Download This Article in PDF Format

Home , Leo I (dwarf galaxy), Leo Triplet, List of ring galaxies

A&A 615, A105 (2018) Astronomy https://doi.org/10.1051/0004-6361/201832897 & © ESO 2018 Astrophysics

The Leo-I group: new dwarf galaxy and ultra diffuse galaxy candidates Oliver Müller1, Helmut Jerjen2, and Bruno Binggeli1

1 Departement Physik, Universität Basel, Klingelbergstr. 82, 4056 Basel, Switzerland e-mail: [email protected] 2 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia

Received 23 February 2018 / Accepted 21 March 2018

ABSTRACT

Context. The study of dwarf galaxies and their environments provides crucial test beds for predictions of cosmological models and insights into the structure formation on small cosmological scales. In recent years, many problems on the scale of groups of galaxies has challenged the current standard model of cosmology. Aims. Our aim is to increase the sample of known galaxies in the Leo-I group, which contains the M 96 subgroup and the Leo Triplet. This galaxy aggregate is located at the edge of the Local Volume at a mean distance of 10.7 Mpc. Methods. We employed image enhancing techniques to search for low surface brightness objects in publicly available gr images taken by the Sloan Digital Sky Survey within 500 square degrees around the Leo-I group. Once detected, we performed surface photometry and compared their structural parameters to other known dwarf galaxies in the nearby universe. Results. We found 36 new dwarf galaxy candidates within the search area. Their morphology and structural parameters resemble known dwarfs in other groups. Among the candidates five or six galaxies are considered as ultra diffuse galaxy candidates. If confirmed, they would be some of the closest examples of this galaxy type. We assessed the luminosity function of the Leo-I group and find it to be considerably rich in dwarf galaxies, with twice the number of galaxies as the Local Group at a limiting magnitude of MV = 10 and a steeper faint-end slope. − Key words. galaxies: groups: individual: Leo-I – galaxies: dwarf – galaxies: photometry – galaxies: luminosity function, mass function

1. Introduction et al. 2016, 2018) or the TBTF and missing satellite problems in M 101 (Danieli et al. 2017; Müller et al. 2017b). More than one thousand galaxies reside in a sphere of 11 Mpc Using public data from the Sloan Digital Sky Survey (SDSS) radius around the Milky Way; they are mostly dwarf-type we have started to systematically search for new or hitherto galaxies (MB > 17.7 mag). This so-called Local Volume undetected dwarf galaxies in the Local Volume, beginning with (Kraan-Korteweg &− Tammann 1979; Karachentsev et al. 2004, the M 101 group complex, covering 330 deg2 around the spiral 2013) contains many prominent galaxy aggregates, e.g., our galaxies M 101, M 51, and M 63. We found 15 new dwarf galaxy own Local Group (LG), the Sculptor ﬁlament, the Centaurus candidates (Müller et al. 2017b). We now continue our optical group, the M 81 group, the Canes Venatici cloud, the M 101 search for dwarf galaxies in an area that covers 500 deg2 around group complex, and the Leo-I group (Tully & Fisher 1988). In the Leo-I group (Fig.1). recent years many teams have taken up the challenge to search The Leo-I group, with a mean distance of 10.7 Mpc for new dwarf galaxies in the local universe and measure their (Karachentsev et al. 2004, 2013), consists of seven bright distances (Chiboucas et al. 2009, 2013; Merritt et al. 2014; galaxies, NGC 3351 (=M 95), NGC 3368 (=M 96), NGC 3377, Belokurov et al. 2014; Crnojevic´ et al. 2014, 2016; Kim et al. NGC 3379 (=M 105), NGC 3384, NGC 3412, and NGC 3489 2015; Müller et al. 2015, 2017a,b; Carlin et al. 2016; Javanmardi (Karachentsev & Karachentseva 2004). Another four bright et al. 2016; Danieli et al. 2017; Carrillo et al. 2017; Henkel galaxies, NGC 3632 (=M 65), NGC 3627 (=M 66), NGC 3628 et al. 2017; Park et al. 2017; Makarova et al. 2018). These (which make up the Leo Triplet, about six degrees to the east studies can be used to test the theoretical predictions from the of the main aggregate), and NGC 3593, are possibly also part of standard model of cosmology (ΛCDM). For the LG, there is the group based on their common distances and systemic veloc- a serious tension between observation and theory represented ities (Ferrarese et al. 2000). We note that about eight degrees to by the long-standing missing satellite problem (Moore et al. the northeast is another quartet of bright galaxies (NGC 3599, 1999), the too-big-too-fail (TBTF) problem (Kroupa et al. 2010; NGC 3605, NGC 3607, and NGC 3608), which shares the same Boylan-Kolchin et al. 2011), and the plane-of-satellites problem systemic velocity but is farther behind and is arguably not (Kroupa et al. 2005; Pawlowski et al. 2012; Ibata et al. 2013; associated with the group (Ferrarese et al. 2000). Pawlowski 2018), see Bullock & Boylan-Kolchin(2017) for a A spectacular feature of the Leo-I group in HI is known recent review on small-scale challenges. Such studies are now as the Leo ring (Schneider 1985) around NGC 3384/M 105, extended to other nearby galaxy groups, for example to address one of the largest HI structures in the nearby universe. the plane-of-satellite problem in Cen A (Tully et al. 2015; Müller Michel-Dansac et al.(2010) followed this up with a deep optical

Article published by EDP Sciences A105, page 1 of 13 Oliver Müller et al.: The Leo-I group: new dwarf galaxy and UDG candidates

A&A 615, A105 (2018)

20 CVn 18

[deg] Leo-Tr 12 M96 10

4 12:00:00 11:00:00 10:00:00 [hr:mm:ss]

Fig. 1. SurveySurvey area area of of 500500 degdeg22inin the the Leo-I Leo-I group group region. region. The The squares squares correspond correspond to to the the created created 1 1 deg deg2 2mosaics.mosaics. The The small small black black dots dots are are Fig. 1. ≈ previouslypreviously known known members members≈ based based on on their their photometric photometric properties, properties, compiled compiled from from the the Local Local Volume Volume Catalog Catalog (Karachentsev (Karachentsev et et al. al. 2004, 2004 2013)., 2013). The The largelarge gray gray dots dots are are the the major major galaxies galaxies in in the the M M 96 96 subgroup subgroup and and Leo Leo Triplet. Triplet. The The red red dots dots indicate indicate the the positions positions of of the the 36 36 new new dwarf dwarf candidates. candidates. OpenOpen circles circles are are conﬁrmed conﬁrmed foreground foreground galaxies galaxies ( (<7<7 Mpc) Mpc) taken taken from from the the LV LV Catalog. Catalog.

survey using MegaCam on the CFHT and found no diffuse stellar main galaxy aggregate around M 96, and the term Leo-Tripletff 4.1. Membership estimation 2 them into V-band magnitudes. UDGs typically have an e ective optical component down to 28 mag arcsec− surface brightness. radius(Leo-Tr) larger for than the aggregater > 1.5 around kpc and M a 66. central Both surface subgroups brightness together The standard approach for establishing membership based on e f f The authors suggest an origin based on a collision between fainterare called than theµ Leo-I> 24.0 group mag arcsec (see Fig.2 (van1). Dokkum et al. 2015). morphologicalNGC 3384 and properties M 105 using is to gas compare and dark the matter structural simulations parameters that In this workg we present a search− for unresolved dwarf galax- ofcan the explain candidates the structure with known of the dwarf ring, together galaxies with (e.g., the Jerjen absence et al. of ies using publicly available data from the Sloan Digital Sky 2 Dwarf galaxies can also2 be characterized by their color us- 2000;apparent Chiboucas light. Deeper et al. images 2009; Merritt (µV > 29.5 et al. mag 2014; arcsec Müller− ) taken et al. by ingSurvey the color-magnitude (SDSS) in 500 deg relation, covering (e.g., theLisker extended et al. 2008; Leo-I groupVen- 2017a,b).Watkins et If al. the(2014 objects) have fit not into yet the revealed ( µ e f f no– M optical), (re f counterpart f – M), (µ0 region. In Sect.2 we summarize our search strategy, and in h i hola et al. 2017). Here we compare the (g r)0 colors of the –ofM the), and ring; (n however,– M) scaling they relations found some defined stream-like by the known features dwarf asso- Leo-ISect.3 group we present dwarfswith the surface other well-studied photometry− systems performed in the for LV all galaxiesciated with in the the local ring Universe, that are possibly it is reasonable of tidal origin. to consider In the them Leo whereknowngr andphotometry newly found is available, members namely of the Leo-I the Centaurus group. In group Sect.4 asTriplet dwarf another galaxy candidates.intriguing feature, The ( µ thise f f time– M) in and the (µ optical,0 – M) areis a we discuss our candidate list and potential background contam- h i (Müller et al. 2015, 2017a) and the M101 group complex (Müller especiallystellar stream crucial associated because with the the surface boxy brightness spiral NGC is 3628 independent (Zwicky ination. Finally, in Sect.5 we draw our conclusions and give a et al. 2017b). The calculated mean (g r)0 color and standard of1956 the), assumed which hosts distance a tidal of dwarf the object, galaxy therefore (Nikiel-Wroczy makingnski´ it pos- et al. brief outlook. − deviation for the three group populations are (g r)0,Leo I = sible2014) to and assess an ultra the membership compact dwarf at a galaxy certain (Jennings distance et (see al. Müller2015). − − 0.491 0.282 mag, (g r)0,Cen A = 0.463 0.258 mag, and et al.For 2017a, the Fig.central 11 forpart what of the happens Leo-I to group galaxies (i.e., with the unreason- M 96 sub- ± − ± (g2. Discoveryr)0,M 101 = 0 of.472 new0. dwarf190 mag. galaxy In Fig. candidates 6 we show the color ablegroup) distance an initial estimates catalog in those of 50 relations). dwarf galaxy To transform candidates our wasgr distribution− as a function± of total absolute V-magnitude for these photometryproduced by to Ferguson the Johnson & Sandage system we(1990 used). The thefollowing authors argued, equa- diInfferent recent groups. years, The different dwarfs automatic in the diff detectionerent galaxy approaches groups fol-have tionsbased (Lupton on morphological 2005): properties, that half of them are group lowbeen a proposed similar distribution to search for in low their surface colors. brightness We note galaxies that the (e.g., ex- members. Another collection of dwarf galaxies was discovered tremeMerritt blue et colors al. 2014 (g; Spellerr < 0) & of Taylor someobjects, 2014; van which deris Burg uncom- et al. V = g 0.5784 (g r) 0.0038 2 by Trentham & Tully−(2002) who· surveyed− 0 − a 10 10 deg field mon2016 for; Bennet dwarf et galaxies, al. 2017− ) and with the encouraging scatter at the results. faint-end On the of other the partially covering the Leo-I group. Using the digitized× sky sur- hands, these pipelines were only applied on small areas of the B = r + 1.3130 (g r) + 0.2271 scale can arise2 from the photometric uncertainty. vey, Karachentsev & Karachentseva· −(20040 ) refined and extended sky (<10 deg ) and still have a considerable rate of false detec- Thethis structural list to 50 parameters likely members. of the newly For many found members dwarf candidates, HI veloc- tions,In the or following rely on a we large discuss number some of individual existing galaxies candidates to study that andities of were the previously derived (Stierwalt discovered et Leo-I al. 2009 members), making and it the possible Local havegalaxy interesting groups onfeatures. a statistical basis. It remains to be seen how Groupto distinguish dwarf population, between actual are plotted Leo-I in members Fig. 5. The and structural background pa- dw1037these methods+09: This perform candidate on large-field has several surveys knots within with areas and around of sev- rametersgalaxies of belonging the dwarf to candidates the more fall distant into Leo the relations cloud (see defined Fig. 1 by in theeral galaxy, hundred which of square could either degrees be andbright how giant time-consuming stars or globular the theTrentham Local Group & Tully dwarfs, 2002 thusfor the we difference can assume in that velocity the candidates space). A clusterstask of (GC). rejecting false-positives will be. We argue, as do other arevery indeed deep dwarf but spatially members limited of the image, Leo-I group. based Additionally, on amateur tele- we dw1110authors+ (e.g.,18: Here Park too et there al. 2017 are; several Wittmann knots et sprinkled al. 2017 through), that a showscopes, the was 44 UDG produced candidates for NGC in the 3628 Coma in the Cluster Leo Tripletdiscovered and thevisual object, search which on could images be bright is still giant on par stars with or GCs. algorithm-based byrevealed van Dokkum another et faint al. (2015), dwarf galaxy who only (Javanmardi gave g band et al. photometry 2016). dw1130detections.+20: This galaxy has some bright knots, which could and soTo we follow assume a aconsistent color index naming of (g conventionr) = 0.6 mag in to this transform paper, correspondIn this to work, HII regions. we follow the same methods as described in from now on we use the term M 96− subgroup to describe the Müller et al.(2017b) to search for dwarf galaxies in an area Article number, page 3 of 12 A105, page 2 of 13 O. Müller et al.: The Leo-IA& group:A proofs: newmanuscript dwarf galaxy no. and aanda UDG candidates

Fig. 2.Fig.Gallery 2. Gallery showing showing SDSS r-band SDSS imagesr-band of images the new of Leo-I the new group Leo-I member group candidates. member candidates. One side of Onean image side corresponds of an image to corresponds 80 arcsec or to 3.88 80 kpc arcsec or at the distance3.88 kpc of at 10the Mpc. distance North of is 10 to Mpc. the top, North east is to to the the right. top, east to the right. of 500 degUnder2 around the assumption the Leo-I that group all candidates using data are taken members from of thethe Leoa confusion Triplet, or is in the the massive surrounding elliptical field. galaxy In Fig. NGC2 we 5485 present with its the∼ SDSS.Leo-I In group, summary we can this determine involves the the galaxy creation luminosity of 1 square functionimagesmany of the dwarf newly companions discovered (Makarov candidates. & Karachentsev Some dwarf galaxy 2011) situ- (see Fig. 7) and compare it to other nearby galaxy group envi-candidatesated show20 Mpc irregularities. behind the LocalWe checked Volume the galaxy Galaxy M101 Evolu- (7 Mpc, degree mosaics of g and r images, the use of several image pro- ≈ cessingronments, algorithms i.e., (e.g., the Centaurus binning and group Gaussian (Müller convolution) et al. 2015, to2017a),tion ExplorerNataf 2015). (GALEX) Figure survey 8 in Merritt (in the et near- al. (2016) and far-ultraviolet) shows M 101, the enhancethe the LG low (McConnachie surface brightness 2012),features the M101 within group the (Bremnes images, etfor al. extendedbackground objects elliptical coinciding NGC with 5485, our and detections. former M Indeed, 101 dwarf the can- and the1999; final Müller visual et search al. 2017b), for dwarf and galaxies the NGC2784 in these group processed (Park etcandidates al. didates dw1013+18, (Merritt et dw1045+14a, al. 2014) that dw1049+15, actually belong dw1116+15b, to the back- images.2017). Once Among an object these is detected, five groups, surface the photometry Leo-I group is applied is the rich-dw1130+20,ground galaxyand dw1148+16 population. have Out some of the UV seven features, dwarf possi- candidates to deriveest galaxy the structural aggregate parameters, with approximately which are compared 100 galaxies to the up tobly an hintingreported towards by Merritt star formation. et al. (2014), These only objects three wereare classified confirmed to absolute magnitude of MV = 10, in other words if all candi-as dIrr/dSphbe M 101 if members they possess with a HST smooth follow-up profile observations and are likely (Danieli properties of known dwarf galaxies of− the LG and other groups. Baseddates on this are morphological confirmed as members.comparison, The a detection Leo-I group is consid- has approx-transitionet al. type 2017). dwarfs. Recently, more new dwarf candidates were reported ered orimately rejected twice as a as dwarf many galaxy dwarfs candidate. as the LG To and estimate a steeper our faint- around M 101 (Bennet et al. 2017; Müller et al. 2017b), now detectionend rateslope we of conducted the LF, comparable an experiment to that where of Cen we A. induced The M 101 awaiting confirmation as members by means of distance or ve- artificialand galaxies NGC 2784 into groups the SDSS have images shallower and derived faint-end the slopes. recovery This in-3. Surfacelocity measurements. photometry Some will potentially be associated with rate ofdicates these objects that galaxy (Fig. groups 3 in Müller with massive et al. 2017b hosts). have steeper faint- the background elliptical NGC 5485. Inends Fig.1 of we the present LF. While the survey the faint-end footprint, slopes the known of Leo-I galaxies and CenWe A computedThe possibility the total of apparent contamination magnitude promptedm, the us mean to study effective the back- are comparable, the Leo-I group contains more brighter galaxiessurfaceground brightness of the Leo-Iµ , andgroup the in effective more detail. radius In Müllerr in g etr bands al. (2017a) in this field (black and gray dots), and the new dwarf galaxy can- h ieff eff didatesin (red the range dots) from found -16 in to our -14 search. mag in InV-bands, the up-to-date making online it more richfor eachwe dwarfused the galaxy Cosmicflows-2 candidate, and catalog for already (Tully et known al. 2013) group to de- (up1 to M = 10). In this range (-16 to -14 V mag), the LFmembers of termine as many the background of them do contamination not have accurate of the Centaurusphotometry. group. version of theV LV− catalog, 63 dwarf galaxies are listed within our footprint,Leo-I is withcomparable four (open to that circle) of the having LG. a distance estimate To measureHere we the query surface the brightness Cosmicflows-2 profiles catalog we used for a bright circular galax- apertureies with(step absolute size of 0 magnitudes00. 396 correspondingMB<-19 to and 1 withpixel). radial Sérsic veloci- smaller than 7 Mpc. In Table A.1 we present the coordinates of 1 the 36 dwarf galaxy candidates found in the survey, together with profilesties (Sersicvrad<2000 1968 km) were s− within fitted our at the survey derived footprint. profiles Excluding using the our galaxy4.2. Background type classification contamination and comments on the objects. We the equationLeo-I galaxies this search resulted in 24 bright host galaxies potentially contaminating our!n survey. indicateOne whether fundamental the objects challenge are found when in the searching vicinity of for M 96,new in dwarf r galaxies is that survey fields are almost always contaminatedµsersic(r) =Toµ0 test+ 1 how.0857 these background, galaxies will pollute(1) our de- 1 last checked: 19 December 2017. × r0 by galaxy groups in the background. A prime example for such tections we surveyed for dwarf galaxies within 300 kpc of each A105, page 3 of 13 Article number, page 4 of 12 Oliver Müller et al.: TheA&A Leo-I 615, group: A105 (2018) new dwarf galaxy and UDG candidates

Fig. 2.Fig.continued. 3. Fig. 2 continued.

2 wheresuchµ0 is host the (approximately Sérsic central surface the virial brightness, radius) withr0 the the Sérsicsame meth-4.1. Membershiplow central surface estimation brightness (>25 B mag/arcsec ) galaxy, that scaleods length, as used and inn ourthe search Sérsic for curvature Leo-I dwarfs, index. but withoutThe total remov- comes in both early (i.e., dE) and late (i.e., Im V) types,” this extinctioning candidates corrected that absolute are near magnitude a backgroundM is galaxy. calculated Essentially, with weThe standardclass of galaxies approach is now for establishing called ultradi membershipffuse galaxies based (van Dokkum on a distancesearch modulus for the candidates of m M we= 30 rejected.06 mag, as background corresponding sources. to morphological In et al. 2015); properties these galaxies is to compare have been the found structural in many parame- different D = 10Table.4 Mpc, 3 we as compiled is used− the for coordinates Leo-I members for the with objects unknown that wouldters ofenvironments the candidates (van with der known Burg et dwarf al. 2016), galaxies for (e.g., example Jerjen in clus- distancebe considered estimates in as the dwarf LV candidates catalog (see based Fig. on3 theirfor all morphology. surface et In al. ters2000 (van; Chiboucas Dokkum et et al. 2015;2009; KodaMerritt et et al. al. 2015), 2014 and; Müller in groups et al. 2017a,b). If the objects fit into the ( µ – M), (r – M), brightnesstotal weprofiles found in 26 the additionalr band and dwarf the associatedcandidates, Sérsic of which fits). 20 are (Merritt et al. 2016). Different possibleh i formationeff scenarioseff have In Tableclustered A.2 we around provide NGC the 3607 derived at a distance photometry of for20 theMpc. new This in-(µ0 –beenM), andproposed (n – M (e.g.,) scaling Amorisco relations & Loeb defined 2016; by theDi Cintio known et al. ∼ candidates,dicates and that in (a) Tables it is not A.3 feasible and A.4 to include the previously every object known in the sur-dwarf2017) galaxies and in are the under local intense Universe, debate. it is reasonable van Dokkum to consider et al. (2015) them as dwarf galaxy candidates. The ( µ – M) and (µ – M) (dwarf)vey members footprint of as the Leo-I Leo-I dwarf, group. and (b) that there will probably be suggested classifying dwarf galaxiesh ie withff re f f > 1.05 kpc and a are especially crucial because the surface brightness is indepen- 2 Thesome magnitude confusionuncertainties between foreground are estimated and background, at around either by fainter central surface brightness than µg > 24.0 mag arcsec− as 0.3 magrejecting (Müller a foreground et al. 2017b dwarf). The or including main contributions a background to the dwarf.dentUDGs; of the assumed however, distance this boundary of the is object, rather arbitrary therefore and making should be error≈ budgetSome Leo-I are from dwarf the candidates uncertainties are related near both to foreground a background star hostit possibleconsidered to assess more the as membershipa guideline. at a certain distance (see removaland ( a0.2 Leo-I mag) host. and Insky this background case we addedestimation a note ( 0.2 to mag).Table 1. ToMüllerStudying et al. 2017a the,properties Fig. 11 for what of the happens Leo-I to members galaxies with we con- ≈ ≈ unreasonable distance estimates in those relations). To transform The uncertaintiesthe north to for theµ Leoeff are Triplet driven there by the are uncertainties four Leo-I in candidates the sider dw1055+11, dw1117+15, dw1051+11, KK 96, and h i 2 our gr photometry to the Johnson system we used the following measured(dw1116 total+14, apparent dw1116 magnitude+15a, dw1116 ( 0.3 mag+15b, arcsec and− dw1117). The +15) ACG 215415 as UDG candidates. With r = 1.3 kpc ≈ equations (Lupton 2005): e f f errorclustered for reff ( around1.3 arcsec) NGC is 3596 given (15 by Mpc).the determination The distribution of the of the dw1137+16 is still considerably large and could be a UDG type. growthbackground curve.≈ Numerical dwarf galaxies uncertainties can be for seen the Sérsic in Fig. parameters 8. Distance and Better photometry is needed to derive the structural parameters V = g 0.5784 (g r) 0.0038. (2) are providedvelocity in measurements the corresponding will be table. crucial to distinguish their mem- more− accurately.× − However,0 − we note that if these objects were berships. Until then, the faint-end of the LF will be affected by more in the foreground (e.g., in the Canes Venatici-I cloud), they these uncertain cases. 4. Discussion B = rwould+ 1.3130 be closer(g tor)0 our+ 0 point.2271 of. view and therefore would(3) have smaller intrinsic× − sizes, making them common-sized dwarf galax- In the following we discuss the membership of the candidates Theies. structural parameters of the newly found dwarf can- based4.3. on UDG their candidatesmorphological parameters, the contamination didates,The and UDG of candidatesthe previously are distributed discovered in Leo-I the outskirts members of and the ag- of the field by nearby background galaxies, and the potential the Localgregates Group and dwarfnot in the population, central parts are of plotted the group. in Fig. This4. The is similar Originally discovered by Sandage & Binggeli (1984) and de- discovery of ultradiffuse galaxies (UDG). structuralto what parameters is found in of galaxy the dwarf clusters: candidates in galaxy fall clusters into the the UDG scribed as “a new type of very large diameter (10,000 pc), A105, page 4 of 13 Article number, page 5 of 12 O. Müller et al.: The Leo-IA group:&A proofs: new dwarfmanuscript galaxy no. and aanda UDG candidates

23 24 25 24 dw1013+18 r 24 dw1037+09 r dw1040+06 r dw1044+11 r dw1045+13 r ) ) ) ) ) 2 24 2 2 25 2 2 25 26 25 25 26 26

26 26 27 (mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag / 27 27 SB SB SB SB SB 27 27 28 28 28 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 25 30 0 2 4 6 8 10 12 14 16 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

23 24 24 22 24 dw1045+14a r dw1045+14b r dw1045+16 r dw1047+16 r dw1048+13 r 23 ) 24 ) ) ) ) 2 2 25 2 2 2 25 25 24 25 26 25 26 26 26 27 26 (mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag / 27 27 SB SB SB 27 SB 27 SB 28 28 28 28 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

24 24 24 24 dw1049+12a r dw1049+12b r dw1049+15 r dw1051+11 r 24 dw1055+11 r ) ) ) ) ) 2 2 2 2 2 25 25 25 25 25 26 26 26 26

(mag / arcsec(mag / arcsec(mag / 27 arcsec(mag / 27 arcsec(mag / 27 arcsec(mag /

26 27 SB SB SB SB SB 28 28 28 28 27 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

24 24 25 23 dw1059+11 r dw1101+11 r dw1109+18 r 24 dw1110+18 r dw1116+14 r ) ) ) ) ) 2 25 2 2 2 2 25 24 26 25 26 25 26 27

(mag / arcsec(mag / arcsec(mag / arcsec(mag / 26 arcsec(mag / arcsec(mag /

26 27

SB SB 27 SB SB SB 27 28 27 28 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

24 24 dw1116+15a r dw1116+15b r dw1117+15 r dw1117+12 r dw1118+13a r 25 25 ) ) ) 25 ) ) 2 2 2 2 25 2 25

26 26 26 26 26 (mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag /

27 27 27

SB 27 SB SB SB SB

28 27 28 28 0 5 10 15 20 0 2 4 6 8 10 12 14 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

24 25 24 25 dw1118+13b r dw1123+13 r dw1127+13 r 23 dw1130+20 r dw1131+15 r ) ) ) ) )

2 2 25 2 2 2 25 26 24 26 26 26

27 25 27 27 27 (mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag / arcsec(mag /

26 SB SB SB 28 SB SB 28 28 28 27 0 5 10 15 20 25 30 0 2 4 6 8 10 12 14 16 0 5 10 15 20 0 5 10 15 20 25 0 2 4 6 8 10 12 14 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

24 24 24 23 dw1137+16 r 25 dw1140+17 r dw1145+14 r dw1148+12 r dw1148+16 r ) ) ) ) ) 2 25 2 2 2 25 2 25 24

26 25 26 26 26

(mag / arcsec(mag / arcsec(mag / arcsec(mag / 27 arcsec(mag / arcsec(mag /

27 27 27

SB SB SB SB SB 27 28 28 28 28 28 0 10 20 30 40 50 0 5 10 15 20 25 30 35 0 2 4 6 8 10 12 0 5 10 15 20 25 30 0 5 10 15 20 25 r (arcsec) r (arcsec) r (arcsec) r (arcsec) r (arcsec)

23 dw1151+16 r ) 2 24

26 (mag / arcsec(mag / 27 SB 28

0 5 10 15 r (arcsec)

Fig. 3. Fig.Surface 4. Surface brightness brightness profiles profiles of all new of all dwarf new galaxy dwarf galaxy candidates candidates in r and in ther and best-fitting the best-fitting Sérsic profiles Sérsic profiles with 1σ withconfidence 1σ confidence intervals. intervals.

density drops nearly to zero in the central regions because they dwarf galaxies in the nearby universe and their morphology we relations defined by the Local Group dwarfs, thus we can et al. 2017). Here we compare the (g r)0 colors of the Leo-I assumecannot that the survive candidates the tidal are forces indeed inflicted dwarf on members them (van of the der Burggroupconsider dwarfs with these other candidates well-studied to be members− systems inof the Leo-ILV where group, ly- Leo-Iet group. al. 2016). Additionally, We note we that show it is not the feasible 44 UDG to candidates assess the UDGgr photometrying in the is vicinity available, of namely the M 96 the subgroup, Centaurus in group the Leo (Müller Triplet, or in thedistribution Coma Cluster in Leo-I discovered with only by van 5 or Dokkum 6 candidates. et al.(2015), et al. 2015in the, 2017a nearby) andfield. the To M101 confirm group their complex membership, (Müller follow-ups et al. are who only gave g band photometry and so we assume a color 2017b).required The calculated to either meanmeasure(g theirr) radialcolor velocities,and standard their devia- distances, or both. Some of the candidates− 0 are exceptionally large with low index of (g r) = 0.6 mag to transform them into V-band tion for the three group populations are (g r)0,Leo I = 0.491 5. Conclusion− surface brightness, a characteristic of− ultradi− ffuse galaxies.± If magnitudes. UDGs typically have an effective radius larger 0.282 mag, (g r) , = 0.463 0.258 mag, and (g r) , = these UDGs− 0 Cen areA confirmed± as Leo-I members,− they0 M 101 would be than reWeff > have1.5 kpc surveyed and a 500central square surface degrees brightness of gr images fainter taken than from0.472 0.190 mag. In Fig.5 we show the color distribution 2 some± of the closest UDGs to Earth and valuable targets that µg > 24SDSS.0 mag within arcsec the− ( extendedvan Dokkum region et al.of the2015 Leo-I). group and foundas a function of total absolute V-magnitude for these different Dwarf36 new galaxies dwarf can galaxy also be candidates. characterized For every by their known color member using andgroups.could The be dwarfs used into theimprove different our understandinggalaxy groups offollow this galaxya sim- type. the color-magnitudenew candidate relationwe derived (e.g., surface Lisker brightness et al. 2008 photometry.; Venhola Basedilar distributionAcknowledgements. in theirOM colors. and BB We are note grateful that to the the Swiss extreme National blue Science on a comparison of their structural properties with other known Foundation for financial support. HJ acknowledges the support of the Australian

Article number, page 6 of 12 A105, page 5 of 13 OliverOliver Müller Müller et et al.: al.: The The Leo-I Leo-I group: group: new new dwarf dwarf galaxy galaxy and and UDG UDG candidates candidates Oliver Müller et al.: The Leo-I group: new dwarf galaxy and UDG candidates A&A 615, A105 (2018)

44 4 1616 16 18 3.5 18 3.5 18 3.5 ]

] 20 2 20 2 ] 20 2 33 22 3 22 [pc] 22 [pc] [pc] eff

eff 24

eff 24 24

2.5 [mag/arcsec log r

2.5 [mag/arcsec log r 26

0,V 26 0,V 26 0,V 2828 22 28 2 3030 30

1.51.5 3232 1.5-20-20 -15 -15 -10 -10 -5 -5 32-20-20 -15 -15 -10 -10 -5 -5 -20 -15 -10 -5 -20 -15 -10 -5 MM [mag][mag] MM [mag][mag] MVV [mag] MVV [mag] V V Fig. 5. Scaling relations (re f f – M) and (µ0 – M) for the newly discovered dwarf candidates (red squares), previously discovered dwarf members Fig. 5. Scaling relations (re f f – M) and (µ0 – M) for the newly discovered dwarf candidates (red squares), previously discovered dwarf members µ µ Fig.(grayFig.(gray 4. Scaling 5. squares), squares),Scaling relations relationsand and the the (re Local Localﬀ (r–e f fM– Group) GroupM and) and ( dwarf dwarf0 (– 0M– galaxy galaxy)M for) for the population population the newly newly discovered (gray (graydiscovered dots). dots). dwarf dwarf The The candidates estimated estimated candidates (red conservative conservative (red squares), squares), completenesspreviously completeness previously discovered discoveredlimit, limit, as as dwarf derived derived dwarf members in in members Müller Müller (gray(grayet squares),al. (2017b), squares), and is and the indicated Local the Local Group with Group the dwarf line. dwarf galaxy The galaxy UDG population candidates population (gray discovered (graydots). dots).The in estimated TheComa estimated (van conservative Dokkum conservative et completeness al. 2015) completeness are limit, overlaid as limit, derived as black as derived in dotsMüller in in the et Müller al. (re f f et al. (2017b), is indicated with the line. The UDG candidates discovered in Coma (van Dokkum et al. 2015) are overlaid as black dots in the (re f f (2017b–et– MM al.),)) diagram;(2017b), is diagram; indicated is also also indicated with overlaid overlaid the withline. is is the the theThe size size line. UDG cut cut The candidates(dashed (dashed UDG candidatesline) line) discovered of of 1.5 1.5 discovered kpc kpc in for for Coma UDGs. UDGs. in (van Coma Dokkum (van Dokkum et al. 2015 et) al. are 2015) overlaid are overlaid as black as dots black in the dots (r ineﬀ the– M (r)e f f diagram;– M) diagram; also overlaid also is overlaid the size is cut the (dashed size cut line) (dashed of 1.5 line) kpc of for 1.5 UDGs. kpc for UDGs.

22 2 100100 Leo-ILeo-I 1.51.5 100 Leo-I 1.5 CenCen AA 80 Cen A 1 gal 80 1 gal 80 1 gal LG 0.50.5 60 LG [mag] 60 LG [mag] 0.5 0 60 0 [mag]

0 00 0 40 NGC2784NGC2784 40 NGC2784 (g - r) 40 (g - r) -0.5-0.5 cumulative N (g - r) -0.5 cumulative N

cumulative N M101 2020 M101 -1-1 20 M101 -1 -1.5-1.5 00 -1.5-18-18 -16 -16 -14 -14 -12 -12 -10 -10 0-18-18 -16 -16 -14 -14 -12 -12 -10 -10 -8 -8 -18 -16 -14 -12 -10 -18 -16 -14 -12 -10 -8 MM [mag][mag] MM [mag][mag] MVV [mag] MVV [mag] V V ff Fig.Fig.Fig. 5. Color-magnitude 6. 6.Color-magnitudeColor-magnitude relation relation relation for for forthe the the previously previously previously known known known Leo-I Leo-I Leo-I dwarf dwarf dwarfFig.Fig.Fig. 6. 7. 7.CumulativeCumulativeCumulative galaxy galaxy galaxy luminosity luminosity luminosity functions functions functions for for for different di differenterent galaxy galaxy galaxy ff membersmembersFig.members 6. (grayColor-magnitude (gray (gray squares), squares), squares), the the relationthe new new new Leo-I Leo-Ifor the members members previously (red (red (red known squares), squares), squares), Leo-I the the the dwarf Cen- Cen-groupsgroupsFig.groups 7.in in inCumulative the the the Local Local Local Volume. Volume. Volume.galaxy luminosity Data Data taken taken taken functions from from from Leo-I Leo-I Leo-I for (this (this di (thiserent work), work), work), galaxy Cen- Cen- Centaurustaurusmemberstaurus group group group (gray members members members squares), (black (black (black the new dots, dots, dots, Leo-I Müller MüllerMüller members et et et al. al. al. (red2015,2015, 2015 squares),, 2017a), 2017a),2017a), the and and and Cen- the theCentaurustaurusgroupstaurus group group in group the (Müller (MüllerLocal (Müller Volume. et et al. al. 2015 2015, 2015, Data, 2017a taken2017a), 2017a),), from LG LG LG ( Leo-IMcConnachie (McConnachie (McConnachie (this work), 2012 2012), 2012), Cen-), theMtaurusM M 101 101 101 group group group members members members (black(blue (blue (blue crosses, crosses, dots, crosses, Müller Müller Müller Müller et etet al. al. etal. 2015, al.2017b). 2017b). 2017b 2017a), Both Both). Both and early- early- theNGCNGCtaurusNGC 2784 2784 2784 group group group group (Müller (Park (Park (Park et et al.et et al. al. al.2017 2015, 2017), 2017),), and 2017a), and and M 101M M101 LG101 group group(McConnachie group (Bremnes (Bremnes (Bremnes et 2012), al.et et al. al. early-andMand 101 and late-type late-type grouplate-type dwarf membersdwarf dwarf galaxies galaxies galaxies (blue were were crosses, were considered. considered. considered. Müller et al. 2017b). Both early-19991999;NGC1999;; Müller 2784 Müller Müller et group al. et et al.2017b al. (Park 2017b). 2017b).). et al. 2017), and M 101 group (Bremnes et al. and late-type dwarf galaxies were considered. 1999; Müller et al. 2017b).

Research Council through Discovery Project DP150100862. We thank the ref- Bullock, J. S. & Boylan-Kolchin, M. 2017, ARA&A, 55, 343 colorsResearch (g Councilr < 0) ofthrough some Discovery objects, Project which DP150100862. is uncommon We for thank dwarf the ref- Bullock,Under J. the S. & assumption Boylan-Kolchin, that M. 2017,all candidates ARA&A, 55, are 343 members of ereeResearcheree for for− the the Council helpful helpful through comments. comments. Discovery Project DP150100862. We thank the ref- Carlin,Bullock,Carlin, J. J. J.L., L., S. Sand, Sand, & Boylan-Kolchin, D. D. J., J., Price, Price, P., P., M. et et al. al.2017, 2016, 2016, ARA&A, ApJ, ApJ, 828, 828, 55, L5 L5 343 galaxies,eree for theand helpful the scatter comments. at the faint-end of the scale can arise theCarrillo,Carlin,Carrillo, Leo-I J. A.,A., group,L., Bell, Bell,Sand, E.E. we D. F., F., J., can Bailin, Bailin, Price, determine J., J.,P., et et et al. al. al. 2017, 2017, 2016, the MNRAS, MNRAS,ApJ, galaxy 828, 465,luminosity 465, L5 5026 5026 func- from the photometric uncertainty. tionChiboucas,Carrillo,Chiboucas, (see A.,Fig. K., K., Bell,6 Jacobs,) Jacobs, andE. F., B. B.compare Bailin, A., A., Tully, Tully, J., et it R. al.R. to B., B.,2017, other & & Karachentsev, Karachentsev,MNRAS, nearby 465, galaxy I. I. 5026 D. D. 2013, 2013, group AJ, AJ, 146, 146, In the following we discuss some individual candidates that environments,Chiboucas,126126 K., Jacobs, i.e., the B. A., Centaurus Tully, R. B., group & Karachentsev, (Müller I. et D. 2013,al. 2015 AJ, 146,, Chiboucas,Chiboucas,126 K., K., Karachentsev, Karachentsev, I. I. D., D., & & Tully, Tully, R. R. B. B. 2009, 2009, AJ, AJ, 137, 137, 3009 3009 haveReferences interesting features. 2017aChiboucas,Crnojevi), thec,´ LGD., K., Sand, Karachentsev, (McConnachie D. J., Caldwell, I. D., 2012 & N., Tully, et), al. the R. 2014, B. M101 2009, ApJ, group AJ, 795, 137, L35 (Bremnes 3009 Referencesdw1037+09. This candidate has several knots within and etCrnojevi al. 1999c,´ ; D.,Müller Sand, D. et J., al. Caldwell, 2017b), N., and et al. the 2014, NGC2784 ApJ, 795, group L35 (Park References CrnojeviCrnojevic,ć,´ D., D., Sand, Sand, D. D. J., J., Spekkens, Caldwell,Spekkens, N., K., K., et et et al. al. al. 2014, 2016, 2016, ApJ, ApJ, ApJ, 795, 823, 823, L35 19 19 Amorisco, N. C. & Loeb, A. 2016, MNRAS, 459, L51 aroundAmorisco, the N. galaxy, C. & Loeb, which A. 2016, could MNRAS, either 459, be L51 bright giant stars or etDanieli,CrnojeviDanieli, al. 2017 S.,c, S.,´ ). D., van van Among Sand, Dokkum, Dokkum, D. theseJ., P., P., Spekkens, Merritt, Merritt, fiveA., groups,A., K., et et al. al. 2017, 2017,2016, the ApJ, Leo-IApJ, 837, 837,823, group 136 13619 is the Amorisco,Belokurov, N. V., C. Irwin, & Loeb, M. J., A. Koposov, 2016, MNRAS, S. E., et 459, al. 2014, L51 MNRAS, 441, 2124 globularBelokurov, clusters V., Irwin, (GC). M. J., Koposov, S. E., et al. 2014, MNRAS, 441, 2124 richestDiDanieli,Di Cintio, Cintio, galaxy S., A., A., van Brook, Brook, Dokkum,aggregate C. C. B., B., P., Dutton, Dutton, Merritt, with A. A.approximately A., A., A., et et etal. al. al. 2017, 2017, 2017, ApJ, MNRAS, MNRAS, 100 837, galaxies 136 466, 466, L1 L1 up Bennet,Belokurov,Bennet, P., P., Sand, Sand,V., Irwin, D. D. J., J., M. Crnojevi Crnojevi J., Koposov,c,ć,´ D., D., et S.et al. al.E., 2017, 2017, et al. ApJ,2014, ApJ, 850, 850, MNRAS, 109 109 441, 2124 Ferguson,DiFerguson, Cintio, H. A.,H. C. C. Brook, & & Sandage, Sandage, C. B., Dutton,A. A. 1990, 1990, A. AJ, AJ, A.,= 100, 100, et al. 1 1 2017, MNRAS, 466, L1 Bennet,Boylan-Kolchin,dw1110+18 P., Sand,. M.,D. Here J., Bullock, Crnojevi too J. therec,´ S., D., & et Kaplinghat, are al. 2017, several ApJ, M. 2011, 850, knots 109 MNRAS, sprinkled 415, L40 toFerguson,Ferrarese, an absolute H.L., C. Ford, magnitude & Sandage, H. C., Huchra, A. of 1990,M J.,V AJ,et al. 100, 2000,10 1, ApJS, in other 128,431 words if all throughBoylan-Kolchin, the object, M., which Bullock, could J. S., & be Kaplinghat, bright giant M. 2011, stars MNRAS, or GCs. 415, L40 candidatesFerrarese, L., are Ford, confirmed H. C., Huchra, as J., members. et al. 2000,− The ApJS, Leo-I 128, 431 group has Bremnes,Boylan-Kolchin,Bremnes, T., T., Binggeli, Binggeli, M., Bullock, B., B., & & Prugniel, Prugniel, J. S., & Kaplinghat,P. P. 1999, 1999, A&AS, A&AS, M. 2011, 137, 137, 337MNRAS, 337 415, L40 Haynes,Ferrarese,Haynes, M. M. L., P., P., Ford, Giovanelli, Giovanelli, H. C., Huchra,R., R., Martin, Martin, J., etA. A. al. M., M., 2000, et et al. al. ApJS, 2011, 2011, 128, AJ, AJ, 142,431 142, 170 170 Bremnes,dw1130+20 T., Binggeli,. ThisB., galaxy & Prugniel, has some P. 1999, bright A&AS, knots, 137,337 which could approximatelyHaynes, M. P., Giovanelli, twice as R., many Martin, dwarfs A. M., as et al. the 2011, LG AJ, and 142, a 170 steeper correspond to HII regions. faint-end slope of the LF, comparableArticleArticle to that number, number, of Cen page page A. 7The 7 of of 12 12 Article number, page 7 of 12 A105, page 6 of 13 A&A proofs: manuscript no. aanda

O. Müller et al.: The Leo-I group: new dwarf galaxy and UDG candidates

20 CVn 18

[deg] Leo-Tr 12 M96 10

4 12:00:00 11:00:00 10:00:00 [hr:mm:ss]

Fig.Fig. 8. 7. Same as as Fig. Fig.1, 1, but but with with background background host host galaxies galaxies (black (black squares) squares) andand the background the background dwarf dwarf galaxies galaxies (blue(blue crosses) crosses) that are that clustered are clustered around aroundthese hosts. these The hosts. background The background dwarfs would dwarfs be would considered be considered Leo-I dwarfs Leo-I (thanks dwarfs to (thanks their morphology) to their morphology) if they were if they not so were close not to so the close background to the backgroundhosts. See Sect. hosts. 4.2 See for Section details. 4.2 for details.

Henkel,M 101 C., and Javanmardi, NGC 2784 B., Martínez-Delgado, groups have shallower D., Kroupa, faint-end P., & Teuwen, slopes. K. Nikiel-Wroczygalaxies withnski,´ absolute B., Soida, magnitudes M., Bomans, D.M J.,B &< Urbanik, –19 and M. with 2014, radial ApJ, 1 This2017, indicates A&A, 603, that A18 galaxy groups with massive hosts have steeper velocities786, 144 vrad < 2000 km s− within our survey footprint. Exclud- Huchtmeier,faint-ends W. of K., the Karachentsev, LF. While I. the D., & faint-end Karachentseva, slopes V. E.of 2003, Leo-I A&A, and Park,ing H. the S., Leo-IMoon, D.-S., galaxies Zaritsky, this D., search et al. 2017, resulted ApJ, 848, in 19 24 bright host Cen401, A 483 are comparable, the Leo-I group contains more brighter Pawlowski,galaxies M.potentially S. 2018, Modern contaminating Physics Letters our A, survey. 33, 1830004 Ibata, R. A., Lewis, G. F., Conn, A. R., et al. 2013, NAT, 493, 62 Pawlowski, M. S., Pflamm-Altenburg, J., & Kroupa, P. 2012, MNRAS, 423, 1109 Javanmardi,galaxies in B., the Martinez-Delgado, range from –16 D., toKroupa, –14 mag P., et al.in 2016,V-bands, A&A, making 588, A89 it Rekola,To R., test Jerjen, how H., & these Flynn, background C. 2005, A&A, galaxies437, 823 will pollute our Jennings,more rich Z. G., (up Romanowsky, to MV = A.10 J.,). Brodie, In this J. P., range et al. (–16 2015, toApJ, –14 812,V L10mag), Sandage,detections A. & we Binggeli, surveyed B. 1984, for AJ,dwarf 89, 919galaxies within 300 kpc of each Jerjen,the LF H., of Binggeli, Leo-IB., is comparable & Freeman,− K. to C. that 2000, of AJ, the 119, LG. 593 Schlafly,such host E. F. (approximately & Finkbeiner, D. P. the 2011, virial ApJ, radius) 737, 103 with the same meth- Karachentsev, I. D. & Karachentseva, V. E. 2004, Astronomy Reports, 48, 267 Schneider,ods as used S. 1985, in our ApJ, search 288, L33 for Leo-I dwarfs, but without removing Karachentsev, I. D., Karachentseva, V. E., & Huchtmeier, W. K. 2001, A&A, Schombert, J. M., Pildis, R. A., & Eder, J. A. 1997, ApJS, 111, 233 366, 428 Sersic,candidates J. L. 1968, that Atlas are de near galaxias a backgroundaustrales galaxy. Essentially, we Karachentsev,4.2. Background I. D., Karachentseva, contamination V. E., Huchtmeier, W. K., & Makarov, D. I. Speller,search R. for & Taylor, the candidates J. E. 2014, ApJ, we rejected 788, 188 as background sources. In 2004, AJ, 127, 2031 Staveley-Smith,Table A.3 we L., compiled Davies, R. the D.,& coordinates Kinman, T. D. for 1992, theMNRAS, objects that 258, would334 One fundamental challenge when searching for new dwarf Karachentsev, I. D., Makarov, D. I., & Kaisina, E. I. 2013, AJ, 145, 101 Stierwalt,be considered S., Haynes, as M.dwarf P., Giovanelli, candidates R., etbased al. 2009, on theirAJ, 138, morphology. 338 In Kim,galaxies D., Jerjen, is that H., Mackey, survey D., fields Da Costa, are almost G. S., & always Milone, A. contaminated P. 2015, ApJ, Trentham,total we N. found & Tully, 26 R. additional B. 2002, MNRAS, dwarf 335, candidates, 712 of which 20 are by804, galaxy L44 groups in the background. A prime example for such Tully, R. B., Courtois, H. M., Dolphin, A. E., et al. 2013, AJ, 146, 86 Koda, J., Yagi, M., Yamanoi, H., & Komiyama, Y. 2015, ApJ, 807, L2 Tully,clustered R. B. & around Fisher, J.NGC R. 1988, 3607 Catalog at a distance of Nearby ofGalaxies20 Mpc. This indi- Kraan-Korteweg,a confusion is R. the C. & massive Tammann, elliptical G. A. 1979, galaxy Astronomische NGC 5485 Nachrichten, with its ∼ many dwarf companions (Makarov & Karachentsev 2011) situ- Tully,cates R. that B., Libeskind, (a) it is not N. I., feasible Karachentsev, to include I. D., et every al. 2015, object ApJ, 802, in the L25 sur- 300, 181 vanvey der footprint Burg, R. F. as J., Leo-I Muzzin, dwarf, A., & Hoekstra, and (b) H.that 2016, there A&A, will 590, probably A20 be Kroupa,ated P.,20 Famaey, Mpc behind B., de Boer, the K. Local S., et Volumeal. 2010, A&A, galaxy 523, M A32 101 (7 Mpc, ≈ vansome Dokkum, confusion P. G., Abraham, between R., foreground Merritt, A., et and al. 2015, background, ApJ, 798, L45 either by Kroupa,Nataf 2015 P., Theis,). Figure C., & Boily, 8 in C.Merritt M. 2005, et A&A, al.(2016 431,) 517 shows M 101, the Venhola, A., Peletier, R., Laurikainen, E., et al. 2017, A&A, 608, A142 Lisker, T., Grebel, E. K., & Binggeli, B. 2008, AJ, 135, 380 Watkins,rejecting A. E., a foreground Mihos, J. C., Harding, dwarf or P., including & Feldmeier, a J.background J. 2014, ApJ, dwarf. 791, 38 Lupton,background R. 2005, elliptical Transformations NGC between5485, and SDSS former magnitudes M 101 and dwarf other systems candidates (Merritt et al. 2014) that actually belong to the background Wittmann,Some C., Leo-ILisker, T., dwarf Ambachew candidates Tilahun, areL., et near al. 2017, both MNRAS, a background 470, 1512 https://www.sdss3.org/dr10/algorithms/sdssUBVRITransform.php/ Wong,host andO. I., a Ryan-Weber, Leo-I host. E. In V., this Garcia-Appadoo, case we added D. A., a et note al. 2006, to Table MNRAS, A.1. Makarov,galaxy population.D. & Karachentsev, Out I. of 2011, the MNRAS, seven dwarf 412, 2498 candidates reported To371, the 1855 north to the Leo Triplet there are four Leo-I candidates Makarova,by Merritt L. N., etMakarov, al.(2014), D. only I., Antipova, three wereA. V., Karachentsev, confirmed to I. D., be & M Tully, 101 Zwicky, F. 1956, Ergebnisse der exakten Naturwissenschaften, 29, 344 membersR. B. 2018, with MNRAS, HST 474, follow-up 3221 observations (Danieli et al. 2017). (dw1116+14, dw1116+15a, dw1116+15b, and dw1117+15) McConnachie, A. W. 2012, AJ, 144, 4 Recently, more new dwarf candidates were reported around clustered around NGC 3596 (15 Mpc). The distribution of the Merritt, A., van Dokkum, P., & Abraham, R. 2014, ApJ, 787, L37 background dwarf galaxies can be seen in Fig.7. Distance Merritt,M 101 A., (Bennet van Dokkum, et al. P., Danieli,2017; Müller S., et al. 2016, et al. ApJ, 2017b 833, 168), now await- Michel-Dansac,ing confirmation L., Duc, as P.-A., members Bournaud, by F., means et al. 2010, of distance ApJ, 717, or L143 velocity and velocity measurements will be crucial to distinguish their Moore,measurements. B., Ghigna, S., Some Governato, will F., potentially et al. 1999, ApJ, be 524,associated L19 with the memberships. Until then, the faint-end of the LF will be affected Müller, O., Jerjen, H., & Binggeli, B. 2015, A&A, 583, A79 by these uncertain cases. Müller,background O., Jerjen, elliptical H., & Binggeli, NGC 5485.B. 2017a, A&A, 597, A7 Müller,The O., possibilityJerjen, H., Pawlowski, of contamination M. S., & Binggeli, prompted B. 2016, us A&A, to study 595, A119 the Müller, O., Pawlowski, M. S., Jerjen, H., & Lelli, F. 2018, Science, 359, 534 background of the Leo-I group in more detail. In Müller et al. 4.3. UDG candidates Müller,(2017a O.,) we Scalera, used R., the Binggeli, Cosmicflows-2 B., & Jerjen, H. catalog 2017b, A&A,(Tully 602, et A119al. 2013) Nataf, D. M. 2015, MNRAS, 449, 1171 to determine the background contamination of the Centaurus Originally discovered by Sandage & Binggeli(1984) and Articlegroup. number, Here we page query 8 of 12 the Cosmicflows-2 catalog for bright described as “a new type of very large diameter (10 000 pc), A105, page 7 of 13 A&A 615, A105 (2018) low central surface brightness (>25 B mag arcsec−2) galaxy, Chiboucas, K., Karachentsev, I. D., & Tully, R. B. 2009, AJ, 137, 3009 that comes in both early (i.e., dE) and late (i.e., Im V) Chiboucas, K., Jacobs, B. A., Tully, R. B., & Karachentsev, I. D. 2013, AJ, 146, 126 types,” this class of galaxies is now called ultradiffuse galax- Crnojevic,´ D., Sand, D. J., Caldwell, N., et al. 2014, ApJ, 795, L35 ies (van Dokkum et al. 2015); these galaxies have been found Crnojevic,´ D., Sand, D. J., Spekkens, K., et al. 2016, ApJ, 823, 19 in many different environments (van der Burg et al. 2016), for Danieli, S., van Dokkum, P., Merritt, A., et al. 2017, ApJ, 837, 136 example in clusters (van Dokkum et al. 2015; Koda et al. 2015), Di Cintio, A., Brook, C. B., Dutton, A. A., et al. 2017, MNRAS, 466, L1 and in groups (Merritt et al. 2016). Different possible forma- Ferguson, H. C., & Sandage, A. 1990, AJ, 100, 1 Ferrarese, L., Ford, H. C., Huchra, J., et al. 2000, ApJS, 128, 431 tion scenarios have been proposed (e.g., Amorisco & Loeb Haynes, M. P., Giovanelli, R., Martin, A. M., et al. 2011, AJ, 142, 170 2016; Di Cintio et al. 2017) and are under intense debate. Henkel, C., Javanmardi, B., Martínez-Delgado, D., Kroupa, P., & Teuwen, K. van Dokkum et al.(2015) suggested classifying dwarf galax- 2017, A&A, 603, A18 Huchtmeier, W. K., Karachentsev, I. D., & Karachentseva, V. E. 2003, A&A, ies with reff > 1.5 kpc and a fainter central surface brightness µ > . 2 401, 483 than g 24 0 mag arcsec− as UDGs; however, this boundary Ibata, R. A., Lewis, G. F., Conn, A. R., et al. 2013, Nature, 493, 62 is rather arbitrary and should be considered more as a guideline. Javanmardi, B., Martinez-Delgado, D., Kroupa, P., et al. 2016, A&A, 588, A89 Studying the properties of the Leo-I members we consider Jennings, Z. G., Romanowsky, A. J., Brodie, J. P., et al. 2015, ApJ, 812, L10 dw1055+11, dw1117+15, dw1051+11, KK 96, and ACG 215415 Jerjen, H., Binggeli, B., & Freeman, K. C. 2000, AJ, 119, 593 Karachentsev, I. D., & Karachentseva, V. E. 2004, Astron. Rep., 48, 267 as UDG candidates. With r ff = 1.3 kpc dw1137+16 is still con- e Karachentsev, I. D., Karachentseva, V. E., & Huchtmeier, W. K. 2001, A&A, siderably large and could be a UDG type. Better photometry is 366, 428 needed to derive the structural parameters more accurately. How- Karachentsev, I. D., Karachentseva, V. E., Huchtmeier, W. K., & Makarov, D. I. ever, we note that if these objects were more in the foreground 2004, AJ, 127, 2031 (e.g., in the Canes Venatici-I cloud), they would be closer to our Karachentsev, I. D., Makarov, D. I., & Kaisina, E. I. 2013, AJ, 145, 101 Kim, D., Jerjen, H., Mackey, D., Da Costa, G. S., & Milone, A. P. 2015, ApJ, point of view and therefore would have smaller intrinsic sizes, 804, L44 making them common-sized dwarf galaxies. Koda, J., Yagi, M., Yamanoi, H., & Komiyama, Y. 2015, ApJ, 807, L2 The UDG candidates are distributed in the outskirts of the Kraan-Korteweg, R. C., & Tammann, G. A. 1979, Astron. Nachr., 300, 181 aggregates and not in the central parts of the group. This is Kroupa, P., Theis, C., & Boily, C. M. 2005, A&A, 431, 517 similar to what is found in galaxy clusters: in galaxy clusters Kroupa, P., Famaey, B., de Boer, K. S., et al. 2010, A&A, 523, A32 Lisker, T., Grebel, E. K., & Binggeli, B. 2008, AJ, 135, 380 the UDG density drops nearly to zero in the central regions Lupton, R. 2005, Transformations between SDSS magnitudes and other systems because they cannot survive the tidal forces inflicted on them https://www.sdss3.org/dr10/algorithms/sdssUBVRITransform. (van der Burg et al. 2016). We note that it is not feasible to assess php/ the UDG distribution in Leo-I with only 5 or 6 candidates. Makarov, D., & Karachentsev, I. 2011, MNRAS, 412, 2498 Makarova, L. N., Makarov, D. I., Antipova, A. V., Karachentsev, I. D., & Tully, R. B. 2018, MNRAS, 474, 3221 McConnachie, A. W. 2012, AJ, 144, 4 5. Conclusion Merritt, A., van Dokkum, P., & Abraham, R. 2014, ApJ, 787, L37 Merritt, A., van Dokkum, P., Danieli, S., et al. 2016, ApJ, 833, 168 We have surveyed 500 square degrees of gr images taken from Michel-Dansac, L., Duc, P.-A., Bournaud, F., et al. 2010, ApJ, 717, L143 SDSS within the extended region of the Leo-I group and found Moore, B., Ghigna, S., Governato, F., et al. 1999, ApJ, 524, L19 36 new dwarf galaxy candidates. For every known member and Müller, O., Jerjen, H., & Binggeli, B. 2015, A&A, 583, A79 new candidate we derived surface brightness photometry. Based Müller, O., Jerjen, H., Pawlowski, M. S., & Binggeli, B. 2016, A&A, 595, A119 Müller, O., Jerjen, H., & Binggeli, B. 2017a, A&A, 597, A7 on a comparison of their structural properties with other known Müller, O., Scalera, R., Binggeli, B., & Jerjen, H. 2017b, A&A, 602, A119 dwarf galaxies in the nearby universe and their morphology we Müller, O., Pawlowski, M. S., Jerjen, H., & Lelli, F. 2018, Science, 359, 534 consider these candidates to be members of the Leo-I group, Nataf, D. M. 2015, MNRAS, 449, 1171 lying in the vicinity of the M 96 subgroup, in the Leo Triplet, or Nikiel-Wroczynski,´ B., Soida, M., Bomans, D. J., & Urbanik, M. 2014, ApJ, 786, 144 in the nearby field. To confirm their membership, follow-ups are Park, H. S., Moon, D.-S., Zaritsky, D., et al. 2017, ApJ, 848, 19 required to either measure their radial velocities, their distances, Pawlowski, M. S. 2018, Mod. Phys. Lett. A, 33, 1830004 or both. Some of the candidates are exceptionally large with Pawlowski, M. S., Pflamm-Altenburg, J., & Kroupa, P. 2012, MNRAS, 423, 1109 low surface brightness, a characteristic of ultradiffuse galaxies. Rekola, R., Jerjen, H., & Flynn, C. 2005, A&A, 437, 823 If these UDGs are confirmed as Leo-I members, they would Sandage, A., & Binggeli, B. 1984, AJ, 89, 919 Schlafly, E. F., & Finkbeiner, D. P. 2011, ApJ, 737, 103 be some of the closest UDGs to Earth and valuable targets that Schneider, S. 1985, ApJ, 288, L33 could be used to improve our understanding of this galaxy type. Schombert, J. M., Pildis, R. A., & Eder, J. A. 1997, ApJS, 111, 233 Sersic, J. L. 1968, Atlas de galaxias australes (Córdoba, Argentina: Observatorio Astronómico) Acknowledgements. OM and BB are grateful to the Swiss National Science Speller, R., & Taylor, J. E. 2014, ApJ, 788, 188 Foundation for financial support. HJ acknowledges the support of the Australian Staveley-Smith, L., Davies, R. D., & Kinman, T. D. 1992, MNRAS, 258, 334 Research Council through Discovery Project DP150100862. We thank the referee Stierwalt, S., Haynes, M. P., Giovanelli, R., et al. 2009, AJ, 138, 338 for the helpful comments. Trentham, N., & Tully, R. B. 2002, MNRAS, 335, 712 Tully, R. B., & Fisher, J. R. 1988, Catalog of Nearby Galaxies (Cambridge University Press) References Tully, R. B., Courtois, H. M., Dolphin, A. E., et al. 2013, AJ, 146, 86 Tully, R. B., Libeskind, N. I., Karachentsev, I. D., et al. 2015, ApJ, 802, L25 Amorisco, N. C., & Loeb, A. 2016, MNRAS, 459, L51 van der Burg, R. F. J., Muzzin, A., & Hoekstra, H. 2016, A&A, 590, A20 Belokurov, V., Irwin, M. J., Koposov, S. E., et al. 2014, MNRAS, 441, 2124 van Dokkum, P. G., Abraham, R., Merritt, A., et al. 2015, ApJ, 798, L45 Bennet, P., Sand, D. J., Crnojevic,´ D., et al. 2017, ApJ, 850, 109 Venhola, A., Peletier, R., Laurikainen, E., et al. 2017, A&A, 608, A142 Boylan-Kolchin, M., Bullock, J. S., & Kaplinghat, M. 2011, MNRAS, 415, L40 Watkins, A. E., Mihos, J. C., Harding, P., & Feldmeier, J. J. 2014, ApJ, 791, 38 Bremnes, T., Binggeli, B., & Prugniel, P. 1999, A&AS, 137, 337 Wittmann, C., Lisker, T., Ambachew Tilahun, L., et al. 2017, MNRAS, 470, 1512 Bullock, J. S., & Boylan-Kolchin, M. 2017, ARA&A, 55, 343 Wong, O. I., Ryan-Weber, E. V., Garcia-Appadoo, D. A., et al. 2006, MNRAS, Carlin, J. L., Sand, D. J., Price, P., et al. 2016, ApJ, 828, L5 371, 1855 Carrillo, A., Bell, E. F., Bailin, J., et al. 2017, MNRAS, 465, 5026 Zwicky, F. 1956, Ergebnisse der exakten Naturwissenschaften, 29, 344

A105, page 8 of 13 O. Müller et al.: The Leo-I group: new dwarf galaxy and UDG candidates

Appendix A: Tables Table A.1. Names, coordinates, and morphological types of the 36 new dwarf galaxy candidates of the Leo-I group.

α δ Name (J2000) (J2000) Type Notes

dw1013+18 10:13:29.0 +18:36:44 dIrr/dSph field dw1037+09 10:37:40.7 +09:06:20 dIrr M 96 dw1040+06 10:40:30.3 +06:56:28 dSph field dw1044+11 10:44:33.0 +11:16:10 dSph M 96 dw1045+14a 10:45:00.6 +14:06:20 dIrr/dSph M 96 dw1045+14b 10:45:56.3 +14:13:37 dSph M 96 dw1045+16 10:45:56.3 +16:55:00 dSph, bg? M 96 dw1045+13 10:45:58.1 +13:32:52 dSph M 96 dw1047+16 10:47:00.0 +16:08:50 dSph,N M 96 dw1048+13 10:48:35.7 +13:03:34 dSph M 96 dw1049+12a 10:49:11.4 +12:47:34 dSph M 96 dw1049+15 10:49:14.3 +15:58:20 dSph/dIrr M 96 dw1049+12b 10:49:25.8 +12:33:08 dSph/dIrr? M 96 dw1051+11 10:51:03.8 +11:01:13 dSph, UDG? M 96 dw1055+11 10:55:43.5 +11:58:05 dSph,N, UDG? M 96 dw1059+11 10:59:50.9 +11:25:38 dSph M 96 dw1101+11 11:01:22.5 +11:45:12 dSph M 96 dw1109+18 11:09:08.5 +18:54:22 dIrr/dSph field dw1110+18 11:10:54.9 +18:58:52 dSph field dw1116+14 11:16:14.4 +14:38:21 dSph, bg? Leo-Tr dw1116+15a 11:16:17.1 +15:04:02 dSph, bg? Leo-Tr dw1116+15b 11:16:46.4 +15:54:19 dIrr/dSph, bg? Leo-Tr dw1117+15 11:17:02.1 +15:10:17 dSph, UDG?, bg? Leo-Tr dw1117+12 11:17:44.2 +12:50:10 dSph Leo-Tr dw1118+13a 11:18:15.9 +13:30:53 dSph Leo-Tr dw1118+13b 11:18:53.3 +13:48:18 dSph Leo-Tr dw1123+13 11:23:56.4 +13:46:41 dSph Leo-Tr dw1127+13 11:27:13.0 +13:46:50 dSph Leo-Tr dw1130+20 11:30:32.0 +20:45:41 dIrr field dw1131+15 11:31:01.0 +15:54:52 dSph field dw1137+16 11:37:45.6 +16:31:09 dSph, UDG? field dw1140+17 11:40:43.0 +17:38:33 dSph field dw1145+14 11:45:32.1 +15:52:50 dSph field dw1148+12 11:48:09.1 +12:48:47 dSph field dw1148+16 11:48:45.0 +16:44:24 dIrr/dSph field dw1151+16 11:51:15.2 +16:00:20 dSph field

A105, page 9 of 13 A&A 615, A105 (2018)

Table A.2. Photometric and structural parameters of the new dwarf candidates in the surveyed region of the Leo-I group.

Name gtot rtot Ag Ar Mr (g r)0,tot µ0,r r0,r nr µ eff,r reff,r log reff,r − 2 h i 2 mag mag mag mag mag mag mag arcsec− arcsec mag arcsec− arcsec log pc (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

M 96 subgroup dw1037+09 17.61 17.09 0.080 0.056 –13.04 0.496 24.04 0.05 9.96 0.38 1.68 0.14 25.44 18.7 2.97 ± ± ± dw1044+11 19.39 19.17 0.088 0.061 –10.97 0.200 25.42 0.45 10.87 5.89 0.87 0.40 26.59 12.1 2.78 ± ± ± dw1045+14a 19.02 18.68 0.097 0.067 –11.46 0.313 22.79 0.63 1.25 1.14 0.56 0.16 24.87 6.92 2.54 ± ± ± dw1045+14b 19.79 19.29 0.094 0.065 –10.85 0.470 24.50 0.17 5.24 0.83 1.13 0.18 25.39 6.61 2.52 ± ± ± dw1045+16 18.50 17.62 0.085 0.059 –12.51 0.854 24.59 0.30 8.39 3.22 0.81 0.24 26.43 23.0 3.06 ± ± ± dw1045+13 18.81 18.08 0.110 0.076 –12.07 0.696 24.96 0.15 7.41 0.70 1.92 0.52 26.59 20.0 3.00 ± ± ± dw1047+16 18.07 17.91 0.091 0.063 –12.23 0.128 22.77 0.55 1.32 1.18 0.49 0.13 25.17 11.2 2.75 ± ± ± dw1048+13 19.83 18.67 0.111 0.077 –11.48 1.126 25.53 0.10 13.63 0.64 2.94 0.78 26.19 12.6 2.80 ± ± ± dw1049+12a 19.39 18.98 0.088 0.061 –11.16 0.386 23.78 0.49 2.92 1.91 0.67 0.19 25.54 8.18 2.61 ± ± ± dw1049+15 18.56 17.88 0.088 0.061 –12.26 0.655 24.30 0.12 9.38 0.90 1.42 0.23 25.08 10.9 2.74 ± ± ± dw1049+12b 19.10 18.05 0.085 0.059 –12.08 1.020 24.74 0.28 9.76 3.03 0.96 0.36 26.04 15.7 2.90 ± ± ± dw1051+11 17.85 16.95 0.092 0.063 –13.19 0.872 25.34 0.07 16.76 0.63 4.15 1.20 26.20 28.2 3.15 ± ± ± dw1055+11 17.59 16.40 0.066 0.046 –13.72 1.169 24.88 0.28 18.86 3.90 0.97 0.54 26.18 36.0 3.25 ± ± ± dw1059+11 18.98 18.60 0.060 0.041 –11.51 0.359 24.61 0.11 9.73 0.72 1.68 0.26 25.02 7.65 2.58 ± ± ± dw1101+11 19.47 19.45 0.058 0.040 –10.66 0.005 23.33 1.62 1.16 2.78 0.50 0.32 25.56 6.64 2.52 ± ± ±

Leo Triplet dw1116+14 20.33 19.57 0.071 0.049 –10.56 0.742 25.67 0.13 10.63 0.58 3.28 1.11 25.81 7.08 2.55 ± ± ± dw1116+15a 20.26 19.80 0.076 0.052 –10.33 0.437 25.11 0.32 6.79 2.43 0.95 0.28 25.98 6.88 2.54 ± ± ± dw1116+15b 20.42 19.31 0.068 0.047 –10.81 1.091 25.33 0.26 8.85 2.61 1.00 0.32 27.02 13.8 2.84 ± ± ± dw1117+15 17.56 17.25 0.082 0.057 –12.88 0.280 25.57 0.07 17.11 0.51 3.79 0.92 27.31 40.9 3.31 ± ± ± dw1117+12 21.22 19.87 0.073 0.050 –10.25 1.322 25.24 0.52 7.29 4.29 0.93 0.51 26.10 7.02 2.54 ± ± ± dw1118+13a 19.49 19.59 0.077 0.053 –10.54 –0.11 25.88 0.24 14.36 1.94 1.74 1.02 26.36 9.04 2.65 ± ± ± dw1118+13b 18.15 17.78 0.069 0.047 –12.34 0.341 25.33 0.13 15.09 1.66 1.35 0.24 26.45 21.5 3.03 ± ± ± dw1123+13 19.62 19.08 0.079 0.054 –11.05 0.513 24.95 0.16 8.74 1.05 1.55 0.31 25.38 7.26 2.56 ± ± ± dw1127+13 19.76 18.85 0.093 0.064 –11.28 0.872 25.51 0.13 12.85 0.95 1.72 0.52 26.10 11.2 2.75 ± ± ±

Field dw1013+18 18.02 17.65 0.106 0.073 –12.50 0.340 22.67 0.10 3.29 0.38 0.76 0.04 24.16 7.99 2.60 ± ± ± dw1040+06 17.96 18.22 0.120 0.083 –11.94 –0.29 24.36 0.12 8.18 0.88 1.20 0.17 25.37 10.7 2.73 ± ± ± dw1109+18 17.73 17.18 0.077 0.054 –12.95 0.523 23.25 0.06 7.35 0.41 1.07 0.06 24.17 9.94 2.70 ± ± ± dw1110+18 18.00 17.39 0.077 0.053 –12.74 0.587 24.30 0.11 12.15 1.16 1.20 0.20 25.15 14.2 2.85 ± ± ± dw1130+20 17.53 17.28 0.068 0.047 –12.84 0.220 22.63 0.14 2.75 0.58 0.61 0.05 24.49 10.9 2.74 ± ± ± dw1131+15 19.51 18.87 0.171 0.118 –11.32 0.581 24.59 0.09 7.39 0.42 1.97 0.24 25.22 7.43 2.57 ± ± ± dw1137+16 17.32 16.77 0.097 0.067 –13.37 0.523 24.49 0.12 14.19 1.99 0.89 0.10 25.89 26.6 3.12 ± ± ± dw1140+17 18.54 17.89 0.098 0.068 –12.25 0.623 24.85 0.20 13.96 3.30 0.87 0.23 25.67 14.3 2.85 ± ± ± dw1145+14 19.86 19.20 0.147 0.101 –10.97 0.613 24.02 0.12 4.94 0.49 1.39 0.17 24.65 4.89 2.39 ± ± ± dw1148+12 17.95 17.91 0.119 0.082 –12.25 0.002 24.58 0.20 9.02 1.75 1.02 0.29 25.78 14.9 2.87 ± ± ± dw1148+16 17.49 17.34 0.150 0.104 –12.84 0.109 22.85 0.06 3.77 0.32 0.78 0.04 24.61 11.3 2.75 ± ± ± dw1151+16 18.04 18.27 0.109 0.075 –11.88 –0.25 22.92 0.07 3.92 0.25 1.09 0.05 23.86 5.24 2.42 ± ± ± Notes. The quantities listed are as follows: (1) name of candidate; (2–3) total apparent magnitude in the g and r bands; (4–5) galactic extinction in the g and r bands (Schlaﬂy & Finkbeiner 2011); (6) extinction corrected absolute r band magnitude, using a distance modulus of M m = 30.06 mag; (7) integrated and extinction corrected g r color; (8) Sérsic central surface brightness in the r band; (9) Sérsic scale length in− the r band; (10) Sérsic curvature index in the r band; (11)− mean effective surface brightness in the r band; (12) effective radius in the r band; (13) the logarithm of the effective radius in the r band, converted to pc with a distance modulus of M m = 30.06 mag. We note that surface brightness values presented are not extinction corrected. −

A105, page 10 of 13 O. Müller et al.: The Leo-I group: new dwarf galaxy and UDG candidates

Table A.3. Coordinates of the possible background dwarf galaxy in our survey footprint around bright host galaxies with v < 2000 km s2.

α δ Name (J2000) (J2000)

NGC 3227_1 10:22:53 +19:34:36 NGC 3227_2 10:24:43 +19:57:16 NGC 3227_3 10:25:50 +19:43:22 NGC 3666_1 11:24:45 +11:20:04 NGC 3666_2 11:24:10 +11:25:12 NGC 3370_1 10:46:47 +17:16:18 NGC 3607_1 11:14:22 +18:02:38 NGC 3607_2 11:14:26 +18:22:30 NGC 3607_3 11:15:35 +18:25:21 NGC 3607_4 11:15:36 +18:01:04 NGC 3607_5 11:15:48 +18:04:40 NGC 3607_6 11:15:52 +17:54:04 NGC 3607_7 11:15:57 +17:56:25 NGC 3607_8 11:16:11 +17:57:04 NGC 3607_9 11:16:18 +18:35:39 NGC 3607_10 11:16:28 +18:11:35 NGC 3607_11 11:16:30 +18:19:27 NGC 3607_12 11:17:01 +18:18:07 NGC 3607_13 11:17:07 +17:19:09 NGC 3607_14 11:17:16 +18:46:27 NGC 3607_15 11:17:22 +17:59:50 NGC 3607_16 11:18:21 +17:41:50 NGC 3607_17 11:19:13 +18:05:47 NGC 3607_18 11:19:21 +17:32:09 NGC 3607_19 11:24:08 +18:13:16 NGC 3607_20 11:31:01 +15:54:48

A105, page 11 of 13 A&A 615, A105 (2018) 1 − v band; (13) logarithm r D Ref r , bands ( Schlaﬂy & Finkbeiner ); 2011 pc Mpc km s r e f f r log log and g color; (8) Sérsic central surface brightness in r , r e f f r − arcsec g 2 − band; (12) effective radius in the r , r e f f i 23.17 9.35 2.72 (AA) 686 (AA) 25.14 17.9 2.95 (FS) 832 (H+) 25.10 7.30 2.56 (LV) 22.13 2.41 2.08 (AA) 10.43 (LV) 915 (AA) 22.15 12.6 2.80 541 (LV) 20.15 7.10 2.55 (AA) 1175 (AA) 26.31 20.8 3.02 (TT) 636 (AA) µ 22.91 8.48 2.63 (AA) 828 (LV) 22.91 8.99 2.65 (FS) 780 (AA) 24.71 17.5 2.94 (FS) 22.57 12.2 2.79 (FS) 772 (AA) 24.37 13.7 2.84 (S+) 847 (AA) 25.37 28.8 3.16 (LV) 22.87 6.17 2.49 (AA) 1177 (AA) 22.97 19.1 2.98 1008 (AA) 22.97 13.0 2.81 (AA) 724 (AA) 25.07 7.33 2.56 (LV) 23.00 13.7 2.83 777 (AA) 23.70 16.2 2.91 (S+) 24.70 7.64 2.58 (LV) 24.95 14.3 2.86 (S+) 23.69 14.7 2.87 (S+) 989 (S+) 23.83 12.0 2.78 (LV) 24.52 11.2 2.75 (LV) 22.24 9.44 2.67 (AA) 824 (LV) 22.99 5.77 2.46 (AA) 832 (LV) 23.52 14.3 2.85 (LV) 630 (LV) 23.06 22.0 3.07 11.07 (R+) 1073 (LV) 25.09 5.85 2.47 (LV) 25.20 16.2 2.91 (FS) 22.95 33.1 3.09 7.73 (LV) 573 (H+) 24.90 8.81 2.64 (TT) 843 (AA) 25.43 18.3 2.96 (FS) 23.86 16.0 2.90 (FS) 1030 (S+) 24.59 8.16 2.61 (FS) 24.92 10.4 2.72 (FS) 23.79 8.70 2.64 (FS) 871 (AA) 22.93 11.7 2.77 (AA) 633 (LV) 24.53 8.92 2.65 (LV) 25.29 23.8 3.07 (LV) 24.59 15.7 2.90 (LV) 1007 (AA) 24.43 9.58 2.68 (LV) 22.09 33.3 3.22 604 (AA) h 04 02 16 02 17 06 09 04 08 01 01 04 02 09 02 31 14 01 02 23 09 11 16 03 49 04 13 15 02 25 18 22 09 03 03 06 02 07 02 01 02 07 08 ...... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± n 26 87 19 87 68 59 15 17 38 90 85 24 05 05 79 44 27 73 14 86 37 11 47 02 00 00 70 39 92 57 63 71 05 01 17 50 82 90 98 97 77 28 12 ...... r , 0 43 1 31 0 65 1 14 0 48 1 26 1 81 1 34 1 33 1 09 0 11 0 15 1 25 1 24 1 11 0 76 1 03 1 09 0 36 1 46 1 70 1 73 1 62 0 30 1 75 2 55 1 34 1 67 1 20 0 36 0 57 1 31 0 46 1 42 1 22 1 36 1 15 0 59 0 19 0 16 0 55 0 36 1 17 1 ...... r 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 4 0 0 0 0 0 0 2 0 2 1 0 0 0 0 0 0 0 0 0 0 bands; (4–5) galactic extinction in the arcsec mag arcsec ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r 88 25 69 62 72 42 14 15 29 88 94 27 52 46 49 35 55 76 52 03 14 00 65 74 64 06 57 16 48 07 22 86 37 96 08 32 04 97 35 83 48 15 80 ...... and g 2 − 05 11 04 7 13 5 03 4 06 11 03 11 08 11 04 10 05 7 02 4 02 3 04 4 03 9 06 19 01 8 19 5 09 13 02 3 02 25 07 10 05 17 11 7 52 4 03 8 14 10 05 11 05 9 11 8 03 6 75 2 08 10 45 3 08 18 06 7 02 13 03 14 03 4 11 4 05 5 02 7 02 22 09 5 12 1 ...... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 mag; (7) integrated and extinction corrected r , mag; (14–16) reference for original discovery, distance measurement, and velocity measurement: ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0 µ 06 26 25 78 87 13 79 51 03 40 95 53 06 48 32 50 37 40 35 07 46 47 67 44 62 35 59 25 13 71 60 13 85 38 55 97 90 50 10 25 85 06 10 22 . 06 ...... 22 22 23 21 24 22 23 23 23 20 21 22 22 24 21 24 24 20 22 24 24 23 24 22 24 23 24 23 21 23 24 23 24 21 21 23 21 23 20 21 21 22 21 30 30 = = tot m , m 0 ) band; (11) mean effective surface brightness in the − r − r − M g M ( r M r A g A tot r tot band; (10) Sérsic curvature index in the g mag mag mag mag mag mag mag arcsec r band magnitude, using a distance modulus of r 12:47:19 18.37 17.12 0.074 0.052 –13.01 1.228 14:07:47 16.66 16.32 0.060 0.042 –14.07 0.317 14:10:21 18.98 18.29 0.061 0.042 –11.83 0.667 13:16:18 14.94 14.35 0.099 0.068 –15.93 0.565 11:29:31 17.17 16.92 0.103 0.071 –13.23 0.220 14:07:28 15.27 14.64 0.132 0.092 –15.52 0.580 11:21:06 17.79 17.16 0.102 0.071 –12.99 0.599 12:57:39 18.60 18.18 0.096 0.066 –11.96 0.391 11:45:21 18.63 18.03 0.085 0.058 –12.10 0.569 12:57:38 18.49 17.83 0.081 0.056 –12.31 0.638 14:01:25 16.99 16.48 0.098 0.068 –13.66 0.471 12:19:37 16.44 15.84 0.080 0.055 –14.30 0.578 12:21:34 16.65 16.07 0.084 0.058 –14.06 0.547 14:04:15 13.85 13.35 0.114 0.079 –16.16 0.465 15:35:21 18.18 17.78 0.104 0.072 –12.37 0.366 12:28:21 15.07 14.56 0.080 0.056 –15.58 0.486 15:01:50 16.86 16.27 0.072 0.050 –13.85 0.561 11:45:20 15.69 15.31 0.050 0.034 –14.77 0.356 11:59:53 17.79 17.16 0.055 0.038 –12.95 0.611 11:02:35 15.94 15.37 0.078 0.054 –14.76 0.547 11:55:00 17.59 17.10 0.073 0.050 –13.03 0.466 11:32:03 19.20 18.75 0.098 0.068 –11.40 0.421 15:20:13 15.92 15.39 0.123 0.085 –14.77 0.490 14:42:26 18.15 17.27 0.073 0.050 –12.86 0.856 14:06:53 17.75 17.18 0.107 0.074 –12.97 0.540 10:22:43 17.11 16.43 0.083 0.057 –13.70 0.646 10:22:52 14.32 13.90 0.094 0.065 –16.24 0.390 13:54:33 17.12 16.60 0.117 0.081 –13.56 0.481 12:59:54 17.72 16.88 0.098 0.068 –13.26 0.809 13:52:53 16.19 15.64 0.053 0.037 –14.47 0.530 13:29:02 19.66 19.25 0.104 0.072 –10.89 0.379 13:56:22 16.11 15.59 0.103 0.072 –14.56 0.487 12:00:35 16.20 15.85 0.065 0.045 –14.27 0.332 12:20:22 17.21 16.68 0.060 0.042 –13.44 0.512 12:50:56 16.30 15.75 0.079 0.054 –14.38 0.534 12:08:00 19.16 18.78 0.089 0.061 –11.35 0.352 12:09:02 17.03 16.41 0.082 0.057 –13.72 0.587 12:20:05 15.53 15.13 0.084 0.058 –15.00 0.373 12:42:25 13.08 12.48 0.082 0.057 –17.66 0.575 12:26:48 18.65 18.22 0.102 0.071 –11.94 0.398 12:44:07 18.10 17.53 0.090 0.062 –12.61 0.551 12:38:04 16.74 16.14 0.084 0.058 –13.99 0.573 12:44:26 18.05 17.72 0.073 0.051 –12.40 0.304 band, converted to pc with a distance modulus of + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + r Photometric and structural parameters of the previously known Leo-I members. The quantities listed are as follows: (1) name of candidate; (2–3) total apparent magnitude in the band; (9) Sérsic scale length in the CGCG 066–109 11:04:26 LSBCD 640–08 11:00:52 LeG 33 11:00:45 AGC 205278 10:58:52 LSBCD 640–14 10:58:10 LSBCD 640–13 10:56:14 LSBCD 640–12 10:55:56 LeG 28 10:53:01 LeG 27 10:52:20 AGC 202456 10:52:19 AGC 205544 10:52:05 AGC 205540 10:51:31 LeG 26 10:51:21 KK 96 10:50:27 UGC 05944 10:50:19 LeG 23 10:50:09 FS 40 (LeG 22) 10:49:37 CGCG 066–026 10:48:54 DDO 088 10:47:22 Le G21 10:47:01 FS 21 (KK94) 10:46:57 FS 20 (LeG 19) 10:46:55 LeG 18 10:46:53 FS 17 (LeG 17) 10:46:41 FS 15 (LeG 16) 10:46:30 FS 14 (KK 93) 10:46:25 FS 13 (LeG 14) 10:46:14 FS 09 (LeG 13) 10:44:57 AGC 205445 10:44:35 LeG 12 10:44:07 LeG 11 10:44:02 LeG 10 10:43:55 LeG 09 10:42:34 FS 04 10:42:00 UGC 05812 10:40:56 LeG 06 10:39:56 FS 01 (LeG 05) 10:39:43 LeG 04 10:39:40 AGC 200499 10:38:08 AGC 205165 10:37:05 NGC 3299 10:36:24 AGC 202248 10:34:56 Name M 96 subgroup AGC 205156 10:30:53 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) r Table A.4. Notes. (AA) ( Haynes et al. ),2011 (S+) (LV) ( Karachentsev ( Staveley-Smith & et al. Karachentseva ),2004 ; 1992 (TT)Karachentsev et ( Trentham & al. Tully 2004, 2002 ),),2013 and (FS) (H+) ( Ferguson ( Huchtmeier & et Sandage al. ),1990 2003 ). (S+) We ( Schombert note et that al. the),1997 surface (R+) brightness ( Rekola values et presented al. are), 2005 not extinction corrected. (6) extinction corrected absolute the of the effective radius in the

A105, page 12 of 13 O. Müller et al.: The Leo-I group: new dwarf galaxy and UDG candidates r g − g 1 − band; (12) v r D Ref r , pc Mpc km s ff e r log bands; (4–5) galactic extinction in the log r r , mag; (14–16) reference for original discovery, ff and e r 06 g . arcsec mag; (7) integrated and extinction corrected 30 06 2 . = − r 30 , m ff e i = − µ 21.31 17.2 2.94 10.52 (LV) 536 (AA) 21.95 9.80 2.74 11.70 (LV) 652 (LV) 23.12 18.5 2.97 588 (AA) 23.75 8.15 2.51 (AA) 8.22 (LV) 743 (LV) 24.71 9.51 2.57 (HI) 8.20 (LV) 1004 (AA) 22.71 5.86 2.49 (AA) 11.0 (LV) 630 (AA) 22.76 6.54 2.51 (AA) 790 (LV) 22.73 18.0 2.95 708 (LV) 25.27 7.43 2.57 (J+) 22.97 8.40 2.62 666 (AA) 24.38 9.82 2.52 (LV) 7.11 (LV) 623 (LV) 24.02 14.8 2.72 (KKH) 7.4 (LV) 881 (LV) 25.08 14.1 2.83 (KKH) 23.89 16.3 2.82 (KKH) 8.50 (LV) 880 (AA) 26.49 28.0 3.15 (AA) 1002 (AA) 22.85 9.98 2.70 (AA) 626 (LV) h m M band; (11) mean effective surface brightness in the − r M 20 10 05 04 13 01 04 05 06 03 01 01 38 02 01 06 ...... 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± n 42 13 77 49 97 12 88 07 59 87 60 63 36 85 65 08 ...... r , 0 30 2 65 1 27 1 18 1 48 1 12 1 51 0 64 1 88 3 23 0 09 0 08 0 23 1 13 0 18 0 38 1 ...... r 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 arcsec mag arcsec ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 36 03 55 71 15 87 54 03 10 73 11 05 52 92 75 07 ...... 2 − 05 11 10 7 02 16 03 7 04 18 02 6 04 10 07 11 08 21 06 3 02 3 03 2 18 8 04 2 04 3 12 4 ...... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r , ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0 µ 39 37 54 10 75 03 31 84 63 51 49 78 81 33 91 73 ...... 24 23 23 23 24 21 20 22 25 21 20 20 24 21 20 21 band; (10) Sérsic curvature index in the r tot , 0 ) r − band, converted to pc with a distance modulus of g ( band magnitude, using a distance modulus of r r r M r A g A band; (9) Sérsic scale length in the tot r r tot g mag mag mag mag mag mag mag arcsec 14:17:24 17.23 16.69 0.073 0.051 –13.44 0.522 21:19:18 17.49 17.34 0.077 0.053 –12.70 0.130 17:15:20 17.44 17.43 0.127 0.088 –11.91 –0.02 13:37:47 15.02 14.45 0.085 0.058 –15.68 0.538 11:01:07 16.51 16.17 0.082 0.057 –13.22 0.313 19:30:19 15.34 14.99 0.084 0.058 –15.40 0.322 10:21:48 13.41 13.13 0.133 0.092 –17.06 0.241 13:05:57 15.38 14.79 0.091 0.063 –15.35 0.566 14:08:46 16.22 15.83 0.126 0.087 –13.89 0.351 10:48:34 17.68 17.19 0.119 0.083 –12.46 0.447 13:26:50 19.63 18.92 0.085 0.059 –11.21 0.683 12:40:30 18.18 17.26 0.125 0.087 –12.91 0.881 12:53:46 16.74 16.35 0.088 0.061 –13.79 0.363 12:58:46 16.40 15.85 0.082 0.057 –14.28 0.522 12:38:52 17.26 16.87 0.063 0.044 –13.37 0.368 12:26:04 17.95 17.83 0.101 0.070 –11.80 0.096 + + + + + + + + + + + + + + + + band; (13) the logarithm of the effective radius in the r 11:21:37 ∗ continued. *: full name: NGC3628-DGSAT-1. The quantities listed are as follows: (1) name of candidate; (2–3) total apparent magnitude in the bands ( Schlafly & Finkbeiner );2011 (6) extinction corrected absolute r AGC 215145 11:54:12 LVJ1149+1715 11:49:06 KKH 69 11:34:53 AGC 213091 11:29:35 KKH 67 11:23:03 CGCG 095–078 10:58:02 Field UGC 05456 10:07:19 KKH 68 11:30:53 AGC 215415 11:24:34 IC 2791 11:23:38 IC 2787 11:23:19 AGC 213436 11:22:24 DGSAT–1 AGC 215354 11:19:16 IC 2684 11:17:01 Name Leo Triplet AGC 202256 11:14:45 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) Table A.4. Notes. and color; (8) Sérsic central surfaceeffective radius brightness in in the the distance measurement, and velocity( Karachentsev measurement: et (J+) al. ( Javanmardi),2001 et and al. (HI)), ( Wong2016 et (AA) al. ( Haynes2006 ). et We al. note),2011 that (LV) the ( Karachentsev surface & brightness Karachentseva values2004; presentedKarachentsev are et not al. extinction corrected.2004 , ),2013 (KKH)

A105, page 13 of 13