J/MNRAS/448/1206 Superluminous supernovae in faint galaxies (McCrum+, 2015) ================================================================================ Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey. McCrum M., Smartt S.J., Rest A., Smith K., Kotak R., Rodney S.A., Young D.R., Chornock R., Berger E., Foley R.J., Fraser M., Wright D., Scolnic D., Tonry J.L., Urata Y., Huang K., Pastorello A., Botticella M.T., Valenti S., Mattila S., Kankare E., Farrow D.J., Huber M.E., Stubbs C.W., Kirshner R.P., Bresolin F., Burgett W.S., Chambers K.C., Draper P.W., Flewelling H., Jedicke R., Kaiser N., Magnier E.A., Metcalfe N., Morgan J.S., Price P.A., Sweeney W., Wainscoat R.J., Waters C. =2015MNRAS.448.1206M (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Galaxies, nearby ; Supernovae ; Photometry Keywords: supernovae: general - supernovae: individual: PS1-10pm - supernovae: individual: PS1-10ahf Abstract: The Pan-STARRS1 (PS1) survey has obtained imaging in five bands (griz y_P1_) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of M_AB_~23.5, of which 76 were classified as Type Ia supernovae (SNe Ia). There were 57 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or type Ic SLSNe and 12 of these have had spectra taken. Of these 12 hostless, non-Type Ia SNe, 7 were SLSNe of type Ic at redshifts between 0.5 and 1.4. This illustrates that the discovery rate of type Ic SLSNe can be maximized by concentrating on hostless transients and removing normal SNe Ia. We present data for two possible SLSNe; PS1-10pm (z=1.206) and PS1-10ahf (z=1.1), and estimate the rate of type Ic SLSNe to be between 3^+3^_-2_x10^-5^ and 8^+2^_-1_x10^-5^ that of the CCSN rate within 0.3<=z<=1.4 by applying a Monte Carlo technique. The rate of slowly evolving, type Ic SLSNe (such as SN2007bi) is estimated as a factor of 10 lower than this range. Description: From the period starting February 25th 2010 and ending July 9th 2011, 249 hostless transients or "orphans" were discovered in the PS1 Medium Deep fields. AN orphan is defined as an object that is >3.4" away from the centre of a catalogued galaxy or point source brighter than approximately 23.5m (in any of the g_P1_ r_P1_ i_P1_ filters that the transient was detected in). The PS1 observations are obtained through a set of five broadband filters, which we have designated as g_P1_, r_P1_, i_P1_, z_P1_, and y_P1_. Although the filter system for PS1 has much in common with that used in previous surveys, such as SDSS (Abazajian et al., 2009ApJS..182..543A), there are important differences. The gP1 filter extends 20nm redward of g_SDSS_, paying the price of 5577{AA} emission for greater sensitivity and lower systematics for photometric redshifts, and the zP1 filter is cut off at 930nm, giving it a different response than the detector response which defined z_SDSS_. SDSS has no corresponding y_P1_ filter. Further information on the passband shapes is described in Stubbs et al. (2010ApJS..191..376S). The PS1 photometric system and its response is covered in detailed in Tonry et al. (2012ApJ...750...99T, Cat. J/ApJ/750/99). Photometry is in the "natural" PS1 system, m=-2.5log(flux)+m', with a single zeropoint adjustment m' made in each band to conform to the AB magnitude scale. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table3.dat 112 28 The 28 spectroscopically confirmed PS1 SN Ia table4.dat 71 48 The 48 plausible PS1 SN Ia, classified using the soft and psnid photometric classification codes table5.dat 109 12 *The 12 confirmed PS1 CCSNe table6.dat 63 17 *The 17 plausible PS1 CCSNe table7.dat 136 75 Observed photometry for PS1-10pm table10.dat 105 64 Observed photometry for PS1-10ahf tablea2.dat 67 28 The 28 SN-like orphans tablea3.dat 53 116 The 116 unknown orphans -------------------------------------------------------------------------------- Note on table5.dat: Of note is the high percentage of SLSNe Ic confirmed. Note on table6.dat: The values in the soft and psnid columns represent the probability that the object is classified as the type II subclass listed. -------------------------------------------------------------------------------- See also: J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012) Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Field Field 6- 16 A11 --- Name Supernova PS1 designation (PS1-NNAAA or PS1-NNNNNNN) 17 A1 --- n_Name [*] Note on Name (1) 19- 26 F8.4 deg RAdeg Right ascension (J2000) 28- 34 F7.4 deg DEdeg Declination (J2000) 36- 40 F5.3 --- zsp Spectroscopic redshift 42- 47 F6.3 mag rP1mag Peak rP1 magnitude 49- 53 F5.3 mag e_rP1mag rms uncertainty on peak rP1 magnitude 55- 62 A8 --- Tel Telescope 64- 73 A10 "date" Date Observation date 75 A1 --- Note [*] Note for spectral classification (2) 77-112 A36 --- Ref References -------------------------------------------------------------------------------- Note (1): The MD06 object PS1-11acn is designated as PTF11dws in the cited source of classification. Note (2): * = spectral classifications for these objects as SNe Ia can be found in Rest et al. (2014ApJ...795...44R) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Field Field 6- 16 A11 --- Name Supernova PS1 designation (PS1-NNAAA) 18- 25 F8.4 deg RAdeg Right ascension (J2000) 27- 34 F8.4 deg DEdeg Declination (J2000) 36- 40 F5.3 --- soft ?=- Probability that the object is classified as an SN Ia with soft photometric classification code (G1) 42- 46 F5.3 --- psnid ?=- Probability that the object is classified as an SN Ia with psnid photometric classification code (G1) 48- 52 F5.3 --- zph ?=- Photometric redshift 54- 58 F5.3 --- e_zph ?=- rms uncertainty on zph 60- 65 F6.3 mag rP1mag ?=- Peak rP1 magnitude 67- 71 F5.3 mag e_rP1mag ? rms uncertainty on peak rP1 magnitude -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Field Field 6- 16 A11 --- Name Supernova PS1 designation (PS1-NNAAA) 17 A1 --- n_Name [a*] Note on Name (1) 19- 26 F8.4 deg RAdeg Right ascension (J2000) 28- 35 F8.4 deg DEdeg Declination (J2000) 37- 48 A12 --- Type Type 50- 54 F5.3 --- zsp Spectroscopic redshift 57- 61 F5.3 --- soft ?=- Probability that the object is classified as the SNe type given in Typesoft column (soft photometric classification code) (G1) 63- 65 A3 --- Typesoft Type from soft 67- 71 F5.3 --- psnid ?=- Probability that the object is classified as the SNe type given in Typepsnid column (psnid photometric classification code) (G1) 73- 75 A3 --- Typepsnid Type from psnid 77- 82 F6.3 mag rP1mag ?=- Peak rP1 magnitude 84- 88 F5.3 mag e_rP1mag ? rms uncertainty on peak rP1 magnitude 90- 92 A3 --- Inst Instrument 94-103 A10 "date" Date Observation date 105-109 A5 --- Ref Reference(s) (2) -------------------------------------------------------------------------------- Note (1): Notes as follows: * = the two objects are explored further in this paper. a = PS1-10afx has been shown to be a lensed SN Ia, and is included here for completeness of objects, although we do not use it in any of our rate estimates Note (2): References as follows: 1 = McCrum et al. (2014MNRAS.437..656M) 2 = this paper 3 = Lunnan et al. (2014ApJ...787..138L) 4 = Chomiuk et al. (2011ApJ...743..114C) 5 = Chornock et al. (2013ApJ...767..162C) 6 = Quimby et al. (2013MNRAS.431..912Q, 2013ApJ...768L..20Q) 7 = Quimby et al. (2014Sci...344..396Q) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table6.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Field Field 6- 16 A11 --- Name Supernova PS1 designation (PS1-NNAAA) 18- 25 F8.4 deg RAdeg Right ascension (J2000) 27- 34 F8.4 deg DEdeg Declination (J2000) 36- 38 A3 --- Type Type 40- 44 F5.3 --- soft ?=- Probability that the object is classified as the type II subclass listed with soft photometric classification code (G1) 46- 50 F5.3 --- psnid ?=- Probability that the object is classified as the type II subclass listed with psnid photometric classification code (G1) 52- 57 F6.3 mag rP1mag ?=- Peak rP1 magnitude 59- 63 F5.3 mag e_rP1mag ? rms uncertainty on peak rP1 magnitude -------------------------------------------------------------------------------- Byte-by-byte Description of file: table7.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 "date" Date Observation date 12- 19 F8.2 d MJD Modified Julian date 21- 27 F7.2 d Phase Phase, in observer frame, not rest frame 29 A1 --- l_gP1mag Limit flag on gP1mag 30- 34 F5.2 mag gP1mag ?=- gP1 (481nm) magnitude (1) 36- 39 F4.2 mag e_gP1mag ? rms uncertainty on gP1mag 42 A1 --- l_rP1mag Limit flag on rP1mag 43- 47 F5.2 mag rP1mag ?=- rP1 (617nm) magnitude (1) 49- 52 F4.2 mag e_rP1mag ? rms uncertainty on rP1mag 55 A1 --- l_iP1mag Limit flag on iP1mag 56- 60 F5.2 mag iP1mag ?=- iP1 (752nm) magnitude (1) 62- 65 F4.2 mag e_iP1mag ? rms uncertainty on iP1mag 68 A1 --- l_zP1mag Limit flag on zP1mag 69- 73 F5.2 mag zP1mag ?=- zP1 (866nm) magnitude (1) 75- 78 F4.2 mag e_zP1mag ? rms uncertainty on zP1mag 82- 86 F5.2 mag gmag ?=- g magnitude (1) 88- 91 F4.2 mag e_gmag ? rms uncertainty on gmag 95- 99 F5.2 mag rmag ?=- r magnitude (1) 101-104 F4.2 mag e_rmag ? rms uncertainty on rmag 108-112 F5.2 mag imag ?=- i magnitude (1) 114-117 F4.2 mag e_imag ? rms uncertainty on imag 121-125 F5.2 mag zmag ?=- z magnitude (1) 127-130 F4.2 mag e_zmag ? rms uncertainty on zmag 134-136 A3 --- Tel Telescope -------------------------------------------------------------------------------- Note (1): No K-corrections have been applied. Note that the PS1 observations have had any flux from a previous reference image removed through image subtraction (although note that no host object can be seen at the location of PS1-10pm) whereas the late time WHT and GN observations have not. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table10.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 "date" Date Observation date 12- 19 F8.2 d MJD Modified Julian date 21- 27 F7.2 d Phase Phase, in observer frame, not rest frame, as more than one possible redshift value is presented in the text 29 A1 --- l_rP1mag Limit flag on rP1mag 30- 34 F5.2 mag rP1mag ?=- rP1 (617nm) magnitude (1) 36- 39 F4.2 mag e_rP1mag ? rms uncertainty on rP1mag 41 A1 --- l_iP1mag Limit flag on iP1mag 42- 46 F5.2 mag iP1mag ?=- iP1 (752nm) magnitude (1) 48- 51 F4.2 mag e_iP1mag ? rms uncertainty on iP1mag 53 A1 --- l_zP1mag Limit flag on zP1mag 54- 58 F5.2 mag zP1mag ?=- zP1 (866nm) magnitude (1) 60- 63 F4.2 mag e_zP1mag ? rms uncertainty on zP1mag 66- 70 F5.2 mag rmag ?=- r magnitude (1) 72- 75 F4.2 mag e_rmag ? rms uncertainty on rmag 78- 82 F5.2 mag imag ?=- i magnitude (1) 84- 87 F4.2 mag e_imag ? rms uncertainty on imag 91- 95 F5.2 mag zmag ? z magnitude (1) 97-100 F4.2 mag e_zmag ? rms uncertainty on zmag 103-105 A3 --- Tel Telescope -------------------------------------------------------------------------------- Note (1): No K-corrections have been applied. Note that the PS1 observations have had any flux from previous reference image removed through image subtraction (although note that no host object can be seen at the location of PS1-10ahf) whereas the late time WHT and GS observations have not. -------------------------------------------------------------------------------- Byte-by-byte Description of file: tablea2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Field Field 6- 16 A11 --- Name Supernova PS1 designation (PS1-NNAAA) 18- 25 F8.4 deg RAdeg Right ascension (J2000) 27- 34 F8.4 deg DEdeg Declination (J2000) 36- 40 F5.3 --- soft ?=- Probability that the object is classified as the SNe type given in Typesoft column (soft photometric classification code) (G1) 42- 44 A3 --- Typesoft Type from soft (2) 46- 50 F5.3 --- psnid ?=- Probability that the object is classified as the SNe type given in Typepsnid column (psnid photometric classification code) (G1) 52- 54 A3 --- Typepsnid Type from psnid (2) 56- 61 F6.3 mag rP1mag ?=- Peak rP1 magnitude 63- 67 F5.3 mag e_rP1mag ? rms uncertainty on peak rP1 magnitude -------------------------------------------------------------------------------- Note (2): none of these objects met with the confidence restrictions placed upon the photometric classifiers for identifying SNe (see Tables 4 and 6 for objects that do), it can be seen here that a large number of these objects were given some sort of tentative, photometric SNe classification. -------------------------------------------------------------------------------- Byte-by-byte Description of file: tablea3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Field Field 6- 16 A11 --- Name Supernova PS1 designation (PS1-NNAAA) 18- 25 F8.4 deg RAdeg Right ascension (J2000) 27- 34 F8.4 deg DEdeg Declination (J2000) 36- 41 F6.3 mag rP1mag ?=- Peak rP1 magnitude 43- 47 F5.3 mag e_rP1mag ? rms uncertainty on peak rP1 magnitude 49- 53 A5 --- LC LC Status (1) -------------------------------------------------------------------------------- Note (1): LC Status as follows: INC = objects have incomplete light curves VAR = objects have variable light curves with no obvious trend FAINT = objects fall out of the magnitude range for spectroscopic or reliable photometric classification RED = no detections in the g_P1_- or r_P1_-band filters but showed a faint peak in the i_P1_- and z_P1_-band filters, possibly as a result of a single, energetic outburst such as an SN at high redshift -------------------------------------------------------------------------------- Global notes: Note (G1): soft and psnid photometric classification codes (Sako et al., 2008AJ....135..348S, Cat. J/AJ/135/348, 2011ApJ...738..162S, Cat. J/ApJ/738/162; Rodney & Tonry 2009ApJ...707.1064R). -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 04-Sep-2015