Radio constraints on the mass-loss rate of the Type Ia SN 2019np
ATel #12411; M. Perez-Torres (IAA-CSIC, Granada), P. Lundqvist (Stockholm University), J. Moldon (JBCA, Manchester), E. Kundu (Stockholm University), R. Beswick (JBCA, Manchester), E. Varenius (JBCA, Manchester), A. Alberdi (IAA-CSIC, Granada), S. Ryder (Macquarie University/AAO), C.-I. Bjornsson (Stockholm University), C. Fransson (Stockholm University), A. Horesh (Tel Aviv University)
on 20 Jan 2019; 21:48 UT
Credential Certification: Miguel A. Perez-Torres (torres@iaa.es)
Subjects: Radio, Supernovae, Transient
We observed the young Type Ia supernova 2019np with the electronic Multi-Element Radio Linked Interferometer Network (e-MERLIN) at 5.1 GHz. SN2019np was discovered on 9.67 January 2019 UT in the nearby (z=0.00452) galaxy NGC3254 (Itagaki, TNS discovery report #28550), and a spectrum on 10.83 February 2019 confirmed the SN as a Type Ia event two weeks before maximum (Burke, TNS classification report #3399).
Our e-MERLIN observations were carried out between 14.81 and 15.46 January 2019 UT, five days after the SN discovery, i.e. roughly 10 days after the SN explosion. We observed at a central frequency of 1.51 GHz, with a bandwidth of 512 MHz, and centered our observations at the position of the optical discovery (J2000.0 coordinates RA=10:29:21.960, DEC=+29.30.38.40). We find no evidence of radio emission in a circular region of 5.0 arcsec of radius surrounding SN2019np, down to a 3-sigma upper limit of 66 microJy/beam. For an assumed distance of 22 Mpc, the corresponding upper limit of the monochromatic 1.51 GHz luminosity is of 3.82E25 erg/s/Hz (3-sigma). Using the same model as in ATels #10168, #11211, and #11324 for SN 2016coj, SN2018gv and SN2018pv, respectively, and assuming optically thin radio emission for SN2019np, we place a limit on the mass loss rate of the supernova progenitor of 1.7E-8 solar masses per year (3-sigma), for an assumed wind speed of 100 km/s. We thank the e-MERLIN staff for supporting our ToO program in search for radio emission from Type Ia supernovae, and encourage observations at other frequencies to further constrain the mass loss rate of SN2019np.