar medium ( ISM ) of its host galaxy .
At this redshift , the age of the universe is 690 Myr , about 10 % younger than the redshift of the previous quasar record holder .
Yet , the ISM of this new quasar host galaxy is significantly enriched by metals , as evidenced by the detection of the [ \ion C2 ] 158 \mu m cooling line and the underlying far-infrared ( FIR ) dust continuum emission .
To the first order , the FIR properties of this quasar host are similar to those found at a slightly lower redshift ( z \sim 6 ) , making this source by far the FIR-brightest galaxy known at z \gtrsim 7.5 .
The [ \ion C2 ] emission is spatially unresolved , with an upper limit on the diameter of 7 kpc .
Together with the measured FWHM of the [ \ion C2 ] line , this yields a dynamical mass of the host of < 1.5 \times 10 ^ { 11 } M _ { \sun } .
Using standard assumptions about the dust temperature and emissivity , the NOEMA measurements give a dust mass of ( 0.6 - 4.3 ) \times 10 ^ { 8 } M _ { \sun } .
The brightness of the [ \ion C2 ] luminosity , together with the high dust mass , imply active ongoing star formation in the quasar host .
Using [ \ion C2 ] –SFR scaling relations , we derive star formation rates of 85–545 M _ { \sun } yr ^ { -1 } in the host , consistent with the values derived from the dust continuum .
Indeed , an episode of such past high star formation is needed to explain the presence of \sim 10 ^ { 8 } M _ { \sun } of dust implied by the observations .