Stringent upper limits to the mass-loss rate of the Type Ia SN 2021hiz from e-MERLIN radio observations

ATel #14595; M. Perez-Torres (IAA-CSIC, Granada), J. Moldon (IAA-CSIC, Granada; JBCA, Manchester), P. Lundqvist (Stockholm University), D. Venkattu (Stockholm University), on behalf of a larger collaboration.
on 3 May 2021; 12:44 UT
Credential Certification: Miguel A. Perez-Torres (torres@iaa.es)

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We report the non-detection at radio wavelengths of the Type Ia SN 2021hiz, discovered on 2021-03-30 08:36:49.003 UT at the position RA(J2000.0)=12:25:41.675, DEC(J2000.0)=+07:13:42.26 (ATel #14500). SN 2021hiz exploded in the galaxy IC 3322A (z=0.0033; D=19 Mpc), and was identified with a Type Ia SN about 15 days before its maximum light (ATel #14500).

We observed SN 2021hiz on 2021-04-07 UT and 2021-04-08 UT, in both occasions from 00:10 till 04:50 UT, using the electronic Multi-Element Radio Linked Interferometer Network (e-MERLIN), including the Lovell telescope. We observed SN 2021hiz at a central frequency of 5.1 GHz, using a bandwidth of 512 MHz, and obtained an angular resolution of about 50 milliarcseconds. We found no evidence of radio emission in a circular region of about 5.0 arcsec in radius surrounding SN 2021hiz in either epoch, above a 3-sigma upper limit of 63 and 75 microJy/beam, respectively, which correspond to upper limits to the monochromatic luminosity of 2.7E25 and 3.2E25 erg/s. Assuming that SN 2021hiz exploded on March 27.0 UT, our radio observations were then carried out 11 and 12 days after the explosion.

For our standard model with a presupernova wind speed of 100 km/s (see ATels #11324, #12411, #14325) the above limits to the radio luminosity correspond to upper limits of 3.0E-8 and 3.6E-8 solar masses per year for the mass-loss rate on May 7 and May 8, 2021. The stacked data yielded a 3-sigma upper limit of 16 microJy/beam (radio luminosity limit of 2.1E25 erg/s), which results in a mass-loss rate upper limit of 2.5E-8 solar masses per year. Those upper limits to the mass-loss rate of SN 2021hiz are among the most stringent upper limits found for type Ia SNe, especially in view of the distance to the host galaxy, showing the importance of probing the radio emission from type Ia SNe within a radius of about 25 Mpc.

e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC.